Microlens Array Photolithography Projection System

Microlens array is an important fundamental device in Micro-Optics, for it has the functions of focusing, diverging, collimating, imaging and transforming in arrays, also it has so many advantages such as high density, convenient fabrication and easy coupling with other plane devices. It goes with the tide of miniaturizing and integrating in optical devices. It has wide prospects for application in photolithography, fiber communication and optical information processing etc.In the thesis, the physical mechanism and fabricating method of microlens array are studied theoretically and experimentally. Guided by the theory of melting resist technique on microlens array, the formula of the thickness of melting resist to overcome some disadvantage on melting resist technique and the optimized melting resist method is suggested. The influence of the best contact angle between the melting resist and substrate to the surface formation of microlens is discussed. Because the transparence and anti-fraying performance of the photoresist microlens array is not good, we can obtain better ones by combining melting resist technique with reactive ion etching for transfering the profile to the substrate. The measure method of the parameter of the refractive microlens array is discussed and tested by simple equipment. On the base of applied optical theories, the imaging properties of microlens array are analyzed.The multiple imaging of the microlens arrays is studied theoretically and experimentally, and a microlens projection photolithographic system is designed and fabricated. Integration of the system is described, the characteristics of the photolithographic imaging system are analyzed in detail. Finally, Experimental measurement result and evaluation of the system are provided. Compared with conventional proximity printing, the microlens photolithographic projection system is a new novel technique. For a large area of mask, especially for some non-planar substrates, the system can provide better image and larger working distance.