Thermoreflectance based thermal microscope

Thermal images of active semiconductor devices are acquired and processed in real time using visible light thermoreflectance imaging with 34 mK sensitivity. By using a 16x16 alternating current coupled photodiode array with synchronous frequency domain filtering a dynamic range of 123 dB is achieved for 1 s averaging. Thus with a stable and higher power light source, fundamentally the camera can reach 6 mK sensitivity over a submicron area. The number of pixels in the image is increased to 160x160 by multiple frame image enhancement and submicron spatial resolution is achieved. The photodiode array system has a maximum 40 kHz frame rate and generates a synchronous trigger for recovery of the phase signal. Amplitude and phase images of the thermoreflectance signal for 50x50 micron square active SiGe based microcoolers are presented. (C) 2005 American Institute of Physics.