Sacrificial pre-metal dielectric for self-aligned contact scheme

摘要

Various embodiments herein relate to formation of contact etch stop layers in the context of forming gates and contacts. In certain embodiments, a novel process flow is used, which may involve the deposition and removal of a sacrificial pre-metal dielectric material before a particular contact etch stop layer is formed. An auxiliary contact etch stop layer may be used in addition to a primary etch stop layer that is deposited previously. In certain cases the contact etch stop layer is a metal-containing material such as a nitride or an oxide. The contact etch stop layer may be deposited through a cyclic vapor deposition in some embodiments. The process flows disclosed herein provide improved protection against over-etching gate stacks, thereby minimizing gate-to-contact leakage. Further, the disclosed process flows result in wider flexibility in terms of materials and deposition conditions used for forming various dielectric materials, thereby minimizing parasitic capacitance.

主权项

1. A method of forming gates and contact cavities, the method comprising:
(a) forming a plurality of dummy gate structures on a substrate, each dummy gate structure comprising (i) a capping layer, (ii) a layer comprising silicon positioned under the capping layer, and (iii) a spacer layer in contact with vertical sidewalls of the capping layer and the layer comprising silicon; (b) depositing a primary contact etch stop layer over the dummy gate structures and over an active region on the substrate; (c) depositing a sacrificial pre-metal dielectric material in a plurality of gaps positioned between adjacent dummy gate structures; (d) removing the capping layer and the layer comprising silicon from the dummy gate structures; (e) depositing a plurality of replacement metal gates comprising a metal structure and a cap layer positioned over the metal structure, wherein the replacement metal gates are deposited in spaces previously occupied by the capping layer and the layer comprising silicon of the dummy gate structures; (f) removing the sacrificial pre-metal dielectric material; (g) depositing an auxiliary contact etch stop layer, wherein the auxiliary contact etch stop layer is in physical contact with the primary contact etch stop layer, the spacer layer, and the cap layer of the replacement metal gate; (h) depositing replacement dielectric material over the auxiliary contact etch stop layer, wherein the replacement dielectric material is deposited in gaps between adjacent replacement metal gates and over the replacement metal gates; and (i) etching through the replacement dielectric material, the auxiliary contact etch stop layer, and the primary contact etch stop layer to expose the active region below the primary contact etch stop layer and between the adjacent replacement metal gates, thereby forming the contact cavities.