Category Archives: Materials and Equipment

By Peter Salmon, Salmon Technologies

A particularly versatile form of wafer bumping is stud bumping, using either gold or copper wire. The equipment required is an adaptation of a traditional wire bonder. A ball bond is made at a first contact pad using heat and ultrasonic energy. The wire is extended in a precise direction and a flying lead is created by terminating the wire, for example using electronic flame-off (EFO). This type of stud bump can be used as a buckled pillar connector, enabling electronic assemblies that are put together with screws rather than solder. With appropriate assembly and testing techniques, this can lead to waste-free integrated assemblies; no good parts are thrown away due to compound yield problems, otherwise known as Known good die (KGD) problems.

Manufacturing Sequence for Buckled Pillar Connectors
The animation depicts the manufacturing sequence for a particular case involving a top and a bottom substrate with two layers of ICs in between. The preferred substrates are copper for reasons relating to power dissipation and water channel construction. A copper substrate is shown with interconnection circuits fabricated on top. The interconnection circuits are fabricated on large copper panels using direct laser imaging. The starting point includes a bottom layer of ICs already mounted using buckled pillar connectors and wax, using the method described herein.



figure 1:Manufacturing sequence for buckled pillar connectors.

First, ball bonds, the beginnings of buckled pillars, are placed at 4 locations. Flying leads are created by moving the bonding tool away from the ball bonds, in a direction slightly away from normal, to create a predictable flexure direction for the buckled pillar. Next, electronic flame-off is used to terminate each wire in a spherical ball. An alternative method is to use a spark discharge.

A top-layer IC chip is then flipped and placed on top of the lower IC chip, and similarly constructed wires have are formed. The wire diameters may vary roughly in accordance with their length. The bonding tool is programmed so that all the spherical balls have approximately the same height. Melted wax is applied so as to cover all of the spherical balls, and then hardened. Chemical mechanical planarization (CMP) provides a uniform height for all of the wires; typically the spherical balls are removed in this step. Finally the top substrate is inverted and aligned; contacts are established between the tips of the pillars and corresponding capture points; and the structure is compressed a precise amount using assembly screws (not shown in the figure). The wax is heated to soften it during this assembly process. The buckled pillars so produced are shortened by a few percent in length. They maintain their elastic property and act like springs. The spring action helps to make good contact, and provides some design margin against deviations from co-planarity of the wire tips.

Conclusion
The described method for making buckled pillar connectors draws on mature techniques for making stud bumps, and for planarization using a wax filler. The resulting electronic assembly is solder-free, thus avoiding many of the reliability issues that accompany the use of solder. The technique is versatile and can be adapted to many different substrates and chip stack configurations. As shown in the animation, no through silicon vias (TSVs) are required. By combining these methods with water cooling channels provided between selected ones of the copper substrates, an effective system integration method becomes available, without depending on chip modifications.

Peter C. Salmon, VP can be contacted at Salmon Technologies, LLC, 200 E. Dana St. #8
Mountain View, CA 94041; 650/814-1076; email: [email protected]

Sept. 10, 2008 – The semiconductor equipment sector has been sputtering along at three- and five-year lows in terms of demand. And in case you’ve missed it, SEMI has new data to remind us.

Tracking global data with the Semiconductor Equipment Industry of Japan, SEMI says revenues for chip equipment totaled $7.83B in 2Q08, declines of -26% from 1Q08 and -29% vs. 2Q07. Orders were down -13% Q-Q to $6.99B, representing a -30% decline from a year ago. And unlike previous quarters, the numbers are ugly across the board.

Back in 1Q08 some regions seemed to be working through the downturn fairly well: China (25%) and Taiwan (18%), with Japan (5%) and even North America (3%) were well ahead of tool spending from the prior year.

But in 2Q the picture looks a lot bleaker: Every region except rest-of-world shows double-digit losses in both sales and orders. China swung from first to worst (-42%) in Q-Q sales of semiconductor tools; Taiwan spending slumped -39%, North America -32%. Compared with a year ago, both China (-61%) and Taiwan (-55%) have slashed spending by more than half, with Korea down -20%.

