Materials characterization crucial in Silicon Valley systems

A semiconductor manufacturer in the Silicon Valley faced a sizable setback. Something was contaminating its product, and the company halted production. That cost the manufacturer millions of dollars a day.

The company called in Fuhe Li, the Director of Advanced Materials for Air Liquide Balazs. Li’s division of the multinational, French-based company supplies material characterization services to support the semiconductor and electronics industries.

If the contamination were on the surface of the product, the cause would be in the manufacturing process. If it were in the interior layers of the product, it would point to faulty materials as the cause.

Li and his team used GD-OES, which stands for Glow Discharge Optical Emission Spectrometry. It analyses the layers of a material on the nanometer level and can reach depths of microns with a nano meter resolution. GD-OES contributes to the development of new materials with coatings at the nano-scale and upward.

Scientists also use GD-OES in many industries. That includes monitoring photovoltaic devices manufacturing, understanding the origin of corrosion on painted car bodies, assessing the composition of precious metals, controlling hard disks or LED manufacturing, improving Li batteries, detecting microchip defects and other applications.

The GD-OES analysis of the industrial contamination, using a HORIBA GD Profiler 2 revealed an impurity in the interior of the product. That meant the manufacturer had a materials supplier issue. The manufacturer’s engineers were able to identify the source of the contaminant and production resumed shortly after.

“We’re not just doing analytical work to produce results. We help them to solve their process related issues and provide solutions,” Li said. “The Profiler can provide most of the information we need and vertical location of the elements containing the contaminant.”

This was a typical situation facing the team at Air Liquide Balazs, which also works with other high tech customers like disc drive makers, the nanotech, the military and aerospace industries.

Li, who was recruited 22 years ago out of UC Berkeley where he conducted his postdoctoral studies, has a warm, hearty laugh. It belies the seriousness of his work. He problem-solves mission critical processes for technology-based companies.

Marjorie Balazs founded Li’s division in 1975. She was a pioneer in Silicon Valley at about the time when the Intel and Fairchild semiconductor businesses began ramping up their semiconductor manufacturing. Balazs saw the need for analytical material characterization.

The company has thousands of clients with the majority in the U. S. and Canada. Others are located in Asia and Europe.

Finding contaminants in the interior of the product faces challenges. Scientists use pulsed RF GD-OES to investigate materials from the surface down to more than 150 microns with a depth resolution that can be as good as 1 nm. Once the contaminant is identified, Air Liquide - Balazs scientists and manufacturers’ engineers will team up to locate the contamination source in the processes.

The production processes for these high-tech companies are secretive, involving a lot of intellectual properties. The clients do not share it with Balazs. In fact, non-disclosure agreements with the companies prevent Li from revealing the names of the company’s clients or the material contaminants found in the supplier’s materials.

The technology is a moving target.

“This industry is too dynamic, too technical, and the things that we talk about today, tomorrow, they will change the process again,” Li said. “Every day there's some new.”

Technological challenges and customer needs, Li said, are what drives this innovation.

“It's difficult to keep pace with a customer. New problems are popping up all the time. It’s because of the competition. The customers are driving all those changes.”

A substance’s elemental composition affects many of its properties.

“Material used in aerospace or that people use to build bridges, those materials can crack, peel, fatigue or rust,” he said. “It is in a very corrosive environment. So the elemental composition of the material is crucial in order to prolong the lifetime of the material.”

Li’s group uses the GD Profiler to look at the composition of the material and evaluate its content uniformity – to see whether the elements are distributed uniformly in the material. In Li’s words, he looks at the concentration variation as a function of depth. A GD-OES profile provides surfacing and uniformity information, and bulk composition.

It’s a way to make sure the supplier is sending the same product as ordered. Engineers perform incoming material characterization to make sure that they are getting the material they need.

“This is critical for several industries,” Li said. “Aerospace, they must prevent the airplane from going down because of material fatigue over time. In semiconductors, it’s to make sure parts won’t fail.”

Balazs services the consumer electronics industry, including digital multimedia communications. Every part the manufacturers use must pass rigid industrial specifications.

GD-OES isn’t the only method used to inspect materials. Many older, more expensive and slower techniques have been more widely accepted in industry because they have been around longer.

“There are no techniques can do it all,” Li said. “It really depends on what problem they have. We are the experts that decide what technique to use.”

Li is a proponent of glow discharge technology.

“The information that we provide to customers is very valuable,” he said. “Some of the information we provide to our customers with a GD-OES is something that our customers have never had in the past.”

For example, Li’s group used GD-OES on insulating materials, and were able to profile it from its surface down to 50 to 60 micron in depth. No other technique, especially those traditional electron beam and ion bean technologies could accomplish that, Li said.

“The beam has charge,” he said. “When you shoot the charged beam onto insulating materials, you will create a charging effect that usually prevents us from getting any reliable information from the material. That charging effect is very bad and very severe. Sometimes it doesn’t generate any signal.”

GD-OES doesn't have that effect. Li uses an RF alternating current, sputtering material layer by layer. He wrote a couple of papers on that, trying to promote GD-OES as a viable technology.

 “We can change the industry techniques that are common practice by using a HORIBA non-traditional approach to improve industrial common practice.”

Li said the stress and challenges brought by constant crisis is worthwhile.

“At the end of the day when I drive home, I just feel they're rewarding. You're helping customers, you're making direct impact on a society, and we're making a difference.”

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