Abstract

With the power consumption of AI computing chips breaking the kilowatt level, traditional copper and aluminum heat dissipation materials have approached their physical limits. Featuring an ultra-high thermal conductivity of 2200–2600 W/(m·K) and a thermal expansion coefficient well-matched with silicon, diamond has become a revolutionary material for next-generation packaging and heat dissipation. In April 2026, a Japanese enterprise conquered the preparation technology of 2-inch diamond substrates and planned mass production within the year; a Shenzhen research team reduced the LED junction temperature by a record-breaking 72.8 °C through interface optimization. These two breakthroughs mark the transition of diamond packaging heat dissipation from laboratory research to industrialization, providing critical thermal management support for cutting-edge fields such as third-generation semiconductors, lasers, and quantum computing.

I. The Heat Dissipation Dilemma: Kilowatt-Level Chips Call for a Material Revolution

In 2026, the power consumption of a single NVIDIA Blackwell architecture GPU exceeds 1500W; the thermal design power (TDP) of AMD Instinct MI400 series AI accelerators reaches 1800W; and the packaging power consumption of Intel Falcon Shores XPU approaches 2000W. As chip power consumption climbs at an annual rate of 15–20%, traditional heat dissipation solutions face three major bottlenecks:

Thermal Conductivity Ceiling: The thermal conductivity of pure copper is approximately 400 W/(m·K). Even optimized via nanostructure design such as carbon nanotube doping and graphene coating, it can only be raised to 500–600 W/(m·K), insufficient to cope with ultra-high heat flux density of 500–1000 W/cm².

Thermal Expansion Mismatch: The coefficient of thermal expansion (CTE) of copper is about 17×10⁻⁶/°C, while that of silicon chips is merely 3×10⁻⁶/°C. Under drastic temperature differences, interfacial thermal stress causes chip warpage and solder joint cracking, leading to a sharp decline in reliability.

Weight and Space Constraints: Data center cabinet load capacity is limited, and copper-based heat sinks account for over 30% of the total weight, restricting high-density deployment.

The physical properties of diamond perfectly meet the above requirements:

• Thermal Conductivity: Single-crystal diamond (SCD) reaches 2000–2600 W/(m·K) at room temperature, 5–6 times that of copper.
• Coefficient of Thermal Expansion: 0.8–4.0×10⁻⁶ K⁻¹, highly compatible with semiconductors such as silicon, GaN and SiC.
• Density: 3.52 g/cm³, only 39% of copper, offering remarkable lightweight advantages.
• Insulation Performance: Resistivity ＞10¹² Ω·cm, enabling direct application as an insulating substrate.
• Nevertheless, the large-scale application of diamond in electronic heat dissipation has long been restricted by two core challenges: large-size single-crystal preparation and high-efficiency interfacial bonding. Two technological breakthroughs in April 2026 are providing industrial solutions to these bottlenecks.

II. Breakthrough I: Mass Production of 2-Inch Diamond Substrates Imminent, Breaking the Size Barrier

2.1 Technical Principle: Optimization of Step-Flow Growth Method

A Japanese enterprise (formerly Orbray) adopts an optimized step-flow growth method to deposit large-size single-crystal diamond on special sapphire substrates. The core innovation lies in the inclined substrate design:

Stress Release Mechanism: Traditional (100)-oriented diamond growth tends to generate high-density dislocations (＞10⁶ cm⁻²) due to lattice mismatch. The research team tilted the substrate by approximately 3–5° toward the (111) plane, enabling diamond crystals to grow layer by layer along step edges, effectively dispersing internal stress and reducing dislocation density to below 10⁴ cm⁻².

Temperature Gradient Control: The top of the deposition chamber is maintained at 1100–1150 °C, while the substrate zone is kept at 900–950 °C, forming a stable temperature gradient (ΔT≈200 °C). This gradient drives the dissociation of reaction gas (CH₄/H₂) in the high-temperature zone, allowing carbon atoms to arrange orderly on the low-temperature substrate surface.

Gas Ratio Optimization: CH₄ concentration is controlled at 1–2% with hydrogen flow of 200–300 sccm and pressure of 80–100 Torr. Low methane concentration inhibits amorphous carbon generation, while high hydrogen flow removes sp² hybridized carbon via atomic hydrogen etching to ensure crystal purity.

