Genus implanter process patented

Electronic News, July 1, 1996

Sunnyvale, Calif.--Genus received U.S. Patent No. 5,501,993 for its buried implanted layer for lateral isolation (BILLI) process for making retrograde wells in ICs. The process is based on the company's high-energy ion implantation equipment.

Genus has been promoting the process for years as a way to simplify IC manufacturing steps and reduce costs, principally through eliminating the need for epitaxial wafers. By enabling epi-free isolation of adjacent transistor wells, according to Genus, BILLI can eliminate one or two masking steps from current standard "million electron volt" (MeV) retrograde well processes and three to four masking steps from conventional diffused well processes.

"The BILLI structure is being used in production in the United States, and more than 10 of the world's leading device makers are presently engaged in joint process development programs with Genus to develop low-cost manufacturing processes," said John Ogawa Borland, Genus' VP of strategic technology and inventor of the BILLI process. Genus worked with Sematech to prove the concept, and now it is being tested by such device makers as Hyundai Electronics, Philips Semiconductor, LG Semicon, Symbios Logic and Advanced Micro Devices.

"The process simplification advantages of BILLI extend to all memory and logic semiconductors," said Mr. Borland. "The additional benefit BILLI brings to logic IC design is that transistors can be placed closer together on a chip using bulk Cz silicon wafers and eliminating the need to use epitaxial wafers. Improvement in latch-up performance has been reported as high as a factor of 5x using the BILLI structure."

The Genus ion implant division in May moved into a new 70,000-square-foot manufacturing center in Newburyport, Mass.

Genus reported Symbios Logic has been able to implement a epi-free 0.5-micron CMOS logic process at its 200-millimeter (eight-inch) wafer fab in Colorado Springs, Colo., using a Genus MeV implanter, the BILLI structure and improved bulk Cz wafer denuding techniques.

"The Genus BILLI structure will enable us to deliver higher quality products to our customers," said Gayle Miller, director of advanced process development at Symbios Logic. "We are already seeing tighter process distributions and defect reductions due to the reductions in high-temperature processing requirements. Our ability to deliver product quickly is one of our primary focuses, and BILLI gives us an advantage in this area by minimizing process requirements."