二重回折格子による間隙変化に鈍感なマスクとウエハの位置合わせ法

概要

論文の詳細を見る
This paper presents an X-ray lithography alignment method insensitive to mask-wafer gap variation, using dual gratings. Diffraction light beam intensities for various dual gratings were calculated on the assumption that each grating is a sinusoidal amplitude grating. As a result, if dual gratings, consisting of a linear grating on the mask and a checkerboard grating on the wafer, are used as a alignment key, it was found that the diffraction beam intensity I (0,1), zero order in x (displacement) direction and first order in y direction, is independent from mask-wafer gap variation. The fact was confirmed by more detail calculations and experiments. Alignment experiments were carried out using intensity difference ΔI=I_1(0,1)-I_2(0,1) between two pairs of the dual gratings, which were arranged to have 180° phase shifted signal with reference to each other. A resolution better than 0.01 μm and 0.03 μm(3σ) alignment repeatability have been achieved among 25 μm and 55 μm gap variations.
公益社団法人精密工学会の論文
1988-10-05