Thermoreflectance CCD Imaging of Self-Heating in Power MOSFET Arrays

Thermoreflectance imaging with high spatial resolution is used to inspect self-heating distribution in active high power (4A) metal-oxide-semiconductor field-effect transistor transistor arrays designed for high-frequency (MHz) operation. Peak temperature change and self-heating distribution is analyzed for both low- and high-dc bias cases and for different ambient die temperatures (296-373 K). Thermoreflectance images reveal temperature nonuniformity greater than a factor of two over the full area of the transistor arrays. Thermal nonuniformity is revealed to be strongly dependent on both bias level and ambient die temperature. Verification based on the fine grain power dissipation in the transistor array was performed using the R3D method for electrical simulation and power blurring for thermal simulation. Results demonstrate thermoreflectance imaging as an effective tool for fast submicrometer noncontact thermal characterization of active power devices.