Laser Beam Contact Hole Formation for Thin OLED Cathodes
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Solution Overview
Problem
Conventional organic light-emitting display devices face issues with increased cathode resistance and IR drop due to the thickness of the cathode, leading to reduced brightness, which is addressed by incorporating an auxiliary electrode to decrease resistance.
Innovation Solution
A laser beam irradiation apparatus is used to form a contact hole between the auxiliary electrode and the cathode, employing a laser light source, controller, optical system, scanner, and F-theta lens to precisely control and direct the laser beam, reducing beam size and forming particles smaller than 20 nm, which are released as gas, allowing for a thinner cathode with reduced resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the cathode thickness is decreased to reduce resistance and IR drop, then brightness is improved, but the cathode becomes more fragile and difficult to manufacture
Solution Approach 1:
The cathode structure is segmented into multiple thin layers (e.g., LiF, Al, MgAg) rather than a single thick layer. This segmentation allows each layer to be deposited independently with precise thickness control, achieving low resistance while maintaining structural integrity and ease of manufacturing through standard vacuum deposition processes.
Solution Approach 2:
The invention changes the parameter of cathode thickness from a single thick layer to multiple thin layers with optimized individual thicknesses. By controlling the thickness of each sub-layer (e.g., 5-20 nm for LiF, 50-200 nm for Al), the overall resistance is reduced while maintaining manufacturability through precise deposition parameter control.
2Manufacturing precision
If a laser beam irradiation apparatus is used to form contact holes, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The invention replaces mechanical drilling or etching methods with laser beam irradiation to form contact holes. The laser system uses optical fields instead of mechanical tools, achieving superior precision in contact hole formation while the complexity is managed through software-controlled beam positioning and energy modulation.
Solution Approach 2:
The laser apparatus controls multiple parameters (beam energy, pulse duration, scanning speed, focal position) to achieve precise contact hole formation. By dynamically adjusting these parameters, the system achieves high manufacturing precision without requiring overly complex mechanical structures, as the control is achieved through programmable parameter modulation.
3Measurement precision
If multiple optical systems are arranged to control the laser beam, then beam precision is improved, but the system complexity increases
Solution Approach 1:
The optical system is designed with multi-functional components that serve multiple purposes. For example, the same optical components are used for both beam shaping and positioning, and the scanner serves both to direct the beam and to control the scanning pattern. This universality reduces the number of separate components needed, managing system complexity while maintaining high beam control precision.
Solution Approach 2:
The optical components are arranged in a nested or integrated configuration where smaller optical elements are positioned within or between larger ones. This nesting allows compact arrangement of multiple optical systems, reducing the overall footprint and inter-component complexity while maintaining the precision benefits of having multiple optical control stages.
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 method effectively decreases cathode resistance and IR drop, enhancing brightness by forming a contact hole using the laser beam irradiation apparatus, ensuring minimal contamination and improved manufacturing efficiency.
Implementation Method 1
forming a contact hole on the intermediate layer by irradiating a laser beam
Implementation Method 2
The controller may include an acusto optic modulator (AOM)
Implementation Method 3
an F-theta lens for diminishing a beam that has passed through the scanner
Data Source
AI summary
A laser beam irradiation apparatus includes a laser light source, a controller for controlling energy of light generated by the laser source, a first optical system for adjusting a shape of light that has passed through the controller, a scanner for adjusting the direction of light that has passed through the first optical system, and an F-theta lens for reducing a beam that has passed through the scanner.