FinFET doping methods and structures thereof

A method, comprising:

• forming an interfacial layer over a fin extending from a substrate and forming a gate dielectric layer over the interfacial layer;
• depositing a barrier metal layer over the gate dielectric layer;
• performing a thermal fluorine treatment process, wherein the thermal fluorine treatment process includes:
• flowing a fluorine (F2) gas over the barrier layer at a processing temperature substantially equal to a thermal fluorine treatment temperature;
• and
• responsive to flowing the fluorine (F2) gas over the barrier layer at the thermal fluorine treatment temperature, introducing a plurality of fluorine atoms into a first portion of the barrier metal layer to form a fluorinated barrier metal layer;
• and
• performing a rapid thermal anneal (RTA) process to drive at least some of the plurality of fluorine atoms into the interfacial layer and the gate dielectric layer.

A method of fabricating a semiconductor device, comprising:

• depositing a nitride-containing barrier layer over a high-K gate stack, the high-K gate stack disposed over a fin extending from a substrate;
• flowing a fluorine gas over the semiconductor device at a temperature greater than room temperature, wherein the flowing the fluorine gas forms a conformal fluorinated layer within the nitride-containing barrier layer, and wherein the conformal fluorinated layer includes a plurality of fluorine atoms;
• forming a capping layer over the conformal fluorinated layer;
• after forming the capping layer, performing a rapid thermal anneal process to drive at least some of the plurality of fluorine atoms into the high-K gate stack and into an interfacial layer disposed below the high-K gate stack;
• wherein the nitride-containing barrier layer prevents outgassing of the plurality of fluorine atoms during the rapid thermal anneal process.