Market drives need to make cleanrooms `cleaner`
By Myron Struck and Kathleen Vail
Making a cleanroom “cleaner” than industry standards may lead to competitive advantage. The cleanroom should be as clean as it needs to be to handle the manufacturing processes, of course, but some companies are finding that standard is just not good enough.
E/G Electro-Graph Inc., an ISO-9001-certified subassembly manufacturer in Carlsbad, CA, recently released the findings of its routine, six-month cleanroom inspection, saying that its Class 10,000 cleanroom met Class 1,000 certification standards, upgrading a full order of magnitude. The results, according to the company, reflect “more stringent particulate-sensitive environments” in response to the demands of wafer fabrication.
Electro-Graph packages and seals subassemblies and replacement parts at benchstations.
The conversion from Class 10,000 to Class 1,000 cost about $50,000, says Electro-Graph President and CEO Dan Hacker. To make the conversion, says Hacker, the company built an alcohol wetbench with charcoal filtering for a final cleanup on the product. Also, it installed a nitrogen purge bagging system.
Bob Spector, speaking as technical vice president for contamination control at the Institute of Environmental Sciences and Technology (IEST), says manufacturers have to do what is necessary to push the state-of-the-art.
“The line-widths have gotten so small that you can`t rely on your own environment to clean a tool that has been produced in an ambient environment,” Spector says.
Upgrading cleanroom certifications means that you may be able to put together the critical manufacturing components as well as end products in a cleaner environment. Manufacturing a component may require a Class 10,000 room, but the piece of equipment manufactured may be headed into a Class 1,000 or better room, forcing the recipient to take steps to ensure additional cleanliness.
“If you`re doing 0.18-micron linewidth, for example, your ability is going to be limited to check for the cleanliness of equipment being used to craft that piece,” says Spector. “The room itself is not the end. The largest contributor to contamination in semiconductors are processed tools, the processes and the chemicals.”
Bob McIlvaine, a market analyst with The McIlvaine Co. (Northbrook, IL), says that the cleaner the room, the larger the sales advantage a component manufacturer has.
“Cleanliness is important to the people receiving the product,” he says. “Many times [the product] will be used in another cleanroom. Reliability is the issue.”
McIlvaine estimates that the costs of moving from one cleanroom class level to the next go up five to six times.
Michael A. Fitzpatrick, head of “Considerations in Cleanroom Design Working Group Subgroup 2: Installation of Cleanroom Production Equipment,” says that it is logical to presume that most manufacturers want the components fabricated in rooms that are similarly rated to the ratings they themselves must use, and most require Class 100 or Class 10 areas for critical stages of fabrication and packaging.
But exceeding the requirement leaves Fitzpatrick with mixed feelings. As an IEST representative, he says he would “caution against” investing capital to obtain a level of cleanliness not driven by process needs.
The IEST, Spector says, has taken no steps to promote industry-wide requirements, letting the market drive the process instead.
“To write a recommended practice,” Spector adds, “you want to have a good mix of users, suppliers and manufacturers” agreeing.
Myron Struck is the Washington bureau editor for CleanRooms. Kathleen Vail is a freelance writer in Alexandria, VA.