Kenny K. H. Toh

EECS Department
University of California, Berkeley
Technical Report No. UCB/ERL M90/123
December 1990

http://www2.eecs.berkeley.edu/Pubs/TechRpts/1990/ERL-90-123.pdf

A Three-Dimensional Optical Lithography Simulator has been developed based on a new ray-string algorithm for dissolution etch-front advancement. In developing the new algorithm, performance studies of cell, string and ray algorithms were carried out in two dimensions. A key finding was that a recursive ray method for the calculation of the surface advancement vector produced numerically stable and highly accurate results. The optimum algorithm was found to be one that combines the recursive-ray method with the string approach, in which etch-rate-dependent rays are used to advance the nodes, segments and triangles which make up the etching boundary. This algorithm has been implemented in 3D in the C programming language, using a linked-list data structure to represent the etching boundary mesh. Recursive time-step selection, mesh modification, and clipping and delooping of the etch boundary surface have been implemented.

The 3D ray-string etch simulator has been coupled to 2D imaging and 3D resist-exposure simulators to form SAMPLE-3D, a complete fast and accurate 3D photolithography simulator. The complete simulator has been used to investigate the correlation between the 2D aerial image and the 3D developed resist profile. This includes applications to the printability of defects where the nonvertical resist dissolution effects play a strong role, as well as the design of phase-shifted masks where phase-transitions tend to print.

Advisor: Andrew R. Neureuther

BibTeX citation:

@phdthesis{Toh:M90/123,
    Author = {Toh, Kenny K. H.},
    Title = {Algorithms for Three-Dimensional Simulation of Photoresist Development},
    School = {EECS Department, University of California, Berkeley},
    Year = {1990},
    Month = {Dec},
    URL = {http://www2.eecs.berkeley.edu/Pubs/TechRpts/1990/1670.html},
    Number = {UCB/ERL M90/123},
    Abstract = {A Three-Dimensional Optical Lithography Simulator has been developed
based on a new ray-string algorithm for dissolution etch-front
advancement. In developing the new algorithm, performance studies of
cell, string and ray algorithms were carried out in two dimensions. A
key finding was that a recursive ray method for the calculation
of the surface advancement vector produced numerically stable and
highly accurate results. The optimum algorithm was found to be one
that combines the recursive-ray method with the string approach,
in which etch-rate-dependent rays are used to advance the nodes,
segments and triangles which make up the etching boundary. This
algorithm has been implemented in 3D in the C programming language,
using a linked-list data structure to represent the etching boundary
mesh. Recursive time-step selection, mesh modification, and clipping
and delooping of the etch boundary surface have been implemented.

The 3D ray-string etch simulator has been coupled to 2D imaging and
3D resist-exposure simulators to form SAMPLE-3D, a complete fast and
accurate 3D photolithography simulator. The complete simulator has
been used to investigate the correlation between the 2D aerial image
and the 3D developed resist profile. This includes applications to
the printability of defects where the nonvertical resist dissolution
effects play a strong role, as well as the design of phase-shifted
masks where phase-transitions tend to print.}
}

EndNote citation:

%0 Thesis
%A Toh, Kenny K. H.
%T Algorithms for Three-Dimensional Simulation of Photoresist Development
%I EECS Department, University of California, Berkeley
%D 1990
%@ UCB/ERL M90/123
%U http://www2.eecs.berkeley.edu/Pubs/TechRpts/1990/1670.html
%F Toh:M90/123