WHISKERS GROWN ON ALUMINUM THIN-FILMS DURING HEAT-TREATMENTS

We studied whisker formation on aluminum (Al) films on silicon substra tes during heat treatments, and investigated the influence of the alum inum film properties and the conditions of the heat treatment on whisk er nucleation and growth. The whiskers, which were confirmed to grow i n single crystals due to thermal stress, tended to form on films conta minated with oxygen and nitrogen. This is because these impurities sup press the Al film grain growth during heat treatment, causing localiza tion of the film stress relief which results in whisker formation. Oxi dizing the atmosphere during heat treatment suppresses the nucleation and growth of whiskers. This indicates that breaking Al surface oxide and/or atom rearrangement through surface diffusion has a critical rol e in the growth process of whiskers. (C) 1996 American Vacuum Society.