Study On Friction Mechanism And Characteristics Of Mask Based On Contact Therory

As the key equipment of large scale integrated circuit manufacturing,the continuous improvement of lithography accuracy is very important for the development of integrated circuits.At present,in the process of high acceleration and high acceleration of 14 nm lithography machine,the increase of the acceleration of the mask table results in a significant increase of the slip between the mask and the sucker in the motion process,which seriously affects the accuracy and product yield.In order to solve this problem,it is necessary to establish a friction model between mask and sucker adsorption surface,and study the friction behavior and slip mechanism between mask and sucker adsorption surface.Therefore,starting with the establishment of friction mechanism between mask and sucker,it is of great significance to guide the sliding suppression of mask.Under the above research background and technical requirements,many friction calculation models are analyzed and compared in this paper,and the following research work is carried out:(1)An interface static friction model based on GW(Greenwood-Williamson)statistical theory and contact theory is established.Combining the theory of DMT(DerjaguinMuller-Toprov)adhesion contact with GW statistical theory,the normal force and the maximum static friction force of the micro-convex body contact are obtained.Considering the different elastic-plastic deformation states of the micro-convex body,the contact model of KE(Kogut-Etsion)is established.The normal force,maximum static friction force and friction coefficient of the contact interface between the whole mask and the sucker are calculated.Model.The effects of interface spacing and standard deviation of rough peak height on mechanical parameters are analyzed,and the corresponding method of increasing static friction force is proposed to suppress slip.(2)An interface static friction model based on fractal theory and contact theory is established.Compared with GW statistical theory,fractal theory has obvious advantages in analyzing interface surface morphology,which is not limited by sampling length.WM(Weierstrass-Mandelbrot)function is used to simulate rough surface morphology,which is combined with contact theory.A fractal contact model of MB(Majumbar-Bhushan)is established,and the normal force,maximum static friction force and contact force of the interface between mask and sucker are calculated.The calculating model of friction coefficient is analyzed.The law of action of fractal dimension and scale coefficient,which are two important parameters describing fractal characteristics,on the mechanical parameters is analyzed.The corresponding method of increasing static friction force is proposed to suppress slip.(3)Designing and completing relevant verification experiments.According to the surface simulation calculation of WM,the deviation range of fractal dimension measured by structural function method is 0.2%~7.66%,which has high accuracy.Atomic force microscopy(AFM)was used to measure the surface topography of the mask and the suckers of the two materials,and the fractal dimension and scale coefficient were calculated by using the structure function method.The maximum static friction validation experiment was designed,the workbench was set up,the maximum static friction coefficient under different normal loads was measured and compared with the two theoretical models.The results show that the calculation error based on MB fractal contact model is smaller than that based on KE contact model.The average deviation of MB fractal contact model is 0.0231 and 0.0068,respectively,in the case of sucker contact between the two materials.The values are more consistent.