Subsampling phase retrieval for rapid thermal measurements of heated microstructures

Area of Science:

• Optics and Photonics
• Materials Science
• Thermal Engineering

Background:

• Microelectronic interconnects generate heat, impacting performance and reliability.
• Real-time monitoring of thermal signals is crucial for advanced diagnostics.
• Existing phase retrieval methods can be too slow for high-speed thermal events.

Purpose of the Study:

• To demonstrate a subsampling technique for rapid phase retrieval of high-speed thermal signals.
• To enable precise temperature measurements in microelectronic components.
• To improve the speed and accuracy of thermal analysis in microscale systems.

Main Methods:

• Utilized a Mach-Zehnder interferometer with a microscope objective and high-speed camera.
• Generated thermal signals in aluminum resistors via electrical current.
• Measured refractive index changes to retrieve phase and calculate temperature.

Main Results:

• Achieved a phase analysis speed at least 60x faster than current state-of-the-art methods.
• Maintained a spatial phase noise of 16 nm, comparable to existing techniques.
• Successfully distinguished temperature changes as small as 2 K for slow signals.

Conclusions:

• The demonstrated subsampling technique offers a significant speed improvement for real-time thermal signal analysis.
• The method is suitable for monitoring high-speed thermal events in microelectronic interconnects.
• Potential for future development into fast thermal tomography with system enhancements.