Development of a mechanical polysilicon layer for surface machined microelectromechanical systems using TEM, SEM, and Raman spectroscopy

摘要

Low stress polysilicon is required to replace the standard gate polysilicon for the mechanical layer in a microelectromechanical (MEMs) process. A uniform structure through the thickness of the layer is required to stop freed beams curling up. In this paper electron microscopy technique have been used to identify such a material. TEM was used to analyse the structure of polysilicon layers, and SEM to show up any residual stress gradient large enough to curl beams. A suitable process has been identified and used to fabricate accelerometers. Raman spectroscopy is currently being investigated to map stress in these devices.