Gas Handling/Delivery Systems Keep Vigorous Pace with Semiconductor Growth
As the semiconductor market continues to soar, so does the specialty and bulk gas system industry. But costs are a factor, too, as users look to shave millions in costs from billion- dollar fabs.
By Susan English
As the demand for semiconductors continues to increase–an aggregate of 16-18 percent yearly–the gas market follows in lockstep, with sales burgeoning from $100 million to $140 million–40 percent during FY94-95–say industry experts. Estimates for the 1996 gas cabinet and valve manifold box market in North America are projected at between $130 and $140 million vs. $100 million in `95; Europe at $40-$45 million vs. $35-$40 million last year; Asia at $95-$100 million vs. `95 figures of $75-$80 million; and Japan, $110-$120 million vs. $85-$95 million in `95, according to Mark McClear, marketing manager for Praxair, Inc. (Danbury, CT), a major supplier of bulk and on-site gases with nearly a dozen customer sites worldwide.
These figures are directly correlated to the big wave of capital spending on billion dollar fabs in 1994 and 1995, McClear says. Add to that a couple of newly announced fabs in Europe at the end of `95, which will probably not show up until 1997. The healthy rate of growth coincides with an ever-more cost-conscious trend in the industry as a whole, where a gas distribution system might account for somewhere between $10-$20 million, or one percent, of a billion dollar fab–a relatively small proportion. Yet, there is concern about whether that $20 million is all necessary, says BOC Gases` (Murray Hill, NJ) Marketing Manager Tom Seidler.
Gas product/service trends
Today, many high volume users buy a fully integrated package of products and services from a gas supplier. Such contracted utility suppliers are the “contracted owners” of the gas pad, and are responsible for system maintenance as well as installation. The use of centralized gas supply and distribution are mandating more centralized communications systems to link the various components throughout the fab and are also creating the demand for better methods for optimizing gas distribution.
Praxair is currently working on gas management systems in which all the components of a gas system can “talk to each other” via the Ethernet or a LAN at a remote workstation. Strides are also being made in systems design. BOC`s research scientists have developed a CAD simulation package that lets a gas system be designed and run for a period of time to determine the contamination characteristics as a function of time, says Seidler. The simulation would allow evaluation of the impact of different components, implementation of parametric studies, etc., based on a mathematical formula and sophisticated modeling, used to predict the distribution of impurities in the system. “In the past, there wasn`t the ability to actually evaluate the performance of a system until it was built, and then it was too late and nobody cared because the capital was sunk.” Now, he says, an optimum system can be designed, and therefore, an “optimum cost” to deliver predictable performance and also generate a bill of materials that will tell the user precisely what components are needed to build the system to deliver the performance.
Gas delivery systems: bulk, cylinder, on-site
A silicon precursor used in both epitaxial and CVD processes, silane is experiencing strong growth. “Silane is one of those gases that people are now asking for in tube trailers. They used to ask for it in cylinders; now they`re asking for it in trailers,” says BOC Gases` Seidler. In fact, demand for the gas is growing faster than the gas market as a whole.
Bulk silane is a new supply option also offered by Praxair. In addition to silane, the company supports the worldwide semiconductor market with a line of bulk and on-site atmospheric gases. New additions to the company`s semiconductor line include PFC recycling and recovery systems, point-of-use arsine and phosphine generation systems, and other specialty gas products.
As part of its portfolio of gas production facilities, Air Products and Chemicals, Inc. (Allentown, PA) offers a full range of high purity and ultra high purity (UHP) nitrogen plants capable of producing from 200 Nm3 and 12,000 N h3 per hour. The company currently owns and operates over 30 of these on-site nitrogen generation facilities for its electronics customers around the world. Whatman Inc.`s (Haverhill, MA) Monobed Nitrogen Generator produces nitrogen through a combination of filtration and pressure-swing absorption technologies and is capable of producing up to 850 SCFH of high purity compressed nitrogen at a dewpoint of less than -40F from any compressed air supply, regardless of quality.
The semiconductor industry has embraced the concept of automated distribution as a safe, dependable and cost effective means of specialty gas supply. Automated distribution provides the uninterrupted process gas supply crucial to keeping capital equipment continuously productive. Air Liquide`s (Walnut Creek, CA) MicroPurge Automatic Distribution System (ADS) is designed for multiplexing HPM process gases, which require continuous monitoring and automatic vacuum-assisted purging. The MicroPurge ADS is available in a variety of configurations and can provide monitoring and automatic distribution of up to eight process gas lines. Solkatronic Chemicals (Fairfield, NJ) also carries a wide range of standard manual, semi-automatic or automatic gas delivery systems for ultra-high purity gases–such as arsine, hydrogen selenide, phosphine, etc.–including cabinets, gas panels and related hardware. The company`s patented microPurge gas panel has a deep purge pigtail with a 1/4-in. tubing design for a faster, more efficient purge of the gas line than standard single-pigtail designs, according to Solkatronic.
Gas handling systems and components
The term “gas handling” encompasses cabinets, valve manifold boxes, gas panels, controllers, piping systems, isolation boxes, etc. These devices take the gases from point of storage to point of use. Cabinets and enclosures have become increasingly sophisticated and able to accommodate a formidable array of systems and equipment. But cost savings may also be realized using the “less is more” design concept. At Semicon West in July, Praxair will unveil a newly designed gas cabinet that is actually smaller in size than cabinets presently on the market. The new cabinet has a smaller cross-sectional area that will reduce the need for airflow. Another cabinet maker, Stainless Design Corp. (SDC; Mt. Marion, NY), offers hazardous gas cabinets for single-, dual- and triple-cylinder containment with removable dividers. Options include SDC`s network interface, purge gas purifier, toxic gas monitor, exhaust monitor, fire detection/suppression, plug-in pendant control panel, and shelves for small cylinders.
