Bringing a new fab on-line: How TSMC Fab 6 got up and running
08/01/2001
Nun-Sian Tsai, TSMC, Hsinchu, Taiwan
In today's economy, only the largest semiconductor companies can profitably operate their own fabs. As a result, smaller "fabless" firms rely on foundries to manufacture their products, and many larger companies are also moving to a business model in which entire product lines are strategically outsourced to foundry companies.
These conditions have created a large and vital foundry industry, in which manufacturers must continually expand their process technologies, capacity, and services to meet increasing demand. Strategies for building new facilities have become especially important to players in this market, since advanced process development requires tremendous resources and skills. From this perspective, it makes sense for companies to plan not just for one fab, but for an entire series of manufacturing facilities to be built over a long period of time. Taiwan Semiconductor Manufacturing Co. (TSMC)'s Fab 6, located in the southern Taiwan city of Tainan, provides a good example of this building strategy.
 Figure 1. Diagram showing Fab 6 surrounded by future fab sites, including Fab 14. |
Fab 6, which is now delivering 200mm wafers in volume production and fully functional 300mm customer chips, includes the largest manufacturing ballroom in the world (190,000 ft2), with offices and facilities spread over six floors. It features TSMC's last 200mm manufacturing line, a copper interconnect manufacturing capability, and the first 300mm foundry line to produce customer wafers. In addition, because the plant is located on a green field site, TSMC has broad flexibility to cluster up to six additional fabs around the facility. Initial plans for this expansion were developed before the Fab 6 groundbreaking, in line with one of TSMC's basic strategic principles — cluster fabs to minimize redundant support facilities and maximize economies of scale (Fig. 1).
Construction groundwork
Fab 6 was TSMC's first green field site and one of the first manufacturing facilities at the new Tainan Science-Based Industrial Park (TSIP), which was created by the Taiwan government when it became apparent that Hsinchu Science Park would soon be filled. Naturally, building in a new industrial park brings some obstacles with it. At TSIP, TSMC was able to work closely with the government to resolve most of these issues beforehand and in a positive manner, with minimal cost and technical impact.
The Taiwan government's proven commitment to the semiconductor industry encouraged TSMC to begin construction as soon as possible. TSIP's infrastructure was still developing, but there was a large and extremely talented labor force from which to draw. The supplier infrastructure that TSMC had developed in north Taiwan provided powerful resources for the southern local area, and many key vendors agreed to set up offices on site as well.
 Figure 2. Worker loads a pod of 300mm wafers into processing equipment on Fab 6's 300mm pilot line. |
Being among the first IC companies in TSIP gave TSMC the luxury of looking beyond a single immediate fab to plan additional manufacturing facilities and supporting infrastructure. As a result, along with the capability and flexibility to construct several additional TSMC facilities in the south, the company could also encourage faster development of the TSIP infrastructure.
Being among the first companies to move into TSIP was also advantageous from a personnel standpoint, as many engineers from the Tainan area who worked in Hsinchu had a strong motivation to transfer to Fab 6, and there was little competition for local labor resources. When fully staffed and loaded, Fab 6 will employ more than 2000 production and engineering personnel and a support staff of 320.
Other issues also had to be considered. First, it was important to TSMC that it did not have to buy land. Land is even more expensive in the south of Taiwan than in the north, so a long-term lease of government land significantly reduced up-front costs. Second, environmental considerations can sometimes delay new plants for years. TSMC, a company that routinely exceeds US and Taiwan environmental and safety standards, worked very closely with local residents to ensure that every issue was settled to the satisfaction of all interested parties very early in the process.
Building challenges
As the largest fab TSMC has built, Fab 6 faced some challenges at the beginning of construction. One was the soil condition in the area. A thorough study confirmed that the soft soil base and the local risk of earthquakes necessitated a vibration control plan. Engineers designed deep concrete pilings to minimize and dampen high-force, low-frequency ground vibration typical of an earthquake. This design met earthquake tolerance goals, and proved the right approach during a medium-sized earthquake in late 2000 that resulted in no damage to the facility.
TSMC engineers were also challenged by the large plant size relative to the short construction window. The cleanroom construction timetable and the aggressive tool installation schedule mandated that the cleanroom be built simultaneously with the fab shell and support buildings. Normally, a cleanroom would be built slowly to minimize residual construction-caused contamination to the low levels needed for pre-production and the even lower levels essential for production. Building the shell and the cleanroom at the same time meant taking innovative approaches to limiting contamination.
