Thermal measurements of active semiconductor micro-structures acquired through the substrate using near IR thermoreflectance

摘要

Modern, high-density integrated circuits (IC) typically use a flip chip bonding technique to increase performance on a greater number of interconnects. In doing so, the active devices of the IC are hidden under the exposed substrate, which precludes the use of typical surface thermal characterization techniques. A near infrared thermoreflectance method is described such that the temperature of active semiconductor devices can be measured through the substrate. Experimental results were obtained through a 200 μm thick silicon substrate. Temperature resolution of 0.1 K and spatial resolution of 5 μm has been achieved. The Fabry-Perot effect, due to multiple reflections between the device and the back of the substrate, has been experimentally and theoretically analyzed. Techniques to enhance the spatial resolution will be discussed