Self-aligned silicide (salicide) process for strained silicon MOSFET on SiGe and structure formed thereby

A method of forming a silicide, including:

• providing a substrate to be silicided including forming a metal-silicon mixture over predetermined regions of said substrate;
• reacting said metal-silicon mixture with Si at a first predetermined temperature, to form a metal-rich phase;
• etching any unreacted portion of the metal-silicon mixture;
• depositing a silicon cap over the metal-rich phase;
• annealing the substrate at a second predetermined temperature, to form a metal-Si, alloy;
• and
• selectively etching said unreacted Si.

A method of forming a semiconductor substrate, comprising:

• providing a semiconductor substrate to be silicided including a substrate having a source region and a drain region formed therein on respective sides of a gate;
• forming a metal-silicon mixture over the gate, source and drain regions;
• reacting said metal-silicon mixture with Si at a first predetermined temperature, to form a metal-rich phase;
• etching any unreacted portion of the metal-silicon mixture;
• depositing a silicon cap over the metal-rich phase;
• annealing the substrate at a second predetermined temperature, to form a metal-Si2 alloy;
• and
• selectively etchinu said unreacted Si.

A method of siliciding a substrate, comprising:

• providing a substrate to be silicided forming a metal film over the substrate;
• reacting said metal film with Si at a first predetermined temperature, to form a metal-silicon alloy;
• etching the unreacted metal;
• forming a silicon film over said metal-silicon alloy;
• annealing the substrate at a second predetermined temperature, to form a metal-Si2 alloy;
• and
• selectively etching said unreacted Si.

A semiconductor substrate, comprising:

• a substrate;
• a relaxed Si—Ge buffer layer formed on said substrate;
• a strained silicon layer formed on said Si—Ge buffer layer and having a source and drain formed therein on respective sides of a gate, said gate being formed over said strained silicon;
• and
• a metal film deposited over the gate, source and drain regions, said metal film having been reacted with Si at a first predetermined temperature, to form a metal-silicon alloy,
• wherein said source drain and gate are formed of a metal disilicide, and
• wherein said source and drain are raised over said strained silicon layer.