Research On A Photolithography With LCD Real-time Masks

The great demands for the micro-devices with micromation, lightweight and integration have vastly prompted the development of the micro fabrication technologies in information era. The MEMS and MOEMS techniques of the rapid development based on micro optics, microelectronics and micro mechanics have indicated an expansive future, which are applied in the aviation and space flight, optical communication, optical interconnected network, optical computing and other many high technique fields, and will also have a far-reaching impact on the military science and technologies, industry and the living of the people which we confront in the current century. The conventional photolithographic technology from VLSI technique exists in large limitations for the fabrication of micro optical, MEMS and MOEMS elements with three-dimension (3D) continuous structure. In this thesis, the research on the real-time photolithography technique for the fabrication of 3-D arbitrarily shaped microstructures has been carried out. Combined the advantages of programmable digital LCD system and projection photolithography system, which makes use of the flexibility of the former and the parallelism of the latter, the system of LCD real-time photolithography is proposed and set up through the sufficient investigation. Two methods based on the contour plane and the descritized gray scales for real-time mask are proposed and the relevant software for the techniques is developed. According to the characteristics of real-time masks, the optimal designs and fine corrections for the mask patterns have been developed on three aspects, including the processing of edges of mask patterns with the calculated gray level, the nonlinear correction of aerial image with the pre-distorted mask patterns, the nonlinear correction for post-processing through adjusting the display time of each mask pattern. The impacts of the LCD pixel structure on the fabricated result also are discussed. The new technique for the shape of deep relief structure through etching SHSG withenzyme is proposed and developed. At last, the simulations have been made based on the partial coherent imaging theory, and the micro-optical elements such as the micro lens, micro-cylindrical lens array, micro axicon array and so on have been achieved on SHSG through the applications of real-time mask and enzyme etching technique.Through the development of this technique, the conventional photolithography is greatly simplified as a single LCD mask can replace a set of conventional masks. Alignment between different levels of masks in conventional photolithography is no longer necessary if the LCD mask is used. Because the mask design can be adjusted in real time, it is comparatively easy to change the mask design to compensate any nonlinear effects in aerial imaging, in photo resist exposure, development and substrate etching processes. Thus it gives a new and effective approach for the fabrication of the arbitrarily shaped microstructure with 3-D continuous relief, and has very important significance to the development of micro optics and MOEMS.