Origin of tensile stress in the Si substrate induced by TiN/HfO2 metal gate/high-k dielectric gate stack.

The tensile stress induced by the metal TiN film in the atomic layer deposited HfO2/TiN stacks has been found from the crystallite coalescence mechanism of the Volmer–Weber-type growth mode at the early stage of the TiN film formation. The higher tensile stress induced by 3 nm TiN film than that by the 20 nm TiN film resulted from the smaller grain size and the [200] orientation of the TiN layer. Electron energy loss spectrum profile shows that there is no significant elemental interdiffusion between HfO2 and TiN, which could contribute to stress relaxation. [ABSTRACT FROM AUTHOR]