MEMS Actuator Vertical Actuation via Stacked Coil and Core
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Solution Overview
Problem
Current methods for forming MEMS actuators and relays lack an efficient approach for vertical actuation, which is essential for effective electrical pathway switching in micro-electromechanical systems.
Innovation Solution
A method involving a conventionally formed single-crystal silicon semiconductor wafer with a dielectric layer and metal interconnect structure, where a seed layer, copper, and magnetic materials are used to form a square coil and core member, along with a flexible member for vertical actuation, allowing for electromagnetic field-driven movement and ohmic contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional MEMS fabrication processes are used, then device compatibility is achieved, but vertical actuation capability is insufficient
Solution Approach 1:
The patent transitions from planar actuation to vertical actuation by stacking multiple functional layers (coil layer, core layer, flexible member layer, contact layer) in the vertical dimension. This dimensional change enables the actuator to generate vertical motion while maintaining compatibility with conventional planar MEMS fabrication processes.
Solution Approach 2:
The patent employs a nested structure where the core member is positioned within the coil, the flexible member is positioned above the core, and electrical contacts are integrated within the layered structure. This nesting approach maximizes space utilization and enables vertical actuation without increasing the device footprint.
2Force
If electromagnetic actuation is implemented, then actuation force is achieved, but processing temperature requirements increase
Solution Approach 1:
The patent optimizes electromagnetic actuation parameters including coil turn density, core material permeability, and air gap dimensions to achieve sufficient actuation force (100 μN) at lower processing temperatures. By carefully controlling these parameters, the design achieves effective actuation without requiring high-temperature processing that would be incompatible with backend CMOS processes.
3Reliability
If vertical actuation is achieved, then electrical pathway switching effectiveness is improved, but device structure complexity increases
Solution Approach 1:
The patent designs the layered structure to serve multiple functions simultaneously: the coil generates electromagnetic fields for actuation, the core concentrates magnetic flux, the flexible member provides both structural support and electrical connection, and the same layers participate in both actuation and switching functions. This multi-functionality reduces overall device complexity despite the vertical architecture.
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 efficient vertical actuation with forces in the range of 100 μN, suitable for low-impedance and high-impedance electrical pathway switching, compatible with conventional backend CMOS processes and requiring relatively low processing temperatures.
Implementation Method 1
where the mechanical member in the actuator moves in response to electromagnetic changes in the conditions of an electrical circuit
Implementation Method 2
A method involving a conventionally formed single-crystal silicon semiconductor wafer with a dielectric layer and metal interconnect structure, where a seed layer, copper, and magnetic materials are used to form a square coil and core member
Data Source
AI summary
A method of forming an actuator and a relay using a micro-electromechanical (MEMS)-based process is disclosed. The method first forms the lower sections of a square copper coil, and then forms a magnetic core member. The magnetic core member, which lies directly over the lower coil sections, is electrically isolated from the lower coil sections. The method next forms the side and upper sections of the coil, followed by the formation of an overlying cantilevered magnetic flexible member. Switch electrodes, which are separated by a switch gap, can be formed on the magnetic core member and the magnetic flexible member, and closed and opened in response to the electromagnetic field that arises in response to a current in the coil.