A Clean Sweep in the Microchip Business
Felix Unger, move over. Bob Reynolds is in town.
Reynolds is San Diego’s unofficial Mr. Clean, the Pharaoh of Fastidiousness, the Imam of Immaculata.
“I never saw a particle I didn’t want to get rid of,” Reynolds said, nearly keeping a straight face.
Reynolds’ attention to cleanliness comes with his new territory. He is the recently appointed director of wafer fabrication at Applied Micro Circuits Corp. in Sorrento Valley, the county’s only manufacturer of custom-made miniature integrated circuits--those collections of impossibly tiny electronic components integral to everything from wristwatches to jet fighter radar systems.
As such, he runs perhaps the cleanest “clean room” in the local microchip business, an industry that views dust the way Superman views kryptonite. Without clean-room technology--a little-recognized part of the computer age that dates back nearly 30 years to the early days of aerospace technology--the mind-boggling advances in miniaturization taken for granted today would have been impossible.
Essential to Industry
“Clean rooms, or some form of similar technology, are essential to the semiconductor industry,” said Donald Davis, marketing communications manager for the company. “The increasing miniaturization (of circuits) depends on clean rooms.”
According to Applied Micro Circuits’ “Introduction to Wafer Fab” manual, “a single flake of dandruff dropped on a circuit would be like dumping a -sized brick into the back of your TV set. It is very unlikely that either the circuit or the TV would function after contamination like that.”
The danger is that a piece of dust or lint will bridge the gap between the thin painted wires on each circuit, shorting or grounding components and rendering them useless. In the early stages of manufacture, dust could also mar the surface of the fragile, costly silicon wafers, making them unsuitable for production into integrated circuits.
To forestall this, the company has built a facility that would cost $20 million today, Davis said, although he declined to release the actual cost of building the room four years ago. There, the company turns out about 500 chips a week for computers, jet fighter radar systems and other specially designed high-tech products.
Reynolds is a soldier in the semiconductor industry’s inexorable march of progress, striving for ever-shrinking technology manufactured in an ever-cleaner environment. When he talks particles, he is not speaking of dirt or grit, the kind of particles you sponge off the table after dinner. Reynolds’ world is almost unfathomably small, his enemies mere microns in a universe that encompasses the 5,000 square feet of his clean room.
Cleaner Than a Whistle
How clean is it? Most of the time, at least some areas in the clean room run at about Class 5, which means that in every cubic foot of air, there are only five particles larger than .5 microns. A micron is 1/1,000th of a millimeter. A human hair, for example, ranges between 30 and 200 microns in diameter.
Reynolds’ clean room takes normal, everyday air (particle count: 100,000 per cubic foot) and transforms it into the super-clean variety by sucking it through a high-tech filtration system made primarily of sensitive paper filters. Fans and air-locks keep dust from entering by blowing outward at all times. Air in the room is continuously recirculated through the filters at 70 to 100 feet per second in a further attempt at cleanliness.
Even the water has been cleansed of contaminating metals and ions (electrically charged atoms) that could mar the pristine surfaces of silicon wafers as they go through the complicated process of becoming -inch-square chips with 1 million or more transistors, resistors and diodes painted upon them.
“All water used in here is de-ionized water,” Reynolds said over the roar of the clean room fans. “We’ve taken the ions and the particles out of the water.”
But that is just the beginning. For as Reynolds will quickly note, the greatest sources of contamination in his clean room are the people who work there.
As the manual notes: “You have detergent covering your clothes, millions of cells pouring off your face and hands constantly, dust on your hair and face, oil on your hands, lint under your nails, and pounds of salt water (perspiration) seeping from your skin every day. If you smoke, you have hundreds of carbon particles in your breath for several hours after each cigarette.”
Kicking Up Dust Storms
Worse yet, any time a clean room employee sets himself in motion, he kicks up a dust storm of circuit-ruining particles that would be strewn about the room were it not for the head-to-toe “bunny suits” worn in the nation’s 514 semiconductor industry clean rooms.
According to a “Clean Room Primer” produced by Connecticut-based Liberty Industries, a clean room technology firm, moving from a sitting to standing position (or vice versa) releases 2.5 million particles larger than .3 microns every minute. Walking across the room at 3.5 miles per hour releases 7.5 million particles per minute.
“If you think about it,” said Reynolds, who clearly has, “every time you take a step you generate particles. And if you have a sunburn, it’s even worse.”
All this speck-shedding is clearly unacceptable to an industry that depends so heavily on tidiness. And so there are rules--of behavior, of dress, of personal hygiene--that govern the clean room environment like a Big Brother.
In the clean room, one will not find food, drink, smoking, open-toed shoes, hand lotion, pancake foundation makeup, powder-based make-up, mascara, fuzzy sweaters, erasers, unclean hands, skin ailments (that are not reported to a supervisor) or sunburns.
Because lunch has a knack of finding its way out of one’s mouth and into a clean room, “a general habit is, after you’ve been on break, take a drink of water,” Reynolds said. “It’s a good habit.”
A reporter preparing to enter the clean room sanctum was ordered to abandon the tools of his trade. Only “clean room paper” of thick fabric-like quality is allowed inside, for it releases far fewer particles than ordinary notebook leaves. Similarly, felt-tip pens, retractable pens and lead pencils were left behind. Ballpoints only in the clean room.
Dressing for the Job
Workers suiting up for their shifts follow a carefully scripted dressing routine. (The company runs work shifts about 20 hours per day during the week and about 12 hours each day on the weekends.) Hoods and face guards are put on first, followed by full-body suits that go over street clothes, booties and gloves. Eye guards are worn to prevent damage from splashed acid.
Booties are then cleaned by stepping on a “tacky-mat,” a sticky doormat that strips the bottoms of dust. They pass through an air-lock that blows more particles back where they belong.
The facility itself is a series of smaller rooms containing sophisticated electronic gadgetry, bubbling water baths, microscopes, ovens, wet and dry work stations, and more gadgetry. Yellow light glows from the ceiling of one room where photosensitive layers are applied to the wafers. The roar of fans and air ducts causes everyone to raise their voices a bit.
Employees never touch the round black wafers, picking them up with special “limited access tweezers” and “vacuum wands.” Pages in the manual are taken up with the procedures for handling and processing wafers, but still 2 of every 24 are are lost due to handling errors, according to the guide. “This results in a loss of $20,000 per week!” the manual notes.
“It’s a much more stressful environment” than in other jobs, Reynolds acknowledges. “If they’re handling a lot of wafers, they’re handling $50,000 at a time. They drop that, boom, they drop $50,000.”
Still, there are side benefits. “I enjoy (it) because I’m from Los Angeles and there’s so much pollution,” said Bill Anton, a wafer fabrication operator. “Here, I can come in and breathe.”
Strives for High Yield
The company strives for a high yield of usable chips from each wafer. The results can run as low as 20% or as high as 80%, Reynolds said. But with people the main cause of dirt, Reynolds knows that he can always make his operation cleaner. Someday, the workers will wear glass bubbles like spacemen and suits made of Gore-Tex fabric with millions of tiny pores too small for particles to escape through.
And beyond that, robots may inhabit at least parts of Reynolds’ clean room, their particle-free limbs working in dustless serenity, uncontaminated by human cells, sweat, breath or hair.
“No particle is insignificant from a cleanliness point of view,” he said. “Cleaner is better.”
Bob Reynolds can dream.
