热丝CVD沉积金刚石薄膜时的等离子体空间分布研究

采用热丝化学气相沉积(chemical vapor deposition，CVD)的方法，以丙酮为碳源生长金刚石薄膜时，利用等离子体发射光谱对生长过程中的等离子体空间分布进行了在线诊断。采用SEM，Raman光谱分别对沉积金刚石膜表面、断面的形貌和质量进行表征。光谱分析表明，对于线性阵列布丝情况下，中心区域与边缘区域的基团分布存在差异，中心区温度高，裂解能力强，基团强度高于两边，但中心区域基团特征峰强度的变化比等离子球平缓的多;距离热丝越远，热辐射减小，从丙酮分子中裂解出CH和CO等基团以及由原子H激发的H_β与H_α等强度降低，反而使得复合生成的C₂基团增加。SEM测试结果表明，当丝基间距为4.5，5.5，6.5 mm时，所沉积的金刚石薄膜表面由致密规则晶面向混乱转变，且单位时间内的生长速率也依次降低，此外，Raman光谱表明随着纵向间距的加大，金刚石薄膜的质量随之降低。这与诊断结果中CH和CO强度的降低，C₂基团强度增加及基团C₂/H_α比强度下降相吻合。

The Effect of Plasma Spatially Resolved During Diamond Film Deposited with HFCVD

Optical emission spectroscopy (OES)was used to detect the plasma distribution during the depositing process of dia-mond films with hot filament chemical vapor deposition (HFCVD)method using acetone as carbon source.The surface and cross section of deposited diamond films were characterized by scanning electron microscopy (SEM)and their quality was tested with Raman spectroscopy.OES results showed that the intensity of active species near the center is higher than that in marginal area in the case of linear array of hot filament.It is because of the higher temperature and stronger cracking ability near the filament. The variety of the characteristic peak intensity in central region is more gently than that of the plasma ball.Thermal radiation de-creased when the distance from the hot filament increases,which results in less CH,CO groups cracked from acetone,lower in-tensity of Hα,Hβ excited by hydrogen and higher concentration of C2 group produced by reaction.SEM and Raman results showed that the quality of deposited diamond films deteriorated when the distance between hot filament and substrate varies from 4.5,5.5 to 6.5 mm,which matches well with OES results.