Recessing STI to increase FIN height in FIN-first process

A method comprising:

• forming isolation regions extending into a semiconductor substrate, wherein the semiconductor substrate comprises a semiconductor strip located between opposite portions of the isolation region, and the semiconductor strip comprises a first portion and a second portion, and a third portion between the first portion and the second portion;
• recessing the first portion and the second portion of the semiconductor strip to form a first recess and a second recess extending into the isolation region;
• epitaxially growing a source region and a drain region in the first recess and the second recess, respectively;
• recessing first portions of the isolation regions on opposite sides of the source region and the drain region, so that top portions of the source region and the drain region protrude higher than the recessed first portions of the isolation regions;
• and
• recessing second portions of the isolation regions, so that a top portion of the third portion of the semiconductor strip protrudes higher than the recessed second portions of the isolation regions to form a protruding semiconductor fin.

A method comprising:

• forming isolation regions extending from a top surface of a semiconductor substrate into the semiconductor substrate, wherein a portion of the semiconductor substrate between neighboring ones of the isolation regions forms a semiconductor strip;
• forming a dummy gate stack overlapping both of the isolation regions and the semiconductor strip, wherein the semiconductor strip comprises first portions on opposite sides of the dummy gate stack, and a second portion overlapped by the dummy gate stack;
• forming gate spacers contacting sidewalls of the dummy gate stack;
• recessing the first portions of the isolation regions to form first recesses;
• filling an entirety of the first recesses with dielectric layers, wherein the dielectric layers extend to a level lower than a top surface of the semiconductor strip;
• recessing the second portions of the isolation regions to form second recesses, wherein the second recesses are between the gate spacers;
• and
• forming a replacement gate stack extending into the second recesses.