Aluminum metallization method

Abstract

A metallization method in which a fine interconnection hole is filled with an Al-based material and in which low resistance and excellent barrier properties may be achieved simultaneously, is proposed. The present invention resides in improvement in the barrier metal structure. (a) A stack of a TiSi.sub.2 layer and a Ti layer, formed by an modified SALICIDE method, and (b) a layer of a Ti-based material rendered amorphous are used. The TiSi.sub.2 layer is formed in a self-aligned manner by reacting the silicon substrate with the Ti layer by the interposition of e.g. a thin SiO.sub.2 layer and exhibits lower sheet resistance and dense film properties as well as excellent barriering properties. The Ti layer is stacked on the TiSi.sub.2 layer for improving wettability with respect to the layer of the Al-based material. The layer of the amorphous Ti-based material is formed by N.sub.2 ion implantation into the polycrystalline TiN layer and exhibits superior barrier properties because the crystal grain boundary functioning as the Al diffusion path is destructed. Both of these layers exhibit low sheet resistance as compared to the TiON layer used heretofore as a layer of a material exhibiting excellent barrier properties, while being superior in wettability with respect to the layer of the Al-based material, so that a highly reliable contact may be formed.