Another way to illustrate the industry’s swerve into the ditch: equipment billings in 1Q had actually improved 7% Q-Q, and were down just -2% Y-Y. Just one quarter later those numbers had sunk to -26% and -29%.

But there may yet be a ray of hope in all the carnage. Notice that bookings in 2Q08 actually improved Y-Y, to -13% vs. -23% in 1Q08. Customers first place their tool orders and then months (or quarters, or longer) the equipment providers record the sales, so any recovery logically will be first seen in the bookings side of the equation. Indeed, SEMI and others have said that spending should pick up again in 2009 — but for now, the questions are how low will demand go, and when in 2009 will we see a real sustainable comeback.

September 4, 2008: Pioneer Surgical Technology has received 510(k) clearance from the US Food and Drug Administration (FDA) to market FortrOss, a novel bone graft substitute utilizing the power of nanotechnology for orthopaedic applications. The FortrOss bone void filler is a scaffold for the in-growth of new bone and other connective tissues, when superior bone regeneration is required.

“The FortrOss carrier is a collagen-based bioscaffold processed to provide an osteopromotive effect,” with a patented “E-Matrix “technology that provides an open structure for bone growth and repair, explained Ron Hill, VP of research and development at Pioneer. The osteoconductive matrix in FortrOss utilizes Pioneer’s nanOss technology and is designed to mimic the nanostructures inherent in boney tissue.

Pioneer’s president and CEO, Matthew Songer, stated that the Fortr0ss bone graft substitute is the result of work leveraging a pair of 2007 acquisitions: Angstrom Medica’s nan0ss material, and the osteopromotive scaffold technology of Encelle Inc.’s E-Matrix biopolymer, “to create the most advanced bone void filler on the market.”

Edward Ahn, VP of biomaterials at Pioneer, added that the nanOss hydroxyapatite in FortrOss “resembles the size, shape, and chemistry of native bone,” so that boney tissue “recognizes it as native tissue.” This “mimicry of native bone makes nanOss superior to other calcium phosphates on the market.”

FortrOss is expected to be US market released later this year.

September 3, 2008: FEI Co., a provider of atomic-scale imaging and analysis systems, has released its new extreme field emission gun (X-FEG) electron source module for the Titan family of scanning transmission electron microscopes (S/TEMs).

The new technology combines higher brightness — previously available only with more complex cold field emission — with the high, ultra-stable current of thermally-assisted field emission. This combination provides improvements in resolution, speed, sensitivity and ease of use to the Titan.

“The X-FEG’s combination of high-brightness and high-stability beam current provides benefits to users at all levels over the full spectrum of TEM applications,” said Rob Fastenau, FEI’s EVP of marketing and technology, in a statement. “It increases throughput, improves resolution without adding complexity to the optical system, and eliminates cleaning and maintenance procedures required by cold field emitters. For those using spherical aberration correctors and/or monochromators, it provides additional gains in resolution, precision and sensitivity. In the most advanced uses, the X-FEG can be combined with sophisticated experimental technologies, such as chromatic or spherical aberration correctors or low accelerating voltages, to explore the ultimate limits of S/TEM performance.”

The X-FEG can be fitted to any Titan TEM and provides benefits above and beyond those of correctors and monochromators already installed. Initial shipments of the new source are planned for the first quarter of 2009.

HR-TEM image of a partially filled single-wall carbon nanotube at 80kV acceleration voltage using a monochromator gun with X-FEG on a Titan with image Cs corrector (1 s). The high brightness of the X-FEG allows for atomic resolution imaging at 80kV with short exposure times. (Source: FEI, courtesy of Prof. N. Kiselev, Institute of Crystallography, Moscow, Russia)

September 2, 2008: Bruker AXS GmbH has completed the acquisition of Surface Imaging Systems GmbH (SIS), a developer of advanced atomic force/scanning probe microscopy (AFM/SPM) systems. SIS will be renamed Bruker Nano GmbH and will operate under its previous management.

SIS’ systems are used for numerous applications in materials research, including semiconductors, data storage, electronic materials, solar cells, polymers and catalysts. The core technology consists of extremely compact AFM/SPM components that can be used easily with many instruments, such as optical microscopes or micro-hardness testers, explained Frank Burgaezy, EVP of analysis tools developer Bruker AXS, in a statement.

