A method of manufacturing an integrated circuit device includes: doping a substrate with a first type dopant to form a well region; forming a first semiconductor fin and a second semiconductor fin wider than the first semiconductor fin over the well region; forming a first source/drain region of a second type dopant on the first semiconductor fin, the second type dopant is of a different conductivity type than the first type dopant; forming a second source/drain region of the first type dopant on the second semiconductor fin.