等离子体增强磁控溅射沉积碳化硅薄膜的化学结构与成膜机理

以CH4和Ar为工作气体,单晶硅为溅射靶,通过微波电子回旋共振(MW-ECR)等离子体增强非平衡磁控溅射方法在不同的CH4流量和沉积温度下制备了a-Si1-xCx∶H薄膜.利用傅里叶变换红外(FT-IR)光谱,X光电子能谱(XPS)和纳米硬度仪等表征方法研究不同沉积参数下薄膜的化学结构、化学配比和硬度的变化.结果表明:室温(25℃)下随CH4流量由5cm·3min-1增加到45cm3·min-1(标准状态)时,薄膜中Si—CH2键,C—H键含量逐渐增加,Si—H键变化不明显;膜中C原子百分比由28%增至76%,Si原子百分比由62%降至19%.当CH4流量为15cm3·min-1时,随沉积温度的升高,薄膜中Si和C原子百分比含量分别为52%和43%,且基本保持不变;膜中Si—H键和C—H键转化为Si—C键,薄膜的显微硬度显著提高,在沉积温度为600℃时达到29.7GPa.根据分析结果,提出了室温和高温下a-Si1-xCx:H薄膜生长模型.

Chemical Structure and Growth Mechanism of a-SixC1-x:H Films Prepared by Plasma Enhanced Magnetron Sputtering

Hydrogenated amorphous silicon carbide (a-Si_1-xC_x:H) films were prepared by microwave electron cyclotron resonance (MW-ECR) plasma enhanced unbalance magnetron sputtering with a silicon target and CH₄ as Si and C sources, respectively. The influence of CH₄ flow rate and the deposition temperature on the chemical structure, stoichiometry, and hardness were investigated by Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and nano-indentation. The results indicated that, as the CH4 flow rate increased from 5 to 45 cm³·min^-1 (standard state), the amount of Si—CH₂ groups and C—H groups increased constantly, but the number of Si—H groups did not change. The atomic concentration of C increases from 28% to 76% while Si decreases from 62% to 19%. The amount of Si—H and C—H groups in the deposited films decreases dramatically while the Si—C bonds and the hardness of the resultant films increase with an increase in deposition temperature at a constant CH4 flow rate. The atomic concentrations of Si and C remain almost constant at about 52% and 43%, respectively. The hardness of the deposited films with a constant CH₄ flow rate of 15 cm³·min^-1 increases to 29.7 GPa at a deposition temperature of 600 ℃. We propose a growth mechanism for the a-Si_1-xC_x:H films at room temperature (25 ℃) and at high temperature based on the characterization results.