OLED Planarization Layer Roughness Reduction
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Solution Overview
Problem
The dry etching process in the fabrication of organic light emitting diode (OLED) display devices causes damage to the planarization layer, leading to increased roughness, which results in decreased reflectivity and variation of color coordinates due to scattered reflection.
Innovation Solution
The method involves annealing and curing the planarization layer after forming a first extension of a via-hole, followed by dry etching the passivation layer to form a second extension of the via-hole, and providing an ashing treatment and surface treatment to the planarization layer to reduce roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dry etching is performed on the passivation layer using the planarization layer as a mask, then via-holes are formed to connect the pixel electrode to the source/drain electrodes, but the planarization layer becomes damaged and rough due to direct contact with plasma
Solution Approach 1:
An additional mask layer (photoresist or hard mask) is introduced between the planarization layer and the plasma during dry etching. This intermediary layer protects the planarization layer from direct plasma damage while still allowing precise via-hole formation through controlled etching of the mask layer and underlying passivation layer.
Solution Approach 2:
The planarization layer undergoes preliminary annealing treatment before the dry etching process. This pre-treatment strengthens the planarization layer's resistance to plasma damage, preventing roughness formation during subsequent via-hole etching while maintaining the ability to form precise via-holes.
2Productivity
If the planarization layer is directly exposed to plasma during dry etching, then via-holes are formed, but the roughness of the planarization layer increases leading to scattered reflection
Solution Approach 1:
A sacrificial mask layer is placed between the plasma and the planarization layer during dry etching. This mask layer absorbs the plasma damage, allowing efficient via-hole formation through the passivation layer while the planarization layer remains protected and maintains its surface flatness.
Solution Approach 2:
The plasma that would normally damage the planarization layer is redirected to etch a sacrificial mask layer instead. The harmful plasma energy is converted into a useful function of removing the mask material, while the planarization layer emerges undamaged and smooth.
3Manufacturing precision
If annealing and curing treatments are applied to the planarization layer, then roughness is reduced and reflectivity is improved, but the fabrication process time increases
Solution Approach 1:
The annealing and curing treatments for the planarization layer are combined with existing fabrication process steps, such as integrating them with the passivation layer formation or pixel electrode deposition process. This consolidation reduces the total process time while still achieving the desired surface flatness and reflectivity improvement.
Solution Approach 2:
The annealing temperature, duration, and atmospheric conditions are optimized to achieve the required surface flatness and reflectivity in the shortest possible time. By adjusting these parameters, the process maintains high manufacturing precision while minimizing time loss.
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 effectively reduces the roughness of the planarization layer, thereby minimizing issues such as decreased reflectivity and color coordinate variation in OLED display devices.
Implementation Method 1
annealing and curing the planarization layer after forming a first extension of a via hole
Implementation Method 2
The via-hole may be dry etched using the planarization layer as a mask
Implementation Method 3
providing an ashing treatment to the planarization layer
Data Source
AI summary
In a method of fabricating organic light emitting diode display, a planarization layer is annealed, cured, provided with an ashing treatment, and surface-treated to reduce roughness of the planarization layer. Therefore, it is possible to improve reduce problems such as a decrease in reflectivity and variation of color coordinates of the organic light emitting diode display due to the roughness of the planarization layer.