Nitride Semiconductor Substrate Edge Optical Detection
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Solution Overview
Problem
Conventional nitride semiconductor substrates are transparent to visible light and infrared light, making it impossible to achieve shape recognition and localization using existing methods developed for Si or GaAs substrates.
Innovation Solution
A nitride semiconductor substrate with chamfered edge portions is developed, where the ratio of average surface roughness of the chamfered edges to the main surface is controlled to be not more than 0.01, and the visible light transmissivity of the chamfered edges is not more than 0.2 times that of the main surface, allowing for optical recognition using visible or infrared light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the nitride semiconductor substrate is made transparent to visible light and infrared light, then the substrate quality is improved, but shape recognition and localization become impossible using existing optical methods
Solution Approach 1:
The patent applies surface treatment to the edge portions of the transparent nitride semiconductor substrate to modify its optical properties. By creating chamfered edges with specific surface roughness ratios (not more than 0.01), the edge portions reflect visible light differently from the transparent main surface, enabling optical detection of substrate boundaries without compromising substrate quality
Solution Approach 2:
The invention treats only the edge portions of the substrate differently from the main surface. The edge portions are given a specific surface roughness and chamfered geometry while the main surface remains transparent and high-quality. This localized modification enables edge detection while preserving the overall transparency and quality of the substrate
2Productivity
If the edge portion is smoothened to reduce cracks, then fabrication yield is improved, but optical recognition capability deteriorates
Solution Approach 1:
The surface treatment creates a controlled roughness pattern on the edge portions that changes how they interact with visible light. This treatment provides sufficient optical contrast for edge detection while maintaining smoothness that prevents crack formation during fabrication processes
Solution Approach 2:
The patent specifies precise parameter ranges for the edge portions, including surface roughness ratio (not more than 0.01) and chamfer dimensions. These parameter optimizations simultaneously achieve both crack prevention and optical detectability, resolving the contradiction between fabrication yield and edge detection capability
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
Enables clear optical recognition of the substrate contour and edge portions, facilitating easier handling and alignment in semiconductor device fabrication without requiring special light sources, while minimizing the risk of cracks and chipping during processing.
Implementation Method 1
The shape recognition and the localization of the substrate are frequently conduced by irradiating the substrate with visible light or infrared light and detecting light reflected by the substrate
Data Source
AI summary
A nitride semiconductor substrate includes a front surface, a rear surface on an opposite side to the front surface, and a first edge portion including a chamfered edge on the front surface. A ratio of an average surface roughness of the front surface to an average surface roughness of the first edge portion is not more than 0.01.