SiC Laser Processing with In-Situ Resistance-Based Parameter Control
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Solution Overview
Problem
Existing laser processing methods for silicon carbide (SiC) wafers face inefficiencies due to variations in impurity concentration, leading to non-uniform laser processing and potential defects, and require additional steps like fluorescence or resistance measurements, which increase man-hours and decrease throughput.
Innovation Solution
A laser processing apparatus and method that measures electric resistance or fluorescence in real-time during processing, adjusting laser conditions based on measured impurity concentrations or photon counts to improve throughput by parallel execution of measurements and processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser processing conditions are adjusted according to electric resistivity measured in advance, then manufacturing precision is improved, but productivity deteriorates due to additional measurement steps
Solution Approach 1:
The patent combines the resistance measurement function and laser processing function into a single integrated apparatus. The resistance measurement unit and laser processing unit share the same physical platform and control system, allowing measurement and processing to occur in sequence without moving the workpiece between separate devices, thereby eliminating transportation time and setup overhead.
Solution Approach 2:
The patent implements continuous processing by immediately performing laser processing on the workpiece after resistance measurement without interruption. The control unit automatically transitions from measurement mode to processing mode, maintaining continuous engagement with the workpiece and eliminating idle time between measurement and processing steps.
2Manufacturing precision
If fluorescence detecting step is performed to measure impurity concentration distribution, then manufacturing precision is improved, but productivity deteriorates due to increased measurement time
Solution Approach 1:
The patent extracts the essential measurement parameter (electric resistance) that directly correlates with impurity concentration, eliminating the need for time-consuming fluorescence detection. By measuring electric resistance at different positions, the system obtains sufficient information about impurity distribution without performing complex optical measurements.
Solution Approach 2:
The patent replaces the fluorescence detection system (optical measurement) with an electrical resistance measurement system. This substitution uses electrical properties instead of optical properties to characterize the workpiece, achieving the same goal of mapping impurity distribution with faster and simpler measurements.
3Productivity
If same laser processing conditions are applied to all regions, then productivity is improved, but manufacturing precision deteriorates due to impurity concentration variations
Solution Approach 1:
The patent applies different laser processing conditions to different regions of the workpiece based on locally measured resistance values. The control unit divides the workpiece into multiple regions, each with its own resistance characteristics, and adjusts laser parameters (power, speed, pulse duration) according to the specific impurity concentration of each region, ensuring optimal processing quality throughout.
Solution Approach 2:
The patent implements dynamic adjustment of laser processing conditions during the processing operation. Instead of using fixed parameters, the system continuously adapts laser settings based on real-time resistance measurements and the pre-established resistance-processing condition correspondence, allowing processing parameters to change dynamically as the laser moves across different regions of the workpiece.
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
Enhances throughput by allowing simultaneous measurement and processing, reducing man-hours and minimizing defects by adapting laser conditions to regional impurity variations in SiC ingots.
Implementation Method 1
forming the above-described separating layer by multiphoton absorption that occurs at a condensing point of the laser beam passing through the SiC ingot
Implementation Method 2
the higher the impurity concentration of nitrogen, the higher the absorptivity of a laser beam
Implementation Method 3
measure electric resistance or electric resistivity of the workpiece via the first measurement head
Implementation Method 4
maintain or change a condition for processing the workpiece by the laser beam to be applied to the measurement target region according to the electric resistance or the electric resistivity
Data Source
AI summary
A laser processing apparatus includes a holding unit, a laser beam irradiating unit, a processing feed unit, a first resistance measuring apparatus including a first measurement head, and a controller, the controller being configured to, when irradiating a workpiece with a laser beam while moving the holding unit and a condenser relative to each other along a processing feed direction, measure electric resistance or electric resistivity of a measurement target region of the workpiece by using the first measurement head and maintain or change a condition for processing the workpiece by the laser beam to be applied to the measurement target region according to the electric resistance or the electric resistivity of the measurement target region.