STRUCTURE OF POLYCRYSTALLINE DIAMOND COATINGS DEPOSITED BY СVD METHOD IN THE PLASMA OF GLOW DISCHARGE WITH THE USE OF PULSE POWER SUPPLY
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2021-04-07 |
| Authors | Konstantin Koshevoy, Yu.Ya. Volkov, V.E. Strel’nitskij, E.N. Reshetnyak |
| Institutions | Kharkiv Institute of Physics and Technology |
| Citations | 2 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Pulsed CVD Polycrystalline Diamond
Section titled “Technical Documentation & Analysis: Pulsed CVD Polycrystalline Diamond”Reference Paper: Structure of Polycrystalline Diamond Coatings Deposited by CVD Method in the Plasma of Glow Discharge with the Use of Pulse Power Supply
6CCVD Internal Project Focus: High-Quality, Texture-Controlled Polycrystalline Diamond (PCD) for Advanced Engineering Applications.
Executive Summary
Section titled “Executive Summary”This research successfully demonstrates the synthesis of high-quality polycrystalline diamond (PCD) films using a novel approach: Pulsed DC Glow Discharge Chemical Vapor Deposition (CVD) stabilized by a magnetic field. The findings are highly relevant for engineers requiring precise control over diamond microstructure.
- Enhanced Material Quality: The use of pulsed power and grounded substrate holders resulted in PCD coatings with superior perfection, achieving lattice parameters (0.3565-0.3566 nm) nearly identical to natural diamond (0.35667 nm).
- Microstructure Control: The study established a clear correlation between synthesis parameters (CH$_{4}$ partial pressure and substrate temperature) and the resulting crystallographic texture.
- Texture Engineering Achieved: Specific texture zones were mapped, allowing for the intentional growth of films dominated by <100>, <111>, or <110> orientations, critical for optimizing mechanical or electronic performance.
- Crystallite Size Optimization: Coherent Scattering Region (CSR) size was successfully tuned from 38 nm up to 240 nm, indicating control over grain perfection and internal defect density.
- Scalable Methodology: The technique utilizes a modified glow discharge CVD, offering a potentially cost-effective and energy-efficient alternative to complex microwave plasma systems for producing high-performance PCD films (20-40 µm thick).
Technical Specifications
Section titled “Technical Specifications”The following hard data points were extracted from the research, detailing the synthesis conditions and resulting material properties.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Material Type | Polycrystalline Diamond (PCD) | N/A | Cubic space group Fm3m |
| Film Thickness | 20 to 40 | µm | Achieved over 8-9 hours deposition time |
| Substrate Temperature (Ts) | 955 to 1160 | °C | Measured using optical pyrometer |
| Total Pressure (Ptotal) | 16 x 103 and 21 x 103 | Pa | Two primary pressure settings investigated |
| Methane Content (CH4) | 1.5 to 3.0 | % | In H2-CH4 gas mixture |
| Partial CH4 Pressure (PCH4) | 3.2 x 102 to 4.8 x 102 | Pa | Critical parameter for texture control |
| Average Power (Pavg) | 2.5 to 3.0 | kW | Delivered by 50 kHz pulsed power supply |
| Lattice Parameter (a) | 0.3565 to 0.3566 | nm | Indicating high purity and crystallinity |
| CSR Size Range | 38 to 240 | nm | Coherent Scattering Region size (measure of crystal perfection) |
| Crystal Morphology | 5 to 20 | µm | Well-defined faceting observed |
| Predominant Texture Axes | <100>, <111>, <110> | N/A | Controlled by Ts and PCH4 |
Key Methodologies
Section titled “Key Methodologies”The experiment focused on optimizing the CVD process by implementing a pulsed power supply and grounding the substrate holder to improve diamond quality.
- Substrate Preparation: Monocrystalline Silicon (111) plates (7.0 x 7.0 x 0.5 mm) were used. The surface was mechanically pre-treated using diamond powder (ACM 2/3) to ensure high nucleation density.
- CVD Setup: Deposition was performed in a DC glow discharge reactor stabilized by a transverse magnetic field, utilizing a combined disc cathode (Ø 115 mm) and a grounded substrate holder (Ø 52 mm).
