The authors have investigated the morphological evolution of Al whiskers grown by high temperature glancing angle deposition (HT-GLAD). The critical temperature of formation of the Al whisker at a deposition angle of 85 degrees is found to be between 180 and 290 degrees C, and it is much lower than that reported for the Al whiskers grown on a hot tungsten wire by the conventional evaporation technique. The morphology of the whiskers grown at a substrate temperature of 290 degrees C reveals that a significant amount of Al is supplied to the whiskers through their base by surface diffusion and that the diffusion length of adatoms on the side surface of the whiskers reaches approximately 10 mu m. It has also been confirmed that a significant number of Al atoms that have been incorporated into the whiskers move in such a manner that drastic changes can occur in the morphology of the whiskers. HT-GLAD is a potential process for providing nanosized metal whiskers. (c) 2007 American Vacuum Society.