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Technology Stocks : General Lithography -- Ignore unavailable to you. Want to Upgrade?

To: TI2, TechInvestorToo who wrote (867)	3/9/1998 8:47:00 AM
From: Volsi Mimir	Read Replies (1) \| Respond to of 1305

New short Article in Semiconductor Online about Lithography from my favorite writer Katherine Derbyshire: news.semiconductoronline.com INDUSTRY NEWS 03/05/1998 New I-Line Tools Match Critical, Non-Critical Layers. -------------------------------------------------------------------------------- With all the excitement about advanced lithography at last week's SPIE meeting, it's easy to forget that DUV (248 nm) lithography is only starting to ramp up to full production. I-line lithography is still very much alive. Moreover, the same fabs that use DUV for critical levels use i-line for the other layers of the device. By "mixing-and-matching" in this way, ASML product manager Bert Koek explained, users reduce costs by as much as 30 percent per non-critical layer (See Figure). In that context, it's easier to understand the recent announcements of new i-line steppers and step-and-scan tools (or "scanners") by all of the Big Three stepper vendors. ASML's new scanner [See I-Line Step & Scan in the Semiconductor Online Product Showcase] debuted at SPIE, Nikon announced a second-generation i-line scanner at SEMICON Japan, and Canon recently introduced a new i-line stepper. The three new systems serve as warning shots in an upcoming battle between steppers, which expose an entire die with a stationary lens then step to the next image field, and scanners, which scan the reticle through a small, well-corrected image field before stepping to the next location. According to Koek, interest in scanners began at the DUV level. They offer superior control over linewidth and overlay, while increasing the exposure field size. Scanners can also focus dynamically, following wafer topography more accurately. On the other hand, scanning the wafer and the reticle simultaneously with the necessary precision is a difficult engineering problem. Early scanner customers were worried about reliability, but felt that the superior image quality was worth the risk for critical levels. Now, Koek said, these reliability fears have mostly been overcome, and customers want to use scanners for both DUV and i-line in order to match field size between the two. Allan Dickinson, vice president of sales and marketing at Nikon Precision, disagrees. He notes that lithographers are facing simultaneous transitions to DUV excimer laser light sources, 300 mm wafers, and step-and-scan exposure tools. About half of Nikon's customers are buying DUV steppers to reduce the amount of technology change the fab must swallow at once, he told Semiconductor Online. Logic and ASIC fabs seem to find the scanner's larger field more compelling than DRAM vendors do, probably because logic die sizes tend to be larger. Even when fabs do use DUV scanners, Dickinson said, most are using i-line steppers to mix-and-match. Both Koek and Dickinson agreed that scanners are the wave of the future, though. Increasing field size and control of aberrations will eventually force users to switch over. The question is, when? By Katherine Derbyshire