Microcrystalline diamond film evaluation by spectroscopic optical coherence tomography
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2022-09-30 |
| Journal | Photonics Letters of Poland |
| Authors | Paulina StrÄ kowska, Marcin R. StrÄ kowski |
| Institutions | GdaĆsk University of Technology |
| Citations | 2 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: MPCVD Diamond for Advanced Metrology
Section titled âTechnical Documentation & Analysis: MPCVD Diamond for Advanced MetrologyâReference Paper: Microcrystalline diamond film evaluation by spectroscopic optical coherence tomography (Photonics Letters of Poland, Vol. 14 (3), 50-52, 2022)
Executive Summary
Section titled âExecutive SummaryâThis research validates Spectroscopic Optical Coherence Tomography (Sc-OCT) as a powerful, non-invasive method for evaluating submicrometer thickness variations in thin Microcrystalline Diamond (MCD) films. 6CCVD leverages its expertise in MPCVD growth to supply the high-uniformity diamond materials required for replicating and advancing this metrology.
- Core Achievement: Successful evaluation of MCD film thickness changes in the submicrometer range (below standard OCT resolution) using Sc-OCT enhanced by time-frequency analysis.
- Material Focus: Microcrystalline Diamond (MCD) thin films (average 1.5 ”m thickness) deposited via MWPA-CVD onto Ti6Al4V alloy substrates, targeting medical implant applications.
- Structural Findings: The deposited layer exhibited a heterogeneous structure, primarily composed of TiC and 1-2 ”m diamond crystallites surrounded by amorphous carbon.
- Methodology: The films were grown using a standard MPCVD recipe (1:99 CH4:H2 ratio, 700 °C TS) following nanodiamond suspension nucleation.
- Industrial Relevance: This technique is critical for quality control and development of complex, multi-layered diamond coatings used in biomedical, semiconductor, and advanced photonics devices.
- 6CCVD Value: We provide the necessary high-uniformity Polycrystalline Diamond (PCD) and Single Crystal Diamond (SCD) films, with custom thickness control (0.1 ”m to 500 ”m) and precision polishing (Ra < 5 nm), essential for high-resolution optical metrology.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the MWPA-CVD deposition recipe and the Sc-OCT system used for evaluation.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Average Film Thickness | 1.5 | ”m | Microcrystalline Diamond (MCD) layer |
| Substrate Temperature (TS) | 700 | °C | MWPA-CVD deposition temperature |
| Gas Ratio (CH4:H2) | 1:99 | Ratio | CVD precursor mixture |
| Process Pressure | 50 | Torr | CVD chamber environment |
| Total Gas Flow Rate | 300 | sccm | CVD process |
| Microwave Power (PMW) | 1.3 | kW | Plasma excitation power |
| Deposition Time | 180 | min | MCD layer growth duration |
| Diamond Crystallite Size | 1-2 | ”m | Observed via SEM |
| Substrate Material | Ti6Al4V (ASTM 136) | Alloy | Cylindrical specimens (16mm D x 2mm H) |
| OCT Central Wavelength | 1290 | nm | Sc-OCT system feature |
| OCT Wavelength Range | 140 | nm | Sc-OCT system feature |
| OCT Axial Resolution | 12 | ”m | In air (Standard OCT limitation) |
| Thickness Change Resolution | Submicrometer | Range | Achieved using Spectroscopic OCT analysis |
Key Methodologies
Section titled âKey MethodologiesâThe MCD films were synthesized using a standard Microwave Plasma Assisted Chemical Vapor Deposition (MWPA-CVD) process following specific nucleation steps.
- Substrate Preparation: Cylindrical Ti6Al4V specimens were mechanically polished (1-3 ”m diamond suspension) and chemically cleaned via sonication in deionized water, acetone, and ethanol.
- Nanodiamond Nucleation: Samples were immersed or sonicated for 1 hour in a nanodiamond suspension (0.5% mass concentration in DMSO) to promote high-density nucleation sites.
- CVD Growth: Deposition was performed in an Astex AX6500 MWPA-CVD system using a methane and hydrogen mixture (1:99 ratio) at 50 Torr pressure and 300 sccm total flow.
- Plasma Excitation: Microwave power was maintained at 1.3 kW, achieving a substrate temperature of 700 °C over a 180-minute deposition time.
- Material Characterization: The resulting MCD layer was analyzed for morphology (SEM, AFM) and phase composition (Raman Spectroscopy), confirming the presence of TiC and amorphous carbon alongside diamond crystallites.
- Optical Evaluation: Film thickness uniformity was mapped using a customized Spectroscopic OCT (Sc-OCT) system (1290 nm central wavelength) by monitoring the shift of local minima in the back-referenced light spectra.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research highlights the critical need for highly uniform, thin-film diamond materials on complex substrates for advanced optical metrology and biomedical applications. 6CCVD is uniquely positioned to supply the required materials and customization services.
