Integrated MEMS Pressure Sensor with ASIC Wafer Bonding
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Solution Overview
Problem
Current micromechanical sensor devices, particularly pressure sensors, face challenges in integration with inertial sensors due to different manufacturing processes and evaluation methods, leading to increased costs and complexity in packaging, which hinders the development of integrated modules for consumer electronics.
Innovation Solution
A method involving the connection of a wafer forming a micromechanical functional layer to an ASIC wafer via an insulating layer, with electrically conductive contact plugs, allowing for the formation of a diaphragm area as a pressure detection electrode and enabling integration of additional sensor devices, such as inertial sensors, while providing a pressure access for the pressure sensor, and using a cap wafer for protection without affecting functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pressure sensors are manufactured separately from inertial sensors, then manufacturing processes and evaluation methods can be optimized for each sensor type, but packaging effort and costs increase due to necessary media access requirements
Solution Approach 1:
The patent combines pressure sensors and inertial sensors into a single integrated sensor device, merging previously separate manufacturing processes and packaging requirements into one unified structure, thereby reducing overall packaging effort while maintaining manufacturing optimization
Solution Approach 2:
The sensor device is designed with multi-functionality to accommodate both pressure sensing (requiring media access) and inertial sensing (requiring sealed encapsulation) within a single package, allowing one packaging solution to serve multiple functional requirements
2Device complexity
If pressure sensors are integrated with inertial sensors in combined modules, then cost reductions and reduced space requirements are achieved, but different MEMS manufacturing processes and evaluation processes must be reconciled
Solution Approach 1:
The patent integrates pressure sensors and inertial sensors in a vertical three-dimensional arrangement within the same substrate, allowing both sensor types to coexist in the same package without interfering with each other's manufacturing processes, thus reducing footprint while maintaining process compatibility
Solution Approach 2:
Different regions of the sensor substrate are optimized for specific sensor types, with local manufacturing processes and evaluation methods tailored to each sensor type's requirements while integrating them into a unified device structure
3Ease of operation
If wafer bonding processes are used for vertical integration, then external contacting can be achieved as bare die module or chip scale package, but process complexity and bonding requirements increase
Solution Approach 1:
The patent performs preliminary structuring and preparation of wafers before bonding, including creating through-wafer vias and bonding surfaces in advance, which simplifies the actual bonding process and reduces complexity during the critical joining step
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 creation of a micromechanical pressure sensor device that can be integrated with other sensors, reducing costs and space requirements, and improving hermeticity and sensitivity, facilitating the development of integrated sensor modules for applications like indoor navigation.
Implementation Method 1
a wafer, which forms the starting point for a micromechanical functional layer, is connected to an ASIC wafer, preferably a CMOS wafer, in an electrically insulated manner via an insulating layer
Implementation Method 2
an electrical connection to the uppermost strip conductor level of the ASIC wafer subsequently being established by one or multiple electrically conductive contact plugs
Implementation Method 3
a diaphragm area is formed in the latter as a first pressure detection electrode
Data Source
AI summary
A micromechanical pressure sensor device and a corresponding manufacturing method. The micromechanical pressure sensor device includes an ASIC wafer, a rewiring system, formed on the front side, which includes a plurality of strip conductor levels and insulating layers situated in between, a structured insulating layer formed above an uppermost strip conductor level, a micromechanical functional layer formed on the insulating layer and which includes a diaphragm area, which may be acted on by pressure, above a recess in the insulating layer as a first pressure detection electrode, and a second pressure detection electrode on the uppermost strip conductor level, formed in the recess at a distance from the diaphragm area and is electrically insulated from the diaphragm area. The diaphragm area is electrically connected to the uppermost strip conductor level by one or multiple first contact plugs which are led through the diaphragm area and through the insulating layer.