“The most widely distributed SIS product is the ULTRAObjective, a compact AFM add-on unit which can be easily integrated with standard optical microscopes,” added SIS managing director Frank Saurenbach. “This straightforward integration provides direct access to the nanoworld, without compromise.”

The ULTRAObjective, the central part of all Bruker AFM stages, is a small and versatile AFM/SPM scanning head for integration into the turret of research microscopes and various OEM applications. (Photo: Business Wire)

ESD prevention and protection


September 1, 2008

Compiled by Carrie Meadows

No matter where you sit, stand, or walk, or what you wear in a critical, clean environment, eliminating electrostatic discharge is a top consideration. To eliminate shocking results, here’s a sampling of ESD prevention and protection products.

Static control blow-off gun

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The durable 190 HP (90803-11080) ionization gun is designed for applications with a large coverage area or drying and cooling requirements such as for circuit board applications. The 10 to 1 boost from the venturi also makes the 190 HP a very energy and compressed air efficient static control blow-off gun. The 190 Series guns can be factory rebuilt and guns and power supplies can be replaced separately, resulting in a very low lifetime cost of ownership. The Standard Model T series AC power supply (sold separately) is available in 120-V or 220-V primary and 4-kV output and can support two guns. The Model B series Equal-Ion power unit (sold separately) is designed to be used with the 190 Series static control guns in applications where

The nano revolution


September 1, 2008
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The number of products incorporating nanoscale materials is increasing at a rapid rate, but manufacturers are still struggling to find ways to control these materials in the production environment as they ramp up to commercial scale.

By Sarah Fister Gale

In the past few years, the nanotech revolution has gone from great ideas to commercial realization. Manufacturers across multiple industries, from pharmaceuticals and health care to coatings, semiconductors, and microelectronics, are recognizing the current and future impact nanomaterials can have on their products.

Nanomaterials offer great promise for a new generation of products because they deliver higher strength, lower weights, and more easily soluble attributes than have been previously seen in conventional materials.

“Nanotech isn’t a new market or industry–it’s an enabling technology that improves many types of products,” notes Jurron Bradley, senior analyst at Lux Research, a provider of strategic advice and intelligence for emerging technologies, based in New York. “You find it in coatings boosting the efficiency of automobile engines, in nano-enabled finishes protecting electronic devices, and nanoparticulate reformulations that make cholesterol-reducing drugs more effective. These innovations aren’t always visible to consumers, but they improve products and boost margins. That’s why nanomaterials use is only going to keep growing.”

The market has seen recent rapid growth, with great expectations for the near future, says Bradley. In its recently released report, “Nanomaterials State of the Market Q3 2008: Stealth Success, Broad Impact,” Lux estimates that nanotechnology was incorporated into $1.4 trillion worth of products in 2007, up from $497 billion in 2004, representing a compound annual growth rate of 41%. The research firm expects this figure to grow at a compound annual growth rate of 14% through 2015, climbing to $4.0 trillion worth of manufactured goods in that year.

The report notes that established nanotechnology–which includes nanoscale objects and devices based on long-known processes and technologies, such as semiconductor chips with nanometer features and nanoscale particles such as carbon black–dominates the current market, accounting for $1.3 trillion of the $1.4 trillion in nano-enabled manufacturing output in 2007. By 2015, Lux expects emerging nanotech–novel materials currently under development–to take center stage, accounting for $3.1 trillion of the $4.0 trillion in output.

The materials and manufacturing sector saw the greatest impact as nanotech made its way into intermediates like coatings and composites for products like automobiles and buildings; electronics followed at $35 billion from emerging nanotech applications in fields like displays and batteries, while health care trailed with $15 billion in revenue, driven by pharmaceutical applications.

“We are seeing a lot of growth in the electronics and IT sectors,” Bradley says. “Manufacturers still have to prove the technology is viable, but they are seeing much greater acceptance.”


Figure 1. An atomic force microscope (AFM) image of Unidym carbon nanotubes (CNTs) on a substrate. Photo courtesy of Unidym Inc.
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That acceptance is coming after years of trial and error among researchers on how to scale up from the lab to a volume manufacturing facility. From managing human health and safety issues and designing air handling and filtration systems that can manage nanoscale particles, to controlling the way materials are introduced into the environment, processed, and removed, manufacturers are being forced to re-evaluate all of their contamination control processes for the nanoscale.