2.2 Performance Parameters: Surpassing Traditional Substrates

The prepared 2-centimeter square (approximately 2-inch diameter) diamond substrate exhibits outstanding performance: thermal conductivity as high as 2200–2600 W/(m·K), more than 10 times that of aluminum nitride (AlN); CTE of only 1.1×10⁻⁶/°C, highly matched with silicon chips (3×10⁻⁶/°C); surface roughness Ra＜0.5 nm, favorable for thin-film deposition; dielectric constant 5.7 (@1 MHz) reducing signal delay; breakdown field strength ＞10 MV/cm ensuring high-power reliability.

In GaN RF device tests, the diamond substrate lowered junction temperature from 185 °C to 112 °C and increased Power Added Efficiency (PAE) from 58% to 72%. In SiC power modules, operating temperature decreased by 40–60 °C while output power increased by over 30%.

2.3 Industrialization Roadmap: 2026 Productization Plan

The enterprise has formulated a clear mass production schedule:

• Q2 2026: Complete process verification of 2-inch diamond substrates with yield target over 80%.
• Q3 2026: Build the first demonstration production line with a planned capacity of 1,000 wafers per month.
• Q4 2026: Deliver samples to leading semiconductor clients and lock orders for 2027.

Initial applications focus on high-value-added scenarios:

• Microwave RF devices: 5G/6G base station power amplifiers, satellite communication T/R components.
• Laser diode packaging: High-power lasers, LiDAR light sources.
• Quantum computing: Heat dissipation layers for superconducting quantum bits, cold heads of dilution refrigerators.

2.4 Industrial Significance: Breaking International Monopoly

For a long time, aluminum nitride (AlN) substrates above 4 inches have been monopolized by Japan’s Kyocera and Germany’s CeramTec; 8-inch alumina (Al₂O₃) substrates are dominated by America’s CoorsTek. The mass production of 2-inch diamond substrates will realize an overtaking strategy:

• Performance Generation Gap: Thermal conductivity is an order of magnitude higher than AlN, skipping iterative upgrade cycles.
• Supply Chain Security: China supplies over 90% of global industrial diamond production (HPHT method), breaking dependence on overseas ceramic substrates.
• Value Upgrade: The unit price of diamond substrates is expected to reach 300–500 US dollars per piece, 3–5 times that of AlN substrates, greatly enhancing industrial chain added value.

III. Breakthrough II: Record-Breaking Interface Engineering, LED Junction Temperature Reduced by 72.8 °C

3.1 Technical Path: Multilayer Metallization Bonding Process

A Shenzhen research team (Shenzhen University of Technology) developed a diamond-metal gradient interface and optimized thermal transport through a four-layer structure:

Surface Activation: Ar ion bombardment (energy 500 eV, flow 20 sccm) cleans the diamond surface, removing contaminants and forming dangling bonds.

Transition Layer Deposition: Magnetron sputtering of TiC thin film (thickness 100±10 nm) achieves atomic-level bonding between diamond and metal via Ti-C chemical bonds.

Heat Conduction Layer Construction: Electroplated pure copper layer (thickness 3±0.5 µm); copper ductility relieves thermal stress while providing high lateral thermal conductivity.

Solder Layer Preparation: Evaporated Au₈₀Sn₂₀ eutectic solder (thickness 1±0.2 µm) with a melting point of 280 °C and excellent fluidity, ensuring the void rate of the chip-substrate interface is less than 3%.

Key process parameters:

• Annealing: Vacuum annealing at 500 °C (vacuum degree ＜5×10⁻⁴ Pa) for 30 minutes to promote Ti-Cu interdiffusion, with interfacial shear strength exceeding 200 MPa.
• Solder Reflow: Peak temperature 320 °C for 60 seconds under nitrogen protection to prevent oxidation.
• Pressure Control: Bonding pressure 5–10 MPa with uniform distribution to avoid local stress concentration.

3.2 Performance Breakthrough: Thermal Imaging Verifies Uniform Heat Dissipation

Under 3A constant current driving, temperature distribution comparison of LED chips packaged with three substrates shows:

Traditional Al₂O₃ substrate: maximum temperature 128.6 °C, surface temperature difference ≈45 °C, thermal resistance 8.2 K/W.

Optimized AlN substrate: maximum temperature 74.9 °C, temperature difference ≈22 °C, thermal resistance 4.7 K/W.

Diamond substrate (this technology): maximum temperature only 55.8 °C, surface temperature difference ≈8 °C, thermal resistance 2.1 K/W, achieving a record-high junction temperature reduction of 72.8 °C in the industry.

Physical mechanism: The TiC transition layer reduces contact thermal resistance by over 60%; the lateral thermal conductivity of diamond substrate exceeding 2000 W/(m·K) enables rapid heat diffusion; temperature uniformity suppresses the thermal lens effect and ensures color consistency.

