In Battle Against Haze, Rave Wields Rhazer
Rave LLC has developed a prototype haze removal system, Rhazer, which can break down haze buildup on a reticle without removing the pellicle. "We are entering a whole new market space, and we have a working prototype," said Rave marketing manager Michael Archuletta.
David Lammers, News Editor -- Semiconductor International, 7/15/2008 11:37:00 AM
Rave LLC (Delray Beach, Fla.) announced today that it has developed a system to remove what has become a vexing and expensive problem for fab managers: haze buildup on photomasks.
The Rhazer system comes from a company that pioneered the use of atomic force microscopy (AFM) for the repair of mask defects. For the haze removal system, however, Rave is disclosing little about the technology it uses to break up the crystallize film due to pending patent applications. At a press conference at SEMICON West, CEO Barry Hopkins said Rhazer is “an extension of laser technology” that uses “no chemistry, in a dry-to-dry approach.”
“We are entering a whole new market space, and we have a working prototype,” said Rave marketing manager Michael Archuletta. Customers are evaluating the prototype system at the Delray headquarters and, by the first quarter of 2009, the system is expected to be in pilot production, he said.
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| Crystalline formations called haze require frequent mask cleanings, during both processing and after storage. |
The Rhazer system will ease the problem of sending masks out for repeated cleanings by removing the haze layer within the fab itself, and it will do its work without removing the pellicle and with no damage to the absorber materials, he said. Pellicles are permeable and draw ammonium from the air during storage — a problem that worsens during periods of high humidity.
Haze has become a major hassle for fab managers. Masks must be taken off for cleaning after 1000-5000 exposures, often forcing fab managers to have at least one extra set of critical masks to maintain a smooth production flow. “If you have to buy two extra levels, that will cost $150,000,” he said.
Haze is never completely abolished: It begins to reform soon after cleaning. Rave doesn’t have data yet on reformation rates after a Rhazer treatment. Ken Roessler, director of engineering at Rave, said, “We know our system does the job, and does it well and fast. Ours is a sulfur-free process, so it makes the mask less susceptible” to haze reformation, he said.
Rave has developed business-case scenarios that show that large foundries spend tens of millions of dollars on repeated mask cleaning steps to battle haze residues, with damage often occurring while the mask is shipped back and forth from the mask shop.
“It is a time-consuming process [to wet clean masks] with a 72-hour turnaround. The game is to see how many wafers you can print before you have to stop. A foundry might process 2000 wafers and then have to stop [to clean haze from the reticle]. If the customer calls and needs chips right away, that presents a problem,” Archuletta said.
The Rave Rhazer solution provides fabs with a non-destructive process that breaks the haze down so the mask can be put back in service. “It gives the customer a way to live with it. It doesn’t completely remove the haze, but it allows the reticle to get right back in the wafer line after one shift [8 hours].” he said.
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