OLED In-Line Metrology for Layer Thickness and Dopant Control
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Solution Overview
Problem
Existing OLED production lines face challenges in real-time monitoring and control of dopant concentrations and layer thicknesses due to delays in end-of-line metrology, leading to device performance issues and non-uniformity, with current methods being sensitive to vibrations and requiring significant time for feedback loops.
Innovation Solution
An in-line process monitoring and control system using reflectometry-photoluminescence and digital holographic microscopy methods within a transfer chamber between deposition chambers, providing rapid feedback and integrating with existing hardware to maintain vacuum conditions and minimize contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If end-of-line metrology systems are used to monitor OLED substrates after complete deposition, then device specifications can be verified, but real-time process control is lost and feedback delays occur
Solution Approach 1:
The patent implements in-line metrology measurements during the deposition process itself, performing thickness and dopant concentration measurements before the deposition sequence is complete. This preliminary measurement approach enables real-time process control and immediate feedback to the deposition system, eliminating the time loss associated with end-of-line inspection while maintaining measurement precision.
2Measurement precision
If optical imaging and ellipsometry techniques are used for end-of-line measurement, then layer thickness can be measured, but the systems are sensitive to vibrations and require significant time for feedback loops
Solution Approach 1:
The patent replaces vibration-sensitive mechanical ellipsometry systems with alternative measurement techniques that are less sensitive to vibrations. The in-line metrology system uses optical methods that can operate reliably in the vibration environment of the deposition chamber, substituting the problematic mechanical measurement system with a more robust solution that maintains measurement precision while improving reliability.
3Manufacturing precision
If multiple deposition chambers are used for sequential layer deposition, then OLED layer stack can be formed, but process monitoring and control become more complex
Solution Approach 1:
The patent implements a universal in-line metrology system that can measure multiple parameters (layer thickness, dopant concentration) across multiple deposition chambers using the same measurement principles. This multi-functional approach simplifies the overall monitoring system complexity by using consistent measurement methods throughout the sequential deposition process, while maintaining high manufacturing precision for the OLED layer stack.
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
Enables rapid in-line monitoring and control of OLED deposition processes, improving device performance, yield, and reducing production costs by providing immediate feedback on dopant concentrations and layer thicknesses, while being less sensitive to vibrations and easier to integrate with existing systems.
Implementation Method 1
At least one of the one or more sensors is positioned to receive reflections of the first light beam from the workpiece within the transfer chamber to perform reflectometry measurements and generate a thickness measurement of a layer on the workpiece from the reflectometry measurement
Implementation Method 2
a second light source to generate a second light beam to induce photoluminescence in the layer on the workpiece in the transfer chamber. At least one of the one or more sensors is positioned to receive emissions from the layer on the workpiece within the transfer chamber to perform photoluminescence measurements of the layer on the workpiece
Data Source
AI summary
An organic light-emitting diode (OLED) deposition system includes two deposition chambers, a transfer chamber between the two deposition chambers, a metrology system having one or more sensors to perform measurements of the workpiece within the transfer chamber, and a control system to cause the system to form an organic light-emitting diode layer stack on the workpiece. Vacuum is maintained around the workpiece while the workpiece is transferred between the two deposition chambers and while retaining the workpiece within the transfer chamber. The control system is configured to cause the two deposition chambers to deposit two layers of organic material onto the workpiece, and to receive a first plurality of measurements of the workpiece in the transfer chamber from the metrology system.