Recessing RMG metal gate stack for forming self-aligned contact

摘要

Embodiments of the present invention may include methods of incorporating an embedded etch barrier layer into the replacement metal gate layer of field effect transistors (FETs) having replacement metal gates, as well as the structure formed thereby. The embedded etch stop layer may be composed of embedded dopant atoms and may be formed using ion implantation. The embedded etch stop layer may make the removal of replacement metal gate layers easier and more controllable, providing horizontal surfaces and determined depths to serve as the base for gate cap formation. The gate cap may insulate the gate from adjacent self-aligned electrical contacts.

主权项

1. A method comprising:
forming a first embedded etch stop layer in a gate dielectric layer and a work-function metal layer of a replacement metal gate (RMG) using ion implantation, wherein the first embedded etch stop layer comprises a layer of dopant atoms embedded at a depth below an upper portion of the gate dielectric layer and an upper portion of the work-function metal layer; removing the upper portion of the gate dielectric layer and the upper portion of the work-function metal layer; removing the first embedded etch stop layer to expose a lower portion of the gate dielectric layer and a lower portion of the work-function metal layer; forming a gate electrode on the lower portion of the gate dielectric layer and the lower portion of the work-function metal layer; and forming a gate cap on the gate electrode, the gate cap having an upper surface that is substantially flush with an upper surface of a spacer adjacent to the RMG and an upper surface of an interlevel dielectric (ILD) layer adjacent to the spacer.