Former sneaker factory gets new sole

Start-up builds three cleanrooms for 6-inch wafer fab

by Mark DeSorbo

If the walls could talk, the 23,000-square-foot building would speak of Volkswagens and Converse sneakers. There would also be some chatter about the new inhabitants of this building, for the V-dubs and Chuck Taylors no longer tread here. Instead, a new start-up has transformed the facility to manufacture its telecommunications devices, enabling Telephotonics (Wilmington, MA) to take its place in the evolving “Optical Valley” of Massachusetts.

And the $500,000 renovation of the recently acquired space was rather miraculous, for Telephotonics managed to install three cleanrooms and begin testing its 6-inch wafer fab, the platform for its optical attenuators and channel monitors, within six months, says Mehrdad Namin, vice president of operations.

“The 6-inch wafer is pretty unique for optical components,” he adds.

As he walked through the maze of cubicles, some of which were newly settled, Namin pointed to a dormant softwall cleanroom. “This is where we did some experimental work, while we were building the cleanrooms,” he explains.

“The laminar flow hoods gave it the cleanliness.”

An in-house project team and contractors from Controlled Environment Systems (Mansfield, MA) designed and built the three unclassified cleanrooms, which are the equivalent of ISO Class 6 environments, and will be outfitted with ISO Class 5 minienvironments.

Tom Allard, a process engineer, at work in a Telephotonics cleanroom that will have ISO Class 5 minienvironments installed to house tooling.
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A door adjacent to the unplugged softwall cleanroom leads out into a hallway, and directly across is another door to a service chase, where air from 5,000 square feet of unclassified cleanroom space is exhausted through floor-level vents. The chase is also outfitted with gas and chemical lines, Trane compressors, humidifiers from National Environmental Products (Quebec City) and exhausts for biological safety cabinets and fume hoods.

Around the corner from the service chase is a development lab. It is equipped with optical benches, also known as anti-vibration tables, which absorb tremors from nearby Interstate 93. Within that room is a door to the changing area. Cleanroom personnel must don suits, hairnets, hoods, eye protection, masks, booties and gloves.

The changing room leads into the first cleanroom. Inside, Jim Hughes, device fab manager, was involved in various stages of the photolithography process, using a Karl Suss mask aligner to survey photoresist patterns.

“Mostly what happens in this room is photolithography, plating, wet etching and soon dry etching,” he says. “We're collecting data with three lots of wafers we are working with now. We are testing the lots so we can find weaknesses, and then work out the bugs before we go to low output.”

Jim Hughes, device fab manager, evaluates the numerous production processes, saying operations are presently at the data collection stage. Telephotonics, however, has been producing more than 1,000 wafers per day.
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A unique aspect of the cleanroom is what the ISO Class 5 (Class 100)-performing fume hoods contribute. Because they circulate 1,200 cubic feet of air per minute, additional airflow devices are not needed, saving energy costs, Hughes says.

A door within the first cleanroom provides access to the second cleanroom, which the company says is also on par with an ISO Class 6 (Class 1,000) environment. That space is slated to have ISO Class 5 softwall zones installed to house the automated tools that produce Telephontonics' “OASICs,” optical application-specific integrated circuits.

Cleanroom temperatures are maintained at 68 degrees Fahrenheit ±4 degrees, while humidity in the process cleanrooms is ±2 percent.

A third ISO Class 6-level cleanroom, which can be seen through windows in the other controlled environments, does not have humidification controls. It houses two sputterers as well as a cassette-to-cassette system that transfers up to 25 wafers at once.

OASICs can be integrated into standard semiconductor tooling, which reduces costs and increases the functionality of dense wavelength division multiplexing (DWDM) optical subsystems for the metropolitan telecommunications networks, says Fadi H. Daou, co-founder and vice president of corporate strategy and marketing.

Optical networks, Daou says, are often filled with discrete, single-function components, much like the transistors and diodes of 1960s semiconductors. Telephotonics' technology, he explains, implements those components by employing highly integrated, tunable optical circuits on a single substrate using a high-yield manufacturing process.

OASIC technology, he says, enables a component rack to be compressed onto a single chip. The fabrication process utilizes standard lithography to imprint a wide variety of passive optical elements onto an integration platform in a single fabrication step. Elements such as tunable filters, taps, attenuators and switches are combined to form high-level integrated optics.

“So far, we've had a positive response to what we're offering,” Daou says. “We feel we can fulfill a long-awaited wish.”

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