Multi-Buffer Epitaxial Structure for Stress-Balanced Semiconductor Layers
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Solution Overview
Problem
The imbalance of compressive and tensile stress, along with defects such as dislocation, in the epitaxial layer of semiconductor components, leads to cracking and reduced reliability and service life.
Innovation Solution
A semiconductor component design incorporating multiple buffer layers with varying materials and thicknesses to balance stress and reduce lattice mismatch, using materials like AlGaN, InAlN, and AlN to create compressive and tensile stresses that cancel each other out, thereby reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single buffer layer is used between substrate and epitaxial layer, then the structure is simple, but the stress cannot be balanced and lattice mismatch cannot be sufficiently reduced
Solution Approach 1:
The buffer layer is divided into multiple sub-layers (first buffer sub-layer, second buffer sub-layer, third buffer sub-layer) with different materials and thicknesses. Each sub-layer addresses specific stress and lattice mismatch issues, transforming a single complex buffer layer into multiple simpler, functional segments that collectively solve the stress balance problem while maintaining overall structural simplicity
Solution Approach 2:
Different regions of the buffer layer have different material compositions and thicknesses optimized for local requirements. The first buffer sub-layer (30-100 nm AlGaN) addresses interface stress, the second buffer sub-layer (100-300 nm InAlN) addresses lattice mismatch, and the third buffer sub-layer (30-100 nm AlN) provides surface preparation, with each region having tailored properties for its specific function
2Length of moving object
If the epitaxial layer thickness is increased to meet performance requirements, then the performance improves, but the cracking risk increases due to unbalanced stress
Solution Approach 1:
The multi-layer buffer structure is designed to preemptively counteract the stress that will develop in the thick epitaxial layer. By establishing a gradient of lattice constants and stress states in the buffer layers before depositing the thick epitaxial layer, the system prevents stress accumulation that would otherwise lead to cracking, enabling thicker epitaxial layers to be grown without failure
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
This design effectively balances stress and reduces defects, enhancing the reliability and service life of semiconductor components by improving subthreshold characteristics and on-off ratios.
Implementation Method 1
lattice constants of the first buffer sub-layer and the second buffer sub-layer are different. In this way, there is compressive stress between the first buffer sub-layer and the second buffer sub-layer. In addition, there is tensile stress between the substrate and the first buffer layer
Implementation Method 2
compressive stress and tensile stress of the epitaxial layer need to be balanced, to avoid cracking of the epitaxial layer
Data Source
AI summary
A semiconductor component may include a substrate, a first buffer layer, a second buffer layer, and a channel layer that are disposed in a stacked manner. The first buffer layer includes at least two first buffer sub-layers that are disposed in the stacked manner, and a second buffer sub-layer is disposed in the stacked manner between the at least two first buffer sub-layers. A first material is used for each of the at least two first buffer sub-layers, and a second material is used for the second buffer sub-layer. Elements included in the first material are not totally the same as elements included in the second material.