Laser Parting of Crystalline Material With Imaging Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional wire sawing methods for cutting thin layers of crystalline materials, such as silicon carbide (SiC), result in significant material loss, high production costs, and non-uniform wafer thickness due to variations in material properties and optical properties within thick substrates, leading to challenges in fabricating uniformly thick wafers.
Innovation Solution
A method involving imaging and analysis of uncracked regions after forming subsurface laser damage in a substrate to determine when additional laser damage is necessary, adjusting laser parameters, and forming subsurface laser damage patterns to promote crack formation, followed by fracturing to yield uniformly thick substrate portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If wire sawing methods are used to cut thin layers of crystalline materials, then material can be separated into wafers, but significant material loss occurs and production costs increase
Solution Approach 1:
The patent replaces the mechanical wire sawing system with a laser-based system that uses optical energy to induce subsurface damage and thermal stress for wafer separation. The laser beam focuses energy at specific depths within the crystalline substrate, creating controlled damage zones without requiring mechanical contact, thereby eliminating material loss associated with mechanical cutting while maintaining high productivity
Solution Approach 2:
The patent utilizes changes in optical properties and absorption characteristics of the crystalline material at different depths and wavelengths to selectively create subsurface damage zones. By adjusting laser parameters (wavelength, pulse duration, intensity) and exploiting material property variations, the process achieves precise wafer separation with minimal material loss while maintaining high production efficiency
2Manufacturing precision
If conventional laser methods are used without imaging analysis, then processing is simpler, but uniform wafer thickness cannot be achieved due to variations in substrate properties
Solution Approach 1:
The patent implements a feedback control system where imaging devices capture real-time images of the substrate during laser processing. The system analyzes these images to detect variations in substrate properties and uncracked regions, then dynamically adjusts laser parameters to compensate for these variations, ensuring uniform wafer thickness while managing process complexity through automated control
Solution Approach 2:
The patent performs preliminary imaging and analysis of the substrate before and during laser processing to identify regions with varying optical properties. This preliminary assessment allows the system to pre-adjust laser parameters for different substrate zones, ensuring uniform wafer thickness is achieved throughout the entire substrate while maintaining manageable process complexity through systematic planning
3Reliability
If additional laser damage formation steps are performed to address uncracked regions, then wafer quality improves, but processing time increases
Solution Approach 1:
The patent applies partial action by performing additional laser damage formation only in specific regions where uncracked areas are detected through imaging analysis, rather than uniformly processing the entire substrate. This targeted approach improves wafer quality in problematic regions while minimizing additional processing time, achieving a balance between reliability and efficiency
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 reduces material loss and achieves uniformly thick wafers by optimizing laser damage formation, addressing variations in substrate properties and improving throughput and wafer quality.
Implementation Method 1
supplying emissions of a laser focused along a first average depth position within an interior of a crystalline material of a substrate... to form subsurface laser damage
Data Source
AI summary
A crystalline material processing method includes forming subsurface laser damage at a first average depth position to form cracks in the substrate interior propagating outward from at least one subsurface laser damage pattern, followed by imaging the substrate top surface, analyzing the image to identify a condition indicative of presence of uncracked regions within the substrate, and taking one or more actions responsive to the analyzing. One potential action includes changing an instruction set for producing subsequent laser damage formation (at second or subsequent average depth positions), without necessarily forming additional damage at the first depth position. Another potential action includes forming additional subsurface laser damage at the first depth position. The substrate surface is illuminated with a diffuse light source arranged perpendicular to a primary substrate flat and positioned to a first side of the substrate, and imaged with an imaging device positioned to an opposing second side of the substrate.