Effect of surface NH_(3) anneal on the physical and electrical properties of HfO_(2) films on Ge substrate

摘要

Metal-oxide-semiconductor capacitors were fabricated on germanium substrates by using metalorganic-chemical-vapor-deposited HfO_(2) as the dielectric and TaN as the metal gate electrode. It is demonstrated that a surface annealing step in NH_(3) ambient before the HfO_(2) deposition could result in significant improvement in both gate leakage current and the equivalent oxide thickness (EOT). It was possible to achieve a capacitor with an EOT of 10.5 A and a leakage current of 5.02×10~(-5) A/cm~(2) at 1 V gate bias. X-ray photoelectron spectroscopy analysis indicates the formation of GeON during surface NH_(3) anneal. The presence of Ge was also detected within the HfO_(2) films. This may be due to Ge diffusion at the high temperature (～400℃) used in the chemical-vapor deposition process.