Contact etchback in room temperature ionic liquid

A method of recessing a contact on an integrated circuit device, the method comprising:

• receiving a workpiece that includes a contact exposed in a bottom surface of a recess in an interlayer dielectric layer over the workpiece;
• and
• recessing the contact using a room temperature ionic liquid and an oxidizer, wherein the recessing comprises:
• oxidizing a top surface of the contact with the oxidizer, and
• after oxidizing the top surface of the contact with the oxidizer, rinsing the top surface of the contact with the room temperature ionic liquid to remove residues of the oxidizer.

A method of forming a low resistance contact in an integrated circuit device, the method comprising:

• receiving a workpiece that includes a contact exposed in a bottom surface of a recess in an interlayer dielectric layer over the workpiece, wherein the contact is electrically coupled to a gate structure or a source/drain feature of the integrated circuit device;
• recessing a contact fill of the contact by soaking the workpiece in a room temperature ionic liquid, wherein the contact fill is soluble in the room temperature ionic liquid;
• and
• depositing a conductive layer over the recessed contact fill of the contact.