Effect of transparency within a semiconductor on emissivity mapping for thermal profile measurements of a semiconductor device

The paper reports on infra-red (IR) measurements made on silicon and gallium arsenide substrates which are transparent to IR radiation. The work showed that the measured emissivity is dependent on the wafer back-face technology, for example, a gold heat-sink or epoxy attachment. The work also indicated that the measured emissivity for the thermal mapping of a device is a function of the emitted radiation from the front, back face and layer interfaces, as well as internally reflected radiation and will be dependent on the thickness of the semiconductor wafer. Experimental work has shown that the two-temperature emissivity correction method will give a very accurate value of the total surface emissivity received from the sample