Low-damage grinding process of gallium oxide based on cerium oxide

The ultra-wide bandgap semiconductor material β -Ga 2 O 3 exhibits potential in power devices and UV detectors. However, its hard and brittle characteristics and cleavage properties result in severe damage during processing. This study used cerium oxide (CeO 2 ) in an alkaline solution to grind β -Ga 2 O 3 . The (010) β -Ga 2 O 3 exhibited less surface and subsurface damage (SSD), although it encountered significant SSD during processing. SEM of (010) β -Ga 2 O 3 cross sections showed that the SSD caused by CeO 2 is plastic slip. Median cracks with a depth of less than 1 μm were only observed in some areas. In contrast, diamond produces microcrack defects in the subsurface up to a depth of 2 μm. When grinding with CeO 2 , bonds of Ga-O-Ce are formed with active oxygen on the surface of β -Ga 2 O 3 . The material is removed by combining mechanical and “chemical tooth” models. A characteristic peak of this structure appears at 530.01 eV in the O 1s spectrum of the sample's XPS . The mechanical action of CeO 2 deforms the surface structure, removing surface damage through ductile domain removal. After 3 h of CMP , the FWHM of the rocking curve for the CeO 2 ground sample decreased from 668 ± 20 ″ to 61 ± 5 ". In contrast, the diamond ground sample only reduced from 643 ± 23 ″ to 210 ± 8 ". This decreased rate for the CeO 2 sample was significantly higher than for the diamond. The method eliminates the damage by combining actions, reducing new damage. It has research value and economic benefits for optimizing the process and obtaining damage-free β -Ga 2 O 3 substrates. • Cerium oxide abrasive in an alkaline solution for grinding β -Ga 2 O 3 substrates offers low cost and low damage. • CeO 2 's hardness resembles β -Ga 2 O 3 's, so plastic slip dominates material removal. Only <1μm median cracks exist in some areas. • Prepared β -Ga 2 O 3 reaches 61 arcsecs FWHM after brief chemical mechanical polishing, with a higher decreased rate than diamond. • The chemical removal mechanism in grinding (010) β -Ga 2 O 3 by cerium oxide abrasives is explained.