Micro LED Receiving Structure With Punch-Through Passivation
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Solution Overview
Problem
Integration and packaging issues, such as transfer wafer de-bonding and complex bonding/de-bonding steps, hinder the commercialization of micro devices like RF MEMS, LED display systems, and quartz-based oscillators in traditional micro device transfer technologies.
Innovation Solution
A method and structure for receiving micro devices on a substrate, involving a conductive layer, a micro LED device with a p-n diode and quantum well layer, and a thermoplastic or thermoset passivation layer, where the micro device is punched through and hardened for secure placement, allowing for efficient transfer and integration with electrostatic pick-up and heat-assisted bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional wafer bonding and transfer printing methods are used, then micro devices can be transferred from donor wafer to receiving wafer, but the process complexity increases due to multiple bonding and de-bonding steps
Solution Approach 1:
The patent extracts the de-bonding step from the traditional transfer process by using a sacrificial layer that automatically releases the device upon contact with the receiving wafer, eliminating the need for separate de-bonding operations and reducing process complexity
Solution Approach 2:
The patent introduces a sacrificial layer as an intermediary between the transfer wafer and receiving wafer, which facilitates device transfer by providing automatic release functionality and simplifying the overall bonding process
2Reliability
If transfer wafer de-bonding is performed after bonding, then devices can be released onto the receiving wafer, but integration and packaging issues arise
Solution Approach 1:
The patent performs preliminary action by pre-forming the sacrificial layer on the transfer wafer before device bonding, enabling automatic device release upon contact with the receiving wafer and eliminating subsequent de-bonding steps that cause integration and packaging issues
3Productivity
If elastomeric stamps with posts are used for transfer printing, then devices can be picked up and transferred, but the process requires intimate contact and van der Waals bonding which complicates the transfer mechanism
Solution Approach 1:
The patent replaces the complex mechanical elastomeric stamp system with a simpler sacrificial layer-based release mechanism, where device transfer is achieved through pre-formed release structures rather than intimate contact and van der Waals bonding
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 high-yield, cost-effective, and energy-efficient integration of micro devices into display and lighting systems, with significant power savings and improved reliability, facilitating the transfer of micro LED devices onto various substrates for heterogeneous integration.
Implementation Method 1
heating the passivation layer to a temperature above a glass transition temperature of the passivation layer but below a melting temperature of the passivation layer
Implementation Method 2
picking up the micro device with a transfer head and placing the micro device on the substrate
Data Source
AI summary
A method and structure for receiving a micro device on a receiving substrate are disclosed. A micro device such as a micro LED device is punched-through a passivation layer covering a conductive layer on the receiving substrate, and the passivation layer is hardened. In an embodiment the micro LED device is punched-through a B-staged thermoset material. In an embodiment the micro LED device is punched-through a thermoplastic material.