FABRICATION OF LOW-STRESS DIELECTRIC THIN-FILM FOR MICROSENSOR APPLICATIONS

A method of fabricating low-stress dielectric thin film as the support ing material of micromachined devices is reported. The film is process ed by post thermal oxidation of silicon-rich nitride (SN) deposited on silicon substrate by LPCVD. Due to the compensation on the nitride by its top oxide, an ultra-low residual less than 10 MPa can be obtained with proper oxidation scheme. Characteristics of the oxidized nitride were analyzed by Auger electron spectroscopy (AES) and ellipsometry. Large floating membranes of 4 x 4 cm(2) and 400-nm thick can be made b y this method with TMAH etching.