Semiconductor Pressure Sensor Stress Buffering via Segmentation
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Solution Overview
Problem
Semiconductor pressure sensors are prone to offset, linearity, and hysteresis errors due to mechanical stress and deformation of the housing, which are exacerbated by temperature and humidity changes, and cannot effectively withstand radial stress or torque.
Innovation Solution
A semiconductor pressure sensor design featuring a through-opening in the substrate with a pressure responsive structure suspended by flexible elements, filled with an anelastic material to decouple stress from the inner part, allowing rotation and minimizing the transfer of stress-induced errors, while maintaining fluid sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the pressure sensor uses a rigid housing structure, then mechanical strength is improved, but stress and deformation of the housing increase causing offset errors
Solution Approach 1:
The sensor is divided into an inner part containing the pressure-sensitive element and an outer part forming the housing, connected by flexible elements. This segmentation allows the housing to maintain structural strength while the flexible connections isolate the sensitive inner part from stress and deformation.
Solution Approach 2:
Flexible elements act as intermediaries between the rigid outer housing and the sensitive inner structure. These flexible elements absorb and isolate mechanical stress, preventing it from being transmitted to the pressure-sensitive element while maintaining structural integrity.
2Force
If the sensor housing is made stiff to withstand radial stress, then radial stress resistance is improved, but stress transfer to the pressure sensitive element increases
Solution Approach 1:
The sensor structure is segmented into an outer part that withstands radial stress and an inner part containing the pressure-sensitive element. The flexible elements connecting these parts allow the outer structure to resist radial stress without transmitting it to the sensitive inner element.
Solution Approach 2:
Flexible elements serve as stress-isolating intermediaries between the radially-stress-resistant outer housing and the pressure-sensitive inner element, absorbing radial stress forces and preventing their transmission to the measurement component.
3Stability of the object's composition
If the inner part is rigidly connected to the outer part, then structural stability is improved, but stress from the outer part transfers to the pressure responsive structure
Solution Approach 1:
The sensor is segmented into outer and inner parts connected by flexible elements rather than rigid connections. This allows the outer housing to remain structurally stable while the flexible connections prevent stress transfer that would cause linearity errors in the pressure measurement.
Solution Approach 2:
The connection between outer and inner parts is made dynamic and flexible rather than rigid. The flexible elements can deform elastically under stress, maintaining structural stability of the overall assembly while preventing stress-induced linearity errors by isolating the pressure-sensitive element.
4Measurement precision
If temperature compensation is used to reduce housing deformation errors, then reversible deformation errors are reduced, but irreversible plastic deformation errors remain
Solution Approach 1:
Flexible elements are incorporated into the structure beforehand to cushion and absorb stress. This mechanical cushioning protects the pressure-sensitive element from both reversible and irreversible stress effects, preventing long-term drift caused by plastic deformation of the housing while maintaining temperature compensation capabilities.
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 solution significantly reduces sensitivity to packaging stress, temperature, and humidity-induced errors, minimizing long-term drift and enabling more accurate pressure measurements by isolating the pressure responsive structure from substrate stress, thus improving the sensor's reliability and accuracy.
Implementation Method 1
the through-opening being at least partly filled with an anelastic material such that where the anelastic material prevents the fluid flowing from one side to the other side of the sensor
Implementation Method 2
a number of flexible elements extending from said inner part to said outer part for suspending the inner part within said through-opening; the flexible elements acting as spring elements, which mechanically isolates the inner structure from the rest of the substrate
Data Source
Figure 1~2
Figure 3(a)~3(b)
Figure 4(a)~4(f)
AI summary
A semiconductor pressure sensor (1) comprising: a semiconductor substrate (2) having a through-opening (3) extending from a top surface (4) to a bottom surface (5) of the substrate (2), the through-opening (3) forming a space between an inner part (12) and an outer part (11) of said substrate; a pressure responsive structure arranged on said inner part (12); a number of flexible elements (7, 13) extending from said inner part (12) to said outer part (11) for suspending the inner part (12) within said through-opening (3); the through-opening being at least partly filled with an anelastic material. A method of producing such a semiconductor pressure sensor.