纳米金刚石薄膜掺硼的工艺研究
发布时间：2018-09-18 18:17
【摘要】：纳米金刚石(Nano-crystalline Diamond,NCD)薄膜既拥有传统微米金刚石薄膜的优良性能,又具有晶粒细小、表面平整、膜层较薄等特性,极大地拓宽了金刚石膜的应用领域。本文首先利用微波等离子体化学气相沉积(Microwave Plasma enhanced Chemical Vapor Deposition,MPCVD)法制备高平整度的NCD薄膜,然后以其作为本征层,在其上进行NCD薄膜的生长掺硼研究,通过对反应气压、微波功率、碳源浓度和沉积时间等工艺参数的研究,探讨了NCD薄膜掺硼的微观机理。在制备高平整度NCD薄膜的研究中发现:降低反应气压可以提高NCD薄膜的形核率和二次形核率,有利于沉积表面更为平滑的NCD薄膜;当沉积时间较短时,NCD膜层较薄,难以完全覆盖硅衬底上的划痕,当沉积时间太长时,晶粒的生长模式会逐渐向柱状转变,形成微米级的金刚石晶粒;高的CH4浓度可提高等离子体中含碳基团的浓度,并降低原子H的相对浓度,降低其对非金刚石相的刻蚀速率,提高金刚石的形核率和二次形核率,沉积出晶粒尺寸和表面粗糙度都比较小的NCD薄膜。通过以上研究,得到了10kW-MPCVD装置上制备高平整度NCD薄膜的较好工艺为微波功率3.5kW、沉积时间4-6h、反应气压2.5kPa、碳源浓度6%,制备出了NCD薄膜晶粒尺寸约为30nm,表面粗糙度低于20nm。在NCD薄膜的生长掺硼研究中发现:随着基片温度的升高,掺硼结束后NCD薄膜的表面粗糙度和晶粒尺寸都明显增大,在600℃到750℃的范围内,金刚石的晶粒尺寸由55nm增大到80nm;硼烷浓度与掺硼时间对薄膜表面形貌的影响与基片温度的影响趋势相似。随着掺杂过程中基片温度的增加,掺杂后薄膜的表面电阻率也随之变小,在750℃到850℃的温度范围内,其下降趋势尤为显著;反应气体中硼烷浓度对薄膜表面性能的影响与基片温度的影响相似,但随着硼烷浓度的增加,薄膜的表面电阻率会达到一个饱和值,该值一般在250~200??□范围内。此外,随着掺杂时间的延长,掺硼后NCD薄膜的表面电阻会首先快速降低,之后保持不变。为了获得表面平整、表面电阻较低的掺硼NCD薄膜,较好的工艺参数为:掺杂温度700℃,乙硼烷浓度200ppm、掺杂时间15min。
[Abstract]:Nanocrystalline diamond (Nano-crystalline Diamond,NCD) thin films not only have the excellent properties of traditional micron diamond films, but also have the characteristics of fine grain, flat surface and thin film layer, which greatly broadens the application field of diamond films. In this paper, NCD thin films with high smoothness were prepared by microwave plasma chemical vapor deposition (Microwave Plasma enhanced Chemical Vapor Deposition,MPCVD) method. Then boron doped NCD thin films were grown on the substrate by microwave plasma chemical vapor deposition (Microwave Plasma enhanced Chemical Vapor Deposition,MPCVD) method. The microcosmic mechanism of boron doping in NCD thin films was investigated by studying the technological parameters such as carbon source concentration and deposition time. It is found that the reduction of reaction pressure can increase the nucleation rate and the secondary nucleation rate of NCD thin films, which is beneficial to the deposition of smoother NCD films on the surface, and the thin films can be deposited when the deposition time is short. It is difficult to completely cover the scratches on silicon substrates. When the deposition time is too long, the grain growth pattern will gradually change to columnar, forming micron diamond grains, and high CH4 concentration can increase the concentration of carbon-containing groups in plasma. The NCD thin films with small grain size and surface roughness are deposited by decreasing the relative concentration of atomic H, decreasing the etching rate of the non-diamond phase, increasing the nucleation rate and the secondary nucleation rate of the diamond. Through the above research, we have obtained that the better technology for preparing NCD thin films with high smoothness on 10kW-MPCVD device is microwave power 3.5 kW, deposition time 4-6 h, reaction pressure 2.5 KPA, carbon source concentration 6. The grain size of NCD thin films is about 30 nm and the surface roughness is less than 20 nm. It is found that the surface roughness and grain size of NCD films increase with the increase of substrate temperature, and the surface roughness and grain size of NCD films increase from 600 鈩，
本文编号：2248725
[Abstract]:Nanocrystalline diamond (Nano-crystalline Diamond,NCD) thin films not only have the excellent properties of traditional micron diamond films, but also have the characteristics of fine grain, flat surface and thin film layer, which greatly broadens the application field of diamond films. In this paper, NCD thin films with high smoothness were prepared by microwave plasma chemical vapor deposition (Microwave Plasma enhanced Chemical Vapor Deposition,MPCVD) method. Then boron doped NCD thin films were grown on the substrate by microwave plasma chemical vapor deposition (Microwave Plasma enhanced Chemical Vapor Deposition,MPCVD) method. The microcosmic mechanism of boron doping in NCD thin films was investigated by studying the technological parameters such as carbon source concentration and deposition time. It is found that the reduction of reaction pressure can increase the nucleation rate and the secondary nucleation rate of NCD thin films, which is beneficial to the deposition of smoother NCD films on the surface, and the thin films can be deposited when the deposition time is short. It is difficult to completely cover the scratches on silicon substrates. When the deposition time is too long, the grain growth pattern will gradually change to columnar, forming micron diamond grains, and high CH4 concentration can increase the concentration of carbon-containing groups in plasma. The NCD thin films with small grain size and surface roughness are deposited by decreasing the relative concentration of atomic H, decreasing the etching rate of the non-diamond phase, increasing the nucleation rate and the secondary nucleation rate of the diamond. Through the above research, we have obtained that the better technology for preparing NCD thin films with high smoothness on 10kW-MPCVD device is microwave power 3.5 kW, deposition time 4-6 h, reaction pressure 2.5 KPA, carbon source concentration 6. The grain size of NCD thin films is about 30 nm and the surface roughness is less than 20 nm. It is found that the surface roughness and grain size of NCD films increase with the increase of substrate temperature, and the surface roughness and grain size of NCD films increase from 600 鈩，
本文编号：2248725
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