Light Compensating Layer Dummy Holes for OLED Cracking
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Solution Overview
Problem
The organic light emitting display device experiences cracking in the light compensating layer due to stress generated at the boundary between the light compensating layer and the planarizing layer, caused by differences in thermal expansion coefficients, leading to reliability issues and color shift problems.
Innovation Solution
Formation of dummy holes in the light compensating layer to moderate stress, matching the area of the second drain contact hole, which exposes the planarizing layer and helps in balancing etch rates, thereby reducing thermal expansive force and preventing cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a light compensating layer is formed on the planarizing layer to prevent color shift, then display quality is improved, but stress is generated at the boundary due to thermal expansion coefficient differences causing cracking
Solution Approach 1:
The light compensating layer is segmented by forming dummy holes (first holes) within it, dividing the continuous layer into separate regions. This segmentation allows stress to be distributed and released at the hole boundaries rather than accumulating in the continuous layer, preventing cracking while maintaining the layer's color compensation function.
Solution Approach 2:
The light compensating layer is transformed into a porous structure by introducing dummy holes throughout its area. This porous configuration provides stress relief pathways while maintaining sufficient material continuity to perform the light compensation function, resolving the contradiction between preventing color shift and avoiding cracking.
2Manufacturing precision
If the light compensating layer is made continuous to ensure uniform color compensation, then display quality is improved, but stress concentration occurs leading to cracking
Solution Approach 1:
The continuous light compensating layer is segmented by introducing dummy holes, creating a discontinuous yet functionally continuous structure. The holes are positioned and sized to maintain uniform optical properties across the display area while providing stress relief, thus preserving color uniformity while improving stress resistance.
Solution Approach 2:
The dummy holes act as intermediary elements within the light compensating layer, serving as stress relief zones that mediate between the conflicting requirements of continuity (for color uniformity) and discontinuity (for stress resistance). The holes are strategically designed to maintain optical uniformity while providing mechanical relief.
3Reliability
If dummy holes are added to the light compensating layer to reduce stress, then cracking is prevented, but device complexity increases
Solution Approach 1:
The light compensating layer is segmented by forming dummy holes using standard photolithography and etching processes. This segmentation approach integrates seamlessly into existing manufacturing workflows, adding minimal complexity while effectively preventing cracking through stress distribution at the hole boundaries.
Solution Approach 2:
The dummy holes are designed with specific parameter ranges (size, spacing, distribution pattern) that optimize stress relief while maintaining manufacturing simplicity. By controlling these parameters within defined ranges, the solution achieves crack prevention without requiring complex fabrication processes, as the holes can be formed using conventional semiconductor manufacturing techniques.
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
The dummy holes effectively minimize stress between the light compensating and planarizing layers, preventing cracking and improving the reliability of the organic light emitting display device by concentrating thermal expansive force on the dummy holes, thus maintaining display quality.
Implementation Method 1
stress generated at the boundary between the light compensating layer and the planarizing layer, caused by differences in thermal expansion coefficients
Data Source
AI summary
The present application relates to a method for fabricating an organic light emitting display device, comprising: forming a drive thin film transistor on a substrate at a non-light emission region; forming a protective layer on the substrate; forming a color filter on the protective layer; forming a planarizing layer on a protective layer including the color filter; selectively removing the protective layer and the light compensating layer to form a first drain contact hole which exposes a drain electrode of the drive thin film transistor; forming a light compensating layer on the planarizing layer to have a second drain contact hole which exposes the first contact hole, and a dummy hole to expose the planarizing layer; and forming an organic light emitting element on the light compensating layer to be in contact with the drain electrode through the first and second drain contact holes.