GaN Etching via Organometallic Chloride Precursors
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Solution Overview
Problem
Current methods for etching Gallium Nitride (GaN) surfaces are plagued by damage, nitrogen deficiency, and impurities, which hinder device performance, and existing growth techniques struggle with scalability and high dislocation densities, limiting the production of high-quality GaN-based devices.
Innovation Solution
The use of organometallic chlorine precursors, such as tertiarybutylchloride (TBCl), in an organometallic vapor phase epitaxy (OMVPE) reactor for in-situ and selective area etching and growth of GaN, allowing for low-temperature etching and high-speed growth with controlled ammonia levels to mitigate surface roughness and defect formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chlorine-based plasma etching is used to achieve anisotropic profile and vertical sidewall in GaN, then etching quality is improved, but plasma-induced damage and nitrogen deficiency are generated
Solution Approach 1:
The patent introduces an organometallic chlorine precursor as an intermediary substance that mediates the etching process. Instead of using direct chlorine plasma that causes damage, the organometallic precursor decomposes to provide chlorine atoms for etching while the organic portion acts as a protective intermediary, reducing plasma-induced damage and nitrogen deficiency in the GaN material
Solution Approach 2:
The patent changes the chemical parameters of the etching process by using organometallic chlorine precursors instead of conventional chlorine gas. This parameter change modifies the etching chemistry to be less damaging while maintaining the ability to produce anisotropic profiles and vertical sidewalls through controlled decomposition and reaction kinetics
2Adaptability or versatility
If conventional wet chemical etching is used to selectively attack c-plane GaN surfaces, then selective etching capability is improved, but surface roughness and bumps are created
Solution Approach 1:
The organometallic chlorine precursor serves as an intermediary that enables selective etching of c-plane GaN surfaces around dislocations while maintaining surface smoothness. The controlled decomposition and surface reaction mechanisms of the organometallic compound provide selectivity without the roughening effects of conventional wet chemicals
3Productivity
If hydrogen gas etching is used to etch GaN surfaces, then etching capability is achieved, but surface roughening by gallium droplets occurs
Solution Approach 1:
The organometallic chlorine precursor acts as an intermediary that provides etching capability without the gallium droplet formation problem of hydrogen gas etching. The chlorine from the precursor reacts with gallium to form volatile gallium chloride, preventing gallium droplet accumulation and associated surface roughening while maintaining high etching rates
4Manufacturing precision
If HVPE growth technique is used to achieve high growth rate and low dislocation density, then material quality is improved, but scalability from single wafer to mass production is limited
Solution Approach 1:
The organometallic chlorine precursor enables the OMVPE process to achieve both high growth rates and low dislocation densities, making the technique universally applicable for both single wafer and mass production scenarios. This multi-functionality allows OMVPE to compete with HVPE in material quality while surpassing it in scalability and throughput
5Adaptability or versatility
If OMVPE is used to produce versatile heterostructures with high throughput, then manufacturing versatility is improved, but growth rate is insufficient for thick drift layers
Solution Approach 1:
The patent changes the growth kinetics parameters by introducing organometallic chlorine precursors, which dramatically increase the growth rate from typical OMVPE rates of 5-10 μm/hour to rates exceeding 100 μm/hour. This parameter change enables the fabrication of thick drift layers (30-100 μm) while maintaining the versatility of OMVPE for producing complex heterostructures
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 enables defect-free, smooth, and scalable etching and growth of GaN surfaces, reducing plasma-induced damage and impurities, and achieving high etching rates and low dislocation densities, suitable for advanced GaN-based device fabrication.
Implementation Method 1
Vapor-phase etching in organometallic vapor-phase epitaxy (OMVPE) reactors (or in-situ etching), for example with hydrogen gas and hydrochloric acid, were reported.
Implementation Method 2
exposing a GaN layer or surface to an organometallic Cl precursor within a reactor under conditions sufficient to etch the layer or surface
Implementation Method 3
HIGH SPEED GROWTH OF GALLIUM NITRIDE BY ORGANOMETALLIC CHLORINE PRECURSORS
Implementation Method 4
organometallic vapor phase epitaxy (OMVPE) reactor for in-situ and selective area etching and growth of GaN
Data Source
AI summary
Methods and systems for in-situ and selective area etching of surfaces or layers, and high-speed growth of gallium nitride (GaN), by organometallic chlorine (Cl) precursors, are described herein. In one aspect, a method can include exposing a GaN layer or surface to an organometallic Cl precursor within a reactor under conditions sufficient to etch the layer or surface, thereby etching the GaN layer or surface. In another aspect, a method of growing GaN can include inputting a set of reactants comprising at least trimethylgallium (TMGa) and anunonia into an OMVPE reactor; inputting an organometallic Cl precursor into the OMVPE reactor; and reacting the Cl precursor with the TM Ga and with the NH3 to deposit GaN by organometallic vapor phase epitaxy.