High-k/metal gate stacks in gate first and replacement gate schemes

In this work, representative high-k/metal gate MOS-capacitor stacks were fabricated in both gate first and replacement gate integration schemes. Aluminum- and lanthanum- based cap layers (both widely accepted as Vt tuning cap layers in the industry), in addition to TiN metal gate, can tune the effective workfunction towards PMOS and NMOS, respectively. Varying Ti:N stoichiometry in TiN can induce >250 mV change in TiN workfunction. 1 volt separation between NMOS and PMOS was achieved by screening various workfunction materials in replacement gate scheme. Substrate modification during the growth of aluminum was key to achieving void-free aluminum gap fill in narrow gate trenches.