But is it safe?

A flurry of attention-grabbing research reports and studies warning of the dangers of nanomaterials from special interests groups, such as the Project on Emerging Nanotechnologies and Friends of the Earth, have gained much media attention over the past couple of years, inciting fears among consumers about risky nanomaterials in their products and demanding caution from manufacturers unsure about whether to risk using a product that has potentially or perceived harmful consequences. Even as these materials are proved safe, public perception of risks can have lingering negative effects on marketability, particularly for products sold directly to consumers.

“There is still a lot of concern about nanoparticles,” notes Harry Way, technical director of Netzsch Fine Particle Technologies, a manufacturer of advanced process technology for nanomaterials based in Exton, PA. “In reality, though, we’ve all been exposed to nanoparticles for as long as we’ve been burning things.”

In spite of that statement, the use of nanomaterials in products and the accompanying concerns have made environmental and human health and safety a top priority for standards writers and special interest groups.

A report released in July 2008, “Nanotechnology Oversight: An Agenda for the New Administration,” by former Environmental Protection Agency (EPA) official J. Clarence Davies calls for greater oversight in the use of nanotech materials and defines a roadmap for the next presidential administration that includes immediate and longer-term steps to shore up what he sees as shortcomings of nanotechnology oversight.

Davies calls for the White House and federal agency policymakers to maximize the use of existing laws to improve nanotechnology oversight by defining nanomaterials as “new” substances under federal toxics and food laws, thereby enabling EPA and the Food and Drug Administration (FDA) to consider the novel qualities and effects of nanomaterials. Davies also calls for federal pesticide and workplace safety laws to be used to protect against potential adverse impacts of nanomaterials.

The report highlights the importance of creating sensible nanotechnology policies that will help ensure the safe and sustainable application of nanotechnologies to climate change, food security, water purification, health care, and other pressing global problems.

“The next presidential administration will face a host of complex policy issues concerning energy, the environment, food safety, consumer products, and the workplace,” he writes in the report. “One issue, however, that will impact virtually all of these policy areas is nanotechnology oversight.”

The National Institute for Occupational Safety and Health (NIOSH), the leading federal agency conducting research and providing guidance on the occupational safety and health implications and applications of nanotechnology, is conducting ongoing research into 10 areas of concern that it has identified for safety research regarding the use of nanomaterials. These include toxicity and dosages, fire safety, effectiveness of engineering controls, and safety of current exposure levels.

Meanwhile, many other global organizations are producing their own research and standards documents relating to nanotechnology, including the American National Standards Institute (ANSI), the Institute for Electrical and Electronics Engineers (IEEE), The British Standards Institute (BSI), and the International Organization for Standardization (ISO).

The first steps have been to create standards for measurement, nomenclature, and characterization of nanomaterials, notes Kalman Migler, in the Materials Science and Engineering Laboratory at the
National Institute of Standards and Technology (NIST), a non-regulatory federal agency that advances measurement science, standards, and technology, based in Gaithersburg, MD.

“We need to develop reference materials so that we all have the same samples to do the same tests,” he says of the need for standards concerning these issues. “Standards for nano will create immense value by bringing order and efficiency to the marketplace.”

Migler points out that in order to accurately assess the toxicology or characteristics of nanomaterials, the fundamental properties must first be agreed upon. “It creates a uniform approach and develops confidence between buyers and sellers.”

A group within IEEE, a non-profit professional association for the advancement of technology based in Piscataway, NJ, produced IEEE 1650

August 28, 2008: CytoViva Inc., a provider of optical imaging solutions to the nanotechnology research market, has integrated new hyperspectral imaging technology (HSI) with its advanced nanoscale microscope system. This combination of technologies will enable scientists to make advances in a wide range of nano-medicine and nano-materials research initiatives.

Hyperspectral Imaging is a method for identifying the presence of materials and biologicals based on their unique “spectral signature.” By incorporating HSI with CytoViva’s nanoscale microscope system, scientists can quantitatively confirm the presence of specific nano-scale materials, with HSI capturing and reporting this spectral data within each individual pixel of an image.

