Single-Substrate Piezoresistive Pressure Sensor Integration
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Solution Overview
Problem
Conventional piezoresistive pressure sensors require two separate substrates and struggle to integrate sensors and circuits into a single substrate, limiting their miniaturization and manufacturing efficiency.
Innovation Solution
A micro piezoresistive pressure sensor is developed using a single silicon substrate with a buried cavity and a laminated membrane structure, integrated with CMOS devices, formed through a CMOS device manufacturing process, including trench etching, thermal oxidation, and diffusing thermal treatment processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional piezoresistive pressure sensor is manufactured using bulk micromachining and hetero-substrate attaching, then the sensor can be manufactured with a membrane and closed cavity, but the device requires two separate substrates and cannot easily integrate sensors and circuits into a single substrate
Solution Approach 1:
The patent merges the pressure sensing structure and semiconductor circuit into a single silicon substrate. The method uses CMOS-compatible processes to fabricate both the piezoresistive pressure sensor and integrated circuits on the same substrate, eliminating the need for separate substrate attachment and reducing device complexity.
Solution Approach 2:
The silicon substrate serves multiple functions: it acts as the base for the piezoresistive pressure sensor, contains the semiconductor circuit, and provides structural support. This multi-functional approach allows both sensing and signal processing to be integrated in one chip.
2Productivity
If two hetero substrates are used for manufacturing conventional piezoresistive pressure sensors, then the membrane and closed cavity can be formed, but the manufacturing process becomes complicated and production cost increases
Solution Approach 1:
The patent combines the manufacturing of the pressure sensing structure and semiconductor circuit into a single CMOS-compatible fabrication process on one substrate, eliminating the need for separate substrate processing and attachment steps, thereby simplifying the manufacturing process and improving productivity.
Solution Approach 2:
The patent changes the material parameter from hetero-substrate combination to homogeneous silicon substrate, and changes the manufacturing process parameters to be CMOS-compatible, which enables standard semiconductor fabrication techniques to be used for both the sensor and circuit, significantly improving ease of manufacture.
3Volume of moving object
If a single substrate is used to integrate pressure sensing structure and semiconductor circuit, then device size is reduced and manufacturing is simplified, but the membrane structure and cavity formation must be achieved within the same substrate
Solution Approach 1:
The patent segments the silicon substrate into different functional regions: one region for the pressure sensing structure with cavity and membrane, and another region for the semiconductor circuit. This segmentation allows each region to be optimized for its specific function while maintaining integration on a single substrate.
Solution Approach 2:
The patent applies local quality by creating a cavity and membrane structure in a specific region of the silicon substrate while maintaining the bulk substrate integrity for circuit fabrication. The cavity formation and membrane structure are localized to the sensing region, allowing precise control over the sensing element while preserving the substrate's suitability for CMOS circuit manufacturing.
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 approach allows for the integration of pressure sensing structures and semiconductor circuits in a single chip, simplifying manufacturing, reducing production costs, and enabling mass production compatibility with existing CMOS processes.
Implementation Method 1
a piezoresisive pressure sensor, capable of implementing a pressure sensing structure having a closed cavity and a membrane and a semiconductor integrated circuit in a single substrate
Implementation Method 2
forming a cavity buried in the silicon substrate; a membrane which has a laminated structure formed on an upper portion of the silicon substrate to close the cavity
Implementation Method 3
sensitive films which are constructed with a piezoresisive material formed on an upper portion of the membrane
Data Source
AI summary
A micro semiconductor-type pressure sensor and a manufacturing method thereof are provided. The micro semi-conductor-type pressure sensor is implemented by etching a cavity-formation region of a substrate to form a plurality of trenches, oxidizing the plurality of trenches through a thermal oxidation process to form a cavity-formation oxide layer, forming a membrane-formation material layer on upper portions of the cavity-formation oxide layer and the substrate, forming a plurality of etching holes in the membrane-formation material layer, removing the cavity-formation oxide layer through the plurality of etching holes to form a cavity buried in the substrate, forming a membrane reinforcing layer on an upper portion of the membrane-formation material layer to form a membrane for closing the cavity, and forming sensitive films made of a piezoresisive material on an upper portion of the membrane.