Contact etchback in room temperature ionic liquid

摘要

The present disclosure provides an integrated circuit with an interconnect structure and a method for forming the integrated circuit. In one embodiment, a method of the present disclosure includes receiving a workpiece that includes a first recess in a dielectric layer over the workpiece, depositing a contact fill in the first recess and over the dielectric layer to form a contact feature, planarizing a top surface of the workpiece to remove the contact fill over the dielectric layer, depositing an interlayer dielectric layer over the planarized top surface of the workpiece, forming a second recess in the interlayer dielectric layer to expose the contact fill in the dielectric layer, recessing the contact fill by soaking the workpiece in a room temperature ionic liquid, and depositing a conductive layer over the recessed contact fill. The material forming the contact fill is soluble in the room temperature ionic liquid.