Large Area Of ​​high-density Grating Based Nano-imprint Technology Developed

At the end of the 20th century and early 21^st century,the rapid development of nanotechnology will have a profound impact on human life and the progress of science and technology of all social sectors,which is expected to bring the fifth technological revolution.Within such a background,the semiconductor manufacturing industry,which is developing towards the direction of traditional optical lithography limit,starves for a new type of high-resolution,high efficiency and low-cost lithography technology.As one of the most promising method in the next-generation lithography,nanoimprint lithography attracts great attention.In addition,as an optical device,grating has a very wide range of application, particularly in the application of spectroscopy which made significant contributions to the development of human knowledge in the past 20tn century.However,subject to the capability of micro-processing technology,the development and application of high-density and large area diffraction grating have been extremely restricted. Profiting from the nanoimprint lithography,we will have the ability to fabricate cost-effective,high-resolution and large area transmission and reflective grating.Based on our earlier work on imprint into SU-8 resist,in this thesis we further extend this NIL technique to the fabrication of large area(10mm^* 10mm) transmission and reflective SU-8 gratings applicable in a broader wavelength range from 1μm (1000 lines/mm) down to 200 nm(5000 lines/mm) with various trench depths.The high optical transmittance of SU-8 in the visible range and its low volume shrinkage coefficient make the developed process an ideal candidate for high-volume manufacturing of various gratings at low cost.The etch properties of imprint templates such as the etch rate,profile and etching selectivity of Si over Cr as etch mask were carefully studied.The fabricated templates have a high aspect ratio over 3:1.The imprint property of SU-8 under various pressures and temperatures was systematically studied and agreed well with the simulation results.The effects of trench depth on diffraction intensity profiles were simulated and results show periodic diffraction orders with varying intensity distributions,which is in good accordance with the results from optical measurements. We also found a very high extinction ratio(over 2100) of transmissional polarized wave in the metallic grating.