III-N Material Etching via Segmented Plasma Steps
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Solution Overview
Problem
Current methods for engraving III-N materials, such as AlGaN/GaN heterostructures, face issues with high defect creation and lack of precision in etching depth due to the use of chlorine-based plasmas, and slower etching speeds with bromine or fluorine plasmas, which affect the electrical properties and manufacturing efficiency of power electronic components.
Innovation Solution
A method involving a three-step process: initial engraving with a chlorine plasma, exposure to helium or hydrogen plasma to create defects, followed by chlorination and subsequent argon plasma etching, allowing for faster and more precise etching with reduced material damage and improved control over etching depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chlorine-based plasma is used for etching III-N materials, then etching speed is high, but defects are created in the engraved heterostructure
Solution Approach 1:
The etching process is divided into multiple sequential steps using different plasma chemistries: first a chlorine-based plasma for high-speed etching, then a bromine-based plasma for defect-free finishing. This segmentation allows each plasma type to perform its optimal function without suffering from the drawbacks of the other.
Solution Approach 2:
The patent introduces an intermediary step where a thin layer is formed by the first plasma that serves as a sacrificial layer. This intermediary layer enables the second plasma to complete the etching without directly attacking the underlying heterostructure, thus preventing defect formation while maintaining high overall etching speed.
2Reliability
If bromine or fluorine plasma is used for etching, then fewer defects are created, but etching speed is well below that of chlorine-based plasma
Solution Approach 1:
The etching process is divided into multiple sequential steps using different plasma chemistries: first a chlorine-based plasma for high-speed etching, then a bromine-based plasma for defect-free finishing. This segmentation allows each plasma type to perform its optimal function without suffering from the drawbacks of the other.
Solution Approach 2:
The patent changes the chemical composition parameter of the plasma between steps, transitioning from chlorine-based to bromine-based plasma. This parameter change allows the system to exploit the high etching speed of chlorine plasma for the bulk material and the high selectivity and low defect formation of bromine plasma for the final stages.
3Manufacturing precision
If ALE over-etching is implemented to achieve precise thickness control, then etching precision is improved, but the process time increases significantly
Solution Approach 1:
The etching process is divided into multiple sequential steps using different plasma chemistries: first a chlorine-based plasma for high-speed etching, then a bromine-based plasma for defect-free finishing. This segmentation allows each plasma type to perform its optimal function without suffering from the drawbacks of the other.
Solution Approach 2:
The patent maintains continuous useful action by having the second plasma immediately follow the first without interruption. The transition between plasmas is seamless, with the second plasma continuing the etching process where the first left off, thereby maintaining productivity while improving precision.
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 method achieves higher etching speeds compared to bromine or fluorine plasmas without increasing ionic energy, reduces material damage, and provides better control over etching depth, outperforming traditional chlorine-based and ALE over-etching processes.
Implementation Method 1
a plasma engraving is implemented in an ICP equipment using a chlorinated plasma
Implementation Method 2
The speed of such etching is high thanks to the desorption of GACL3 and ALCL3 species that are volatile
Implementation Method 3
exposure of at least a portion of a remaining thickness of the portion of the III-N material layer to a second plasma comprising helium or hydrogen
Implementation Method 4
Chlorination of the remaining thickness portion of the portion of the III-N material layer, transforming the portion of the remaining thickness into a layer of chlorinated material
Implementation Method 5
Second engraving of the chlorinated material layer, implemented using a third plasma with argon
Data Source
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AI summary
A method for etching at least a portion of a layer of III-N material, comprising carrying out the following steps: a) first etching (102) of a first part of the thickness of the portion of the layer of III-N material, carried out using a first plasma comprising chlorine; b) exposure (104) of at least a part of a remaining thickness of the portion of the layer of III-N material to a second plasma comprising helium or hydrogen; c) chlorination (106) of the remaining thickness of the portion of the layer of III-N material, transforming the remaining thickness of the portion of the layer of III-N material into a layer of chlorinated material; d) second etching (108) of the layer of chlorinated material, carried out using a third plasma comprising argon.