- Plasma Activation: A commercial pulsed power supply (Tru Plasma Bios 4018) was used, operating at 50 kHz frequency and a duty cycle of 1.1, delivering 2.5-3.0 kW average power.
- Gas Phase Control: The working gas was a mixture of H2 and CH4. The CH4 content was varied from 1.5% to 3.0%, corresponding to partial pressures of 3.2 x 102 Pa to 4.8 x 102 Pa.
- Temperature Control: Substrate temperature was precisely controlled and monitored between 955 °C and 1160 °C using an optical pyrometer.
- Structural Analysis: X-ray diffraction (XRD) was used to determine phase composition, calculate the lattice parameter, and quantify the CSR size using the Selyakov-Scherrer formula. Texture coefficients (Tc) were calculated to map crystallographic orientation.
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”This research validates the critical role of precise process control (pulsed power, temperature, and gas composition) in engineering the microstructure of PCD films. 6CCVD is uniquely positioned to supply the materials and customization required to replicate and advance this work for industrial and scientific applications.
Applicable Materials for Replication and Extension
Section titled “Applicable Materials for Replication and Extension”The high-quality, high-crystallinity PCD films synthesized in this study are directly analogous to 6CCVD’s standard Polycrystalline Diamond (PCD) offerings.
| 6CCVD Material Recommendation | Specification Match | Application Relevance |
|---|---|---|
| High-Purity PCD Wafers | Matches the high crystallinity and purity (near-natural lattice parameter) achieved in the study. | Ideal for thermal management, high-frequency electronics, and tribological coatings. |
| Custom Thickness PCD | The 20-40 µm thickness range is standard. 6CCVD offers PCD films from 0.1 µm up to 500 µm. | Allows researchers to scale thickness for specific mechanical or optical requirements. |
| Texture-Engineered PCD | 6CCVD’s MPCVD expertise allows for the intentional growth of specific textures (<100>, <111>) for optimized properties. | Essential for applications requiring anisotropic properties, such as enhanced heat spreading or specific mechanical wear resistance. |
Customization Potential for Advanced Research
Section titled “Customization Potential for Advanced Research”6CCVD’s in-house capabilities exceed the requirements of the base research, enabling immediate transition to device integration and large-scale production.
- Large Area Deposition: While the paper used small 7x7 mm substrates, 6CCVD offers PCD plates and wafers up to 125 mm in diameter, facilitating industrial scaling and the production of inch-size components.
- Precision Polishing: The resulting PCD films are suitable for optical or electronic applications. 6CCVD offers ultra-smooth polishing services, achieving roughness (Ra) of < 5 nm on inch-size PCD wafers, significantly reducing scattering losses and improving interface quality.
- Custom Substrate Handling: 6CCVD can accommodate various substrate materials beyond Si (111), including sapphire, ceramics, and refractory metals, crucial for integrating diamond into complex device stacks.
- Integrated Metalization Services: For researchers moving from material synthesis to device fabrication (e.g., sensors, electrodes, or heat sinks), 6CCVD provides in-house metalization using Au, Pt, Pd, Ti, W, and Cu, ensuring robust adhesion and electrical contact.
Engineering Support
Section titled “Engineering Support”The precise control over CSR size and texture demonstrated in this paper is vital for optimizing diamond performance in extreme environments. 6CCVD’s in-house PhD team specializes in correlating MPCVD parameters with resulting microstructure.
We offer comprehensive engineering support to assist clients in selecting the optimal PCD material specifications (thickness, grain size, and texture) for similar high-performance coating and electronic device projects, ensuring maximum material perfection and functional yield.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
The structure of CVD carbon coatings synthesized in a hydrogen-methane mixture in the plasma of a glow discharge stabilized by a magnetic field using a pulsed power supply was studied by X-ray diffraction analysis and optical microscopy. The range of deposition parameters is determined, which ensure formation of polycrystalline diamond coatings. The coatings consist of diamond crystals with a clearly defined cut and the crystal lattice parameter close to the tabular value for natural diamond. The influence of the methane partial pressure in the gas mixture and the substrate temperature on the size and predominant orientation of diamond crystals in the coatings was determined. It is established that the use of the pulse mode and grounding of the substrate holder helps to improve the quality of diamond coatings.