Tag Archives: Clean Rooms

Various types of clean benches are available that can serve as a more economical means to achieving specific cleanroom class areas within a critical environment

By Kevin Weist, Clean Air Products

Clean benches are one type of mini clean environment and offer a convenient method of controlling particulate contamination within a controlled work area. They do not require a user to be gowned, but individuals will often wear gloves and arm covering when using the bench as an extra measure of protection against particulate contamination.

Clean benches are used in a variety of industries, including semiconductor, pharmaceutical, medical device, health care, food, aerospace, nanotechnology, disk drive, injection molding, and automotive, among others. They can be used as a stand-alone solution, or inside a cleanroom-it is often more economical to supplement a cleanroom with clean benches for a localized Class 100/Class 10 area, rather than making the entire cleanroom Class 100 or Class 10 (ISO 5 or 4).


Figure 1. A clean bench can be used in conjunction with cleanrooms to create clean zones. It can also be used in lieu of a cleanroom. The Series 412 vertical laminar flow clean bench is an example of a freestanding, ultra-clean minienvironment. It is available in various styles from vertical flow benches with open interiors, to exhausting clean benches with wet process, to recirculating temperature-control Class 1 systems. Photo courtesy of Clean Air Products.
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Benches are available in a variety of configurations and modes of operation, with additional environmental controls available as necessary depending on their type and configuration. They range in size from compact tabletop versions to larger cabinets. Sizes are available from 2 to 10 ft in width, work area heights from 22 to 46 inches, and table depths up to 48 inches. Clean benches can have a vertical or horizontal airflow, and with smaller micro systems the air is often purged with a hose and removed through a HEPA filter system.


Figure 2. The Series 301 laminar flow workstation is a freestanding unit with a built-in table. This type of general purpose, horizontal flow clean bench is suited to various mechanical or processing tasks and is designed to provide Class 10 or Class 100 (ISO 4 or 5) clean air environments. Photo courtesy of Clean Air Products.
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Clean benches with either vertical or horizontal laminar airflow will provide the cleanest working environments, because the HEPA filtered air within these benches is unidirectional and turbulence free. Unidirectional is defined by the Federal Standard 209E as airflow having generally parallel streamlines, operating in a single direction, and with uniform velocity over its cross-section-also referred to as laminar.

Laminar airflow is the most efficient option for removing particulate contamination from the controlled area because the airflow uniformity and lack of turbulence keeps “clean air streams” from mixing and being contaminated by a contaminated air stream. An object being bathed with clean, turbulence-free, laminar airflow will remain clean and protected from nearby contamination as long as the two air streams remain unidirectional and devoid of turbulence.

Vertical and horizontal airflow each have strengths and weaknesses when it comes to keeping objects free from contamination. The challenge is that anytime an object is placed into an air stream it is not perfectly aerodynamic and will block some of the airflow, creating turbulence around the object. Where there is turbulence there is a reduced air exchange rate and a mixing with adjacent air streams. That turbulence can extend down the air stream from the object, and the energy from the turbulent area can draw air back upstream. If the turbulence is caused by an object in the air stream, the contamination can be drawn upstream back toward the object. When using a clean bench where the distance between the object within the clean environment and dirty ambient air is relatively short-typically less than 12 inches-one must be careful to locate these objects within the air stream to minimize the turbulence.


Figure 3. The rugged Series 201 is a horizontal flow unit with a table-mount configuration. Vinclad steel or painted structural materials deliver high resistance to abrasion, corrosion, stains, chemicals, scratches, and scuffs, and provide a visually attractive clean bench. Photo courtesy of Clean Air Products.
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To minimize turbulence within the clean bench, objects should be placed within the airflow such that the smallest cross-section is perpendicular to the airflow, with the air able to flow around as much of the object as possible. If the air path is long enough, the clean air will regain its uniform airflow subject to the size of the object. As a general rule, when clean air is traveling on two sides of an object the air will regain unidirectional flow at approximately three times the distance of the object’s width. If clean air can only get at one side of the object, this distance increases to approximately six times the object’s thickness. Careful positioning of items on the work surface can prevent turbulence and inflow contamination. When possible, setting objects on a raised platform will allow air to flow under the object and reduce downstream turbulence.

Horizontal airflow is generally best when the object has a large horizontal surface and/or a narrow cross-section perpendicular to the airflow. Horizontal airflow is also well suited when working directly over the object such that there is constant clean airflow flowing between the work object and the operator’s hands or work instruments. When using a clean bench with a standard 90 LFPM airflow velocity and a 30-inch work area, it takes less than two seconds for a complete air exchange to occur.

A typical horizontal flow clean bench has a table top and a three-sided hood; the air flows out the end of the hood like a “wall of air.” The wall of air extends beyond the end of table top, creating a semi-clean zone directly in front of the clean bench. In the event that contamination is created, if laminar airflow can be maintained everything upstream of the contamination will remain clean; the only area affected by the contamination would be that directly downstream of the contamination.

Vertical flow is used for any number of reasons, with the size and type of object being the primary considerations. Large objects can block the airflow from a horizontal flow bench, creating large turbulent areas on the downstream side of the object. These large turbulent areas often become contaminated as ambient contamination is drawn toward them. With vertical flow, air enters the work zone from the top and flows downward, surrounding the object within the work area. Air flows on the front, sides, and rear, bathing the object on all sides with clean HEPA filtered air. Vertical flow air then continues down through a perforated or rod-type table top, or turns and flows out the front of the bench if it’s a solid-top table.

The front of a vertical flow clean bench is open and relies on the outflow of air to maintain the clean environment. Adding a rigid or flexible front face shield or front sliding window will contain the work area and help direct the HEPA filtered air toward the critical work area. The shield will reduce the open frontal area to increase the exit air velocity and help prevent infiltration of contaminated air into the clean space.

The front shield also protects the vertical airflow air from the contaminated stationary air just in front of the bench. If these two air masses come in contact-one moving and one stationary-a turbulent boundary will develop that will result in the two air masses mixing and will deteriorate the laminar flow.

When using solid table tops or minimum perforated tops, most air flows out the front of the bench. There will be some airflow compromise in that it is not completely unidirectional, as the air turns toward the front and there will be an area of turbulence in the rear of the bench between the table top and back panel. Although this is not ideal, it is typically not problematic in most applications. Care should be taken to avoid placing critical objects within this turbulent area and doing work in this area that would generate contamination. This air will eventually clean itself, but does not do so as efficiently as in the laminar areas.

Adding some perforation to the table top or the rear of the back panel, or a small space between the back panel and table top, can minimize the turbulent area. Note that if holes are added to the rear of the hood, one must ensure that drafts from other air currents do not cross-flow through the bench. Adding a perforated or rod top allows the air to flow down through the table top in a more laminar manner. However, this does reduce the outflow of air from the front of the hood, making a front face shield or window even more important.

Not all clean benches are designed for a Class 100 (ISO 5) interior space. Even with HEPA filtered air feeding the work area, they will require greater perimeter shielding to contain the critical workspace. With vertical and horizontal flow hoods that need to be Class 100 (ISO 5 or better), the air discharging from the HEPA filter must be inline with the hood or side walls of the support frame to eliminate turbulence. The air will become turbulent if non-moving air comes in contact with the moving laminar airflow. This is accomplished by having the media edge of the HEPA filter in line with the edge of the hood, or by putting in a secondary grill that diffuses the air so it is in shear with the hood’s surfaces. If turbulence exists, the resulting energy can flow along the vertical surface and draw in contaminated air from outside the bench.

On a horizontal flow bench this would exist on all four sides: hood, top, sides, and table top. On a vertical flow cabinet the air in shear should be on the sides and front. As previously mentioned, face shields help the laminar flow direct the clean air toward the work surface, prevent frontal turbulence, maintain higher exit velocities, and help the laminar flow fully develop.

