A REINTERPRETATION OF THE EXISTENCE OF A SPECTRUM OF ACTIVATION-ENERGIES FOR THE MICROSTRUCTURAL CHANGES IN AL 1-PERCENT SI LINES

During the first thermal treatment after deposition and/or passivation of Al-based interconnects, a marked decrease in the electrical resist ance can be observed. This resistance decrease cannot be described in terms of a single rate constant. Precipitation of the alloyed elements is probably the responsible atomic process. In a previous article, a spectrum of activation energies was extracted in order to characterize this decay. Recent research has shown that the presence of an activat ion energy spectrum is, mathematically, completely equivalent with a s pectrum of pre-exponential factors. Since for precipitation-dissolutio n, the pre-exponential factor is a function of the distribution and ge ometry of the precipitates, the use of a spectrum of pre-exponential f actors is for this specific case probably physically more relevant. Th e technique introduced for the determination of the spectrum of activa tion energies is still valid in case of the presence of a spectrum of pre-exponential factors. (C) 1996 American Institute of Physics.