Collimator Shadow Mask Deposition for AMOLED Resolution
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Solution Overview
Problem
Shadow-mask-based deposition techniques suffer from feature resolution limitations due to 'feathering' issues, where deposited material spreads laterally, restricting the density of device resolution and brightness in applications like AMOLED displays, especially in near-to-eye augmented and virtual reality applications.
Innovation Solution
A direct-patterning deposition system that filters vaporized atoms to a narrow range around the normal direction to the substrate surface using a collimator with high aspect ratio channels, reducing lateral deviation and mitigating feathering, allowing for high-resolution pattern deposition on substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If shadow-mask-based deposition is used to directly pattern material on substrate, then the need for photolithography and etching is eliminated, but feature resolution is diminished due to lateral spreading (feathering) of deposited material
Solution Approach 1:
A collimator structure is introduced as an intermediary component between the evaporation source and shadow mask. The collimator comprises multiple channels that guide vaporized atoms along defined paths, mediating the deposition process to reduce lateral spreading while maintaining direct patterning capabilities
Solution Approach 2:
The collimator is segmented into multiple discrete channels, each corresponding to a specific aperture in the shadow mask. This segmentation allows independent control and optimization of material flow paths for different regions, improving overall pattern fidelity and resolution
2Manufacturing precision
If large safety-margin gaps are included between subpixel regions to prevent overlap, then feathering issues are mitigated, but pixel fill factor is reduced and display brightness decreases
Solution Approach 1:
The collimator acts as an intermediary that controls the angular distribution of vaporized atoms, ensuring they travel along paths that pass through shadow mask apertures with minimal lateral deviation. This eliminates the need for large safety gaps while maintaining precise pattern separation
Solution Approach 2:
The system changes the angular distribution parameter of vaporized atoms by using the collimator structure to filter and direct atoms within a narrow angular range. This parameter change allows reduced spacing between features while maintaining pattern fidelity
3Adaptability or versatility
If color filters are deposited on top of OLED to create full color image, then color display is achieved, but up to 80% of emitted light is absorbed, requiring higher drive currents
Solution Approach 1:
The system performs preliminary patterning of color-emitting materials directly at the OLED layer using collimated shadow-mask deposition. By pre-defining the color regions before light emission, the need for subsequent color filters is eliminated, avoiding the 80% light absorption 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
The system achieves high-resolution direct deposition with reduced feathering, enhancing the density and brightness of displays by ensuring precise material placement, suitable for sensitive materials like organic light-emitting materials and various thin- and thick-film layers.
Implementation Method 1
In a high-vacuum environment, vaporized atoms will propagate in a generally ballistic fashion
Implementation Method 2
the collimator includes a plurality of channels, each channel having a height-to-width aspect ratio that defines a filtered angular range
Implementation Method 3
a source for providing a plurality of vaporized atoms
Data Source
AI summary
A direct-deposition system capable of forming a high-resolution pattern of material on a substrate is disclosed. Vaporized atoms from an evaporation source pass through an aperture pattern of a shadow mask to deposit on the substrate in the desired pattern. Prior to reaching the shadow mask, the vaporized atoms pass through a collimator that operates as a spatial filter that blocks any atoms not travelling along directions that are nearly normal to the substrate surface. As a result, the vaporized atoms that pass through the shadow mask exhibit little or no lateral spread (i.e., feathering) after passing through its apertures and the material deposits on the substrate in a pattern that has very high fidelity with the aperture pattern of the shadow mask. The present invention, therefore, mitigates the need for relatively large space between regions of deposited material normally required in the prior art, thereby enabling high-resolution patterning.