Eigenfrequenzbestimmung von Wafern

Abstract

Wafers are transported through the manufacturing lines in modern semiconductor factories with automated, rail mounted and ceiling mounted vehicles (OHT). The resulting vibrations, for example, by shaving or lifting and lowering operations, are transferred to the transport container and finally to the wafers. If the operating frequency from the transport and the natural frequency of the respective wafer is accord, a resonance is formed, which can lead to the breakage of the wafers and high economic damage. In order to avoid this, the natural frequencies of the involved system elements have to be investigated. In a vibration test bench, the natural frequencies of wafers were determined separately and in conjunction with their transport box, the Front Opening Unified Pod (FOUP). As in operation, the FOUP was hanging mounted on the provided fixture and excited with a shaker. By means of a modal analysis in the FE simulation, the natural frequencies and frequency profiles were determined and the vibration forms were reproduced at the respective measuring positions. Furthermore, simulations as well as experimentally vibration reducing measures were carried out. The results see a stiffening of the fixture of the FOUP as the most effective solution.