Using advanced simulation to aid microlithography development

A memory and computation efficient three-dimensional simulation system for the UV lithography of thick SU-8 photoresists

“…where I s is the original intensity of the incident UV light, 1 R , 2 R and 3 R are the reflection coefficients at air/index matching materials, index matching materials/SU-8 and SU-8/substrate interfaces, respectively, c(u) and s(u) are the 2,3,4) and v i (i=1,2,3,4) represent the Fresnel numbers in x-direction and y-direction, respectively. λ 1 denotes the wavelength of incident 365nm-UV light in the air medium, and z is the vertical distance from the mask plane to the calculation point in photoresist.…”

“…Simulation tools are ideally suited for the optimization of the complicated lithography process of thick photoresists. Although some simulation software for the thin photoresist lithography process has been commercialized [4], the lithography process of thick photoresists, such as thick SU-8, can not be accurately implemented by the software specified for the thin photoresists, since the thick SU-8 has properties different from the thin photoresists. During the passing years, some simulation approaches for lithography of thick photoresists have been presented [5][6][7][8], however, the application of three dimensional simulation tools for thick photoresist lithography is currently significantly limited, because of the disadvantages of main-stream algorithms used.…”

Numerical simulation of partially coherent broadband optical imaging using the finite-difference time-domain method

“…Rigorous numerical electromagnetic methods are gaining more attention for characterizing, optimizing and synthesizing optical systems in several areas of physics and engineering, including photolithography [1], IC inspection [2] and biophotonics [3]. One of the most popular of these methods is the finite-difference time-domain (FDTD) method [4], which provides a direct time-domain solution to Maxwell’s equations by discretizing the electromagnetic field both in space and time.…”

Numerical study on photoresist etching processes based on a cellular automata model

“…At the same time, 3-D optical lithography simulation becomes significantly important for the accurate analysis of complex structures, such as contacts, corners, etc., and for the optimization of the masks for these structures, as the complexity of integrated circuits (IC) increases [1] . Furthermore, simulation is essential to determine the best way of pushing the present set of equipment involved in optical lithography to its maximum limits [2] .The photoresist etching simulation is usually the most time-consuming step among the basic optical lithography simulation steps [3] , so the key to increase the speed of optical lithography simulation is to speed up the simulation of the photoresist etching process. During the past two decades, some simulators for optical lithography processes have been successfully developed…”

“…At the same time, 3-D optical lithography simulation becomes significantly important for the accurate analysis of complex structures, such as contacts, corners, etc., and for the optimization of the masks for these structures, as the complexity of integrated circuits (IC) increases [1] . Furthermore, simulation is essential to determine the best way of pushing the present set of equipment involved in optical lithography to its maximum limits [2] .…”