Feng Fei

Smooth Surface Morphology of Hydrogenated Amorphous Silicon Film Prepared by Plasma Enhanced Chemical Vapor Deposition

Influence of the parameters of plasma enhanced chemical vapor deposition (PECVD) on the surface morphology of hydrogenated amorphous silicon (α-Si:H) film was investigated. The root-mean-square (RMS) roughness of the film was measured by atomic force microscope (AFM) and the relevant results were analyzed using the surface smoothing mechanism of film deposition. It is shown that an α-Si:H film with smooth surface morphology can be obtained by increasing the PH3/N2 gas flow rate for 10% in a high frequency (HF) mode. For high power, however, the surface morphology of the film will deteriorate when the SiH4 gas flow rate increases. Furthermore, optimized parameters of PECVD for growing the film with smooth surface were obtained to be SiH4: 25 sccm (standard cubic centimeters per minute), Ar: 275 sccm, 10%PH3/N2: 2 sccm, HF power: 15 W, pressure: 0.9 Torr and temperature: 350°C. In addition, for in thick film deposition on silicon substrate, a N2O and NH3 preprocessing method is proposed to suppress the formation of gas bubbles.

A New Method for Protection of Anchors in Releasing Microstructure by using XeF2 Etching Process

This paper presents a protection technology of anchors to use xenon difluoride etching process to release micro structure in Micro-Electro-Mechanical Systems processing. This technology is based on deep reactive ion etching and two-time thermal oxidation technology. Firstly, the trenches around the anchors are formed by using deep reactive ion etching. Secondly, the trenches are filled with thermal silicon dioxide that is hardly etched by xenon difluoride. Robust silicon anchors with protection layer silicon dioxide have been fabricated. Then, 100times100 suspended micro structure array, in which each element consists of two anchors and a micromirror supported by two beams, has successfully been fabricated by using this technology.

Novel all-light optically readable thermal imaging sensor based on MEMS technology

This paper presents a novel all-light optically readable thermal imaging sensor based on the bulk-MEMS technology. The sensor contains a focal plane array (FPA) consisting of m /spl times/ n movable micromirrors supported by bimaterial beams. As infrared radiation applied on FPA, a temperature gradient generated on the bimaterial beams leads to the deflection of beams and resulting in proportional displacement of this movable micromirror. A visible optical system is used to measure the displacement of the movable micromirrors of the FPA using Fabry-Perot interferometry. Our Al/SiO/sub 2/ micromirror structure is optimized to achieve a thermo-mechanical sensitivity of 10/sup -8/m/K. The FPA consisting of 50/spl times/ 50 movable micromirror array has been successfully fabricated by using bulk MEMS technology.