Halftone Mask With Semi-Transmitting Unit For Uniform Height
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Solution Overview
Problem
In the manufacturing of organic light emitting display devices, the use of halftone masks leads to height differences between pixel defining layers on either side of the pixel electrode, causing defects in subsequent processes such as organic and metal depositions, due to the varying thicknesses of underlying layers formed by these masks.
Innovation Solution
A halftone mask design featuring a first and second light blocking unit with a semi-transmitting unit in between, where the semi-transmitting unit reduces light intensity and is positioned adjacent to the second light blocking unit, ensuring the sum of the second and third lengths is greater than the first length, and the third length is inversely proportional to the first length, allowing for uniform height formation of underlying layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a halftone mask is used to pattern pixel defining layers, then the number of masks is reduced and productivity is enhanced, but height differences are generated between regions of pixel defining layers on both sides of the pixel electrode causing defects in subsequent processes
Solution Approach 1:
The mask structure is divided into different regions with different light transmission properties: first and second light blocking units (blocking light), a first semi-transmitting unit (partially transmitting light), and light transmitting units (fully transmitting light). This local differentiation of optical properties allows selective formation of pixel defining layers at different heights in different regions, resolving the height uniformity issue while maintaining single-mask productivity
Solution Approach 2:
The first semi-transmitting unit acts as an intermediary element between the light blocking units and light transmitting units. It partially transmits light to form intermediate-height pixel defining layers, creating a gradient effect that prevents height differences and ensures uniform underlying layer formation across the mask
2Productivity
If pixel defining layers are patterned using one mask, then productivity is enhanced, but height differences between regions cause masks to get loose during deposition processes
Solution Approach 1:
Different regions of the mask are designed with specific light transmission characteristics to form pixel defining layers with appropriate local heights. The light blocking units create higher regions that provide stable mask support, while light transmitting units create lower regions, preventing mask loosening during deposition
3Ease of manufacture
If pixel defining layers have height differences, then single-mask patterning is achieved, but defects occur in organic and metal deposition processes
Solution Approach 1:
The mask creates local variations in light transmission to form pixel defining layers at different heights where needed, but the controlled design ensures that underlying layers remain uniform. This local differentiation enables single-mask patterning while preventing deposition defects through proper height control
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 design ensures uniform heights of underlying layers, preventing defects in deposition processes and enhancing productivity and reducing manufacturing costs by maintaining consistent thicknesses across the pixel defining layers.
Implementation Method 1
The first semi-transmitting unit reduces intensity of light passing through the halftone mask
Implementation Method 2
a first light blocking unit having a first length and blocking light, a second light blocking unit having a second length and blocking light
Data Source
AI summary
Embodiments relate to halftone masks that can uniformly form the height of an underlying layer in two regions that are spaced apart from each other, a manufacturing method thereof, and a method for forming a film using the same. The halftone mask includes a first light blocking unit and a second light blocking unit, and a semi-transmitting unit that is disposed adjacent to the side of the second light blocking unit. The first and second light blocking units block light and are spaced apart from each other at a predetermined interval. The semi-transmitting unit is positioned at a side far from the first light blocking unit and reduces intensity of light. Sum of the second length of the second light blocking unit and the third length of the semi-transmitting unit is larger than the first length of the first blocking unit.