SiC Ingot Facet Detection via Fluorescence Intensity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
It is challenging to detect the facet region of a silicon carbide (SiC) single crystal ingot, which is crucial for uniform laser processing, as the facet and non-facet regions differ in refractive index and optical characteristics, making it difficult to form modified layers at a uniform depth, leading to increased kerf loss during wafer slicing.
Innovation Solution
A detecting method and apparatus that irradiate the SiC single crystal ingot with light to generate fluorescence, allowing for the determination of facet regions based on fluorescence intensity, enabling separate processing conditions for each region to form modified layers uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a laser beam is applied to form modified layers in SiC single crystal ingot, then wafer slicing can be performed, but the facet and non-facet regions differ in refractive index causing modified layers to form at different depths
Solution Approach 1:
The patent applies different laser processing conditions (different laser power, scanning speed, or focal depth) specifically for facet regions versus non-facet regions. The laser processing apparatus includes a region identification unit that detects whether the current position is a facet or non-facet region, and a control unit that adjusts processing parameters accordingly to ensure uniform modified layer depth across both region types.
Solution Approach 2:
The patent changes laser processing parameters (power, scanning speed, focal position) based on the detected region type. By dynamically adjusting these parameters when transitioning between facet and non-facet regions, the system compensates for refractive index differences and achieves consistent modified layer formation depth throughout the SiC single crystal ingot.
2Measurement precision
If visual inspection is used to distinguish facet and non-facet regions, then region identification is possible for thin wafers, but it becomes difficult for thicker SiC single crystal ingots
Solution Approach 1:
The patent replaces visual inspection (mechanical/optical observation) with a fluorescence-based detection system. A fluorescence microscope or imaging device excites the SiC ingot surface and detects fluorescence intensity variations, which differ between facet and non-facet regions due to their distinct crystallographic orientations and optical properties. This method provides accurate region identification regardless of ingot thickness.
Solution Approach 2:
The patent introduces fluorescence as an intermediary signal to indirectly identify region types. Instead of directly observing physical or visual differences that become imperceptible in thick ingots, the system uses fluorescence emission as a mediator that amplifies and makes detectable the underlying structural differences between facet and non-facet regions.
3Ease of manufacture
If uniform laser processing conditions are applied across the entire SiC single crystal ingot, then processing is simple, but modified layers form at non-uniform depths due to regional refractive index differences
Solution Approach 1:
The patent transitions from static, uniform laser processing conditions to dynamic, adaptive processing conditions. The system continuously monitors the ingot surface using fluorescence detection, identifies region boundaries in real-time, and dynamically adjusts laser parameters on-the-fly as the laser beam scans across different regions, maintaining both operational simplicity and processing precision.
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 efficient detection of facet regions, reducing SiC loss during wafer slicing by allowing for tailored laser processing conditions, thereby minimizing kerf loss and improving the uniformity of modified layer formation.
Implementation Method 1
irradiating the first surface of the SiC single crystal ingot with light from a light source; detecting fluorescence generated from the first surface of the SiC single crystal ingot by the light
Data Source
AI summary
A facet region detecting method for detecting a facet region of an SiC single crystal ingot includes: an irradiation step of irradiating a first surface of the SiC single crystal ingot with light; a fluorescence intensity detection step of detecting the intensity of fluorescence generated from the first surface of the SiC single crystal ingot by the light; and a determination step of determining a region of the first surface where the fluorescence intensity is comparatively low as a facet region and determining a region where the fluorescence intensity is comparatively high as a non-facet region.