Integrated circuit structure and method for fabrication the same

Integrated circuit (IC) structures and methods for forming the same are provided. An IC structure according to the present disclosure includes a substrate, an interconnect structure over the substrate, a guard ring structure disposed in the interconnect structure, a via structure vertically extending through the guard ring structure, and a top metal feature disposed directly over and in contact with the guard ring structure and the via structure. The guard ring structure includes a plurality of guard ring layers. Each of the plurality of guard ring layers includes a lower portion and an upper portion disposed over the lower portion. Sidewalls of the lower portions and upper portions of the plurality of guard ring layers facing toward the via structure are substantially vertically aligned to form a smooth inner surface of the guard ring structure.