Production of High‐Density Capacitively Coupled Plasma with RF Multi‐Hollow Cathode and/or High Secondary Electron Emission for DLC Film Preparation

Abstract

The effects of a hollow cathode discharge and secondary electron emission from a radio‐frequency‐biased electrode on the growing rate of diamond‐like carbon films were studied. The rate of deposition for amorphous hydrogenous carbon thin films of about 200 nm·min−1 was attained at a voltage of −700 V with radio‐frequency plasma using CH4 gas. Because of its non‐uniformity, the profile was improved by changing the hole arrangement. A radial roughness of the deposited films of about 35 nm, for a film thickness of about 1 µm, was obtained with the best arrangement.

Physics of High-Density Radio Frequency Capacitively Coupled Plasma with Various Electrodes and Its Applications

“…The effects of a multi-hollow cathode discharge and a high SEE are applied to capacitively coupled plasma to produce high-density plasma [25,26]. Figure 5(a) and (b) shows the experimental apparatus and construction of the multi-hollow electrode, respectively.…”

High-Density Radio-Frequency Plasma Sources Produced by Capacitive Discharge with Various Methods for Thin-Film Preparation

“…Recently, the effects of multihollow cathode discharge and high-secondary-electron emission in capacitively coupled discharge have been investigated so as to achieve the high-growth rate of diamond-like carbon (DLC) films (14) (15) . The experimental apparatus consists of a grounded vacuum vessel with 160 mm diameter and 500 mm length and two parallel plates with 80 mm diameter, as shown in Fig.…”

“…7. Various hollow-electrodes (15) emit secondary electrons from the plate and on which silicon wafer is set. The plate is called substrate electrode.…”

Plasma density enhancement in radio-frequency hollow electrode discharge

“…In addition to parallel-plate electrodes [17][18][19], hollow electrodes [20][21][22][23][24][25] are also frequently applied in RF and direct current (DC) discharges. With a hollow electrode, RF-CCPs can produce higher plasma density outside the cavity when a low frequency is utilized, which implies that plasma density enhancement effect exists in RF discharges with hollow electrodes [20][21][22][26][27][28]. Moreover, utilizing hollow electrodes with different shapes, uniform plasma density can be obtained and the film deposition quality can be improved [29][30][31].…”

“…Although previous investigations have shown that RF-CCPs with hollow electrodes can enhance the electron density outside the cavity, the mechanism of density enhancement is still unclear. Previous studies have also found that discharge conditions affect the magnitude of electron density outside the cavity [21,28,38,39]. For instance, electron density outside the cavity can be influenced by the pressure, magnetic field and electrode gap [28,38,40].…”