Development of nano-scale processing with the tunneling electrons from a scanning tunneling microscope (STM) under atmospheric or reduced pressure

研制了半原位加工系统。它由STM系统、带有涡轮分子泵（TMP）的CVD室（真空低于10^<-7> Torr）、隔振器、用于CVD的ta灯丝和气体入口系统以及使用微米头的基板导向系统组成。STM系统和CVD系统由AIN-BN热障隔开。衬底导向系统使HOPG衬底在STM系统和CVD系统之间来回移动。由于可以调整到1mum左右，因此可以在纳米尺度上成功地进行相同区域的STM观测。此外，我们研究了劈裂的高取向热解石墨（HOPG）作为纳米金刚石薄膜加工的衬底。众所周知，可以很容易地获得大的原子平面和惰性表面。更幸运的是，金刚石薄膜可以在HOPG衬底上合成。我们尝试了用CH_4-H_2体系的丝辅助CVD沉积纳米尺度结构的半原位观察。典型实验条件为：气体：CH_4 + H_2(H_2/CH_4=49.5sccm/0.5sccm)；总压力50Torr；ta丝温度：1800 - 2300K；衬底，室温下的HOPG；沉积时间，10秒。从沉积前后的STM图像中可以观察到约10 ~ 100nm的沉积。它们大多是沿着HOPG衬底的自然台阶沉积的。进一步的研究在更高的衬底和灯丝温度，其中金刚石的成核预期，目前正在进行中。此外，利用STM的表面修饰，金刚石薄膜的纳米加工将得到发展。

A semi in-situ processing system was developed. It consists of a STM system, CVD chamber with a turbo molecular pump (TMP)(vacuumed below 10^<-7> Torr), a vibration isolator, Ta-filament and gas inlet system for CVD, and a substrate guiding system using a micrometer head. The STM system and the CVD system are separated by an AIN-BN thermal barrier. The substrate guiding system makes HOPG substrates go back and forth between the STM system and the CVD system. Since it can be adjusted to about 1mum, STM observations of same areas on nanometer scale can be performed successfully.Moreover, we examined the cleaved highly oriented pyrolytic graphite (HOPG) as substrates for nano-processing of diamond films. It is well-known that the large atomically flat and inert surface can be easily obtained. What was more fortunate, diamond films can be synthesized on a HOPG substrate.We tried semi in-situ observations of nanometer scale structures deposited by filamentassisted CVD of CH_4-H_2 system. Typical experimental conditions are as follows: gases, CH_4 + H_2(H_2/CH_4=49.5sccm/0.5sccm); total pressure, 50Torr; Ta-filament temperature, 1800 - 2300K; substrate, HOPG at room temperature; deposition time, 10sec. From the STM images before and after deposition, deposits about 10 to 100nm could be observed. Most of them were deposited along the natural steps of a HOPG substrate.Further researches at higher substrate and filament temperatures, where the nucleation of diamond is expected, are now in progress. In addition, using the surface modifications with using a STM, nano-processing of diamond films will have been developed.