Online proceedings - EDA Publishing Association

semiconductors is of the order of 10 -4 , the ΔT sensitivity is afew K. With the point measurement technique, the sensitivityis the best but to the detriment of a very long acquisition time.Hence, we can reach a ΔT sensitivity of 10mK for classicalsemiconductors and surface displacements lower than 10fm.But the time spent for an image is then several hours with anheterodyne interferometric probe and even much more with aclassical Michelson interferometer. Until now, the scanningsystem is limited to thermomechanical studies at frequenciesabove 20 kHz. However, the thermoreflectance andinterferometry sensitivities (0.2K and 10pm) are very goodfor a relative short imaging acquisition time (5 minutes).VI. CONCLUSIONWe presented a fast scanning system for thermomechanicalimaging. We have applied it to the study of two electronicdevices. We have presented thermoreflectance reflectivityrelative variation images and interferometric surfacedisplacement images. Thanks to the use of fast galvanometricmirrors, the system proved to be a good compromise in termsof sensitivity and acquisition time between pointmeasurement and CCD imaging systems. Until now, it islimited to a frequency range above 20kHz but we are nowworking to make it evolve to lower frequency measurements.TABLE IPERFORMANCES OF THERMOMECHANICAL POINT MEASUREMENT, CCD IMAGINGAND SCANNING IMAGING TECHNIQUESTechnique CCD point scanningSpatialresolutionMeasure time by pixel(s)ΔR/R sensitivity(Acquisition time in mn)Displacement sensitivity(Acquisition time in mn)Diffractionlimit15×10 -4(15)1000)1000)ACKNOWLEDGMENTDiffractionlimit