Ga2O3 In-Situ Etching With Gallium Precursors for Vertical Fins
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing etching methods for gallium oxide (Ga2O3) cause subsurface damage, charge depletion, and non-stoichiometric surfaces, making it difficult to form scaled sub-micron fins/trench structures and reducing Schottky barrier heights.
Innovation Solution
An in-situ etching method using metal organic gallium precursors like trimethyl gallium and triethyl gallium in a MOCVD reactor, where the precursors undergo pyrolysis to deposit gallium on the Ga2O3 surface, forming volatile gallium suboxide that etches the epilayer, allowing for controlled etch rates and smooth surface morphology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dry etching is used on Ga2O3, then etching can be performed, but subsurface damage occurs resulting in charge depletion and degradation of mobility
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using metal organic gallium precursors instead of traditional dry etching chemicals. This parameter change transforms the etching mechanism to produce volatile gallium suboxide, enabling damage-free etching while maintaining high etch rates and vertical sidewall formation.
Solution Approach 2:
The patent introduces gallium metal organic precursors as intermediary substances that mediate the etching process. These precursors decompose to form gallium adatoms that react with Ga2O3 to create volatile gallium suboxide, serving as an intermediate reaction product that enables clean removal of material without subsurface damage.
2Productivity
If wet etching is used on Ga2O3, then etching can be performed, but angled sidewalls are formed making formation of scaled sub-micron fins/trench structures difficult
Solution Approach 1:
The patent changes the physical-chemical parameters of the etching environment by using vapor-phase metal organic precursors at controlled temperatures and pressures. This enables precise control over the etching front propagation, producing vertical sidewalls essential for sub-micron fin and trench structures rather than the angled sidewalls produced by wet etching.
3Productivity
If metal assisted chemical etching is used on Ga2O3, then etching can be performed, but non-stoichiometric etched surfaces are formed leading to reduced Schottky barrier heights
Solution Approach 1:
The patent uses gallium adatoms as intermediaries that react with Ga2O3 surface atoms in a controlled manner. The gallium adatoms form volatile gallium suboxide with the surface oxygen, enabling stoichiometric removal of Ga and O atoms in the correct ratio. This intermediary mechanism prevents the non-stoichiometric surface composition that would otherwise reduce Schottky barrier heights.
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 enables damage-free fabrication of 3D structures like fins and trenches with vertical sidewalls, improving the quality of Ga2O3 epilayers and allowing integration with regrowth of epilayers and dielectrics without breaking vacuum, resulting in reduced surface roughness and increased etch rates.
Implementation Method 1
the precursor is introduced into the reactor and undergoes pyrolysis, depositing Ga on the β-Ga2O3 surface
Implementation Method 2
The Ga adatoms react with Ga2O3 to form volatile gallium suboxide (Ga2O), which desorbs from the β-Ga2O3 surface and etches the epilayer
Data Source
AI summary
Damage-free etching of Ga2O3 includes loading a Ga2O3 sample in a metal organic chemical vapor deposition (MOCVD) reactor, heating the Ga2O3 sample, and contacting the Ga2O3 sample with a metal organic gallium precursor to yield gallium and hydrocarbon components, thereby etching the Ga2O3 sample with the gallium. The Ga2O3 includes β-phase (monoclinic) Ga2O3, α-phase (corundum) Ga2O3, κ-phase (orthorhombic) Ga2O3, γ-phase (defective spinel) Ga2O3. The metal organic gallium precursor includes triethyl gallium (TEGa), and trimethyl gallium (TMGa).