Self-Aligned Trench Electrodes for High-Density Display Pixels
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Solution Overview
Problem
In head-mounted displays with ultrahigh definition, it is challenging to form electrodes within pixels due to the minute pixel pitches, which complicates the manufacturing process and reduces the aperture ratio of the display device.
Innovation Solution
A display device and manufacturing method that utilize self-aligned trenches to form electrodes without a particular mask, allowing for the use of high etching resistance materials like silver and minimizing light loss by reflecting light upward, while also reducing leakage current and maximizing the aperture ratio through strategic trench and bank design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electrode formation methods are used in ultrahigh definition head-mounted displays, then electrodes can be formed in patterns, but the manufacturing process becomes complex and aperture ratio decreases due to minute pixel pitches
Solution Approach 1:
The first electrode is formed to extend over the bank structure, and the light emitting layer is formed to extend over the first electrode. The bank itself serves as a self-aligned mask that automatically defines the boundaries of the first electrode and light emitting layer, eliminating the need for additional photolithography masks and complex alignment processes. This self-service approach simplifies the manufacturing process while maintaining high precision electrode formation in ultrahigh definition displays with minute pixel pitches.
2Manufacturing precision
If conventional electrode formation methods are used in ultrahigh definition head-mounted displays, then electrodes can be formed in patterns, but the aperture ratio decreases
Solution Approach 1:
The first electrode is extended onto the side surface of the bank, utilizing the vertical dimension of the bank structure. This three-dimensional electrode configuration allows the electrode to be formed without occupying additional horizontal space that would reduce the aperture ratio. The light emitting layer similarly extends over the first electrode on the bank side surface, maintaining pixel definition while maximizing the light-emitting area within the pixel pitch constraints of ultrahigh definition displays.
3Reliability
If high etching resistance materials like silver are used for the first electrode, then electrode performance improves, but etching process difficulty increases
Solution Approach 1:
The bank structure serves as a self-aligned mask that automatically defines the boundaries of the first electrode during the etching process. Because the first electrode is formed to extend over the bank and the light emitting layer extends over the first electrode, the bank itself provides the pattern definition without requiring additional photolithography masks. This eliminates the need to etch through multiple mask layers and simplifies the etching process, making it feasible to use high etching resistance materials like silver for the first electrode while maintaining ease of manufacture.
4Area of stationary object
If the bank top area is reduced to maximize aperture ratio, then pixel aperture increases, but electrode formation becomes more difficult
Solution Approach 1:
The first electrode is extended onto the side surface of the bank, utilizing the vertical dimension to accommodate the electrode structure. This allows the bank top area to be minimized for maximum aperture ratio while the first electrode still has sufficient area to form on the bank side surface and function properly. The light emitting layer similarly extends over the first electrode on the bank side surface, maintaining proper layer formation even with reduced bank top area. This three-dimensional configuration resolves the contradiction between maximizing aperture ratio and maintaining ease of electrode formation.
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
Simplifies the manufacturing process, reduces costs, minimizes light loss, and maximizes the aperture ratio of the display device by forming electrodes and light emitting layers in a self-aligned manner using trenches, effectively addressing the challenges of forming electrodes in high-definition displays.
Implementation Method 1
Because the first electrode and a light emitting layer may be self-aligned by trenches and may be formed by pixels. Accordingly, because the first electrode may be formed without using a particular mask, it is possible to simplify manufacturing processes and reduce process costs. Because the first electrode may be formed without performing any particular etching process, the first electrode can also be formed of a metal material having high etching resistance such as silver (Ag). Because the first electrode may also be formed on the side surface of the bank, light propagating to the bank can be reflected upward.
Data Source
AI summary
A display device includes: a substrate; a plurality of pixels on the substrate; an insulating film on the substrate; a bank on the insulating film, wherein the bank partitions the plurality of pixels; a first trench in the bank; and a second trench in the insulating film. A method of manufacturing a display device includes: forming a first lower metal layer and a second metal layer in patterns on a substrate; forming a first insulating film on the first lower metal layer and the second lower metal layer; forming a second insulating film on the first insulating film; forming a first trench to expose the second lower metal layer by performing a first etching process; and forming a second trench by performing a second etching process to etch the second lower metal layer exposed from a bottom of the first trench.