Optical Lithography Strategy

Paul Rissman rissman at stanford.edu
Fri Oct 19 10:09:39 PDT 2007

Dear Labmembers:

As you know, acquisition of the ASML stepper has greatly improved the 
capability to do lithography at SNF.  We now have a factory 
reconditioned tool which is covered by a maintenance contract for at 
least the next 3 1/2 years.  ASML staff have been on site 3 days a 
week to support special applications.  In addition, some of the users 
have learned that they can save on mask costs, since 5" reticles can 
be fabricated on the Micronic and it is fairly straightforward to put 
multiple levels on one reticle.  For example, the six EE410 mask 
levels fit on three reticles.

Given this improvement, we have been able to migrate users off our 
older, less supportable tools, in particular the Ultratech and Nikon 
body 4.  Here is our plan for those tools in the future.

Ultratech:  For more than one year now, we have been discouraging 
users from starting new projects on that tool.  It is no longer 
supportable - we have limited maintenance help from either Ultratech 
or 3rd party companies.  Parts continue to be a problem, and we are 
starting to run out of those we have been able to cannibalize off the 
previously retired instrument.  Documentation and software for the 
system are non-existent.  Like a 22 year old car, the cost of 
maintaining this instrument far exceeds its usefulness.  Mahnaz, 
Mario and Gary will continue to support the few existing users 
through the end of this year, and then we will retire the 
stepper.  While I understand that this may be difficult for some 
users, we will do everything possible to ease your transition to the 
ASML or one of the contact printers.

Nikon body 4:  Regretably the story is not much different for the 
parts and service on the 20 year old instrument continues to be 
exceedingly difficult.  NPI has only limited interest or knowledge of 
servicing the stepper.  We have found 3rd party vendor that can 
supply parts, but has been reticent to service the tool.  Many of the 
parts on the system are wearing out.  For example, failures have 
occurred because small tygon pneumatic hoses are drying out and 
cracking.  Many of these are almost impossible to service without 
complete disassembly of the machine.  The system continues to limp 
along, but we strongly discourage users from starting new 
projects.  Hopefully we can define a retirement strategy for the Nikon in 2008.

Obviously, if we only have the ASML, even with a service contract, 
there is some risk.  However, there are many ASML instruments in the 
field, including at UC Berkeley and some of the other NNIN sites.  We 
know that we can match our system to the UC system since ironically 
supporting them was the first project on our stepper.  In the long 
term, we are hoping to secure an ASML 2500 generation system as backup.

We realize that these changes can be difficult and 
inconvenient.  However, in the long term, making the transition to a 
more reliable (and more capable) lithography tool will make your 
project go more quickly and enhance your results.  Please let me know 
if you have any questions or concerns.

Paul Rissman

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