 Figure 3. Technician loads 300mm wafers into processing equipment. |
This was accomplished by redefining how a fab should be built. Rather than dividing the fab into major sections like the shell and cleanroom, engineers divided it into four sections, each a self-contained module that included part of both the shell and the cleanroom. This was essentially a form of modular construction, although prefabrication was limited. Most work was carried out on site, using a modular philosophy. A key tool in minimizing contamination was the use of plastic screening to enclose and isolate the cleanroom from the shell during construction.
TSMC also had to get creative in defining the wafer fab configuration. Integrated fab designs try to maximize the utilization of airflow to ensure a clean environment, and this lengthens the time required to build a wafer fab. Engineers designed the Fab 6 system to move air down through the floors, out to the sidewalls, then up into the HEPA filters mounted in the plenum chamber floor (which is part of the cleanroom ceiling).
Once the wafer fab portion of construction was completed, the cleanroom was isolated from the surrounding areas. That enabled the company to start cleaning and preparing for pilot line production.
Production payoff
Plant cleanliness contributes to high yields. The approach TSMC took during production allows it to maintain Class 100 cleanliness within the ballroom. All processing equipment is environmentally isolated from the ballroom via minienvironments, which maintain Class 0.1 cleanliness at the wafers. The entire process uses cassette-to-cassette handling to eliminate any wafer contact with the external environment (Figs. 2, 3).
 Figure 4. Example of 300mm automated materials-handling system (AMHS) in Fab 6. Red pod at right contains wafers using copper interconnects. |
Exploding demand for capacity early in the year 2000 placed the fab under increased pressure to ramp up very quickly to a higher wafer volume. By last October, Fab 6 had driven volume to 23,000 wafers/month from 4000 wafers in March. The ultimate goal is 60,000 wafers/month, a level never before achieved by a 200mm fab.
Key to the fab's quick success was focusing the construction process on important quality considerations. Also, effective processes were standardized and implemented across the entire fab. Another aspect of the plant's success has been the use of intrabay automation and automated materials-handling systems (Fig. 4).
The grand opening for TSMC Fab 6 was held on March 30, 2000, two months after starting the first wafers through the 200mm line. By early 2000, many of the tool sets required for 300mm were sufficiently developed to add a 300mm pilot line to Fab 6 plans, which enabled the company to establish tool compliance to process technologies, and to evaluate production changes and solutions for the automation of volume production handling.
Rapid deployment of a 300mm equipment set required minimal changes. While the 300mm pilot line occupies a large percentage of the Fab 6 ballroom, this room was already set aside and the addition of new equipment caused no disruption of 200mm production. Initially, the pilot line used 0.18µm CMOS technology, but TSMC has since become the first foundry to characterize 300mm chips using 0.15µm and 0.13µm all-copper processes.
300mm tool installation started June 2, 2000 (two months after Fab 6's dedication), with a goal of delivering fully functional chips by the end of 2000. TSMC achieved that target in December 2000, delivering the foundry industry's first functional 300mm wafers to customers, and setting an industry benchmark for the cycle from tool installation through first silicon. Managing tool development and insertion into the line will allow Fab 6 to have nearly 1000 sets of manufacturing tools on-line when it reaches full volume later this year.
The most encouraging footnote to Fab 6 is that TSMC will be able to extend its success into the 300mm line and into all its future fabs. Equipment installation in Fab 12 is near completion in Hsinchu (Fig. 5); Fab 14, across the street from Fab 6, will begin production sometime in 2002, depending on economic conditions (see Fig. 1).
Nun-Sian Tsai received his PhD in materials science from MIT in 1983, and then worked for AT&T Bell Labs. Tsai joined TSMC in 1989, and has held various positions at the company, including R&D manager, Fab 1 and Fab 4 director, and VP of operations at Vanguard International Semiconductor Corp., a TSMC-affiliated company. He is senior director of TSMC's 300mm pilot line project. TSMC, No. 121, Park Ave. III, Science-Based Industrial Park, Hsinchu, Taiwan 300, ROC; ph 886/3-578-0221, fax 886/3-578-1546.