FinFET structure with different fin heights and method for forming the same

A method comprising:

• forming a plurality of first fins and a plurality of second fins protruding over a substrate, wherein:
• two adjacent first fins are separated from each other by a first isolation region;
• and
• two adjacent second fins are separated from each other by a second isolation region;
• applying a first ion implantation process to the first isolation region, wherein p-type dopants are implanted in the first isolation region;
• applying a second ion implantation process to the second isolation region, wherein n-type dopants are implanted in the second isolation region;
• after the first implantation process and the second implantation process, applying an anneal process to the substrate;
• and
• recessing the first isolation region and the second isolation region through an etching process, wherein a top surface of a remaining portion of the second isolation region is higher than a top surface of a remaining portion of the first isolation region, and wherein a height difference between the remaining portion of the second isolation region and the remaining portion of the first isolation region is determined by an etching rate difference between the first isolation region having the p-type dopants and the second isolation region having the n-type dopants.

A method comprising:

• providing a substrate having a plurality of isolation regions;
• applying a first implantation process to the substrate to form an n-type region;
• applying a second implantation process to the substrate to form a p-type region;
• implanting p-type dopants into isolation regions adjacent to the n-type region;
• implanting n-type dopants into isolation regions adjacent to the p-type region;
• after the first implantation process and the second implantation process, applying an anneal process to the substrate;
• and
• recessing isolation regions surrounding the n-type region and the p-type region to form an n-type fin and a p-type fin, wherein:
• the n-type fin is of a first height due to a first etching rate of the isolation region having the p-type dopants;
• and
• the p-type fin is of a second height due to a second etching rate of the isolation region having the n-type dopants, and wherein the first height is greater than the second height, and wherein the first etching rate is higher than the second etching rate.