Temporary Electrode Testing for Micro-Device Display Repair
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Solution Overview
Problem
The challenge in micro device system integration is to efficiently test and repair defective micro devices transferred to a system substrate, especially when the electrode is deposited after placement, as it can damage the system and make testing and repair difficult due to floating contacts and the need to remove the electrode.
Innovation Solution
A method involving a temporary electrode for biasing and testing micro devices, capacitive coupling structures for defect identification, and a repair structure with fuses and spare circuits to disconnect defective devices and replace them with functional ones, using repair pads and defect mapping blocks to redirect data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temporary electrode is deposited after micro device placement to enable testing, then testing capability is improved, but the system becomes vulnerable to damage and requires complex removal procedures
Solution Approach 1:
The patent applies preliminary action by forming the temporary electrode structure before micro device placement. The electrode is deposited on the substrate prior to transferring micro devices, ensuring the testing infrastructure is already in place and eliminating the need for post-placement electrode deposition that could damage the system.
Solution Approach 2:
The patent uses an intermediary approach by introducing a removable dielectric layer between the temporary electrode and the micro devices. This dielectric layer acts as a mediator that protects the electrode during device placement and can be selectively removed to enable testing without damaging the underlying electrode structure or micro devices.
2Productivity
If redundant micro devices are used to increase yield, then production yield is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies parameter changes by modifying the electrical state of micro devices through the temporary electrode. By controlling voltage and current parameters through the electrode, defective devices can be identified and repaired or deactivated, allowing the system to achieve high yield without requiring redundant devices, thus reducing material consumption and cost.
3Stability of the object's composition
If the temporary electrode is removed after testing to prevent damage, then system integrity is improved, but testing and repair complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the temporary electrode structure into multiple independent regions or layers. This segmentation allows selective removal or deactivation of electrode portions corresponding to defective devices while maintaining the integrity of the overall system and simplifying the testing and repair process.
Solution Approach 2:
The patent extracts the testing function from the permanent system structure by using a separate, removable temporary electrode. This extracted electrode can be applied only when needed for testing and repair, then removed or deactivated, preventing permanent complexity in the system design while maintaining system integrity.
4Ease of manufacture
If floating contacts are present in the device to enable post-placement electrode connection, then ease of integration is improved, but testing difficulty increases due to floating contacts
Solution Approach 1:
The patent applies preliminary action by establishing complete electrical connections before the testing phase. The temporary electrode is configured to make contact with device contacts prior to final device placement and operation, ensuring that no floating contacts remain during testing. This preliminary connection establishment simplifies defect detection by providing stable electrical pathways for measurement.
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 effective testing and repair of micro devices without damaging the system, increasing yield and reducing costs by allowing for easy identification and replacement of defective devices while maintaining system integrity.
Implementation Method 1
capacitive coupling structures for defect identification
Data Source
AI summary
What is disclosed are structures and methods for testing and repairing emissive display systems. Systems are tested with use of temporary electrodes which allow operation of the system during testing and are removed afterward. Systems are repaired after identification of defective devices with use of redundant switching from defective devices to functional devices provided on repair contact pads. Time varying signals coupled to a capacitor are used as well.