Research On Key Technology Of Micro-nano Grating Etching Based On Holographic Lithography

Micro-nano gratings are one of the important micro-optical components,which have the advantages of simple structure and easy integration.Bragg gratings are often used as semiconductor lasers and optical filters due to their good selective effect on light waves of specific wavelength Mode selection components for optoelectronic devices such as devices.At present,holographic lithography is one of the preferred technologies for preparing micronano gratings.However,due to the limitation of the exposed grating pattern,the thickness of the photoresist used is relatively thin,resulting in insufficient photoresist to block the bombardment of particles during dry etching of the grating It brings greater difficulty for the later grating etching.In order to solve the problem that the grating is difficult to etch in the process of preparing the grating by holographic lithography,a scheme of using a metal hard mask to provide a barrier layer for the dry etching of the micro-nano grating is proposed.In this dissertation,a Distributed Bragg Reflector(DBR)semiconductor laser is taken as the research object,and a series of researches are carried out on the key technologies for preparing micro-nano Bragg gratings based on holographic lithography.The research contents include: 1)Exploring the basic working principle of Bragg gratings based on coupling mode theory and transmission matrix method,designing Bragg gratings for 976 nm band reflection,and determining its parameters such as period,duty cycle,and etching depth;2)Design and build the light path of the holographic exposure system,optimize the holographic lithographic process parameters,and obtain the periodic grating pattern with good morphology;3)Investigate the preparation process of micro-nano grating hard masks,use metal nickel(Ni)as the hard mask material,and use Lift-Off technology to obtain micronano grating hard masks;4)Design a micro-nano grating preparation process based on holographic lithography technology,optimize various process parameters,prepare and obtain a grating sample with a groove width of 300 nm and an etching depth of 1454 nm,and its aspect ratio is about 4.9;5)Designed a 976 nm DBR semiconductor laser device manufacturing process based on holographic lithography technology,and carried out preparation research on the device,and obtained an output laser with a center wavelength of 976 nm and a spectral width of about 0.3nm.