CMOS-Compatible MEMS Sensor With Hermetic Seal
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Solution Overview
Problem
Existing MEMS sensors require complex processes or non-standard equipment and materials, making them incompatible with the standard CMOS process, which hinders their widespread adoption and integration with CMOS devices.
Innovation Solution
A method for manufacturing a MEMS sensor using a standard CMOS process involves forming interconnections, etching a substrate to create a suspended structure, and using a hermetical package for sealing, allowing for the creation of a compatible MEMS device with a substrate, suspended structure, and upper structure separated by a metal etch, suitable for both absolute and relative sensing applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard CMOS process is used for manufacturing MEMS sensors, then manufacturing compatibility and simplicity are improved, but previously existing MEMS structures cannot be formed
Solution Approach 1:
The patent segments the MEMS sensor manufacturing into distinct CMOS-compatible stages: forming the suspended structure using standard CMOS layers, creating the upper structure separately, and using a hermetical package to seal and integrate them. This segmentation allows each component to be manufactured using standard CMOS processes while maintaining the functional integrity of the complete MEMS sensor.
Solution Approach 2:
The hermetical package serves as an intermediary element that enables the integration of MEMS structures with standard CMOS processes. It provides the sealing and structural support needed for MEMS operation while being compatible with CMOS manufacturing, thus acting as a mediator between the MEMS functional requirements and CMOS manufacturing constraints.
2Reliability
If complex processes or non-standard equipment are used, then MEMS sensor functionality is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent employs universal CMOS manufacturing processes to create MEMS sensors, making the same standard CMOS fabrication lines capable of producing both traditional CMOS devices and MEMS sensors. This multi-functionality eliminates the need for specialized equipment or complex process steps, thereby maintaining sensor functionality while reducing manufacturing complexity.
Solution Approach 2:
The patent utilizes standard CMOS process layers and materials that are already available in high volumes, effectively using readily available, cost-effective resources. By leveraging existing CMOS infrastructure rather than requiring specialized expensive equipment, the approach reduces manufacturing complexity while maintaining reliable sensor functionality.
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 approach enables the production of MEMS sensors fully compatible with the standard CMOS process, facilitating their integration with CMOS devices and enabling the creation of both absolute and relative sensors, such as pressure and acoustical sensors, while maintaining process simplicity and compatibility.
Implementation Method 1
etching the etchable structure
Implementation Method 2
the back side of the substrate can be sealed by hermetical package
Data Source
AI summary
The present invention discloses an MEMS sensor and a method for making the MEMS sensor. The MEMS sensor according to the present invention includes: a substrate including an opening; a suspended structure located above the opening; and an upper structure, a portion of which is at least partially separated from a portion of the suspended structure; wherein the suspended structure and the upper structure are separated from each other by a step including metal etch.