Hybrid MEMS-ASIC Capacitor Electrode Relocation
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Solution Overview
Problem
Existing hybrid integrated components with MEMS elements have low capacitance sensitivity due to large electrode gaps, requiring high voltages for activation and lacking a third electrode level for differentiated signal detection.
Innovation Solution
The movable electrode of the capacitor system is relocated from the MEMS structure to the ASIC level, allowing for smaller electrode distances and enabling differential capacitor systems with multiple electrode levels, increasing capacitance and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the capacitor system uses electrodes positioned on the lower side of the MEMS element and in the uppermost metal level of the ASIC element, then the component structure is simple, but the electrode gap is large resulting in low capacitance and low measuring sensitivity
Solution Approach 1:
The patent transitions from a two-dimensional planar electrode arrangement to a three-dimensional stacked configuration. The movable electrode is positioned on the upper side of the MEMS element while the stationary electrode is in the lowermost metal level of the ASIC element, creating a vertical arrangement that reduces the electrode gap distance and increases capacitance without complicating the overall device structure
Solution Approach 2:
The patent changes the positional parameters of the electrodes within the capacitor system. By relocating the movable electrode to the upper side of the MEMS element and the stationary electrode to the lowermost metal level of the ASIC element, the electrode gap distance is reduced, which directly increases the capacitance value and measuring sensitivity
2Measurement precision
If the electrode gap is reduced to increase capacitance, then measuring sensitivity improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent performs preliminary positioning actions during the wafer bonding process. The MEMS element and ASIC element are aligned and bonded at the wafer level before individual component separation, ensuring precise electrode alignment is achieved through the bonding process itself rather than requiring additional high-precision alignment steps later
Solution Approach 2:
The patent uses the wafer bonding process as an intermediary mechanism to achieve precise electrode alignment. The bonding process itself serves as the alignment tool, using the wafer-level structures and bonding interfaces to automatically position the electrodes at the optimal distance without requiring external alignment equipment or complex adjustment mechanisms
3Adaptability or versatility
If a third electrode level is added for differentiated signal detection, then signal detection capability improves, but the device complexity increases
Solution Approach 1:
The patent makes the capacitor system multi-functional by enabling it to perform both actuation and differentiated signal detection. The same capacitor structure with its electrode arrangement can operate as an actuator for moving the micromechanical structure and simultaneously function as a differential sensor for detecting external accelerations, eliminating the need for separate electrode levels for different functions
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 measuring sensitivity and allows for precise detection and activation of micromechanical structures with improved capacitance, suitable for contactless sensors like acceleration and inertial sensors.
Implementation Method 1
the capacitor system includes at least one movable electrode and at least one stationary electrode... the capacitance of the capacitor system is inversely proportional to the distance between the opposing electrodes
Implementation Method 2
at least one electrode of the capacitor system is mechanically and electrically connected to the deflectable structural element of the MEMS element
Data Source
AI summary
Hybrid integrated components including an MEMS element and an ASIC element are described, whose capacitor system allows both signal detection with comparatively high sensitivity and sensitive activation of the micromechanical structure of the MEMS element. The hybrid integrated component includes an MEMS element having a micromechanical structure which extends over the entire thickness of the MEMS substrate. At least one structural element of this micromechanical structure is deflectable and is operationally linked to at least one capacitor system, which includes at least one movable electrode and at least one stationary electrode. Furthermore, the component includes an ASIC element having at least one electrode of the capacitor system. The MEMS element is mounted on the ASIC element, so that there is a gap between the micromechanical structure and the surface of the ASIC element. According to the invention, at least one electrode of the capacitor system is separated from the layered structure of the ASIC element and instead mechanically and electrically connected to the deflectable structural element of the MEMS element, so that this electrode functions as a movable electrode of the capacitor system.