By Pete Singer, Editor-in-Chief
In a push to meet the chip supply crunch, fab utilization is at record high of 97%+. In addition, corporate social responsibility (CSR) and sustainability priorities are growing and chip makers are seeking more initiatives to reduce environmental impact.
“This is a challenge across all manufacturing facilities but especially for mature fabs who need to increase production without access to the latest machinery,” said Troy Metcalf, President of Edwards Semiconductor Service.
Maintaining that record high level of utilization isn’t easy. Manufacturers are constantly looking for ways to minimize both planned and unplanned downtime.
The most obvious target for this is the large processing equipment, but increasingly the equipment in the sub-fab – where vacuum pumps, gas abatement, filtration, piping and other support equipment resides – is under scrutiny. The good news is that suppliers such as Edwards have proactively been working on ways to improve not only their own equipment but boost overall fab efficiency and productivity.
“A recurring question is how can vacuum and abatement systems in the sub-fab and cleanroom be a driver of fab success?,” said Metcalf.
The answer: “We have many customers that we have helped get ‘a new lease of life’ in their maturing fab facilities,” said Metcalf. “Based on the data we have collected and our experience gathered over a lifetime of supporting, repairing, and refurbishing these types of
systems and equipment, we are in prime position to understand the maintenance requirements of these more mature facilities and recommend the best solutions to improve their targets,” he said.
“Smart Manufacturing” in the sub-fab means connecting information about operational per- formance to creative humans in order to deliver the best results for fab success, he adds. Part of this is using predictive data models and best-known methods to help optimize sub-fab service intervals to positively impact fab metrics. “That might be using our knowledge to improve equipment performance to extend meantime between service, or simply making recommendations to perform vacuum system maintenance aligned with tool maintenance,” Metcalf said.
In one specific case study, a foundry realized that all areas of the manufacturing chain needed to increase their contribution to fab yield. Their vacuum and abatement systems had evolved over the years, concealing hidden variables affecting the potential performance of the wider fab. Unplanned vacuum system failures during wafer processing were a pressing concern. Advancing semiconductor manufacturing processes were also placing increasing demands on vacuum and abatement equipment.
The fear was that a pump “crash” during a batch process that causes the scrap of an entire production batch –up to 125 wafers could be a huge loss in product and process downtime. Even in the single wafer processes, unplanned vacuum pump faults could cause significant losses as process tools require many hours or even days to requalify.
The solution: Fab and sub-fab teams started to move their thinking from the traditional “break-fix” approach to how to optimize and align their service schedule to better support the process tools. This formed an approach of Operational Excellence, where the operation of people, machines, processes and data all worked together to achieve the best results. Predictive Maintenance (PdM) and Remaining Useful Life (RUL) technologies were installed in parallel with the existing sub-fab monitoring system. Leveraging their domain expertise to understand vacuum pump condition, operational excellence specialists at Edwards created a condition-based mainte- nance plan which centered around the objectives of the wider fab.
The outcome: By extending their fault prediction horizon, the sub-fab team was able to notify the process tool owners 6 weeks in advance of sub-fab maintenance requirements (see Figure). With the confidence provided by verified RUL calculations, the fab team agreed to extend maintenance intervals by at least 6 weeks (25%), without any risk of unplanned downtime. The overall effect was to reduce the risk of wafer losses, and performance improve- ments continue to be visible across the entire fab, as tool availability and fab yield improve.
Noting the Edwards strategy of “Operational Excellence,” Metcalf said it’s important to get a complete view of the impact vacuum and abatement has on the key per- formance metrics. This is largely done through SQDCPE — Safety, Quality, Delivery, Cost, People and Environment — used to measure and track performance
• Safety – The sub-fab is a dangerous environment. Harmful materials and people interact closely with machines. It is important to review key performance indicators (KPIs) and how they impact both the Fab and the sub-fab.
• Quality – As the number of processing steps required by leading edge processes has grown, so has the impact of vacuum and abatement on line and even die yield. What may seem like minor improvements to yield can have a huge impact on KPIs.
• Delivery – Thousands of hours of process tool time is still being lost each year, due to unplanned maintenance. If an unexpected event in the sub-fab causes a tool or chamber to be down, wafers can be lost or delayed when waiting for the tool and the cycle time for those wafers will increase.
Cost – The impact on wafer cost can be direct or indirect. The indirect costs, including the opportunity cost of lost production on process tools far outweighs direct costs, especially if the down tool is a bottleneck tool.
• People – Creating integrated circuits requires many people with a wide range of skills and both theoretical and hands-on knowledge. These skills range across physics and chemistry, materials science, electrical engineering and electronics, mechanical engineering, control systems and more.
• Environment – Many measures are needed to achieve sustainability objectives – energy efficiency programs, strategic renewable energy initiatives, reduction of greenhouse gas emissions and established climate change countermeasures.
“We work in partnership with cus- tomers to maximize tool availability and get more from their supply chain, all at the lowest environmental cost,” Metcalf said. “We work with customers to grow fab value and deliver outcomes in the form of reduced risk and uncertainty.”
Metcalf said that in order to better work in partnership with North American customers and mitigate the effects of supply chain shortages, Edwards recently invested in a new manufacturing facility in Chandler, AZ. “With this new facility we will align our service support directly to our customer goals, while reducing the carbon footprint of their supply chain,” he said.
The new 200,000-square-foot facility will leverage the latest manufacturing and digital technologies to support the fast-growing North American semiconductor market with services and solutions for the efficient and environmentally sustainable production of chips. The Chandler facility will also feature warehousing facilities, factory areas, meeting rooms, and a dedicated training center.