MEMS Acceleration Sensor Electrode Interval Control
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Solution Overview
Problem
Existing MEMS acceleration sensors face limitations in narrowing the interval between movable and fixed electrodes due to etching aspect ratio constraints, which affects sensitivity and is prone to manufacturing errors and temperature changes.
Innovation Solution
The acceleration sensor employs an electrostatic force to deform a beam portion, narrowing the interval between movable and fixed electrodes, and a regulating portion maintains a predetermined interval, improving sensitivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etching is used to form electrodes, then manufacturing is feasible, but the interval between electrodes cannot be narrowed beyond etching aspect ratio limits
Solution Approach 1:
A beam portion is introduced as an intermediary mechanical element between the substrate and the fixed electrode. This beam portion can be elastically deformed to adjust the electrode interval, thereby decoupling the electrode spacing from the constraints of the etching process and enabling narrower intervals without increasing etching aspect ratio
Solution Approach 2:
The physical state of the beam portion is changed from rigid to elastically deformable. By applying external force or utilizing material elasticity, the beam portion's deflection is controlled to achieve desired electrode spacing, transforming the fixed geometric constraint into a可调 mechanical parameter
2Measurement precision
If electrode interval is narrowed to improve sensitivity, then sensitivity increases, but manufacturing errors and temperature changes affect stability
Solution Approach 1:
The beam portion is designed as a dynamic, elastically deformable element rather than a rigid structure. This allows the system to adapt to manufacturing variations and temperature changes through elastic deformation, maintaining stable electrode spacing and thus reliable sensitivity performance under varying conditions
Solution Approach 2:
The elastic beam portion serves as a pre-designed compensation mechanism that anticipates and cushions against the effects of manufacturing errors and temperature variations. By incorporating this elastic element beforehand, the system preemptively mitigates potential instability without requiring active control
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 allows for enhanced sensitivity and stability by narrowing the electrode interval beyond etching limitations and maintaining it despite manufacturing errors or temperature changes.
Implementation Method 1
an electrode portion configured to, when a voltage is applied to the electrode portion, deform the beam portion by an electrostatic force, and make an interval in the second direction between the movable electrode finger and the fixed electrode finger narrower than the interval before the deformation of the beam portion
Data Source
AI summary
Provided is a MEMS device including a substrate that has a first principal surface and a second principal surface facing the first principal surface, and in which a cavity recessed from the first principal surface side to the second principal surface side is disposed, and a MEMS electrode that is disposed within the cavity, and that is separated from a bottom surface of the cavity to the first principal surface side. The MEMS includes a movable electrode finger, a fixed electrode finger, a beam portion, and an electrode portion. The electrode portion includes a first electrode finger and a second electrode finger.