Vertical flow hoods are available in many different configurations, including non-recirculation airflow, partial recirculating airflow, or recirculating with partial exhaust (odors can be controlled through charcoal filters or 100 percent exhaust). Exhausting units can be made of stainless steel or polypropylene, with specialty vertical flow cabinets almost exclusively made of polypropylene for trace metal analysis or work in which concentrated acids are used within the enclosure.

Biosafety cabinets are a type of clean bench designed for both product and personal protection, typically used with biological agents. They supply HEPA filtered air into the clean space, with a slight inflow at the front of the cabinet. The inflow is done in a manner that contamination does not get past the front grill, where a second HEPA filter cleans that air. Some units require this air also be 100 percent exhausted. Exhausting the HEPA filtered air from biosafety cabinets is a secondary measure of protection to ensure no biological agents within the bench enter the ambient space.

Location, location, location

The clean bench should be located away from obvious drafts, as well as areas where air velocity will exceed 100 ft per minute (the same airflow velocity coming out of the HEPA filter). If outside air is blowing directly toward the clean bench, it will blow into the unit and contaminate the space.

Clean benches are commonly used inside a cleanroom or other clean space. Persons with Class 100,000 (ISO 8) or Class 10,000 (ISO 7) cleanrooms will often utilize clean benches in critical areas to make them Class 100 (ISO 5), or even Class 10 (ISO 4). If the surrounding space is clean, the clean bench performs better, with significantly less particulate contamination for the HEPA filter to handle and less ambient contamination threatening to infiltrate into the work zone.

Additional considerations

The following lists other important factors to consider when specifying a clean bench.

  • Look for a UL listing on the assembled cabinet. Local code typically requires UL listing of products.
  • Request a speed control switch for the blower to adjust airflow velocity over time.
  • Make certain there is negative pressure around the HEPA filter.
  • Pay attention to where the clean bench will be installed to ensure that the location of the HEPA filter is compatible with future servicing needs.
  • Know whether the operator will be sitting or standing because this will impact the table height.
  • Confirm whether your process only requires particulate contamination control and at what level.
  • Confirm whether or not the operator needs protection from the process within the bench itself.
  • Confirm any physical restrictions you have when bringing the equipment into the space such as doors, hallways, and other equipment. If need be, order casters as part of the equipment.
  • Consider the workflow into, within, and out of the clean bench and how the bench is going to interface with the other operations.

Your cleanroom equipment supplier can help you determine which type of clean bench will best serve your application needs. Additional information is also available from the Institute of Environmental Sciences IEST-RP-CC002.2, ISO Standard 14644, and Federal Standard 209E.

Kevin Weist is president of Clean Air Products (Brooklyn Park, MN; www.cleanairproducts.com).

Potential challenges to consider when using a horizontal flow clean bench

  • The HEPA filter is located on the vertical rear side of the work surface and is susceptible to damage. A secondary grill is sometimes needed for filter protection.
  • A horizontal clean flow bench takes up more floor space because the filter is located behind the unit, rather than on the top as with a vertical flow cabinet.

What class is your clean bench?

How clean your bench needs to be is dependent upon the particular operation. It is not just the quality of the filter that makes a clean bench perform; it is also related to the airflow within the enclosure.

Using a HEPA filter does not guarantee that the clean bench interior will be Class 100 (ISO 5); you need the proper airflow within the bench.

Many clean bench users need to get to Class 10 (ISO 4); upgrading to an ULPA filter will typically help them reach this goal. Although an ULPA filter will be more expensive than a HEPA filter, the cost is relatively nominal considering the overall costs of a clean bench system.

How the HEPA filter seals to the cabinet

Many bench manufacturers utilize a negative pressure area around the HEPA filter to create a high pressure seal against the filter some distance away from the second gasket that seals against the cabinet. The space between these two gaskets is under negative pressure, such that if either of the gaskets should leak the air would flow away from the clean space and back toward the blower. This system eliminates troublesome gasket leaks and also serves to simplify future service to the unit.

By Hank Hogan

Contamination detection today is a technology not only of sight and sound but also of the ion. The latest advances incorporate laser, soundwave, and helium ion-based detection technologies-all now in use in semiconductor manufacturing, as device suppliers seek to spot and eliminate contaminants.


The two images above help to illustrate behavioral differences of a) a helium ion beam and b) an electron beam when hitting a sample. The helium ion beam’s heavier particles interact with a narrower surface region with very little scattering. Thus, the images do not suffer from sub-surface blurring effects that are common in SEM images. The result is that the helium ion microscope can produce images with higher resolution and more surface-specific information. Images courtesy of Carl Zeiss SMT.
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An example of the first of the three can be found in the offerings of Tiger Optics (Warrington, PA). The company’s latest analyzers measure airborne contaminants that impact the process. “For cleanroom air applications, we’re doing ammonia, hydrogen chloride, and methane,” says Lisa Bergson, Tiger Optics’ CEO.

The company’s Tiger-i ambient cleanroom air products are being tested now at semiconductor sites, with plans to release the analyzers later this year. The company’s products use cavity ring-down spectroscopy, in which a laser pulse bounces between mirrors and decays away. If an absorbing molecule is present, the ring-down time will be altered; by using varying wavelength pulses, different molecules can be detected.

Such instruments offer a wide dynamic range. According to Bergson, the detectors can spot contaminant concentrations as low as 200 ppt and as high as 20 ppm.

At Sonoscan (Elk Grove Village, IL), imaging is done with sound, making use of technology similar to ultrasound medical imaging. Using frequencies ranging from 10 to 400 MHz, the sound waves are fired into the subject part and the reflections captured.

Steve Martell, Sonoscan’s manager of technical support, says the technique offers the ability to peer inside a packaged part and see how all the different layers are adhering to one another, which can be vital information. “You want to check out the parts once in a while to make sure you don’t have any contamination that has shown up that is now causing a disbond or improper bonding to materials.”

The company has recently added the technology to look at bond-line thickness. This inspection can be done in conjunction with contamination checks.

Another technology comes from the ALIS business unit (Peabody, MA) of Carl Zeiss SMT, which has developed a first-of-its-kind helium ion-beam microscope.

The helium ions penetrate the surface of a material, giving rise to secondary electrons and backscattered helium. The backscattered ions act as a nanoscopic probe of the material and so provide more than a simple image. Says Clarke Fenner, vice president of business development for ALIS, “When you look at contamination or do a defect review, this gives you the ability to differentiate between these different materials and potentially determine what the contaminants are on the nanoscopic level.”

Fenner reports that one of the first two systems shipped went to a chipmaker to use for failure analysis.

Facility-wide ionization monitoring and control systems maintain yield and productivity

By David Feindel, MKS, Ion Systems

Ionization is a facilities requirement that is critical for the maintenance of production yield and output. Unfortunately, it can be very difficult to monitor and control. Typical systems include hundreds of ceiling emitter air ionizers scattered throughout cleanroom areas in semiconductor, hard disk drive, liquid-crystal display (LCD), medical device, MEMS, or nano facilities. Emitters can be connected to six or more controllers, and settings and alarm levels can vary from area to area within a facility. The emitters and ancillary equipment are usually mounted in remote places where they operate without intruding on the process. As a result, an ionization system alarm may not be noted until manufacturing yield or throughput drops, well after the problem was first detected by the ionizer or controller.

To improve the monitoring and control capabilities of ionization systems, the industry is shifting to the use of facility-wide software packages that continually monitor the performance of ionizers and provide appropriate alarms for timely corrective action.

