To: FJB who wrote (1447 ) 3/6/1998 2:26:00 PM From: Tulvio Durand Read Replies (1) | Respond to
Thanks Bob and Ian for all the information on SVG's technology. I now better understand SVG's step and scan technology.
My take (for what it's worth) is that, compared to its competitors, SVG does have a unique and truly superior catadioptric projection system leading to better sharpness, accuracy, while at the same time allowing more energy to reach the wafer for quicker exposure. Some of its other claims (largest field, micro-scan via step and scan, etc.) may have been true at one time, but may no longer be true now because the competition has caught up.
Its biggest competitive edge was during the time with Micrascan-2+ when this was the only machine in the world capable of sub-0.25 features printing and with reasonably fast throughput using the Hg-Xe lamp. Its competitors were at a significant disadvantage because their all-lens projection systems were not as sharp nor as fast and lost much of the DUV energy from the Hg-Xe lamp in heating up the long train of lenses.
Much of the Micrascan-2+ advantage was lost with the advent of Cymer's DUV excimer laser because it allowed the competitors to project the narrow-beam DUV though their all-lens projection systems and still have enough DUV energy left over with which to print wafers at reasonably fast throughput. The competitors' new step-and-scan tools now offer comparable print field-area, and comparable wafer throughput.
But the DUV-laser equipped Micrascan-3 still remains the more efficient and more accurate tool because of its superior catadioptric projector design. Its principal advantage over the competition is that it allows more accurate registration of superposable DUV/i-line fields which is needed for today's mix-and-match wafer printing. ASM has recently announced a new step-and-scan i-line tool that supposedly achieves comparable field-registration accuracy required for DUV/i-line mix-and-match.
The relevant remaing question in my mind are:
1. Whose step-and-scan tool gives better mix-and-match throughput and smaller achievable critical dimensions for the $ investment?
2. Which vendor is better able to produce tools per the required chipmakers' need dates?
3. Which vendor is better able to support the tools for maximum availability?
Based on sales volume I believed ASM to be the vendor of choice, and am invested in it. I would consider investing in SVG if I had the answers to those three questions. BTW, as you probably know, I'm invested significantly in Cymer.
Regards,
Tulvio
