Towards an Ultra-Sensitive Temperature Sensor for Uncooled Infrared Sensing in CMOS⁻MEMS Technology

Area of Science:

• Physics
• Electrical Engineering
• Materials Science

Background:

• Microbolometers are key for infrared sensing but have nonlinearity and low temperature sensitivity.
• Complementary metal-oxide semiconductor (CMOS) and Micro-Electro-Mechanical Systems (MEMS) technologies offer advantages but require improvements.

Purpose of the Study:

• To solve nonlinearity issues in microbolometers.
• To demonstrate ultra-sensitive CMOS-MEMS temperature sensors for infrared applications.
• To achieve a significant improvement in temperature sensitivity.

Main Methods:

• Operating the sensor near the beam bending point to resolve nonlinearity.
• Analyzing pull-in force and dimensional changes.
• Utilizing COMSOL multiphysics solver and theoretical analysis.

Main Results:

• A 31x improvement in absolute frequency shift with ambient temperature change was verified.
• Nonlinearity was resolved by operating near the beam bending point.
• Optimum structure derived with 57 µm length and 1 µm thickness, minimizing pull-in force.

Conclusions:

• The developed CMOS-MEMS sensor offers a reliable solution for nonlinearity and ultra-high sensitivity in IR sensing.
• The findings provide guidance for state-of-the-art microbolometer designs.
• Good agreement between theoretical and COMSOL simulations validates the approach.