MEMS Device With Blocking Layer For Pressure Control
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Solution Overview
Problem
Existing MEMS devices face challenges in maintaining different pressures within cavities, which affects the sensitivity and functionality of pressure sensors due to gas leakage from dielectric materials, leading to reduced sensitivity and performance.
Innovation Solution
The formation of MEMS devices involves annealing processes to reduce gas content in dielectric layers, using blocking layers to prevent gas penetration, and creating multiple cavities with distinct pressures by bonding substrates with controlled pressure environments, allowing for the integration of MEMS elements with different functions in a single device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dielectric layers are used in MEMS devices, then electrical insulation and structural support are provided, but gas leakage from the dielectric materials reduces vacuum integrity and sensor sensitivity
Solution Approach 1:
A dedicated blocking layer is introduced as an intermediary component between the dielectric layer and the cavity. This blocking layer specifically targets and prevents gas leakage from the dielectric material into the cavity, thereby maintaining vacuum integrity without compromising the electrical insulation and structural support functions of the dielectric layer.
Solution Approach 2:
The harmful gas-permeable property is extracted from the system by separating the gas-blocking function into a distinct blocking layer. This allows the dielectric layer to maintain its primary functions (electrical insulation and structural support) while the blocking layer specifically addresses the gas leakage issue.
2Adaptability or versatility
If multiple cavities with different pressures are created, then diverse MEMS functionalities are enabled, but the complexity of maintaining pressure differential increases
Solution Approach 1:
The device is segmented into multiple independent cavities, each with its own pressure control characteristics. The blocking layers are strategically placed to segment the gas paths, allowing each cavity to maintain its designated pressure independently. This segmentation enables diverse MEMS functionalities in different cavities while simplifying the overall pressure control architecture.
Solution Approach 2:
Different regions of the device (cavities) are assigned different pressure qualities based on their specific functional requirements. The blocking layers create localized gas barrier properties where needed, allowing each cavity to have optimized pressure characteristics without affecting other regions, thereby enabling versatile MEMS functionality with manageable complexity.
3Reliability
If annealing processes are applied to reduce gas content in dielectric layers, then vacuum integrity is improved, but processing time and energy consumption increase
Solution Approach 1:
The blocking layer is incorporated into the device structure during the fabrication process, performing the gas-blocking function proactively before the device operates. This preliminary structural prevention of gas leakage reduces or eliminates the need for extended annealing processes that would otherwise be required to achieve equivalent vacuum integrity, thereby reducing processing energy consumption.
Solution Approach 2:
Instead of relying solely on energy-intensive annealing processes to remove gas from dielectric materials, the design converts the inherent gas-permeable nature of dielectric materials into a manageable characteristic by adding a dedicated blocking layer. This approach transforms the potential harm (gas leakage) into a controlled design parameter, avoiding the need for excessive energy input during processing.
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 enhances the vacuum integrity of closed chambers, improving the sensitivity and functionality of MEMS devices by maintaining distinct pressures and reducing gas interference, thereby enhancing the performance of integrated MEMS elements.
Implementation Method 1
annealing processes to reduce gas content in dielectric layers
Implementation Method 2
blocking layers to prevent gas penetration
Data Source
AI summary
A method for forming a micro-electro mechanical system (MEMS) device is provided. The method includes bonding a semiconductor substrate with a carrier substrate through a dielectric layer and patterning the semiconductor substrate into multiple elements. The method also includes partially removing the dielectric layer to release some of the elements such that the released elements become one (or more) first movable element and one (or more) second movable element. The method further includes bonding a cap substrate with the semiconductor substrate to form a first closed chamber containing the first movable element and a second closed chamber containing the second movable element. In addition, the method includes opening the second closed chamber and sealing the second closed chamber after vacuumizing the second closed chamber such that the second closed chamber has a reduced pressure smaller than that of the first closed chamber.