LONDON STMicroelectronics and Taiwan Semiconductor Manufacturing Co. (TSMC) are each ready to move their respective silicon germanium (SiGe) process technology into volume production.
By bolting SiGe onto an established process, ST reckons it can build faster, lower-noise RF circuits more cheaply than companies with dedicated and SiGe processes. ST is using non-selective epitaxy to put SiGe onto chips made on its 0.35-micron BiCMOS process, said Jean-Pierre Aubert, RF business development manager for ST.
The company in the future will move with finer-geometry processes to a selective epitaxy, where SiGe is deposited only onto parts of a device.
"We don't see a performance difference between selective and non-selective, but we are looking at selective for new developments," said Aubert.
TSMC is planning a similar road map, kicking off with a blanket SiGe process then moving to a selective version for 0.18-micron technology, a company spokesman said. "When 0.18 micron goes online, it will have TSMC's vanilla logic. It is intended for circuits like fast mixers," he said.
The process is expected to come onstream in September 2002.
As it targets analog and RF chip production, TSMC is lining up a portfolio of design kits and intellectual property (IP) libraries for its SiGe processes. It has signed up IP suppliers such as Antrim Design Systems, Barcelona Design and NeoLinear for its CMOS analog process.
"We are developing the models for SiGe," said Nelson Seiden, vice president of marketing for Antrim (Scotts Valley, Calif.). "It is the next thing we will move into."
ST prefers non-selective epitaxy, Aubert said, because "we are focusing on cost and reliability. We don't see a specific price increase linked to the use of SiGe. For us, the cost is mainly linked to volume."
Aubert said that the base 0.35-micron process on which ST's SiGe module is being deployed is already running in volume across a number of the company's fabrication facilities.
"Low-cost SiGe can be used for low-end phones. Its main benefit is in LNA low-noise amplifier integration," said Aubert. "At close to 2 GHz, it is very challenging to build dual-band LNAs in BiCMOS. SiGe can deliver a two-times improvement in power consumption and improved noise figures."
ST is looking at more advanced processes such as carbon-based SiGe, Aubert said. "At the moment, it is at the R&D stage," he said. The company has been encouraged to look at carbon additions by the research performed by Motorola Inc.'s semiconductor division, he said.
Chris Edwards is the editor of Electronics Times, EE Times' sister publication in the United Kingdom.