Stress Modulated Group III-V Semiconductor Buffer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional group III-V semiconductor devices grown on silicon substrates face limitations due to lattice mismatch and thermal expansion differences, leading to substrate deformation, warping, and cracking, which restricts the thickness of the buffer layer and subsequently the breakdown voltage of the semiconductor device.
Innovation Solution
A compositionally graded body is introduced over the substrate, featuring a first region with compressive stress and a stress modulating region with tensile stress, allowing for the growth of thick, high-quality buffer layers without significant warping or cracking, enabling increased breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick buffer layer is used to achieve high breakdown voltage, then the breakdown voltage is improved, but substrate deformation and cracking occur due to lattice mismatch and thermal expansion differences
Solution Approach 1:
The patent applies parameter changes by systematically varying the aluminum composition in graded buffer layers. The aluminum content increases progressively from the substrate interface toward the active region, changing the physical parameters of each layer to match lattice constants and thermal expansion coefficients, thereby reducing stress and enabling thick buffer layers without substrate deformation
Solution Approach 2:
The patent uses composite materials by creating a multi-layered buffer structure with varying compositions. Each buffer layer has a specific aluminum content that differs from adjacent layers, forming a composite structure that collectively manages stress while providing the necessary electrical isolation and support for high breakdown voltage operation
2Strength
If various compensating layers are added to prevent substrate deformation, then substrate integrity is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by making each buffer layer position-specific in composition. The aluminum content is tailored to the local stress conditions at each depth from the substrate, with lower aluminum content near the substrate and higher content toward the active region. This localized compositional control provides stress management throughout the structure without requiring additional complex components
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 solution enables the formation of thick, continuous buffer layers with enhanced breakdown voltage, suitable for high power applications, while minimizing substrate deformation and maintaining device integrity.
Implementation Method 1
a first region applying compressive stress to said substrate, wherein said first region includes a first stress layer and a second stress layer formed on said first stress layer
Implementation Method 2
a stress modulating region applying tensile stress to said substrate, wherein said stress modulating region includes a third stress layer formed on said second stress layer
Implementation Method 3
due to lattice mismatch and differences in thermal expansion characteristics between III-nitride materials and silicon, thick III-nitride layers can produce substantial deformation of the silicon wafer
Implementation Method 4
differences in thermal expansion characteristics between III-nitride materials and silicon
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
According to one embodiment, a group III-V semiconductor device comprises a compositionally graded body disposed over a substrate and below a buffer layer supporting an active area of the group III-V semiconductor device. The compositionally graded body includes a first region applying compressive stress to the substrate. The compositionally graded body further includes a stress modulating region over the first region, where the stress modulating region applies tensile stress to the substrate. In one embodiment, a method for fabricating a group III-V semiconductor device comprises providing a substrate for the group III-V semiconductor device and forming a first region of a compositionally graded body over the substrate to apply compressive stress to the substrate. The method further comprises forming a stress modulating region of the compositionally graded body over the first region, where the stress modulating region applies tensile stress to the substrate.