A Glimpse at Semiconductor Facilities

-- Semiconductor International, 11/1/2000

Peter Singer,
Editor-in-Chief

Semiconductor manufacturing is one of the most complex manufacturing processes in the world, and the fabrication facilities built to house that process mirror that complexity. They are also huge. Consider, for example, the three winners of this year's Semiconductor International Top Fab of the Year awards: IBM in Burlington, Vt.; Taiwan Semiconductor Manufacturing Co. (TSMC) in Hsin-Chu, Taiwan; and SC300 in Dresden, Germany.

The IBM fab occupies 950,000 ft², with a manufacturing area of 421,000 ft². It employs 2500 people, including equipment maintenance, fab operations and line support engineering. TSMC's Fab 5 is somewhat smaller, but still big, occupying more than 200,000 ft² of space, with a manufacturing area of 87,000 ft². It employs close to 600 people. The SC300 fab, the world's first operational 300 mm facility, measures 5400 m² (60,000 ft²), with a manufacturing area of 1800 m² (20,000 ft²). It employs 429 people.

The complexity of advanced fabs comes about from the need to support the hundreds of advanced manufacturing tools required for integrated circuit production. Semiconductor manufacturing facilities must be designed to:

• rapidly move and track thousands of wafers (or cassettes of wafers) throughout the facility;

• provide an "ultraclean" environment;

• handle a variety of gases and chemicals (some of which are highly corrosive, toxic, flammable and/or carcinogenic), as well as deionized (DI) water;

• house hundreds of vacuum pumps and other support equipment;

• handle large amounts of gas and liquid process waste (some of which is recycled);

• use sophisticated software and computers to control the process, and collect and analyze vast amounts of data.

The complexity of an automated material handling system (AMHS) alone is well illustrated by the leading-edge system in place at IBM's Fab West in Burlington, Vt. The current system integrates 55 stockers in distributed process bays serviced by 85 vehicles traveling over one mile of interbay track with more than 20 routing devices, two dozen fire wall penetrations and two interfloor transfer devices. The AMHS system manages multiple building elevation changes to transport product to every process bay, including interfloor delivery to and from processing areas located under the main fab level.

New challenges and trends in material handling (and automation) are most obviously driven by the push to move from 200 mm to 300 mm wafer sizes. Karl Mautz of SC300 reports that the main differences between 300 mm and 200 mm factories are that 300 mm fabs are expected to have pervasive use of FOUPs and minienvironments; very high levels of individual tool automation; highly integrated factory CIM systems; automated intrabay handling systems; factory layout optimized for automation, not operators; and a significantly reduced level of operators.¹ The continued push to smaller dimensions is also creating a variety of challenges throughout the facility, from the way in which the building is designed and equipped, to cleanroom procedures (see "Keeping it Clean") to the way in which gases and chemicals are handled.

Some of the gases are manufactured on site or piped in through underground lines, while others arrive in tanker trucks or the more familiar gas cylinders. Gases are piped throughout the fab using a distribution system made up of piping, gas cabinets and panels, filters, regulators, flow meters, analyzers and numerous other components. The ability to safely and reliably deliver ultraclean gases at the process tool is the paramount concern.

Other concerns are DI water and a wide range of chemicals that, like gases, can be corrosive, flammable or carcinogenic. Some chemicals are generated at the tool (called point-of-use chemical generation or POUCG) but most of them are shipped in large containers and distributed throughout the fab using a chemical delivery system. DI water is generated at the site. Water and chemical delivery systems employ sophisticated piping, pumps, filters, particle detectors and analyzers.

The big trend with gas and chemical management is to outsource the responsibility for those operations to outside suppliers. Although all of the large gas supply companies have offered such total services from some time, the stakes are getting higher; a new company called TRiMEGA is now offering all of the required process-critical materials, systems and services (see "The Case for Outsourcing").

Similarly, there is a trend to push the responsibility for vacuum from the facilities managers to the suppliers of process tools. Roughing pumps are now being integrated into the process tool, taking them out of the basement. This not only reduces maintenance headaches for the facilities people, but allows smaller pumps because much of the foreline piping can be eliminated.

Looking to the future, the greatest facilities challenges clearly revolve around the move to 300 mm equipment. Equipment suppliers have worked hard to keep 300 mm equipment about the same size and complexity as 200 mm equipment, but the larger wafer area being processed will create a demand for more material flow (gases, water, chemicals), generate more waste, and require a higher degree of digital control. The 300 mm equipment will also have different, more automated interfaces (some including built-in buffer stations). Beyond that, as reflected in our survey of facilities managers (see "Survey Reveals Facilities Management Challenges"), the biggest challenge is simply learning how all this new 300 mm equipment works. •

