Tapered Superstrate Edge for Spin-Coating Bead Control
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Solution Overview
Problem
Inkjet Adaptive Planarization (IAP) processes face challenges with superstrates due to edge beads formed during spin coating, which reduce usable surface area and require additional defect-prone treatment operations to remove, affecting surface planarity and throughput.
Innovation Solution
A superstrate design with a central region and a tapered edge region, where the taper angle is not greater than 20 degrees, allowing the edge bead to be formed within the tapered edge region with its apex below the central region's coating plane, thereby avoiding the need for subsequent edge bead removal and enhancing surface planarity and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spin coating is used to apply coating on superstrate, then coating can be applied efficiently, but edge bead is formed at outer end reducing usable surface area
Solution Approach 1:
The superstrate is segmented into a central region and a tapered edge region. The tapered edge region acts as a sacrificial zone that captures the edge bead, separating it from the central region which maintains full coating coverage and usability.
Solution Approach 2:
The harmful edge bead is extracted and relocated to the tapered edge region through the geometric design. The taper angle causes the edge bead to form and accumulate at the outer end of the tapered region rather than on the central working surface.
2Manufacturing precision
If subsequent treatment operations are used to remove edge bead, then surface planarity can be improved, but additional work effort and defects are introduced
Solution Approach 1:
The tapered edge region is pre-formed on the superstrate before coating application. This preliminary geometric modification prevents edge bead formation on the central region, eliminating the need for subsequent removal operations.
Solution Approach 2:
The edge bead, which is normally a defect requiring removal, is converted into a beneficial feature by redirecting it to the tapered edge region. The taper geometry ensures the edge bead forms within the sacrificial zone, turning a harmful byproduct into a harmless or even useful element.
3Manufacturing precision
If tapered edge region is designed with small taper angle, then edge bead apex stays below coating plane, but manufacturing complexity increases
Solution Approach 1:
The taper angle is optimized to be between 0-20 degrees, which is sufficient to redirect the edge bead below the coating plane while remaining manufacturable. This parameter range balances the competing requirements of surface planarity and ease of fabrication.
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 design ensures high surface planarity, extended superstrate lifetime, and increased usable surface area without the need for additional processing steps, reducing the risk of defects and improving manufacturing efficiency.
Implementation Method 1
The coating is typically applied by spin coating
Implementation Method 2
the tapered edge region can have a taper angle of not greater than 20 degrees relative to a radial direction of the superstrate blank
Data Source
AI summary
A superstrate can comprise a superstrate blank and a coating overlying an outer surface of the superstrate blank. The superstrate blank can comprises a central region and a tapered edge region, wherein the tapered edge region has an average taper angle of not greater than 20 degrees relative to a length direction of the superstrate blank. In one embodiment, the coating of the superstrate can be applied by spin coating and may have an edge bead below a plane of the coating surface within the central region.