3.3 Application Expansion: From LED to High-Power Electronics

This technology possesses broad migration potential:

• Laser Diode (LD): Diamond heat sinks control the junction temperature of 808 nm high-power LD below 60 °C, extending service life to over 100,000 hours (approximately 50,000 hours for traditional copper heat sinks).
• RF Power Devices: Suitable for GaN HEMT, LDMOS and other devices; under the 28 GHz frequency band, power density rises to 15–20 W/mm (vs traditional 8–10 W/mm).
• 3D Stacked Chips: Diamond heat sink layers can be embedded in silicon interposers to solve vertical thermal accumulation in 2.5D/3D packaging.

3.4 Industrial Significance: Establishing a Paradigm for High-Power Density Electronic Heat Dissipation

LED heat dissipation is only the starting point; the core value of this interface engineering technology lies in:

• Reproducibility: The multilayer metallization process is compatible with existing semiconductor production lines without major equipment renovation.
• Reliability: After 1000 hours of high-temperature storage at 200 °C, interfacial thermal resistance attenuation is less than 5%, meeting automotive-grade standards.
• Controllable Cost: Diamond accounts for about 70% of material cost. With the improvement of CVD deposition efficiency (rising from 5 µm/h to 20 µm/h), the unit area cost is expected to drop from 500 RMB/cm² to below 100 RMB/cm².

IV. Technological Synergy: Industrial Chain Resonance Between Substrates and Heat Sinks

4.1 Complementary Relationship: Material Preparation and Interface Engineering

The two breakthroughs respectively solve key upstream and downstream links of diamond heat dissipation: the Japanese enterprise’s diamond substrates focus on large-size single-crystal growth to provide high-quality wafers; the Shenzhen team’s diamond heat sinks focus on metal-diamond interface optimization to realize efficient heat transfer. Their synergy forms a three-level heat dissipation system of diamond-metal-chip, with theoretical thermal resistance reduced to below 1.5 K/W, supporting heat dissipation for 3000W-level chips.

4.2 Full Industrial Chain Layout: From Powder to Terminal Products

The diamond heat dissipation industrial chain has formed a complete layout:

• Upstream Raw Materials: A Henan enterprise’s annual 2 billion carat diamond powder project was approved in April 2026, providing core filler for thermal interface materials (TIM).
• Midstream Materials: Japanese diamond substrates, U.S. diamond-SiC liquid cooling plates (backed by NVIDIA’s 2 billion US dollar investment), and domestic CVD diamond thin films.
• Downstream Packaging: Shenzhen’s heat sink interface technology, Jiangsu enterprises’ diamond cutting tools for wafer dicing.
• Terminal Applications: AI accelerators, 5G base stations, new energy vehicle electronic control, offshore wind power braking systems (Jiangsu enterprise diamond friction gaskets).

4.3 Localization Progress: From "Industrial Teeth" to "Heat Dissipation Ace"

China has established global dominance in industrial diamond:

• Production Capacity Share: Over 90% of global HPHT single-crystal diamond output comes from China.
• Technological Upgrade: Transforming from micro-powder processing (abrasives, drill bits) to high-end functional materials (heat dissipation, optics, quantum).
• Capital Investment: Total investment in diamond heat dissipation related projects exceeded 5 billion RMB during 2025–2026, covering the entire chain of powder, thin films and composite materials.

A typical case of a Henan enterprise:

• Product matrix: Thermal conductive diamond thin film (1500–2000 W/(m·K)) → Thermal conductive diamond powder (filler) → Diamond-copper composite material (＞600 W/(m·K)).
• Client Breakthrough: Entered the supply chain of leading clients such as NVIDIA and Infinera, realizing value upgrading from "industrial teeth" to "heat dissipation ace".

V. Global Competition Pattern: Technological Route Divergence Among China, the US, Japan and Europe

5.1 United States: Focus on Military and AI Computing

Represented by Coherent, its diamond-SiC chemical bonding technology secured NVIDIA’s 2 billion US dollar investment, focusing on data center liquid cooling plates. Strengths lie in CVD equipment (about 60% global share), quantum sensing and national defense applications, with the strategic goal of ensuring independent controllability of AI computing heat dissipation.

5.2 Japan: Precision Manufacturing and Semiconductor Materials

Represented by Orbray and Sumitomo Electric, large-size single-crystal substrates target RF devices and power modules. Strengths lie in crystal growth technology, high-precision packaging and miniature heat sinks for consumer electronics, aiming to maintain leadership in high-end electronic materials.

