Schottky diode clamping in silicon integrated circuits and distress caused by thermal processing

Aluminum-silicon junctions, such as those used in Schottky T²L and I²L technologies are shown to be sensitive to the heat treatments (HT) encountered in the I.C. processing. The barrier height of Al- nSi clamping diodes φbnincreases with the heat treatment while that of Al- p Si (ohmic) contacts φbpdecreases. The magnitudes of the barrier height changes are dependent upon the HT temperature, Al thickness and cooling rate and can be several tenths of an eV. In-depth Auger analysis of the HT contacts reveals the formation of anoAl-rich (p⁺) surface layer (of Å) which is responsible for the barrier height changes.