Dual Substrate MEMS Plate Switch for Compact RF Design
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Solution Overview
Problem
Existing microelectromechanical systems (MEMS) switch devices, particularly electrostatic cantilevered designs, face challenges with substrate fragility and limited flexibility, leading to susceptibility to damage during fabrication and restricted compactness due to the need for a certain length of cantilevered beam for sufficient flexibility.
Innovation Solution
The development of an electrostatic MEMS plate switch using dual substrates, where a deformable plate with shunt bars is formed on one substrate and electrical contacts on another, allowing for a more compact design with adjustable restoring forces and enhanced durability through spring beams and hermetic sealing, which reduces the impact of vibrations and environmental interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a thin moveable substrate is used to enable electrostatic deflection, then the substrate can be actuated by electrostatic force, but it becomes delicate and susceptible to damage from contact during or after fabrication
Solution Approach 1:
The device is divided into two separate substrates: a fixed substrate that remains thick and rigid for durability, and a moveable substrate that is thin and flexible for electrostatic actuation. This segmentation allows each substrate to be optimized for its specific function without compromising the other.
Solution Approach 2:
A release layer is introduced as an intermediary between the fixed and moveable substrates. This release layer enables the moveable substrate to be fabricated and released without direct contact damage to the thin structure, serving as a protective mediator during the fabrication process.
2Ease of operation
If a cantilevered beam design is used to provide flexibility, then the beam can deflect sufficiently for switching, but the device requires a certain length that restricts compactness
Solution Approach 1:
The design transitions from a one-dimensional cantilevered beam to a two-dimensional deformable plate structure. This dimensional change allows the plate to achieve sufficient flexibility and deflection capability while occupying a smaller footprint area, thereby improving device compactness.
3Duration of action of moving object
If the top substrate is made flexible for moveability, then electrostatic deflection is enabled, but the substrate becomes susceptible to damage from contact
Solution Approach 1:
The device is divided into two separate substrates: a fixed substrate that remains thick and rigid for durability, and a moveable substrate that is thin and flexible for electrostatic actuation. This segmentation allows each substrate to be optimized for its specific function without compromising the other.
Solution Approach 2:
A release layer is introduced as an intermediary between the fixed and moveable substrates. This release layer enables the moveable substrate to be fabricated and released without direct contact damage to the thin structure, serving as a protective mediator during the fabrication process.
4Ease of manufacture
If a single substrate is used for the switch structure, then fabrication is simpler, but the design lacks versatility for multiple switches and compact arrangements
Solution Approach 1:
The device is divided into two separate substrates: a fixed substrate that remains thick and rigid for durability, and a moveable substrate that is thin and flexible for electrostatic actuation. This segmentation allows each substrate to be optimized for its specific function without compromising the other.
Solution Approach 2:
The deformable plate design serves multiple functions: it provides the moveable structure for switching, supports multiple contact points for multi-pole switches, and enables compact arrangements of multiple switches on a single device footprint, thereby achieving versatility.
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 approach enables a more compact, robust, and versatile MEMS switch capable of operating across a wide frequency range (DC to 10 GHz) with improved resistance to vibrations and environmental factors, allowing for multiple switches on a single plate and reduced contact resistance.
Implementation Method 1
the electrostatic force may cause it to deflect
Implementation Method 2
The electrostatic plate and the electrostatic electrode form a capacitor
Implementation Method 3
the stiffness of the restoring force on the plate may no longer be determined by the plate dimensions, but instead may be determined by spring beams which support the deformable plate
Data Source
AI summary
Systems and methods for forming an electrostatic MEMS plate switch include forming a deformable plate on a first substrate, forming the electrical contacts on a second substrate, and coupling the two substrates using a hermetic seal. The deformable plate may have at least one shunt bar located at a nodal line of a vibrational mode of the deformable plate, so that the shunt bar remains relatively stationary when the plate is vibrating in that vibrational mode. A hermetic seal may be made around the device with a larger, secondary enclosure. Electrical access to the deformable plate may be accomplished by an electrical path which is independent of the seal. The electrical path may include a via through the first substrate or the second substrate, or a flash deposited on an external region of the switch.