Ed’s Threads 070216
Musings by Ed Korczynski on February 16, 2007

AMAT plasma doping tools likely
As recently reported in WaferNews, Applied Materials has decided to stop developing new beam-line implant tools. Already developed tools will still be supported, and manufacturing will shift from Horsham, UK to Austin, Texas, so if you want to buy another new 300mm beam-line implanter to add capacity to your production line, Applied will still happily sell you one. This is by no means the end of the company's implant technology development—in fact, it likely tells of the imminent deployment of technology patiently developed over the last 18 years: plasma doping.

Michael Current, renowned expert on doping and gate-stacks and director of technical marketing for Frontier Semiconductor, explained to WaferNews that during his tenure at AMAT in 1989, he started a plasma immersion program with Nathan Cheung and his students at UC Berkeley using Applied’s sponsorship and equipment. "We did a lot of early doping R&D;, and it leaves the option open for Applied to re-enter the doping business,” he said. Current was also with Silicon Genesis when that company commercialized the plasma immersion ion implantation (PIII) of hydrogen for SOI wafer production, and not-coincidentally when Applied Materials again worked on hardware.

Plasma doping chambers look a lot like single-wafer PECVD hardware, such as is found on an Applied Materials’ Centura platform. The wafer is immersed in an isotropic plasma, and energy pulses drive the ions into any exposed surfaces. All surfaces across the whole wafer are exposed at once, and very high doses can be provided without saturation.

There are inherent reasons why ITRS scaling of structures has led to inherent challenges with standard beamline implant technologies, particularly for high-dose implants. “Some people are reportedly using the Varian tool to do high-dose implant, though there is always the sputter-limiting effect,” explained Current.

Rumors that Varian had recently captured the Intel implant business away from Applied may be part of the backstory. In an official press release, Mike Splinter, Applied Materials president and CEO, said that, "Unfortunately, the implant equipment business has changed over the past few years and moved towards commoditization and projected financial performance does not warrant further expenditure in next-generation beamline implant products."

Jim Cushing, chief marketing officer for implant at Applied Materials, declined to talk about the company's next as-yet-officially-unmentioned doping technology, but provided WaferNews with a general perspective on its likely first applications. “From an industry perspective,” commented Cushing, “non-beamline will probably first be used for poly doping for DRAM, then poly doping for logic at 45nm, and then ultrashallow junctions and 3D devices at 32nm.”

When I interviewed Applied Materials’ Chairman Jim Morgan 10 years ago, he explained that, “What we do is spend dollars when we see an opportunity to commercialize technology where we have a market requirement, the technical concept, and the talent to work on it. That really drives our investment programs and we’ll spend what we need to in order to support that. If we have a good product, we’ll realize several hundred million dollars of business, so the return on investment will come.”

Either there’s a completely amazing mystery process already developed yet hidden in a lab in Santa Clara near the intersection of Central and Bowers—or, as is far more likely, we are about to see the payoff of a patient 18-year investment. When Applied Materials started work on plasma immersion, the original target application was trench doping for DRAM capacitors, though it was never ultimately deployed. Now, protruding finFET structures are sort of the 3D conceptual inverse of embedded trenches, and the general challenges of high-dose implants mean that it’s time for plasma doping to be used in mainstream manufacturing…probably.

—E.K.
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070216: AMAT plasma doping tools likely

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