Simulation and Preparation of 2 in. Mosaic Single Crystal Diamond Process via MPCVD

Although the Microwave Plasma Chemical Vapor Deposition (MPCVD) method used for diamond growth has been studied for several decades, single crystal diamond as a semiconductor material substrate still faces the challenge of being unable to simultaneously achieve a high growth rate and high crystal quality. This study presents a combined simulation and experimental approach for the fabrication of 2 in. mosaic single crystal diamond using the MPCVD method. A multiphysics model incorporating electromagnetic, plasma, and heat transfer modules was developed to analyze the distributions of temperature, electron density, electric field, and reactive species during diamond growth. Based on simulation insights, a novel molybdenum substrate holder with circumferential grooves was designed to achieve a uniform temperature distribution, limiting lateral temperature variation to within 20 K across the substrate surface. The simulation predicted a peak growth rate of 13.6 μm/h at the center and an average rate of 12.2 μm/h over the central 1 in. region area, consistent with experimental observations. A total of 39 single crystal diamond substrates were arranged in a mosaic pattern and subjected to a multistep MPCVD growth process, followed by laser edge removal and mechanical polishing. High-resolution X-ray diffraction and Raman mapping confirmed high crystalline quality, with full width at half-maximum(FWHM) values of 128.10–169.50 arcsec in XRD and 2.43–2.70 cm–1 in Raman spectra. The homoepitaxial regions exhibited superior crystal quality compared to lateral-epitaxial junctions, which exhibited mild stress concentration. This work establishes a scalable and quality-controllable pathway for producing large-area single crystal diamond wafers suitable for high-performance semiconductor devices.