Research On The Fabrication Technology Of Micro-Optic Devices Based On Micro Imprint

Since GaN-LED has been studied on the application of solid-state lighting, it is still an important problem that how to enhance the light extraction efficiency of GaN-LED chips. It has been reported that, the internal quantum efficiency (IQE) reaches more than 70% while the external quantum efficiency is only about 14%. So, how to improve the external quantum efficiency is significant for semiconductor solid-state lighting.In order to solve the problem, this paper proposes a fabrication method of microlens array using CEM (contactless embossing of microlenses) which is based on micro imprint. Compared with others, this method is easier to implement and lower cost of materials, and what is more important is that the microlens array can be fabricated in large area and with rapid speed.At first, this paper introduces kinds of methods which have been invented to increase the light extraction efficiency of LED, such as surface texturing and photonic crystal effect. By the comparison of these methods, this paper points out that to fabricate micro optical structures on the LED chips is an efficient way to solve the problem. Then the paper introduces a fabrication technology of microlens array based on micro imprint. After the analysis of polymer's optical properties, mechanical properties and thermal properties, the polymeric materials which will be used for imprint experiments have been chose. This paper fabricates the quartz mold using a way which combines lithography with ICP etching, and also analyses factors relate to the formation quality of molds during the whole procedure. By the imprint experiments, the paper analyses relations between process parameters and qualities of polymer samples. At the same time, the paper finds out the differences between PMMA, PS and PC by the analysis of different deformation contours. In addition, this paper studies the principle of CEM by finite element analysis, and builds a model of CEM by Ansys.At last, the paper presents a series of improvements in the structure and performance of the micro imprint equipment, such as adding active de-embossing module and XY axis micro-displacement plat.