Wafer Etching Patterns for Bow and Warp Reduction
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Solution Overview
Problem
Conventional wafers, especially those that are large-sized, insufficiently rigid, ultra-thin, or with internal crystal stress, are prone to deformation due to gravity or external forces, affecting their geometric shape and quality during subsequent dicing processes.
Innovation Solution
A wafer processing method involving the formation of etching patterns on the wafer surface, either recessed inward or protruding outward, to reduce the impact of internal stress and external forces, using a fixture pattern to target stress concentration areas and adjust the wafer's geometry through etching and grinding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wafer is made large-sized to increase production capacity, then productivity is improved, but the wafer becomes insufficiently rigid and deforms under gravity or external forces
Solution Approach 1:
The patent applies local quality by creating etching patterns at specific locations on the wafer surface, particularly at the periphery and stress concentration areas. These localized etched regions modify the stress distribution locally without affecting the entire wafer structure, allowing large wafers to maintain rigidity while preserving production capacity benefits
2Weight of moving object
If the wafer is made ultra-thin to reduce gravity impact, then weight is reduced, but the wafer becomes more susceptible to deformation from external forces
Solution Approach 1:
The patent changes the physical parameters of the wafer surface by creating etching patterns with specific depths and geometries. These parameter changes modify the mechanical properties of the wafer, enhancing its resistance to deformation while maintaining the ultra-thin design that reduces weight and gravity impact
3Ease of manufacture
If the wafer has internal crystal stress to enable material growth, then manufacturing capability is improved, but the internal stress causes geometric shape deformation
Solution Approach 1:
The patent converts the harmful effect of internal crystal stress into a beneficial outcome by strategically placing etching patterns at stress concentration areas. The etching process releases and redistributes the internal stress, transforming the deformation-causing stress into a controlled feature that actually improves wafer flatness and geometric shape
4Manufacturing precision
If etching patterns are formed to reduce warpage, then manufacturing precision is improved, but the process complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the wafer surface into different regions with distinct etching patterns. Instead of applying a uniform etching process across the entire wafer, specific patterns are created at peripheral regions and stress concentration areas, simplifying the overall process while achieving precise control over wafer flatness
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 geometric warpage such as bow and warp in wafers by adjusting the internal stress and external forces, improving the wafer's shape and quality post-processing.
Implementation Method 1
A first etching step is performed on the second portion of the first surface to form a first etching pattern on the first surface of the wafer
Implementation Method 2
after the second surface of the wafer is ground, a convex pattern is formed on the second surface
Data Source
AI summary
A wafer and a wafer processing method are included. The wafer processing method includes the following steps. A wafer is provided having a first surface and a second surface opposite to the first surface. A fixture pattern is pasted on the first surface to cover a first portion of the first surface of the wafer, and a second portion of the first surface is exposed by the fixture pattern. A first etching step is performed on the second portion of the first surface to form a first etching pattern on the first surface of the wafer. The fixture pattern is removed from the first surface, and the second surface of the wafer is ground.