Dishing-free gap-filling with multiple CMPs

摘要

A method of forming an integrated circuit structure includes providing a semiconductor substrate; forming patterned features over the semiconductor substrate, wherein gaps are formed between the patterned features; filling the gaps with a first filling material, wherein the first filling material has a first top surface higher than top surfaces of the patterned features; and performing a first planarization to lower the top surface of the first filling material, until the top surfaces of the patterned features are exposed. The method further includes depositing a second filling material, wherein the second filling material has a second top surface higher than the top surfaces of the patterned features; and performing a second planarization to lower the top surface of the second filling material, until the top surfaces of the patterned features are exposed.

主权项

1. A method comprising:
etching a dielectric layer to form an opening: forming a diffusion barrier layer, wherein the diffusion barrier layer comprises:
a first portion lining a bottom and sidewalls of the opening; anda second portion overlapping the dielectric layer, wherein the second portion extends horizontally and in contact with a top surface of the dielectric layer; filling a first conductive material in the opening, wherein a first top surface of the first conductive material is higher than the top surface of the dielectric layer; performing a first chemical mechanical polish (CMP) on the first conductive material to form a conductive line in the opening, wherein the conductive line comprises a top surface having a dish, wherein in the first CMP, the second portion of the diffusion barrier layer is used as a CMP stop layer; and filling a second conductive material in the dish, wherein a second top surface of the second conductive material is higher than a top surface of the dielectric layer, wherein the second conductive material comprises a portion overlapping a portion of the dielectric layer, with the portion of the second conductive material comprising a bottom surface in contact with a top surface of the second portion of the diffusion barrier layer.