Methods of fabricating semiconductor device using high-k layer for spacer etch stop and related devices

A method of fabricating a semiconductor device, comprising:

• forming a gate electrode on a substrate;
• forming an inner spacer covering side surfaces of the gate electrode and the substrate;
• forming a shallow junction in the substrate near the gate electrode;
• sequentially forming a buffer layer and an etch stop layer on the inner spacer, the etch stop layer being an insulating layer having a plurality of metal elements;
• forming an outer spacer covering the side surfaces of the gate electrode on the etch stop layer, the etch stop layer being exposed on the shallow junction;
• exposing the buffer layer on the shallow junction by removing the exposed etch stop layer;
• exposing the inner spacer on the shallow junction by removing the exposed buffer layer;
• forming a deep junction in the substrate using the outer spacer as an ion implantation mask;
• removing the outer spacer;
• exposing the substrate by removing the exposed inner spacer;
• and
• forming a metal silicide layer on the deep junction,
• wherein the outer spacer includes a material layer different than the etch stop layer, the buffer layer and the inner spacer.

A method of fabricating a semiconductor device, comprising:

• forming a gate electrode on a substrate;
• forming a buffering layer structure along exposed surfaces of the gate electrode, wherein the buffering layer structure includes at least two buffer layers of which an outermost buffer layer has a dielectric constant higher than at least one inner buffer layer;
• forming a first spacer along side surfaces of the gate electrode and partially exposing the outermost buffer layer, wherein the first spacer includes a material layer different than that of the at least two buffer layers;
• repeatedly exposing the buffering layer structure to sequentially pattern the at least two buffer layers;
• forming a deep junction in the substrate using the first spacer as an ion implantation mask;
• and
• removing the first spacer.