Silane Gas Etching for GaN Wafer Crystallinity
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Solution Overview
Problem
Existing methods for manufacturing gallium nitride (GaN) wafers face challenges in controlling etch shape and density, leading to poor crystallinity and complex, time-consuming processes, particularly with ex-situ methods like ELO and HCl-based etching which struggle with dislocation propagation and uniformity.
Innovation Solution
A method involving the formation of an etch stop layer, followed by etching with silane gas to create specific profiles such as voids or pyramidal shapes in the GaN layer, allowing for in-situ etching and improved control over etch shape and density, thereby enhancing crystallinity and luminance in light emitting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If HCl gas is used for etching to improve crystallinity, then etch pits are formed, but control over etch shape and etch density becomes difficult
Solution Approach 1:
The patent changes the chemical parameter by substituting HCl gas with silane gas for etching. This parameter change enables precise control over etch shape and etch density while maintaining the ability to form etch pits for improving crystallinity, thereby resolving the contradiction between crystallinity improvement and manufacturing precision
2Stability of the object's composition
If ex-situ methods like ELO or PE are used to grow high-quality nitride semiconductor, then crystalline quality improves, but process complexity and manufacturing time increase
Solution Approach 1:
The patent combines the etching process with in-situ regrowth in a single continuous process. By performing etching with silane gas followed by immediate regrowth of nitride layer without removing the wafer from the reactor, the method merges multiple steps into one, reducing process complexity while maintaining high crystalline quality
Solution Approach 2:
The in-situ regrowth process allows the system to automatically repair and improve the crystal structure immediately after etching. The regrowth process self-corrects defects and propagates high-quality crystal structures without requiring external intervention or additional complex processing steps
3Shape
If ELO method is used with mask patterning, then lateral overgrowth is achieved, but manufacturing time and process steps increase
Solution Approach 1:
The patent extracts and eliminates the mask patterning step from the traditional ELO process. By using silane gas etching followed by in-situ regrowth, the method achieves lateral overgrowth without requiring external masks, photolithography steps, or wafer removal, thereby dramatically reducing manufacturing time while maintaining the lateral overgrowth effect
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 easy control over etch shape and density, improves crystallinity, and facilitates the formation of high-density voids for luminance enhancement and self-splitting, reducing manufacturing time and complexity while producing high-quality thick film GaN wafers.
Implementation Method 1
etching a portion of the first GaN layer with a silane gas
Data Source
AI summary
A method for manufacturing a gallium nitride (GaN) wafer is provided. In the method for manufacturing the GaN wafer according to an embodiment, an etch stop layer is formed on a substrate, and a first GaN layer is formed on the etch stop layer. A portion of the first GaN layer is etched with a silane gas, and a second GaN layer is formed on the etched first GaN layer. A third GaN layer is formed on the second GaN layer.