Grooved Silicon Substrate Structure for Stress-Relieved GaN Epitaxy
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Solution Overview
Problem
Current epitaxial growth techniques on silicon substrates face challenges such as poor uniformity and cracking due to thermal expansion and lattice mismatch between silicon and gallium nitride layers.
Innovation Solution
A silicon substrate structure is designed with grooves formed along specific lattice directions, allowing for compressive space during temperature changes, thereby reducing stress and enhancing epitaxial growth stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epitaxial growth is performed on silicon substrate with gallium nitride layers, then semiconductor components can be manufactured, but thermal expansion and lattice mismatch cause stress accumulation and substrate warping
Solution Approach 1:
The invention introduces groove structures that divide the continuous silicon substrate into segmented regions. These grooves create discrete stress relief zones that allow the substrate to accommodate thermal expansion and lattice mismatch stresses without accumulating continuous stress across the entire substrate, thereby preventing warping and improving epitaxial growth stability
Solution Approach 2:
The invention applies local stress relief by creating grooves at specific locations and orientations on the silicon substrate. The grooves are strategically positioned to address local stress accumulation points caused by thermal expansion and lattice mismatch, providing targeted stress management rather than uniform treatment across the entire substrate
2Reliability
If gallium nitride layer thickness is increased to improve device performance, then better semiconductor functionality is achieved, but tensile strain and compressive stress increase causing cracks
Solution Approach 1:
The invention incorporates groove structures as preventive stress relief features before cracks can form. These grooves act as cushioning elements that accommodate stress accumulation from thick gallium nitride layers, preventing the stress from reaching critical levels that would cause cracking, thereby enabling thicker layers for better device performance
3Manufacturing precision
If temperature is increased during epitaxial growth to improve material quality, then better epitaxial film formation is achieved, but thermal expansion increases causing more warping
Solution Approach 1:
The invention introduces groove structures at specific locations and orientations on the silicon substrate to provide localized stress relief. These grooves are strategically positioned to address thermal expansion stresses that occur during high-temperature epitaxial growth, allowing better material quality formation while maintaining substrate shape uniformity through targeted stress management
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 substrate structure effectively reduces cracking and enhances epitaxial uniformity and production yield by providing a mechanism for strain release during temperature variations.
Implementation Method 1
the expansion due to high temperature causes the gallium nitride layers to become thicker, while silicon substrate expands with increasing temperature
Implementation Method 2
when the temperature decreases, the compressed silicon lattice from the high-temperature state gradually consolidates
Data Source
AI summary
A silicon substrate structure has a substrate, a first groove, a second groove and a third groove. The substrate includes a first surface and a second surface. The first surface is formed on one side of the Si(111) lattice plane, and the second surface is formed on the opposite side of the Si(111) lattice plane. The first groove is disposed along a first direction on the second surface. The second groove is disposed along a second direction on the second surface. The third groove is disposed along a third direction on the second surface. The first direction is defined as the direction from the Si(111) lattice plane to the Si(1-1-1) lattice plane, the second direction is defined as the direction from the Si(-11-1) lattice plane to the Si(1-11) lattice plane, and the third direction is defined as the axial direction of the Si[1-10] lattice orientation.