Semiconductor Pressure Sensor with Integrated Cavity and Movable Electrode
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Solution Overview
Problem
Conventional pressure sensors face challenges in size reduction and manufacturing complexity, with increased capacitance requirements for precise pressure detection, which complicates the reduction of the movable electrode area and increases manufacturing costs.
Innovation Solution
A pressure sensor design featuring a semiconductor substrate with a recess and a semiconductor layer separated by an insulating layer, where the semiconductor layer overlaps a cavity portion, allowing for a movable portion that can be easily formed and sealed, reducing the need for multiple substrates and simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two semiconductor substrates are bonded together to form a pressure sensor, then the pressure sensor can be manufactured with a cavity portion and insulating layer, but the manufacturing process becomes complicated and manufacturing cost increases
Solution Approach 1:
The patent merges the functions of multiple substrates into a single semiconductor substrate. The first substrate serves as both the base substrate and the support for the movable electrode, eliminating the need for a separate second substrate. This integration simplifies the manufacturing process by reducing the number of bonding steps and processing operations required for each substrate.
Solution Approach 2:
The single semiconductor substrate performs multiple functions: it serves as the base substrate, provides structural support, forms part of the capacitor structure, and supports the movable electrode. This multi-functionality reduces the overall device complexity and manufacturing cost while maintaining the necessary pressure sensor functionality.
2Measurement precision
If the facing area of fixed electrode and movable electrode is increased to detect capacitance changes more precisely, then measurement precision improves, but the area of movable electrode cannot be reduced which hinders size reduction
Solution Approach 1:
The patent extends the capacitor structure into the vertical dimension by forming the movable electrode as a protruding structure that extends from the surface of the base substrate. This three-dimensional configuration increases the effective facing area between the fixed and movable electrodes without increasing the planar footprint, enabling precise capacitance detection while maintaining a compact device size.
Solution Approach 2:
The movable electrode is formed as a protruding structure that extends from the base substrate, effectively nesting the capacitor structure within the device volume. This nested configuration maximizes the capacitance detection area within a compact form factor, allowing precise pressure measurement without increasing the overall device size.
3Reliability
If processing to form wiring and electrode is performed with respect to each substrate, then proper electrical connections are achieved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent combines the electrode formation processes for both substrates into a single processing sequence on one substrate. The movable electrode is formed directly on the base substrate, and the fixed electrode is formed on the opposing surface, eliminating the need for separate wiring processing on two distinct substrates. This reduces manufacturing complexity while ensuring proper electrical connections.
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 design enables more precise pressure measurement with a larger capacitance between the semiconductor substrate and layer, facilitating size reduction while lowering manufacturing costs by using a single semiconductor substrate and simplifying the manufacturing process.
Implementation Method 1
an insulating layer (20) and a semiconductor layer (30) which are formed on the semiconductor substrate (10)
Implementation Method 2
The pressure sensor (1) detects changes in pressure by detecting changes in capacitance between the semiconductor substrate (10) and the semiconductor layer (30)
Data Source
AI summary
A pressure sensor 1 comprises a semiconductor substrate 10, insulating layers 21, 22, 23 formed on the semiconductor substrate 10, a semiconductor layer 30 formed on the semiconductor substrate 10 with the insulating layers 21, 23 intervening therebetween, and a cavity portion 13 provided between the semiconductor substrate 10 and the semiconductor layer 30. The portion of the semiconductor layer 30 which overlaps the cavity portion 13 as viewed in a lamination direction serves as a movable portion 31. The cavity portion 13 is surrounded by the insulating layers 22, 23. With this arrangement, the pressure sensor 1 can be manufactured easily with high precision.