Nitride Semiconductor Interlayers Reduce Dislocation and Stress
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Solution Overview
Problem
Nitride-based semiconductor devices on silicon substrates face challenges with increased dislocation density and tensile stress due to lattice constant and thermal expansion coefficient mismatches, making it difficult to reduce both dislocation density and cracks simultaneously.
Innovation Solution
The implementation of a semiconductor device structure with alternating interlayers of Alx0Iny0Ga1-x0-y0N and step-graded or superlattice layers between clad layers, along with buffer layers like AlN, to reduce dislocation density and tensile stress by managing stress distribution and energy band alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a nitride thin film grows on a Si substrate, then heat conductivity is improved and warpage is reduced, but dislocation density increases and cracks are generated due to lattice and thermal expansion mismatches
Solution Approach 1:
The patent divides the interface between nitride thin film and Si substrate into multiple discrete buffer layers with different compositions and thicknesses. Each buffer layer segment addresses specific aspects of the mismatch problem, creating a stepped transition zone that progressively adapts the lattice structure rather than a single abrupt interface.
Solution Approach 2:
The patent introduces buffer layers as intermediary structures between the nitride thin film and Si substrate. These buffer layers serve as mediator materials with graded compositions that bridge the gap between the two mismatched materials, reducing both dislocation density and thermal stress through progressive composition changes.
2Reliability
If islands are grown by using a SiNx dislocation reduction layer, then dislocation density is reduced, but tensile stress increases and cracks are generated
Solution Approach 1:
The patent systematically changes multiple parameters of the buffer layers including composition ratios, thicknesses, and material types across different layers. By controlling these parameters in a graded manner, the patent reduces dislocation density while simultaneously managing stress accumulation to prevent crack formation.
Solution Approach 2:
The patent employs composite buffer layer structures combining different materials (e.g., AlN, AlGaN, InGaN) with specific composition ratios. These composite structures provide both dislocation filtering and stress management functions that single-material layers cannot achieve alone.
Data Source
AI summary
A semiconductor device may reduce a dislocation density and tensile stress by forming a plurality of interlayers between neighboring clad layers. The semiconductor device may include a plurality of clad layers on a substrate and a plurality of interlayers between neighboring clad layers.