Off-Center Wafer Edge Coating for Bow And Stress Control
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Solution Overview
Problem
Semiconductor fabrication processes induce non-uniform wafer stresses leading to bowing and distortions, which complicate subsequent processes and negatively impact yield due to overlay errors.
Innovation Solution
A method and apparatus for forming a shape control layer at the edge region of a wafer by modifying the internal stress of a shape control material using a chuck and film formation device, where the wafer is off-center placed, and the chuck rotates relative to the dispense nozzle to selectively apply the material, creating compressive or tensile stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fabrication processes are used, then semiconductor devices can be manufactured, but non-uniform wafer stresses cause bowing and distortions that reduce manufacturing precision
Solution Approach 1:
The patent applies preliminary anti-action by depositing a shape control material layer on the wafer surface that generates pre-compressive stress to counteract the tensile stresses and bowing that will develop during subsequent fabrication processes. This preventive measure is taken before the actual fabrication steps to maintain wafer flatness throughout manufacturing.
Solution Approach 2:
The patent changes the stress parameter of the wafer system by introducing a shape control material layer with specific compressive stress properties. The stress magnitude and distribution are controlled through material composition, layer thickness, and deposition parameters to achieve the desired wafer flatness correction.
2Manufacturing precision
If uniform shape control material is deposited across the entire wafer, then stress distribution is simplified, but edge region bowing cannot be effectively corrected
Solution Approach 1:
The patent applies local quality by concentrating the shape control material deposition specifically in the edge region of the wafer rather than uniformly across the entire surface. This localized deposition creates a non-uniform stress distribution that specifically addresses edge region bowing while leaving the center region unaffected.
Solution Approach 2:
The patent segments the wafer surface into different regions (edge region versus center region) and applies different treatments to each. The shape control material is selectively deposited only on the edge region, creating distinct functional zones with different stress characteristics to address region-specific bowing issues.
3Manufacturing precision
If wafer is placed off-center on the chuck, then edge region accessibility is improved, but positioning precision is reduced
Solution Approach 1:
The patent employs feedback mechanisms through metrology tools that measure wafer position and orientation on the chuck, and control systems that adjust the deposition process accordingly. Real-time monitoring ensures that even with off-center placement, the shape control material is deposited with the desired precision and uniformity in the edge region.
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 corrects wafer bowing and distortions, improving overlay accuracy and yield by optimizing stress distribution around the edge region.
Implementation Method 1
a shape control material that has its internal stress modified when reactive to a certain type of reaction
Implementation Method 2
The chuck can be configured to rotate with respect to the film formation device
Data Source
AI summary
Aspects of the present disclosure provide an apparatus for forming a shape control layer at an edge region of a wafer with respect to a rotational axis of the chuck. For example, the apparatus can include a chuck configured for a wafer to be off-center placed thereon. The apparatus can also include a film formation device configured to dispense on a surface of the wafer a shape control material that has its internal stress modified when reactive to a certain type of reaction. The chuck can be configured to rotate with respect to the film formation device.