Design Of Silicon Wafer Suspention Using Gas Vortex Method And Design Of Its Delivery System

With the continuous development of integrated electronics technology, the diameter of silicon wafer is becoming larger and larger, the thickness of wafer is becoming smaller and smaller, the requirements of the flatness and accuracy of the wafer surface is getting more and more intense. As the emergence of the era of 450mm-diameter-silicon-wafers, the accuracy requirements has been increased to nano-scale. Traditional silicon wafer clamping method is easy to damage the silicon, causing scratches on the silicon surface. It may not meet the new requirements. In this paper, a vortex suction cup is researched and designed according to the principle of negative pressure in the vortex center, so that the silicon suspended in the air to avoid the damage of the silicon surface. Compared to the other holding methods, this method has the advantage of distributing surface stress, which may minimize the harm to silicon surface. Due to the instability of the swirl, a single vortex sucker cannot achieve the normal clamping function. So this paper introduces a kind of integrated suction cup, which realized stable clamping of silicon wafer. This integrated suction cup is very suitable for large-diameter silicon wafer clamping. Further more, automated clamping of the wafers is realized through PLC programming. The main work is as follows:1,The ideal vortex and actual vortex produced by the sucker is theoretically analyzed with the theory of fluid mechanics. A variety of parameters that may affect the function of silicon wafer clamping is introduced, including structural parameters such as gas chamber radius, gas chamber height, the shape and size of the inlet holes and its location relative to the upper surface of the gas chamber; external parameters such as inlet air pressure and flow rate. The possible impact of these parameters on the silicon wafer is predicted.2,Pressure distribution on the surface of the silicon wafer is measured using pressure sensor, clamping force is measured using electronic weigher. The influence of various parameters, such as gas chamber radius, gas chamber height, inlet pressure, to the clamping force is analyzed. The best set of experimental parameters is selected for the measurement of wafer surface pressure distribution.3,According to the theoretical and experimental analysis, single vortex sucker can only weaken the torque, rather than eliminate it. Thus a few vortex suction cup with special structure are designed.4,Based on the experimental studies of single suction cup, integrated suction cup is invented. In this way, reverse, flip, shock of the silicon wafer is eliminated, however the translation still exists. A kind of automatic bar mechanism activated by pneumatic motor is designed to eliminate the translation phenomena.5,Pneumatic transmission method is utilized. Automated clamping of the wafers is realized through PLC programming...