Development of low temperatuer diamond synthesis apparatus using high magnetic field assisted dc plasma

为了在较低衬底温度下用化学气相沉积法合成金刚石，研制了一种新型潘宁离子源装置。该装置由一个具有两个阴极和一个阳极的直流放电等离子体发生器和一个产生最大磁场为3 T的超导磁体组成。我们证实所研制的超导磁体可以产生稳定的3 T磁场，当外加1 T磁场时，可以在10^Torr的低压下产生等离子体。用甲烷气体合成了碳<-3>膜用于评估所开发的设备的性能。以硅为衬底材料，甲烷与氢气的流量比为5%，反应室压力为0.67Pa，成膜时间为12 h。在沉积碳膜的过程中，在放电区施加了1 T的磁场。结果，在温度为35 ℃的衬底表面上沉积了暗蓝色的绝缘薄膜。通过拉曼光谱对该膜进行了评估，发现该膜是含有碳原子的金刚石结构的类金刚石碳。虽然这表明用所研制的装置合成金刚石是可能的，但薄膜很可能是通过气相中甲烷气体的反应和电极材料的溅射沉积的，发现如何消除这种污染是下一个问题。

In order to synthesize diamond at low substrate temperature by chemical vapor deposition, a newly type of apparatus has been developed using Penning ion source. This apparatus consists of a plasma genertor by dc discharge which has two cathode and a anode, and a superconducting magnet that generates the maximum magnetic field of 3 T.We have confirmed that the developed superconducting magnet can generates stable magnetic field of 3 T and plasma can be generated at low pressure of 10^<-3> Torr when a magnetic field of 1 T is impressed.Carbon films have been synthesized using methane gas for estimating the performance of the apparatus developed. Silicon has been used for substrate material, and the flow ratio of methane gas to hydrogen gas, the pressure in the reaction chamber and duration of film synthesis have been set at 5%, 0.67 Pa and 12h, respectively. During deposition of a carbon film, the magnetic field of 1 T has been impressed at discharge area. As a result, a dark-bule colored, insulated thin film has been deposited on the substrate surface of which temperature has been 35ﾟC.This film has been estimated by Raman spectroscopy and the film is found to be diamond-like carbon that contains diamond structure of carbon atoms. Although this indicates the possibility of diamond synthesis with the apparatus developed, the films are likely to be deposited by the reaction of methane gas in gas phase and the sputtering of electrode materials, it is found that how to eleminate this contamination is the next problem.