Fabrication of multi-layer CVD-SiC films with different microstructures by manipulating the input gas ratio

Abstract

From the last several years, SiC tube has been proposed as a furnace component in the integrated circuit (IC) industry [1]. Reaction-bonded silicon carbide (RBSC) produced by infiltration of the Si melt has been applied to the reaction tube since it has little shrinkage after sintering [2]. RBSC as a reaction tube, however, has two problems at elevated temperatures. One is that residual Si on the surface of RBSC can react with deposits (SiO2, Si3N4, polycrystalline silicon) during the IC process because RBSC is actually composed of roughly 85% SiC and 15% residual Si [2]. The other is that the high purity condition of the furnace is hampered by the diffusion of impurities in RBSC. To solve these problems, pure SiC films are coated on the inside wall of the RBSC tube as a protective and diffusion barrier layer. SiC also has a excellent properties in its chemical behavior such as oxidation, corrosion and creep resistance at high temperatures as well as in its mechanical behavior [3–5]. SiC films grown by chemical vapor deposition (CVD) have the advantages of good uniformity [6, 7], high purity, and a stoichiometric composition. Multi-layer CVD-SiC films with different microstructures can be more effective as a diffusion barrier than mono layer films due to the increased diffusion pass of impurities. The input gas ratio (dilute ratio, α = PH2/PMTS = QH2/QMTS) can be used as a deposition parameter to fabricate multi-layer SiC films with different microstructures, because it offers more productivity and cost advantages than the deposition temperature [8]. We have previously reported that the microstructure of mono layer SiC films is changed by manipulating the input gas ratio at the deposition temperature of 1250 ◦C [9]. In this work, the fabrication of multi-layer SiC films using the input gas ratio as a deposition parameter was investigated. The experiments were performed in a hot-wall horizontal reactor with a concentric double-tube structure. Methyltrichlorosilane (MTS, CH3SiCl3) was chosen as a source precursor and hydrogen was used as both carrier and dilutant gas. RBSC was used as a substrate,