Motorola does 'me too' on copper; LSI in wings

Electronic News, Oct 13, 1997 by Chad Fasca

Austin, Texas--Not to be outdone by its PowerPC chip-making counterpart, Motorola publicly disclosed that it has developed a new IC process incorporating copper interconnects to replace aluminum wiring. LSI Logic also told Electronic New that it has copper capability, though its plans differ from those of IBM and Motorola.

The news came one week after IBM reported its own advances in copper technology. That news sent IBM's shares up 4.6 percent. Motorola's announcement confirmed speculation that the company had its own copper process technology. Industry insiders believe Intel has the technology as well, although the company has publicly stated that aluminum will carry them into the next century, roughly down to 0.13-micron.

Called a dual-inlaid metallization technique, Motorola's copper process takes advantage of copper's inherent higher conductivity than aluminum, which allows for smaller, thinner interconnects as well as its greater resistance to electro-migration. This makes possible smaller, faster ICs with greater reliability. The program had been in development at Motorola for the past two and one half years in their R&D laboratories.

Actually, Motorola has been involved in low-key copper research for close to 10 years. "We did for about seven or eight years, we had a really low-level program. We really got focused two-and-a-half years ago, and then went all out. The two and a half-years just marks when we fully began to budget people and the money (for the program)," said Fabio Pintchovski, director of the advanced product research and development laboratory at Motorola.

The Motorola process incorporates six layers of planarized copper interconnects in a 0.20-micron CMOS logic technology capable of high performance, using a 1.8V supply voltage. Effective channel lengths are estimated in the 0.15-micron range or lower. Samples of the first product using the copper interconnect technology are scheduled for introduction in the summer of 1998 with production ramp planned in September 1998.

"We are putting it into the microprocessors and static memory next year. Those are the drivers, the ones (that can use copper) right away," said Mr. Pintchovski. This will spread out over the whole of Motorola's high- performance devices including telephones, pagers and DSPs in the next two to three years.

Like IBM and many industry members, Motorola has seen the future written in copper. It just took some time to iron out some of the kinks in the process.

"Copper has been a good material for a very long time and the question that I have been asked is, "What have you been waiting for?' "

As it turns out, Motorola and others were waiting for the right material to encapsulate copper so that it would not diffuse throughout the silicon. Another problem closely associated with the diffusion problem is contamination of the fab facility and tools. According to Mr. Pintchovski, Motorola has solved this long held fear. He says Motorola has a production line that can run both material that has copper and does not, meaning standard platinum, provided they maintain a set of rules. "Some areas you can make and run together, some you can't. So, basically you develop a series of regulations," said Mr. Pintchovski.

A limited number of tools, such as CMP, have to dedicate to copper, "but that is a pretty small number in reality, it turns out," he said. Still, relatively few exclusive tools or not, the copper process does lead to higher capitalization requirements. But, Motorola rationalizes these by the performance in production benefits that copper returns. The benefit is that the copper process actually eliminates a number of steps associated with metalizing aluminum. Just as IBM, Motorola boasts capability for six layers of copper. With each layer, Mr. Pintchovski points out, Motorola is multiplying its cost savings.

"Even though you have to capitalize more, it will pay for itself by a shorter process, especially when you have six levels of copper...you multiply the number of steps that you are saving so that (the savings) can be significant," said Mr. Pintchovski.

Motorola will describe further technical details of the process at the International Electronic Devices Meeting (IEDM) in December. But the company was slow to announce its copper technology in the first place, something that IBM capitalized on.

"Motorola is well-known as a communications company; we announce a lot of our products, cell phones, pagers, but not base technology--you don't really see a lot of announcements on our technology. (Process announcements are) mostly brought up through technical conferences. So, the vehicle we have used for bringing out this technology has been different, or at least has been this way," said Mr. Pintchovski, who admitted that things are changing, in part influenced by the recent bonanza surrounding IBM's announcement. He did not discuss any details as to how things are changing in Motorola's publicity strategy. "We are learning," he said.

LSI Logic is learning, too. They say they have the technology necessary for copper production. They also say that the company has focused its news efforts on products over process announcements.