All-SiC Acceleration-Pressure MEMS Chip for High-Temperature Isolation
Solution Overview
Problem
Existing silicon-based MEMS acceleration-pressure integrated sensor chips face limitations in high-temperature environments due to structural weaknesses that reduce measurement sensitivity and range, and they are susceptible to interference from acceleration during pressure measurement.
Innovation Solution
An all-silicon carbide (SiC) acceleration-pressure integrated sensor chip is designed with a multi-cantilever structure and arc-shaped cross beam, incorporating silicon carbide plates to enhance sensitivity and protect the sensor components, while using piezoresistive strips connected through metal ohmic contact circuits for precise measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If silicon-based materials are used for sensor preparation, then manufacturing is easier and cost is lower, but operation temperature is limited to 200°C or below
Solution Approach 1:
The patent changes the material parameter from silicon-based to silicon carbide-based, which fundamentally alters the temperature resistance property. Silicon carbide enables operation at temperatures above 200°C while maintaining sensor functionality, directly resolving the temperature limitation of conventional silicon-based sensors.
Solution Approach 2:
The patent employs composite material structure combining silicon carbide substrate with silicon dioxide insulation layers and metal ohmic contact circuits. This composite approach leverages the high-temperature resistance of silicon carbide while using well-established silicon dioxide and metal materials for manufacturing, balancing temperature performance with manufacturability.
2Volume of moving object
If a wing-shaped diaphragm structure is used in integrated sensor chip, then device size is reduced, but measurement sensitivity and range are weakened
Solution Approach 1:
The patent divides the sensing structure into separate functional modules: acceleration sensor chip with multi-cantilever structure and pressure sensor chip with diaphragm structure. This segmentation allows each module to be optimized independently - the acceleration sensor achieves compact size while the pressure sensor maintains high sensitivity through its dedicated diaphragm design, resolving the trade-off between size and sensitivity.
Solution Approach 2:
The patent transitions from planar integration to three-dimensional stacking by placing the acceleration sensor chip and pressure sensor chip in vertical layers separated by silicon carbide plates. This dimensional change enables both sensors to coexist in a compact volume while each maintains its optimal structural characteristics for high sensitivity measurement.
3Device complexity
If pressure sensor chip is integrated with acceleration sensor chip on same substrate, then integration is achieved, but acceleration interferes with pressure measurement accuracy
Solution Approach 1:
The patent extracts the acceleration sensor chip from the same substrate as the pressure sensor chip and places it in a separate layer. The silicon carbide plate acts as a physical barrier that isolates the pressure sensor chip from acceleration-induced interference, while still allowing the integrated system to function as a unified device measuring both parameters.
Solution Approach 2:
The silicon carbide plate serves as an intermediary layer between the acceleration sensor chip and pressure sensor chip. This intermediate structure provides mechanical isolation that prevents acceleration forces from directly affecting the pressure sensor measurements, while enabling electrical signal transmission and system integration.
4Measurement precision
If stress-strain amplification structure is added to sensing structure, then measurement precision for minor pressure changes is enhanced, but device complexity increases
Solution Approach 1:
The patent merges the stress-strain amplification function with the existing diaphragm structure of the pressure sensor chip. The multi-cantilever structure of the acceleration sensor serves dual purposes: measuring acceleration while also providing stress-strain amplification for pressure measurement through its beam configurations. This combining approach enhances measurement precision without proportionally increasing device complexity.
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 SiC sensor chip achieves high-sensitivity and wide-range measurement of acceleration and pressure signals in harsh environments, with improved reliability and accuracy by isolating sensors and amplifying deformation for enhanced resistance changes.
Implementation Method 1
Areas of upper surfaces of the N first support beams close to the second ends of the N first support beams are respectively provided with first piezoresistive strips; and the first piezoresistive strips are connected through a first metal ohmic contact circuit
Implementation Method 2
The emergence of the third-generation wide-bandgap semiconductor materials (e.g., silicon carbide) has promoted the application of MEMS sensors in harsh environments
Implementation Method 3
the sensing structure is often provided with a stress-strain amplification structure for amplifying the small resistance changes in varistors
Implementation Method 4
the first piezoresistive strips are connected through a first metal ohmic contact circuit
Data Source
AI summary
An all-silicon carbide micro-electro-mechanical system (MEMS) acceleration-pressure integrated sensor chip includes a first patterned silicon carbide plate, a MEMS acceleration sensor chip, a second patterned silicon carbide plate, a MEMS pressure sensor chip and a third patterned silicon carbide plate fixedly connected in sequence. The MEMS acceleration sensor chip has an eight-beam and five-mass-block structure. The MEMS pressure sensor chip includes an arc-shaped cross beam and four circular diaphragms. A method for preparing the integrated sensor chip is also provided.