Wafer Laser Processing with Sequential Modified Region Formation
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Solution Overview
Problem
The formation of modified regions in laser processing devices results in unstable crack amounts, leading to decreased processing quality due to cracks affecting each other's formation, especially when multiple condensing points are used, making it difficult to set appropriate processing conditions.
Innovation Solution
A laser processing device with an irradiation unit and imaging unit that forms modified regions sequentially and uses a control unit to adjust processing conditions based on real-time imaging feedback, ensuring accurate formation and quality of modified regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple condensing points are simultaneously formed in the thickness direction to improve formation speed, then productivity increases, but crack amount becomes unstable due to mutual interference between cracks from different modified regions
Solution Approach 1:
The patent applies preliminary action by forming outer modified regions first, then forming inner modified regions between them in a sequential manner rather than simultaneously. This staged approach allows cracks from outer regions to stabilize before inner regions are processed, preventing mutual interference while maintaining efficient multi-point processing.
Solution Approach 2:
The patent segments the modified region formation into distinct stages: first forming outer modified regions at multiple condensing points, then forming inner modified regions between them. This segmentation separates the crack formation processes in time, eliminating mutual interference while preserving the productivity benefits of multiple condensing points.
2Manufacturing precision
If modified regions are sufficiently separated to prevent crack connection, then crack amount stability improves, but processing complexity increases due to multiple processing steps
Solution Approach 1:
The patent employs dynamics by making the condensing point positions and processing conditions adjustable and adaptive. The system dynamically determines the spacing between outer and inner modified regions based on material properties and desired crack characteristics, optimizing the balance between crack stability and processing efficiency without fixed rigid constraints.
Solution Approach 2:
The patent utilizes parameter changes by varying laser processing conditions (energy density, pulse duration, scanning speed) and spatial parameters (distance between condensing points, depth of modified regions) to achieve stable crack formation. By adjusting these parameters, the system maintains crack stability without requiring excessively complex multi-step procedures.
3Manufacturing precision
If outer modified regions are formed first followed by inner modified regions, then crack connection and processing quality improve, but processing time increases due to sequential processing
Solution Approach 1:
The patent maintains continuity of useful action by performing outer and inner modified region formation in a continuous sequential process without intermediate interruptions. The laser processing continues uninterrupted, with the system simply adjusting condensing point positions and parameters between forming outer and inner regions, minimizing non-productive time while ensuring quality.
Solution Approach 2:
By forming outer modified regions preliminarily first, the system prepares the structural framework that guides subsequent inner region formation. This preliminary action enables faster inner region processing since the crack propagation paths are already established, reducing the overall time penalty of sequential processing.
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
Ensures the quality of the processed wafer by accurately determining and adjusting processing conditions, preventing cracks from reaching the surface, and maintaining desired crack lengths and connections, thereby improving the overall processing quality.
Implementation Method 1
an imaging unit that outputs light having a property of transmitting through the wafer, and that detects the light that has propagated through the wafer
Implementation Method 2
an irradiation unit that irradiates a wafer having a first surface and a second surface with a laser beam from a first surface side of the wafer
Data Source
AI summary
A laser processing device includes a control unit, and the control unit executes a first process of controlling a laser irradiation unit according to a first processing condition set such that a modified region and a modified region are formed inside a wafer; a second process of identifying a state related to each of the modified regions, and of determining whether or not the first processing condition is proper; a third process of controlling the laser irradiation unit according to a second processing condition set such that the modified regions are formed and a modified region is formed between the modified regions in a thickness direction of the wafer inside the wafer; and a fourth process of identifying a state related to each of the modified regions, and of determining whether or not the second processing condition is proper.