HSINCHU, Taiwan -- With chip processes pushing deeper into submicron technology, silicon foundries are wrestling with the escalating costs of producing prototype wafers and low-volume ICs. Several major pure-play foundries are now seeing growth in multi-project wafers (MPW), which are able to cut costs by packing four or five different chip designs on a single 8-inch substrate.
Taiwan Semiconductor Manufacturing Co. Ltd. here is also exploring the use of electron-beam direct-write technology to eliminate the use of expensive sub-wavelength photomasks, which are necessary to print device feature sizes smaller than the wavelength of exposure light. TSMC is working with tools from several suppliers, including Hitachi and Toshiba, to potentially apply e-beam direct write to low-volume wafer runs, but the prospects and timing of its use is "too early to predict," said Rick Tsai, executive vice president of operations.
Photomask sets for 0.15-micron ICs are now costing an average of $200,000, according to Ronald Norris, senior vice president of sales and marketing at TSMC. A recent survey of TSMC foundry customers showed 25% of design tape-outs being used to produce 10 wafers or less, Norris said.
With more reticles using advanced phase-shifting technology and optical proximity correction (OPC), mask sets could soon cost well over $400,000 for 0.13-micron technology. Some analysts have estimated that $1 million mask sets are not inconceivable in the future.
"We believe e-beam direct-write might be a way to handle these low-volume, leading-edge wafer runs," Norris said.
Another approach that is catching on with low-volume foundry customers is multi-project wafers, which TSMC is now offering for 0.25 and below processes. Last year, TSMC' ran about 30 MPW lots. In 2000, that number will more than double to about 70, according to Norris.
In Singapore, Chartered Semiconductor Manufacturing Pte. Ltd. is also seeing steady growth in multi-project wafers, said Rob Baxter, senior vice president of business operations. Last year, Chartered was running one or two MPW lots per quarter, but now the foundry company is launching at least one multi-project wafer lot every month for 0.18-micron processes.
"Some customers were not really keen on the idea at first but once they have seen the costs, the approach has become more popular. They are jumping on the bandwagon" Baxter added.
"There is definitely a cost barrier for some of the smaller volume products in moving into the advanced technologies," he said. "Some of the prototype wafers will be multi-project wafers, but when they go into volume runs, they customers will buy the whole reticle when they go to