5.3 Europe: Research-Driven and Special Applications

Represented by Element Six and Fraunhofer Institute, high-quality CVD diamond focuses on quantum technology and medical devices. Strengths include world-leading single-crystal quality (dislocation density ＜10³ cm⁻²), optical-grade applications and biocompatibility, seizing commanding heights in interdisciplinary fields.

5.4 China: Capacity Advantage and Industrial Chain Integration

China adopts a full-chain coverage route from HPHT powder to CVD thin films and composite materials. Advantages include cost control (1/3–1/5 of Europe and the US), independent industrial supporting and rapid market response. The strategic intention is to convert capacity advantages into high-end material competitiveness and realize transformation from "material export" to "solution output".

VI. Future Trends: Technological Evolution and Market Forecast 2026–2030

6.1 Technological Evolution Directions

• Size Breakthrough: Expanding from 2 inches to 4–6 inches to meet compatibility requirements of 300mm wafer fabs.
• Thermal Conductivity Upgrade: Isotopic purification (¹²C enrichment) pushes thermal conductivity beyond 3000 W/(m·K).
• Cost Reduction: CVD deposition rate rises from 5–10 µm/h to 50–100 µm/h, lowering unit area cost to below 50 RMB/cm².
• Heterogeneous Integration: Maturity of GaN-on-Diamond and Si-on-Diamond epitaxial technologies.

6.2 Application Scenario Expansion

• 2026–2027: Focus on data centers and 5G base stations; typical products include AI accelerator liquid cooling plates and RF power amplifier heat sinks, with market size estimated at 5–8 billion RMB.
• 2028–2029: Expand to new energy vehicles and photovoltaic inverters; IGBT heat dissipation substrates and SiC module substrates become key growth points, market size 12–18 billion RMB.
• 2030+: Enter cutting-edge fields such as quantum computing and terahertz communication; high-end applications including dilution refrigerator cold heads and terahertz windows emerge, with market size expected to reach 30–50 billion RMB.

6.3 Policy Impact

• Export Control: The US and Japan may list diamond heat dissipation materials as critical controlled materials, accelerating domestic substitution in China.
• Industrial Support: China’s "First Batch of New Materials" policy may cover diamond composite materials with premium subsidies.
• Standard Formulation: SEMI, JEDEC and other institutions will issue testing standards for diamond heat dissipation to regulate the market.

6.4 Risks and Challenges

• Technical Risks: Control of large-size diamond crystal defects and long-term interfacial reliability verification.
• Market Risks: Fluctuations in AI computing demand and performance improvement of alternative materials such as AlN and SiC.
• Supply Chain Risks: Supply stability of high-purity methane, hydrogen and other raw materials.

VII. Conclusion: Industrialization Inflection Point Arrives, Material Revolution Reshapes Heat Dissipation Pattern

The two breakthroughs in April 2026 — the 2-inch diamond substrate mass production plan of the Japanese enterprise and the record 72.8 °C LED junction temperature reduction achieved by the Shenzhen team’s interface engineering — are not isolated progresses, but dual symbols of the industrialization wave of diamond heat dissipation:

• Technological Maturity: Shifting from "whether it can be made" to "how large, how good, and how low-cost it can be", achieving comprehensive breakthroughs in size, performance and cost.
• Industrial Chain Synergy: Upstream powder (Henan), midstream substrates (Japan), and downstream packaging (Shenzhen) have formed a cross-border collaborative network.
• Market Driving: The 100-billion-level market demand from AI computing and new energy is driven by both capital and technology.

Implications for China’s industry:

• Short-term: Accelerate the localization of CVD equipment to replace US and German models and reduce material manufacturing costs.
• Medium-term: Build a "diamond-metal-ceramic" composite material system to meet the demands of diverse heat dissipation scenarios.
• Long-term: Layout application patents of diamond in quantum computing and terahertz communication to seize technological commanding heights.

Heat dissipation, once regarded as an auxiliary link, is rising to a key factor determining chip performance, reliability and energy consumption amid the material revolution. As the material with the highest thermal conductivity in nature, diamond will shine brilliantly in humanity’s journey toward exploring the limits of computing power.

Data Source: The technical analysis of this paper is based on industry updates as of April 4, 2026, including public information of the Japanese enterprise, the Shenzhen research team, and industrial data of Henan Enterprise A and U.S. enterprises. All enterprise names are referred to anonymously, focusing on technical essence and industrial trends.