Partition Wall Formation via Overlapping Photomask Exposure
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Solution Overview
Problem
The existing methods for manufacturing organic electroluminescence (EL) display panels using division exposure struggle with noticeable misalignment of the partition wall at the photomask joint due to positional deviations, which cannot be sufficiently reduced by modifying photomask patterns.
Innovation Solution
A method involving the use of two photomasks with overlapping areas, where the boundary between exposure areas is set on a subpixel basis, allowing for the formation of a partition wall with reduced visibility of misalignment by narrowing the photomask overlapping area and simplifying the mask pattern, ensuring that any misalignment occurs within one pixel and is not noticeable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If division exposure is performed using multiple photomasks for large substrates, then the partition wall can be formed in multiple areas, but photomask positional deviation causes noticeable misalignment at photomask joints
Solution Approach 1:
The display area is divided into multiple division areas that are exposed sequentially using different photomasks. Each photomask is responsible for exposing a specific division area, allowing large substrates to be processed in manageable segments while maintaining overall pattern integrity
Solution Approach 2:
The photomasks are designed with overlapping exposure areas that extend beyond the nominal division boundaries. This overlapping in the spatial dimension creates a buffer zone that compensates for positional deviations, ensuring that patterns align correctly at the joints between division areas
2Manufacturing precision
If photomask patterns are modified to reduce misalignment visibility, then partition wall alignment improves, but the mask pattern becomes more complex
Solution Approach 1:
The photomask patterns are designed with different characteristics in different regions. The overlapping areas have extended patterns that provide alignment tolerance, while the central areas maintain the standard partition wall pattern. This local differentiation allows misalignment compensation without requiring complex patterns throughout the entire mask
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 effectively reduces pixel misalignment recognized due to photomask positional deviations, making the partition wall formation more accurate and visually unnoticeable, without increasing the number of reticles or exposures.
Implementation Method 1
exposed and developed using a photomask (reticle) having a predetermined mask pattern
Implementation Method 2
a positive photosensitive resin or a negative photosensitive resin is applied onto a substrate, and exposed and developed
Data Source
AI summary
A method of manufacturing a display panel includes: a first step of forming a partition wall layer above a substrate; a second step of exposing the partition wall layer using a first photomask that has a mask pattern corresponding to a blue opening; a third step of exposing the partition wall layer using a second photomask that has a mask pattern corresponding to a red opening and a green opening; a fourth step of forming a partition wall by removing the partition wall layer to form the red opening, the green opening , and the blue opening in the partition wall layer; and a fifth step of forming a light emitting layer in each opening.