Vector analysis of two-dimensional Ronchi grating in the metrology system

摘要

The semiconductor industry is aggressively pushed to produce smaller and smaller feature size from their existing base of lithography system, wavefront aberration should be derived by comparing ideal and real wavefronts at the wafer plane of a high resolution lithography system. In modern optical metrology, shearing interferometer is used more and more widely. We proposed a two-dimensional shearing interferometer, using two-dimensional Ronchi grating instead of a traditional one-dimensional grating, which can realize multidirectional and multidimensional shear. In order to further improve the detection accuracy of metrology system, vector diffraction theory is introduced. By comparing the vector and scalar light field, finally we can get the impact of vector light field on the performance of the shearing interferometer. This is for us to further improve the accuracy of detection system to provide rich information, which is crucial for the development of the lithography process.