Hybrid airgap structure with oxide liner

摘要

A technique relates to an airgap structure. A dielectric layer is formed on an underlying layer. Copper filled trenches are formed in the dielectric layer, and a metal liner lines the copper filled trenches. An oxide liner lines the metal liner and covers the dielectric layer. One or more airgaps are formed between the copper filled trenches in areas in which the oxide liner was not present on the dielectric layer. A cap layer is formed on top of the one or more airgaps, the copper filled trenches, and portions of the oxide liner.

主权项

1. A method of forming an airgap structure, the method comprising:
patterning trenches into a dielectric layer formed on an underlying layer; disposing an oxide liner on top of the dielectric layer and in the trenches; disposing a metal liner on top of the oxide liner, such that the metal liner lines the trenches; disposing a copper layer on top of the metal liner such that the trenches are filled with the copper layer; planarizing the copper layer to be coplanar with the oxide liner, such that the copper layer remaining forms copper filled trenches with the metal liner; disposing a first cap layer on top of the copper filled trenches and the oxide liner, wherein the first cap layer is a sacrificial or permanent cap layer; disposing a stack of sacrificial layers on top of the first cap layer; patterning an opening into a top sacrificial layer of the stack of sacrificial layers; etching the stack of sacrificial layers, the first cap layer, the metal liner, and the oxide liner according to a pattern of the opening, wherein an airgap pattern is formed in locations where the oxide liner is etched, wherein the airgap pattern leaves one or more exposed portions of the dielectric layer between the copper filled trenches; removing the stack of sacrificial layers; forming one or more airgaps between the copper filled trenches, wherein the one or more airgaps are formed by removing the one or more exposed portions of the dielectric layer between the copper filled trenches; and disposing a second cap layer on top of the one or more airgaps, the copper filled trenches, and portions of the oxide liner.