Extremely High-Rate Deposition of High-Quality Amorphous Silicon Carbide Films

利用常压等离子体化学气相沉积（CVD）技术，以极高的速率沉积了非晶态Si_<1-x>C_x（a-Si_<1-x>C_x: H）薄膜。薄膜是在含有He、H_2、SiH_4和CH_4的甚高频等离子体中，在常压下在Si（001）硅片上制备的。首先，利用透射电子显微镜（TEM）、俄歇电子能谱（AES）和红外吸收光谱（IR）研究了沉积速率和膜的结构、密度和组成随CH_4浓度的变化规律。结果表明，该方法的最大沉积速率为5Onm/s，比传统等离子体CVD技术快10倍以上，但沉积的薄膜具有稀疏的原子结构。为了改善a-Si_<1-x>C_x: H薄膜的结构，进行了进一步的研究。利用红外吸收光谱和AES研究了a-Si_<1-x>C_x:H薄膜的结构（C-H和Si-H键密度）和组成随VHF功率、CH_4/SiH_4比和衬底温度的变化规律。用扫描电镜观察了膜的表面形貌。结果表明，气相中产生的颗粒使膜的形貌恶化，并导致膜中氢原子的过量掺入。抑制气相颗粒形成和消除生长表面与C和Si原子结合的过量氢原子是促进Si-C网络形成的重要因素。作为。通过优化沉积参数，在衬底温度为550℃的条件下，可以制备出化学计量的a- sic:H薄膜。

Using the atmospheric pressure plasma chemical vapor deposition (CVD) technique, hydrogenated amorphous Si_<1-x>C_x(a-Si_<1-x>C_x : H) films deposited at extremely high rates. The films were prepared on Si(001) wafers at atmospheric pressure in a very high frequency (VHF) plasma of gas mixtures containing He, H_2, SiH_4 and CH_4. First, deposition rate and film properties (structure, density and composition) were studied by transmission electron microscope (TEM), Auger electron spectroscopy (AES) and infrared (IR) absorption spectroscopy as a function of CH_4 concentration. It was found that the maximum deposition rate was 5Onm/s, which was more than 10 times faster than that achieved by the conventional plasma CVD technique, although the deposited films had sparse atomic structures. In order to improve the structure of the a-Si_<1-x>C_x : H films, further investigations were performed. Structure (C-H and Si-H bond densities) and composition of the a-Si_<1-x>C_x:H films were studied as functions of VHF power, CH_4/SiH_4 ratio and the substrate temperature by IR absorption spectroscopy and AES. Surface morphology of the films was observed by scanning electron microscope (SEM). It was implied that particles generated in gas phase deteriorated the film morphology and caused excessive incorporation of hydrogen atoms in the film. Both suppressing particle formation in gas phase and elimination of excessive hydrogen atoms bonded to C and Si atoms at the film-growing surface were important factors to enhance Si-C network formation. As.a result of optimising the deposition parameters, a stoichiometric a-SiC:H film could be deposited at the substrate temperature of 550℃.