Chip Makers Shocked By Copper Costs

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July 24, 1998 (8:47 AM EDT)

SAN FRANCISCO -- Lucent is among the growing list of semiconductor makers considering how rapidly to use copper-interconnect materials on high-speed digital integrated circuits. While Lucent will inevitably turn to copper, it doesn't see the technology as cost-effective for the next generation of circuits, said Emelio Martinez, who heads interconnect research at Lucent's Bell Laboratories.

Martinez' disclosure came on the heels of dazzling introductions at the annual Semicon exhibition here in San Francisco, where expensive new equipment for copper took center stage. The price tags caught many by surprise.

"Some manufacturers are bound to feel sticker shock," said Allen Harris, vice president and chief technology officer of Novellus Systems, in San Jose, Calif.

Novellus made waves with Damascus, a front-to-back vapor-deposition system whose centerpiece is an electrofill (electroplating) system for copper interconnects. Another Novellus introduction, the Sabre electroplating system, is one of the chip industry's only manufacturing systems for copper interconnects. But its $3 million-plus price tag left Lucent and others gasping.

"That cost was not foreseen," said Martinez.

In addition to electroplating equipment, copper-interconnect manufacturing will require an $8 million to $10 million investments in chemical vapor deposition (CVD) and physical vapor deposition (PVD) equipment, plus additional outlays for dielectric etching and chemical-mechanical polishing equipment. Steppers and metrology equipment will add to the bill.

Against those costs, Harris said because copper via plugs are easier to implement than aluminum, the number of metallization layers on a complex circuit can be reduced. The overall cost of copper interconnects, he said he believes, is 30 percent less than circuits with aluminum deposition and etching.

Novellus' stated marketing strategy is to be first to offer a front-to-back manufacturing solution for copper, and to sell as many as it can before competitive offerings appear. Despite the downturn in the semiconductor industry and the curtailment of capital-equipment investments, Harris said many of his customers are excited about the move to copper.

"Everyone agrees there is a deep crisis in the industry -- a lack of capital -- but that provokes a sharper focus on new technology," he said.

Few Novellus customers are following IBM's lead in using copper at 0.22 micron, but many, Harris said, are planning an implementation at 0.18 micron. "The copper timing was really excellent," he said. "The use of copper interconnects will grow 80 percent per year for the next several years."

"People get euphoric about new technologies like copper until they look closely at the costs" said Ashok Sinha, president of the metal-deposition-products business group at Applied Materials, in Santa Clara, Calif., Novellus' chief competitor. "The cost [of implementation] is more than dollars and cents. If people put $3 million into, say, electroplating equipment, do they get $30 million in value from their new chips?"

'People get euphoric about new technologies like copper until they look closely at the costs.'
-- Ashok Sinha
Applied Materials

The answer may not always be yes, Sinha said. If the goal is to clock processors and logic at 500 MHz, that could be done with 0.18-micron CMOS using today's aluminum interconnects and low-K dielectrics.

With a substantial installed base in aluminum metal-deposition equipment, Applied Materials is more interested in helping customers "migrate" to copper than in encouraging them to make a "grand leap."

Applied's Semicon introductions consisted of add-ons to aid copper-interconnect development, not a front-to-back manufacturing system. For example, the Endura Electra Cu system, introduced last year, implants barrier and copper-seed layers (in tantalum and tantalum nitride) for copper interconnects. Although Applied announced a "reactive pre-cleaning" system for copper interconnects last week, its copper electroplating and dry-fill CVD and PVD systems are still in a prototype stage.

Sinha said copper interconnects become significant where manufacturers need to clock their systems at 1 GHz or higher, and the driver may not be computers but advanced communications applications. The use of copper may begin at 0.18-micron CMOS, he said, but the transition will kick into high gear with 0.15- and 0.13-micron manufacturing.

"We're looking at a couple of generations until copper becomes even partially mainstream," said Sinha.

Martinez' Bell Labs team, meanwhile, will concentrate on low-k dielectric materials such as fluoride-doped silicon dioxide as the primary means of extracting higher speed from 0.18-micron CMOS. Citing five years of research in copper interconnects, plus partnerships with NEC and Sematech, Martinez said an ultimate move to copper is "a no-brainer. The problem is, when will it be cost-effective?"

Indeed, that's the question the whole industry is grappling with, said Mark FitzGerald, semiconductor industry analyst at Merrill Lynch, in San Francisco. "This will be a big market for 2000 or after," he said.

FitzGerald said he believes Intel will embrace copper at 0.13-micron geometries, but Advanced Micro Devices will be more aggressive in hopes of gaining a competitive edge. Indeed, AMD announced a partnership with Motorola this week, in part to gain access to copper technology.

An AMD spokesman confirmed that copper would come online in 2000 in AMD's K7 processor family, to be manufactured at 0.18 micron in a "megafab" under construction in Dresden. The spokesman confirmed that the Sunnyvale, Calif., company had taken delivery on "copper-capable" equipment from Applied Materials (an ion-metal plasma unit for barrier and seed layers), but declined comment on how AMD would amortize its costs.

A complete copper IC fabrication unit for demonstration purposes, Sinha said he estimated, would cost between $15 million and $20 million. Several such units, along with wafer-handling and clean-room equipment, would be required in a manufacturing environment.