MEMS Movable Portion Isolation Joint Geometry
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Solution Overview
Problem
Conventional MEMS devices face issues with insulation joint damage due to deformation of the movable portion, leading to reduced insulation effectiveness.
Innovation Solution
The MEMS device incorporates an isolation joint with a specific geometry where the movable portion is designed to contact the cavity bottom before the isolation joint, ensuring a sufficient space is maintained to prevent contact and damage, utilizing a manufacturing method involving multiple etching steps and chemical vapor deposition to form a hollow beam structure with an insulative trench.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the movable portion is made hollow to reduce weight, then weight is reduced, but the isolation joint becomes vulnerable to damage during deformation
Solution Approach 1:
The patent applies preliminary action by pre-forming the isolation joint with a protruding lower end before the movable portion undergoes deformation. This preliminary structural configuration ensures that during subsequent deformation, the isolation joint maintains its insulation function by being positioned to contact the cavity bottom first, preventing damage before it occurs.
Solution Approach 2:
The patent utilizes dimensionality change by extending the isolation joint in the vertical dimension with a protruding lower end that extends beyond the movable portion's lower end. This vertical extension creates a protective geometric relationship where the isolation joint contacts the cavity bottom before the movable portion, adding a dimensional advantage to prevent damage during deformation.
2Reliability
If the isolation joint is extended downward to ensure insulation, then insulation effectiveness is improved, but the joint becomes more susceptible to contact damage with cavity bottom
Solution Approach 1:
The patent introduces an intermediary geometric relationship where the protruding lower end of the isolation joint acts as a mediator between the movable portion and the cavity bottom. This intermediary structure ensures that the isolation joint contacts the cavity bottom first during deformation, protecting the insulation function while managing the damage risk through controlled contact geometry.
3Manufacturing precision
If multiple etching steps are used to form the hollow beam structure, then manufacturing precision is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the manufacturing process into multiple discrete etching steps: first etching the isolation joint, then etching the movable portion, and finally forming the hollow cavity. This segmentation allows each step to be optimized independently, achieving high precision for the beam structure while managing overall process complexity through systematic breakdown of the manufacturing sequence.
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 configuration effectively prevents isolation joint damage and maintains reliable insulation, enhancing the structural integrity and operational reliability of the MEMS device.
Implementation Method 1
utilizing a manufacturing method involving multiple etching steps and chemical vapor deposition to form a hollow beam structure with an insulative trench
Data Source
AI summary
The present disclosure provides a MEMS device. The MEMS device includes: a substrate; a recess, disposed in the substrate; a movable portion, hollowly supported in the recess; and an isolation joint, inserted into a predetermined position of the movable portion and electrically insulating both sides of the movable portion. A shortest distance between a bottom of the recess and the movable portion is less than a distance between the bottom of the recess and the isolation joint.