Patent ID: 8702920

Claim:
An ion source comprising: a plasma generating chamber that is a chamber in which a plasma is generated, which serves as an anode, and in which a source gas is introduced, the plasma generating chamber including an ion extraction port; a cathode that is arranged on the plasma generating chamber and emits electrons inside the plasma generating chamber to ionize the source gas to generate the plasma; and a repeller structure that is arranged facing the cathode in the plasma generating chamber to reflect the electrons toward the cathode, wherein the repeller structure includes a sputtering target that is sputtered by the plasma to emit predetermined ions, the sputtering target including a through hole that connects a sputtering surface and a back surface of the sputtering target; and an electrode that is inserted in the through hole, the electrode including a repeller surface that is exposed to the sputtering surface side through the through hole, wherein the sputtering target and the electrode directly contact each other, and are electrically conductive with respect to each other, and a center of an electron emitting portion of the cathode and a center of the repeller surface are arranged substantially on a same axis, and wherein a magnet is provided outside the plasma generating chamber to generate the magnetic field along a line that connects the cathode to the repeller positioned in the plasma generating chamber, the magnetic field being parallel to the axis in the plasma generating chamber, so as to cause electrons to move back and forth between the cathode and the repeller while circling the magnetic field, with the direction of the magnetic field as its rotating axis, and an ion extraction port is arranged on the plasma generating chamber parallel to the axis.