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Politics : Formerly About Applied Materials -- Ignore unavailable to you. Want to Upgrade?

To: Duker who wrote (31308)	7/7/1999 5:43:00 PM
From: Proud_Infidel	Read Replies (1) \| Respond to of 70976

Equipment makers polish gear for copper processes By Craig Matsumoto EE Times (07/07/99, 4:23 p.m. EDT) SAN FRANCISCO — Capital-equipment makers will storm this year's Semicon West trade show with copper-related wares, many of them correcting or improving the addition of copper interconnects to a production process, which is only beginning to come to fruition. Copper has been a big topic at Semicon West for the past three years, but mostly for deposition front-runners Novellus Systems Inc. and Applied Materials Inc. More recently, the technology has advanced from being a single-minded Novellus obsession to a trend exploitable by more of the equipment industry. Front-runners such as IBM Corp. have reached production volumes with copper-interconnect chips. As a result, equipment makers beyond the wafer-deposition phase can start aiming at improving yields for copper manufacturing. Many early adopters are experiencing low yields in their first endeavors. Some of the kinks are to be expected with a new manufacturing process, but it's also true that copper metal is difficult to control. It contaminates silicon and aluminum readily, cutting in like a virus when given the opportunity. It also travels. Traces of it can be left on equipment "chucks" — the robot arms that carry the wafers — and could contaminate the next wafer in line. That's particularly true for some processes, where copper is sprayed around the edges and even onto the back, to ensure that enough of the wafer is exposed to the metal. If the excess is not properly washed off, copper remains to contaminate the rest of the fab. "So now you have copper in places that you don't want it. You have it on the ring exclusion zone [the area around a wafer's edge where no die are present], you have it on the edge of the wafer," said Michael West, business and strategic test director for SEZ America (Phoenix). SEZ has sold spin processing machines, used for wafer cleaning, since 1990, and at Semicon the company will show how it has adapted that technology to remove excess copper from wafers. Among the company's selling points is that its machines can clean the backs of wafers without touching the front. The company will unveil the product at Semicon along with data from early tests with Sematech. Another problem is that copper lines lie in deep trenches. Gaps or flaws at the bottom of a via can only be found through electron-beam inspection, according to officials of KLA-Tencor Corp. (San Jose, Calif.), whose eS20 e-beam inspector was announced July 1 and will be shown at Semicon. Scanning electron microscopes such as the one in the eS20 are available, but their operation is too slow for most fabs, said Robert Cappel, director of e-beam marketing for KLA-Tencor. The eS20 speeds up throughput, making e-beam inspection practical for semiconductor production. KLA-Tencor officials are suggesting that a combination of optical and e-beam inspection be used, combining the technologies' trade-offs of speed and precision, and the company plans to show off software that can optimize a fab's combination of the two. Even if deposition goes well, the performance boost of copper can be diluted if the initial barrier and seed layers — made of tantalum and a thin layer of copper, respectively — vary too much in thickness. That's a problem associated with physical vapor deposition (PVD), the method used by existing barrier and seed tools. Its effectiveness can be quite high but can never match chemical vapor deposition (CVD), which creates a finer-grained coverage of a particular trench. Genus Inc. has developed a copper CVD deposition tool called Lynx2, currently undergoing tests with "multiple customers," said Tom Seidel, Genus' chief technical officer. The technology, used for the barrier and seed layers, provides deposition that's more uniform and easier to control, Seidel said. Better control could be important because it eliminates the need for deposition on the edge and back of the wafer, erasing some of the contamination threats that companies like SEZ guard against. But for all its advantages, the CVD technology won't be going prime time just yet. "Most of our customers are looking at the 0.13- and 0.1-micron level, where the CVD-based technology is obviously more important," Seidel said, noting that "about half" of Genus' customers won't implement copper until after the 0.18-micron generation. Some companies claim they will stretch PVD to 0.13 micron levels, but Seidel is doubtful that can be done effectively. "The real battlefield here is whether CVD makes its entry at 0.13 or not," he said. eetimes.com