MEMS Micromechanical Arm Array With Protrusions for Impact Resistance
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Solution Overview
Problem
MEMS devices, particularly those used in sensor-shift optical image stabilization systems, face challenges with impact resistance and repairability due to the microscale or nanoscale dimensions of their components, such as micromechanical arms, which are difficult to replace if damaged.
Innovation Solution
The implementation of a micromechanical arm array with protrusions at the top of each arm, encapsulated by protection films, and connected by a metal connection structure. This design enhances impact resistance by creating additional space for movement and improves conductivity and sensitivity by increasing the contact area between the metal connection and the micromechanical arms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If micromechanical arms are made at microscale or nanoscale dimensions, then device miniaturization and integration are achieved, but impact resistance and repairability deteriorate
Solution Approach 1:
The micromechanical arm is divided into multiple discrete arms arranged in an array, where each arm is independently supported by its own protrusion. This segmentation allows individual arms to move independently and reduces the impact of damage to any single arm on the overall device functionality.
Solution Approach 2:
Protrusions are added in the vertical dimension extending upward from the substrate surface. This vertical dimension provides additional space for micromechanical arm movement and creates clearance that prevents arms from contacting the substrate during actuation, thereby improving impact resistance.
2Volume of moving object
If micromechanical arms are made at microscale or nanoscale dimensions, then device miniaturization is achieved, but ease of repair deteriorates
Solution Approach 1:
The array of independently supported micromechanical arms allows for modular functionality. If one arm fails, the others continue to operate, providing inherent redundancy that simplifies the repair strategy by eliminating the need to repair every component for the device to remain functional.
Solution Approach 2:
The protrusion structure provides self-alignment and automatic positioning for micromechanical arms. The geometric constraints of the protrusions guide the arms into correct positions during assembly and operation, reducing the need for complex alignment procedures during repair or replacement.
3Reliability
If protrusions are added to micromechanical arms, then impact resistance improves, but device complexity increases
Solution Approach 1:
The protrusions serve multiple functions simultaneously: they provide vertical support for micromechanical arms, enable independent arm movement, create clearance from the substrate, and facilitate electrical connection. This multi-functionality reduces the need for separate components, thereby managing complexity while improving reliability.
Solution Approach 2:
The protrusion integrates the support, positioning, and electrical connection functions into a single structural element. By merging these functions that would otherwise require separate components, the design improves impact resistance without proportionally increasing device complexity.
4Reliability
If metal connection structure contact area with micromechanical arms is increased, then conductivity and sensitivity improve, but manufacturing precision requirements increase
Solution Approach 1:
The metal connection structure is designed to make contact with micromechanical arms at multiple points along the protrusion surface. This distributed contact creates equipotential zones that ensure uniform electrical connection and reduce sensitivity to minor misalignments, thereby improving conductivity without requiring extremely tight manufacturing tolerances.
Solution Approach 2:
The contact interface is extended into the vertical dimension along the protrusion surface. Instead of relying on a single-point contact that would require high precision, the connection is distributed along the vertical extent of the protrusion, providing tolerance to lateral misalignment while maintaining good electrical contact.
Data Source
AI summary
A method comprises: providing a substrate comprising a first trench; forming an etch stop layer on the substrate; forming a silicon sacrificial region in the first trench; forming a first micromechanical arm array in the silicon sacrificial region; forming a second micromechanical arm array in the silicon sacrificial region; patterning and etching a top portion of each micromechanical arm in the first micromechanical arm array to form a protrusion; forming at least one polysilicon sacrificial layer on the micromechanical arms in the second micromechanical arm array and the micromechanical arms in the second micromechanical arm array, wherein the protrusion of each micromechanical arm in the first micromechanical arm array remains exposed; forming a metal layer; and removing the silicon sacrificial region and the at least one polysilicon sacrificial layer to create a cavity.