MEMS Resonator Anchor Structure Using Nodal Support Points
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Solution Overview
Problem
Conventional MEMS resonators experience significant anchor losses due to vibrational energy dissipation through anchors into the substrate, limiting their quality factor (Q), and face fabrication challenges with long support beams that can lead to resonator body bending and degradation.
Innovation Solution
The design incorporates mechanically symmetric support structures with coupling beams of variable lengths, where anchor points are selected as nodal points with minimal vibration, reducing energy loss and improving the quality factor (Q) by minimizing anchor losses and allowing for shorter, more manageable beam lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If quarter-wavelength support beams are used in conventional MEMS resonators, then the resonator can be designed with a specific resonant frequency, but significant vibrational energy is dissipated through the anchors into the substrate, reducing the quality factor
Solution Approach 1:
The patent extracts the harmful anchor points from the support beam structure by using cantilever beams that are fixed at one end and free at the other. This eliminates the need for anchors that dissipate vibrational energy into the substrate, thereby reducing energy loss and improving quality factor
Solution Approach 2:
Instead of fixing both ends of the support beam with anchors (conventional approach), the patent inverts the approach by fixing only one end and leaving the other end free. This inversion of the boundary conditions eliminates anchor-related energy dissipation while maintaining the resonant frequency characteristics
2Length of moving object
If quarter-wavelength support beams are used to achieve desired resonant frequency, then the frequency can be controlled, but the support beams become relatively long causing fabrication issues and resonator body bending
Solution Approach 1:
The patent changes the boundary condition parameters of the support beam from fixed-fixed (with anchors) to fixed-free (cantilever). This parameter change allows for shorter beam lengths while maintaining the desired resonant frequency, thereby improving fabrication precision and eliminating bending issues
3Strength
If anchors are used to provide counter action at anchor points, then the anchor points can be kept fixed, but manufacturing issues cause anchors to float and vibrate, dissipating energy into the substrate
Solution Approach 1:
The patent removes the anchors entirely from the design by using cantilever beams with a fixed-free boundary condition. This extraction of the anchor component eliminates the problem of anchor floating and vibration, while the fixed end of the cantilever beam provides the necessary structural support without energy dissipation
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 significantly enhances the quality factor (Q) of MEMS resonators by reducing anchor losses and mitigating fabrication issues, enabling improved frequency selectivity and stability.
Implementation Method 1
anchor points are selected as nodal points on the mechanically symmetric support component at which there is essentially no vibration
Data Source
AI summary
Micro-Electro-Mechanical Systems (MEMS) resonator designs having support structures that minimize or substantially reduce anchor losses, thereby improving a quality factor (Q) of the MEMS resonators, are provided. In general, a MEMS resonator includes a resonator body connected to anchors via support structures. The anchors are connected to or are part of a substrate on which the MEMS resonator is formed. The support structures operate to support the resonator body in free space to enable vibration. The support structures are designed to minimize or substantially reduce energy loss through the anchors into the substrate.