Pressure-Sensitive Transistor Membrane Structure
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Solution Overview
Problem
Current manufacturing processes for capacitive pressure sensors face limitations in miniaturization due to sensitivity dependence on the active area of the capacitor, making it challenging to produce sensors with reduced area requirements while maintaining sensitivity to pressure changes.
Innovation Solution
A method for manufacturing a pressure sensitive transistor involves forming a semiconductor substrate with a channel region, a sacrificial structure, and a membrane structure that is displaceable in response to pressure changes, allowing for the integration of a pressure-sensitive field effect transistor that can detect changes in capacitance and channel resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If capacitive pressure sensors are miniaturized, then area requirements are reduced, but sensitivity to pressure changes deteriorates
Solution Approach 1:
The patent changes the operational parameter from capacitive sensing to field effect transistor sensing. By using a PFET where the membrane structure modulates channel conductivity through pressure-induced displacement, the sensor achieves high sensitivity with reduced area requirements compared to traditional capacitive sensors.
Solution Approach 2:
The patent replaces the capacitive measurement system with a field effect transistor-based electrical measurement system. The membrane displacement is transduced into channel conductivity changes rather than capacitance changes, enabling miniaturization while maintaining sensitivity.
2Area of moving object
If sensor area is reduced, then miniaturization is achieved, but manufacturing complexity increases
Solution Approach 1:
The membrane structure serves multiple functions: it acts as both the pressure-sensing element and the gate electrode of the PFET. This multi-functionality reduces the number of separate components and simplifies the manufacturing process despite the reduced sensor area.
Solution Approach 2:
The patent merges the membrane structure with the control electrode function in a single integrated component. The semiconductor layer is formed directly on the sacrificial structure, creating an integrated PFET where the membrane and gate are unified, reducing manufacturing steps.
3Area of stationary object
If capacitive sensor active area is reduced, then miniaturization is achieved, but sensitivity deteriorates
Solution Approach 1:
The patent replaces capacitive sensing with field effect transistor sensing. The PFET measures pressure through changes in channel conductivity caused by membrane displacement, providing higher sensitivity with smaller active area compared to capacitive sensing.
Solution Approach 2:
The patent changes the sensing mechanism from measuring capacitance changes to measuring channel conductivity changes. This parameter change enables the sensor to achieve high sensitivity with reduced active area by utilizing the field effect transistor's transconductance characteristics.
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 enables the production of pressure-sensitive transistors with enhanced sensitivity and reduced area requirements, allowing for further scaling and increased reliability, which is not achievable with traditional capacitive pressure sensors.
Implementation Method 1
the membrane structure 30 forms a control electrode of the pressure sensitive transistor 10 and has a center region 30-1 which is displaceable in response to a changed pressure difference ΔP
Implementation Method 2
pressure sensitive field effect transistor 10 comprising a semiconductor substrate 12 having a channel region 22 between a first contact region 18 and a second contact region 20
Data Source
AI summary
A method for manufacturing a pressure sensitive transistor includes forming a channel region between first and second contact regions in a semiconductor substrate, forming a first isolation layer on a surface of the semiconductor substrate, forming a sacrificial structure on the first isolation layer and above the channel region, forming a semiconductor layer on the sacrificial structure and on the first isolation layer, wherein the semiconductor layer covers the sacrificial structure, removing the sacrificial structure for providing a cavity between the substrate and the semiconductor layer, wherein the semiconductor layer forms a membrane structure and forms a control electrode of the pressure sensitive transistor, forming a second isolation layer on the membrane structure and on the exposed portion of the surface of the semiconductor substrate, and forming contacting structures for the first contact region, the second contact region and the membrane structure of the pressure sensitive transistor.