MEMS Actuator Post-Processing for Large Angle Beamsteering
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Solution Overview
Problem
Current MEMS devices for large angle beamsteering lack the capability to achieve both high tip/tilt angles and piston motion while maintaining a high fill-factor, which is essential for applications such as optical scanning and medical imaging, as most designs either have limited angles or low fill-factors.
Innovation Solution
The development of a post-processing method for MEMS actuator elements, involving the deposition of a second dielectric layer and removal of a sacrificial layer to enhance beam bending moments, allowing for large angle deflections and scalable arrays with high fill-factors, suitable for various applications including EO/IR beamsteering and medical endoscopy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional MEMS designs are used, then manufacturing simplicity is maintained, but tip/tilt angle and piston motion capability are limited to ±30° or ±20°
Solution Approach 1:
The device is divided into multiple independent actuators (first and second actuators) that can be controlled separately. Each actuator consists of distinct layers (sacrificial layer, first dielectric layer, second dielectric layer, metallic layer) that can be processed independently through selective release and deposition, enabling complex motion capabilities while maintaining manufacturing simplicity
Solution Approach 2:
The invention transitions from planar 2D deflection to 3D motion by adding out-of-plane piston motion capability. The sacrificial layer release mechanism enables the metallic layer to deflect not only in-plane (tip/tilt) but also out-of-plane (piston), achieving large angle beamsteering with both tip/tilt and piston motion simultaneously
2Manufacturing precision
If large tip/tilt angles are achieved, then beamsteering capability is improved, but fill-factor decreases below 90%
Solution Approach 1:
The invention uses thin film structures (metallic layer, dielectric layers) that can be deposited conformally over the substrate. These thin films enable large angle deflection without requiring bulky mechanical structures, maintaining high fill-factor by minimizing the footprint of non-active areas while achieving >90% fill-factor with large tip/tilt and piston motion
Solution Approach 2:
The sacrificial layer is deposited and patterned in advance to define the release regions before the metallic and dielectric layers are formed. This preliminary structuring allows controlled release and deflection of specific regions, enabling large angle beamsteering while maintaining high fill-factor through precise spatial control of the actuation regions
3Area of moving object
If high fill-factor arrays are created, then scanning coverage is improved, but tilt angle is reduced to less than 5°
Solution Approach 1:
The invention changes the physical parameters of the actuator structure by adding multiple dielectric layers with different properties and thicknesses, and by using selective sacrificial layer release. This enables the system to achieve both high fill-factor and large tilt angles by controlling the mechanical properties (stress, stiffness) of the multi-layer structure rather than relying on geometric constraints
Solution Approach 2:
The device uses composite multi-layer structures combining sacrificial layer, first dielectric layer, second dielectric layer, and metallic layer. Each layer contributes different mechanical and electrical properties, allowing the system to achieve high fill-factor and large tilt angle simultaneously through material property optimization rather than geometric compromise
4Device complexity
If single element actuators are used, then device simplicity is maintained, but both large tip/tilt angle and piston motion capabilities are not achieved simultaneously
Solution Approach 1:
The actuator is segmented into functionally distinct layers (sacrificial, first dielectric, second dielectric, metallic) that can be independently controlled. This segmentation allows different regions of the same actuator to perform different functions (tip/tilt vs. piston motion) simultaneously, achieving versatile motion capability without requiring multiple separate actuators
Solution Approach 2:
The single actuator element is designed to perform multiple functions: it can produce tip/tilt motion through differential deflection of the metallic layer, piston motion through out-of-plane displacement, and can be controlled independently or in arrays. This multi-functionality is achieved through the multi-layer structure that responds differently to electrical actuation in various modes
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 large angle beamsteering with high scanning speeds and high fill-factors (>90%), making it suitable for replacing gimbal-based systems and enhancing imaging and communication systems by allowing for multi-beam scanning at low voltage.
Implementation Method 1
depositing a second dielectric on a portion of the metallic or conductive layer at the distal end
Implementation Method 2
the sacrificial layer is removed
Data Source
AI summary
A method of post-processing an actuator element is presented. The method begins by receiving a fabricated actuator element including a metallic layer contacting a substrate, sacrificial layer proximate the metallic layer, and a first dielectric layer on the sacrificial layer. The metallic layer has an end proximal to and contacting at least part of the substrate and a distal end extending over the first dielectric layer. A second dielectric is deposited on a portion of the metallic layer at the distal end. And, the sacrificial layer is removed.