OLED Pixel Defining Layer and Spacer Single Mask Patterning
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Solution Overview
Problem
The manufacturing process of organic light emitting display apparatuses is complex and costly due to the use of multiple masks in patterning the pixel defining layer and spacer, which increases production expenses.
Innovation Solution
The use of a closed-loop groove on the planarization layer allows for the formation of a pixel electrode and spacer using a single mask, simplifying the patterning process and reducing costs by utilizing the same material for the pixel defining layer and spacer, such as polyimide, and forming a passivation layer between the thin film transistor and planarization layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If two masks are used to pattern the pixel defining layer and spacer separately, then the patterning precision is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the pixel defining layer and spacer into a single integrated structure formed by one mask pattern. The mask includes both a light blocking unit (forming the pixel defining layer) and a semi-penetrating unit (forming the spacer) in a unified design, eliminating the need for separate patterning processes and reducing manufacturing complexity while maintaining precision
Solution Approach 2:
The single mask serves multiple functions simultaneously: it defines pixel boundaries through the light blocking unit and creates the spacer structure through the semi-penetrating unit. This multi-functional mask design consolidates what would traditionally require two separate masks, simplifying the manufacturing process while achieving both patterning objectives
2Ease of manufacture
If a half-tone mask with semi-penetrating unit is used, then the manufacturing process is simplified, but the manufacturing cost increases due to the complexity of the half-tone mask
Solution Approach 1:
The mask is segmented into distinct functional units: a light blocking unit for forming the pixel defining layer and a semi-penetrating unit for forming the spacer. This segmentation allows each unit to perform its specific function while being part of a single mask structure, avoiding the need for a complex half-tone mask design
3Reliability
If the pixel defining layer and spacer are formed using different materials and processes, then the functional requirements are met, but the manufacturing cost and process complexity increase
Solution Approach 1:
The patent uses the same material (organic insulating material) for both the pixel defining layer and the spacer, forming them in a single coating and patterning process. This homogeneous material approach eliminates the need for separate material deposition processes, reducing manufacturing cost and complexity while meeting the functional insulation requirements of both structures
Data Source
AI summary
An organic light emitting display apparatus including: a substrate; a thin film transistor formed on the substrate; a planarization layer formed on the substrate to cover the thin film transistor and comprising a closed-loop groove; a pixel electrode that contacts the thin film transistor and is formed on the planarization layer; a pixel defining layer formed to fill the closed-loop groove; a spacer formed on the planarization layer and disposed outside the pixel electrode; an organic light emitting layer formed on the pixel electrode; and an opposite electrode covering the organic light emitting layer.