Recent Progress of Diamond Semiconductor Devices
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2022-06-04 |
| Journal | Journal of the Japan Society for Precision Engineering |
| Authors | Makoto KASU, Seong-Woo KIM |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: 2-Inch Diamond Wafer Growth for Power Devices
Section titled âTechnical Documentation & Analysis: 2-Inch Diamond Wafer Growth for Power DevicesâThis document analyzes the research paper âRecent Progress of Diamond Semiconductor Devicesâ2-Inch Wafer Growth and Power Device Fabricationâ to provide relevant technical specifications and highlight how 6CCVDâs advanced MPCVD diamond materials and processing capabilities can support and extend this world-leading research in diamond power electronics.
Executive Summary
Section titled âExecutive SummaryâThis research successfully demonstrates the fabrication of the worldâs largest and highest-quality heteroepitaxial diamond wafers for high-power applications, achieving record-breaking device performance.
- Scale and Quality: Achieved 2-inch diameter (001) diamond wafers using MPCVD heteroepitaxy on tilted (1120) Sapphire/Ir substrates.
- Record Crystal Quality: Demonstrated world-best crystal quality for heteroepitaxial diamond, achieving a Threading Dislocation Density (TDD) of 1.4 x 107 cm-2.
- Advanced Growth Technique: Utilized step-flow growth on tilted substrates (up to 7°) to mitigate residual stress and eliminate the need for complex microneedle structures, enabling spontaneous self-separation of the diamond film.
- High Breakdown Voltage: Fabricated a Diamond FET achieving a record off-state breakdown voltage (Vdsoff) of -2608 V with Al2O3 passivation.
- World Record Power Performance: The resulting FET demonstrated a Baliga Figure of Merit (BFOM) of 344.7 MW/cm2, confirming diamondâs superiority for next-generation power electronics.
- Material Thickness: Final free-standing diamond films were processed to 500-600 ”m thickness.
Technical Specifications
Section titled âTechnical SpecificationsâThe following table summarizes the key material properties and device performance metrics achieved in the research.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Wafer Diameter | 2 | inch | Heteroepitaxial Diamond (001) |
| SCD Bandgap (EG) | 5.47 | eV | Reference Material Property |
| Breakdown Field (EBR) | >10 | MV/cm | Reference Material Property |
| Thermal Conductivity (λ) | 22 | W/cmK | Reference Material Property |
| Threading Dislocation Density (TDD) | 1.4 x 107 | cm-2 | World Best for Heteroepitaxial Diamond |
| XRC FWHM (004) | 98.35 | arcsec | Crystal quality using step-flow growth |
| XRC FWHM (311) | 175.3 | arcsec | Crystal quality using step-flow growth |
| Substrate Tilt Angle | 0 to 7 | ° | Used for stress mitigation and step-flow |
| Final Diamond Thickness | 500-600 | ”m | Free-standing film thickness |
| Maximum Drain Current (IDmax) | -288 | mA/mm | Diamond FET (VGS = -7 V) |
| Specific On-Resistance (Ron,spec) | 19.74 | mΩcm2 | Diamond FET |
| Off-State Breakdown Voltage (Vdsoff) | -2608 | V | With Al2O3 passivation |
| Baliga Figure of Merit (BFOM) | 344.7 | MW/cm2 | World Record for Diamond FET |
Key Methodologies
Section titled âKey MethodologiesâThe 2-inch heteroepitaxial diamond growth and subsequent FET fabrication relied on precise control over substrate preparation and MPCVD parameters.
- Substrate Preparation: (1120) A-plane Sapphire substrates were used, followed by the sputtering deposition of an Ir buffer layer.
- Nucleation (BEN): Bias-Enhanced Nucleation (BEN) was performed on the Ir buffer layer by negatively biasing the substrate and positively biasing the plasma, accelerating ionized methyl (CH3) groups into the Ir surface to promote diamond nucleation.
- Stress Mitigation (Step-Flow): Heteroepitaxial growth was performed on Sapphire substrates tilted 0° to 7° from the (1120) plane. This step-flow growth technique was critical for relaxing residual stress and achieving high crystal quality without the use of microneedles.
- MPCVD Growth: Microwave Plasma Chemical Vapor Deposition (MPCVD) was used with CH4 and H2 gases.
- Self-Separation: The difference in thermal expansion coefficients between the diamond film and the Ir/Sapphire stack allowed the diamond layer to spontaneously separate from the substrate upon cooling, yielding a free-standing wafer.
- Device Fabrication: The free-standing (001) diamond was polished (Ra < 1nm implied by âatomic level flatnessâ) and used to fabricate a FET structure involving:
- NO2 p-type doping for the channel.
- Au Source/Drain electrodes.
- Al2O3 gate dielectric and passivation layer (100 nm thick).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is uniquely positioned to supply the high-quality diamond materials and custom processing required to replicate, optimize, and scale the results demonstrated in this research for commercial power electronics applications.
Applicable Materials
Section titled âApplicable MaterialsâTo achieve the world-record performance demonstrated in this paper, engineers require diamond material with exceptional purity, low defect density, and precise orientation.
- Single Crystal Diamond (SCD) Substrates:
- Application: Ideal for homoepitaxial growth of active device layers, offering significantly lower TDD (typically < 105 cm-2) compared to the 1.4 x 107 cm-2 achieved in heteroepitaxy. This is essential for maximizing breakdown voltage and current density.
- 6CCVD Offering: High-purity, electronic-grade SCD plates, available in standard (001) orientation, ready for subsequent device layer growth.
- Boron-Doped Diamond (BDD):
- Application: While the paper used NO2 surface doping, BDD is the standard for stable, high-concentration p-type layers, ohmic contacts, or conductive substrates in diamond power devices.
- 6CCVD Offering: Custom BDD layers (SCD or PCD) with precise doping concentrations for optimized channel or contact layers.
Customization Potential
Section titled âCustomization PotentialâThe research highlights the need for large-area wafers and complex metalization stacks, both of which are core competencies of 6CCVD.
| Requirement from Paper | 6CCVD Capability | Benefit to Customer |
|---|---|---|
| 2-inch Diameter Wafer | PCD Wafers up to 125mm (5 inches) | Enables immediate scaling beyond the 2-inch limit for commercial production and larger device layouts. |
| 500-600 ”m Thickness | SCD/PCD Thickness up to 500 ”m | We provide free-standing wafers matching the required thickness for robust device handling and thermal management. |
| Atomic-Level Flatness (Ra < 1nm) | Precision Polishing (Ra < 1nm for SCD) | Ensures optimal surface morphology for subsequent epitaxial growth, metalization, and gate dielectric deposition (e.g., Al2O3). |
| Au Electrodes & Al2O3 Passivation | Custom Metalization Services | We offer in-house deposition of Au, Pt, Ti, W, and Cu, allowing researchers to integrate ohmic contacts and bond pads directly onto the diamond substrate, streamlining the fabrication process. |
Engineering Support
Section titled âEngineering SupportâThe successful fabrication of a world-record diamond FET requires deep expertise in material science and device physics.
- In-House PhD Team: 6CCVDâs engineering staff, including PhD material scientists, specializes in optimizing MPCVD growth recipes and material selection for high-power and high-frequency applications.
- Application Focus: We provide consultation on material selection (SCD vs. PCD), orientation, and doping profiles necessary to extend this research into commercial Diamond Power Electronics and RF/Microwave Devices.
- Global Logistics: We ensure reliable, global shipping (DDU default, DDP available) of sensitive, high-value diamond wafers, supporting international research collaborations.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.