Substrate Processing Using Internal Laser Modified Regions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for dividing optical device wafers along division lines often result in die shift and incomplete separation, leading to complications in processing and potential damage during the separation of chips or dies, particularly with transparent crystal materials.
Innovation Solution
A method involving the application of a pulsed laser beam from the side of the substrate, where the focal point is located inside the substrate, creating modified regions entirely within the bulk without forming openings, allowing for precise removal of substrate material along division lines, thereby eliminating the need for external forces and ensuring accurate separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a pulsed laser beam is applied with focal point inside the substrate to create modified regions, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The laser creates modified regions in advance along the division lines before the actual separation process. These pre-formed modified regions serve as predetermined separation paths, enabling subsequent easy removal of substrate material along these lines without requiring complex real-time control during separation.
Solution Approach 2:
The substrate is divided into multiple discrete chips or dies by forming modified regions along division lines. This segmentation approach allows each chip to be separated independently while maintaining precise boundaries, resolving the contradiction between precision and complexity by breaking down the overall separation task into manageable segments.
2Productivity
If external force is applied using a breaking tool to divide the wafer, then productivity is improved, but manufacturing precision deteriorates due to die shift
Solution Approach 1:
The invention replaces the traditional mechanical breaking tool approach with a laser-based modification system. Instead of applying external mechanical force that causes die shift, the laser creates modified regions that guide subsequent material removal, eliminating the precision-loss mechanism inherent in mechanical breaking while maintaining high productivity.
Solution Approach 2:
The modified regions act as an intermediary between the laser processing and the final separation step. These regions serve as a bridge that translates the laser's precise energy deposition into controlled material removal paths, enabling accurate separation without direct mechanical contact that would cause die shift.
3Ease of manufacture
If the focal point is located at a distance from the front side to create hole regions, then ease of manufacture is improved, but manufacturing precision deteriorates due to incomplete separation
Solution Approach 1:
The laser parameters are optimized to create modified regions with specific local characteristics - fully contained within the substrate bulk without reaching the front or back surfaces. This local quality control ensures that the modified regions provide sufficient structural modification for complete separation while avoiding the creation of openings that would compromise manufacturing 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
This approach enables accurate, reliable, and efficient processing of substrates by preventing die shift and ensuring complete separation with controlled outer shapes, reducing the risk of damage and the need for subsequent inspection.
Implementation Method 1
applying a pulsed laser beam to the substrate from the side of the first surface in a condition where a focal point of the pulsed laser beam is located at a distance from the first surface in the direction from the first surface towards the second surface
Implementation Method 2
applying a pulsed laser beam to the substrate... so as to form a plurality of modified regions inside the substrate
Data Source
AI summary
A substrate has a first surface with at least one division line formed thereon and a second surface opposite the first surface. The substrate is processed by applying a pulsed laser beam from the side of the first surface. The substrate is transparent to the pulsed laser beam. The pulsed laser beam is applied at least in a plurality of positions along the at least one division line, a focal point of the pulsed laser beam located at a distance from the first surface in the direction from the first surface towards the second surface, so as to form a plurality of modified regions inside the substrate. Each modified region is entirely within the bulk of the substrate, without any openings open to the first surface or the second surface. Substrate material is removed along the at least one division line where the modified regions are present.