Optimization of chemical mechanical polishing of (010) β-Ga2O3
Abstract
Smooth (< 0.5 nm rms) and subsurface damage-free (010) β-Ga2O3 was achieved with low-pressure chemical mechanical polishing. An applied pressure of 1 kPa along with colloidal silica and poromeric polyurethane polishing pads rotating at 30 rpm was found to be the optimal polishing parameters for (010) β-Ga2O3. Using higher pressures typically employed in the current literature induced subsurface damage in the substrates. Diffuse scatter intensity of triple-axis x-ray rocking curves was used to determine the presence of subsurface lattice damage, which was quantified by measuring peak widths below the half maximum (i.e., FWXM where X < 0.5). The initially rough surfaces of (010) β-Ga2O3 substrates due to wafer slicing and grinding were lapped and polished. A 5 μm Al2O3 slurry followed by a 0.3 μm Al2O3 slurry was used as the primary lap material removal step. The material removal rates were ∼20 and ∼9 μm/h, respectively. Then, chemical mechanical polishing was performed using colloidal alumina followed by colloidal silica. The removal rates were ∼1.3 and ∼0.4 μm/h, respectively. Only colloidal silica showed the complete removal of subsurface damage. The final (020) β-Ga2O3 rocking curve FWHM was ∼13″ and FW(0.001)M was ∼120″, which matches the widths of commercially available pristine (010) β-Ga2O3. A final cleaning step using dilute bleach and dilute citric acid to remove residual silica slurry particles from the surface was demonstrated.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 01, 2023
- Source ID
- 10.1116/6.0002241
Entities
People
- Dorian P. Luccioni
- Kenny Huynh
- Lezli Matto
- Mark S. Goorsky
- Michael E Liao
Organizations
- Office of Naval Research
- University of California, Los Angeles