Sensitivity enhancement in thermoreflectance microscopy of semiconductor devices using suitable probe wavelengths

Abstract

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 450to750nm 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.

Thermography techniques for integrated circuits and semiconductor devices

“…Thermoreflectance microscopy can have single (Dilhaire et al , 2004; de Freitas et al , 2005) or multiple detectors (Christofferson and Shakouri, 2005; Tessier et al , 2001), and has been applied to the study of integrated circuits (Burzo et al , 2005; Mandelis et al , 1988; Tessier et al , 2005a, b). The laser thermoreflectance technique is not only promising for the thermal mapping of the devices, but also the out‐of‐plane (or normal) thermal conductivity measurement of thin films (in the order of 100 nm) (Burzo et al , 2006; Chu et al , 2001).…”

AFM-thermoreflectance for simultaneous measurements of the topography and temperature

“…Consequently, if the thickness of the cantilever and wavelength and angle of the incident laser beam are kept constant, the reectance is then only a function of the temperature of the cantilever. Because the temperature-dependent dielectric function of Si, which is widely used as an AFM probe material, is well characterized, 36,[38][39][40] thermometry is possible with the TR Fig. 1 Concept of the AFM-TR technique.…”

“…1,[13][14][15][16][18][19][20][21][22][23][24][25][26][27] Further, nanoscale thermometry with a high spatial resolution is paramount for accurate thermal characterizations of nanomaterials (e.g., graphene, carbon nanotubes, or nanowires), which have recently drawn enormous amounts of attention. [11][12][13][14][27][28][29][30][31][32][33][34] Related research has been carried out with micro-Raman spectroscopy, 35 thermoreectance (TR), [36][37][38][39][40] near-eld scanning optical microscopy (NSOM), 41 scanning thermal microscopy (SThM), [12][13][14][18][19][20][21][22][23][24][30][31][32][33]…”

Frequency-resolved temperature imaging of integrated circuits with full field heterodyne interferometry

“…2 The knowledge of the time or frequency dependence of the temperature is also essential, as it can allow the localization of transient overheating or of areas working at different multiples of the clock frequency, but has received much less attention. 2 The knowledge of the time or frequency dependence of the temperature is also essential, as it can allow the localization of transient overheating or of areas working at different multiples of the clock frequency, but has received much less attention.…”