Study on the Preparation of Diamond Film Substrates on AlN Ceramic and Their Performance in LED Packaging

At a Glance

Metadata	Details
Publication Date	2025-09-08
Journal	Micromachines
Authors	Shasha Wei, Yingrui Sui, Yunlong Shi, Junrong Chen, Tungalag Dong
Institutions	Jimei University
Analysis	Full AI Review Included

Technical Documentation & Analysis: Diamond Films for High-Power LED Thermal Management

This document analyzes the research paper “Study on the Preparation of Diamond Film Substrates on AlN Ceramic and Their Performance in LED Packaging” to highlight 6CCVD’s capabilities in supporting and advancing high-performance thermal management solutions using Microwave Plasma Chemical Vapor Deposition (MPCVD) diamond.

Executive Summary

The research successfully demonstrates that depositing a Polycrystalline Diamond (PCD) film onto an Aluminum Nitride (AlN) ceramic substrate significantly enhances heat dissipation for high-power Light-Emitting Diodes (LEDs).

Superior Thermal Performance: The AlN/Diamond composite substrate achieved a total thermal resistance of 3.9 K/W at 3 W power, significantly lower than bare AlN (7.8 K/W) and traditional aluminum (14.1 K/W).
Junction Temperature Reduction: The diamond film reduced the LED junction temperature (T_j) by 29.4% compared to the bare AlN substrate under 1.2 A current, proving its effectiveness under high-power conditions.
Optimal Growth Recipe: High-quality PCD films were achieved using MPCVD with optimized parameters: 4% methane concentration, 900 °C deposition temperature, and 0.5 sccm oxygen flow rate.
Material Quality: The optimized process yielded continuous, dense diamond films with high crystallinity, well-defined grain contours, and low non-diamond carbon content.
Process Reliability: The study validates the use of MPCVD for producing thick (531 µm) thermal-grade diamond films suitable for integration into complex electronic packaging via standard semiconductor processes (polishing, laser cutting, magnetron sputtering).

Technical Specifications

The following hard data points were extracted from the optimal growth conditions and performance testing results:

Parameter	Value	Unit	Context
Optimal Deposition Temperature	900	°C	For uniform grains and high crystallinity
Optimal Methane Concentration	4	%	Optimal balance of growth rate and quality
Optimal Oxygen Flow Rate	0.5	sccm	Suppresses non-diamond carbon phases
MPCVD Microwave Power	4600	W	Standard growth parameter
Sedimentary Pressure	155	Torr	Standard growth parameter
Achieved Film Thickness	531	µm	PCD film deposited on AlN substrate
AlN Substrate Dimensions	Ø20 x 0.8	mm	Substrate used for deposition
Final Thermal Resistance (R_th)	3.9	K/W	AlN/Diamond composite at 3 W power
T_j Reduction (vs. AlN)	29.4	%	Reduction at 1.2 A operating current
Optimal Surface Roughness (Ra)	163	nm	Measured at 4% CH₄, 900 °C
Theoretical Diamond Thermal Conductivity	>2000	W/m·K	Target thermal performance

Key Methodologies

The preparation and characterization of the AlN ceramic substrate diamond thin-film base involved the following critical steps:

Substrate Preparation: Ø20 mm x 0.8 mm AlN ceramic substrates were cleaned sequentially using hydrofluoric acid solution (to remove oxides), acetone, anhydrous ethanol, and deionized water.
Seeding: Substrates were immersed in a diamond powder suspension (W0.25 particle size) and ultrasonically treated for 30 min to enhance nucleation density.
MPCVD Growth: Diamond films were deposited using a 2.45 GHz microwave plasma system.
Parameter Optimization: Growth parameters were systematically varied to determine optimal conditions:
- Methane concentration (2% to 5%) was optimized for growth rate and defect density.
- Deposition temperature (700 °C to 950 °C) was optimized for grain morphology and crystalline orientation (preferential (111) growth).
- Oxygen flow rate (0 to 1.5 sccm) was optimized to suppress non-diamond carbon phases.
Post-Growth Processing: The diamond films underwent grinding and polishing, followed by laser cutting.
Metalization: A conductive metal layer was applied via magnetron sputtering and photolithography to enable electrical connection to the LED device.
Performance Testing: Packaged LED devices were tested for junction temperature (T_j) using infrared imaging and thermal resistance (R_th) calculation.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the high-quality MPCVD diamond materials and custom processing required to replicate and advance this research in high-power LED packaging and other thermal management applications.

