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In this paper we present an experimental and theoretical study of the thermoreflectance response as a function of the probe wavelength for layered microelectronics structures. The investigated sample consists of a polycrystalline silicon conducting track grown on a SiO2-coated Si substrate. Thermoreflectance measurements were carried out in the wavelength range from 450 to 750 nm with the track biased in modulated regime. An oscillating pattern is observed in the spectral region where the upper layer is transparent. Such oscillations are due to the interference resulting from the multiple reflections at the interfaces. Using a thermo-optical model, we show that the optical constants (n and k) of the materials, which are wavelength dependent, as well as their temperature derivatives (dn/dT and dk/dT), strongly influence the thermoreflectance signal. The optical thicknesses of the layers, mainly determined by the real part of the refractive indices, define the period of oscillation. On the other hand, the imaginary part of the refractive indices establishes the cutoff wavelength of the oscillations. Below this cutoff wavelength, the probe light does not penetrate the material and the upper-surface reflectance dominates the signal. [ABSTRACT FROM AUTHOR]

We investigated the effect of electrostatic discharge on n-channel metal-oxide-semiconductor field-effect transistors using the thermoreflectance microscopy. The gate terminals of the transistors were submitted to electrostatic pulses on a zap system that respects the human body model. The pulse intensity varied from 40 to 140 V in a cumulative sequence. Electrical characterization showed that the transistor threshold voltage was no longer positive for pulses of 110 V and higher. No significant changes in the thermoreflectance maps were observed in these cases. For pulses of 140 V a large leakage current appeared, and the thermoreflectance maps revealed strong peaks (localized spot) associated with the induced damage. [ABSTRACT FROM AUTHOR]