[Application] A method for ion implantation is disclosed which includes decreasing the implant energy level as the implant process is ongoing. In this way, either a box-like profile or a profile with higher retained dose can be achieved, enabling enhanced activation at the same junction depth. In one embodiment, the initial implant energy is used to implant about 25% of the dose. The implant energy level is then reduced and an additional 50% of the dose is implanted. The implant energy is subsequently decreased again and the remainder of the dose is implanted. The initial portion of the dose can optionally be performed at cold, such as cryogenic temperatures, to maximize amorphization of the substrate.