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<Both e-beam and laser systems are capable of producing PSMs. E-beam systems have inherently higher resolution, laser systems are inherently faster, so there's a tradeoff between the two for any particular mask>
If dry etch is required ( attenuated type and the quartz etch of Marc's type), the current optical resists used by the laser tools have an advantage over current ebeam resists. Dry etchable ebeam resists are currently being introduced. In strong shifter types with high resolution requirements ( out rigger, certain opc etc), a mix and match with ebeam to define chrome image and laser tool to define quartz etch is used. These quartz etches can require multiple exposures to reduce defects and/or effect of defects. If the chrome is used as a self aligned "mask" to define etch, then the second level exposures can be simple exposures used on older generation tools.
<To my knowledge, PSMs are not yet being used in production applications.>
Check SPIE 1996 AMD paper by Ackman/Nistler/Spence et al. They showed production results with I line
<Current production technology (0.25 micron features) is pretty close to the exposure wavelength (248 nm), so the resolution enhancements needed are relatively minor.>
Yes, and I line with PSM accomplished it earlier just as next results can be accomplished with current exposure tools ( Grant's work etc) as you have published..
<A PSM is a two-level mask, so using PSMs is a pretty radical step that chip makers won't take until they have to>
I agree and they are at least 2 level masks. I believe that we are having a paradigm shift in lithography that pilot production will be using these psm and other tricks to meet time to market requirements. As new wavelengths, and requisite infrastructure, become available then volume production will adopt the new wavelength as a more cost effective approach. This of course is a more expensive approach and requires more infrastructure. The implication is that the big players become bigger and the weak become weaker. If you have captive capability, its not radical or expensive and you don't need to talk about. Time to market means market share and better margins.
Thanks for all your great posts, I really am grateful for them.
TI2
PS- Can you get Marc to come here? Now thats a legendary character, Art is merely infamous. |
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