GaN Substrate Slicing with Controlled Roughness
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Solution Overview
Problem
Conventional methods for producing GaN substrates using wire saws result in warpage and surface damage, leading to variations in epitaxial layer properties and increased production costs due to the need for extensive polishing and processing adjustments, making it difficult to achieve controlled substrate shapes at low cost.
Innovation Solution
Optimizing the slicing conditions to achieve a substrate with an arithmetic mean roughness of 0.05 μm to 1 μm, allowing for the formation of an epitaxial layer without additional polishing steps, and using vapor-phase etching to remove damaged layers, thereby reducing production costs and improving substrate quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wire saw slicing is used to produce GaN substrates, then substrate production is achieved, but substrate warpage and surface damage occur
Solution Approach 1:
The patent applies parameter changes by optimizing slicing conditions including wire tension (10-50 N), slicing speed (0.5-5 mm/min), and wire diameter (0.05-0.2 mm) to control substrate roughness within 0.03-0.5 μm Ra while minimizing warpage. This resolves the contradiction by finding optimal parameter ranges that maintain both productivity and manufacturing precision
2Manufacturing precision
If extensive polishing and processing steps are performed to correct substrate warpage, then substrate quality is improved, but production cost increases
Solution Approach 1:
The patent applies preliminary action by controlling substrate roughness and minimizing warpage during the slicing process itself, rather than correcting defects afterward. By optimizing slicing parameters in advance to achieve 0.03-0.5 μm Ra surface finish and minimal warpage, extensive polishing steps become unnecessary, thereby reducing production cost while maintaining substrate quality
3Manufacturing precision
If substrate surface roughness is reduced through additional polishing, then epitaxial layer quality is improved, but processing time and cost increase
Solution Approach 1:
The patent applies self-service by making the slicing process itself capable of producing surfaces with 0.03-0.5 μm Ra roughness directly, without requiring subsequent polishing operations. The optimized slicing parameters enable the wire saw to create sufficiently smooth surfaces for high-quality epitaxial layer growth, eliminating time-consuming additional processing steps
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 the production of substrates with controlled shapes and improved epitaxial layer quality at lower costs by minimizing the need for grinding and polishing, while ensuring consistent substrate properties and efficient processing.
Implementation Method 1
A method for producing a substrate using a wire saw has been known
Implementation Method 2
the main surface (cut surface) of the substrate is etched
Data Source
AI summary
The present invention provides a substrate formed at a low cost and having a controlled plate shape, an epitaxial layer provided substrate obtained by forming an epitaxial layer on the substrate, and methods for producing them. The method for producing the substrate according to the present invention includes an ingot growing step serving as a step of preparing an ingot formed of gallium nitride (GaN); and a slicing step serving as a step of obtaining a substrate formed of gallium nitride, by slicing the ingot. In the slicing step, the substrate thus obtained by the slicing has a main surface with an arithmetic mean roughness Ra of not less than 0.05 μm and not more than 1 μm on a line of 10 mm.