Abstract
The purpose of this paper is to Mach-Zehnder interferometer (MZI) which is based on the thermo-optical effect (TOE) of the PECVD(Plasma-Enhanced Chemical Vapor Deposition) SiO2.The refractive index (n) of PECVD SiO2 can be controlled by the mixture of TEOS(Tetraethoxysilane Si(OC2H5)4),O2 and TMP(Trimethylphosphite P(OCH3)3) gases,The required refractive index is 1.487 and 1.479 for core layer and cladding layer. We use the software called‘Beam Prop” to simulate the MZI device.According to the simulation results,the back-side etching MZI device is made.The waveguide is fabricated by deposited a 10um thick buffer with TEOS, then deposited the core layer doped with TMP to modified its index. After deposition and lithography of Cr mask the core layer is then plasma etched. The sidewall roughness and vertical profile of the waveguide are the two key factors for optical performance of the waveguide. In order to reduce the switch power,we use MEMS technology to etch the backside wafer of waveguide to reduce the volume of silicon substrate and prevent the heat loss from conduction.