Study On Surface Texturing Of Si By Laser Interference Lithography And Micro Tribological Properties

As the characteristic size continues to scale into the micro/nanometer era, due to scaleeffect and surface effect, problems of friction and adhesion are key factors to the rapiddevelopment of M/NEMS. Surface texturing of micro components is one of the researchdirections of tribological design in M/NEMS. As a newly preparation method of microtexture, laser interference lithography has advantages of simple equipment, greatefficiency, large areas processing and so on. In this paper, micro texture with different typeand size was fabricated on silicon surface by laser interference lithography, the frictionalproperty of which was tested by AFM. The main research contents and conclusions are asfollowing.1. The basic expressions for intensity distribution of interference were carried out,according to Maxwell photoelectric equations. Simulations for the intensity distribution oftwo-beam interference with single exposure and double exposure were expressed, usingMATLAB software. The simulated results for two-beam with single exposure and doubleexposure interference lithography and two-scale texturing lithography showed that laserinterference lithography was a good method to fabricated periodical texture includenanogrooves, holes array and pillars array over large area, and the method fabricating twoscale was feasible.2. The optical setup of two beams laser interference was built based on the simulationresults, and carried out the process of laser interference lithography. Nanogrooves and gridtextures were obtained on photoresist by two beams with single exposure and doubleexposure interference lithography, which was good duplicated to silicon surface bychemical wet etching. Through changing θ and exposure dose, various nanogrooves, holesand pillars array with different pitch and space width on silicon surface were fabricated.Two methods for fabrication of two-scale texture were presented, the experimental resultsof which were good.3. Frictional property of the textured silicon surfaces with different type and sizewere tested by AFM. In pin-flat contact, frictional force of textured surfaces were greaterthan sooth surface’s, and the friction force of nanogrooves decreased with the increasingof coverage rate. In ball-flat contact, textured surfaces were antifriction and adhesivereduction. In C-AFM mode, investigation on the interface friction properties underexternal electric field by AFM, the results of which showed that frictional force decreasedwith the increasing of bias firstly and then increased.