Controlling Fin-Thinning Through Feedback

A method comprising:

• forming a first semiconductor fin protruding higher than first isolation regions on opposite sides of the first semiconductor fin;
• forming a second semiconductor fin protruding higher than second isolation regions on opposite sides of the second semiconductor fin;
• measuring a first fin width of the first semiconductor fin;
• measuring a second fin width of the second semiconductor fin;
• thinning the first semiconductor fin based on the first fin width using a first etching chemical, wherein when the first semiconductor fin is thinned, the second semiconductor fin is also thinned, and a first etching rate of the first semiconductor fin is greater than a second etching rate of the second semiconductor fin;
• and
• forming a dummy gate stack on the first semiconductor fin that has been thinned by the thinning the first semiconductor fin.

A method comprising:

• etching a semiconductor substrate to form a semiconductor region, with sidewalls of the semiconductor region being exposed;
• thinning the semiconductor region;
• after the semiconductor region is thinned, filling trenches on opposing sides of the etched semiconductor region to form isolation regions;
• and
• recessing the isolation regions, so that a top portion of the semiconductor region protrudes higher than the isolation regions to form a first semiconductor fin.