高取向金刚石薄膜的制备

Preparation of High Oriented Diamond Films

目的研究不同甲烷体积分数、不同氮气流量分别对金刚石(111)面、(100)面生长的影响,实现在最佳工艺下制备高取向金刚石薄膜。方法采用微波等离子体增强化学气相沉积法制备高取向(111)面、(100)面金刚石薄膜,实验前一组(1~#—3~#)以CH_4/H_2为气源,后一组(4~#—5~#)以CH_4/H_2/N_2为气源,通过采用SEM、XRD分析不同甲烷体积分数下(111)面和不同氮气流量下(100)面的生长形貌、晶粒尺寸以及金刚石晶面特征峰强弱,同时还使用Raman测试两组分别改变甲烷体积分数、氮气流量工艺下金刚石特征峰、石墨峰的变化趋势。结果前一组随着甲烷体积分数的增加,金刚石(111)面逐渐清晰可见,低甲烷体积分数为2%时,H等离子体对金刚石表面刻蚀严重,形成少量表面粗糙的(111)面,当甲烷体积分数升到4.5%时,(111)面生长非常均匀,金刚石质量较高,继续提高甲烷体积分数,薄膜中非金刚石的含量增加,金刚石质量下降。后一组随着氮气流量的增加,金刚石(100)面的生长非常整齐平滑,在氮气流量为5 cm^3/min时,(100)面比较粗糙,由于有含氮基团的加入,其生长速率加快,进一步升高氮气流量到10 cm^3/min时,含氮基团的择优生长促进(100)面占据整个界面,同时削弱了其他晶面的生长。结论前一组甲烷体积分数为4.5%时,(111)面占据整个生长面,生长非常均匀,同时XRD测试金刚石(111)面特征峰也达到最强。后一组氮气流量为10 cm^3/min时,(100)面表面光洁度和平整度达到最佳。

The work aims to study the effects of different volume fractions of methane and nitrogen flow rate on diamond（111） and（100） planes, so as to prepare high oriented diamond films under optimal conditions. High oriented diamond films with（111） and（100） planes were prepared by using microwave plasma enhanced chemical vapor phase deposition（MPECVD） method. The previous group（1#—3#） took CH4/H2 as air source before experiment and the latter group（4#—5#）took CH4/H2/N2 gas as air source after experiment. Growth morphology, grain size and crystalline diamond surface characteristic peak intensity of（111） plane at different methane volume fractions and（100） plane at different nitrogen flow rates were analyzed by using SEM and XRD. Meanwhile, Raman test was conducted to change variation trend of diamond characteristic peaks and graphitic peaks at different methane volume fractions and nitrogen flow process. With the increase of methane volume fractions, the diamond（111） plane becomes visible in the former group When the low volume of methane concentration was 2%, the diamond surface was seriously etched by H plasma, little rough（111） plane was formed. When the methane volume fraction amounted to 4.5%,（111） plane growth was very uniform and the diamond was of high quality. As the methane volume fraction was further increased, non-diamond content of the film increased while diamond quality declined. For the latter group, as the nitrogen flow rate increased, diamond（100） plane growth was very smooth and tidy. At a low nitrogen flow rate of 5 cm3/min,（100） plane was relatively rough and the growth rate was accelerated since the added nitrogen containing groups were included. As the nitrogen flow rate was further increased to 10 cm3/min, the whole（100） plane was promoted to occupy the entire interface and growth of other crystal planes were weakened as a result of preferred growth of nitrogenous groups. For the previous group, the（111） plane occupies the entire growth plane with uniform growth and the characteristic peak of diamond（111） plane under XRD test amouts to the maximum as well when the methane volume fraction is 4.5%. For the latter group, surface smoothness and evenness are the best at the nitrogen flow rate of 10 cm3/min.