Keeping It Clean During the construction of White Oak Semiconductor, the Semiconductor International 1999 Top Fab Award winner, the philosophy was to start clean, build clean and stay clean. The approach was determined at the beginning of the project during the design phase. Implementation of a build clean construction protocol started with classroom training for everyone and was continuously reinforced by monitors in the field throughout the project. The White Oak Semiconductor construction project consisted of six levels of protocol: Level 1 — Black color coding signage. Begins with groundbreaking and ends with building dry-in. General area cleaning is required at least three times a shift. Main entry is tented and consists of shoe wipe-off mats and brushes as well as gross tool wipe-down areas. No material restrictions. Level 2 — Blue color coding signage. Begins with building dry-in and ends with clean zone enclosed and top down clean complete. General area cleaning is performed after every activity or job. Additional areas for detailed materials and tool wipe down prior to entering an area are provided. Materials restricted to only 10 hours worth of work. Shoe covers, head covers, beard covers and gloves are required. Air is on. Level 3 — Green color coding signage. Begins with clean zone enclosed and top down clean complete and ends with special micro clean (also referred to as "super clean") complete. General area cleaning is continuous. Material restricted to only 10 hours worth of work and is 100% inspected. Shoe covers, head covers, beard covers and gloves, construction bunny suits, hoods and knee-high boots are required. Level 3 areas are kept pressurized with some temperature and humidity control (±5°F and ±15% RH). Level 4 — Yellow color coding signage. Begins with special micro clean complete and ends with cleanroom certification. General area cleaning is continuous. Material restricted to only 10 hours worth of work and is 100% inspected and 100% micro cleaned. Shoe covers, head covers, beard covers and gloves, construction bunny suits, hoods and knee-high boots are required. Level 4 areas are kept pressurized with improved temperature and humidity control (±1°F and ±3% RH). Cleanroom particle performance is greatly improved with exit from this protocol meeting or exceeding design criteria. Level 5/6 — Begins with tool hook-up and continues for the life of the factory. Permanent garments are issued for manufacturing and support personnel. Full and permanent pre-gown and gowning areas and procedures are in place. These include hand washing prior to gowning in all manufacturing areas. M1, M3, M4.5 are all bunny suit protocol areas. M5.5 and M6.5 areas require smock protocol. All require micro cleaning of everything that enters the clean spaces. Pressurization hierarchy exists between all the clean spaces. •

The Case for Outsourcing Air Products MEGASYS technicians perform on-site management services. (Source: TRiMEGA) Semiconductor manufacturers have been outsourcing the responsibility for installing and maintaining some aspects of the facility - most notably gas and chemical management - for some years. Now, a company called TRiMEGA Electronics L.L.C. (Santa Clara, Calif.) is aiming to provide all process-critical materials, systems and services for semiconductor fabs. A 50/50 joint venture of Air Products and Chemicals Inc. and Kinetics, TRiMEGA has secured full-scope supply contracts and collaborative projects valued at more than $115 million. "Our mission is to provide semiconductor manufacturers with process system expertise and point-of-use guarantees for all of their critical process utilities," notes TRiMEGA's president, Bob Nolan. The company, which also makes use of the capabilities of USFilter, offers design; bulk and specialty gas equipment and components; chemical slurry and distribution equipment; UPW and waste treatment equipment; installation; QA/QC; ongoing operations; and molecules for water, chemicals, gas and central utility systems. Customers can select from several approaches: financing and build/own/operate, turnkey with POU guarantee, process wastewater reclaim, total water management (recycle, reclaim, reuse), tool hook-up and "utility island." As an example, the company recently completed the gas, chemical and water systems for an optoelectronics fab in eastern Canada. The agreement, valued at $35 million over 10 years, calls for TRiMEGA to supply all the facility's bulk and specialty electronic gases and chemicals, related equipment, water and wastewater treatment systems, as well as to provide on-site management and operations. Air Products supplied the bulk and specialty gas equipment, while Kinetics provided its Mega Systems line of bulk chemical delivery systems, process piping installation and QA/QC. USFilter provided the UHP water and waste treatment systems. According to Rick Beuttel, director of fab development for TRiMEGA, the process systems in the Canadian fab were completed - from concept design to first silicon - in only seven months. Traditionally, this scope of work takes 10 to 12 months. Beuttel also points to manpower savings at the Canadian facility that started up in August. "By doing task analyses, using Web project collaboration tools and by cross training, we reduced our on-site team from 12 people to seven. Also, the owner was able to put the entire fab together with a total facility staff of four versus the traditional complement of 10 to 13 people." Another major full-scope supply project is a new fab in Phoenix, where the design/build review phase is nearly complete. At this plant, the make versus buy savings are expected to be "in the 15 to 17% range." Improved supply chain management can be another advantage. "Our relationships with the leading UHP suppliers result in preferential supply of critical components and commodities during periods of rapid industry expansion. This is critical to our ability to achieve accelerated project delivery when the lead time for stainless steel tubing is three to four months," Beuttel notes. But perhaps the greatest advantage of all is the money that outsourcing frees up. Nolan explains: "If TRiMEGA can help with financing 20 to 30% of the facility cost, it frees up more of the owner's capital to invest in wafer processing equipment so more devices can be shipped out the door once the fab starts up. There's less need to delay the buildout of the fab until later on. Plus, they're eliminating debt service." Nolan said the company is willing to finance equipment that is recoverable, i.e., a skidded water treatment plant versus UHP piping. "We can always move the skidded plant to another location if the fab ceases its operations." Bob Pragada, vice president of sales and marketing for TRiMEGA, adds: "Instead of having to commit the up-front capital to build a water plant, the owner procures ultra-pure water as a service. And, more importantly, that allows the owner to focus on running the fab instead of being concerned about the quality of the water. From a balance sheet perspective, instead of carrying these non-core assets on the balance sheet, the owner can finance part of the fab with money going from the operating budget, rather than from debt or equity-linked vehicles. This is especially beneficial in an industry where the cost of capital is higher than ours because of the higher risk and cyclical nature." 

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REFERENCES

1. K. Mautz, "Capability for 300 mm: Approaching Industry Goals," Semiconductor International , July 2000, p. 112.

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