Ion implantation method and ion implanter

An ion implantation method comprising:

• preparing a wafer on which a mask is formed, wherein the mask has an opening at a predetermined position in a planar surface on the wafer;
• setting, by a temperature adjustment device, a temperature of a wafer to a first temperature;
• irradiating, by an ion implanter when the wafer is at the first temperature, a first ion beam to the wafer through the opening with an orientation at a predetermined implantation angle condition so as to form a first implantation profile in the wafer;
• setting, by the temperature adjustment device after the ion implanter irradiates the first ion beam to the wafer, the temperature of the wafer to a second temperature that differs from the first temperature;
• and
• irradiating, by the ion implanter when the wafer is at the second temperature, a second ion beam to the wafer through the opening with the orientation at the predetermined implantation angle condition so as to form a second implantation profile in the wafer,
• wherein an ion species of the first ion beam is a same species as an ion species of the second ion beam,
• wherein an energy of the second ion beam is lower than an energy of the first ion beam,
• wherein the first ion beam is adjusted by a beam shaper of the ion implanter such that the first ion beam has a first angle distribution,
• wherein the second ion beam is adjusted by the beam shaper such that the second ion beam has a second angle distribution, and
• wherein the first angle distribution and the second angle distribution satisfy a condition that at least a full width at half maximum component of an angle distribution of an ion beam irradiated to the wafer is on-channeling, when the ion beam is irradiated onto the wafer at the predetermined position on the wafer surface in an incident direction under the implantation angle condition.