Kinetics of hillock growth in Al and Al-alloys

Hillock growth kinetics and size distribution were investigated in Al, Al:S i 1% and Al:Si1%:Cu 0.5% layers. Metallization surface was examined by opti cal, SEM and TEM microscopy, stylus profiling and an automatic method of hi llock recognition from a microscope image. The method allowed for counting hillocks in a desired range of their diameter d. Surface density of hillock s was measured as a function of time of furnace annealing at 400 degrees C and as a function of temperature of RTP annealing. A maximum hillock size w as found to increase linearly with metallization layer thickness and with l ogarithm of annealing time. A total area occupied by hillocks was evaluated . Hillock density decreased versus 1/T with an activation energy of 0.28 eV for Al and 0.31 eV for AV:Si. It was found, that a normalized hillock dens ity N may be expressed by a formula N = N-0 exp(-cd). Values for N-0 and c are given together with a short discussion. (C) 2000 Elsevier Science B.V. All rights reserved.