1998: The year in review
from Staff Reports
Nashua, NH — Cleaner cleanrooms, the development of standards, and an emphasis on airborne molecular contaminants are some of the contamination control highlights of 1998. The year also saw significant developments in semiconductor manufacturing, with the FDA and the pharmaceutical industry, and in the area of electrostatic discharge. Watch for these topics to make headlines again in 1999.
As reported in 1998, more and more companies are manufacturing their products in controlled environments to satisfy users who want products made to the same standards they adhere to. Genzyme Tissue Repair in Cambridge, MA, raised the mark for culturing services this year and made headlines when it provided its trademark Epicel skin grafts for an eight-year-old Texas boy who suffered burns over most of his body. The Epicel skin grafts are produced through aseptic processing in Class 100 hoods. Genzyme officials say their cleanrooms are about 1,000 times cleaner than a hospital operating room.
An industry trend last year was toward “cleaner” cleanrooms in response to the market-driven demands of wafer fabrication. For example, E/G Electrograph Inc. (Carlsbad, CA), upgraded its Class 10,000 cleanroom to meet Class 1,000 certification standards to reflect more stringent particulate-sensitive environments needed for wafer fabrication. Pushing state-of-the-art means some companies can put together components and end products in a cleaner environment, which translates to a bigger sales advantage.
Sometimes technologies overlap. With changing markets and technologies, there should be more collaboration between the semiconductor and the pharmaceutical side of the cleanroom industry, according to Alvin Lieberman, a consultant for Powder Measuring Systems Inc. (Fremont, CA), who called for sharing of data between the two industries. Already, there are hybrid cleanrooms, like the one at Affymetrix, a biotechnology firm in Santa Clara, CA, where research involving DNA and RNA on silicon chips requires the cleanliness levels of a semiconductor cleanroom as well as concern about microbial contamination commonly found in the pharmaceutical industry. Also, the National Aeronautics and Space Administration (NASA) is using both technologies in its collection and storage of Mars soil samples. While some industry officials claim that cost is the prohibitive factor in combining technologies — why build more cleanroom than is needed, they argue — Lieberman says money could be saved if the problem under consideration has already been solved by the “other half” of the industry.
As cleanrooms upgrade technologically through research and development, the standards to which cleanrooms are built change. For four years, the International Organization for Standardization Technical Committee, ISO/TC 209, has been hammering out its draft international standards that can serve as a blueprint for building controlled facilities worldwide. The draft standard includes ISO/DIS 14644-4, Cleanrooms and associated controlled environments-Part 4, a non industry-specific document outlining the requirements for the design, construction, and startup and qualification of cleanrooms and clean air devices.
This document differs from 14644-1 and 14644-2. The draft is the product of ISO/TC 209 Working Group 4, which used two guidelines, the Institute of Environmental Sciences and Technology`s Recommended Practice-12 and CEN 243, as a starting point. Richard Matthews, chairman of the ISO/TC 209 Committee, commands the new document for its global nature, and says it “provides an opportunity to put in place a truly international standard.”
The draft document does not prescribe definitive technological or contractual means to meet requirements. Guidelines for specific cleanroom applications, fire regulations and process-driven safety issues are still dictated by national and local codes. Industry officials are confident that the documents should be accepted by cleanroom communities. ISO nations can vote and suggest changes until January. Then, there is a 60-day stage where it is either voted down or adopted as a formal standard. ISO/TC 209 officials are confident the document will be finalized in its final form.
But Fed-Std-209 isn`t replaced yet. At the IEST`s executive board meeting in April, the board decided to allow IEST Working Group 100 to make final recommendations to the General Services administration, regarding the future use of the standard. Working Group 100 was to meet again in November, after press time.
