2005 Top Fab: IBM

Jennifer Yario, Associate Editor -- Semiconductor International, 12/1/2005

Semiconductor International hosts an annual awards program that recognizes leading fabs in the industry today. Named the Top Fab Awards, winners are selected based on a variety of factors that include the ability to quickly introduce and ramp a product or process, a yield ramping strategy, the use of resolution enhancement techniques (RETs), and environmental health and safety excellence. This year, we are proud to announce as our winner IBM's 300 mm fab in East Fishkill, N.Y. (Fig. 1 ).

IBM Building 323 is a fully automated factory based on an advanced computer integrated manufacturing (CIM) architecture and fully automated factory control systems (Fig. 2 ). What that means is that, because of the CIM system in place, absolute reliance on human interaction is eliminated, while at the same time, the system provides an advanced platform for growth and flexibility. Development, manufacturing, engineering and terminal metals are all merged together on this platform. "We consider our fab's automation system architecture an example of a true business transformation," commented Perry Hartswick, manager of semiconductor automation and integration. "We had to take hundreds of very complex inputs, consider them in conjunction with hundreds of operational scenarios, and come up with an architecture that could run our fab in a fully automated mode. Of course, there were start-up issues, but we developed solutions to achieve outstanding operational performance, and we are building additional systems capability in a continuous improvement mode."

1. IBM Building 323 (East Fishkill, N.Y.) is a state-of-the-art 300 mm wafer fab that develops and manufactures advanced semiconductor technologies for use in IBM products and for OEMs.

IBM engineers have installed, qualified and ramped manufacturing technologies at the 180, 130 and 90 nm nodes, and are working with partners to develop other 90 and 65 nm technologies; initial work at the 45 nm node is also in progress (Fig. 3 ).

2. Computer integrated manufacturing (CIM) is a suite of applications with a full-function manufacturing execution system (MES), SiView, as the centerpiece.

"Our technologies are very advanced," said Neil Poulin, director of 300 mm special projects. "The complexity factors are incredible, with more than 50 mask levels, and many new technology innovations, so being able to control each process step is critical to our success. It only takes one process step to drift from normal to make the entire flow unacceptable for our customer set. Our process controls are world-class, and we rely heavily on them to detect signals in real time, and then automatically stop all processing from underperforming tools or process chambers."

3. IBM has demonstrated its ability to quickly ramp from a single technology at each node to multiple technologies at multiple nodes.

New technologies for lower-k dielectrics CMP methods that employ electroless techniques, and advanced metallization procedures and materials to improve diffusion resistance are currently being developed and implemented, and work has also been started on new processes for ultrathin silicon on insulator (SOI), immersion photolithography, laser annealing techniques and hybrid-orientation technology.

Manufacturing and development in the fab

Both early development and mature manufacturing of products are done at the East Fishkill facility. Inside, 75% of the space holds semiconductor equipment for 130 and 90 nm products, while the remaining 25% is used for the development of advanced technologies for 65 and 45 nm nodes (Fig. 4 ).

4. Shown here is the “main street” of IBM’s East Fishkill facility. To see the fab in action, check out IBM’s QuickTime movie at www-03.ibm.com/technology/multimedia/300mm_mov.shtml .

180 nm devices were produced and qualified as part of the startup of the wafer fab. From then on:

• The first 180 nm products performed to specification on the first fully integrated process flow to final test in the first quarter of 2003.

• In mid-2002, 130 nm technology was introduced, and in early 2003, IBM yields matched 200 mm fab die yield performance across an ASIC product set.

• In 2003 and 2004, two 90 nm technologies were introduced and qualified. By the first quarter of 2005, 90 nm production dominated the fab's wafer starts and output.

In Building 323, new processes or technologies are first established with a high-volume lead product or technology test site. Subsequent products are then installed much more quickly — the speed of ramping between products depends on the technology or type of product.

