Laser Processing Wafer Substrates with Depth-Stratified Modified Regions
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Solution Overview
Problem
During laser processing of element-group formation substrates, electronic elements are often deteriorated when forming intersecting cutting portions, leading to poor chip formation and reduced yields.
Innovation Solution
A laser processing method where modified regions are formed at different depths from the back surface of the substrate, with specific directions and depths to minimize interference and ensure precise cutting, using a configuration that includes forming first, second, and third modified regions along distinct directions with varying depths to prevent deterioration of electronic elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple modified regions are formed by laser irradiation in intersecting directions inside the substrate, then complete cutting portions are achieved, but electronic elements are deteriorated at intersecting regions
Solution Approach 1:
The patent applies dimensionality change by forming modified regions at different depth positions within the substrate thickness direction. Instead of forming all modified regions at the same depth plane, the invention creates a three-dimensional arrangement where first modified regions and second modified regions are positioned at different depths, thereby avoiding intersection at the same depth level and preventing element deterioration while maintaining cutting precision.
Solution Approach 2:
The patent segments the cutting process into multiple stages by forming different types of modified regions (first modified regions and second modified regions) at different depth positions. This segmentation allows the cutting function to be distributed across multiple depth layers, with each layer contributing to the overall cutting without causing harmful intersections at the same depth.
2Device complexity
If laser light is focused at the same depth for all cutting portions, then processing is simplified, but element deterioration occurs at intersecting regions
Solution Approach 1:
The patent resolves this contradiction by introducing the depth dimension as a differentiating factor. Instead of varying laser parameters at the same depth plane (which would increase complexity), the invention varies the depth position itself, creating a simpler control strategy where different cutting portions are processed at different depth levels to avoid harmful intersections.
3Object-affected harmful factors
If modified regions are formed at different depths, then element deterioration is suppressed, but processing time increases
Solution Approach 1:
The patent applies preliminary action by forming modified regions at different depth positions in a planned sequence. The first modified regions are formed at a first depth, and the second modified regions are formed at a second depth, creating a predetermined three-dimensional structure that prevents element deterioration while optimizing processing efficiency through advance planning of the depth-based processing sequence.
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 method effectively suppresses the deterioration of electronic elements, ensuring accurate and efficient division of substrates into individual chips with improved yield and reduced occurrence of discoloration or formation failures.
Implementation Method 1
forming a modified region in a first direction being along a surface of a plate-shaped substrate and other modified region in a second direction being along the surface of the substrate and different from the first direction are formed inside the substrate by irradiating an element-group formation substrate, in which plural electronic elements are formed on a front surface of the substrate, with laser light from a back surface side of the substrate
Implementation Method 2
focusing laser light inside the semiconductor substrate and performing irradiation
Data Source
AI summary
In a modified region forming step, an element-group formation substrate (20) having plural semiconductor light emitting elements (21) formed on a substrate front surface (11a) of a wafer substrate (11) is irradiated with laser light (64) from the substrate back surface (11b) of the substrate, thereby forming the following inside the substrate: first and third modified regions (L1) and (L3) oriented in a y-direction (corresponding to a first direction) that is parallel to the surfaces of the substrate; and second and fourth modified regions (L2) and (L4) oriented in an x-direction (corresponding to a second direction) that is parallel to the surfaces of the substrate and differs from the y-direction. In the step, the first modified region (L1), the second modified region (L2), the third modified region (L3) and the fourth modified region (L4) are formed at different depths from the substrate back surface of the substrate.