Experimental study of inductively coupled plasma etching of patterned single crystal diamonds

In this study, the inductively coupled plasma (ICP) etching process for patterning single-crystal diamond was experimentally investigated using O₂/Ar as the etching gas. The influence of various etching parameters on the process was analyzed via laser confocal microscopy. Taking etching rate and surface roughness as the primary evaluation metrics, the optimal etching parameters were determined as follows: an O₂/Ar gas flow ratio of 50/50 sccm, an ICP power of 600 W, a bias (RF) power of 120 W, and a chamber pressure of 20 mTorr.The experimental results indicate that the etching rate increases significantly with higher RF power and ICP power. Additionally, the etching rate exhibits a gradual increase with a higher oxygen content in the O₂/Ar ratio, while the influence of chamber pressure on the etching rate follows an increasing-then-decreasing trend. Moreover, the O₂/Ar gas flow ratio and chamber pressure have minimal impact on surface roughness, whereas increasing ICP and RF power leads to a pronounced rise in surface roughness, particularly under high-power conditions. Finally, by calculating the ratio of diamond etching depth to mask depletion thickness, the etch selectivity of this process was determined to be 1:46.