This mapping technique provides useful information about the power dissipation profile and hot spots related to the design of microelectronics devices. Besides it is also used for the early detection of design, manufacturing or material defects in microelectronics systems.
Appl Phys., 2006; 39: 4153-4166; Optical and thermal image of the heating resistor
The figure illustrates the compare an optical and a thermal image of a five broad polysilicon resistive stripes (heaters). Thanks to this technique it is possible to obtain the temperature map placed at the right of the image. This image results from an accumulation of over 200 heating periods and a total acquisition time of 1 min in practice.
To illustrate the high spatial resolution and the detection of micrometric hot spots the following image also shows the thermal analysis of high power semiconductor laser bars. In this case, it is clearly observed a micrometric hot spot at the face of one emitter (x = 225µm). This permitted the early detection of the ongoing mirror degradation, which eventually leads to catastrophic optical mirror damage failure.
Appl Phys., 2018; 51: 013001
Thermal imaging of an emitter laser bar
The spatial and temperature resolutions and sensitivity reached by thermoreflectance techniques are excellent, however, the accuracy of the absolute temperature readings is more difficult to evaluate due to the lack of comparable thermal techniques with submicrometric spatial resolution. Therefore, major applications of the technique on the microelectronics field involves analyzing the relative temperature gradients on the surface devices and similar studies such as thermal mapping applications, thermal transport studies, and hot spots analyses.
On the other hand, thanks to the high time resolution, ITT is also used for transient thermal imaging in switching devices or other systems under pulsed operation. This character is normally used to identify buried defects or help to extract the thermal resistance/capacitance network in the device, surrounding regions in the substrate and the package.
Time domain thermoreflectance imaging of a gold heater
The figure shows quick heat diffusion in the device metal on short and long time scale thermal imaging of a 100 micron integrated gold heater using pulsed boxcar averaging. The figure also illustrates how the technique is used to study the transitory heat transmission from the sample to other adjacent components.