超精密晶圆减薄砂轮及减薄磨削装备研究进展OA北大核心CSTPCD

In the later stage of the chip manufacturing process,the ultra-precision wafer thinning process can effectively reduce the packaging volume,conduction resistance,and improve the thermal diffusion efficiency,electrical and mechanical properties of the chip.At present,the mainstream process is to thin wafers using ultra-fine diamond grinding wheels and high stability ultra-precision thinning grinding machines,due to the constant contact area of the wheel and the wafer,with a stable grinding force,low breakage rate,which can achieve high-precision,high-efficiency,and high stability non-destructive surface processing for large-sized wafers.The paper focused on the current research progress of ultra-precision wafer thinning grinding wheels,in which the wheels were mainly composed of three elements:abrasives,bond and pores.In terms of abrasives,the current research status of hard abrasives for mechanical grinding was summarized,including the preparation methods and grinding performance of foamed diamond,diamond agglomerated abrasives,surface micro-edged diamond.Compared with the traditional monocrystalline diamond,monocrystalline diamond had a single grinding edge,and the overall sharpness of the grinding wheel was insufficient,and the micro-area multi-edge treatment of the diamond surface could effectively increase the overall life and sharpness of the grinding wheel.Meanwhile,the research progress of the soft abrasives for chemical-mechanical grinding was reviewed,and the chemical-mechanical grinding mechanism and the material removal model of soft abrasive wheels under the action of multi-energy field coupling were summarized.In terms of bond research,the advantages and disadvantages of metal,resin and vitrified bond and their applications in wafer thinning grinding wheels were reviewed.Due to the high intrinsic strength and poor self-sharpening of the grinding wheel,metal bond was partially applicable to the rough grinding process of wafers,while resin bond was poor in heat resistance,which was likely to oxidize and decompose,and poor in wettability with diamond due to its own material properties,and could not withstand heavy-loaded grinding.Due to the limitations of metal and resin bond in ultrafine-grained grinding wheels,vitrified bond,with its high strength,adjustable porosity,and good interfacial wettability with diamond,was the preferred choice for the preparation of ultra-precision wafer-thinning grinding wheels.The paper mainly focused on an overview of the current research progress in the improvement of the intrinsic mechanical strength of vitrified bond and the interfacial wettability between vitrified bond and diamond.In terms of ultra-fine-grained grinding wheel preparation technology,due to the large surface energy of micro-nano diamond,using traditional processes to prepare grinding wheels may cause abrasive agglomeration and affect processing quality.On this basis,the application research of new process methods such as sol-gel method,polymer network gel method,electrophoretic deposition method and gel injection molding method and structured grinding wheel in the preparation of ultra-fine grain thinning wheel were summarized.The paper also reviewed different semiconductor wafer thinning processes,including electrical discharge grinding,plasma chemical vaporization machining,and electrolytic in-process dressing grinding.The paper also summarized the research progress of the current wafer thinning processes with ultra-precision thinning equipment,and pointed out the future development direction of semiconductor processing tools and equipment.