포토레지스트 모델 파라미터 측정 및 현상 공정 후 포토레지스트 형상 시뮬레이션에 관한 연구

Abstract

A Study on the Measurement of Photoresist Model Parameters and Simulation of Developed Photoresist Profile Seungtae Park Advisor : Prof. Jong-Rak Park, Ph.D. Department of Photonic Engineering Graduate School of Chosun University In this paper, the characteristics of a photoresist were measured using the Dill model for the exposure process and the Mack model for the development process. Parameters A and B of the Dill model were directly determined using the absorption coefficients measured from unexposed and sufficiently exposed photoresist samples. The last parameter, C, of the Dill model was indirectly determined by analyzing the error between the theoretically calculated and experimentally measured transmittance for various exposure values. The Rmin and Rmax parameters of the Mack model were directly determined based on the measured dissolution rates using unexposed and sufficiently exposed photoresist samples. The remaining parameters, a and n, of the Mack model were indirectly determined by analyzing the error between the theoretically calculated and experimentally measured photoresist thickness variation for various exposure values with development time. Essentially the same analysis method was applied to the reduced Mack model using only parameter n, revealing that the original model employing parameters a and n exhibited smaller errors compared to the reduced model. Simulation of the photoresist profile after the development process was conducted using the ray tracing method. Measured pixel images were utilized for aerial image calculations in the simulation. Simulations for sawtooth patterns with various pitches(ranging from 21 μm to 210 μm) were performed and compared with experimental results, showing that as the pitch of the sawtooth pattern decreased, the height of the photoresist profile also decreased. The simulation results using the measured pixel image for the best focus condition were found to be in good agreement with the experimentally measured ones. Based on the simulation methodology summarized in this paper and the measured characteristic parameters of the photoresist, further research on optical proximity effect correction (OPC) will be conducted as a follow-up study.