Abstract:

Growing a boron film on the inner wall of a vacuum chamber is a critical wall treatment technology for a Tokamak device. In this paper, the spherical glow discharge vacuum chamber was built by ourselves. The boron film was successfully prepared on the wall of the vacuum chamber by plasma chemical vapor deposition with diborane as boron source. The results of SEM and adhesion test show that the boron film has compact structure, complete coverage and good adhesion, and the adhesion of the film is more than 240 N/m. The effects of the concentration of diborane, pressure, current density and temperature on the growth of boron films were systematically studied. The optimum preparation conditions of room temperature, 1%—2% ethoborane, 5—10 Pa pressure and 4.7—6.2 μA/cm² current density are obtained. The suppression effect of boron film on impurities in the vacuum chamber was explored via a residual gas analyzer (RGA). The results show that the partial pressures of the residual gases H₂O, CO₂, CO and O₂ after boronization are lower 200%, 400%, 200% and 10% than that before boronization, respectively. The suppression mechanism was deduced by analyzing the partial pressure of residual gases and the composition of boron film obtained by X-ray photoelectron spectroscopy (XPS).

Key words: boron film, growth law, preparation process, suppression performance

摘要：

在真空腔室内壁生长硼膜是托卡马克装置至关重要的壁处理技术。自主搭建了球形辉光放电真空室，选用乙硼烷为硼源，采用等离子体化学气相沉积(PECVD)法在真空室内壁成功制备出硼膜。扫描电镜和结合力测试表明：制备出的硼膜结构致密，覆盖完整，结合力良好，膜层的结合力>240 N/m。同时系统研究了乙硼烷浓度、气压、电流密度和温度对硼膜生长的影响规律，并得出了室温条件下，乙硼烷浓度1%~2%，气压在5~10 Pa，电流密度4.7~6.2 μA/cm²的最佳制备工艺。通过残余气体分析仪(RGA)检测腔室内残余气体压力，进而研究硼膜对杂质的抑制性能。结果表明：硼化后腔室内残余气体H₂O、CO₂、CO和O₂的分压明显降低，比硼化前分别降低了200%，400%，200%和10%。结合腔室残余气体的分压结果和硼膜成分的X射线光电子能谱分析(XPS)，推测出硼膜对杂质的抑制机理。

关键词: 硼膜, 生长规律, 制备工艺, 抑制性能