Development of silicon accelerometers using epi-micromachining

摘要

This paper presents the development of accelerometers using the epitaxial layer as the mechanical structure. In this work epi-poly was chosen for the fabrication of the accelerometer structures. Epi-poly is a polycrystalline material deposited in an epitaxial reactor. This means that the mechanical structures can be deposited in the same step as the epitaxial layer used for the electronics. An extension to the epi-poly process has been used where after sacrificial etching to remove the oxide, anodic etching in HF is used to increase the airgap under the mechanical structures. This has the advantages of reducing vertical sticking and reducing parasitic capacitances. The paper describes the basic epi-poly process and the extension to a double sacrificial etching. Accelerometers have bene fabricated using both techniques and measurements have been made for both static and dynamic accelerations.