Room ionization systems

Cleanroom ionization systems are designed to eliminate any static charge buildup on the surfaces within a facility by flooding the air with both positive and negative ions. Charged surfaces attract ions of the opposite polarity and are rapidly neutralized. Leading-edge manufacturing facilities such as those for semiconductor front-end, hard disk drive media, and flat-panel display arrays require particle-free environments since particles even 50 nm or 100 nm in size can cause a yield loss. By neutralizing the charge on product surfaces, ionization systems prevent airborne particles from being attracted to and adhering to the product. A second function of neutralizing static charge is the prevention of electrical damage in the product. In-process semiconductor wafers, reticles, LCD arrays, and other products can suffer direct or latent damage from electrostatic discharge (ESD) events resulting from charge accumulating on devices. ESD events can also cause process and tool downtime.


Figure 1. A magnified view of a dirty emitter point, causing reduced ion output. Photo courtesy of MKS, Ion Systems.
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A cleanroom ionization system typically consists of 50-1,000 ionizers, mounted to the ceiling just below the HEPA filters. One ionizer typically covers 20-60 sq. ft. (approximately 2-6 m2) of floor space. Groups of up to 80 ionizers are connected to a controller, which is usually mounted on a wall in the fab. Prior practice in these systems used a 4-20 mA loop circuit to connect each controller to a central monitoring computer, called a factory monitoring system, or FMS. The presence of this signal indicates that a warning in the system has been triggered by a controller or the ionizers connected to it. This arrangement makes it difficult for the responsible engineer to detect an ionization alarm and to identify what equipment or procedures would be required to fix it.

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An examination of the facilities history within a highly dynamic environment such as an operating fab shows that numerous situations occur that can defeat the remediating action of an ionization system. These include accidental turn off/disconnect of the ionizers, damaged interconnect cables as a result of other facility work, inappropriate operating settings, or temporary or permanent system damage from process equipment electrical interference (EMI). The most common fault lies in a poorly monitored and maintained system that suffers reduced ion output over time due to a buildup of contaminants on the emitter points from the presence of particles in the environment.

Monitoring the system

A good monitoring system will observe ionization activity. However, it can, and should, do more. Key capabilities of a monitoring system should include the following.

Providing a graphical map of the system. This allows maintenance personnel to quickly pinpoint exactly where alarms or other events occur, so they can rapidly fix the issue. The ideal system will provide a graphical summary view of system status, as well as easily understood tools such as panning and zooming for drilling down on suspected problems or issues.


Figure 3. Map of the ionization system magnified to display a bay. Image courtesy of MKS, Ion Systems.
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Remote monitoring and control capability. Process and maintenance engineers want the ability to instantly see the entire system’s status at a glance. Ideally, this information can be viewed outside the cleanroom area, and even in other buildings (firewall and IT policies permitting). Being able to remotely view a detailed system status also allows the manufacturer’s support technicians to better diagnose problems.

Providing helpful information on what the problem is. This may take the form of detailed error messages, a display of a parameter’s history over the last several days, or the identification of the probable cause of problem (i.e., next to a recently installed tool).


Figure 4. A detailed view showing the status of all emitters connected to a controller. Image courtesy of MKS, Ion Systems.
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Error notification. During initial installation, users often ask that the system be configured to report all errors as soon as they are detected. After the installation, however, users realize that the ability to filter the errors that trigger notifications is important. For example, the user probably does not want to receive a communications error on its first occurrence, but rather only if the same attempted communication fails consecutive times. Users also find it beneficial to set up filter systems for clearing errors and escalating notifications.

Ionizer control. Users need the ability to determine the values for the various ionization parameters of each emitter and to change them where appropriate. Normally, ionization settings should not be changed unless measurements are made using a charged plate monitor (CPM) at the site of the ionizer. However, it can be useful to be able to remotely turn off the ionization in a bay while a tool is being moved in, to change ionization settings as a result of fab-wide environmental changes, or to place an alarming ionizer in standby mode.

Managing scheduled maintenance. The ionizer system must be able to monitor performance over elapsed time in order to issue preventative maintenance (PM) notifications or, if the ionizers in a particular bay are becoming less efficient, to note that they are approaching a needed cleaning cycle.

Monitoring the hardware in the ionization system, providing status updates at user-set intervals. Change occurs slowly in ionization systems and there is typically no need for historical, minute-by-minute records. User-set data logging periods allow system managers to make an intelligent tradeoff between tracing problems with the system and sifting through unchanging data logs.

System scalability. The software needs to accommodate smaller installations (for example, 20 to 30 ionizers in one room) as well as multi-facility installations, with 1,000+ emitters in several buildings.

Monitoring electrostatics in the environment. As manufacturing processes become even more sensitive, using a monitoring system that can also monitor ESD events, grounding, and other electrostatics-related conditions makes sense. For example, it is now possible to detect voltage on wafers as they pass through the front end of a process tool. Measuring this voltage and adjusting the ionization dynamically to compensate for its presence improves the process.

A high-end, industry-standard database. Monitoring and controlling a key manufacturing system requires highly reliable components, including an underlying database engine that logs data over many months or years and allows users to retrieve the data quickly, easily, and without error. The best systems will use a Microsoft® SQL Server or equivalent database.

The payback

The presence of a fully capable cleanroom ionization monitoring and control system-whether as part of an initial install or as a retrofit to an existing system-ensures the electrostatic quality of an environment. Such systems are of immediate and quantifiable benefit to facilities and maintenance staff, allowing them to make rapid, fact-based evaluations of the criticality of any ionization problems and to determine the most effective solutions to these problems. The best systems deliver a concise picture of the ionization equipment and conditions in a cleanroom to the manager’s desk, often eliminating the need for cleanroom entry for problem evaluation. The reduction in the number of ESD events that can be achieved by using a properly functioning ionization system can improve facility yield through reductions in tool disruptions and shutdowns.

As the design and fabrication processes for high-tech products become ever more complex, facility-wide ionization monitoring and control systems that ensure proper static control are a requirement for maintaining yield and productivity.

David Feindel is vice president of product marketing at MKS, Ion Systems (Alameda, CA; www.mksinst.com), responsible for all phases of product performance-from development to release to market. He holds a BS in management science and an MBA.

Particles


September 1, 2007

compiled by Carrie Meadows

Omnetics completes cleanroom build
Omnetics Connector Corporation, a manufacturer of miniature high-reliability connectors for OEMs, has completed construction of a 340-sq.-ft. cleanroom within its Minneapolis manufacturing plant. The cleanroom will be used for cleaning, testing, and packaging products, as well as providing custom assembly for medical applications such as cochlear implants. The company expects lead times for both standard and custom products to decrease as a result of having all critical production stages in-house.

Proven Process Medical Devices relocates

Proven Process Medical Devices, a contract R&D and manufacturing firm specializing in electromechanical medical devices and equipment, has moved its U.S. headquarters to a new 43,000-sq.-ft. facility in Mansfield, MA. The location represents an 80 percent increase in total facility area over the company’s former location in East Walpole, MA; the new research, engineering, and manufacturing space includes a state-of-the-art Class 10,000 (ISO 7) cleanroom.

Asia-Pacific to grab one-third of IC market by 2011

In its latest report on worldwide IC sales, Arizona-based IC Insights says that Asia-Pacific companies have grown from holding only 2 percent of the IC market in 1985 to 26 percent in 2006. The Asia-Pacific IC supplier segment is primarily composed of Taiwanese, South Korean, and Chinese companies. Because of the large growth forecast for the foundry industry, a segment in which many Asia-Pacific companies are heavily involved, IC Insights believes that the Asia-Pacific companies will continue to gain market share and represent almost one-third (32 percent) of worldwide IC sales in 2011. Japanese market share dropped to 17 percent last year, while European companies have held strong with 8-10 percent of the market; companies headquartered in the Americas have consistently held about half of the sales.

