In-line OLED Metrology for Dopant and Thickness Control
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Solution Overview
Problem
Current end-of-line metrology systems for OLED production face delays in detecting variations in dopant concentrations and layer thicknesses, leading to device performance issues and non-uniformity, due to the lag between deposition and characterization measurements, and are sensitive to vibrations in the deposition chambers.
Innovation Solution
An in-line process monitoring and control system that uses reflectometry and photoluminescence measurements within a transfer chamber between deposition chambers to provide real-time feedback on dopant concentrations and layer thicknesses, allowing for rapid adjustment of deposition processes and integration with existing hardware.
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 measurement delays occur and real-time process control is lost
Solution Approach 1:
The patent implements in-line metrology measurements during the deposition process itself, performing thickness and dopant concentration measurements on each layer immediately after deposition rather than waiting until end-of-line. This preliminary measurement approach enables real-time process control and eliminates the time delay inherent in post-deposition inspection systems
Solution Approach 2:
The system establishes a closed-loop feedback mechanism where in-line measurements of layer thickness and dopant concentration provide immediate information to control the deposition process. This feedback enables real-time adjustment of deposition parameters to maintain specification compliance, whereas end-of-line systems provide only post-hoc verification without process control capability
2Productivity
If in-line metrology measurements are performed during deposition, then real-time feedback is achieved, but the system becomes sensitive to vibrations in the deposition chamber
Solution Approach 1:
The patent extracts the metrology measurement function from the deposition chamber environment by performing measurements in a separate transfer chamber. This physical separation removes the measurement system from vibration sources associated with deposition operations, allowing high-speed in-line measurements without vibration sensitivity while maintaining real-time process monitoring capability
3Measurement precision
If complex end-of-line optical imaging and ellipsometry systems are used, then comprehensive substrate characterization is achieved, but system complexity and integration difficulty increase
Solution Approach 1:
The patent segments the metrology measurement functions into separate, specialized measurement systems within the transfer chamber - specifically separating thickness measurements from dopant concentration measurements. This segmentation allows each measurement function to be independently optimized and integrated, reducing overall system complexity compared to a single comprehensive end-of-line system while maintaining complete substrate characterization 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 solution enables near-real-time monitoring and control of OLED deposition, 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.