Method of scavenging impurities in forming a gate stack having an interfacial layer

摘要

A multi-layer scavenging metal gate stack, and methods of manufacturing the same, are disclosed. In an example, a gate stack disposed over a semiconductor substrate includes an interfacial dielectric layer disposed over the semiconductor substrate, a high-k dielectric layer disposed over the interfacial dielectric layer, a first conductive layer disposed over the high-k dielectric layer, and a second conductive layer disposed over the first conductive layer. The first conductive layer includes a first metal layer disposed over the high-k dielectric layer, a second metal layer disposed over the first metal layer, and a third metal layer disposed over the second metal layer. The first metal layer includes a material that scavenges oxygen impurities from the interfacial dielectric layer, and the second metal layer includes a material that adsorbs oxygen impurities from the third metal layer and prevents oxygen impurities from diffusing into the first metal layer.

主权项

1. A method of forming a gate structure, comprising:
forming an interfacial layer on a semiconductor substrate; forming a high-k dielectric layer on the interfacial layer; forming a first metal layer over the high-k dielectric layer, wherein the first metal layer includes a first material wherein forming the first metal layer includes depositing the first material selected from the group consisting of titanium-rich TiN and tantalum-rich TaN; scavenging oxygen impurities from the interfacial layer using the first material; forming a second metal layer over the first metal layer, wherein the second metal layer includes a second material; and adsorbing oxygen impurities from at least one layer of a nitrogen-rich material or a carbon-rich material overlying the second metal using the second material; and forming a work function layer over the at least one layer.