A three‐dimensional resist shape simulator and its application to submicron VLSI process

Abstract

A three‐dimensional photoresist shape simulator has been developed for the submicron process. Using this simulator, it is possible to analyze and optimize the photoresist process using an arbitrary projector, photoresist, and developer. In this technique, considering the man‐machine interface, the three‐dimensional shape of the photoresist can be shown in a colorgraphic VDT and plotter. Comparing the result of the threedimensional simulation using the contact hole pattern with that of the two‐dimensional simulation, a discrepancy occurs in the dimension less than 1 μm between the two techniques, and it has been found that threedimensional simulation is necessary when the width and depth of the pattern are in the same order. Using the three‐dimensional simulation, a resolution of 0.5 μm cannot be achieved when the wavelength of the light source is 435.8 μm, the numerical aperture of the projection lens N.A. is 0.28, and the coherency s̀ is 0.7. However, such a resolution can be achieved by using the wavelength of the light source of 435.8 nm, N.A. of 0.42, and s̀ of 0.5.