3D Capacitive Pressure Sensor Vertical Electrode Design
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Solution Overview
Problem
Conventional capacitive pressure sensors have low sensitivity and occupy a large area on semiconductor substrates, limiting their integration level and performance.
Innovation Solution
A method for fabricating three-dimensional capacitive pressure sensors using MEMS technology, involving the formation of trenches, electrodes, sacrificial layers, and sealing layers to increase the overlap area and sensitivity while minimizing substrate occupancy, including specific processes like dry etching, sputtering, and chemical mechanical polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional planar capacitor structure is used, then fabrication process is simple, but sensitivity is low and substrate area occupancy is large
Solution Approach 1:
The patent transitions from a planar two-dimensional capacitor structure to a three-dimensional structure by forming electrodes that extend vertically into the substrate. The first electrode is formed on the substrate surface, and the second electrode is formed within the substrate at a different depth, creating a vertical stacking arrangement that increases sensitivity while reducing the horizontal footprint on the substrate.
2Measurement precision
If three-dimensional electrode structure is formed, then sensitivity and integration level increase, but fabrication process complexity increases
Solution Approach 1:
The fabrication process is segmented into distinct stages: first forming the initial electrode structure, then creating sacrificial layers to define chamber regions, selectively removing sacrificial layers to form chambers, and finally forming the second electrode. This segmentation allows complex three-dimensional structures to be built through a series of simpler, standardized MEMS fabrication steps.
Solution Approach 2:
Sacrificial layers are introduced as intermediary materials during fabrication. These sacrificial layers are temporarily deposited to define the chamber spaces, then selectively removed to create the desired three-dimensional electrode configuration. The sacrificial layers act as placeholders that enable precise chamber formation without requiring direct complex patterning of the final electrode structure.
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 approach enhances the sensitivity and integration level of capacitive pressure sensors by increasing the overlap area between electrodes, allowing for more precise pressure detection without significantly increasing the device's footprint on the substrate.
Implementation Method 1
the capacitance of the planar capacitor can be calculated by an equation (1): C=∈S/d... The capacitance change of the planar capacitor can be detected by the control circuit, and the pressure change is obtained
Implementation Method 2
When a pressure is applied on the membrane 13 of the planar capacitor, or the inside of the membrane 13 and the outside of the membrane 13 has a pressure difference, the center of the membrane 13 is deformed
Data Source
AI summary
A capacitive pressure sensor is provided. The capacitive pressure sensor includes a substrate; and a first electrode formed in one surface of the substrate and vertical to the surface of the substrate. The capacitive pressure sensor also includes a second electrode with a portion facing the first sub-electrode, a portion facing the second sub-electrode and a portion formed in the other surface of the substrate. Further, the capacitive pressure sensor includes a first chamber between the first electrode and the second electrode and a second chamber formed in the second electrode. Further, the pressure sensor also includes a first sealing layer formed on the second electrode; and a second sealing layer formed on the other surface of the substrate.