MEMS IMU Wiring Layout for Low-Parasitic Signal Detection
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Solution Overview
Problem
Existing MEMS devices face challenges in achieving efficient wiring routing for movable electrodes and fixed electrodes while maintaining high sensor characteristics, leading to issues such as increased area requirements, fluctuations in detection characteristics, and increased costs due to the use of Through Silicon Via (TSV) connections.
Innovation Solution
The MEMS device incorporates a wiring structure provided in the same layer as the movable and fixed electrode portions, with wires routed through an opening part of the movable body via an insulating film, and sets the wiring structure at a fixed potential, such as ground, to minimize parasitic capacitance and fringe electric fields, thereby enhancing wiring efficiency and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Through Silicon Via (TSV) connections are used to route wires to movable and fixed electrodes, then electrical connectivity is achieved, but device area increases and manufacturing cost increases
Solution Approach 1:
The patent extracts the wiring function from the substrate layer and relocates it to the movable body layer. Wires are routed through the movable body to contact movable electrodes, eliminating the need for TSV connections through the substrate. This extraction principle reduces substrate area requirements and simplifies manufacturing by removing complex via structures.
2Reliability
If TSV connections are used for wiring, then electrical connectivity is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The complex TSV manufacturing process is replaced by extracting the wiring function to the movable body layer, where standard planar photolithography and deposition techniques can be used instead of complex via formation and filling processes.
Solution Approach 2:
The wiring structure is segmented into multiple components: wires formed in the movable body, insulating films separating different wire layers, and contact regions. This segmentation allows each component to be optimized and manufactured using appropriate standard processes, reducing overall manufacturing complexity.
3Reliability
If wires are routed through the substrate to reach movable and fixed electrodes, then electrical connectivity is achieved, but parasitic capacitance and fringe electric fields increase
Solution Approach 1:
An insulating film is introduced as an intermediary between the wires and the movable body, and between different wire layers. This intermediary reduces parasitic capacitance by providing electrical isolation while still allowing mechanical support and signal transmission functions to be performed.
4Reliability
If conventional wiring routing is used for movable and fixed electrodes, then device functionality is achieved, but detection precision fluctuates due to parasitic effects
Solution Approach 1:
The insulating film acts as a mediator that reduces parasitic capacitance between wires and electrodes, thereby stabilizing the detection signal and improving measurement precision. The intermediary structure minimizes electric field distortion while maintaining electrical connectivity.
Data Source
AI summary
A MEMS device of an embodiment includes a substrate, fixed electrode portions, a movable body, fixed electrode fixing portions, a wiring structure, and a first wire. The fixed electrode portions are fixed relative to the substrate. The movable body is movable relative to the substrate. The fixed electrode fixing portions are electrically coupled to the fixed electrode portions. The wiring structure is provided in the same layer as those of the movable body and the fixed electrode portions with respect to the substrate. The first wire has one end coupled to the fixed electrode fixing portion. The wiring structure is at least provided in an opening part of the movable body, and the first wire is wired on the wiring structure via an insulating film and routed out of the movable body through the opening part of the movable body.