Ultra-thin sapphire wafer processing is receiving increasing attention in the LED substrate industry. In the cascade clamping method, the motion state of the wafer determines the uniformity of material removal, while the motion state of the wafer is related to its friction coefficient in the biplane processing system, but there is little relevant literature discussing the relationship between the motion state of wafer and friction coefficient. In this study, an analytical model of the motion state of sapphire wafers in the layer-stacked clamping process based on the frictional moment is established, the effect of each friction coefficient on its motion is discussed, the base plate of different materials and different roughness are experimentally studied, the layer-stacked clamping fixture is prepared in this way, and finally the failure form of the limiting tab is analyzed experimentally. The theoretical analysis shows that the sapphire wafer is mainly driven by the polishing plate, while the base plate is mainly driven by the holder, and the rotation speed of the two is not the same; the material of the base plate of the layer-stacked clamping fixture is stainless steel, the material of the limiter is glass fiber plate, and the main form of failure of the limiter is to be cut by the edge of the sapphire wafer and damage the material structure.

Ultrathin sapphire wafer is of great signi cance in the semiconductor eld. In order to explore the effective clamping method of ultrathin sapphire wafer in double-side polishing, this paper studied the characteristic of Layer stacked clamping (LSC) method on polishing ultrathin sapphire wafer with doubleside polishing machine. A self-made friction force test platform was built for learning the friction force between sapphire wafer and baseplate with different baseplate (stainless steel, cast iron, aluminum alloy) and different baseplate surface roughness (R a 3.6 nm, 68.2 nm, 210.1 nm, 517.9 nm). Single factor polishing experiments were carried out on baseplate with different atness (PV value 5.3 µm, 9.8 µm, 19.9 µm, 29.7 µm) and different thicknesses (0.082 mm, 0.104 mm, 0.119 mm). The double-side polishing experiments were carried out to compare the polishing performance on the ultrathin sapphire polishing between LSC method and traditional para n bonding method. The results show that the friction force of stainless steel and iron increase under the adsorption of droplets. Stainless steel performs higher friction force and is more suitable for making the baseplate. The inner fringe of limiter was cut off by the edge of the sapphire wafer and a slope was thereby formed. According to polishing results, LSC method has higher processing e ciency per unit time. The surface roughness, atness and material removal rate are better than para n bonding. Finally, a smooth surface with surface roughness (R a ) 1.3 nm and atness (PV) 0.988 µm was obtained with LSC method.

Ultrathin sapphire wafer is of great significance in the semiconductor field. In order to explore the effective clamping method of ultrathin sapphire wafer in double-side polishing, this paper studied the characteristic of Layer stacked clamping (LSC) method on polishing ultrathin sapphire wafer with double-side polishing machine. A self-made friction force test platform was built for learning the friction force between sapphire wafer and baseplate with different baseplate (stainless steel, cast iron, aluminum alloy) and different baseplate surface roughness (Ra 3.6 nm, 68.2 nm, 210.1 nm, 517.9 nm). Single factor polishing experiments were carried out on baseplate with different flatness (PV value 5.3 µm, 9.8 µm, 19.9 µm, 29.7 µm) and different thicknesses (0.082 mm, 0.104 mm, 0.119 mm). The double-side polishing experiments were carried out to compare the polishing performance on the ultrathin sapphire polishing between LSC method and traditional paraffin bonding method. The results show that the friction force of stainless steel and iron increase under the adsorption of droplets. Stainless steel performs higher friction force and is more suitable for making the baseplate. The inner fringe of limiter was cut off by the edge of the sapphire wafer and a slope was thereby formed. According to polishing results, LSC method has higher processing efficiency per unit time. The surface roughness, flatness and material removal rate are better than paraffin bonding. Finally, a smooth surface with surface roughness (Ra) 1.3 nm and flatness (PV) 0.988 µm was obtained with LSC method.