Measurement And Characterization Of Surface Topography In Ultra-fine Grinding Of Monocrystalline Silicon Wafer

Integrated Circuit(IC)is the foundation of the modern information technology development.Monocrystalline silicon is the main substrate material in the manufacturing process of the integrated circuit.As a typical hard-and-brittle material,monocrystalline silicon has high hardness and brittleness.To solve the matters of low efficiency and high cost of traditional processing technology,ultra-fine grinding technology with workpiece rotation is considered as the mainstream technology to achieve high precision and high efficiency processing of monocrystalline silicon wafers.There are mainly three material removal modes in the hard-and-brittle materials grinding process:brittle removal mode,plastic removal mode and brittle-plastic transition mode.When the material is completely removed by plastic mode,a higher surface quality can be obtained.Meanwhile,the ultra-fine grinding surface topography features are closely related to the performance of the parts.In order to control the grinding process and meet the requirements of part performance evaluation,it is necessary to measure and characterize the grinding surface topography.Existing measurement standards are mainly for contact(stylus)measurement method.There is no relevant regulation for other measurement methods.Due to the influence of researchers'subjective factors,different results can be obtained for the same measurement surface.In addition,for the accurate identification of brittle-plastic transition state of grinding surface of hard-and-brittle materials,there is still a lack of reasonable and efficient characterization methods.Based on the above analysis,the research contents of the article are as follows:(1)The existing methods of surface topography measurement and characterization are studied.The related performance parameters,measurement principle and error factors of three-dimensional surface profiler and atomic force microscopy are analyzed.The influence of filter cut-off wavelengths and sampling lengths on surface roughness measurement results is discussed.The results show that the measurement results of surface roughness vary greatly when the selected cut-off wavelengths and sampling lengths are different.(2)Based on the platform of MATLAB,a power spectral density calculation model was established.The influence of surface high frequency and low frequency topography features on surface roughness is analyzed in frequency domain.By analyzing the effective frequency band of power spectral density curve under different sampling conditions,a method to measure and evaluate the grinding surface quality of monocrystalline silicon wafer accurately is proposed,and the rationality of the method is verified.(3)An effective recognition method of the brittle-plastic transition features of monocrystalline silicon grinding surface based on the surface texture aspect ratio parameter Str is proposed.For the characterization of brittle-plastic transition features of grinding surface of hard-and-brittle materials,there are mainly three methods in the paper:the traditional method based on parameter Sbf,the methods in existing literature based on parameter S_c and parameter D_L,and the proposed method based on parameter Str.By comparing and analyzing of the methods,the correctness and effectiveness of the proposed method are verified.