Improved CVD aluminum deposition using in-situ sputtered nucleation layers

Superior-quality chemical vapor deposited (CVD) Al films have been achieved using tri-isobutylaluminum (TIBA) on in-situ sputtered nucleation layers. The nucleation layer enhances the growth of CVD Al, resulting in smooth, high-quality films suitable for VLSI application. The use of in-situ sputtered seed layers allows the deposition of CVD Al on SiO₂ without having to expose the wafers to TiCl₄ , which may leave Cl residue and cause corrosion. In addition, the CVD films deposited on a TiN seed layer demonstrate smooth morphology and high conductivity and show no presence of the pinholes or interfacial voids which rendered earlier CVD Al films unusable for VLSI. The TIBA process is done at low temperature of 250°C, and TiN is an accepted barrier metal. The combined TiN/CVD Al process promises a low-cost, high-quality manufacturable process for VLSI metallization