The Influence On Geometric Parameters Of Silicon Wafers During Free Abrasive Multi-wire Sawing

Mono-crystalline silicon wafer is the main base material in the IC manufacturing process.The slicing process plays an important part of the monocrystalline silicon wafer preparation process,which has an important impact on the geometry parameters of the silicon wafer.Many researchers had proved that the thermal accumulation during cutting was the main reason for the change of wafer geometry.Multi-wire sawing technology has become the main way of slicing because of its high efficiency,low cutting loss and adaptability to large diameter silicon ingot cutting.With the increasing requirements of semiconductor devices on the geometry parameters of silicon wafer,reducing the deformation of silicon wafer in the slicing process has become an urgent technical problem.In this paper,the process parameters,wire guide rollers,steel wires and slurry which affect the geometry parameters of silicon wafer in the slicing process were studied.In order to analyzed the influence of free abrasive multi-wire sawing on the geometric parameters of silicon wafers.1.Based on summarizing the defects of equal removal rate cutting model,constant cutting surface spacing slicing model is proposed.The orthogonal experiment was carried out to verify the influence of process parameters on the geometry of silicon wafer,table speed,wire tension and the usage times of slurry were used in experiments.The formation mechanism of the cutting surface is revealed with the wire reciprocating motion,and the reason why the width of the cutting surface is different between the incoming side and the outgoing side is explained.2.Analyzes the discipline during the constant cutting surface spacing slicing on the surface angle and the space change with the cutting position along the edge of the wafer through the experiment.Also,the reason of this phenomena was explained in this section.The relationship between the wafer bending direction and the cutting speed is analyzed.The wafer bending direction can be changed by changing the cutting feed speed.3.The results show that the heat value generated by the constant cutting surface spacing model is lower than that generated by the equal removal rate model,and the temperature changed more smoothly during the cutting process,and the warpage value of the silicon wafer after cutting was reduced,which proved that the model can effectively reduce the warpage value of the silicon wafer after cutting and flatten the bending shape of the silicon wafer.4.The influence of groove machining process on groove quality characteristic parameters was analyzed.The influence of groove quality characteristic parameters on the geometric parameters difference of silicon wafer after cutting was analyzed experimentally.Also analyzed the change law of physical characteristic parameters with the increase of slurry mixing time and cutting times and put forward that the mixing time of slurry preparation should be controlled within 24 hours.The influences of the times of slurry cutting used and the shapes of steel wire during the slicing process on the geometric parameters of silicon wafer were analyzed.