Contacts to semiconductor substrate and methods of forming same

A semiconductor structure including a contact to a semiconductor substrate, the contact comprising:

• a contact opening in a dielectric layer over the semiconductor substrate;
• a first liner layer substantially coating a sidewall of the contact opening;
• a refractory metal layer substantially coating the first liner layer in the contact opening;
• a metal substantially filling the contact opening;
• and
• an intermix region at an upper surface of the semiconductor substrate in the contact opening, the intermix region having a composition including a material used in the first liner layer, a material used in the refractory metal layer, and a material used in the semiconductor substrate;
• wherein the refractory metal layer includes a multi-layer having at least a first refractory metal material and a second refractory metal material, the first refractory metal material substantially separating the first liner layer and the second refractory metal material, the second refractory metal material substantially separating the first refractory metal material and the metal.