Airborne molecular contamination
Airborne molecular contamination (AMC) became an increasingly important concern in 1998, pushing the frontiers of investigation into methods for measuring and controlling its effects in the fab and in the cleanroom. The National Technology Roadmap for Semiconductors proposed AMC as the next technical challenge in achieving and maintaining low defect rates on microelectronics devices. Proposed methods for controlling AMC range from nitrogen purging from front-opening unified pod to fab, and the use of specially treated chemical filters in the air system, in minienvironments, and at the tool. AMCs can be measured and filtered using existing technologies, but cleanrooms of the future may need to be specifically designed to control AMC.
Milestones in the AMC control process include the 1997 National Technology Roadmap for Semiconductors, published by the Semiconductor Industry Association, which includes figures on appropriate levels of AMC. IEST`s Working Group 31, founded in May 1996, is trying to standardize outgassing methods for cleanroom materials. The first part of the Recommended Practice provides an analysis of materials used in cleanrooms. It will evaluate outgassing properties and their effects, without specifying limits for applications, which vary widely. WG 31 is developing a standardized method that can be used with any system.
Other groups are either working on or have developed industry-specific standards for semiconductors, disk drives, biotechnology and aerospace. The International 300mm Initiative (I300I) is working on a method for real-time monitoring based on surface acoustic wafer (SAW) microbalance sensors, coupled with cold stage time-of-flight secondary ion mass spectrometry (TOF-SIMS). The SAW technology was developed by Femtometrics of Irvine, CA, for NASA. SAW sensor/TOF-SIMS technology has been used by Intel for the past three years in an ongoing project of mapping its fabs. The company has its test program and is combining its efforts with I300I in an attempt to have the methodology adopted as one of the options for a standard.
The concern about AMC and the various group efforts to create standards led the ISO/TC 209 committee — charged with overall cleanroom standards worldwide — to hold a meeting concurrent with the IEST gathering in Phoenix in late April. A new working group, WG-8, was charged with developing standards, a difficult task calling for harmonizing differing standards across divergent industries. Basic steps toward standardization include the need to start with a standardized terminology. The group expects input from Semiconductor Equipment and Materials International, and the International Disk Drive Equipment and Materials Association.
Guidelines from the Food and Drug Administration (FDA) suggest that the pharmaceutical and biotech industries consider using container and closure integrity testing as an alternative to sterility testing for monitoring product shelf-life integrity. The agency released a six-page proposal that was intended for industry comment, and was marked “not for implementation.” Yet, the report was widely circulated. The FDA recommends that the alternative to sterility testing as part of stability testing programs, could result in replacing traditional sterility tests with a container and closure integrity test.
The American Glovebox Society (AGS) held its annual conference in July and touted a warm-up in relations between the pharmaceutical industry and the FDA. The FDA and industry have increasingly cooperated in establishing manufacturing guidelines that help reign in cost of facilities and products. At the conference, AGS also issued three guidance documents, including a second revision of its glovebox guidelines and two standards of practice covering design and fabrication of glove bags and the applications of linings to gloveboxes.
This year the FDA continued revising its aseptic processing guideline in response to repeat deficiencies in current Good Manufacturing Practices (cGMP). The most common cGMP inadequacies in 1997 involved lab controls, records and process controls. The FDA guideline was originally published in 1987 as a non-legal means to help companies comply with cGMP regulations for drug products. But an FDA working group started updating the document in response to advances in technology and left out issues such as personnel practices and cleanroom design, which are a large part of the updated guidance, which is expected to be published in 1999.
The Electrostatic Discharge Association of Rome, NY, will publish guidelines for controlling electrostatic discharge (ESD) in 1999. These will focus on designing a cleanroom facility with ESD and electrostatic attraction considerations, and will identify equipment and processes that can be used in a static control program, bridging the gap between ESD and cleanroom technology. The ESD Association in 1998 approved the release and publication of five standards documents that cover ESD and electrical overstress resulting during basic manufacturing processes. Three of the documents are full standard test methods covering garments and work surfaces; the fourth is a draft standard test method for soldering and desoldering tools; and the fifth is a draft standard practice providing measurement techniques to determine ion balance and charge neutralization time for ionizers in actual use locations at set intervals.
Judy Keller is a freelance writer in Milford, NH.