Optimum combination of source, mask, and filter for better lithographic performance

We have tried to find optimum combinations of source, mask and pupil filter suitable for all kinds of mask pattern with critical dimension (CD) of 0.18 micrometers by aerial image simulation. The annular aperture radii of deep UV source (wavelength 193 nm) are controlled to give optimum annular illumination for equal line/space pattern. The optimized illumination aperture has inner radius of (sigma) in equals 0.525 and outer radius of (sigma) out equals 0.600. Under this illumination, various transmittances of halftone mask are investigated as mask variation and phase distribution of pupil filter is modulated annularly. The aerial image characteristics are compared among eight combinations of illumination, mask, and filter in order to find the most effective combination for each typical mask pattern such as equal line/space, isolated line, isolated space and contact hole. The effective method is annular illumination for line/space, pupil filter for the other patterns. The combination of annular illumination + binary intensity mask + pupil filter is recommended for simultaneous printing of all kinds of pattern.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.