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

研制了一套半原位处理系统。它由STM系统、带有涡轮分子泵（TMP）（真空度低于10^ Torr）的CVD室<-7>、隔振器、用于CVD的Ta灯丝和气体入口系统以及使用测微头的衬底引导系统组成。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。由于它可以调整到1 μ m左右，STM观察相同的面积在纳米尺度上可以成功地进行。此外，我们研究了解理的高取向热解石墨（HOPG）作为衬底的金刚石薄膜的纳米加工。众所周知，可以容易地获得大的原子级平坦和惰性表面。我们尝试了用CH_4-H_2体系辅助CVD法沉积金刚石纳米结构的半原位观察。典型的实验条件如下：气体为CH_4 + H_2（H_2/CH_4=49.5sccm/0.5sccm），总压为50 Torr，Ta丝温度为1800 - 2300 K，衬底为室温HOPG，沉积时间为10秒。从沉积前后的STM图像可以观察到约10至100 nm的沉积物。大多数金刚石薄膜都是沿着HOPG衬底的自然台阶生长的，在更高的衬底温度和灯丝温度下，金刚石薄膜的成核过程正在进行中。此外，利用STM对金刚石薄膜进行表面改性，将有助于金刚石薄膜的纳米加工。

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.