Research Requirement	6CCVD Solution & Capability	Value Proposition for Engineers
Applicable Materials	PCD Thermal Grade Diamond: We supply high-purity Polycrystalline Diamond (PCD) films optimized for thermal conductivity (>1800 W/m·K).	Guaranteed material performance to meet or exceed the thermal dissipation targets of this study.
Custom Dimensions	Large-Area Scalability: While the paper used Ø20 mm substrates, 6CCVD offers PCD plates/wafers up to 125 mm in diameter.	Enables direct scaling of this technology for high-volume manufacturing of large LED arrays or power electronic modules.
Thickness Control	Precision Film Thickness: We provide PCD films from 0.1 µm up to 500 µm (matching the 531 µm film grown here), and custom substrates up to 10 mm thick.	Precise control over the thermal pathway length, optimizing cost and performance for specific device architectures.
Substrate Compatibility	Custom Heteroepitaxial Growth: 6CCVD has expertise in depositing diamond films on non-native substrates, including AlN, SiC, and refractory metals, ensuring high adhesion and quality.	Reliable integration of diamond layers onto customer-supplied or custom ceramic bases.
Metalization Requirements	In-House Metalization Services: We offer custom metal stacks (e.g., Ti/Pt/Au, as commonly used in LED packaging) via internal magnetron sputtering capability. Available metals include Au, Pt, Pd, Ti, W, and Cu.	Provides a fully integrated, ready-to-package substrate, minimizing external vendor complexity and interfacial contamination.
Surface Finish	Ultra-Precision Polishing: We achieve surface roughness (Ra) of < 5 nm on inch-size PCD wafers, significantly smoother than the 163 nm reported in the optimal sample.	Minimizes Interfacial Thermal Resistance (ITR) between the diamond film and the metal layer, crucial for maximizing heat transfer efficiency.
Logistics & Support	Global Shipping & Expert Consultation: We offer global shipping (DDU/DDP) and dedicated engineering support.	Seamless procurement and access to our in-house PhD team for material selection and process optimization for similar high-power thermal projects.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Aluminum nitride (AlN) ceramic materials have relatively low thermal conductivity and poor heat dissipation performance, and are increasingly unsuitable for high-power LED packaging. In this study, diamond films were deposited on AlN ceramic substrates by microwave plasma chemical vapor deposition (MPCVD). The effects of different process parameters on the crystal quality, surface morphology and crystal orientation of diamond films were studied, and the high thermal conductivity of diamond was used to enhance the heat dissipation ability of AlN ceramic substrates. Finally, the junction temperature and thermal resistance of LED devices packaged on AlN ceramic-diamond composite substrate, AlN ceramic substrate and aluminum substrate were tested. The experimental results show that compared with the traditional aluminum and AlN ceramic substrates, AlN ceramic-diamond composite substrates show excellent heat dissipation performance, especially under high-power conditions.

Tech Support

Original Source

DOI: https://doi.org/10.3390/mi16091029

References

2024 - Synthesis and characterization of a high-strength alumina ceramic reinforced by AlN-Al2O3 coating [Crossref]
2024 - Limiting the lattice oxygen impurities to obtain high thermal conductivity aluminum nitride ceramics [Crossref]
2024 - Effects of grain boundary phase distributions on mechanical characteristics of the high thermal conductivity AlN ceramics [Crossref]
2024 - Effect of AlN content on microstructure and properties of SiAlON ceramics prepared via vat photopolymerization [Crossref]
2022 - Monometallic and bimetallic SiC(O) ceramic with Ni, Co and/or Fe nanoparticles for catalytic applications [Crossref]
2022 - Addition Effects of MgO on Structure and Physical Properties in Bi-2212 Ceramics [Crossref]