Bosch closes Pharmatec deal

The Bosch Group has acquired Pharmatec GmbH, a leader in pharmaceutical plant engineering (Dresden, Germany) with a focus on hygienic and sterile process technologies, from Fresenius ProServe GmbH. Part of this transaction is Pharmatec subsidiary Schoeller-Bleckmann Medizintechnik Ges.m.b.H based in Ternitz, Austria. Bosch says the acquisition of Pharmatec and Schoeller-Bleckmann Medizintechnik will complement its existing products in the pharma packaging technology sector. Financial terms of the transaction were not disclosed.

CoorsTek polymer USP Class VI-approved

CoorsTek, a provider of technical ceramics and producer of PTFE-based polymer seals and components, has received USP Class VI approval for its advanced Tetralon 240 polymer used in pharmaceutical and biomedical applications. The material is primarily used in high-performance seals and bearings where long component life and low friction are critical. Product testing revealed Tetralon 240 polymer features a low coefficient of friction (0.15 to 0.2 @ 33.3 psi, 150 FPM), durable tensile strength (5,500 psi using ASTM D4894 test), and a low deformation under load at 8.0 percent (ASTM D621).

Using new steamer design, silicon oxidation process shows up to 20 percent improvement in oxide uniformity

By Jeffrey Spiegelman, RASIRC

Oxidation of silicon is a common and frequent step in the manufacture of integrated circuits (ICs). The success or failure of the IC manufacturer often depends on the ability to grow a uniform oxide film quickly and repeatedly. Water vapor is commonly used to grow oxides; a new steamer design replaces water bubblers, direct water injection, and pyrolytic torches for the delivery of water vapor into oxidation processes.

Starting with deionized (DI) water, the steamer uses a non-porous hydrophilic membrane that selectively allows water vapor to pass through it. Membrane selectivity is significant with water molecules passing through it 1 million times faster than nitrogen molecules. In the vapor or steam phase all other molecules are greatly restricted, so contaminants in water such as dissolved gases, ions, total organic carbons, particles, viruses, bacteria, pyrogens, and metals can be removed. Total metals have been verified to less than 10 ppt.1

Test results were collected from installations at three different fabs. Each steamer installation replaced a different form of water vapor delivery. Expected benefits were lower cost, improved safety, and reduced film contamination. These expectations were met, and unexpected improvements in uniformity and growth rate were also reported during wet thermal oxidation of silicon wafers.

This article will review the thermal oxidation process for silicon, present the field results for the steamer installations, and then discuss the results.

Thermal oxidation2

Oxidation is a process used in wafer fabrication. The goal of oxidation is to grow a high quality oxide layer on a silicon substrate. During oxidation, a chemical reaction between the oxidants and the silicon atoms produces a layer of oxide on the silicon surface of the wafer. It is often the first step in wafer fabrication and will be repeated multiple times throughout the fabrication process.

Oxidation takes place in an oxidation tube. During the reaction, silicon reacts with oxidants to form silicon oxide layers. Typical operating temperature is between 900° and 1,200°C. The oxide growth rate increases with temperature. Generally, this technique is used to grow oxides between 60 and 100,000 angstroms thick.

Thermal oxidation of silicon is divided into two classes-dry and wet.

  • Dry oxidation

Si (solid) + O2 (gas) → SiO2 (solid)

  • Wet oxidation

Si (solid) + H2O (gas) → SiO2 (solid) + 2H2

Dry oxidation. During dry oxidation, dry oxygen is introduced into the process tube where it reacts with silicon. Dry oxidation is a slow process that grows films at a rate between 140 and 250 angstroms/hour. It is only used in industry to grow thin oxides (less than 1,000 angstroms).

Wet oxidation. During wet oxidation, water vapor is introduced into the heated oxidation tube. Because water molecules are smaller in size than oxygen molecules, they diffuse faster in silicon dioxide and the oxide growth rate increases. The wet oxidation growth rate is 1,000 to 1,200 angstroms/hour, so wet oxidation is the preferred method to grow thick oxides.

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As a general principle, the amount of silicon consumed in the oxidation reaction is 45 percent of the final oxide thickness. For example, growing 10,000 angstroms of oxide consumes 4,400 angstroms of silicon.

Linear parabolic model

The kinetics of SiO2 growth occurs in three steps. First, the oxidant (H2O or O2) reacts with silicon atoms, then silicon atoms are consumed by the reaction, and finally a layer of oxide forms on the silicon surface.

The linear parabolic model developed by Deal and Grove3 demonstrates how silicon dioxide is grown on a silicon substrate during oxidation under both wet and dry conditions. The model identifies and defines two different stages in the oxidation of silicon: linear and parabolic.

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Linear (first) stage. As the first phase in oxide growth, the linear stage refers to the chemical reaction resulting from the direct contact between the silicon and the oxidants at the surface of the wafer. The reaction is limited by the number of silicon atoms available to react with the oxidants. For approximately the first 500 angstroms, the oxide grows linearly with time. From that point on, the reaction rate begins to slow down as a direct result of the silicon dioxide layer covering the silicon atoms. As the silicon dioxide layer grows, it eventually prevents the oxidants from coming in direct contact with the silicon atoms and the parabolic stage of oxidation begins. The reaction of the oxygen at the silicon/silicon dioxide interface limits the oxide growth in this stage.

Parabolic (second) stage. The parabolic stage of oxidation begins when approximately 1,000 angstroms of silicon dioxide have been grown on the silicon substrate. At this point, the silicon atoms are no longer exposed to the oxidants and the oxidants begin to diffuse through the silicon dioxide in order to reach the silicon. The oxidation of silicon during this stage occurs at the silicon/silicon dioxide interface. As oxidation continues, the silicon dioxide layer thickens, and the distance the oxidants must travel to reach the silicon increases. The oxide growth rate is limited by the diffusion of the oxidants through silicon dioxide.

The details of the Deal-Grove Model are left to the reader. To summarize the portion relevant to our discussion, the growth rate depends on the concentration of oxidant at the oxidized surface to drive the oxidant through the oxide layer to get to the unoxidized silicon surface.

Henry’s Law states that the concentration of an oxidant in the solid is proportional to the partial pressure of the oxidant in the surrounding gas. Increasing the water vapor pressure or oxygen pressure in the process gas environment will increase the oxidation growth rate.

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An increase in the water vapor pressure will directly increase the oxidation rate. Many researchers have reported increased growth rate with increased water pressure. Choe et al.4 reported a fourfold increase in aluminum arsenide (AlAs) oxide growth rate with increased water vapor pressure and no carrier gas at 440°C.

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Figure 3 shows how an increase in temperature or pressure increases the growth rate. The oxide thickness increases with both pressure and temperature.

In practice, there are limitations to both temperature and operating pressures. Operating temperatures are kept below 1,200°C due to limitations of the equipment and thermal effects on materials. Although diffusion furnaces running above atmospheric pressure have been built, they are far more dangerous and become significantly more expensive to purchase and operate. Oxidation furnaces are generally run at atmospheric pressure.

Steamer test results

Test steamers were installed at three separate locations. All three installations were horizontal furnaces that were dedicated to wet thermal oxidation. The first steamer installation was on a 6-inch furnace tube that replaced a water bubbler that used oxygen as a carrier gas. The second steamer was installed on an 8-inch furnace tube and replaced a direct water injection system that used an oxygen carrier gas to purge the vaporizer. The third installation was on a 300 mm furnace and replaced a pyrolytic torch that generated water vapor from combustion of oxygen and hydrogen. The elimination of hydrogen from the process allowed the user to expand production and still remain within local fire ordinances. All customers expected the same or better film quality but did not expect a change in oxidation growth rate or process uniformity.

