Demonstration of a Sub-micron Damascene Cu/Low-k Mechanical Sensor to Monitor Stress in BEOL Metallization

This work reports the results of a mechanical sensor to monitor stress in 100 nm critical dimension Cu interconnects. Existing methodology developed for larger scale Al sensors is discussed and evaluated for Cu/SiO₂ and Cu/Low-k integration schemes. New sensor release methods are then developed and the Cu sensor is demonstrated in single and dual damascene technology. We also demonstrate the sensor is sensitive to process modifications and a viable tool for monitoring stress in the Cu back end of line stack.