Interface formation and thermal stability of advanced metal gate and ultrathin gate dielectric layers

The compatibility of metallic titanium nitride (TiNx) films for advanced gate electrodes and remote plasma enhanced chemical vapor deposited silicon oxide (SiO2) or silicon oxide/silicon nitride (Si3N4) advanced gate dielectric layers is investigated by interrupted growth and on-line rapid thermal annealing using on-line Auger electron spectroscopy. Growth of TiNx on SiO2 and Si3N4 occurs uniformly without a titanium seed layer. TiNx/SiO2 and TiNx/Si3N4 interfaces are chemically stable against reaction for rapid thermal annealing treatments below 850 °C. Metal–oxide–semiconductor capacitors using TiNx gate contacts and SiO2 or SiO2/Si3N4 gate dielectrics exhibit excellent C–V characteristics. The measured TiNx/SiO2 barrier height in these devices is Φb=3.7±0.1 eV. The observed difference in fixed charge for SiO2 and SiO2/Si3N4 dielectrics is briefly discussed in terms of a new interface dipole model.