Process recipe temperatures and run times were kept constant. The only changes made were the elimination of oxygen and/or hydrogen gas and installation of the steamer. Total amount of steam supplied was initially the same as the previous technology and then adjusted to maximize performance.

Growth rate

Installation 1. The furnace was operated at 1,000°C. Initial results from replacing the bubbler with the steamer generated a consistent improvement of greater than 16 percent.

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The recipe was then changed to eliminate the oxygen flow of 1 slm. Wafers were loaded at three locations within the tube. Run time was 104 minutes. Eliminating the oxygen purge improved the growth rate by 7 percent on 50,000 angstrom film.

Installation 2. At the second installation, the steamer was attached to an 8-inch horizontal furnace. The steamer replaced an existing DI water direct injection system running at 8 grams/minute. The oxygen purge through the injector was also eliminated. Multiple lots of 130 wafers were run through the furnace for different periods of time. Every fifth wafer was measured to get an average growth rate along the furnace tube and from run to run. The results were compared to film grown with water injection vs. the steamer.

Thin films reported better than 20 percent increase in growth rate. This rate slowed to more than 5 percent at thicknesses greater than 3,000 angstroms.

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Installation 3. The 300 mm furnace was operated at 900°C. The pyrolytic torch was replaced with a steamer. Flow rate was 30 slm of steam. Time to grow the 1,000 angstrom film was reduced from 32 minutes to 28 minutes, representing a 7 percent increase in growth rate.

Uniformity

Installation 1. A 6-inch horizontal furnace was operated at 1,000°C. Wafers were loaded at three locations within the tube. Run time was 104 minutes. By eliminating the oxygen and increasing the water vapor flow rate, the non-uniformity across the tube decreased from ±3% to ±0.2 percent.

Installation 2. Three separate runs were made of 8,000 angstrom films. Previous customer requirements were ±5 percent. Before steamer installation, oxide thickness uniformity often exceeded the acceptance criteria with film thickness failing to meet 95 percent of target. This required measurement of each wafer and reworking a partial load. The tighter uniformity eliminated rework for definitive oxide thickness.

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Installation 3. Initial data was collected on the 300 mm tool. The steamer was moved from the 300 mm tool to the 8-inch furnace for additional tests. Uniformity was average 995.410, min 992.63, max 999.43, range 6.809, std. dev. 3.325, and wafer uniformity 0.342000.

Increased growth rate with increased partial water vapor pressure

Users of the steamer demonstrated increased growth rate while keeping operating pressure fixed at atmosphere and increasing the partial pressure of water vapor. Similar increases in growth rate with increasing water vapor pressure had been reported by Geib et al.5

While increasing water vapor flow rate seems obvious to improve growth rates, technical difficulties interfere with increasing the actually quantity of delivered water vapor. For bubblers, the water cannot be heated near boiling or uncontrolled flow will result. The carrier gas flows needs to be increased to increase the delivery rate, which can then slow the diffusion of water vapor to the surface. With direct liquid injection systems, increasing flow rate leads to incomplete vaporization. This increases micro-droplet formation, which increases non-uniformity and ionic contamination on the wafer. Torches become larger and the thermal load from pyrolytic combustion of hydrogen and oxygen becomes more difficult to handle. There is also an increase in operating cost and safety issues.

Three different facilities using three different methods-a bubbler, vaporizer, and pyrolytic torch-all confirmed that a reduction in background oxygen gas and an increase in water vapor pressure resulted in an increased oxide growth rate. This increase in water vapor pressure agrees with the Deal and Grove Model for oxidation.

When the water vapor pressure is increased, the oxide growth rate is increased. According to the model of Deal and Grove, the growth rate of the oxide layer is directly related to the effective diffusion coefficient of the water molecules into the oxide layer and the equilibrium concentration in the immediate area. When a carrier gas is used to deliver water vapor, the carrier gas molecules generate a partial pressure. This partial pressure lowers the partial pressure of water vapor and slows the diffusion of water into the oxide film. The result is lower driving force and slower growth rate. For a given temperature and process pressure, oxide growth rates are fixed if the gas ratio is also constant. However, for a given operating temperature, this growth rate is not maximized until the water vapor pressure is equal to 100 percent of the operating pressure.

Localized effect and uniformity

At the gas entrance to the furnace tube, there is a ratio of partial pressure of oxygen to water vapor. As the water molecules travel toward the exit of the tube, they are absorbed into the oxide film at a much faster rate than the oxygen molecules. The oxide growth results in the gradual reduction in water molecules relative to the oxygen molecules. This localized reduction in water molecule concentration slows the available oxidation reaction and the growth rate as the exit of the furnace is reached, leading to a typical slower growth at the exit of the furnace and front-to-back non-uniformity as can be seen in the uniformity results from Installation 1.

As long as oxygen is part of the process recipe, the partial pressure within the furnace tube will not be uniform. By eliminating the oxygen gas, the water vapor pressure stays relatively constant and film uniformity improves across the chamber.

Conclusion

Replacement of previous water vapor delivery systems with the new steamer design resulted in significant increase in oxide growth rate and improvement in uniformity throughout the furnace.

For a given temperature and process pressure, the oxide growth rate is not maximized until the water vapor pressure is equal to 100 percent of the operating pressure.

If oxygen makes up part of the process recipe during wet oxidation, it will slow the overall growth rate by reducing the water vapor partial pressure. The oxygen gas will also lead to non-uniform growth throughout the furnace tube, since as the water is consumed from front to back of the furnace, the partial pressure of oxygen increases, and the partial pressure of water decreases. This difference in water partial pressure leads to variability in the oxide growth rate and non-uniformity throughout the furnace tube.

Jeffrey Spiegelman is president and CEO of RASIRC, a company specializing in liquid purification and delivery products.

References

  1. J.J. Spiegelman, R.J. Holmes, “Alternative Method and Device to Purify and Deliver Water Vapor,” SPWCC, February 2006.
  2. J. Salzman, “Microelectronic Processing Oxidation,” Microelectronics Processing Course Presentation,
  3. B.E. Deal, A.S. Grove, J. Appl. Phys. 36, p. 3770, 1965.
  4. J.-S. Choe, S.-H. Park, B.-Y. Choe, H. Jeon, “Letter to the Editor: Lateral Oxidation
    of AlAs Layers at Elevated Water Vapor Pressure Using a Closed Chamber System,” Semiconductor Sci. Tech. 15, pp. L35

On October 16, 2007, at 1:00pm EST, CleanRooms magazine editor-in-chief John Haystead will moderate the third in a series of live, interactive webcasts-“USP <797>: Implementing Practical & Available Solutions”-which will host a select mix of contamination control solution providers.

USP Chapter <797>, “Pharmaceutical Compounding: Sterile Preparations,” sets forth standards, guidance, and examples for compounding sterile preparations (CSPs), and identifies the tools, protocols, and environmental controls that must be in place to safely perform sterile compounding operations.

Each presenter will have an opportunity to demonstrate their knowledge and understanding of individual aspects of USP <797> and how their existing technology, expertise, and current products can be effectively applied to meet these requirements. Registrants will have an opportunity to question the presenters specific to their own compounding operations, and any unique challenges and concerns they may have.

Cleanroom Lighting


September 1, 2007

Because there are no formal standards for lighting in cleanrooms, contractors and operators must have a thorough understanding of the different types of lighting, fixtures, and installation options available and consider which one will best suit the level of cleanliness required in their critical environments. Here are a few supplier options.

