The effect of an yttrium interlayer on a Ni germanided metal gate workfunction in SiO2/HfO2

Abstract

In this letter, the tuning of a nickel fully germanided metal gate effective workfunction via a hyperthin yttrium (Y) interlayer at the bottom of the metal electrode was demonstrated on both SiO2 and HfO2. By varying the Y interlayer thickness from 0 to 9.6 nm, a full range of workfunction tuning from 5.11 to 3.65 eV has been achieved on NiGeY/SiO2 stacks. It was also found that the chemical potential of the material that is adjacent to the gate electrode/gate insulator plays an important role in the determination of the effective workfunction. This workfunction tuning window was observed to decrease to a range of 5.08-4.25 eV on NiGeY/HfO2 stacks. © 2007 IEEE.