Vertical MEMS Resonator Integration Over CMOS
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Solution Overview
Problem
Conventional methods for coupling MEMS resonators with CMOS circuitry face challenges such as alignment issues, gap limitations, and increased fabrication costs, limiting design possibilities and material usage.
Innovation Solution
The formation of CMOS circuitry and resonators outwardly from a semiconductor substrate, with electrodes electrically coupled to the circuitry, allowing resonators to oscillate in response to an electrostatic field, enabling close proximity and high density integration without the need for combining separate substrates or costly wire bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MEMS resonators are formed on a first substrate that is later bonded to a CMOS substrate, then electrical coupling between MEMS and CMOS is achieved, but alignment issues, MEMS-to-CMOS gap limitations, and additional fabrication costs occur
Solution Approach 1:
The patent merges the MEMS resonator formation process with the CMOS fabrication process by forming both structures outwardly from the same semiconductor substrate. This integration eliminates the need for separate substrate bonding and alignment procedures, directly resolving the technical contradiction between achieving electrical coupling and avoiding alignment issues.
2Ease of manufacture
If MEMS resonators are integrated directly with CMOS on the same wafer in a side-by-side configuration, then fabrication costs are reduced, but additional die area is required and design possibilities are limited
Solution Approach 1:
The patent transitions from a lateral side-by-side configuration to a vertical stacked configuration where the resonator is formed outwardly from the CMOS circuitry in the vertical dimension. This dimensional change allows both structures to share the same planar footprint, significantly reducing the required die area while maintaining full design flexibility.
3Ease of manufacture
If conventional MEMS-CMOS monolithic processes are used, then fabrication costs are reduced, but basic stripped-down CMOS flows limit design possibilities and material choices
Solution Approach 1:
The patent performs preliminary actions by forming the resonator structure outwardly from the CMOS circuitry during the CMOS fabrication process itself, before final device assembly. This preliminary integration allows access to full CMOS material libraries and processing capabilities, enabling advanced material choices and design possibilities while maintaining cost-effective monolithic fabrication.
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 allows for a higher density of resonators with improved signal-to-noise ratio and impedance matching, enabling complex frequency responses with high quality factors, while reducing parasitics and fabrication costs.
Implementation Method 1
an electrode is electrically coupled to the CMOS circuitry. A resonator is disposed outwardly from the electrode. The resonator is operable to oscillate at a resonance frequency in response to an electrostatic field propagated, at least in part, by the electrode.
Implementation Method 2
The resonator is operable to oscillate at a resonance frequency in response to an electrostatic field propagated, at least in part, by the electrode.
Data Source
AI summary
In accordance with one embodiment of the present disclosure, a semiconductor substrate includes complementary metal-oxide-semiconductor (CMOS) circuitry disposed outwardly from the semiconductor substrate. An electrode is disposed outwardly from the CMOS circuitry. The electrode is electrically coupled to the CMOS circuitry. A resonator is disposed outwardly from the electrode. The resonator is operable to oscillate at a resonance frequency in response to an electrostatic field propagated, at least in part, by the electrode.