Characterization and modeling of polysilicon MEMS chemical-mechanical polishing

Abstract

Heavily used in the manufacture of integrated circuits, chemical-mechanical polishing (CMP) is becoming an enabling technology for microelectromechanical systems (MEMS). To reliably use CMP in the manufacturing process, designers must be able to accurately predict the CMP process and control final surface uniformity. This thesis extends integrated circuit CMP knowledge towards MEMS applications. Experiments were performed to characterize polysilicon MEMS CMP. A new test mask was created which contains test structures relevant to MEMS. Both single and dual material polish experiments were carried out and the resulting data fit against an adapted step height density model. Results show that integrated circuit CMP models are applicable to MEMS CMP, but the models need to be adjusted in order to contend with issues inherent to MEMS CMP. Further study may be necessary to accurately and completely characterize polysilicon MEMS CMP and make improvements to the models.