Study On The Surface Integrity Of Silicon Wafers With Taping In Ultra-precision Grinding

With the development of integrated circuit(IC)technology,more and more requirements are put forward for miniaturization,high performance and low cost of electronic products.Thin large sized silicon wafers as the main IC substrate material are developed to the maximization of diameter and the minimization of thickness.Due to its distinct properties such high hardness and brittleness,anti-radiation and heat resistant,silicon wafers are required to have low-damage and high accuracy in the process of back-grinding.At present,in order to effectively protect the patterned wafers and reduce fragmentation during the process of manufacturing,transportation and storage,a method that taping in back-grinding process were widely-used.In this paper,resin-bonded diamond grinding wheel was used to reduce the thickness of silicon wafers with taping in back-grinding process.Therefore,a thorough understanding of how taping influences the surface/subsurface damage,peak-to-valley,edge chipping and residual stress of silicon wafers were obtained in diamond grinding.Simultaneously,the optimum selection of the tape in the process of silicon wafers grinding is also proposed.The main research works and conclusions are as follows:(1)In this paper,#600 and #2000 resin-bond diamond grinding wheels were conducted to investigate the influences of taping on the peak-to-valley(PV),surface roughness and subsurface damage of silicon wafers after grinding.On the basis of grinding principle,a predictive micro-geometric model of taping in back-grinding process after self-rotating grinding was established.It was found that the PV,surface roughness and subsurface damage of silicon wafers with taping was slightly larger than that without taping protection,although taping in back-grinding process will protect the patterned wafers and reduce fragmentation.At the same time,this study provides the instructions for the determination of the tape thickness for precision back-grinding of silicon wafers in IC manufacturing.(2)In this paper,silicon wafers with taping were ground to 400 ?m by #600 resin-bond diamond wheel.The effect of taping on the quality of silicon wafers is evaluated by measuring the size of edge chipping of silicon wafers.The experimental results showed that the edge chipping of silicon wafers with taping were slightly higher than that without taping protection,although taping will reduce the fragmentation and optimize grinding process.However,the thin tape has an obvious negative effect on edge chipping than the thick tape.At the same time,it was found that the difference in edge chipping size in the <110> crystal orientation and the <100> crystal orientation is not significant.(3)Based on the minimum strain energy theory,the theoretical stress-curvature model about the relationship between deformation,wafer thickness and tape thickness was established.It is also found that taping will provide effective protection of silicon wafers,although the residual stress of the silicon wafer with taping is a little larger than that without taping protection.Raman spectra results show that the stress-curvature model of silicon wafer is more accurate than the existing model.