High resolution thermal imaging inside integrated circuits

Abstract

Purpose

Heating is a major cause of failure in integrated circuits. The authors have designed thermoreflectance‐based systems operating at various wavelengths in order to obtain temperature images. This paper aims to explore the possibilities of each wavelength range and detail the charge coupled device (CCD)‐based thermal imaging tools dedicated to the high‐resolution inspection of integrated circuits.

Design/methodology/approach

Thermoreflectance is a non‐contact optical method using the local reflectivity variations induced by heating to infer temperature mappings, and can be conducted at virtually any wavelength, giving access to different types of information. In the visible, the technique is now well established. It can probe temperatures through several micrometers of transparent encapsulation layers, with sub‐μm spatial resolution and 100 mK thermal resolution.

Findings

In the ultraviolet range, dielectric encapsulation layers are opaque and thermoreflectance gives access to the surface temperature. In the near infrared, thermoreflectance is an interesting solution to examine chips turned upside down, since these wavelengths can penetrate through silicon substrates and give access to the temperature of the active layers themselves.

Research limitations/implications

The authors show that the illumination wavelength of thermoreflectance should be chosen with care depending on the region of the integrated circuit (surface, above, or below the substrate) to be investigated.

Practical implications

This set of versatile and sensitive tools makes thermoreflectance an interesting tool for the semiconductor industry, either during prototyping or as a characterization tool after fabrication.

Originality/value

The CCD‐based thermoreflectance approach adopted here allows fast, non‐contact, high‐resolution thermal imaging of integrated circuits.

Citation

Tessier, G., Bardoux, M., Filloy, C., Boué, C. and Fournier, D. (2007), "High resolution thermal imaging inside integrated circuits", Sensor Review, Vol. 27 No. 4, pp. 291-297. https://doi.org/10.1108/02602280710821425