Diamondlike carbon film deposition on a polycarbonate-tube inner wall using a cylindrical electrode with radio frequency glow discharge plasma

摘要

Radio frequency (rf) plasma chemical vapor deposition (CVD) process is very useful for film deposition. However, common rf plasma CVD techniques using planar electrodes make it difficult to apply to three-dimensional insulator structures. In this study, to deposit diamondlike carbon (DLC) films on a polycarbonate-tube inner wall (φ 11 mm, length 100 mm), we have developed the cylindrical electrode plasma process. This process could be adapted to cylindrical substrates such as polymeric tubes. In investigating the availability of this process, under helium (He) gas pressures (50, 100, and 150 Pa), the plasma states of the rf power at 30 W were measured using a double-probe method. The He plasma was generated bright as a stable, hollow cathode discharge inside the polycarbonate tube. As a result, the cylindrical electrode process was expected to have applications for cylindrical materials such as polymeric tubes. In actual deposition of DLC film (CH_4 gas at 10 Pa, rf power at 30 W, and deposition time at 10 min), the DLC film was deposited completely on the polycarbonate-tube inner wall. The distribution of the film thickness was 300-350 nm, and the structures of the DLC film were uniform. It was observed that the DLC film was deposited uniformly. The cylindrical electrode process is expected to apply to three-dimensional insulator structures such as polymeric tubes.