CMOS IR-Transparent Cap for Hermetic MEMS Sensor Packaging
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Solution Overview
Problem
Conventional uncooled IR detectors, such as microbolometers, require mechanical components for calibration, increasing manufacturing complexity and cost, and are difficult to produce in small or compact forms.
Innovation Solution
A CMOS-compatible process is used to integrate MEMS IR detectors within a hermetically sealed CMOS device, utilizing a CMOS in-situ infrared transparent cap to encapsulate the MEMS sensors, reducing manufacturing complexity and enabling cost-effective, compact device production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical components are used for calibration in microbolometers, then calibration functionality is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces mechanical shutters and calibration components with electrical control mechanisms. The MEMS device uses electrostatic actuation to position the movable plate, and calibration is achieved through electrical signals that adjust the position of the movable plate relative to the fixed plate, eliminating the need for mechanical calibration components.
Solution Approach 2:
The patent extracts and removes mechanical calibration components from the system. By using a MEMS structure with movable and fixed plates that can be positioned electrically, the design eliminates mechanical shutters and other calibration hardware, simplifying the overall device architecture.
2Reliability
If mechanical components are used for calibration, then calibration is possible, but manufacturing costs increase
Solution Approach 1:
The patent replaces mechanical calibration systems with electrical control, reducing the need for precision mechanical parts that are expensive to manufacture. The electrostatic actuation system uses standard MEMS fabrication processes, which are more cost-effective than precision mechanical assembly.
Solution Approach 2:
The MEMS structure serves multiple functions: it acts as both the sensing element and the calibration mechanism. The same movable plate that detects physical quantities also performs calibration when positioned in specific locations electrically, eliminating the need for separate calibration components.
3Reliability
If mechanical components are included for calibration, then calibration can be performed, but device size increases
Solution Approach 1:
The patent removes mechanical calibration components entirely, replacing them with an electrically controlled MEMS structure. This extraction of mechanical parts significantly reduces the device volume, as electrical control circuits occupy much less space than mechanical shutters and calibration mechanisms.
Solution Approach 2:
The movable plate is positioned within the cavity formed by the fixed plate, creating a nested structure. The MEMS device integrates the calibration functionality within the same spatial envelope as the sensing function, maximizing space utilization and minimizing overall device size.
Data Source
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AI summary
A complementary metal oxide semiconductor (CMOS) device 115 embedded with micro-electromechanical system (MEMS) components in a MEMS region. The MEMS components, for example, are infrared (IR) thermosensors. The device 115 is encapsulated with a CMOS compatible IR transparent cap 280 to hermetically seal the MEMS sensors in the MEMS region. The CMOS cap 280 includes a base cap 281 with cap release openings 284 and a seal cap 284 which seals the cap release openings 285.