Organic Light Emitting Display Sacrifice Layer Oxidation Control
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Solution Overview
Problem
In organic light emitting displays, the oxidation of cathode electrodes during formation reduces electron injection efficiency, and differences in thin film heights can cause short circuits or open circuits between cathode electrodes.
Innovation Solution
The use of sacrifice layers and bank layers in the formation of organic light emitting displays, where the sacrifice layers are formed within the range of the bank layers or photoresist, to expose portions of the connection electrodes and facilitate the formation of lower and upper electrodes, preventing oxidation and height differences that can lead to circuit issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cathode electrode is formed directly on the transistor, then the structure is simple, but the cathode electrode is oxidized during formation, reducing electron injection efficiency
Solution Approach 1:
A sacrifice layer is introduced as an intermediary between the cathode electrode and the transistor. This sacrifice layer prevents direct contact between the cathode electrode and oxidizing environments during formation, thereby preventing oxidation and maintaining electron injection efficiency. The sacrifice layer is later removed to expose the connection electrode, resolving the contradiction by adding a temporary protective element.
Solution Approach 2:
The sacrifice layer is formed in advance before the cathode electrode is deposited. This preliminary action creates a protective barrier that prevents oxidation during the subsequent cathode electrode formation process. By performing the protective action beforehand, the cathode electrode can be formed without direct exposure to oxidizing conditions.
2Reliability
If the cathode electrode is formed without height control, then the manufacturing process is simple, but short circuits occur between cathode electrodes or open circuits occur in the anode electrode
Solution Approach 1:
The sacrifice layer acts as a height reference and protective intermediary during the formation of the cathode electrode. It ensures that the cathode electrode is formed at the correct height and position, preventing short circuits between adjacent cathode electrodes and open circuits in the anode electrode. The sacrifice layer is later removed to expose the properly positioned connection electrode.
Solution Approach 2:
The sacrifice layer is positioned specifically at critical locations where height control is needed, such as at the boundaries between adjacent subpixels. This localized quality control prevents short circuits between cathode electrodes while maintaining the overall simplicity of the manufacturing process.
3Ease of manufacture
If the undercut pattern depth is increased to expose the connection electrode, then the connection electrode is properly exposed, but the manufacturing complexity and potential for defects increase
Solution Approach 1:
Instead of creating a deep undercut pattern that requires high precision, the sacrifice layer is used to provide the necessary exposure. The sacrifice layer is formed slightly beyond the minimum required extent (excessive action), ensuring complete exposure of the connection electrode without requiring precise deep etching. This approach reduces manufacturing precision requirements while achieving the desired exposure.
Data Source
AI summary
An organic light emitting display and a method of manufacturing the same are disclosed. The organic light emitting display includes a transistor including a gate, a source, and a drain on a substrate, a connection electrode that is positioned on the transistor to be connected to the source or the drain, a first sacrifice layer that is positioned on the connection electrode to expose a portion of the connection electrode, a second sacrifice layer that is positioned on the first sacrifice layer to expose a portion of the connection electrode, a lower electrode on the connection electrode and the second sacrifice layer, an organic light emitting layer on the lower electrode, and an upper electrode on the organic light emitting layer. The first sacrifice layer is formed within range of a length of the second sacrifice layer inside the second sacrifice layer.