Patterning Light-Emitting Devices Using Segmented Masking Films
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Solution Overview
Problem
Existing methods for patterning light-emitting materials on substrates face challenges such as low resolution, high particulate contamination, damage to underlying layers, and increased manufacturing costs, particularly when scaling to large substrates and using delicate organic materials like OLEDs.
Innovation Solution
A method involving multiple masking films with segmented opening portions, where each opening portion is used to deposit specific materials, and the films are registered and removed to prevent contamination and damage, allowing for precise patterning and iterative deposition without exposing previously deposited materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If shadow-masks are used for patterning organic light-emitting materials, then material deposition can be achieved, but resolution is reduced and particulate contamination increases due to mask flaking and thermal expansion
Solution Approach 1:
The patent replaces the mechanical shadow-mask system with a photolithographic system using photoresist layers and UV exposure. This substitution eliminates the mechanical contact and thermal expansion issues of shadow-masks, thereby reducing particulate contamination and improving patterning resolution through optical projection methods.
Solution Approach 2:
The patent changes the state of the masking material from solid shadow-mask to photoresist layer that can be selectively removed. By controlling the solubility parameters of the photoresist in specific solvents, the patent enables precise pattern transfer without the contamination issues of traditional shadow-masks.
2Ease of manufacture
If shadow-masks are used for patterning, then material deposition is enabled, but device complexity and manufacturing cost increase due to frequent mask fabrication, cleaning, and replacement
Solution Approach 1:
The patent employs disposable photoresist layers that are applied, patterned, and removed in each manufacturing cycle. These photoresist layers are much cheaper and easier to handle than reusable shadow-masks, eliminating the need for complex mask fabrication, cleaning, and replacement procedures.
Solution Approach 2:
The patent segments the patterning process into distinct steps: photoresist application, UV exposure through the mask, development, and removal. This segmentation allows each step to be optimized independently and simplifies the overall manufacturing process compared to managing reusable shadow-masks.
3Reliability
If shadow-masks are used for patterning, then material deposition can proceed, but underlying layers are damaged due to mask alignment issues and mechanical contact
Solution Approach 1:
The patent introduces a photoresist layer as an intermediary between the shadow-mask and the underlying organic materials. This photoresist layer absorbs the mechanical and thermal stresses, preventing direct contact damage to the delicate organic layers while still allowing precise pattern transfer through UV exposure.
Solution Approach 2:
The patent applies the photoresist layer and forms the pattern before depositing the light-emitting materials. This preliminary patterning ensures that the underlying layers are protected from damage during subsequent deposition steps, as the photoresist serves as a sacrificial protective layer.
4Adaptability or versatility
If color filters are used with broad-band emitter to create full-color display, then light emission is achieved, but manufacturing cost and process complexity increase
Solution Approach 1:
Instead of using a broad-band emitter with color filters to create colors, the patent inverts the approach by using separate patterned red, green, and blue light-emitting materials directly on the substrate. This eliminates the need for color filters and simplifies the manufacturing process while maintaining full-color display capability.
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 enhances resolution, reduces damage to underlying layers, minimizes particulate contamination, and lowers manufacturing costs while enabling large-scale patterning of light-emitting devices with improved efficiency.
Implementation Method 1
The opening portions are removed, for example, by ablation
Implementation Method 2
depositing materials over the substrate in the first locations
Implementation Method 3
For small-molecule organic materials, such patterned deposition is done by evaporating materials
Implementation Method 4
mechanically locating a first masking film over a substrate
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
A method of patterning a substrate by mechanically locating a first masking film over the substrate; removing one or more first opening portions in first locations in the first masking film to form one or more first masking portions in the first masking film. First materials are deposited over the substrate in the first locations to form first patterned areas before mechanically locating a second masking film over the substrate and first masking portions. One or more second opening portions are removed from second locations, different from the first locations, in both the second masking film and the first masking portions to form one or more second masking portions. Second materials are deposited over the substrate in the second locations to form second patterned areas.