MEMS Pressure Sensor with Stacked Cavities for Multi-Range Detection
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Solution Overview
Problem
Existing MEMS pressure sensors face challenges with large membrane areas and reduced sensitivity across different pressure ranges, making them unsuitable for integration in small devices and reducing reliability.
Innovation Solution
A MEMS pressure sensor design featuring a monolithic body with multiple buried cavities and sensitive regions, each with piezoresistive sensing elements, allowing for deflection and sensitivity adjustment based on pressure amplitude, enabling operation across various pressure ranges without performance loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If single-membrane or side-by-side membrane structures are used to detect different pressure ranges, then the sensor can operate in multiple pressure ranges, but the area occupied by the membrane becomes large
Solution Approach 1:
The patent transitions from a planar side-by-side membrane arrangement to a vertical stacked configuration with multiple buried cavities at different depths. This dimensional change allows multiple sensing regions to occupy the same lateral footprint while operating at different pressure ranges, effectively resolving the area constraint.
Solution Approach 2:
The patent implements nested buried cavities where a first buried cavity and a second buried cavity are positioned at different depths within the semiconductor body. The second cavity extends laterally beyond the first cavity, creating a nested configuration that enables multi-range pressure detection within a compact vertical structure.
2Area of stationary object
If single-membrane structures are used to reduce area, then the device size is reduced, but the sensitivity performance deteriorates in certain pressure ranges
Solution Approach 1:
The patent divides the sensing structure into multiple segmented regions: a first sensitive region with a first piezoresistive sensing element for detecting lower pressure ranges, and a second sensitive region with a second piezoresistive sensing element for detecting higher pressure ranges. Each segment is optimized for its specific pressure range, maintaining high sensitivity across the full operating spectrum.
Solution Approach 2:
The patent applies local quality by creating distinct sensing zones with different characteristics. The first buried cavity and first sensitive region are optimized for one pressure range, while the second buried cavity and second sensitive region are optimized for another pressure range. Each region has tailored piezoresistive elements positioned to maximize sensitivity for its designated pressure range.
3Adaptability or versatility
If side-by-side membrane structures are designed for different pressure ranges, then multi-range operation is achieved, but the manufacturing complexity increases
Solution Approach 1:
The patent merges multiple sensing functions into a single integrated semiconductor body structure. Instead of separate side-by-side membranes requiring independent fabrication, the patent combines first and second buried cavities, first and second sensitive regions, and first and second piezoresistive sensing elements into one monolithic device, simplifying manufacturing while achieving multi-range detection.
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 design achieves compact size and maintains sensitivity across different pressure ranges, enhancing reliability and efficiency in small devices.
Implementation Method 1
this deformation causes a variation of the electrical resistivity of the material forming the piezoresistive elements, thus generating an electrical signal
Data Source
AI summary
A MEMS pressure sensor includes a monolithic body of semiconductor material having a first face and a second face and housing a first buried cavity and a second buried cavity, arranged under the first buried cavity and projecting laterally therefrom. A first sensitive region is formed between the first buried cavity and the first face at a first depth, and a second sensitive region is formed between the second buried cavity and the first face at a second depth greater than the first depth. The monolithic body also houses a first piezoresistive sensing element and a second piezoresistive sensing element, integrated in the first and second sensitive regions, respectively.