Resonator with CMOS on Lid and Through-Electrode
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Solution Overview
Problem
Existing piezoelectric resonance devices with MEMS technology face challenges in maintaining a vacuum state within the vibration space without increasing the product height, as the CMOS device is not designed to prevent outgassing, which affects the resonance characteristics.
Innovation Solution
A resonance device configuration that includes a resonator with a lower and upper electrode and a piezoelectric film, sealed by MEMS lids, with a CMOS device mounted on the lids, featuring through-electrodes for electrical connection and a protective layer to prevent outgassing, maintaining a vacuum state without increasing the device height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the CMOS device is mounted on the resonator package to reduce product height, then the height is reduced, but outgassing occurs from the CMOS device materials which decreases the vacuum degree in the vibration space
Solution Approach 1:
The patent extracts the harmful function (outgassing) from the CMOS device by removing the organic protective layer that causes outgassing, while retaining the essential function (electrical connection and oscillation control). This allows the CMOS device to be mounted on the package for height reduction without compromising vacuum maintenance.
Solution Approach 2:
The patent converts the harmful outgassing effect into a beneficial situation by selectively removing only the organic protective layer that causes outgassing, while preserving the functional layers of the CMOS device. The CMOS device can then be mounted on the package (reducing height) without the harmful outgassing effect.
2Reliability
If the organic protective layer is removed from the CMOS device to prevent outgassing, then vacuum maintenance is improved, but the CMOS device becomes exposed and susceptible to environmental damage
Solution Approach 1:
The patent applies local quality by providing different protective treatments to different parts of the CMOS device. The organic protective layer is removed only from the surface that faces the vibration space (where outgassing would occur), while other surfaces retain their protective layers for environmental protection.
Solution Approach 2:
The protective layer is segmented into functional regions: the organic protective layer is removed from the vibration space-facing surface to prevent outgassing, while inorganic protective layers are retained on other surfaces for environmental protection. This segmentation allows simultaneous achievement of vacuum maintenance and environmental protection.
3Length of moving object
If the CMOS device is integrated inside the package, then height is reduced, but the circuit is exposed to the vibration space causing outgassing
Solution Approach 1:
The patent extracts the harmful organic protective layer from the CMOS device while retaining the device itself mounted on the package. This extraction eliminates the outgassing source while maintaining the height-reduction benefit of integrating the CMOS device with the resonator package.
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 maintains a high vacuum in the vibration space while keeping the product height unchanged, ensuring stable resonance characteristics by preventing outgassing and integrating the CMOS device outside the package.
Implementation Method 1
a resonator that includes a lower electrode, an upper electrode, and a piezoelectric film that is formed between the lower electrode and the upper electrode
Implementation Method 2
a vibration space in which a resonator vibrates needs to be sealed in an airtight state by using a package and a vacuum state needs to be maintained to stabilize resonance characteristics
Data Source
AI summary
A resonator including a lower electrode, an upper electrode, and a piezoelectric film that is formed between the lower electrode and the upper electrode. A MEMS device is provided that includes an upper lid that faces the upper electrode, and a lower lid that faces the lower electrode and that seals the resonator together with the upper lid. A CMOS device is mounted on a surface of the upper lid or the lower lid opposite a surface that faces the resonator. The CMOS device includes a CMOS layer and a protective layer that is disposed on a surface of the CMOS layer opposite a surface that faces the resonator. The upper or lower lid to which the CMOS device is joined includes a through-electrode that electrically connects the CMOS device to the resonator.