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Process Window Studies
Weir PW & LithoWorks PW |
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Analysis of Focus - SPIE (2002) |
Discusses the use of Phase Grating Metrology (PGM)
reticles and Phase Shift (PSFM) patterns to analyze
lithographic scanner performance. |
|
Study of the influence of substrate topography
on the focusing performance of advanced lithography scanners - SPIE
5040-47 (2003) |
Weir PSFM software is used to model and analyze focus
variations encountered in lithography. Special etched structures in
the wafer illustrate the ability of the PSFM/PGM reticle and Weir to
measure small focus steps. |
|
Critical evaluation of focus analysis methods
- SPIE 5377 (2004) |
Line-end-shortening (LES), ASML FOCAL, PSFM and PGM focus analysis
techniques are analyzed and compared in performance.
Scanner
lens-slit and reticle-scan signatures are derived by each and
compared against Zernike coefficients for the same lens. Scanner
induced systematic distortions of these signatures are shown and
modeled as a function of wafer location and reticle scan direction. |
|
Flight of the Scanner Slit (MLW 2004) |
The PSFM
reticle is used to analyze the flight-path of the reticle stage
during exposure. The stage is show to pitch, roll, bank and tilt
similar to an airfoil in flight. Analyses show a sensitivity of
focus errors to the scan direction and residual acceleration at the
start/stop of scan. |
