Surface Elastic Wave Generator Depletion Capacitance CMOS Integration
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Solution Overview
Problem
MEMS resonators face challenges with high impedance, complex structure requirements, and difficulties in integration with CMOS processing due to large feed-through capacitor signals and complex structure release etching processes, limiting their application in higher frequency devices.
Innovation Solution
A surface elastic wave generator using a depletion capacitance region is developed, which includes a substrate with a first conductivity type region and a second conductivity type doped region. By applying reverse bias to the junctions between these regions, a depletion capacitance region is formed, allowing for the generation of electrostatic force and surface elastic waves through signal input, thereby reducing impedance and simplifying fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If MEMS resonators are used to achieve frequency reference functions, then acceptable accuracy is obtained, but high impedance causes limitations in higher frequency applications and difficulties in processing back-end circuits
Solution Approach 1:
The patent replaces the mechanical MEMS resonator structure with an electronic surface elastic wave generator that uses semiconductor doping regions and electrical fields to generate and detect elastic waves, thereby eliminating the high impedance problem while maintaining frequency reference functionality
Solution Approach 2:
The patent changes the fundamental operating parameters from MEMS mechanical resonance to surface elastic wave propagation in semiconductor materials, enabling higher frequency operation and better circuit integration while maintaining acceptable frequency accuracy
2Measurement precision
If capacitive resonators are used, then frequency reference function is achieved, but large feed through capacitor signals result in higher feed through
Solution Approach 1:
The patent replaces the capacitive resonator structure with a surface elastic wave-based generator that uses mechanical wave propagation rather than electrical capacitance, thereby eliminating large feed through signals while maintaining frequency reference functionality
3Measurement precision
If MEMS resonators are fabricated, then frequency reference devices are produced, but complex structure release etching process makes them difficult to fabricate and integrate with CMOS processing
Solution Approach 1:
The patent replaces the mechanical MEMS structure requiring release etching with a solid-state surface elastic wave generator that can be fabricated using standard semiconductor doping and metallization processes compatible with CMOS technology
Solution Approach 2:
The patent changes the fabrication approach from mechanical MEMS release etching to semiconductor-based doping and metallization processes, enabling straightforward CMOS integration while maintaining frequency reference device performance
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 solution effectively reduces impedance, inhibits feed-through, and simplifies the fabrication process, enabling the integration of surface elastic wave generators with CMOS processing and improving their performance in higher frequency applications.
Implementation Method 1
Through applying reverse bias to junctions between the first conductivity type region and the second conductivity type doped region, a depletion capacitance region is formed, and through inputting a signal to the first conductivity type region or the second conductivity type doped region, an elastic wave is generated on the substrate
Implementation Method 2
a surface elastic wave is generated on the substrate
Data Source
AI summary
A surface elastic wave generator may include a substrate. A first conductivity type region is formed in the substrate. A second conductivity type doped region includes at least one doping pattern doped on surface of the first conductivity type region. Through applying reverse bias to junctions between the first conductivity type region and the second conductivity type doped region, a depletion capacitance region is formed. Also, through inputting signal to the first conductivity type region or the second conductivity type doped region, the surface elastic wave is generated on the substrate. In addition, a surface elastic wave transceiver and surface elastic wave generation method are also provided.