Compiled by Carrie Meadows

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Lighter-weight fixture offers flexible ceiling placement
The Bio-Seal is the most technically advanced grid and flange cleanroom troffer available. It is certified for Class 100 (ISO 5), IP66, NSF, and Class 1 Division 2 spaces. The standard seam-welded aluminum body radiates lamp and ballast heat to provide extended transformer life and higher lamp lumens. Its 60 percent lighter weight does not burden a sheet rock ceiling. The one-piece gasket system is dust tight and withstands 26 gpm hosedown without leakage. The fixture can easily provide 30,000 lumens from 6-T5HO lamps. Options include SS doors and housing, surface mounting, and top access re-lamping.

Guth Lighting
St. Louis, MO
www.guth.com

Standard and custom cleanroom lighting systems

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Choosing cleanroom lighting fixtures that won’t leak, introduce toxicity or corrosion, add excessive heat, or create potentially unsafe conditions is crucial to each cleanroom environment. Innotech Products offers a quality line of cleanroom lighting such as laminar flow-through, tear-drop, and contaminant-proof sealed housing fixtures, as well as top access, recessed, surface, corner, and UV-shielded lights for clean applications. The fixtures come in standard and custom sizes to fit virtually any ceiling system style. To speak to a cleanroom specialist regarding these and other cleanroom needs, call (888) 270-0458.

Innotech Products
Minneapolis, MN
www.innotechprod.com

NSF-certified lighting suitable for harsh environments

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LDPI Lighting’s 376 Series wet/damp fluorescent light fixtures have recently been tested and certified by NSF (National Sanitation Foundation) International to NSF/ANSI Standard 2. The fixtures are designed for use in a variety of areas where harsh conditions exist, such as food and beverage processing facilities, packaging and distribution centers, refrigeration rooms/freezers, cleanrooms, and other areas where extra sanitation precautions are needed. The lights feature a poured-in-place polyurethane gasket and latch that provides continuous positive gasket contact while sealing enclosures from the most hostile environments. Durable components include stainless-steel mounting hardware and a corrosion-resistant non-metallic enclosure. A unique mounting system, which eliminates the need for drilling holes through the housing, reduces installation time. Mounting brackets are designed for narrow and standard lamp housings, and an optional 45° mounting bracket is available.

LDPI Lighting, Inc.
Eau Claire, WI
www.ldpi-inc.com

Light-emitting diode bulbs replace direct incandescent systems

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LEDtronics’ latest generation of PAR20 LED short-neck light bulbs replace direct incandescent bulbs, combining advanced light-emitting diode (LED) technology, standard 25 mm Edison screw bases, and a light-optimizing design to produce vivid light. The LED bulbs are available in three light-emitting angles: 15°, 20°, and 22° and in 120 V AC. Other voltages such as 12 to 240 V AC or DC are available to qualified customers. They are well suited to small spotlighting tasks in track or recessed lighting fixtures or high-hat ceiling spotlights. With a power draw of only 2.5 W, energy savings add up over time. Standard colors available are Warm White and XWarm White (3,000 K), Cool White (7,000 K), Super Red (633 nm), and Aqua Green (525 nm).

LEDtronics, Inc.
Torrance, GA
www.ledtronics.com

During the American Society of Heating, Refrigerating and Air-Conditioning Engineers’ (ASHRAE) annual meeting in Long Beach, CA, Purafil’s technical director Chris Muller was honored with a Distinguished Service Award (DSA). Muller, a 12-year member of the organization, serves as a Distinguished Lecturer and as chair of the ASHRAE Standard Committee 145P, which was charged with the task of engineering the ASHRAE Standard 62.1-Ventilation for acceptable indoor air quality.


Purafil’s technical director Chris Muller (right) receives a Distinguished Service Award from 2006-2007 ASHRAE president Terry E. Townsend, PE (left). Photo courtesy of Purafil, Inc.
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In addition to these ongoing responsibilities, Muller remains involved within the organization as a voting member of several committees and as a co-author of the ASHRAE Standard 62.1-2004 User’s Manual. He is also a frequent contributor to CleanRooms magazine.

Muller says that his role at Purafil, which involves managing the technical services group and keeping abreast of new technology for air cleaning-“both complementary and competitive”-has been greatly enhanced by his involvement with the industry organization “based on the far-reaching effects that some of the work I’m doing will have.” He continues, “As chair of [ASHRAE’s Standard Projects Committee (SPC)-145], I’m responsible for the committee that is writing the standards that could be applied nationally and internationally to assess the performance of chemical filter systems.”

Altogether, nearly 60 members of ASHRAE were recognized at the plenary session during the annual meeting. Founded in 1894, the society continues to influence the progress of heating, ventilation, air conditioning, and refrigeration technology through its approximately 50,000 members with expertise in energy efficiency, indoor air quality, codes and standards, and guidance for a safe environment during extraordinary incidents. For more information regarding ASHRAE and the award recipients, visit www.ashrae.org.

New Products


September 1, 2007

Compiled by Carrie Meadows

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Dry-block calibrator
The new JOFRA™ ATC-125 Ultra Cooler from AMETEK T-Americas is the first dry-block calibrator capable of reaching -90°C and also is able to reach temperatures as high as +125°C, for a total temperature range of 215°C. The ATC-125 achieves cryogenic temperatures quickly, quietly, and efficiently through its patent-applied-for Free Piston Stirling Cooler (FPSC) technology. Together with a special heating element for elevated temperatures, these technologies allow users to perform five-point calibrations up to five times faster than an equivalent liquid bath. The calibrator is supplied with mains power variance immunity (MVI) technology, which avoids stability problems by immediately identifying and correcting variations in the mains input voltage in order to maintain a constant energy flow to the temperature block. The ATC-125 is engineered for use in laboratory and industrial environments for pharmaceutical, medical, food, food ingredients, hospital, and other applications.

AMETEK T-Americas
Albany, NY
www.jofra.com

Optical gas detection system

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The ChemLogic 8 is a continuous eight-point gas detection system targeted for the detection of low-level toxic and corrosive gases. The ChemLogic 8 has an optimized flow system that draws samples 250 ft at 2.5 LPM. This system offers a built-in touch-screen and a CF flash memory that records event history. It incorporates technologically advanced optics, which reduces maintenance. Improved technology has reduced the initial investment to 50 percent less per point and the cost of ownership is 36 percent less than related products in the field.

DOD Technologies, Inc.
Crystal Lake, IL
www.dodtec.com

High-pressure controller for particle counting

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Designed using the latest technology in high-pressure gas components, the Lighthouse Worldwide Solutions HPC 1100 allows attachment of Lighthouse 0.1 μm particle counters to high pressure (30-150 psi) inert gas systems. This provides monitoring capability for process gases, a possible source of contamination. The HPC 1100’s low audible noise and small footprint allow installation in areas where diffusers were thought impractical. The HPC 1100 zero counts in less than 5 minutes and does not induce spurious or random 0.1 μm counts due to oscillations as other designs can. The HPC 1100’s stainless steel design is rugged, reliable, and requires almost no routine maintenance and never requires any calibration. During normal operation, no inert gas is wasted; 100 percent of the gas supplied is used for the sampling process.

Lighthouse Worldwide Solutions
Fremont, CA
www.golighthouse.com

Laminar flow workbenches

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Laminar flow workstations provide dust- and particle-free work areas for sensitive testing and assembly. IAC Industries’ laminar flow industrial workbenches are recommended for any Class 100 (ISO 5) area. The workbenches are offered in both vertical- and horizontal-flow versions. Horizontal-flow workbenches provide the best product protection since the individual using the workbench is always downstream of the work area. The laminar flow workstations include 90 fpm air velocity, HEPA filters to capture particles as small as 0.3 μm, easy-access pre-filters, magnehelic gauge to monitor static air pressure, fluorescent lighting, and cleanroom-sealed work surfaces. Fans are centrifugal, direct-drive with static capacity up to 1.2 inches W.G. at rated flow and are mounted on rubber isolators for smooth, quiet operation. A variable-speed control allows users to adjust airflow.

