Interdigitated Spring Electrodes for Micro Device Transfer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The commercialization of miniature devices such as RF MEMS microswitches and LED display systems is hindered by the difficulties and costs associated with manufacturing processes, particularly in transferring miniaturized devices from one wafer to another, where existing technologies like electrostatic transfer with electrostatic transfer heads face challenges in achieving efficient and reliable device transfer.
Innovation Solution
The development of compliant electrostatic transfer heads with interdigitated spring electrodes, which include a base substrate and a plurality of deflectable spring electrodes with mesa structures aligned in a row, providing a larger contact surface and increased electrostatic force for efficient transfer of microscale devices by applying a pull-in voltage to generate grip pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If traditional electrostatic transfer heads are used, then device transfer is achieved, but the contact surface area is insufficient and transfer reliability is compromised
Solution Approach 1:
The transfer head is divided into multiple interdigitated spring electrodes instead of using a single rigid electrode structure. Each spring electrode contains multiple mesa structures that can independently deflect and contact the micro device, increasing the total contact surface area while maintaining reliability through distributed contact points
Solution Approach 2:
The spring electrodes are designed to be deflectable rather than rigid, allowing them to dynamically adapt to the micro device surface during transfer. The spring arms can bend and the mesa structures can deflect into the cavity to make contact, providing compliance that ensures reliable contact across varying device geometries
2Reliability
If the contact surface is increased to improve transfer reliability, then more mesa structures are needed, but the device complexity increases
Solution Approach 1:
Multiple spring electrodes with mesa structures are merged into an interdigitated configuration where they share common support structures and bus bars. The spring platforms are interdigitated and share common support, reducing the overall structural complexity while maintaining multiple contact points for reliable transfer
3Ease of operation
If spring electrodes are made more compliant to improve contact, then the structural strength decreases, but if made stronger, then compliance is reduced
Solution Approach 1:
The spring electrodes exhibit different mechanical properties at different locations: the spring arms and support structures are designed with appropriate thickness and material properties to provide compliance where needed (at the mesa structure tips) while maintaining structural strength in the support regions. The mesa structures themselves are localized contact points that can deflect independently
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 the efficient transfer of microscale devices like diodes, LEDs, and MEMS by providing a compliant contact surface and sufficient electrostatic force, facilitating high transfer rates and integration into heterogeneous systems, from a donor wafer to a receiving substrate, overcoming previous manufacturing challenges.
Implementation Method 1
applying a pull-in voltage to generate grip pressure
Data Source
AI summary
A compliant electrostatic transfer head and array are described. In an embodiment a compliant electrostatic transfer head includes a base substrate, and a plurality of interdigitated spring electrodes that are deflectable together into a cavity toward the base substrate. Each spring electrode includes mesa structure, and the mesa structures of the plurality of interdigitated spring electrodes are aligned.