Contact Barrier Structure and Manufacturing Methods

A method of forming a semiconductor structure, the method comprising:

• providing a semiconductor substrate;
• forming a gate dielectric over the semiconductor substrate;
• forming a gate electrode over the gate dielectric;
• forming a source/drain region adjacent the gate dielectric;
• forming a metal layer covering at least the source/drain region;
• reacting only a bottom portion of the metal layer with the source/drain region to form a silicide region, wherein a top portion of the metal layer remains after the step of reacting;
• forming an inter-layer dielectric (ILD) over the silicide region and the gate electrode;
• forming a contact in the ILD, wherein the contact is fully situated over, and electrically and directly connected to, the top portion of the metal layer.