Megafab plans 0.25-micron processing in 1998

Megafab plans 0.25-micron processing in 1998

By Susan English

Austin, TX–“Built fast and built to last,” Fab 25 is AMD`s gateway to the 21st century, says a company spokesman. At 950,000 ft2, the total Fab 25 complex is enormous, with 86,700 ft2 of Class 0.04 cleanroom space. Working to the limits of optical lithography, Fab 25 will process approximately 6,300 eight-inch wafers per week at full build-out scheduled this summer. Groundbreaking began back in July 1993, construction was round-the-clock, and in only 13 months, the sub-Class 1 fab was up and running. The price tag: $1.4 billion. The fab began using 0.35-

&#181m technology in late 1995 and expects to go to 0.25&#181m in 1998. AMD`s involvement in the personal computer industry spans the history of PCs. The world`s second-largest supplier of Microsoft Windows-compatible processors, the company is now producing the 0.35 &#181m AMD5K86, AMD`s fifth-generation, Microsoft Windows and Pentium-compatible processor for the PC industry–a pin-compatible alternative to the Pentium.

The nearly one-million-square-foot megafab represents a huge investment for AMD. But the investment cost is eclipsed by Fab 25`s revenue potential–more than two billion dollars per year at full build-out–according to an AMD official, who places total FY95 sales for AMD at $2.43 billion. As to “future generations,” the company expects to be using 0.25-&#181m technology by 1998, and future plans call for even finer line geometries. By installing stringent temperature and humidity controls, allowing AMD to meet the future 0.18-&#181m environment and pushing wafer production to extend beyond 0.25-&#181m technology, Fab 25 was created with the idea of outliving conventional 0.35-&#181m fabs to deliver microprocessors based on fifth-, sixth- and even seventh-generation process technology. Overall design-build contractor for the fab was CRS Sirrine Engineers, Inc. (Greenville, SC). Meissner + Wurst (Anaheim, CA) was responsible for designing the facility`s state-of-the-art cleanroom.

Cleanroom construction– “Clean from the ground up”

An integral factor in the timing of the project was construction of the enormous ballroom-style cleanroom. Phase 1 consisted of construction of the first half of the cleanroom–space needed by the company in which to begin production of its 200-mm CMOS wafers. Phase 2–completion of the cleanroom–is slated for July 1. Perhaps the most notable feature of Fab 25`s cleanroom is its 0.04-&#181m classification, achieved by implementing 100 percent ULPA-filter coverage in all process areas. According to project manager Ron Rogerson, Class 10,000 conditions were maintained throughout cleanroom construction by means of temporary HEPA filters. The finished cleanroom`s integrated air-handling system keeps particle counts extremely low and exchanges filtered air every six seconds. Build Clean Installation Methodology mandated adherence to strict protocol guidelines for all construction as well as AMD personnel. All equipment and parts were tested for outgassing, and all finishes and fabrics were selected with regard to minimizing potential outgassing and ESD. Installed components received a minimum of three wipedowns, and airborne molecular sampling was performed at strategic points during construction. Huge fan towers recirculate air through ULPA filters at 85 cfm. No brass, copper or zinc parts are allowed in this wetted air stream. Says Rogerson: “We tried to put very stable ions there, components that won`t migrate or corrode easily.”

Flexibility was the first design priority for Fab 25`s 545-ft-long, 86,720 ft2 cleanroom. Modular walls were installed throughout. The fab itself is located on the third floor, the return air plenum on the second, and the bottom floor houses all pumps and motors. “We run everything up through the second floor to the fab,” says Dan Kellogg, Fab 25`s logistics section manager. “That gives us the ability to move pumps and everything around as needed–all the support functions.” Equipment, including major tools, comes into the fab clean and triple-bagged from the factory. The bags are shed a layer at a time and the next layer wiped down, as the equipment progresses along a special “10K hallway” that completely surrounds the outside of the fab. This “clean” path is a Class 10,000 hallway approximately 10 feet wide and 12 feet high and offers a semi-clean barrier all around the sub-Class 1 fab. Protocol mandates that anyone–tourist or fab employee–in the 10K area change from street clothes into an AMD-supplied building suit.

Tools will normally be installed from a “gray area” and then pushed through the cleanroom`s modular walls into the actual process area. Visibility was another design priority. Liberal use of glazed glass windows around the cleanroom and the 10K corridor also allow visibility for tours. AMD is proud of its Video Tour system, which allows customers and visitors the opportunity to take a “virtual tour” of the fab without gowning up or risking contamination. Twenty-six video cameras set up in various process areas and viewing monitors placed in various conference rooms in the administration building allow viewing of virtually every corner of the fab.

Robotics and monorail material handling systems

An “open cassette” factory, Fab 25 features an automated material handling system that provides interbay cassette delivery and storage. There are virtually no WIP racks in the fab. Wafers are moved from bay to bay via a 500-ft-long monorail–the Daifuku Wafer Transport System (Daifuku USA, Salt Lake City, UT)–an automated overhead material-handling system specifically designed for Fab 25. Its companion, the Kensington Wafer Sorter from Kensington Laboratories Inc. (Richmond, CA), moves wafers from one cassette to another and verifies their serial numbers. The transport system also stores cassettes at each bay until ready for processing. In the wet station, robots process wafers from bath-to-bath. In-line monitoring of wafers occurs at many process steps to ensure accuracy and quality. When the Phase II material handling system expansion is completed in October of `96, the interbay delivery system will include two concentric loops of monorail connected to stockers at the head of the process bay.

State-of-the-art ultrapure water system

The ultrapure water system is housed in two buildings: the Reverse Osmosis and Demineralization by Ion-exchange (RODI) building and the Ultrapure Water (UPW) building. The RODI building is located only 600 feet from the fab and contains the primary ultrapure water and wastewater treatment equipment, control room, analytical lab and offices. Process steps include DE and cartridge filtration, two-pass RO`s, two-stage vacuum degassification, ozonation contact tanks, 185 nm UV lights and mixed beds. The UPW building, immediately adjacent to the fab, houses the polishing equipment for the ultrapure water system and the secondary control room. Major process steps include ozone contact, 185 and 254 nm UV lights, vacuum degassification, polishing mix-beds and ultra filtration. The ultrapure water system is currently sized to meet a demand of up to 800 gpm, which can be expanded in 200 gpm increments up to a full build-out size of 1,400 gpm. The quality of the ultrapure water that is produced is considered to be world class. Typical values attained for key parameters include TOC levels that are significantly less than one ppb. Particles counts are less than 200 per liter at the 0.05-&#181m range, with total residues 0.04 ppb. n


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