LSI, Micron to embed DRAM ASICs

Electronic News, June 9, 1997 by Crista Hardie Souza, Peter Brown

Mountain View, Calif.--The emerging embedded DRAM ASIC market received another boost last week as two major agreements were signed by heavyweight semiconductor manufacturers. The two agreements cap a booming 10-month period, during which virtually every major ASIC house has announced its proprietary plans to bond DRAM with logic.

U.S. ASIC leader LSI Logic and DRAM manufacturer Micron Technology inked an agreement to develop and produce digital logic ICs that will have the capability of embedding between 64 and 128 megabits of DRAM on a single ASIC--ending speculation as to when LSI would reveal its plans for this hot technology. In addition, teaming up for a second time, Toshiba and Chartered Semiconductor Manufacturing announced a partnership to manufacture embedded DRAMs in Singapore. The companies worked together in 1994 to develop a generic 0.5-micron CMOS process, which Chartered has employed in its foundry fabs (EN, Nov. 7, 1994).

Under the new agreement, Toshiba will license Chartered its embedded DRAM process from 0.35 down to 0.25-micron, allowing Chartered to offer a whole new capability to any of its list of foundry customers. "When the embedded DRAM demand comes along we wanted to be in a position to support our customers, and we think we're looking at about 1998-99," commented Tan Bok Seng, president and CEO of Chartered.

The companies are not disclosing financial details; however, the deal is described as a five-year agreement that calls for a technology exchange and provides Toshiba with a significant amount of foundry space at Chartered's Fab 3.

The embedded DRAM devices will be manufactured using a trench-capacitor technology, which Toshiba currently uses in its 16-megabit and 64M DRAM parts. The trench-capacitor is said by Toshiba to be a more reliable and efficient process than the stack structure common for other embedded applications.

Separate Marketing

Under the terms of the LSI/Micron agreement, each company will develop and market the DRAM ASICs separately without royalties being involved in the process, said Simon Dolan, VP of strategic marketing for LSI Logic. Micron will also have access to portions of LSI's CoreWare library. However, Mr. Dolan would not disclose the details of what portions would be available to the memory company.

Also, the devices will not be manufactured in one central location. Micron will handle the DRAM layers and then will ship the wafers to LSI, who will then implement the logic layers, Mr. Dolan said. LSI and Micron said this division of labor won't set back productivity or increase the risk of contamination because of past agreements that both companies have had, with similar terms to manufacture the wafers in two separate locations. LSI and Micron plan to have products by mid-1998.

Graphics controllers are talked about as the number one application for embedded DRAM, using 1 or 2 megabytes of memory--equivalent to 16 megabits of DRAM, which is the sweet spot right now on the memory curve, according to observers.

Typically, applications where there is a big performance concern in terms of bandwidth of the memory, as in portable or battery-powered devices, digital video cameras or DVD, are veering toward embedded DRAM. Combining the memory and logic on the same chip speeds up the processing power, because the controller no longer has to go off-chip and onto a bus to access system memory. Hard disk drives, set-top boxes and HDTV are also eyed as potential consumers of the integrated devices.

Although in recent months the embedded DRAM market has experienced tremendous popularity among the ASIC vendors, mixing the DRAM and logic worlds is no simple task, said Gene Cloud, VP of marketing for Micron Technology. "The challenge is to combine very fast transistor characteristics and high-capacitance requirements in a single, unified process and then add five layers of metal without driving cost up dramatically," he said.

Process Barrier

However, a handful of Japanese memory and logic companies, notably NEC, Fujitsu, Toshiba, Hitachi and Mitsubishi Electric, have already overcome the process barriers, according to Ray Hawkins, senior VP of worldwide sales and marketing for Chartered Semiconductor Manufacturing, a Singapore-based foundry which just announced an embedded DRAM partnership with Toshiba.

"The barrier for foundries is the time required for starting from having nothing to having a manufacturable production-worthy process. Our agreement with Toshiba just eliminates that time for us, because we're just going to port that whole technology into us," Mr. Hawkins said. The process is expected to be ready when Chartered's Fab 3 comes on-stream later this year.

Morry Marshall, senior analyst at In-Stat, a market research firm based in Scottsdale, Ariz., said the technology is broken down into two groups: Those companies that have the DRAM process and those companies that have the ASIC and intellectual property. Combining the two is extremely difficult alone, he said, and twice as challenging when two separate companies are attempting to roll out a proven product. However, it has been done in the past, and with the progress in technology, anything is possible, he added.