Plasma intensification in 2 MHz RF glow discharge in carbon film plasma sputtering deposition by means of a hollow cathode

Abstract

A hollow cathode has been one of the methods to intensify the plasma in the etching or ashing process. This work examined a number of technologies in the intensification of a 2 MHz RF glow discharge plasma to deposit carbon film by means of the hollow cathode. Three types of the cathode configurations, which were cylindrical, rectangular and a cylindrical-rectangular combination, were tested to get an optimum condition for the carbon deposition. Both carbon target and substrate were fixed inside the hollow cathode. The plasma was characterized by means of optical emission spectroscopy (OES) at the range of 200 nm – 1000 nm. The results showed that the combination where the rectangular hollow was placed inside the cylindrical one, produced the most intense glow. Ion density and electron temperature in the plasma were determined by a calculation based on the atomic data related to the specific electronic transitions of the ions. The density of ions was very high in the centre area of the rectangular hollow producing complex reactions. On the other hand, the high density of the ions decreases the electron temperature. The energy of the ions was difficult to be predicted since the spectrum showed the existence of a large number of ion states. Observations on the resulted deposit on the surface of quartz substrate suggest that the intensification needs to be further investigated related to the effectiveness of sputtering and deposition process.