GaN-on-SOI Substrate Structure to Suppress Epitaxial Deformation
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Solution Overview
Problem
Nitride semiconductor substrates used in high-frequency devices experience plastic deformation during epitaxial growth due to stress, leading to degradation of second and third-harmonic characteristics, which is not adequately addressed by existing high resistivity silicon substrates.
Innovation Solution
A nitride semiconductor substrate is developed using a Silicon On Insulator (SOI) substrate with a single crystal silicon thin film containing nitrogen at a concentration of 2.0×10^14 atoms/cm^3 and a resistivity of 100 Ωcm or more, bonded to a low-resistivity single crystal silicon substrate via a silicon oxide layer of 10 to 400 nm thickness, to suppress plastic deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high resistivity silicon substrate is used to prevent signal flow and eliminate back-gate effect, then electrical insulation is improved, but plastic deformation occurs during epitaxial growth due to stress
Solution Approach 1:
The substrate is divided into two distinct parts: a high resistivity silicon substrate for electrical insulation and a low resistivity silicon substrate for mechanical support. This segmentation allows each layer to fulfill its specific function without compromising the other, resolving the contradiction between electrical insulation and structural stability
Solution Approach 2:
The invention creates a composite substrate structure combining high resistivity silicon and low resistivity silicon layers. This composite approach leverages the electrical properties of high resistivity material while utilizing the mechanical strength of low resistivity material, simultaneously achieving both electrical insulation and resistance to plastic deformation
2Reliability
If a silicon oxide layer is introduced between substrates to create SOI structure, then electrical separation is improved, but the complexity of substrate manufacturing increases
Solution Approach 1:
A silicon oxide layer is introduced as an intermediary between the high resistivity and low resistivity silicon substrates. This intermediate layer provides effective electrical separation and bonding interface, achieving reliable electrical isolation while maintaining a manageable manufacturing process through standard oxidation techniques
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 proposed substrate effectively suppresses plastic deformation and enhances high-frequency device characteristics by maintaining warp within acceptable limits, ensuring reliable and efficient epitaxial growth.
Implementation Method 1
SOI substrate in which a single crystal silicon thin film is formed on a single crystal silicon substrate via a silicon oxide layer
Implementation Method 2
the single crystal silicon thin film contains nitrogen at a concentration of 2.0×10^14 atoms/cm^3 or more and has a resistivity of 100 Ωcm or more
Data Source
AI summary
The present invention is a nitride semiconductor substrate for high frequency, which includes an SOI substrate in which a single crystal silicon thin film is formed on a single crystal silicon substrate via a silicon oxide layer, and a nitride semiconductor layer including a GaN layer formed on the SOI substrate; in which the single crystal silicon thin film contains nitrogen at a concentration of 2.0×1014 atoms/cm3 or more and has a resistivity of 100 Ωcm or more, the single crystal silicon substrate has a resistivity of 50 mΩcm or less, and the silicon oxide layer has a thickness of 10 to 400 nm. This can provide the nitride semiconductor substrate in which the nitride semiconductor layer is grown on the SOI substrate for manufacturing devices for high frequency, and the nitride semiconductor substrate with suppressed plastic deformation.