Diamond Substrate Manufacturing via Pillar Coalescence
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Solution Overview
Problem
Current methods for manufacturing diamond substrates using heteroepitaxial growth are limited to substrates with a maximum diameter of 1.5 inches due to stress and warp issues, preventing the production of larger substrates required for semiconductor applications.
Innovation Solution
A diamond substrate manufacturing method involving the growth of pillar-shaped diamonds on a base substrate, followed by coalescence and separation to form a large diamond substrate layer with a diameter of two inches or more, utilizing the stress generated by lattice and thermal expansion differences to prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If heteroepitaxial growth method is used to form diamond substrate on base substrate, then coupling boundaries are eliminated and substrate area is not restricted, but stress is generated due to lattice constant and thermal expansion coefficient differences causing warp or crack
Solution Approach 1:
The invention divides the diamond substrate into a plurality of diamond single crystal regions that are grown separately on the base substrate. Each region grows independently as a pillar-shaped diamond single crystal, avoiding the formation of coupling boundaries while maintaining large substrate area. The regions are arranged in an array pattern with intervals between them, allowing stress to be distributed and managed.
Solution Approach 2:
The invention performs preliminary formation of pillar-shaped diamond single crystals before they coalesce to form the final substrate. By controlling the growth process to form discrete pillars first, then allowing them to merge, the stress generated during growth is managed in a controlled manner rather than in a continuous monolithic structure, preventing warp and crack.
2Area of stationary object
If mosaic growth method is used to arrange plural diamond single crystal substrates, then large substrate size is achieved, but coupling boundaries are formed where crystal quality deteriorates
Solution Approach 1:
Instead of arranging separate diamond single crystal substrates that would create coupling boundaries, the invention segments the growth process itself by forming multiple pillar-shaped regions that grow independently and then coalesce. This creates a single continuous crystal structure without the quality-deteriorating boundaries that occur when pre-formed substrates are joined.
Solution Approach 2:
The invention merges multiple pillar-shaped diamond single crystal regions into a single continuous substrate through controlled coalescence during the growth process. This combining occurs at the atomic level during epitaxial growth, creating a uniform crystal structure without the macroscopic coupling boundaries that would form if separate substrates were physically joined.
3Area of stationary object
If diamond single crystals grow randomly in coupling boundary area, then coalescence occurs from various directions, but large amount of potential is generated causing distinct boundary lines
Solution Approach 1:
The invention establishes predetermined positions and orientations for each diamond single crystal region before growth begins. The pillar-shaped regions are formed with controlled spacing and alignment, preventing random growth directions that would lead to uncontrolled potential energy accumulation and distinct boundary lines. The growth process follows a predetermined pattern from the outset.
Solution Approach 2:
The invention applies different growth conditions and constraints to different local regions of the substrate. Each pillar-shaped diamond single crystal region grows with controlled orientation and spacing, allowing local optimization of crystal quality and stress distribution. This localized control prevents the random coalescence that generates harmful potential energy and visible boundary lines.
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
Enables the production of large diamond substrates with diameters up to two inches or more, reducing stress and preventing cracks by releasing it through the destruction of pillar-shaped diamonds, thus simplifying the manufacturing process and improving substrate quality.
Implementation Method 1
causing diamond single crystals to newly grow on the diamond single crystal substrates using a homoepitaxial growth method
Implementation Method 2
forming a diamond film on the base substrate by a heteroepitaxial growth method
Implementation Method 3
a stress is generated in crystals of a diamond substrate formed by growth due to a difference in lattice constant and thermal expansion coefficient between the base substrate and the diamond
Data Source
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AI summary
A diamond substrate is formed of diamond single crystals by preparing a base substrate; forming plural pillar-shaped diamonds formed of diamond single crystals on one side of the base substrate; causing a diamond single crystal to grow from a tip of each pillar-shaped diamond and coalescing the diamond single crystals growing from the tips of the pillar-shaped diamonds to form a diamond substrate layer; separating the diamond substrate layer from the base substrate; and manufacturing a diamond substrate from the diamond substrate layer, a shape in an in-plane direction of the diamond substrate is a circular shape or a circular shape having an orientation flat plane formed therein and has a diameter of two inches or more.