Maskless Display Layer Structure for Larger Active Area
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Solution Overview
Problem
Conventional display devices have limited display areas due to the use of masks for forming light emitting layers, which results in the formation of dummy pixels and shadows, thereby restricting the enlargement of the display area and affecting the quality and productivity of the devices.
Innovation Solution
A display device and method where the light emitting layer, upper electrode, and insulating layer are formed without using a mask, allowing the second and fourth sub-metal layers to protrude and form undercut structures, eliminating the need for dummy pixels and shadows, and enhancing the adhesiveness of the insulating layers to prevent peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mask is used to form the light emitting layer, then the light emitting layer can be formed with defined patterns, but the display area is limited due to formation of dummy pixels and shadows
Solution Approach 1:
The patent removes the mask from the manufacturing process entirely. The light emitting layer is formed without a mask by controlling the deposition process so that the layer is deposited only on the lower electrode and not on the surrounding areas, eliminating the need for dummy pixels and shadows that limit display area.
Solution Approach 2:
Instead of using a mask to define where the light emitting layer should be deposited (positive definition), the patent inverts the approach by forming the light emitting layer without a mask and allowing it to be deposited only where needed through controlled deposition angles and sacrificial layer removal, thereby eliminating the mask's physical constraints.
2Manufacturing precision
If a mask is used to form the light emitting layer, then patterning can be achieved, but productivity and quality are reduced due to dummy pixels and shadows
Solution Approach 1:
The mask is completely removed from the process. Patterning is achieved through a different mechanism: the sacrificial layer is formed first, then the light emitting layer is deposited at a specific angle that allows it to be formed only on the lower electrode. Afterward, the sacrificial layer is removed, leaving the desired pattern without any mask-related limitations on productivity or quality.
Solution Approach 2:
The mechanical mask system is replaced with a deposition angle control mechanism. Instead of using a physical mask to block deposition, the patent controls the deposition angle so that material is deposited only on surfaces facing the deposition source, eliminating the mask and its associated productivity and quality issues.
3Ease of manufacture
If the insulating layer is deposited on a flat surface, then deposition is simple, but peeling occurs due to insufficient adhesiveness
Solution Approach 1:
The patent creates an undercut structure with curved surfaces by depositing the light emitting layer and metal layers at oblique angles. This forms protruding portions of the sacrificial layer with non-planar surfaces. When the insulating layer is deposited over these curved surfaces, the increased surface area and mechanical interlocking prevent peeling, improving adhesion while maintaining deposition simplicity.
Solution Approach 2:
The patent transitions from a two-dimensional flat surface to a three-dimensional undercut structure with vertical and inclined surfaces. This dimensional change creates a mechanical interlock between the insulating layer and the underlying structure, preventing peeling while keeping the deposition process simple.
4Reliability
If multi-layer metal structure with protruding portions is formed, then adhesion is improved, but manufacturing complexity increases
Solution Approach 1:
The sacrificial layer is formed in advance with specific protruding portions that will create the undercut structure. The light emitting layer and metal layers are then deposited at controlled angles to form the multi-layer structure with protruding portions. This preliminary preparation of the sacrificial layer simplifies the overall process by establishing the adhesion-enhancing structure before the final layers are deposited.
Solution Approach 2:
The sacrificial layer acts as an intermediary structure that is formed first to create the undercut geometry. It enables the formation of the adhesion-enhancing multi-layer structure without requiring direct complex patterning of the final metal layers. The sacrificial layer is later removed, leaving the desired structure without the complexity of directly forming it.
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 increases the quality and productivity of the display device by enlarging the display area and reducing the peeling phenomenon of the insulating layers, resulting in improved performance and efficiency.
Implementation Method 1
A wet etching is performed on the preliminary metal layer and the first sacrificial layer exposed by the second opening
Implementation Method 2
The preliminary first light emitting layer may be deposited at a first deposition angle, and the preliminary first upper electrode may be deposited at a second deposition angle
Data Source
AI summary
A display device includes a substrate. A lower electrode is disposed on the substrate. A metal layer is disposed on the substrate and exposes at least a portion of the lower electrode. A light emitting layer is disposed on the lower electrode and the metal layer. An upper electrode is disposed on the light emitting layer. An insulating layer is disposed on the upper electrode.