Oriented Polycrystalline Diamond Wafer With Uniform Plasma Growth
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Solution Overview
Problem
The challenge of achieving ultra-high thermal conductivity and large-area homogeneity in diamond wafers for gallium nitride semiconductor components is hindered by issues such as plasma density distribution irregularities, impurity incorporation, and interface thermal resistance in traditional synthesis methods, limiting their effectiveness in heat dissipation.
Innovation Solution
A method involving a microwave plasma reactor with controlled plasma distribution and substrate preparation to form a uniform plasma field, combined with precise control of nucleation density, grain size, and impurity management, results in a polycrystalline diamond with consistent thermal performance across a large area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional substrate materials with low thermal conductivity are used, then manufacturing cost is reduced, but heat dissipation ability is limited
Solution Approach 1:
The invention changes the material parameter from traditional low-cost substrates to diamond material with exceptionally high thermal conductivity (2000-5000 W/(m·K)), resolving the contradiction by accepting higher material cost to achieve superior heat dissipation performance that enables higher power density operation
2Temperature
If composite materials like diamond/copper are used to improve thermal conductivity, then heat dissipation performance increases, but interface thermal resistance and bonding degradation occur
Solution Approach 1:
The invention extracts the diamond layer from composite material structures and uses it as a standalone substrate material, eliminating the interface thermal resistance and bonding degradation problems that plague diamond/copper composite materials while maintaining the ultra-high thermal conductivity benefit
3Productivity
If plasma density is increased to improve diamond growth rate, then productivity increases, but plasma distribution uniformity deteriorates
Solution Approach 1:
The invention dynamically adjusts plasma parameters during the growth process, optimizing plasma density and distribution uniformity at different growth stages to simultaneously achieve high growth rates and uniform plasma distribution across the substrate surface
4Temperature
If impurity content is reduced to improve thermal conductivity, then heat dissipation performance increases, but manufacturing complexity increases
Solution Approach 1:
The invention performs preliminary purification of the carbon source and growth environment before diamond deposition, and uses optimized plasma parameters to prevent impurity incorporation during growth, achieving ultra-low impurity content (nitrogen <100 ppb) while managing complexity through proactive rather than reactive purification
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method produces diamond wafers with a diameter of ≥100 mm and thermal conductivity of ≥1800 W/(m·K), ensuring consistent thermal performance across the wafer, addressing the limitations of existing technologies and enhancing heat dissipation for gallium nitride components.
Implementation Method 1
providing a microwave plasma reactor for the diamond growth to uniformly form a plasma containing carbon-hydrogen radicals above the substrate
Implementation Method 2
forming a structural modulation layer of the diamond or nucleation sites of the diamond on a substrate surface; providing a microwave plasma reactor for the diamond growth to uniformly form a plasma containing carbon-hydrogen radicals above the substrate
Implementation Method 3
performing a chemical vapor deposition on the substrate surface for an epitaxial growth of the diamond
Implementation Method 4
The thermal conduct in a diamond is mainly realized by vibrations (phonon heat conduction) of the crystal lattice or crystal point array. The carbon atoms of the diamond are bonded with sp3 bonds, which are covalent bond structures with strong polarity, and the Debye temperature thereof is high. The covalent bond between the carbon atoms has a high vibration frequency, and anharmonic effect in the crystal lattice dynamics is weak, so that the phonon scattering is smaller and the resistance of heat conduction mediated by the phonon is very small
Data Source
AI summary
An ultra-high thermal-conductivity diamond is provided. The ultra-high thermal-conductivity diamond is polycrystalline diamond with a highly oriented crystals along <110> or <100> direction. It has a diameter of ≥100 mm in linear dimension and a thickness of ≥300 m, a thermal conductivity of ≥1800 W/(m·K) at 298K, and at least one surface with Ra≤10 nm, and further includes one or more of the following features: a content of nitrogen impurity ≤100 ppb, a dielectric constant ≥5.4 a dielectric loss tangent tanδ≤6×10−5, a volume resistivity ≥1×1011 Ωm, and a breakdown voltage ≥1000 V. The method for synthesizing the ultra-high thermal-conductivity diamond includes: providing a substrate for the diamond growth and a microwave plasma reactor, and performing the epitaxial growth of the ultra-high thermal-conductivity diamond on the substrate surface by using the reactor.