Semiconductor fabs drive changes in cleanroom construction

Semiconductor fabs drive changes in cleanroom construction

By Lisa A. Karter

Of all the industries that require cleanrooms, the semiconductor industry requires the quickest built, newest technologies and pushes the envelope for cost savings. With the advent of 300 mm wafers, the semiconductor industry is looking for ways to chop costs in one of the most expensive parts of the fab — the cleanroom.

“The whole focus is to reduce the amount of area under a filter,” says senior project architect Dana Watts of Symmes, Maini & McKee Associates, an A/E firm based in Cambridge, MA. “Cleanrooms are getting smaller while the service corridors where the tools actually sit have gone from six feet to up to 20 feet.” The size decrease is based on operational cost savings and the growing popularity of minienvironments.

Most of the changes to cleanrooms in the last ten years have come about from design, operation and component changes. Room layouts in 1987 were much different than today`s. Watts describes older microelectronic cleanrooms as having a clean aisle and a service aisle. The cleanroom would consist of 12- to 14-feet clean areas flanked by smaller service chases about 5- to 6-feet wide. Other common features, according to Watts, are the Class 100 cleanroom, full cleanroom garment systems — coveralls, hoods, booties, gloves, etc. — and, low wall-mounted return air grills as well as studded walls.

“What`s come about since then is that the component industry has grown from something akin to a cottage industry into vendors who offer floor, wall and ceiling products who also do turnkey construction,” adds Watts. Turnkey construction and prefabrication of cleanroom components is much more common today because it`s generally cheaper to build a prefab cleanroom, and there`s a push on microelectronics fab owners to get their products to market as quickly as possible.

Moving toward design/build

Several architects and contractors have labeled design/build (D/B) an emerging trend because of its ability to offer a single point of responsibility for designing and building a cleanroom, or any other type of facility. Theoretically, this type of delivery system should decrease the amount of haggling between an architect and contractor because each is under the same contract.

Mike Moore, president of general contractor Southland Industries (Long Beach, CA) says half of his company`s projects are design/build and the balance are design/assist. “Design/build is our preferred method. We can accomplish the design faster and more efficiently,” he says. “What we try to achieve is integrating the design and the build because that is, without question, the most cost effective way to erect any one of these systems. The integration allows for a huge improvement in field productivity.”

However, Moore and William Gower, senior vice president/regional manager for McCarthy (San Francisco) believe that it is up to the owner to determine what delivery method he or she wants. Says Gower: “It really comes down to what the client is looking for. We will provide whatever project delivery system clients require. Clearly defining a project is key to its success.” However, Gower cautions facility owners not to be misled into believing that D/B will remove them from the responsibility of the design. “Someone has to define what`s required,” he adds. Once the scope of the project is clearly defined, then “either delivery system works,” he says.

Timothy Loughran, manager of business development for Performance Contracting, Inc. (Richmond, VA) adds that with design/build on the upswing, more and more performance responsibility is pushed onto the subcontractor because “value, engineering and constructability are brought up further in the process.” Although design/build offers to solve many problems, “it isn`t a panacea to end all problems,” adds Watts. “It`s not necessarily the right method of delivery for everybody.”

Trends & predictions

Minienvironments are the biggest, hottest trend in the microelectronics cleanroom today and many are being designed into 300-mm fabs. “As fabs get more and more expensive,” says Loughran, “owners are looking for ways to decrease cost and minis are a good way to do that.” Minienvironments can help decrease costs because they provide a Class 1 environment for process tools, therefore, the cleanroom itself does not necessarily require a Class 1 environment, but could be a Class 100 or Class 1,000 room. Cost savings of not using a Class 1 ballroom-type cleanroom are already calculated in the millions. Adds Watts: “In microelectronics facilities, more automated product handling and minienvironment interfaces allow energy savings.”

Craig Ludwig, vice president of strategic planning at CleanPak International (Clackamas, OR) says, “I think that definitely as 300 mm and 400 mm technologies progress, their process tools will have self-contained minienvironments and potentially the cleanliness levels around the tools can be reduced.” Minis offer a cost saving for fab owners, but also a production problem for maintenance — if the room is less clean than the minienvironments how will it be serviced? Within the next few years, this question will be addressed.

As in most areas of the cleanrooms industry, the services sector has gone through an evolution during the past 10 years that`s meant a surge in opportunities for independent consultants, trainers, and cleanrooms cleaning/maintenance firms.


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