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Archive for August, 2015

Fabs Seeking Higher Quality Electronic Materials to Meet Technology Demands

Thursday, August 27th, 2015

Manufacturers are striving to overcome limits to stay on track with Moore’s Law. Typically as the technology node gets smaller, the number of processes goes up and yield potentially goes down with each added process step.

Critical process steps in high-volume semiconductor device manufacturing at aggressive feature sizes require stringent control of variability. For a silicon wafer with 100 or more advanced logic chips, each with up to 4 billion transistors and billions of connections, it is critical to remember:

  • Essentially all the transistors and connections have to work as intended on each chip and
  • The process has to be repeatable from wafer to wafer while chip production proceeds at rates of up to 80,000 wafer starts or more per month through a fab.

A modern high-volume semiconductor fab hugely amplifies value and cannot afford any process excursions. There must be stringent focus on controlling variation in all inputs to the chip fabrication process.

Variation among transistors on a chip lead to poorer overall chip performance and must be minimized. Even trace contaminants – including those that are not specified on a standard Certificate of Analysis – can cause measurable shifts in semiconductor processes and affect chip performance in advanced devices. Given that process materials are a critical input in wafer processing, it is easy to see how the quality of electronic materials (EM) products becomes increasingly important for chip manufacturers at leading technology nodes.

Another important consideration is the challenge of the unknown: engineers don’t know how a specific impurity might impact performance. This can lead to needing additional processes and controls, which can mean higher operational costs and more risk from higher investments. Any misstep along the way – an impurity in a gas, for example—might interact in the process in unknown ways. Such a misstep can cost thousands or even millions of dollars per month.

Ensuring consistent product requires a holistic approach to quality. Instead of limiting responsibility to a quality department, it must be a priority that runs through the entire organization. As is seen in this wheel, a comprehensive quality strategy cuts across all functions that touch a product.

To meet the demands for rigorous quality control, organizations may need to hire materials scientists, chemists, and process engineers and change the culture of their organization so that every department has a strategy and plan that contributes to the overall quality vision.

Process stability across the supply chain is made possible through SPC (Statistical Process Control), SQC (Statistical Quality Control), MSA (Measurement System Analysis), and BCP (Business Continuity Planning) systems. Fingerprinting and metrology furnish the means for rigorous measurement, reducing variability, and tightening controls. Gas purity, consistency, and reliability are then delivered as an integral part of the final product.

IC technology step changes are driving electronic materials purity and analytical requirements. The bottom line? Materials suppliers must reduce variability and tighten control limits to help fabs meet market demands for more complex devices.

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This blog post was contributed by Dr. Anish Tolia, Head of Global Marketing, Linde Electronics. For more information, contact Francesca Brava at francesca.brava@linde.com.

Larger Fabs + Smaller Devices = More Gases

Thursday, August 6th, 2015

Semiconductor manufacturing fabs are faced with intense business and technical challenges to meet the demands for and costs of ever smaller and more complex devices. Semiconductor manufacturers are pushing the limits of physics and driving a constant need for new materials. The highly competitive mobile devices market is forcing fabs to ramp to higher volumes faster than ever before to meet market demands. 2014 saw a 10% upsurge worldwide in integrated circuits. Additionally, development costs for new technology can exceed $2B.

There are several factors driving the increased consumption of gases, the first being the rapid deployment of very large fabs to realize economies of scale, which are essential for profitable operation. A typical logic foundry is now running at 80,000 WSPM (wafer starts per month) and a typical memory fab is running at 120,000 WSPM. Fabs are also concentrating in clusters such as the Hsinchu Science Park in Taiwan.

In order to meet the demand and technological challenges, a larger volume and variety of gases is needed. Hundreds of gases and chemicals are used in several hundred process steps — etching/cleaning, deposition, doping, purging, and lithography/patterning — in the manufacture of semiconductors.

As process technology nodes are getting smaller, the minimal feature size at 20 nm becomes smaller than the wavelength of light and necessitates workarounds like multi-patterning to overcome physical limitations. This increases the consumption of gases per wafer.

Because of the need for low power and high performance, which 2D devices cannot handle, the industry is moving to 3D devices, which increases circuit density. This move to 3D FinFET and 3D NAND and the corresponding move to increased transistor processing — epitaxy, etch, and ALD (atomic layer deposition) — drive the need for new and increased materials to construct more complex devices.

Here are a few examples of gases that semiconductor manufacturers are using in increasing quantities.

Increased use of nitrogen

The gas most consumed in the production of electronics is nitrogen (N2). Nitrogen is used for purging vacuum pumps, in abatement systems, and as a process gas.  As process nodes are driven down and the typical fab size has increased, nitrogen consumption has grown substantially. In large advanced fabs, there can be as much as 50,000 cubic meters per hour of nitrogen consumed, which compounds the need for cost-effective, low-energy, on-site nitrogen generators.

Increased use of hydrogen

Another electronics manufacturing gas that is seeing an increase due to larger fabs and increased capacity is hydrogen. Hydrogen is used during epitaxial deposition of silicon (Si) and silicon germanium (SiGe), as well as for surface preparation. Significant volumes of hydrogen usage are also anticipated to be used in extreme ultra violet (EUV) in the future as 450mm wafers enter production streams.

Increased use of rare gases

There is also an upswing in the need for rare gases such as neon, krypton, xenon, argon, and helium. This increased usage of gases that are not as readily available as nitrogen has driven sporadic temporary worldwide shortages, particularly helium and neon. Rare gases are also used for wafer cooling (helium), as source gases in lasers (neon), and as sputtering gases (argon and krypton).

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This blog post was contributed by Dr. Anish Tolia, Head of Global Marketing, Linde Electronics. For more information, contact Francesca Brava at francesca.brava@linde.com.