Removal and characterization of focused-ion-beam-induced damaged layer on single crystal diamond surface and application to multiple depth patterning

In this research, we investigated both the etching characteristics of the non-diamond phase induced by focused ion beam (FIB) irradiation and the patterning method of shallow multiple depth structures. FIB irradiation on the diamond surface induces a non-diamond phase, and this area can be selectively etched by heating in air. The dependence of the shape on the FIB and heating conditions was investigated. Process temperatures equal to or lower than 600 °C were effective for structure fabrication in terms of the fine shape of the structure. The removal depth can be controlled by varying the ion fluence and ion energy. The process temperature and heating time were important factors for determining the depth range and etch rate. The shape of the structure was affected by the morphology of the FIB-induced non-diamond phase, and the maximum etching depth was dependent on the defect density induced by FIB irradiation. Concave multiple-depth structures with depths of several tens of nanometres were fabricated based on these results, indicating the possible use of this method for shallow multiple depth patterning on diamond surfaces.