Shot Leveling and Focusing with Interferometry for Optical Lithography of Sub-Half-Micron LSI

概要

論文の詳細を見る
This paper presents a shot-by-shot leveling applied to an i-line stepper system. This shot leveler utilizes laser interferometry with a laser beam that has S-polarization and a large incident angle to the exposure surface of the LSI wafer. Thereby leveling and focusing accuracy is preserved regardless of the wafer surface condition under the photoresist. This system acquires interference fringe data with charge-coupled device (CCD) line image detector, and extracts the fringe frequency and phase information with a fast-Fourier-transformation (FFT). These correspond to the tilt and height information of the photoresist surface. The performance was evaluated with 4M-DRAM process wafers. Tilt and height measurement linearity was proved to be ±2 μrad and ±0.3 μm respectively, and total leveling control accuracy was proved to be better than ±7 μrad.
社団法人応用物理学会の論文
1993-12-30