Technology And Experimental Study On Chemical Mechanical Polishing Of Sapphire Wafer

Sapphire crystal has excellent properties such as high strength,hard brittleness,high temperature resistance,chemical corrosion resistance and abrasion resistance.It has been widely used in the fields of semiconductor lighting,defense industry,aerospace and intelligent wear consumer electronics.As sapphire is a typical hard and brittle material,achieving ultra-precision machining with high efficiency and low damage has become an obstacle to its application.In order to achieve high efficiency,high quality,low cost,less damage and other processing requirements,the most widely used ultra-precision machining technology at home and abroad is chemical mechanical polishing.Chemical mechanical polishing is a combination of mechanical grinding and chemical etching.There is still a lack of in-depth understanding of material removal mechanism and technological factors in chemical mechanical polishing.Many aspects need further research.In this paper,the effects of single-side and double-side sapphire wafers on the polishing effect of single-side and double-side chemical mechanical polishing processes and polishing process parameters are studied experimentally.The research results have important guidance for the realization of high-precision and low-intensity ultra-precision machining of sapphire wafers.The specific research work in this article includes:Firstly,sapphire wafers were subjected to chemical mechanical polishing experiments on a Nanopoli-100 single-side correction ring polisher and a YH2M77110 high-precision vertical double-side grinding(polishing)machine.A single factor experiment was used to quantitatively analyze the effects of single and double-sided processing on the experimental results of chemical mechanical polishing,and the influence of process parameters on the effect of single and double-sided polishing was analyzed.Secondly,in order to improve the material removal rate and improve the surface quality of sapphire wafer during the chemical mechanical polishing process,the sapphire wafer double-side chemical mechanical polishing experiment was performed on the YH2M77110 high-precision vertical double-side grinding(polishing)machine.The effect of interaction between process parameters on material removal rate and surface roughness is studied.Two evaluation indexes of material removal rate and surface roughness are synthetically considered by weight matrix analysis method,and the polishing effect of the optimized results is verified by experiments.Finally,based on the theory of indentation fracture mechanics,a subsurface damage prediction model for sapphire wafer chemical mechanical polishing wasestablished.The polishing experiment was carried out,and the subsurface damage depth of the wafers was measured by cross-sectional microscopic observation and damage detection of the light intensity,and the reliability of the prediction model was verified.Combined with experimental results,the influence of process parameters and subsurface damage depth was analyzed.