Capacitance Pressure Sensor Single Substrate Integration
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Solution Overview
Problem
The manufacturing of capacitance type pressure sensors using MEMS technology is costly and bulky due to the need for bonding two substrates, which increases the number of manufacturing steps and volume, and results in higher costs and larger size.
Innovation Solution
A capacitance type pressure sensor is designed using a single semiconductor substrate with a diaphragm and a reference pressure compartment, where the diaphragm is formed from the substrate and isolated by an insulating layer, allowing for hermetic sealing and reduced size, and integrated circuit devices can be formed on the same substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two substrates are bonded together to form a pressure sensor, then the pressure sensor can be manufactured with a diaphragm and reference pressure compartment, but the manufacturing cost increases and the device size becomes larger
Solution Approach 1:
The patent merges the diaphragm and reference pressure compartment into a single semiconductor substrate. The diaphragm is formed by thinning a first region of the substrate, while a second region maintains its original thickness to form the reference pressure compartment. This eliminates the need to bond two separate substrates, reducing manufacturing complexity and cost while maintaining the required pressure sensing functionality.
Solution Approach 2:
The single semiconductor substrate is segmented into different functional regions: a first region that is thinned to form the diaphragm, and a second region that maintains original thickness to form the reference pressure compartment. This segmentation allows both the diaphragm and reference chamber to coexist in one substrate without requiring separate substrate bonding.
2Reliability
If two substrates are used to manufacture a pressure sensor, then the diaphragm and reference pressure compartment can be formed, but the volume of the pressure sensor increases
Solution Approach 1:
By combining the diaphragm and reference pressure compartment into a single semiconductor substrate, the overall volume of the pressure sensor is reduced. The integrated structure eliminates the need for bonding interfaces and reduces the total material volume required, while still providing the necessary functional separation between the diaphragm region and reference pressure compartment.
3Reliability
If two substrates are bonded together, then the pressure sensor can detect pressure, but the number of manufacturing steps increases
Solution Approach 1:
The patent integrates both the diaphragm and reference pressure compartment formation into a single substrate processing sequence. This eliminates the substrate bonding step and associated alignment and sealing operations, significantly reducing the number of manufacturing steps while maintaining pressure detection capability through the thinned first region.
4Measurement precision
If two substrates are used, then electrodes can be formed in both substrates for capacitance measurement, but the manufacturing cost increases
Solution Approach 1:
The patent maintains the capacitance measurement functionality by forming electrodes in the thinned first region (diaphragm area) and the opposing second region (reference pressure compartment area) within the same substrate. This integrated approach preserves the differential capacitance measurement capability while eliminating the cost associated with processing and bonding two separate substrates.
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 configuration reduces manufacturing costs and size, enhances sensitivity by improving the diaphragm's response to pressure changes, and allows for a simpler and more accurate capacitance-based pressure detection method.
Implementation Method 1
the capacitance type pressure sensor detects a pressure acting on the diaphragm based on a change in capacitance between the diaphragm and the bottom surface of the reference pressure compartment
Data Source
AI summary
A capacitance type pressure sensor includes a semiconductor substrate having a reference pressure compartment formed therein, a diaphragm formed of a portion of the semiconductor substrate and formed in a surface layer portion of the semiconductor substrate to define the reference pressure compartment, the diaphragm having a through-hole communicating with the reference pressure compartment, fillers arranged within the through-hole, and an isolation insulating layer surrounding the diaphragm to isolate the diaphragm from the remaining portion of the semiconductor substrate.