Contact metallization process

A method comprising:

• providing a substrate with a source/drain epitaxial layer;
• depositing a dielectric layer over the substrate;
• forming two gate electrodes in the dielectric layer;
• etching an opening in the dielectric layer and between the two gate electrodes to expose the source/drain epitaxial layer;
• forming a first metal layer in the opening and in contact with the source/drain epitaxial layer;
• forming a barrier layer on the first metal layer, wherein the first metal layer and the barrier layer comprise a first metal material;
• and
• forming a metal contact in the opening, wherein the metal contact comprises a liner layer, a second metal layer, and a third metal layer, and wherein the liner layer, the second metal layer, and the third metal layer comprise a second metal material different from the first metal material.

A method, comprising:

• providing a substrate with a field effect transistor (FET);
• forming a dielectric layer over the FET;
• forming an opening in the dielectric layer to expose a source/drain region of the FET;
• forming a first metal layer to partially fill the opening;
• and
• forming a second metal layer over the first metal layer, comprising:
• performing a deposition process by sputtering a target while performing a reflow process by bombarding a surface of the second metal layer with ions;
• and
• adjusting a ratio of a radio frequency (RF) power applied to the target to a direct current (DC) power applied to the target.