Atomically flat La-silicate/Si interface using tungsten carbide gate electrode with nano-sized grain

Interface properties of La-silicate gate dielectrics on Si substrates with W or nano-sized grain W2C gate electrodes have been investigated. A low interface state density of 2.5 × 1011 cm−2/eV has been achieved with W2C gate electrodes, which is one third of those with W gate electrode. An interface roughness of 0.33 nm with spatial frequency comparable to the grain size of W gate electrode has been observed. Besides, an atomically flat interface of 0.12 nm has been obtained with W2C gate electrode. The origin of flat interface may be attributed to the elimination of inhomogeneous stress by grains in metal electrode