IAC Industries
Brea, CA
www.iacindustries.com

Ultrafiltration cassettes for bioprocessing

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Biopharmaceutical manufacturers require efficient, high-throughput ultra-filtration technologies to handle higher protein concentrations. To address this need, Pall Corporation introduces the new Omega™ T-Series Membrane Cassettes. The cassettes are constructed with high-performance materials that reduce extractables to reduce the amount of rinsing volumes required prior to cassette use and ensure effective mass transfer of proteins, which is critical to keeping costs manageable in drug production. Pall also introduces single-use Minimate™ II encapsulated membrane cassettes. The Omega cassettes incorporate Pall’s high-yield Omega membranes and a new polypropylene screen to increase processing flux rates and product recovery. Materials of construction chosen for the Omega T-Series cassettes ensure a low level of extractables.

Pall Corporation
East Hills, NY
www.pall.com

Bulk gas purification system

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The Entegris Aeronex® Gas Purification System (AGPS) Z2 series brings advanced contamination control technology to bulk gas purification for dry and immersion-based lithography tools. As part of the Entegris Clarilite solution, the AGPS will also help increase protection against reticle haze. The AGPS is designed to meet the capacity requirements of current as well as next-generation tools, which are expected to require more than four times the current volume of gas. Using multiple purifier beds working in parallel to maintain a continuous flow of pure gas, the beds automatically regenerate in sequence to help ensure optimal removal of targeted molecular contaminants. The new Z2 purification technology provides outlet purity in sub-ppt levels and reduces environmental impact because it is longer lasting than other media.

Entegris, Inc.
Chaska, MN
www.entegris.com

Tabletop cleanroom robot

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KUKA Robotics Corporation has introduced its KUKA KR5 Sixx CR six-axis cleanroom and splash-proof robot. The Sixx robot family was designed for customers with applications requiring six-axis functionality for long-reach tasks. Due to its small size, the robot can be integrated easily without unnecessary space consumption and satisfies numerous requirements of cleanroom applications. When combined with the company’s PC-based control platform, the robot will give customers a user-friendly pick-and-place automation tool for extreme cleanroom requirements. With a 650 mm reach and payload capacity up to 5 kg, the KR5 Sixx CR meets the appropriate ISO and DIN standards for cleanroom operation and is compliant to ISO 5 and Class 100 standards.

KUKA Robotics
Clinton Township, MI
www.kukarobotics.com

Vacuum pump traps

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A new series of replaceable filter elements for the full line of MV Products vacuum-pump inlet traps, which target specific types of process byproducts, includes four new types: a proprietary activated carbon media for ammonia vapors, SodaSorb® for HCL, Resisorb® for mercury vapor absorption, and activated charcoal for organics. Utilizing 2.75-inch diameter by 4.5-inch or 90-inch tall filter element shells, they are suitable for applications ranging from 25 to 1,000 CFM and may be used in any combination. MV Filter Elements are designed to fit the Posi-Trap®, which comes in sizes that hold from one to four filter elements, and the MV Multi-Trap® featuring a large knockdown stage and up to six separate stages, each holding multiple filter elements. Other filter elements offered include stainless steel and copper gauze, molecular sieve, activated alumina, and pleated polypropylene.

MV Products, a division of Mass-Vac, Inc.
North Billerica, MA
www.massvac.com

Abrasion-resistant nitrile gloves

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Sempermed® now offers SemperGuard® industrial nitrile powdered and powder-free gloves as an alternative to natural rubber latex. SemperGuard gloves are suitable for individuals who are at risk of becoming sensitive to natural rubber latex. Nitrile gloves are made from a synthetic polymer exhibiting rubber-like characteristics when vulcanized; SemperGuard gloves are designed to provide the fit, feel, tensile and tear strengths, and other properties of natural rubber latex gloves. The micro-rough textured surface enhances tactile sensitivity with increased gripping characteristics, and electrostatic charges are effectively dissipated. Because of their resistance to abrasion, nitrile gloves slough off fewer particulates, resulting in reduced potential for contamination in critical manufacturing environments. The gloves feature a high solvent resistance and comply with FDA 21 CFR Guidelines and Agriculture and Agri-Foods Canada Requirements, making them appropriate for food, food processing, pharmaceutical, and laboratory applications.

Sempermed USA, Inc.
Clearwater, FL
www.sempermedusa.com

Aseptic filling machine

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Fast, accurate dispensing of pharmaceutical and biotechnology serums and fluids, easy product changeover, elimination of cross-contamination, and simplified aseptic filling and cleaning validation are possible in a seamless process with the new Disposable Filling Machine™ available from Flexicon America Inc. The machine combines ready-to-use, fully disposable DAFPA™ (disposable aseptic fluid path) assembly with Flexicon Peristaltic Technology. A gamma-irradiated assembly is mounted onto a stand and threaded through the peristaltic pump head and secured into a disposable filling needle. The closed, disposable DAFPA system dispenses the fully contained product in a gentle transfer through sterile tubing. The used product bag, tubing, and filling needle are simply discarded and new components are set into position on the machine.

Flexicon America Inc.
Burlington, VT
www.flexiconamerica.com

Grounding monitors for electronics assembly

A new family of monitors from 3M provides complete surveillance of grounding in electronics assembly, particularly for soldering irons and process tools. The 3M Down to Earth brand Monitor Series, which features devices smaller than a cell phone, instantly alerts workers of a problem as it occurs, allowing corrective action to restore grounding and prevent further damage to sensitive electronics. The series consists of the Iron Man™, which monitors circuit boards that can be damaged by improperly grounded soldering irons, tweezers, and other hand tools; the Iron Man™ Plus, which adds monitoring of the worker’s wrist strap and mat; the Ground Man, which monitors process tools in the electronics manufacturing and semiconductor environments; and the Ground Man Plus, which adds monitoring of the operator’s wrist strap.

3M
Austin, TX
www.3m.com/electronics

Capped single-tip swab

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Qosina introduces a new swab with cap (Part # 17647). The 6-inch long, single-use cotton-tipped applicator is well suited to collecting contamination-free samples and specimens. The polypropylene vented cap slides down the wood shaft to allow easy sampling, then slides back to cover the swab head with a snap-on cap. Qosina has more than 5,000 SKUs in its inventory, including many varieties of swabs, brushes, vials, tubing, pipettes, clamps, caps, syringes, and adapters. Custom sourcing service is available through Qosina’s specialists using the company’s extensive resources.

Qosina
Edgewood, NY
www.qosina.com

Disposable plastic module with positive seal

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Purafil, Inc. has released the 2nd Generation MediaPAK disposable plastic module. The module features the new taper fit closure (TFC), which offers a quick-connect positive mechanical seal providing a leak-free zone. In addition to the TFC, the module also features Posi-Track technology (patent-pending), an angled notch in the modules’ frame that fits onto a corresponding angled frame to create a positive seal. The TFC appears on each side of the 2nd Generation MediaPAK module. When two or more modules are adjacent within the application, the TFCs also unite to form a positive connection or seal. The TFC and the Posi-Track combine to increase efficiency and reduce air bypass and are available with Purafil’s MediaPAK PK-18 and PK-12 modules.

