Camera-based thermoreflectance microscopy is a unique tool for high spatial resolution thermal imaging of working integrated circuits. However, a calibration is necessary to obtain quantitative temperatures on the complex surface of integrated circuits. The spatial and temperature resolutions reached by thermoreflectance are excellent (360 nm and 2.5 × 10−2 K in 1 min here), but the precision is more difficult to assess, notably due to the lack of comparable thermal techniques at submicron scales. We propose here a Peltier element control of the whole package temperature in order to obtain calibration coefficients simultaneously on several materials visible on the surface of the circuit. Under high magnifications, movements associated with thermal expansion are corrected using a piezo electric displacement and a software image shift. This calibration method has been validated by comparison with temperatures measured using integrated thermistors and diodes and by a finite volume simulation. We show that thermoreflectance measurements agree within a precision of ±2.3% with the on-chip sensors measurements. The diode temperature is found to underestimate the actual temperature of the active area by almost 70% due to the thermal contact of the diode with the substrate, acting as a heat sink.

7 pagesA method for profiling surface objects based on the fringe projection method and a phase shifting algorithm is described. The application of this method to large surfaces is problematic since the calibration step requires the use of a reference plane as large as the object. A new algorithm based on least-squares method has also been developed to bypass this calibration step, and so the use of a reference plane. First experimental results on a carbon panel and on a parabolic aerial are presented to show the validity of the proposed algorithm. Accuracy of 1mm has been obtained for an object of 1m and 20 cm long, while sensitivity has been proved to be of the order of 100 m

We have developed a CCD-based thermoreflectance microscope which can deliver thermal images of working integrated circuits. However, in any thermoreflectance experiment, the coefficient linking reflectance variations to temperature is different for each material. Calibrations are therefore necessary in order to obtain quantitative temperature imaging on the complex surface of an integrated circuit including several materials such as aluminium and polysilicon. We propose here a system using a Peltier element to control the temperature of the whole package in order to obtain calibration coefficients simultaneously on all the materials visible on the surface of the circuit. Under high magnifications, vertical and lateral movements associated to thermal expansion are corrected using respectively a piezo electric displacement and a software image shift. This calibration method has been validated by comparison with the temperatures measured with separately calibrated thermocouples and diodes placed close to the integrated resistors.

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