Organic Light Emitting Display Patterning via Infrared Photoresist
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Solution Overview
Problem
Existing methods for manufacturing organic light emitting display devices face challenges in achieving high resolution and large area applications due to limitations in mask manufacturing technology, such as mask sagging, material spread, and defects in the emission layer, which degrade device performance and characteristics.
Innovation Solution
A method involving the use of a photoresist film with a light expansion layer and a UV hardening resin, where infrared light is used to form patterns on a bank layer, preventing contact with the organic emission layer and facilitating the deposition of organic layers in sub-pixels, thereby minimizing damage and improving pattern formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fine metal mask process is used for patterning the emission layer, then the manufacturing process is simple, but the mask sags due to weight and material spread increases when applied to large area, making it difficult to achieve high resolution
Solution Approach 1:
A photoresist layer is introduced as an intermediary between the metal mask and the emission layer. The photoresist layer is coated on the metal mask, and a photoresist pattern is formed by irradiating with light through the metal mask. This photoresist pattern then serves as the actual patterning layer for the emission layer, preventing direct contact between the metal mask and emission layer, thereby eliminating mask sagging and material spread issues while maintaining high resolution and large area applicability
Solution Approach 2:
The traditional direct mechanical contact patterning using metal masks is replaced with an optical system. Instead of relying on mechanical precision of the metal mask itself, the process uses optical irradiation to transfer the pattern. The metal mask becomes an optical template rather than a direct mechanical barrier, eliminating the mechanical limitations of mask sagging and enabling high-resolution patterning on large areas
2Manufacturing precision
If an etching process is used to form the emission layer pattern, then the patterning is achieved, but direct contact between metal and etching solutions causes disconnection and etching depth control is difficult, decreasing device characteristic
Solution Approach 1:
The photoresist pattern serves as an intermediary protective layer between the emission layer and the etching solution. The emission layer is deposited only in areas where the photoresist pattern is removed, creating a physical barrier that prevents direct contact between the metal emission layer and etching solutions, thereby eliminating disconnection and improving etching depth control
Solution Approach 2:
The photoresist pattern is formed in advance before the emission layer deposition. This preliminary patterning step creates a template that guides subsequent material deposition and protects against etching damage, ensuring that the emission layer is formed only in the desired locations with proper depth control
3Manufacturing precision
If a lift-off process is used to form fine patterns, then the photoresist pattern can be removed to enable emission layer formation, but solvent and residual layer from strong adhesive strength cause defects in the emission layer, degrading display device characteristic
Solution Approach 1:
The photoresist layer acts as a protective intermediary between the emission layer and the lift-off process. By controlling the photoresist removal process, the emission layer is exposed only in the desired patterns without being exposed to harmful solvents and residual layers that would otherwise damage the emission layer structure
Solution Approach 2:
The strong adhesive strength of the photoresist, which initially appears as a disadvantage for complete removal, is converted into a benefit by allowing controlled, selective removal. The strong adhesion ensures complete coverage during deposition, while controlled removal creates clean patterns without damaging the emission layer, transforming the potential harm of strong adhesion into a benefit for pattern fidelity
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 enhances the emission efficiency and service life of organic light emitting display devices by preventing damage to the organic emission layer and enabling the formation of high-resolution patterns over large areas, thus improving manufacturing productivity.
Implementation Method 1
irradiating infrared (IR) light on the first photoresist film
Implementation Method 2
forming a first photoresist pattern by irradiating infrared (IR) light on the first photoresist film
Implementation Method 3
photoresist film with a light expansion layer and a UV hardening resin
Data Source
AI summary
Disclosed is a method of manufacturing an organic light emitting display device. The method include forming a driving thin film transistor and passivation layer on a substrate, forming a bank layer at a boundary portion between adjacent sub-pixels, on the passivation layer, laminating a first photoresist film on the bank layer, forming a first photoresist pattern by irradiating IR light on the first photoresist film in an area except a first sub-pixel, depositing a first organic emission layer in the first sub-pixel area exposed by the first photoresist pattern, removing the first photoresist pattern, laminating a second photoresist film on the bank layer, forming a second photoresist pattern by irradiating IR light on the second photoresist film in an area except a second sub-pixel, depositing a second organic emission layer in the second sub-pixel area exposed by the second photoresist pattern, and removing the second photoresist pattern.