Ion implanter and ion implantation method

An ion implantation method using an ion implanter including a plasma shower device configured to supply electrons to an ion beam with which a wafer is irradiated,

• the plasma shower device including
• a plasma generating chamber provided with an extraction opening from which the electrons supplied to the ion beam are extracted,
• a first electrode which is provided with an opening communicating with the extraction opening and to which a first voltage is applied with respect to an electric potential of the plasma generating chamber, and
• a second electrode which is disposed at a position facing the first electrode in a state where the ion beam is interposed between the first electrode and the second electrode and to which a second voltage is applied with respect to the electric potential of the plasma generating chamber,
• the ion implantation method comprising:
• independently controlling the first voltage and the second voltage according to a beam condition of the ion beam to switch an operation mode of the plasma shower device.