InAlN Layer Quality in Semiconductor Devices
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Solution Overview
Problem
The quality of InAlN layers in semiconductor devices deteriorates due to lattice distortion and cracking when Al composition in AlGaN electron supply layers increases, and high-temperature growth of GaN cap layers causes In sublimation, leading to poor epitaxial layer quality.
Innovation Solution
A method involving the formation of a first InAlN layer, a second InAlGaN layer grown at a higher temperature, and a third GaN, AlGaN, or InGaN layer, with controlled substrate temperature and source gas supply to maintain lattice matching and prevent In sublimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the Al composition of the AlGaN electron supply layer is increased to increase two-dimensional electron gas concentration, then the self-polarization difference and conduction band energy discontinuity increase, but lattice distortion increases and cracks occur
Solution Approach 1:
The invention changes the material composition parameter by replacing AlGaN with InAlN, which has different lattice constants and polarization properties. This parameter change allows achieving high two-dimensional electron gas concentration without the lattice distortion and cracking problems associated with high-Al-content AlGaN layers.
Solution Approach 2:
The invention uses a composite structure consisting of InAlN electron supply layer, GaN electron traveling layer, and InAlGaN buffer layer. This composite material approach combines the advantages of different nitride semiconductors to achieve both high electron concentration and lattice stability.
2Manufacturing precision
If the GaN cap layer is grown at high temperature to form the epitaxial layer, then the growth quality improves, but In sublimates from the InAlN electron supply layer causing quality deterioration
Solution Approach 1:
The invention introduces an InAlGaN buffer layer as an intermediary between the InAlN electron supply layer and the GaN cap layer. This buffer layer acts as a protective barrier that prevents In sublimation during high-temperature GaN growth while still allowing the formation of high-quality epitaxial layers.
Solution Approach 2:
The InAlGaN buffer layer is formed in advance before the high-temperature GaN cap layer growth. This preliminary action prepares a protective interface that prevents In sublimation during the subsequent high-temperature processing, ensuring the integrity of the InAlN layer.
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 suppresses lattice distortion and cracking, maintaining high two-dimensional electron gas concentration and improving the quality of the InAlN layer by ensuring continuous growth at optimized temperatures and gas flow rates.
Implementation Method 1
a two-dimensional electron gas is formed within the electron traveling layer due to spontaneous polarization and piezoelectric polarization between the electron traveling layer and the electron supply layer
Implementation Method 2
a two-dimensional electron gas is formed within the electron traveling layer due to spontaneous polarization and piezoelectric polarization between the electron traveling layer and the electron supply layer
Implementation Method 3
When the InAlN electron supply layer is grown at a high temperature, In is sublimated
Data Source
AI summary
A method of manufacturing a semiconductor device according to one aspect of the present invention includes a step of forming a first layer of InAlN, a step of forming a second layer of InAlGaN on the first layer under a growth temperature higher than that of the first layer, and a step of forming a third layer of GaN, AlGaN or InGaN under a growth temperature higher than that of the first layer.