Richard Siegfried Wagner

Oxidation of silicon without the formation of stacking faults

A new technique of eliminating oxidation‐induced surface stacking faults has been developed. It involves heating clean silicon wafers in an inert or HCl‐inert ambient in the same furnace where subsequent oxidation—wet or dry—will be carried out. Typical fault densities after oxidation without in situ cleaning are 1000–5000 and 50–500/cm2 for n‐ and p‐type wafers; these numbers are reduced to ∼10–100 and 0, respectively, when in situ cleaning is used.

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 SiO/sub 2/ without having to expose the wafers to TiCl/sub 4/, 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 degrees 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.<<ETX>>