Oxidation Etching Mechanism of Boron-Doped CVD Polycrystalline Diamond Films
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2025-06-01 |
| Journal | Journal of The Surface Finishing Society of Japan |
| Authors | Haisheng Song, H. Kanda, Osamu Fukunaga, Hitoshi Sumiya, Sadao Takeuchi |
| Institutions | National Institute for Materials Science, Nippon Institute of Technology |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Boron-Doped Diamond Oxidation Resistance
Section titled âTechnical Documentation & Analysis: Boron-Doped Diamond Oxidation ResistanceâThis document analyzes the research paper, âOxidation Etching Mechanism of Boron-Doped CVD Polycrystalline Diamond Films,â focusing on the material science implications and connecting the findings directly to 6CCVDâs advanced MPCVD diamond capabilities.
Executive Summary
Section titled âExecutive SummaryâThe research confirms the superior thermal and chemical stability of Boron-Doped Polycrystalline Diamond (BDD) films, a critical finding for high-temperature and high-wear applications.
- Core Achievement: Demonstrated that BDD films exhibit significantly higher oxidation resistance compared to Non-Doped Diamond (NDD) when exposed to air at 825 °C.
- Mechanism Identified: The enhanced resistance is attributed to the formation of Boron Trioxide ($\text{B}{2}\text{O}{3}$) on the diamond surface during heating.
- Protective Layer: The $\text{B}{2}\text{O}{3}$ layer acts as a protective film, suppressing the oxidation and subsequent etching of the underlying diamond structure.
- Material Performance: NDD films showed severe etching across grain boundaries, while BDD films (3000 ppm B/C) maintained structural integrity with only minor etching on self-formed facets.
- Analytical Confirmation: Auger Electron Spectroscopy (AES) and X-ray Photoelectron Spectroscopy (XPS) confirmed the presence of B-O bonding (192 eV peak) on the heated BDD surface, validating the $\text{B}{2}\text{O}{3}$ mechanism.
- Application Relevance: This research is vital for engineers designing high-temperature tools, chemical reactors, and high-power electronic devices requiring robust thermal stability in oxygenated environments.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the synthesis and testing parameters used in the study.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Synthesis Method | Hot Filament CVD (HFCVD) | N/A | Used for BDD film growth. |
| Film Thickness (PCD) | 200 | ”m | Approximate synthesized thickness. |
| Average Grain Size | 30 | ”m | Approximate size of polycrystalline grains. |
| Synthesis Pressure | 6.66 | kPa | CVD chamber pressure. |
| Hydrogen Flow Rate | 150 | cc/min | Carrier gas flow. |
| Methane Concentration ($\text{CH}_{4}$) | 1 | % | Relative to Hydrogen flow. |
| Boron Concentration (Gas Phase) | 3000 | ppm | Relative to Carbon source ($\text{CH}_{4}$). |
| Oxidation Test Temperature | 825 | °C | Peak temperature held for 1 hour. |
| Heating Rate | 50 | °C/min | Rate of temperature increase in air. |
| Protective Layer Identified | $\text{B}{2}\text{O}{3}$ | N/A | Boron Trioxide, formed on the surface after heating. |
| XPS B-O Peak Location | 192 | eV | Confirmed $\text{B}{2}\text{O}{3}$ or $\text{H}{3}\text{BO}{3}$ bonding after heating. |
Key Methodologies
Section titled âKey MethodologiesâThe experiment focused on synthesizing high-quality BDD films and subjecting them to controlled thermal oxidation in an air atmosphere.
- Substrate Preparation: Commercial cemented carbide cutting tips (K10 equivalent) were mirror-polished and seeded (nucleated) to facilitate diamond growth.
- HFCVD Synthesis: Polycrystalline diamond (PCD) films were grown using a gas mixture of $\text{CH}{4}$ (1% concentration) and $\text{H}{2}$ (150 cc/min) at a pressure of 6.66 kPa.
- Boron Doping: Trimethylboron ($\text{B}(\text{CH}{3}){3}$) was introduced as the boron source, diluted in $\text{H}_{2}$ to achieve a 3000 ppm B/C ratio in the gas phase. Total synthesis time was 480 hours to achieve the target 200 ”m thickness.
- Thermal Oxidation Test: Free-standing diamond fragments (2-4 mm) were heated in an electric furnace in an air atmosphere. The temperature was ramped at 50 °C/min until 825 °C was reached, followed by a 1-hour hold time before slow cooling.
- Post-Test Analysis: Surface morphology changes (etching) were observed using Scanning Electron Microscopy (SEM). Elemental composition and chemical state analysis were performed using Auger Electron Spectroscopy (AES) and X-ray Photoelectron Spectroscopy (XPS) to confirm the presence and bonding state of boron and oxygen.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD specializes in high-purity MPCVD diamond, offering superior material quality and customization necessary to replicate, optimize, and scale the findings of this oxidation resistance research.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate or extend this research, 6CCVD recommends the following materials, leveraging the superior control of MPCVD over HFCVD:
- Heavy Boron Doped PCD Wafers: Ideal for high-wear, high-temperature applications. 6CCVD offers precise control over boron concentration, allowing researchers to test the oxidation mechanism across a range of doping levels (e.g., 1000 ppm to 10000 ppm B/C).
- Non-Doped Polycrystalline Diamond (PCD): For baseline comparison studies (replicating the NDD film used in the paper), 6CCVD provides high-purity PCD with controlled grain sizes.
- Boron Doped Single Crystal Diamond (SCD): For applications requiring extreme thermal management and oxidation resistance without grain boundaries, 6CCVD can provide BDD SCD films up to 500 ”m thick.
Customization Potential
Section titled âCustomization PotentialâThe study utilized specific dimensions and high thickness, which aligns perfectly with 6CCVDâs core capabilities:
| Research Requirement | 6CCVD Capability & Solution | Value Proposition |
|---|---|---|
| Thickness: High thickness (200 ”m used) | PCD Thickness up to 500 ”m. We routinely grow robust PCD films up to half a millimeter thick, exceeding the requirements of this study. | Provides extended material lifetime and structural integrity for industrial tools and high-power devices. |
| Dimensions: Custom shapes/fragments | Custom Wafers up to 125mm. We provide full inch-size wafers or precision laser-cut parts to exact specifications, eliminating the need to manually cleave fragments. | Facilitates large-scale device fabrication and ensures dimensional accuracy for integration. |
| Surface Finish: High-performance required | Ultra-Smooth Polishing. We offer PCD polishing down to Ra < 5nm for inch-size wafers. | Minimizes surface defects that can act as nucleation sites for oxidation, potentially further enhancing the $\text{B}{2}\text{O}{3}$ protective effect. |
| Metalization: Device integration | In-House Custom Metalization. We offer deposition of Au, Pt, Pd, Ti, W, and Cu for creating high-temperature contacts or heat spreading layers. | Enables direct integration of BDD films into high-power electronic or sensor packages requiring stable contacts above 800 °C. |
Engineering Support
Section titled âEngineering SupportâThe successful implementation of BDD for high-temperature applications requires precise material engineering. 6CCVDâs in-house PhD team specializes in optimizing diamond growth parameters (MPCVD pressure, gas chemistry, and doping concentration) to achieve specific electrical and thermal properties. We can assist researchers and engineers in selecting the optimal doping level and grain structure for similar high-temperature chemical wear resistance projects.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. We offer global shipping (DDU default, DDP available) for rapid delivery of your custom diamond solutions.