Papers by Author: Hua Rong

Abstract: A fabrication process to manufacture SU8 photoresist microstructures is presented in which BP212 positive photoresist was used as sacrifice layer and SU8 was used as structure layer. No crack has been observed in the obtained microstructures. The relation between PEB temperature and stress gradient in SU8 film has been studied by measuring radii of released SU8 cantilevers made at different PEB temperatures.

Abstract: Stress gradient of a thin film along its thickness direction has important influence on performance of MEMS/NEMS devices. The measuring method based on curvature radius is a usual method for extracting film stress gradient. In this paper the error of the method has been analyzed using Finite Element Analysis software Coventorware, and the current theory has been modified according to FEA results to enhance its accuracy. Simulating results indicated that the accuracy of the method has been increased observably after correcting.

Abstract: The stress gradient of a deposited thin-film is a mechanical parameter that affects the performance of MEMS devices, so in-situ measuring stress gradient of a thin-film is great significant. A new in-situ measuring method based on a center-anchored circular plate is presented. The Mirau interferometer has been used to measure the out-of-plane height at the edge of circular plate, then the curvature radius of the plate and the stress gradient of the film can be calculated. The measuring method has been verified by CoventorWare. The accuracy of the presented measuring method is ideal. The advantages of the method also have been discussed.