MEMS Resonator Beam-Frame Structure for Compact Hermetic Packaging
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Solution Overview
Problem
Conventional micromechanical resonators face challenges in achieving smaller sizes due to the physical dimensions of quartz crystal resonators, which limit their ability to vibrate efficiently at desired frequencies, and existing designs result in larger package sizes due to the need for hermetic enclosure and electrical connections.
Innovation Solution
A microelectromechanical system (MEMS) resonator structure with a vibration portion having multiple beams, anchors, and support beams that stabilize and connect the vibration portion within a frame, allowing for a smaller package size by optimizing the arrangement of masses and electrical contacts to reduce the overall length and width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resonator is hermetically enclosed inside a package with frame and via contacts, then the reliability and electrical connectivity are improved, but the total package size increases significantly
Solution Approach 1:
The patent merges the frame structure with the vibrating beams by making the beams extend directly to the frame boundaries, eliminating the need for separate support structures. The via contacts are integrated into the frame corners, combining electrical connection functions with the structural frame, thereby reducing overall package size while maintaining hermetic enclosure and electrical connectivity
Solution Approach 2:
The frame serves multiple functions simultaneously: it provides hermetic enclosure, structural support, electrical connection pathways, and mounting surfaces for via contacts. The vibrating beams serve both as structural elements and as electrical connection carriers, reducing the need for separate components and minimizing package dimensions
2Ease of operation
If via contacts are provided outside the resonator for electrical connections, then the electrical connectivity is improved, but the area required for connections increases
Solution Approach 1:
The via contacts are merged with the frame structure, positioned at the frame corners rather than being separate external components. This integration allows electrical connections to be made through the frame itself, reducing the area required for external connections while maintaining full electrical connectivity to the vibrating beams
Solution Approach 2:
The via contacts are positioned at the corners of the frame, utilizing the peripheral dimension rather than requiring additional external connection area. This spatial arrangement allows electrical connections to be made at the boundaries of the package, minimizing the overall footprint while maintaining connectivity
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
The MEMS resonator design achieves a smaller total package size, reducing the length by over 20% compared to conventional designs, while maintaining efficient vibration and electrical connectivity, making it suitable for applications like clock resonators and gyroscope structures.
Implementation Method 1
The beams for such a device will typically have a length of 400-650 μm for the length, a width of 40-60 μm, and a height of 4-6 μm. Moreover, the piezoelectric transducer is typically made of AlN (aluminum nitride) with a metal (e.g. molybdenum) electrodes.
Implementation Method 2
at least one anchor disposed between a pair of the at least three vibrating beams and configured to stabilize the vibration portion within the frame
Implementation Method 3
at least one support beam coupling the base of the vibration portion to the at least one anchor
Data Source
AI summary
A micromechanical resonator is provided that enables a smaller total package size with an acceptable quality factor for timing applications. The MEMS resonator includes a vibration portion with a base and three or more vibrating beams extending therefrom. Moreover, the MEMS resonator includes a frame that surrounds a periphery of the vibration portion and a pair of anchor between the vibrating beams for stabilizing the vibration portion within the frame. Furthermore, support beams couple the base of the vibration portion to the pair of anchors.