Study On Phase Grating Alignment Technology

With the development of lithography technology, alignment lithography systems with nanometer critical line-width dimension require higher alignment accuracy. In this thesis, the principal and feature of several phase grating alignment systems are introduced firstly; Alignment signal of phase grating alignment mark and the factors of influece of alignment signal are analysed secondly; This paper studies and compares three main factors which affect the diffractive error of alignment mark thirdly; At last, by buiding a formation model of calculating and analsing the asymmetric mark, the diffractive efficiency and alignment errors of the asymmetric mark are studied. The results of the paper are in accord with the datas of the emulator. In general, this study is significant. It offers a mark deformation model for studing the diffrative efficiency and alignment errors, which is feasible and helpful of improving alignment accuracy.