BACKGROUND: Resist models for full-chip lithography simulation demand a difficult compromise
between predictive accuracy and numerical speed.
METHODS: Using a Gaussian approximation to the shape of the image-in-resist in the region of
development near a feature edge, the integral normally solved numerically in the Lumped Parameter Model
(LPM) can be evaluated analytically. As a result, a well known three-dimensional resist model (the LPM)
can be used in only two-dimensions (the Gaussian LPM), greatly improving speed without significant loss of
RESULTS: For a positive resist, the image in the region of soluble resist material can be well approximated
by a Gaussian image for all the mask features investigated.
CONCLUSIONS: The Gaussian LPM is expected to have accuracy similar to the LPM but with
substantially greater speed.