Improvement of threshold voltage deviation in damascene metal gate transistors

The metal gate work function deviation (crystal orientation deviation) was found to cause the threshold voltage deviation (DeltaV(th)) in the damascen e metal gate transistors, When the TiN work function (crystal orientation) is controlled by using the inorganic CVD technique, DeltaV(th) Of the surfa ce channel damascene metal gate (Al/TiN or W/TiN) transistors was drastical ly improved and found to be smaller than that for the conventional polysili con gate transistors. The reason for the further reduction of the threshold voltage deviation (DeltaV(th)) in the damascene metal gate transistors is considered to be that the thermal-damages and plasma-damages on gate and ga te oxide are minimized in the damascene gate process. High performance sub- 100 nm metal oxide semiconductor field effect transistors (MOSFETs with wor k-function-controlled CVD-TIN metal-gate and Ta2O5 gate insulator are demon strated in order to confirm the compatibility with high-k gate dielectrics and the technical advantages of the inorganc CVD-TiN.