OLED Pixel Isolation Layer Single Mask Process
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Solution Overview
Problem
Conventional OLED devices face reliability issues due to moisture, oxygen, and contaminants, leading to deteriorated emission characteristics and complex manufacturing processes, particularly with the need for multiple mask processes to form passivation and pixel isolation layers.
Innovation Solution
A single mask process is used to form a laminated pixel isolation layer with an inorganic lower layer and an organic upper layer, along with insulating layers for pads and pad interconnection lines, simplifying the manufacturing process and enhancing the OLED device's longevity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passivation layer is formed between a thin film transistor and an anode electrode with an opening to expose a pad, then the lifetime of the organic EL device is extended and pad failures are prevented, but the manufacturing process becomes complicated due to multiple mask processes
Solution Approach 1:
The patent combines the passivation layer and pixel isolation layer into a single integrated structure formed through one mask process. The pixel isolation layer serves dual functions: it acts as a passivation layer protecting the thin film transistor and anode electrode, and simultaneously serves as the pixel isolation structure. This merging eliminates the need for separate mask processes for forming both layers, thereby simplifying the manufacturing process while maintaining the protective function that extends device lifetime and prevents pad failures.
Solution Approach 2:
The pixel isolation layer is designed to perform multiple functions: it provides passivation protection for the underlying thin film transistor and anode electrode, serves as an isolation structure for pixels, and enables the formation of both passivation and isolation features through a single mask process. This multi-functionality reduces the number of manufacturing steps while ensuring the reliability benefits of having a protective passivation layer.
2Manufacturing precision
If multiple mask processes are used to form passivation layer and pixel isolation layer openings, then precise positioning is achieved, but the manufacturing time and productivity are reduced
Solution Approach 1:
The patent merges the formation of passivation layer openings and pixel isolation layer openings into a single mask process. The pixel isolation layer is patterned to simultaneously define both the passivation opening (exposing the pad) and the pixel isolation features. This single-step patterning maintains precise positioning because the relative positions of all features are defined in one alignment operation, eliminating cumulative alignment errors from multiple processes while significantly reducing manufacturing time and increasing productivity.
3Reliability
If moisture, oxygen, and contaminants permeate into the organic EL device, then the emission characteristics deteriorate, but preventing permeation requires complex sealing structures
Solution Approach 1:
The pixel isolation layer is formed as a passivation layer before the organic EL device is assembled and sealed. This preliminary passivation layer provides immediate protection to the thin film transistor and anode electrode against moisture, oxygen, and contaminants during subsequent manufacturing steps and device assembly. By establishing this protective barrier early in the process, the need for overly complex sealing structures is reduced, as the passivation layer serves as a first line of defense that simplifies the overall sealing requirements while maintaining emission characteristics.
Data Source
AI summary
An organic light emitting display (OLED) device having a simple process of fabrication and improved lifetime and reliability, and a method of fabricating the same are disclosed. The OLED device comprises: a substrate; a sealing member which seals a plurality of pixels arranged on a pixel region; and a sealing material which bonds the substrate and the sealing member. Each of the pixels includes a thin film transistor disposed on the substrate, an EL device including a lower electrode connected to the thin film transistor, a pixel isolation layer exposing a portion of the lower electrode, an organic layer formed on at least the exposed portion of the lower electrode, and an upper electrode. A pad interconnection line of a pad interconnection region is covered by a first insulating layer, and a pad of a pad region is covered by a second insulating layer so as to expose a portion of the pad. The first insulating layer and the second insulating layer are formed of the same material as a lower layer of the pixel isolation layer.