Full silicidation prevention via dual nickel deposition approach

A method comprising:

• forming a high-k/metal gate on a substrate;
• forming a nitride cap on the gate;
• forming an embedded silicon germanium (eSiGe) source/drain region on each side of the gate;
• forming halo/extension regions in the substrate on each side of the gate;
• depositing a first layer including nickel (Ni) or Ni alloy on the source/drain regions;
• performing a first rapid thermal anneal (RTA) at a temperature of 200° C. to 400° C., to form a first silicide;
• removing the nitride cap by dry etching subsequent to the first RTA;
• depositing a second layer including Ni or Ni alloy on the source/drain regions and on the gate, subsequent to removing the nitride cap;
• performing a second RTA at a temperature of 400° C. to 600° C., to form a second silicide,
• wherein a thickness of the first layer including Ni or Ni alloy is 20% to 50% of a combined thickness of the first and the second layers including Ni or Ni alloy, and the combined thickness of the layers including Ni or Ni alloy is 100 nm to 300 nm, and
• wherein, after performing the second RTA, silicide formed in the source/drain regions has a thickness that is greater than silicide formed in the gate.