Composition Adjusting Layer for Epitaxial Stress Balancing
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Solution Overview
Problem
Semiconductor compound structures grown epitaxially on substrates often face issues such as cracking, warping, and high dislocation density due to thermal and lattice mismatches between the substrate and the epitaxially grown material.
Innovation Solution
A semiconductor structure is developed with composition adjusting layers made of semiconductor compounds, where the atomic percentage of a first element is gradually decreased and then increased along the epitaxial direction, with the thickness of the gradual decrease section being greater than the gradual increase section, creating a stress field that balances tensile stress and reduces dislocation density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a semiconductor compound structure is epitaxially grown on a substrate, then the semiconductor component can be formed, but thermal mismatch and lattice mismatch cause tensile strain leading to cracking, warping, and high dislocation density
Solution Approach 1:
The patent introduces composition adjusting layers as intermediary structures between the substrate and the semiconductor compound structure. These layers have gradually changing composition (e.g., Al content in AlGaAs) that acts as a mediator to transition the lattice constant and thermal expansion coefficient from the substrate to the epitaxial layer, reducing the harmful tensile strain while maintaining structural stability.
Solution Approach 2:
The patent changes the compositional parameters of the adjusting layers gradually through the epitaxial growth direction. By controlling the atomic percentage of different elements (e.g., decreasing Al content then increasing it) in the adjusting layers, the lattice constant and thermal properties are continuously adjusted to minimize mismatch-induced strain.
2Manufacturing precision
If the atomic percentage of the first element is gradually decreased and then increased in the composition adjusting layer, then compressive stress is induced to balance tensile stress and reduce dislocation density, but the layer structure becomes more complex
Solution Approach 1:
The composition adjusting layer is segmented into multiple sub-layers with different compositional profiles. Each sub-layer has a specific function: the first section decreases the first element content to induce compressive stress, while the second section increases it to adjust the overall composition. This segmentation allows precise control of stress and dislocation density despite the increased structural complexity.
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 approach effectively reduces dislocation density and prevents cracking and warping by inducing compressive stress, ensuring the epitaxial structure remains stable during cooling.
Implementation Method 1
the substrate and the semiconductor compounds epitaxially grown on the substrate may have different thermal expansion coefficients and lattice constants, thus a great thermal mismatch and lattice mismatch between the substrate and the epitaxially grown structure may be caused
Implementation Method 2
the substrate and the semiconductor compounds epitaxially grown on the substrate may have different thermal expansion coefficients and lattice constants, thus a great thermal mismatch and lattice mismatch between the substrate and the epitaxially grown structure may be caused
Implementation Method 3
A component action layer made of semiconductor compounds is generally prepared by epitaxial growth on a substrate
Data Source
AI summary
The present invention discloses a semiconductor structure and a method for manufacturing the semiconductor structure. The semiconductor structure includes: a substrate; and at least one composition adjusting layer disposed above the substrate; wherein each of the at least one composition adjusting layer is made of a semiconductor compound, the semiconductor compound at least comprises a first element and a second element, and an atomic number of the first element is less than an atomic number of the second element, wherein in each of the at least one composition adjusting layer, along an epitaxial direction of the substrate, an atomic percentage of the first element in a compound composition is gradually decreased at first and then gradually increased, a thickness of a gradual decrease section is greater than a thickness of a gradual increase section.