Interdiffusion studies for HfSixOy and ZrSixOy on Si

Metal incorporation into silicon substrates, and thermal stability of alternate gate dielectric candidates ${\mathrm{HfSi}}_x{\mathrm{O}}_y$ and ${\mathrm{ZrSi}}_x{\mathrm{O}}_y$ films after aggressive thermal annealing are reported. Considerable Zr incorporation is observed after furnace and rapid thermal annealing. No detectible Hf incorporation is observed for ${\mathrm{HfSi}}_x{\mathrm{O}}_y$ films annealed with the same conditions as the ${\mathrm{ZrSi}}_x{\mathrm{O}}_y$ films. Sputter deposited Hf silicate films showed superior thermal stability compared with chemical vapor deposited Zr silicate films. An alternate approach to obtain sub-nm resolution depth profiling of impurities in Si is also reported. Device performance associated with Zr incorporation into the channel is also discussed.