MEMS Devices with Multi-Pressure Cavities for Sensor Integration
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Solution Overview
Problem
Integrating MEMS pressure sensor, motion sensor, and gyroscope sensor devices into a single integrated circuit manufacturing process poses challenges due to unique electric interconnection requirements.
Innovation Solution
A method for forming MEMS devices with multiple pressure cavities, including low and medium pressure cavities, by bonding wafers and using polysilicon layers for electrical routing and mechanical structures, while controlling dielectric layers for release time and parasitic feedback, allowing for the integration of these sensors within a unified manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple MEMS sensor devices with different pressure requirements are integrated into a single manufacturing process, then device integration and productivity are improved, but manufacturing complexity and process control difficulty increase
Solution Approach 1:
The manufacturing process is segmented into distinct stages: forming first cavities with first pressure (e.g., vacuum) for pressure sensors, then forming second cavities with second pressure (e.g., atmospheric or positive pressure) for motion and gyroscope sensors. This segmentation allows different pressure environments to be created within the same integrated device without requiring separate manufacturing lines.
Solution Approach 2:
Different regions of the MEMS device are assigned different pressure characteristics tailored to their specific functional requirements. Pressure sensor regions experience first pressure conditions, while motion and gyroscope sensor regions experience second pressure conditions, allowing each component to operate in its optimal pressure environment within an integrated structure.
2Adaptability or versatility
If different pressure cavities are formed within the same MEMS device, then functional versatility is improved, but process control and pressure management difficulty increase
Solution Approach 1:
The device is divided into separate cavity systems with independent pressure control. First cavities and second cavities are formed as distinct regions with separate sealing and pressure management, allowing different pressure environments to be maintained simultaneously without interfering with each other.
Solution Approach 2:
Dielectric layers and sealing structures serve as intermediaries between different pressure zones. These intermediary structures enable the formation of multiple pressure cavities within the same device while providing controlled isolation and pressure management for each cavity system.
Data Source
AI summary
Embodiments of the present disclosure include MEMS devices and methods for forming MEMS devices. An embodiment is a method for forming a microelectromechanical system (MEMS) device, the method including forming a MEMS wafer having a first cavity, the first cavity having a first pressure, and bonding a carrier wafer to a first side of the MEMS wafer, the bonding forming a second cavity, the second cavity having a second pressure, the second pressure being greater than the first pressure. The method further includes bonding a cap wafer to a second side of the MEMS wafer, the second side being opposite the first side, the bonding forming a third cavity, the third cavity having a third pressure, the third pressure being greater than the first pressure and less than the second pressure.