Ultrafast submicron thermal characterization of integrated circuits

Static and dynamic hot spots limit the performance and reliability of electronic devices and ICs. We show that transient thermoreflectance imaging using a CCD camera can measure temperature distribution in chips with 0.1°C temperature, 100 nanosecond time, and submicron spatial resolution. It is possible to measure the temperature on metal interconnects in wire-bonded chips and, with through-the-substrate infrared illumination, at the transistor level in flip-chip packages. Recent results in transient thermal imaging of GaN transistors, ESD protection devices, solar cells, and LEDs are presented. We show it is possible to identify non-uniform temperature rise and defects in 200 to 300 nm interconnect vias that have been stressed at high temperatures. Power blurring techniques can be used to obtain transient temperature profiles in packaged IC chips with a calculation time orders of magnitude faster than finite element analysis. The technique is well suited to solve the inverse problem and extract the power dissipation profile from the measured thermal map.