Sematech effort to simplify comparisons of consumables

08/01/1999

Consider the possibility of categorizing consumables into different grades, thereby transforming things like gloves and wipers from seemingly magical high tech products to easily understood and specified commodities.

In fact, there's a group effort underway to develop, as a first step, methods to characterize gloves and wipers for semiconductor users. The first goal, according to a Sematech spokesman, is an expansion of an Institute of Environment Sciences and Technology (IEST) wiper document from just covering testing to that plus characterization. An IEST group is currently updating IEST Recommended Practice CC004.2, published in 1987, on cleanroom wipers.

Beyond this initial target lies the possibility of categorizing consumables into different grades. Such a grading system would simplify purchasing. That could have implications about the price and performance of consumables far beyond the semiconductor industry. Such a de velopment is likely a year or more off, but even accomplishing the initial goal would yield contamination control benefits.

"Everyone would be using the same test methods, and hopefully then wiper comparison would be just a matter of comparing test data rather than how it currently stands, which is there are no standardized test methods that everyone follows," explains David Nobile, product development manager for wiper manufacturer Contec Inc., Spartanburg, SC.

Sematech is spearheading the effort to bring some order to the consumables jungle. IEST is also involved, as are the consortium's member companies, such as Advanced Micro Devices, Lucent Technologies, Motorola, and Texas Instruments. On the vendor side, participants include glove manufacturers Safeskin Corp., San Diego, and Oak Technical, Stow, OH. Besides Contec, other wiper manufacturers involved include Lym-Tech Scientific, Chicopee, MA, the Texwipe Company LLC, Upper Saddle River, NJ, Berkshire Holding Corp., Great Barrington, MA, and Milliken and Co., Spartanburg, SC.

To date, the glove group has developed a set of standards that semiconductor manufacturers are evaluating. Donna Di Gangi, quality manager for the scientific group at Safeskin, says that some of the parameters being tested include particulates; extractables such as anions and cations; pinholes; strength of the glove, including tensile and elongation; electrostatic discharge properties and organic matter. Di Gangi worked on the extractable and particulate measurement methods, trying to make them as sound as possible. However, the tests are destructive, and that adds a bit of uncertainty to the process.

"You're going to get varying results because each glove is going to be slightly different," Di Gangi said. "You can't really retest to see how your methods worked."

One side effect, she adds, is that manufacturing process control is highlighted. Or rather, the lack of control is highlighted. Without manufacturing consistency, any test result will be of little value, especially since the tests cannot be repeated.

On the wiper side, there are 13 or so parameters that have been under discussion. Of particular interest for cleanrooms are those involving particulates. Steven Paley, president and CTO at Texwipe, points out that wiper particulate measurements have moved from a dry test, which consisted of shaking a wiper near a particle counter, to wet methods. These in turn have evolved from using water to using low tension cleaning solutions, such as water-isopropyl alcohol mixtures. At the same time, there's been a move toward the use of scanning electron microscopes. "The tests that we've developed are certainly repeatable and we have a tremendous amount of data to show and measure that repeatability," says Paley.