Fabricating a variety of micro-optics structures using anisotropic etching of silicon

A variety of micro-optics structures can be fabricated using a dual-step anisotropic etching of KOH: H2O over (100) silicon. A key step of this method is the design of mask layout. In accordance with the expected profile, this paper implemented a set of algorithms through computer programming to design the mask, and after setting a set of parameters, the final etching profile can be simulated. According to the data of the mask layout generated by the program, a lithography mask is fabricated, and then through the single-step lithography and dual-step wet etching, the expected profile is acquired. The mask can be fast and efficiently designed using this method, and through follow-up procedures, many kinds of aspherical and irregular micro-structures can be obtained. In this study, a series of 512x512 arrays of concave lenses are designed using the algorithm, and then the follow-up procedures are carried out using the most appropriate corrosion issues calculated by the program, and finally get a good result. At the end of this study, the lens' surface profile, roughness, and optical performance, etc, are tested. Test results show that the micro lens are very neat, and the hole size and depth of each unit have basically the same size. The surface profile and roughness already achieve optical mirror requirements, and the structures have good optical performances.