In order to obtain a dual metal gate, workfunction tuning by various exotic implantations (F, O, Ga, In, C, Er, Se, Al, Sb,...) has been investigated for a fully silicided NiSi gate. According to electrical data, there is no significant breakthrough observed in the NiSi workfunction. However, it seems that some species like Al, Sb and Ga have special interactions with nickel silicide. TEM and SIMS analysis indicate that silicidation is strongly slowed down with Sb implant (<3e15 dose), and in a less extent with Al implants (>5e15 dose). In both cases, the silicidation has been blocked and the polySi gate has not been entirely silicided. On one hand, a uniform but thin NiSi layer was observed with Sb.On the other hand, Auger mapping clearly showed clusters and evidenced lateral phase segregation into NiSi matrix with poly-Si domains. Moreover, for species like Ga, the surface composition would consist mainly of Ni₂Si and NiSi domains with local presence of Ga-precipitates, surrounded by Si-rich halo. This implies that implanted Ga has segregated during/after silicidation anneals, locally affecting silicidation kinetics. The same phenomenon might have appeared for fluorine.

As most exotic species implanted hardly modulate the workfunction, nickel-cobalt alloys formed from bilayers were also investigated for further gate modulation. It was observed that a significant modulation from 4,62eV to 5eV can be achieved, which is interesting for PMOS devices. Thorough electrical and physical characterizations such as SIMS and TEM were used to understand this modulation.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/7962 must be provided.