Laser Modified Layer Formation in Substrates with Stacked Articles
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Solution Overview
Problem
Existing methods for forming a modified layer inside a substrate using a laser beam are hindered when stacked articles absorb or reflect the laser, leading to incomplete formation of the modified layer, resulting in chipping, cracking, or deviation from predetermined dividing lines during substrate splitting.
Innovation Solution
A method where mapping data is used to identify and pre-form modified layers only at interrupted areas by the laser beam before stacking, followed by forming modified layers along the entire dividing lines after stacking, ensuring complete coverage and maintaining substrate strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a laser beam is directed along a predetermined dividing line with stacked articles on the optical path, then the substrate can be processed, but the laser beam is blocked by the stacked articles causing incomplete modified layer formation
Solution Approach 1:
The patent removes stacked articles from the optical path before laser beam irradiation to prevent blockage. By performing the removal action beforehand, the laser beam can successfully form the modified layer without interruption, ensuring complete and reliable modification along the entire predetermined dividing line
Solution Approach 2:
The stacked articles that cause harmful blockage are extracted or removed from the optical path before laser processing. This extraction eliminates the obstacle, allowing the laser beam to reach the substrate uniformly and form the modified layer completely without interruption
2Productivity
If external force is applied to split the substrate without complete modified layer formation, then substrate division can proceed, but chipping and cracking occur due to insufficient modified layer
Solution Approach 1:
The modified layer is formed completely along the entire predetermined dividing line before external force is applied for substrate splitting. This preliminary complete formation ensures that when division occurs, the modified layer is fully prepared to guide the split accurately without causing chipping or cracking, thereby maintaining both efficiency and precision
3Duration of action of moving object
If the laser beam is directed through stacked articles, then processing can continue, but the modified layer is not formed in areas blocked by stacked articles
Solution Approach 1:
Stacked articles are removed from the optical path before laser beam irradiation begins. This preliminary removal ensures that the laser beam can irradiate the substrate continuously and reliably along the entire predetermined dividing line without being blocked, resulting in complete and reliable modified layer formation
Solution Approach 2:
The stacked articles that cause blockage are extracted from the optical path before processing. This extraction eliminates interruptions in laser beam transmission, allowing continuous and reliable formation of the modified layer along the complete dividing line
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 approach prevents chipping and ensures precise splitting along predetermined lines, maintaining substrate strength and enabling smooth handling and stacking, even with stacked articles on the surface and metal films present.
Implementation Method 1
a laser beam capable of passing through a substrate is focused on the inside of the substrate and directed thereto along predetermined cutting lines to form a modified-layer inside the substrate
Implementation Method 2
a method of cutting a wafer by directing a laser beam to the wafer to form slits therein by a thermal transpiration phenomenon called ablation
Data Source
AI summary
First, mapping data storing interrupted areas is obtained. In a first modified-layer forming step, before a stacked article is stacked on a front surface of a substrate, a laser beam is directed to the interrupted areas based on the mapping data to form modified layers only at the interrupted areas. After the stacked articles have been stacked on the substrate, in a second modified-layer forming step, the laser beam is directed at least to the predetermined dividing line formed with no modified layer in the first modified-layer forming step to form a modified layer.