Purafil, Inc.
Doraville, GA
www.purafil.com

Combination steam and distillation system

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The combined pure steam and distillation unit Combitron from Christ simplifies the provision of ultra-pure media: Instead of using two units, pure steam and water for injection (WFI) can be generated in a single unit. This is made possible by the use of a first column with a larger diameter and of the natural circulation principle. The media can be produced simultaneously or separately in all columns and with an output of about 1,000 kg of pure steam and up to 4,000 L of WFI per hour. Combitron complies with the requirements laid down in cGMP and the various pharmacopoeia and is equipped with an individually programmable stored-program controller. Production data can optionally be documented in accordance with 21 CFR Part 11.

Christ Water Technology Group
Aesch, Switzerland
www.christwater.com

Solvent cartridge filters

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Millipore Corporation has announced the availability of Fortis SL cartridge filters. With broad chemical and caustic compatibility of polytetrafluoroethylene (PTFE), these filters are appropriate for use in the manufacture of active pharmaceutical ingredients (API) containing methylene chloride, acetone, isopropyl alcohol, ethyl acetate, and other organic solvents. Fortis SL cartridge filters are available in 10-, 20-, and 30-inch sizes. They can be autoclaved or steamed in place up to 135°C. The robust design delivers high bacterial retention and particle removal for bulk processing needs. The cartridge filters are manufactured with a consistent, repeatable manufacturing process that is characterized by high capacity, low extractables, and resistance to thermal and hydraulic stress.

Millipore
Billerica, MA
www.millipore.com

Germicidal UVC lamps

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American Ultraviolet Company offers a high output (800 mA), low mercury (≤8 mg) UVC lamp for improving the efficiency of indoor air-quality systems. The easily disposable “green” lamps, which are also available as standard output (425 mA) lamps, have been tested and validated to effectively perform for 17,000 hours when operated on high-frequency electronic ballasts from American Ultraviolet Company. Low-mercury UVC lamps are available for numerous germicidal products from American Ultraviolet Company, including the CC, CC-R, DC, TB, and Mobile Room Disinfection Series commercial units as well as the Sapphire™ and Eliminator RPT Series residential units. The germicidal lamps provide safe, direct exposure to 254 nm UVC radiation, which inactivates the DNA and RNA of micro-organisms, making them unable to reproduce.

American Ultraviolet Company
Lebanon, IN
www.americanultraviolet.com

Tabletop vial-filling system

Bosch Pharmaceutical USA, a Bosch Packaging Technology company, augments its vial-filling line with the FLT1020, a system designed for increased efficiency in clinical trials. The new filler is a downsized alternative to larger vial filling systems, specifically designed for the clinical/trials phase. The system offers a flexible vial processing range (diameter 16-52 mm, height 25-95 mm, neck finish 13-20 mm) and variable tray size options, with a maximum throughput of 30 VPM. The linear table-top design allows for a smaller footprint and mobility during the beginning clinical phase of drug development. It is also the only small-scale filling system that offers integrated capping and a linear “v-cleat” transport, eliminating the need for vial size parts and improving machine access while reducing overall width.

Bosch Pharmaceutical USA
Minneapolis, MN
www.boschpackaging.com

Cartridge dust collectors featuring explosion vent

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Farr Air Pollution Control is now offering its popular Gold Series® dust collector with a new high-performance explosion vent for applications involving the capture of explosive dusts. The new “X-vent” is manufactured in accordance with NFPA standards and carries CE and ATEX certifications. The multi-ribbed vent delivers a very high negative static operating pressure rating of -80 inches WC for enhanced performance, and is designed to open up at +1 psi (30 inches WC). Rated for 350°F operating temperature, the X-vent is standard on all new Gold Series collectors that require explosion protection and is also suitable for retrofit use. Made of sanitary food-grade stainless steel, it has application in the food processing, chemical, pharmaceutical, and thermal spray industries. Features include rugged 10-gauge construction for durable performance, reversible easy-to-open access doors, and a patented cambar system that allows fast, trouble-free filter change-out with no tools required.

Camfil Farr
Jonesboro, AR
www.camfilfarr.com

Long-life silicon tubing

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AdvantaPure’s APSPG silicone tubing is designed for peristaltic pumps. APSPG is made to withstand repeated compression and release for consistent, dependable performance in pharmaceutical, biomedical, biotech, chemical, laboratory, and R&D applications. It offers smooth surfaces for uniform fluid flow, resistance to bacteria build-up, and consistent pump performance. Manufactured in a certified Class 1,000 (ISO 6) HEPA-filtered cleanroom, the tubing is made from low-volatile-grade, platinum-cured silicone that meets USP Class VI and FDA 21 CFR 177.2600 standards. The tubing handles temperatures as high as 400°F (204.4°C) and is sterilizable/autoclavable.

AdvantaPure
Southampton, PA
www.advantapure.com

Vibration-canceling system

Technical Manufacturing Corporation’s Electro-Damp® PZT active inertial vibration cancelation system combines features of the company’s STACIS® active hard-mount and its Electro-Damp® active air-mount systems; piezoelectric actuators and a stiff suspension achieve efficient vibration isolation for microlithography, inspection, and metrology tools. Available in either 3 DOF or 6 DOF, the system installs easily with no feedforward required.

Technical Manufacturing Corporation
Peabody, MA
www.techmfg.com

August 25, 2007 — /FDA News/ — The U.S. Food and Drug Administration is alerting consumers that Mars Petcare US, Inc. has recalled two dry dog food products because of the potential contamination with Salmonella Schwarzengrund.

The Mars Petcare US, based in Franklin, TN, is voluntarily recalling five-pound bags of Krasdale Gravy dry dog food sold in Connecticut, Massachusetts, New Jersey, New York, and Pennsylvania, and 50-pound bags of Red Flannel Large Breed Adult Formula dry food sold in Pennsylvania. The FDA conducted tests on 10 samples, representing seven product brands from the company. Each sample (same size and brand of product) consisted of 15 subsamples, for a total of 150 subsamples. Tests of the 150 subsamples revealed two positive samples; one from the Krasdale Gravy dry food and another from Red Flannel Large Breed Adult Formula dry food.

Salmonella can potentially be transferred to people handling pet food, especially if they have not thoroughly washed their hands after having contact with the product or any surfaces exposed to the product. To date, there have been 64 cases of illness in humans related to Salmonella Schwarzengrund reported to the U.S. Centers for Disease Control and Prevention (CDC); however, none of the reported cases have been directly linked to the recalled product that was tested. The FDA is working with local and state officials, and with officials at the CDC in the investigation.

Here is identification information on the recalled products:
Product: Krasdale Gravy dry dog food
Size: Five-pound bag
UPC Code: 7513062596
Best By Date: July 16, 2008 & July 17, 2008
Best By Date Location: Back of bag
Distribution: Stores in Connecticut, Massachusetts, New Jersey, New York, and
Pennsylvania

Product: Red Flannel Large Breed Adult Formula dry dog food
Size: 50-pound bag
UPC Code: 4286900062
Best By Date: July 12, 2008
Best By Date Location: Back of bag
Distribution: Stores in Reedsland and Richlandtown, PA

Salmonella is an organism which can cause serious and sometimes fatal infections in young children, frail or elderly people, and others with weakened immune systems. Healthy persons infected with Salmonella often experience fever, diarrhea (which may be bloody), nausea, vomiting and abdominal pain. In rare circumstances, infection with Salmonella can result in the organism getting into the bloodstream and producing more severe illnesses such as arterial infections (i.e., infected aneurysms), endocarditis and arthritis.

Pets with Salmonella infections may be lethargic and have diarrhea or bloody diarrhea, fever, and vomiting. Some pets will have only decreased appetite, fever and abdominal pain. Well animals can be carriers and infect other animals or humans. If your pet has consumed the recalled product and has these symptoms, please contact your veterinarian.

Consumers with questions about the recalled product should call Mars Petcare US, Inc. at 866-298-8332.

Web site: www.fda.gov