| Research Requirement | 6CCVD Solution & Capability | Engineering Advantage |
|---|---|---|
| Microcrystalline Diamond (MCD) Film | Optical Grade Polycrystalline Diamond (PCD) | Our MPCVD process delivers highly uniform PCD wafers up to 125mm, ensuring consistent material properties necessary for reliable optical measurements. |
| Precise Thickness Control (1.5 ”m) | Thin Film Capability (0.1 ”m to 500 ”m) | We guarantee precise thickness control, enabling researchers to replicate the exact 1.5 ”m film or explore thinner/thicker films with submicrometer accuracy. |
| Custom Substrate Deposition (Ti6Al4V) | Custom Dimensions & Substrate Handling | 6CCVD routinely handles non-standard engineering materials, including titanium alloys, ceramics, and silicon, allowing for direct deposition onto customer-supplied implant prototypes or custom wafers. |
| High Surface Quality for OCT | Precision Polishing Services | For optical applications like Sc-OCT, surface scattering is critical. We offer polishing down to Ra < 5 nm for inch-size PCD, minimizing noise and maximizing signal coherence. |
| Heterogeneous Structure (TiC/C/Diamond) | Custom Doping and Growth Recipes | Our in-house PhD team can adjust gas ratios (e.g., CH4:H2) and temperature profiles to control the resulting phase composition, allowing for tailored growth of composite diamond/carbide layers. |
| Future Device Integration | Internal Metalization Services | We offer integrated metalization (Au, Pt, Ti, Pd, W, Cu) for immediate device prototyping, essential if the diamond film is to be used as an electrode or sensor component in biomedical implants. |
Applicable Materials
Section titled âApplicable MaterialsâTo replicate or extend this research, 6CCVD recommends the following materials:
- Optical Grade Polycrystalline Diamond (PCD): Ideal for replicating the high-quality MCD structure used in this study, offering excellent mechanical and optical uniformity across large areas (up to 125mm).
- High Purity Single Crystal Diamond (SCD): For extending the research to applications requiring superior optical transparency, lower scattering, and higher thermal conductivity, available in thicknesses from 0.1 ”m to 500 ”m.
Customization Potential
Section titled âCustomization PotentialâThe research utilized a small, custom-shaped Ti6Al4V substrate (16mm diameter). 6CCVD specializes in providing diamond films on unique geometries and materials. We offer:
- Custom Substrate Processing: Deposition onto customer-provided medical-grade alloys (like Ti6Al4V) or ceramics.
- Laser Cutting and Shaping: Precise shaping of diamond plates to match specific device or implant dimensions.
- Integrated Metalization: Providing the necessary contact layers (e.g., Ti/Pt/Au stacks) required for integrating the diamond film into functional electronic or electrochemical devices.
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team provides expert consultation on material selection, growth recipe optimization, and post-processing. We can assist researchers and engineers working on similar biomedical implant coatings and advanced optical metrology projects to ensure the diamond material meets the exact structural and optical requirements for high-resolution Sc-OCT analysis.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. We offer global shipping (DDU default, DDP available) to ensure rapid delivery of research-grade materials worldwide.
View Original Abstract
This study has focused on the microcrystalline diamond film (MCD) thickness evaluation. For this purpose, optical coherence tomography (OCT) enhanced by spectroscopic analysis has been used as a method of choice. The average thickness of the tested layer was about 1.5 ”m, which is below the standard 2-point OCT resolution. In this case, the usefulness of the spectroscopic analysis was confirmed for the evaluation of the thickness changes in the submicrometer range. Full Text: PDF ReferencesM.D. Drory, J.W. Hutchinson, âDiamond Coating of Titanium Alloysâ, Science, 263 (1994). CrossRef J. Wang, J. Zhou, H.Y. Long, Y.N. Xie, X.W. Zhang, H. Luo, Z.J. Deng, Q. Wei, Z.M. Yu, J. Zhang, Z.G. Tang, âTribological, anti-corrosive properties and biocompatibility of the micro- and nano-crystalline diamond coated Ti6Al4Vâ, Surf. Coat. Technol., 258 (2014). CrossRef P.A. Nistor, P.W. May, F. Tamagnini, A.D. Randall, M.A. Caldwell, âLong-term culture of pluripotent stem-cell-derived human neurons on diamond - A substrate for neurodegeneration research and therapyâ, Biomaterials, 61 (2015). CrossRef C.A. Love, R.B. Cook, T.J. Harvey, P.A. Dearnley, R.J.K. Wood, âDiamond like carbon coatings for potential application in biological implantsâa reviewâ, Tribol. Int., 63 (2013). CrossRef P. StrÄ kowska, R. Beutner, M. Gnyba, A. Zielinski, D. Scharnweber, âElectrochemically assisted deposition of hydroxyapatite on Ti6Al4V substrates covered by CVD diamond films â Coating characterization and first cell biological resultsâ, Materials Science and Engineering: C, 59 (2016). CrossRef T.S. Ho, P. Yeh, C.C. Tsai, K.Y. Hsu, S.L. Huang., âSpectroscopic measurement of absorptive thin films by Spectral-Domain Optical Coherence Tomographyâ, Opt. Express 22, 5 (2014). CrossRef N. Bosschaart, T.G. van Leeuwen, M.C.G. Aalders, D.J. Faber, âQuantitative comparison of analysis methods for spectroscopic optical coherence tomographyâ, Biomedical Opt. Express 4, 11 (2013). CrossRef F.E Robles, C. Wilson, G. Grant, A. Wax, âMolecular imaging true-colour spectroscopic optical coherence tomographyâ, Nat. Photonics 5, 12 (2011). CrossRef A.F. Fercher, W. Drexler, C.K. Hitzenberger, T. Lasser, âOptical coherence tomography - principles and applicationsâ, Rep. Prog. Phys. 66, 239 (2003). CrossRef A.M. KamiĆska, M.R. StrÄ kowski, J. PluciĆski, âSpectroscopic Optical Coherence Tomography for Thin Layer and Foil Measurementsâ, Sensors 20, 19, (2020). CrossRef M. Kraszewski, M. StrÄ kowski, J. PluciĆski, B.B. Kosmowski, âSpectral measurement of birefringence using particle swarm optimization analysisâ, Appl. Opt. 54, 1 (2015). CrossRef