Microcontamination, despite high yield, can cause long-term reliability issues

By Lynnette Reese, Editor-in-Chief, Embedded Intel® Solutions

According to SEMI (semi.org), the global semiconductor revenue forecast for the second half of 2018 was doubled from 7.5 to 15 percent, a substantial growth. The semiconductor industry has seen cycles of growth and stagnation before, as innovative new products peak and decline before new technologies come out to drive growth from another direction. The wide adoption of personal computers marked great growth in semiconductors; a market that has been dominated by Intel for decades. When the PC market began to mature, a period of stagnation was followed by the mobile computing era. Companies like Qualcomm and MediaTek emerged as key players in the mobile industry. However, both computer and mobile sectors are now sustainable, but not growing appreciably.

Recently, multiple growth engines have kicked in for semiconductors, driving a new era of growth. Growth drivers include data centers, a growing “economy of data,” artificial intelligence, virtual reality, autonomous vehicles, and increasing automation in industrial applications, particularly in the Internet of Things (IoT) and robotics. The concurrent emergence of several new markets and applications has prompted a high demand; from leading edge chips on down to some of the legacy nodes. In turn, growth in semiconductors is driving the need for materials and better technologies for Integrated Chips (ICs).

Companies feeding the boom with materials and chemicals for making ICs are seeing growth that shows no signs of abating. One materials company, Entegris (ENTG), has recently expanded its Kulim manufacturing capacity and capabilities, adding new tooling, molding machines, and numerous updates to the assembly area so that Entegris can meet the demand for wafer handling products. Entegris is a 52-year-old company that, for context, was founded two years before Intel Corporation. Entegris provides materials and material solutions to semiconductor companies (semis). Currently, the company has about 4,000 employees with sales revenue of approximately $1.5 billion. Entegris has been expanding rapidly in recent years, achieving growth by about two to three percent above the market. The company is now viewed by most investors as a growth company than as an industrial, “cyclical business” type of company. Entegris is assisting the semiconductor industry in two ways: by helping the semis realize more advanced technologies and by providing materials for making chips.

Entegris has three divisions that address three different elements of semiconductor manufacturing. The first division provides advanced materials such as specialty chemicals, specialty gas mixtures, cleaning chemicals, deposition chemicals, specialty coatings, graphite, silicon carbide (SiC), and many other materials that fabrication plants (fabs) use to make chips. The second group at Entegris is involved in benefiting materials handling with carriers for handling wafers and photomasks, wafer and reticle handling, fluid management, sensing, control, and supply and delivery of chemicals to fabs. It is chip growth that primarily drives the growth of all Entegris’ divisions, with some growth influenced by advances in technology. The third division focuses on microcontamination control and primarily handles leading edge filtration and purification (at levels measured in parts per trillion). Microcontamination control is presently the fastest growing division at Entegris. Anything that touches the semiconductor wafer must go through a filter and purifier, whether gas, liquid, photo-resist, slurries, or other chemicals.

Why is microcontamination control important?

Technologies continue to improve such that the industry is now producing Systems-on-chip (SoCs) at the 7 nm node and is headed to 5 nm. At such a scale, any particle or contaminants can make a chip fail. Enterprises like Entegris’ microcontamination control group are the last line of defense against contaminants for all chipmakers. Entegris works with automakers and mainstream fabs to investigate reducing some of the contaminants and particles that are not affecting yield yet are causing critical problems in long-term chip reliability.

According to Wenge Yang, Vice President of Marketing Strategy at Entegris, “Many existing and mainstream fabs are yielding high 90 percent range. However, we recently found that particles that are small enough to not cause a reduction in chip yield – can still cause reliability issues down the road. This has triggered Entegris to become an industry advocate on a new effort to reduce contaminants even further than has been practiced up to now.”

A Hot Topic

Entegris spotted a trend emerging about a year or two ago as semis began rooting out causes affecting long-term chip reliability that included microcontamination that did not affect yield but could affect a chips’ long-term reliability. There’s no greater concern for reliability than in autonomous cars; it’s become a hot topic.

The Society of Automotive Engineers (SAE) International issued a standard (J3016) that defines six levels of automation for self-driving cars. Level zero has no automation whatsoever. Adaptive cruise control is a Level one feature. Level two specifies partial automation. Level three defines conditional automation, such as Tesla’s Autopilot. Level four demonstrates a high level of automation where the car can operate without human oversight under certain conditions. Level five is full automation with no human involvement.

“One of the most interesting things we have seen is that with the growth of some specific sectors, the design and manufacturing challenge is changing,” Wenge affirms. “One example is in the automotive industry. If an automobile used only two or 300 chips total, the failure rate is not causing that much of a headache as it does if you have 10,000 chips in one car.”

Level Five autonomous cars may have as many as 10 LiDAR systems around the car, gathering data and processing signals and images in real-time, with low latencies. A fully autonomous car might have 10,000 ICs with 50 percent of the cost of the car sunk into the electronics. With that many chips in one autonomous vehicle, automakers begin to parallel NASA-level care in design and manufacturing, but without the added safety of redundant systems due to cost and size constraints. Add to this pressurized scenario the harsh automotive environment with extreme temperatures and constant, heavy vibration.

“With these many chips in each car, if you have a failure rate of one chip out of one million, then several hundred cars might fail on the roads every single day,” states Wenge. The resulting repairs, medical bills, and lawsuits would be costlier than fixing the reliability issue at the outset. “For Entegris, the intrinsic need for increased reliability is an excellent opportunity.”

The military, aerospace, and avionics industries commonly employ redundant systems. However, the automotive industry cannot afford redundant systems, which means that we must improve the single systems’ reliability. The Level Five autonomous car sends processed data feeds into a central computer that decides whether the car should brake, slow down, accelerate, and so forth. If any component in any autonomous automotive systems fails, the car may not collect crucial data.  If the car has made a decision, it may be unable to execute on it. The possibility for failure is multiplied as automakers load thousands of ICs in a single car.

As Wenge points out, “Autonomous car makers start to realize, ‘If I put that many chips into the car, I run the risk of reliability everywhere.’ Of greater concern are chips that have passed on down the line as ‘good’ in a 100 percent yield batch…but can still fail in the field. This is how the topic of detailed reliability gets triggered.”  The design process for automotive applications must be accompanied by very high awareness of the reliability consequences. States Wenge, “Entegris is providing solutions to eliminate some of the random inferences impacting reliability.

Wenge Yang, Ph.D. Vice President, Market Strategy Dr. Yang joined Entegris in 2012 to serve as the Vice President of Market Strategy. In his role, he is responsible for Entegris product and market strategy, market research and market trend analysis, strategic marketing, and the company’s strategic technology roadmap. Before joining Entegris, Dr. Yang was an equity research analyst at Citigroup covering the semiconductor equipment and materials sector. He also served in various executive roles at Advanced Micro Devices, Tokyo Electron, and two start-up companies. Dr. Yang received a Ph.D. in Materials Science and Engineering and an MBA from Rensselaer Polytechnic Institute. Master of Science degree in Mechanical Engineering from the New Jersey Institute of Technology, and a Bachelor of Science degree in Materials Science and Engineering from Shanghai Jiao Tong University.