Abstract: A new levitation theory is introduced to achieve non-contact wafer handling, and eliminate the production defects that arise from the physical contact between the holder and wafer surface. This method, according to aero-dynamics, produces vortex flow in semi-closed flow passage, and then results in non-contact clamping in virtue of the dynamic balance among the negative pressure of vortex center, the positive pressure of air overflowng and the weight of wafer. The levitation theory is analyzed, and a prototype of vacuum cup with two nozzles is designed. Numericl simulation of the positive pressure rotary flow field of perfect gas in the cup is carried out by using the RNG k–ε turbulence model. Finally the adsorption force of the cup is tested. The test results indicate that the vortex vacuum cup is able to carry out non-contact clamping, and the adsorption force acting on the wafer is closely related to the working distance, inlet pressure, and structural parameters of the cup.

Key words: Non-contact handling, Vacuum cup, Vortex flow, Wafer holder