Kevin Moraes

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 >250mV 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.

Advantage of Siconi Preclean over Wet Clean for Pre Salicide Applications Beyond 65nm Node

For advanced devices at 65 nm node and beyond, nickel silicide formed by depositing Ni or its alloys with subsequent annealing has been chosen as the source/drain and gate contact materials. An in-situ dry chemical cleaning technology (Siconi ) has been developed to be integrated with PVD nickel deposition, thus forming a defect-free silicide/Si interface. Queue time related surface contamination and defects caused by using wet (HF) chemical cleaning are thus eliminated. The dry and wet etch methods are compared in this paper in terms of the film Rs, microstructure and thermal stability, as well as the line width effects measured on test wafers.