GaN Anodic Oxidation Etching with UV Light
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Solution Overview
Problem
Existing etching techniques for GaN materials, such as dry etching, cause significant damage and are complex, while wet etching methods like anodic oxidation etching aim to minimize damage but struggle with achieving high flatness, especially in forming recesses for semiconductor devices like MISFETs with trench gate structures.
Innovation Solution
The use of anodic oxidation etching on GaN materials with a specific etching voltage range of 0.16 V to 1.30 V, combined with UV light irradiation, to achieve a GaN material with an arithmetic mean line roughness of 15 nm or less on the bottom surface of recesses, thereby improving the flatness and reducing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ordinary dry etching is used to etch GaN materials, then the etching process is simple and fast, but significant damage is caused to the crystal structure and surface flatness deteriorates
Solution Approach 1:
The patent replaces mechanical/physical dry etching with electrochemical anodic oxidation etching. This substitution uses electrochemical reactions driven by UV light irradiation and applied voltage to remove material, avoiding the mechanical sputtering damage of dry etching while achieving comparable or better etching rates with superior surface quality and minimal crystal damage
Solution Approach 2:
The patent optimizes specific parameters of the anodic oxidation process: applying voltage in the range of 0.16V to 1.30V and using UV light with wavelength 365nm or less. These parameter changes enable controlled electrochemical etching that achieves high productivity while minimizing crystal damage and maintaining surface flatness
2Object-affected harmful factors
If anodic oxidation etching is used to minimize damage, then crystal damage is reduced, but achieving high surface flatness with Ra of 15 nm or less is difficult
Solution Approach 1:
The patent achieves high surface flatness by precisely controlling the anodic oxidation parameters: voltage between 0.16V and 1.30V, UV light wavelength of 365nm or less, and specific electrolyte conditions. These parameter optimizations enable the electrochemical etching to produce surfaces with Ra of 15 nm or less while maintaining minimal crystal damage
Solution Approach 2:
The patent employs periodic irradiation of UV light during the anodic oxidation process, alternating between irradiation and non-irradiation periods. This periodic action allows controlled material removal and surface smoothing, achieving high flatness while minimizing damage through pulsed electrochemical etching
3Object-affected harmful factors
If special dry etching techniques like neutral-beam etching or atomic layer etching are used to reduce damage, then crystal damage is minimized, but the device complexity increases significantly
Solution Approach 1:
The patent replaces complex specialized dry etching devices (neutral-beam etchers, atomic layer etchers) with a simpler electrochemical etching system using UV light irradiation and voltage application. This substitution achieves comparable or superior damage reduction without requiring complex vacuum systems, beam generation equipment, or precise thickness control mechanisms
Solution Approach 2:
The patent introduces UV light and electrolyte as intermediaries to mediate the etching process. The UV light activates the electrochemical reaction, and the electrolyte facilitates ion transport, enabling controlled material removal with minimal damage using simple, low-cost equipment compared to specialized dry etching devices
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 results in a GaN material suitable for semiconductor device processing with superior internal flatness and minimal crystal damage, as evidenced by the low profile roughness and high in-plane uniformity, enhancing the performance and reliability of semiconductor devices.
Implementation Method 1
anodic oxidation etching... while irradiating the GaN material with UV light
Implementation Method 2
anodic oxidation etching... by applying an etching voltage thereto
Data Source
AI summary
There is provided a new technology for anodic oxidation etching performed to GaN material having arithmetic mean line roughness Ra of 15 nm or less at a measurement length of 100 μm on a bottom surface of a recess when anodic oxidation etching is performed at an etching voltage of 1 V while irradiating the GaN material with UV light to form the recess of 2 μm in depth.