In a method for forming FinFETs, a photo resist is formed to cover a first semiconductor fin in a wafer, wherein a second semiconductor fin adjacent to the first semiconductor fin is not covered by the photo resist. An edge of the photo resist between and parallel to the first and the second semiconductor fins is closer to the first semiconductor fin than to the second semiconductor fin. A tilt implantation is performed to form a lightly-doped source/drain region in the second semiconductor fin, wherein the first tilt implantation is tilted from the second semiconductor fin toward the first semiconductor fin.