Semiconductor device and method of making the same

A method of forming a semiconductor device, the method comprising:

• forming a fin on a substrate;
• forming a first isolation region surrounding the fin, wherein an upper region of the fin protrudes above the first isolation region and forms a channel region;
• forming a dummy gate structure extending over the first isolation region and the upper region;
• forming a spacer on sidewalls of the dummy gate structure and the upper region;
• epitaxially growing a source/drain region adjacent the upper region;
• performing an etching process on the dummy gate structure to form a recess in and through the dummy gate structure and to remove the upper region underlying the dummy gate structure, wherein after performing the etching process, a fin end of the upper region is formed and protrudes from the spacer into the recess along a fin extending direction in plan view, and portions of the dummy gate structure remain in corner regions defined by the spacer and the fin end of the upper region;
• and
• forming a separation structure in the recess, wherein the remaining portions of the dummy gate structure separate portions of the separation structure from the source/drain region.

A method of forming a semiconductor device, the method comprising:

• forming a fin protruding from a semiconductor substrate;
• forming a dummy gate over the fin;
• forming dummy gate spacers on sidewalls of the dummy gate;
• performing an etching process on the dummy gate to form a recess, wherein the etching process comprises:
• simultaneously etching first portions of the dummy gate at a first etching rate and etching second portions of the dummy gate at a second etching rate that is greater than the first etching rate, wherein each first portion of the dummy gate comprises a first surface over a sidewall of a gate spacer and a second surface over a sidewall of the fin, wherein the second portions of the dummy gate are adjacent the first portions;
• and
• stopping the etching process after the second portions of the dummy gate and at least a portion of the fin under the second portions of the dummy gate are removed, wherein the first portions of the dummy gate remain after stopping the etching process;
• and
• forming a separation structure in the recess, wherein the remaining first portions of the dummy gate structure separate portions of the separation structure from the source/drain region, and wherein the remaining portions protrude from the dummy gate spacers into the separation structure with a distance in plan view in a range from 1 nm to 100 nm.