Micromechanical Pressure Sensor Wafer Bonding
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Solution Overview
Problem
Conventional micromechanical pressure sensors face challenges in integration with inertial and magnetic sensors due to different manufacturing processes and packaging requirements, leading to increased costs and complexity, particularly because they require media access, which complicates their miniaturization and functional integration in consumer electronics.
Innovation Solution
A micromechanical pressure sensor device design that integrates two pressure detection electrodes within a MEMS system capped by an ASIC system, with a diaphragm area in the first micromechanical functional layer and a stationary pressure detection electrode in the second layer, featuring a bond connection that separates electrical contacts from the diaphragm area, reducing stress coupling and improving sensitivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pressure sensors are integrated with inertial and magnetic sensors in a single device, then functional integration and space requirements are improved, but manufacturing complexity and packaging difficulty increase due to different MEMS processes and media access requirements
Solution Approach 1:
The device is divided into two separate wafers: a first wafer containing the pressure sensor with media access, and a second wafer containing inertial and magnetic sensors. This segmentation allows each sensor type to be manufactured using its optimal MEMS process while enabling integration through wafer bonding, thus resolving the conflict between functional integration and packaging complexity
Solution Approach 2:
The patent implements a nested structure where the second wafer (containing inertial and magnetic sensors) is bonded onto the first wafer (containing the pressure sensor). This nesting approach allows multiple sensor types to be combined in a compact configuration, achieving functional integration while managing packaging complexity through hierarchical organization
2Measurement precision
If two pressure detection electrodes are integrated in separate micromechanical functional layers, then sensitivity and measurement precision are improved, but stress coupling and bending effects increase
Solution Approach 1:
A bond connection structure serves as an intermediary between the first and second micromechanical functional layers. This bond connection is designed to mechanically connect the layers while electrically isolating the pressure detection electrodes, thereby reducing stress coupling and bending effects between the electrodes while maintaining the sensitivity benefits of dual-electrode configuration
Solution Approach 2:
The patent extracts the electrical contact function from the mechanical structure by using the bond connection as a mechanical support that does not provide electrical connectivity to the pressure detection electrodes. This separation allows the electrodes to be positioned in separate layers for improved sensitivity while eliminating the harmful stress coupling that would result from direct 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 enhances sensitivity, reduces offset, and improves stability by minimizing bending effects and stress coupling, enabling cost-effective and robust integration with other sensors, such as acceleration and magnetic field sensors, for applications like navigation.
Implementation Method 1
at least one MEMS wafer and one evaluation ASIC wafer are mechanically and electrically connected to one another by way of wafer bonding processes
Implementation Method 2
pressure sensors often make use of piezoresistive resistors for the evaluation
Data Source
AI summary
A micromechanical pressure sensor device and a corresponding manufacturing method. The micromechanical pressure sensor device includes an ASIC wafer having a front side and a rear side, and a rewiring system, formed on the front side of the ASIC wafer, which includes a plurality of stacked strip conductor levels and insulation layers. The pressure sensor device also includes a MEMS wafer having a front side and a rear side, a first micromechanical functional layer which is formed above the front side of the MEMS wafer, and a second micromechanical functional layer which is formed above the first micromechanical functional layer.