甲烷浓度对金刚石膜沉积质量的影响

Effect of methane concentration on quality of diamond film deposition

在10kW微波等离子化学气相沉积装置中,采用甲烷和氢气作为气源,在直径为50mm的P型(100)单晶硅片上进行了不同甲烷浓度条件下金刚石薄膜的制备研究.利用扫描电子显微镜和激光Raman光谱仪对所制备的金刚石膜进行表征.结果表明:较高的甲烷浓度(2%,体积分数)虽然可以加快金刚石膜生长速率,但离解反应气体的能量相对减弱,晶粒尺寸较小;此时原子氢刻蚀作用也会较弱,非金刚石相含量增加,残留的杂质越来越多,金刚石纯度不高,薄膜的质量较差.随着甲烷浓度的降低,金刚石膜(100)晶面充分显现,薄膜质量逐渐变好.然而过低的甲烷浓度(0.5%,体积分数)会导致有利于金刚石生长的含碳活性基团含量降低,使金刚石膜生长缓慢,晶粒尺寸难以长大.

In the microwave plasma chemical vapor deposition of 10 kW,the diamond films were synthesized from CH4 and H2 gas mixture on P-type （100） monocrystalline silicon of φ50 mm.The diamond films prepared under different concentration of methane were characterized by scanning electron microscopy and laser spectroscopy Raman.Results show that the higher methane concentration is propitious to accelerate growth rate,but it leads to insufficient dissociation energy and small grain size; meanwhile,the weaker corrasion effect of the hydrogen atoms results in low purity of diamond and poor quality of films;the quality of films is getting better as diamond film （100） plane appears fully with reducing methane concentration; however,the content of activated carbon group which is benefit to grow diamond films decreases if the methane concentration is too low（0.5％）,which makes the diamond film grow slowly and the grain size grow up difficultly.