MEMS Sensor Device with Sealed Reference Chambers
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Solution Overview
Problem
Existing MEMS sensor devices face challenges in providing accurate pressure measurements due to package stress and external factors, which can affect the reliability and accuracy of multiple sensing arrangements packaged together.
Innovation Solution
The implementation of a sensor device with multiple sealed chambers and sensing arrangements, where one chamber provides a vacuum reference pressure and another is exposed to ambient pressure, allowing the top sides of diaphragm regions to be influenced by a second reference pressure, effectively canceling out changes caused by temperature or package stress, thereby ensuring accurate ambient pressure measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple MEMS sensors are packaged together in a single device, then the device can measure different properties (e.g., tire pressure and vehicle acceleration), but package stress and external factors affect the accuracy and reliability of the sensors
Solution Approach 1:
The device is divided into multiple sealed chambers, each housing specific sensing arrangements. The first sealed chamber contains the first pressure sensing arrangement and provides a vacuum reference, while the second sealed chamber contains the second pressure sensing arrangement and provides a second reference pressure. This segmentation isolates each sensor from package stress and external factors, ensuring reliable measurements while maintaining multi-sensing capability
Solution Approach 2:
The patent employs vacuum and controlled pressure environments within sealed chambers to create inert conditions for the pressure sensing arrangements. The vacuum reference chamber eliminates gas interference, while the second sealed chamber maintains a stable pressure environment. This inert environment protection ensures that package stress and external factors cannot interfere with the sensing arrangements, thereby improving measurement reliability
2Device complexity
If a single sealed chamber is used for pressure sensing, then the structure is simple, but package stress and temperature changes cause inaccurate measurements
Solution Approach 1:
Instead of a single sealed chamber, the device uses multiple sealed chambers with different pressure references. The first chamber provides a vacuum reference while the second chamber provides a second reference pressure. This segmentation allows each sensing arrangement to be independently referenced, compensating for package stress and temperature changes, thereby improving measurement precision without excessive complexity
Solution Approach 2:
The patent introduces reference pressure chambers as intermediary elements between the pressure sensing arrangements and the external environment. These reference chambers act as mediators that provide stable reference pressures, allowing the sensing arrangements to accurately measure pressure differences while being isolated from package stress and temperature variations
3Strength
If the sensor device is packaged to protect from harsh environments, then the device durability is improved, but package stress causes deflection of diaphragm regions and measurement errors
Solution Approach 1:
The sensing arrangements are segmented into separate sealed chambers that are isolated from the external packaging environment. This segmentation allows the device to be packaged for protection against harsh environments while the internal chambers maintain stable reference pressures, preventing package stress from causing diaphragm deflection and measurement errors
Solution Approach 2:
The patent employs reference pressure chambers that are sealed beforehand at specific pressures (vacuum and second reference pressure) to cushion against the effects of package stress. These pre-established reference environments compensate for stress-induced diaphragm deflection, ensuring accurate measurements even when the device is packaged for protection
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 enhances the reliability and accuracy of pressure measurements by mitigating the impact of external factors and package stress, allowing the sensor device to operate effectively in harsh environments while maintaining precise sensing capabilities.
Implementation Method 1
a first sealed chamber adjacent to a first side of the first pressure sensing arrangement and having a first reference pressure
Implementation Method 2
a second sealed chamber adjacent to a second side of the first pressure sensing arrangement and the second side of the second pressure sensing arrangement that has a second reference pressure different from the first reference pressure
Implementation Method 3
a first diaphragm region to deflect in response to a difference between the first reference pressure and the second reference pressure
Data Source
AI summary
Apparatus and related fabrication methods are provided for a sensor device. An exemplary sensor device includes a first structure including a first sensing arrangement and a second sensing arrangement formed therein and a second structure affixed to the first structure. The second structure includes a cavity aligned with the first sensing arrangement to provide a first reference pressure on a first side of the first sensing arrangement and an opening aligned with the second sensing arrangement to expose the first side of the second sensing arrangement to an ambient pressure.