Another gas component manufacturer, Safety Equipment Corp. (Belmont, CA), specializes in custom-designed, welded epoxy-painted gas and source-valve cabinets and fasteners in 11-gauge steel for toxic, corrosive and flammable gases and chemicals. The company also has its own paint and plastic facility. Air Crafters Inc. (Ronkonkoma, NY) offers its HVLE and HVLR series of vertical laminar flow exhaust and recirculating hoods, which provide clean gas processing when used in conjunction with the company`s custom manifold setups. Air Crafters also features its own line of custom gas cabinets and laminar flow cabinets.
System protection is vital. The fully integrated, completely automatic low temperature shutoff and pressure-reducing systems offered by Kay & MacDonald (Orange, NJ) maintain system protection to ۫F for a wide range of gaseous services. The system is based on a patented temperature pilot coupled with the company`s Do-All regulator valve. It operates with oxygen, nitrogen, arsine and carbon dioxide and other gases and with all types of vaporizer systems. Key features are the ability to operate with lower tank pressures and with less venting of gas.
Where double-containment of gases is required, toxic gas lines are isolated in wall-mounted containment boxes. Semiconductor Equipment Technology, Inc. (SET; Pleasanton, CA) has provided a turn-key solution to the double-containment requirement: its containment boxes can be placed in the floor, allowing technicians to directly access the valves, regulators, filters and purifiers inside the box. Inert gas lines are also easier to reach, housed in a flow-through box with a perforated cover. The floor-mounted SET boxes are made standard to fit any 2-ft2 raised floor system, and can accommodate up to six gas lines and the customer`s choice of components. For retrofits of existing fabs, SET boxes can be purchased off the shelf. Adjustable internal brackets accommodate all standard regulators, valves, filters, and purifiers and removable bulkhead fittings, eliminating the need to weld components inside the box.
For use with technical gases such as steam hydrogen, gaseous oxygen, ammonia, and dry natural gas, Ultrafilter, Inc. (Norcross, GA), in conjunction with several leading chemical and gas companies, has developed a range of specialized compressed air filters. Proven efficient down to 0.01 micron, with exceptionally low pressure drops on flows ranging from 10-10,000 cfm, the filters are designed to minimize problems associated with seals and gaskets. For compressed air and gas purification, the company`s HRE (externally heated) and HRI (internally heated) Adsorption Dryer Purification (ADP) systems offer a safe solution. The HRI model is recommended for hazardous or highly contaminated locations, and is effective in situations where a lack of pure air exists or is accompanied by large flows, as well as for gases such as CO2/N2 .
For accurate and affordable measurement of the volumetric flow of air, argon, nitrogen, oxygen, hydrogen, helium, carbon dioxide, methane, propane and carbon monoxide, Matheson Gas Products (Montgomeryville, PA) features its Model LFE Series of flow meters. The self-contained Model LFE measures the pressure drop across a unique internal restriction called a Laminar Flow Element (LFE). Designed so that gas molecules are forced into moving in parallel paths along the entire length of the passage, it establishes laminar flow over the entire range of operation for a flowmeter that is inherently linear for pressure drop relative to flow rate. An instructional, five-minute video is offered free of charge by Sierra Instruments, Inc. (Monterey, CA) on its 780 Mass Flow Meter. The video describes the meter`s built-in, flow-conditioning design, allowing for improved measurement capabilities and reduced upstream piping requirements in constrained installations.
The 68920 series Digital Pressure Gauges from Cole-Parmer (Vernon Hills, IL), which have a peak hold and auto-off function, offer high accuracy [± 0.25 percent] and a digital alternative to standard analog gauges. The 68920 series is available in metric ranges, measurements in ranges up to 4,000 psig. The company`s High Accuracy Pressure Transmitters (± 0.10 percent) ensure NIST-traceable accuracy and are RFI and EMI shielded for high accuracy in industrial environments. A complete line of compact gauges and controllers is offered by Balzers (Hudson, NH), including capacitance and Piezo compact gauges for absolute pressure measurement independent of gas type. The series also includes Pirani, cold cathode and FullRange gauges. Sierra offers its Mass Flow Control, used with the Model 810 Gas-Trak, which measures and controls gas mass flow rates at a cost substantially lower than any industry-standard flow controller, according to the company, at flow rates up to 50 standard liters per minute.
This month at Semicon Europa, Setra Systems, Inc. (Acton, MA) will introduce its Ultra High Purity Series of pressure transducers and transmitters for applications involving specialty gas handling. Comprised of four pressure sensors, the 212FT, 214, 215 and 216, Setra`s ultra high purity series lets users monitor specialty gas processes on an in-line basis, as well as completely eliminate dead volume and associated problems. n
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Second-phase cleaning, final assembly, leak and performance testing and packaging take place in Solkatronic Chemicals` Class 100 cleanroom.
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A Gate OX. gas panel from Ultra Clean Technology replaces an older design
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Praxair`s GC403 UltraPurge gas cabinet features a tapered top for improved air flow and a raised, perforated floor and bottom-filtered air intake to eliminate dead pockets around cylinder bottoms.
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Air Liquide`s Automatic Distribution System (ADS) is designed for multi-plexing HPM process gases that require continuous monitoring and automatic vacuum-assisted purging.