Single-Crystal Substrate Division via Shield Tunnel Laser Ablation
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Solution Overview
Problem
Existing methods for dividing single-crystal substrates, such as sapphire and gallium nitride substrates, require multiple laser applications along the same division line, leading to poor productivity and challenges in processing substrates with films on the front or back side, as they are affected by the films during laser processing.
Innovation Solution
A processing method involving a film removing step using a cutting blade or etching, followed by shield tunnel formation with a pulsed laser beam that permeates through the substrate, creating fine holes and amorphous regions along division lines, allowing for reliable division of the substrate without affecting films on the surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a laser beam is applied multiple times to the same division line to divide the substrate, then the division completeness is improved, but the productivity deteriorates
Solution Approach 1:
The patent applies a preliminary action by performing a film removing step before laser processing. The cutting blade or etching process removes films along the division lines in advance, creating a clean surface that allows the laser beam to effectively form shield tunnels with a single application. This preliminary preparation eliminates the need for multiple laser applications, thereby resolving the contradiction between division completeness and processing speed.
2Stability of the object's composition
If films are present on the substrate surface during laser processing, then the substrate structure is preserved, but the laser processing reliability deteriorates
Solution Approach 1:
The patent applies segmentation by separating the film removal operation from the laser processing operation. The film removing step using a cutting blade or etching process selectively removes films only along the division lines, while the laser processing step subsequently forms shield tunnels in the exposed substrate regions. This segmentation allows films to be preserved in device regions while enabling reliable laser processing in division line regions.
Solution Approach 2:
The patent applies local quality by creating different surface conditions in different regions of the substrate. The film removing step creates a distinct local condition along division lines where films are absent, while device regions retain their film coverage. This local differentiation enables the laser beam to reliably form shield tunnels only where needed, without being affected by films in device regions.
3Reliability
If a cutting blade or etching process is used to remove films, then the laser processing effectiveness is improved, but the device complexity increases
Solution Approach 1:
The patent applies preliminary action by performing film removal using a cutting blade or etching process before laser processing. This preliminary step prepares the division line regions by removing films, enabling the subsequent laser processing to effectively form shield tunnels with a single application. Although this adds a process step, it eliminates the need for multiple laser applications, thereby improving overall laser processing effectiveness.
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 enables reliable laser processing of single-crystal substrates with films, increasing productivity by allowing division with a single pulsed laser application, even on substrates with complex surface structures, and improves device quality by minimizing debris and surface roughness.
Implementation Method 1
applying a pulsed laser beam having a wavelength which permeates through the single-crystal substrate along the division lines to form shield tunnels, each shield tunnel including a fine hole and an amorphous region shielding the fine hole
Data Source
AI summary
Disclosed herein is a processing method of a single-crystal substrate having a film formed on a front side or a back side thereof to divide the single-crystal substrate along a plurality of preset division lines. The method includes a film removing step of removing the film along the division lines, a shield tunnel forming step of applying a pulsed laser beam having a wavelength which permeates through the single-crystal substrate along the division lines to form shield tunnels, each including a fine hole and an amorphous region shielding the fine hole, in the single-crystal substrate along the division lines, and dividing step of exerting an external force on the single-crystal substrate to which the shield tunnel forming step is performed to divide the single-crystal substrate along the division lines.