Integrating MEMS and Magnetic Sensors on Single Semiconductor Chip
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Solution Overview
Problem
Existing sensors, such as MEMS and magnetic field sensors, face challenges with size, sensitivity, cost, and integration with semiconductor devices, particularly due to different fabrication processes and alignment issues, necessitating a method to integrate multiple sensors on a single chip without increasing manufacturing complexity or cost.
Innovation Solution
The integration of MEMS sensors and magnetic sensors on a single chip using a cap wafer bonding process, where MEMS sensors are fabricated first, followed by forming through-silicon vias and a metal redistribution layer, and then depositing an oxide isolation layer to accommodate magnetic sensors, allowing for high-temperature processing without damaging the magnetic sensor components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If MEMS sensors and magnetic sensors are integrated on a single chip, then device size is reduced and manufacturing cost decreases, but fabrication process complexity increases due to different process requirements
Solution Approach 1:
The integration process is segmented into distinct sequential stages: first fabricating MEMS sensors on the substrate, then forming through-silicon vias and metal redistribution layers, depositing oxide isolation layers, and finally fabricating magnetic sensors. This segmentation allows each sensor type to be manufactured with its optimal process parameters while maintaining overall integration.
Solution Approach 2:
MEMS sensors are fabricated in advance on the substrate before magnetic sensors are added. The substrate undergoes preliminary processing including through-silicon via formation and metal layer deposition to prepare for subsequent magnetic sensor integration, ensuring that high-temperature magnetic sensor fabrication does not damage previously formed MEMS structures.
2Manufacturing precision
If high-temperature processing is used for magnetic sensor fabrication, then magnetic sensor performance is improved, but previously fabricated MEMS sensor components may be damaged
Solution Approach 1:
MEMS sensors and their protective structures are fabricated in advance before high-temperature magnetic sensor processing. The oxide isolation layer is deposited over the substrate before magnetic sensor fabrication, providing thermal protection to underlying MEMS components during high-temperature magnetic sensor processing.
Solution Approach 2:
An oxide isolation layer is introduced as an intermediary protective barrier between the substrate/MEMS sensors and the magnetic sensor fabrication process. This oxide layer withstands high temperatures and protects underlying sensitive MEMS structures from thermal damage during magnetic sensor processing.
3Area of stationary object
If multiple sensors are integrated on a single chip, then layout efficiency is improved and area is reduced, but alignment precision between different sensor types becomes more difficult to achieve
Solution Approach 1:
Both MEMS sensors and magnetic sensors are merged onto a single substrate, sharing common fabrication infrastructure and alignment references. The through-silicon via formation and metal redistribution layer processes provide common alignment references that ensure precise axis alignment between different sensor types.
Solution Approach 2:
The fabrication process utilizes controlled parameter changes including precise via dimensions, metal layer thicknesses, and oxide layer properties to ensure accurate alignment and positioning of magnetic sensors relative to MEMS sensors on the same chip.
Data Source
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AI summary
In some embodiments a method of manufacturing a sensor system can comprise forming a first structure having a substrate layer (28) and a first sensor (30,32,34) that is positioned on a first side of the substrate layer, bonding a cap structure (24) over the first sensor on the first side of the substrate layer, and depositing a first dielectric layer (131) over the cap structure. After bonding the cap structure and depositing the first dielectric layer, a second sensor (124,126,128) is fabricated on the first dielectric layer. The second sensor includes material that would be adversely affected at a temperature that is used to bond the cap structure to the first side of the substrate layer.