What are the difficulties of silicon wafer cutting in general?
1. Impurity line marks: caused by impurities in the polycrystalline silicon ingot, which cannot be removed during the slicing process, resulting in related line marks on the silicon wafer.
2. Scratch line marks: caused by large SIC particles in the mortar or mortar agglomeration. During the cutting process, the SIC particles are "stuck" between the steel wire and the silicon wafer and cannot overflow, resulting in line marks.
Expression form: including the whole line mark and half line mark, concave, bright line mark, narrower than other line marks.
3. Dense line marks (intensive line marks): Due to the insufficient grinding ability of the mortar or the problem of the mortar circuit system of the slicer, the dense line mark area appears on the silicon wafer.
4. Dislocation line marks: Line marks are caused by the fact that there are foreign objects such as mortar on the surface of the hydraulic clamping device of the slicer or residual glue on the pallet, which causes the hydraulic device and the pallet to be unable to be clamped and the screws of the pallet are loose.
In the whole cutting process, the viscosity of the cutting fluid, the particle shape and particle size of the silicon carbide powder, the viscosity of the mortar, the flow rate of the mortar, the speed of the steel wire, and the tension of the steel wire play a major role in the quality and yield of the silicon wafer. And the feed rate of the workpiece, etc.
Line marks and TTV: Line marks and TTV are relatively headaches encountered in the processing of silicon wafers, and there will be a knife from time to time, which is hard to prevent. TTV appears when the knife is inserted, and line marks are easy to appear when the bow is retracted.
