Simulation of Optically Formed Image Profiles in Positive Photoresist

Michael Marson O'Toole

EECS Department
University of California, Berkeley
Technical Report No. UCB/ERL M79/42
June 1979

http://www2.eecs.berkeley.edu/Pubs/TechRpts/1979/ERL-m-79-42.pdf

A program to perform computer simulation of an optical projection printer was written in order to address the problems associated with replicating small lines in positive photoresist. The optical section of the simulation calculates the image intensity due to a mask pattern of periodic lines and spaces. The simulation considers the numerical aperture of the objective lens, multiple wavelength imaging, the presence of focus error, and partially coherent illumination of the mask. A novel algorithm for imaging with partially coherent light, relying heavily on intuitive insight, is presented in detail. A set of routines for the exposure and development of positive photoresist has been adapted and modified for the simulation. The final output of the simulation is a two-dimensional line-edge profile in resist.

The shape and position of the line-edge profile vary significantly with process parameters. Partially coherent mask illumination, an important parameter in projection printing, affects both the image intensity incident on the resist and the resulting developed profiles in the resist. Simulations show a reduced sensitivity of resist linewidth to exposure variation and an increased tolerance of the linewidth to focus error with partially coherent illumination.

Advisor: Andrew R. Neureuther

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BibTeX citation:

@phdthesis{O'Toole:M79/42,
    Author = {O'Toole, Michael Marson},
    Title = {Simulation of Optically Formed Image Profiles in Positive Photoresist},
    School = {EECS Department, University of California, Berkeley},
    Year = {1979},
    Month = {Jun},
    URL = {http://www2.eecs.berkeley.edu/Pubs/TechRpts/1979/9608.html},
    Number = {UCB/ERL M79/42},
    Abstract = {A program to perform computer simulation of an optical projection
printer was written in order to address the problems
associated with replicating small lines in positive photoresist.
The optical section of the simulation calculates the image intensity
due to a mask pattern of periodic lines and spaces.  The simulation
considers the numerical aperture of the objective lens, multiple
wavelength imaging, the presence of focus error, and partially
coherent illumination of the mask.  A novel algorithm for imaging
with partially coherent light, relying heavily on intuitive insight,
is presented in detail.  A set of routines for the exposure and
development of positive photoresist has been adapted and modified
for the simulation.  The final output of the simulation is a
two-dimensional line-edge profile in resist.

The shape and position of the line-edge profile vary significantly
with process parameters.  Partially coherent mask illumination,
an important parameter in projection printing, affects both the
image intensity incident on the resist and the resulting developed
profiles in the resist.  Simulations show a reduced sensitivity of
resist linewidth to exposure variation and an increased tolerance
of the linewidth to focus error with partially coherent illumination.}
}

EndNote citation:

%0 Thesis
%A O'Toole, Michael Marson
%T Simulation of Optically Formed Image Profiles in Positive Photoresist
%I EECS Department, University of California, Berkeley
%D 1979
%@ UCB/ERL M79/42
%U http://www2.eecs.berkeley.edu/Pubs/TechRpts/1979/9608.html
%F O'Toole:M79/42