Low Stress Polycrystalline SiC Thin Films Suitable for MEMS Applications

Abstract

This paper details the development of low residual stress and low stress gradient unintentionally doped polycrystalline SiC (poly-SiC) thin films. The films were deposited in a large-volume, low-pressure chemical vapor deposition (LPCVD) furnace on 100 mm-diameter silicon (Si) wafers using dichlorosilane (SiH 2 Cl 2 ) and acetylene (C 2 H 2 ) as precursors. We found that the flow rate of SiH 2 Cl 2 could be used to control the residual film stress in the as-deposited films. Wafer curvature measurements for $2 m-thick films indicated that tensile stress ranging from 4 to 55 MPa across a 25 wafer boat had been achieved. A variety of micromachined structures including lateral resonant structures, stress pointers and cantilevers were fabricated for characterization of the deposited SiC films. The average Young's modulus was found to be 403 GPa. Residual stress measurements were consistent with those obtained using a wafer curvature technique. Interferometric measurements of cantilever beams indicated stress gradients with an upper bound of 52 MPa/m for $2 m-thick films with tensile stress less than 55 MPa.

Room Temperature Process for Chemical Vapor Deposition of Amorphous Silicon Carbide Thin Film Using Monomethylsilane Gas

“…Silicon carbide (SiC) is recognized as a suitable material for various applications, such as a carbon susceptor coating film used in a chemical vapor deposition reactor [1] and a functional material for a microelectromechanical system (MEMS) [2]. Although silicon carbide is robust even in a harsh environment and at high temperatures, one of the major problems of silicon carbide is its very high temperature required for chemical vapor deposition (CVD) [3,4].…”

Nanostructured carbon-based thin films : prediction and design

“…For these methods, the carbon sources, the presence of hydrogen during deposition, and the energy of the deposited species are determining factors for the structure and the properties of the films [37]. In addition, the incorporation of different p-elements, such as nitrogen [38][39][40][41][42], phosphorus [43][44][45][46][47], silicon [48,49], sulfur [50][51][52][53], fluorine [54][55][56][57][58], and chlorine [59,60], allows for further adjustment of the film's structure, expanding the range of possible properties and applications.…”

Micro-electro-mechanical-systems (MEMS) for assessing and monitoring civil infrastructures

“…3C-SiC is the only polytype that can be deposited on silicon substrate, which makes it the dominant polytype for MEMS sensor applications (Jiang and Cheung, 2009). Various micromachined structures can be designed using deposited polycrystalline 3C-SiC layers, such as lateral resonators and cantilevers (Fu et al ., 2011;Wright and Horsfall, 2007).…”