Laser Wafer Separation Layer Shaping to Reduce Warpage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wafer manufacturing methods using laser processing result in significant warpage due to the expansion of modified regions, making it difficult to transport and process wafers.
Innovation Solution
A method involving the application of a laser beam with a wavelength that transmits through the ingot, positioning the focal point deeper than the front surface to form a three-dimensional separation layer, and grinding the separation surface to remove the modified regions, thereby reducing warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a laser beam is applied to form a separation layer with modified regions, then wafer separation is achieved, but warpage occurs due to expansion of the modified region
Solution Approach 1:
The patent applies local quality by creating a three-dimensional separation layer where the modified region has varying depth across different locations. The focal point of the laser beam is positioned at different depths in different regions of the ingot, creating modified regions with non-uniform distribution. This local variation in modification depth compensates for the expansion effects and reduces overall warpage while maintaining effective separation.
2Manufacturing precision
If the separation surface is ground to remove the modified region, then separation quality improves, but warpage makes wafer transport difficult
Solution Approach 1:
The patent applies preliminary anti-action by pre-compensating for warpage through the three-dimensional separation layer design before the wafer is fully processed. The non-uniform depth distribution of modified regions is intentionally designed to counteract the expansion forces that would otherwise cause warpage, thereby maintaining wafer flatness throughout subsequent handling and transport operations.
3Manufacturing precision
If the focal point is positioned deeper than the front surface to form modified regions, then separation is achieved, but significant warpage results
Solution Approach 1:
The patent applies dimensionality change by transitioning from a two-dimensional uniform separation approach to a three-dimensional non-uniform separation layer. The focal point depth is varied in the vertical dimension across different horizontal locations, creating a three-dimensional distribution of modified regions. This additional dimensional control enables effective separation while compensating for expansion-induced warpage.
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
The method effectively reduces wafer warpage and improves grinding efficiency by forming a three-dimensional separation surface, allowing for easier handling and uniform thickness.
Implementation Method 1
applying a laser beam having a wavelength that transmits through the ingot from a front surface of the ingot and positioning a focal point of the laser beam at a position deeper than the front surface of the ingot to form a modified region
Implementation Method 2
relatively feeding the ingot and the focal point for processing to form a separation layer including a plurality of the modified regions inside the ingot
Implementation Method 3
grinding a separation surface of the wafer to remove the modified region
Data Source
AI summary
A method for manufacturing a wafer from an ingot includes: holding the ingot; applying a laser beam having a wavelength that transmits through the ingot from a front surface of the ingot and positioning a focal point of the laser beam at a position deeper than the front surface of the ingot to form a modified region, and relatively feeding the ingot and the focal point for processing to form a separation layer including a plurality of the modified regions inside the ingot; separating, from the ingot, a workpiece including the front surface of the ingot as the wafer, with the separation layer as a start point; and grinding a separation surface of the wafer to remove the modified region. In the applying, a depth of the focal point forming the modified region is changed to form the separation surface into a three-dimensional shape rather than a horizontal surface.