Plasma etching of CVD diamond films using an ECR-type oxygen source

Abstract

The etching characteristics of CVD (chemical vapour deposition) diamond films processed with an ECR (electron cyclotron resonance) oxygen plasma are investigated. The etching rate increases linearly with increasing microwave power in the range from 100 to 300 W. For any value of microwave power, the etching rate first increases with increasing gas flow rate, reaches a maximum rate at a gas flow rate of 3 sccm (standard cc min-1), and then decreases gradually with further increase in the gas flow rate. The etching rate increases linearly with increasing negative bias voltage in the range from 0 to -600 V. The etching rate for 100 and 300 W of microwave power and a negative bias of -600 V is 17 and three times greater, respectively, than that for 0 V bias. The surface roughness increases with increasing microwave power in the range from 0 to 300 W. The surface roughness before etching is eight times greater than that obtained after plasma etching with 300 W of microwave power. The Raman spectrum of a CVD diamond film after oxygen plasma etching for 1 h shows not only a diamond (sp3 bonding) peak at 1333 cm-1, but also a broad non-diamond (sp2 bonding) peak around 1500 cm-1. However, as the etching time increases, the broad non-diamond peak around 1500 cm-1 disappears.