V. Quintard

Laser beam thermography of circuits in the particular case of passivated semiconductors

Abstract Surface temperature changes upon integrated circuits can be observed by measuring the corresponding reflectance variation. We presented this method for temperature measurement in earlier work [1, 2] for Si integrated circuits with no passivation layer. We show in this presentation how the passivation oxide layer upon integrated circuits increases, with a factor depending upon the oxide thickness, the reflectance response resulting from a temperature change. Absolute temperature changes are derived from reflectance measurements through a temperature coefficient. This coefficient, known for silicon, is calculated for different oxide thickness.s. We have built a laser probe for reflectance measurements upon integrated circuits. The probe, which includes a visualisation set-up, has a lateral resolution of 1 μm, the size of the laser spot. Absolute temperature changes from 0.05 to 500 K can be determined and followed as a function of time as the detection system covers the DC-125 MHz range. The laser probe allows also the precise measurement of the oxide thickness upon the semiconductor component. This is performed through the measurement of the reflectance at two different angles of incidence.

Laser probing of thermal behaviour of electronic components and its application in quality and reliability testing

Abstract We have developed two optical laser probes for the contactless characterisation of microelectronic components and ICs. The first is a high resolution interferometer for the measurement of dilatations, absolute values over 11 decades are obtained ranging from 10 -3 to 10 -14 m. The second is a reflectance probe for the absolute measurement of surface temperature variations upon ICs. The instrument is a thermometer for surface micrometric analysis able to measure temperature variation in the 10 -3 to 500 °K range. The outstanding performances of these probes have been the starting point of the development of new investigation methods in the field of quality and reliability measurements. We show results of hot points detection upon integrated circuits with micrometric lateral resolution. We also present a method for homogeneity analysis of current density inside power MOS transistors. Finally we present a method for absolute temperature mapping upon metallic lines used in accelerated tests of current stress to study their reliability with regard to electromigration.

Thermoreflectance measurements of transient temperature upon integrated circuits : application to thermal conductivity identification

An analytical 2D study, based on the method of integral transform, for transient heat transfer in a multilayered structure, and an optical technique for transient temperature measurement have been developed. Their application to the case of Joule heating of micrometric interconnections on submicron insulation layers permits one to identify thermophysical properties of the materials involved.

Modelling and experimental study of heat deposition and transport in a semiconductor laser diode

Abstract An analytical model of heat transport in a laser diode is presented together with measurements of the temperature distribution by photothermal microscopy. Comparison between model and measurements shows the temperature distribution to be issued from a cylindrical heat source diffusing in the surrounding bulk material. Laser output facet heating by stimulated photon absorption is shown to be of negligible importance.

Laser probe measurements of quality evolution of solder joints during thermal cycling ageing tests

We present the results of a non-destructive measuring method allowing us to characterize the evolution of solder joints during thermal cycling ageing tests. The method uses a high resolution optical probe to detect selectively pure Joule and Peltier thermal responses of the solder joint subject to a given current pulse. The results show the Peltier and Joule responses to be good indicators for the evaluation of the age and the degradation of solder joints.