Fab productivity

Equipment productivity teams drive cycle time and tool performance improvements inside the fab. There are 12 cross-functional teams — one for each key process/equipment platform in manufacturing. A common methodology is used by each team to analyze every loss component of the process/equipment sets and develop productivity improvement plans. Because of these teams' efforts, coupled with advanced product/work-in-process management methods, Building 323 has successfully decreased cycle time x-factor by >50% to competitive levels, with an "alpha" productivity improvement of 59%. There has also been a 50% increase in fab throughput, as measured by lot moves per day.

Defect density

Overall defect levels have been vastly improved in the wafer fab since it began operations. Current defect densities are competitive and rapidly approaching leading-edge class, particularly at the 90 nm node. Methods that enabled this improvement include:

• The establishment of a continuous yield task force to drive die yield actions across multiple technology nodes.

• Benchmarking and defect information sharing with technology partners from multiple fabs building similar parts.

• Working with yield consultants to more quickly identify and eliminate primary defect sources.

• A fab-wide initiative to reduce foreign material (particles on the wafer surface).

As a result of these methods, IBM has been able to achieve a sustained defect learning rate of ~0.75× per quarter on advanced 90 nm technologies from the second half of 2004, continuing into 2005.

Yield methodology and fab yields

The IBM fab yield infrastructure has a centralized database and inline system that takes data from optical inspection tools, scribe defect macros and other in-fab data sources and correlates it to the wafer final test results. It then takes location coordinates from the optical defects found and compares them to the coordinates of wafer yield loss, which improves inline call accuracy and allows for more coordinated process actions.

The fab's yield management strategy deploys comprehensive yield learning structures in early technology phases, establishing process windows and capabilities early in the life cycle. A variety of leading-edge physical and electrical analytical techniques are also used to identify and track leading yield limiters.

To improve fab yields, there is a team in place that is responsible for reporting and tracking fab wafer yields, developing sector-specific and factory-wide scrap targets, and coordinating scrap event corrective actions. This team works with representatives from manufacturing, engineering and equipment suppliers at a toolset or process level to improve scrap levels. A compilation of all the team's action plans is incorporated into a yield improvement plan for the fab. A key methodology used to improve fab yields has been a continuous implementation of world-class process control systems, using advanced statistical techniques and fault detection methods.

Optical lithography

IBM has met the continued demands for higher resolution and larger process margins in lithography by migrating to 193 nm through a new platform chemistry, new resist design principles and the rapid tailoring of high-performance 193 nm resist systems. The fab has been able to exploit high-NA step-and-scan optical exposure tools to reduce exposure wavelength from 248 to 193 nm. Currently supported are processes with up to 50 mask levels, while processes with >50 mask levels are in development.

About a year ago, IBM ran its first immersion lithography trial, taking 300 mm wafers and printing interconnect layers with immersion in an existing 90 nm copper technology. Microprocessor chip functionality was demonstrated for the first time, and the immersion lithography results showed "in-spec" control of overlay, critical dimensions and depth of focus.

Environment, health and safety

Building 323 was originally constructed as a 200 mm manufacturing fab in the mid-1980s. IBM recycled the 200 mm fab in lieu of building an entirely new fab. "The environment was a significant consideration in all phases of Building 323's growth," said Sal Tranchina, environmental engineering manager for Building 323. "From the innovative construction techniques, to minimizing impact on water and soil, to reducing hazardous waste levels, our 300 mm fab was constructed and now operates in an eco-friendly mode. This is quite an accomplishment when you consider the myriad of chemicals and materials we use day in and day out in semiconductor manufacturing."

In addition, IBM East Fishkill and its fab have received many awards for excellence in safety performance. To be considered for these awards, a fab must work at least 2 million hours, have an OSHA rating >50% of the industry average for its SIC code, and experience no fatalities or permanent total disabilities during the covered period. Building 323 has received a fire safety "Best of Class" award — the only fab, to date, that has received this award.