The forming mechanism of microstructure of crossed holographic photoresist grating

Crossed-grating, as the standard element for metrology in two-dimensional precision positioning system, has been widely used in precision machine tools, highly sophisticated manufacturing and machining system. The technical indicators of crossed-grating, such as its diffraction efficiency and the efficiency equilibrium of the TE or TM polarized light are relevant to the microstructure of crossed-grating. While the structure of crossed-grating is determined by the microstructure of holographic photoresist grating. For exploring the evolution of microstructure of crossed holographic photoresist grating. In this paper, a new method for obtaining the variation curve of groove depth with exposure volume (the contrast curve of photoresist)is proposed, this method does not need a series of repeated experiments and is easy to operate compared with previous step experiments. The contrast curve of photoresist under different developing conditions (such as developer concentration and developing time) are analyzed. In addition, the top-view groove profile of crossed holographic photoresist grating under different process conditions are revealed too. The above research results provides a theoretical basis for the process parameters in holographic recording and developing of crossed holographic photoresist grating.