Research Of Non-contact Wafer Holder

Semiconductor manufacturing technology is the core of electronic and information industry, and one of the most important high-tech that promotes the development of national economy and society informatization, while the gripping and transpotation device of silicon wafer is an important part of semiconductor manufacturing process. Now gripping device is contact vacuum suction cup, and it is easy to produce surface contamination, scratches, distortion and other defects due to direct contact with wafer surface, and will cause reject rate increases, low productivity and other issues in nano-chips manufacturing. The trend of silicon wafer is large diameter, which has set higher demands and challenges with semiconductor manufacturing technology.In recent years, researchers of several countries attach great importance to the research of non-contact wafer holder technology. Non-contact wafer holder which makes use of aerodynamics theory has advantages of low limit to wafer material and shape and has no pollution to working environment, so various research institutions have considered it as the the most promising way for wafer holder.In this paper, due to special requirements of gripping course of wafer holder, the following major tasks were finished:1. Analyze the principle of vortex-type non-contact holding device from the view of aerodynamics, and finish simulation study using Solidworks to establish flow-field model and CFD simulation software to finish numerical calculation.2. Design suction cup structure in basis of theoretical analysis and flow-field simulation results. Use high-precision electronic balance to measure acting force, and make it clear of the relationship between acting force and structure parameters and work conditions of the suction cup.3. In order to weaken the wafer rotation and increase the acting force, an improved structure combined with diffluence-hole and stability-net was proposed. Through the simulation and experiment, we get the conclusions: diffluence-hole and stability-net can improve the stability of gripping process and increase the actring force, but cannot eliminate the phenomenon of wafer spinning.4. According to the above theoretical analysis and experimental research, the final structure of the suction cup is proposed. The combination of several suction cups can provide adequate acting force, and, more importantly, effectively resolve the problem of wafer rotation. With the help of additional leader structure around the suction cup, silicon wafer can finish the horizontal move.5. To validate gripping effect and show work process of the suction cup, we designed pneumatic transmission system. The work includes selecting pneumatic components and making use of PLC to control the system.