Silicide structures in transistors and methods of forming

A method comprising:

• etching an opening through a dielectric layer to expose a source/drain region;
• and
• forming a silicide in the opening, the silicide comprising:
• a first portion extending into the source/drain region, the first portion comprising a metal and silicon;
• and
• a second portion over the first portion, the second portion further disposed on a sidewall of the opening, the second portion comprising the metal, silicon, and nitrogen, wherein the silicide further comprises chlorine.

A method comprising:

• exposing a surface of a source/drain region through an opening in a dielectric layer;
• forming a silicide in the opening, wherein forming the silicide comprises:
• performing a first deposition process to form a first titanium-comprising portion of the silicide on a surface of the source/drain region;
• performing a second deposition process to form a second titanium-comprising portion of the silicide on the first titanium-comprising portion, wherein the second deposition process has a higher power, pressure, gas flow, or a combination thereof than the first deposition process;
• and
• depositing a source/drain contact in the opening over the silicide.