Measuring The Thickness Of Photoresist On Spherical Surface In Lithography Techniques

With the continuous development of lithography, laser direct writing on planar surface has matured, and laser direct writing on spherical surface has been the new direction. Changchun Institute of Optics, Fine Mechanics and Physics, and Fraunhofer Institute have made some achievements on the technology of laser writing on convex surface. Measuring the thickness of photoresist on spherical surface becomes an important issue, and is also the direction of this study. This paper introduces the study of spectral reflectivity method measuring the thickness of photoresist on spherical surface, includes of measurement principle, the build of various experiment optical path, experiment implementation and data analysis.Spectral reflectivity method measuring the thickness of photoresist on spherical surface, through laser irradiate the surface layer, using optical power meter or measuring tools such as CCD records the light intensity changes, the computer processing data to achieve the thickness of photoresist testing. Experiment system includes of laser, optical devices, measuring devices and computer.Research projects from photoresist on planar surface to photoresist on spherical surface. This paper introduces the research of planar transmission method, planar reflection method, spherical point method, and the preliminary experiment of whole spherical surface method. The different characters about substrate of photoresist planar layer, carried out the research of planar transmission method, planar reflection method, experimental data have been ideal to verify the spectral reflectivity method of photoresist layer thickness distribution theory is feasible. Through the study, we have found that, convex photoresist layer is uneven in theory. According to the characteristics of convex photoresist layer, carried out the research of spherical point method, get the convex photoresist layer thickness distribution, analyzed and discussed the error, give the method of improve precision. Base on the study of spherical point method, carried out the preliminary research of whole spherical surface method, build the light path of whole spherical surface, get some ideal experimental data, and put a certain foundation for follow-up experiments.This paper first presents a new and practical measurement of measuring the thickness on the planar and spherical surface, which has been verified by experiment. And also get the thickness distribution of photoresist.