GaN Substrate Surface Cleaning via Surfactant Polishing
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Solution Overview
Problem
Conventional polishing methods for GaN substrates fail to sufficiently reduce the probability of defects in epitaxially grown layers, leading to unevenness and quality deterioration due to residual acid materials and silicon atoms on the substrate surface.
Innovation Solution
The method involves reducing the concentration of chlorine and silicon atoms on the GaN substrate surface by using a polishing solution with a surface-active agent and controlling the ambient gas atmosphere to minimize acid material adsorption, with specific limits set for chlorine atoms (≤2×10^14/cm²) and silicon atoms (≤3×10^13/cm²) to prevent surface roughness and haze, ensuring a high-quality epitaxial layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional polishing methods are used to reduce haze level, then surface haze is reduced, but defects such as unevenness occur in the epitaxially grown layer
Solution Approach 1:
The patent changes the chemical composition parameters of the polishing solution by adding specific concentrations of hydrochloric acid (0.01-1 wt%) and surfactants (0.01-1 wt%), which modifies the polishing mechanism to reduce haze while preventing surface defects that would affect epitaxial layer uniformity
Solution Approach 2:
The patent introduces surfactants as intermediary substances in the polishing solution that mediate between the abrasive particles and the GaN substrate surface, enabling effective haze reduction while maintaining surface integrity for high-quality epitaxial growth
2Object-affected harmful factors
If polishing is performed to improve surface quality, then haze is reduced, but acid materials and silicon atoms remain on the surface causing defects
Solution Approach 1:
The patent converts the potentially harmful strong acid environment into a benefit by using hydrochloric acid in the polishing solution to effectively remove haze while the surfactant simultaneously prevents excessive acid and silicon residue, transforming what could be a contamination source into a controlled surface preparation process
Solution Approach 2:
The patent carefully controls the concentration parameters of hydrochloric acid (0.01-1 wt%) and surfactant (0.01-1 wt%) in the polishing solution to achieve optimal balance between haze removal effectiveness and minimization of residual contaminants on the substrate surface
3Manufacturing precision
If chlorine-based gases are used for dry etching to remove process-transformed layer, then the layer is removed, but surface contamination due to metal particles occurs
Solution Approach 1:
The patent uses surfactant-containing polishing solution as an intermediary cleaning step between dry etching and epitaxial growth, where the surfactant mediates the removal of metal particle contaminants that would otherwise remain on the surface after chlorine-based dry etching
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 substrate with a reduced haze level and improved surface roughness, enabling the formation of high-quality epitaxial layers with enhanced light emission intensity, thereby reducing the probability of semiconductor device failures.
Implementation Method 1
controlling the ambient gas atmosphere to minimize acid material adsorption
Implementation Method 2
an epitaxially grown layer is formed by epitaxy
Data Source
Figure 1~3
Figure 4
AI summary
A group III nitride substrate on which an epitaxially grown layer of good quality can be formed, and a method of manufacturing the same are obtained. A GaN substrate (1) is one of the following: a group III nitride substrate, wherein the number of atoms of an acid material per square centimeter of a surface (3) is not more than 2×1014, and the number of silicon atoms per square centimeter of the surface (3) is not more than 3×1013; a group III nitride substrate, wherein the number of silicon atoms per square centimeter of a surface (3) is not more than 3×1013, and a haze level of the surface (3) is not more than 5 ppm; and a group III nitride substrate, wherein the number of atoms of an acid material per square centimeter of a surface (3) is not more than 2×1014, and a haze level of the surface (3) is not more than 5 ppm.