Lawsuits prompt focus on cleanroom safety
By Myron Struck
Washington — They don`t occur often, but lawsuits concerning worker safety in cleanrooms tend to catch the attention of the industry.
Take the Zilog incident. It happened in Nampa, ID, in the mid 1990s. The employees of Zilog Inc. claimed their lives were endangered by the practices of the semiconductor chip-making corporation. Some 900 incident reports were recorded at Zilog`s facility in 1993 and 1994, according to an investigation by USA Today that was widely reported in January 1998. These incidents involved alleged violations of federal safety laws in cleanrooms where employees claimed that chemicals became contaminants, and air-handling equipment became a conduit for the circulation of toxic fumes. In August 1996, Zilog paid $ 2.25 million to settle the lawsuit brought by 30 past and current workers. Zilog was purchased by Texas Pacific Group in January.
And then in February 1998, an IBM Corp. facility in San Jose, CA, was the subject of an employee lawsuit charging that a cleanroom in the facility was improperly maintained, causing exposure to employees. The suit, filed by four former IBM employees and the families of five workers who died from cancer, states that workers faced “fatal levels of cancer-causing chemicals” for the better part of 30 years. The victims are claiming damages and interest for having been exposed to toxic chemical substances while working at an IBM disk reader manufacturing unit in San Jose, CA.
The plaintiffs say the cleanrooms where they assembled the disk readers only filtered particles that could have damaged electronic parts. The rooms were not equipped with a ventilation system to filter out toxic fumes, they say. Amanda Hawes, the lawyer who filed the suit, says the clothing worn by cleanroom workers protects chips from human contamination but doesn`t protect workers from the toxic chemicals at work.
IBM spokeswoman Tara Sexton tells Reuters news service that she can`t comment, since the issue is before the courts. “IBM,” Sexton states, “has a long-standing commitment to a safe working environment and compliance with all health and safety regulations and laws.”
Concern about worker safety in cleanrooms has left officials at all levels — from the corporate boardroom to watchful trade associations — scrambling to keep track of the problems and come up with solutions.
At the Institute of Environmental Sciences and Technology (IEST), which conducted its annual conference in April, the topic of cleanroom safety was turned into a seminar, with industry experts offering their best cut at resolutions.
According to Penny Van Sickle, contamination control program chair for IEST, the object of safety in a cleanroom is a combination of several things, “but protecting the people is the primary goal.”
Van Sickle, who is also a senior contamination control engineer at Fluoroware, (Chaska, MN) says that there are different standards — and concerns — in the semiconductor and pharmaceutical industries, so far as cleanroom environments are concerned. While the semiconductor industry doesn`t “really have the biohazards that may be present in pharmaceutical companies,” Van Sickle says, gasses and chemicals still present a hazard that must be mitigated.
“Reactive semiconductor gasses can be quite toxic,” she admits. “For gallium arsenide production, arsenic precursors are used and arsenic dust will build up in the piping. Exposure to arsenic long term will eventually lead to death.”
Kenneth Goldstein, a consultant with Cleanroom Consultants Inc. (Phoenix), concurs that people are the primary target of cleanroom safety. Goldstein says the people who need the protection, however, should not be limited to those in the cleanroom, but anyone working at a facility.
“Protection of the product, the tool set or the facility is secondary to protection of people,” Goldstein says. In this regard, “life safety almost always trumps other considerations.”
Goldstein, who was a lecturer at IEST events, says that the chief hazard in cleanroom chemicals comes from anything toxic, corrosive, flammable or pyrophoric. However, some attention should be given to photoresists and developers that are suspected carcinogens or mutagens.
Other gasses that present cleanroom problems include silane and diborane. Both could lead to death, even if breathed in “very low concentrations,” Van Sickle says. Today, gas systems are often made of welded stainless steel to eliminate the chance of operator error in opening up a piping system. “Fabs also have gas detectors set up in the cleanrooms that detect these toxic gases at extremely low levels,” she says. Any measurable amount of these gasses is supposed to set off an alarm.
A decade or more ago, Van Sickle says, most liquid chemicals and solvents used in a semiconductor cleanroom were handled in one-gallon glass or polyethylene containers. With operators constantly required to move materials from point to point, the opportunity for spillage, breakage or another kind of accident was great. A cracked container would force an evacuation, especially if the fumes included trichloroethane or ammonium hydroxide — particularly toxic fumes.
Worker mistakes also played a role in changing cleanroom procedures. Pouring acid into the base storage bin, for example, could cause an exothermic reaction or explosion.
Van Sickle says that open baths of chemicals in wet benches also pose a serious hazard for operator health. Some chemicals build up in the operator`s system and cause problems later. Some solvents such as toluene and benzene cause birth defects. Van Sickle says that IBM showed back in 1992 that ethylene glycols (antifreeze) can cause miscarriages.
Goldstein says that isolation and monitoring advances have led to increased safety in cleanroom environments. “First, potentially harmful substances are kept separated from people,” he says. “Second, detectors are used to monitor for these substances in areas where people may be present.” Other mitigation techniques include neutralization and dilution.
The problems have resulted in changes to procedures. Now, most chemicals are handled by a liquid chemical distribution system. Used in this manner, only 55-gallon drums or very large day tanks of chemicals are used so that individual operators are not handling the materials.
Fluoroware has developed a chemical dispensing system for 55-gallon drums so that there are individual key codes on the bungs, the connections between the dispensing hoses and the outlets for each chemical (see photo, page 1). As a result, a drum of sulfuric acid cannot be attached to a hydrochloric acid system (which would result in the contamination of the system).
Goldstein contends that no new government regulation is needed to monitor cleanroom contamination. “But this is a personal opinion,” he says. “In most cases, I suspect that government regulations come about too late — locking the barn door after the horse has been stolen.”
While the United States and western European countries have strict regulations in place, there are significant differences in how they handle cleanroom safety. U.S. companies are now looking to avert the mistakes of the past by instituting state-of-the-art-processing procedures, including quality sampling procedures.
In those regions of the U.S. that have a plethora of cleanrooms and regulators familiar with their dangers, the controls are generally more even than regions where there are more isolated cleanrooms, Goldstein says. He says that Japan, Singapore and Taiwan also have significant cleanroom controls in place. Meanwhile, Korea and China lag, he says, as does Eastern Europe.
Myron Struck is a freelance writer based in Alexandria, VA.