A primary application for this technology includes research of nanoparticles used as a targeted drug delivery vehicle for treating cancer. With the CytoViva system, scientists can observe these nanoparticles as they are absorbed by the cancer cells and quantitatively confirm this process through identification of the particle’s unique spectral signature.

“The development of our hyperspectral imaging capability was driven by customer requirements to quantify images from their CytoViva microscope system,” according to CytoViva president Chuck Ludwig. “Now these scientists will be able to create spectral signatures of nanoscale materials as they interact with biological or polymeric composites. In addition HSI can often quantify the presence of materials not easily observed, even when using our advanced optical microscope system.”

August 26, 2008: IBM says it has integrated and controlled an electrically driven light emitter based on a single carbon nanotube, which it says is a first step in developing nanotube-based integrated electronic and nanophotonic devices. The research is described in the Aug. 25 issue of the journal Nature Nanotechnology.

Semiconducting single-walled carbon nanotubes have a direct, diameter-dependent bandgap and can be exited readily by current injection, making them attractive as nano-emitters with spectrally broad and spatially nondirectional electroluminescence and low radiative yield, note the researchers from IBM’s TJ Watson Research Center in Yorktown Heights, NY.

Their work involves combining a single nanotube-based field-effect transistor (FET) with a pair of metallic nanomirrors on a chip. They were then able to control the optical emission properties from the 2nm-dia. nanotube including emission wavelength, spectral and spatial distribution of emitted light, and efficiency of emission, displaying “an unprecedented level of control over electrically-driven light nano-emitters.” The spectral full-width at half-maximum of the emission was reduced from ~300nm to ~40nm at a cavity resonance of 1.75μm, and the emission becomes highly directional, they report. The maximum enhancement of the radiative rate was estimated to be 4, and both the optically and electrically excited luminescence of single-walled nanotubes involved the same E11 excitonic transition.

The work demonstrates the concept of a “cavity-controlled” light source, where emission from optically active materials is controlled using an optical cavity, where light is bounced back and forth and interacts with active materials. A laser is one example of such a structure; now, nano-cavities are shown to control and improve properties of individual, single-walled carbon nanotubes, indicating they might be used in integrated nanophotonic circuits, quantum optics, and high-performance on-chip optical interconnects and sensors.

Building an optical cavity around the light-emitting nanotube mirrors (see bottom and top), IBM scientists were able to confine wavelengths to the desired 1.55μm communications frequency. (Source: IBM)

by Debra Vogler, senior technical editor, Solid State Technology

August 21, 2008 – This week Dow Corning unveiled a new thermally conductive compound, called “TC-5688,” at the Intel Developer Forum (8/19-8/21, San Francisco, CA), touting it for use with Intel’s newest mobile microprocessor, the Intel Core2 Extreme mobile processor QX9300.

The significance of the new non-curing thermal interface material (TIM) is its resistance to “pump out” — i.e., thermal resistance does not increase under power cycling — that has been seen with materials in the past. This makes it suitable for multi-chip packaging applications (see figure below). The company says the material exhibits “extremely low thermal resistance” at 0.05°C-cm2/W and high thermal conductivity at 5.67 W/mK

Andrew Lovell, industry marketing specialist at Dow Corning, explained to SST that during power cycling, microprocessor die can flex due to coefficient of thermal expansion (CTE) mismatch, placing thermo-mechanical stress on a TIM. “Multi-chip packages may enhance these stresses due to potential die height offset and other factors,” he said. Dow Corning benchmarked its TC-5688 against two competing materials on a multi-chip tester that simulates a mobile processor. The power cycling consisted of the device being on for six minutes and then off for six minutes; the junction temperature reached ~85°C during the testing. The cycle was repeated ~2000 times.

“While the thermal grease and phase change material exhibit rapid and significant degradation of their thermal properties, TC-5688 shows almost no sign of change in performance,” said Lovell. In particular, the phase-change material that was tested showed breakdown after ~500 power cycles. — D.V.

Power cycling data on a multi-chip tester. (Source: Dow Corning)
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