Ion implanter

An ion implanter in which a traveling direction of an ion beam is set as a Z direction, two directions which are substantially orthogonal to each other in a plane that is substantially orthogonal to the Z direction are set as X and Y directions, respectively, and a ribbon-like ion beam in which a dimension in the Y direction is larger than a dimension in the X direction is transported to irradiate a substrate, thereby performing ion implantation, said ion implanter comprising:

• an ion source that has one or more filaments for generating an arc discharge in a plasma vessel into which a gas is introduced, and that generates the ribbon-like ion beam in which a Y-direction dimension is larger than a Y-direction dimension of the substrate;
• a substrate driving device which, in an implanting position where the ion beam is caused to be incident on the substrate, moves the substrate in a direction intersecting with a principal face of the ion beam;
• one or more electron beam sources which generate an electron beam, and emit the electron beam into said plasma vessel of said ion source to ionize the gas, thereby producing a plasma, and which scans the electron beam in the Y direction in said plasma vessel;
• one or more electron-beam power sources which supply an extraction voltage for controlling a generation quantity of the electron beam, and a scan voltage for the scan to said electron beam sources;
• an ion beam monitor which, in the implanting position or a vicinity of the position, measures a Y-direction ion beam current density distribution of the ion beam at plural monitor points in the Y direction;
• and
• a controlling device having a function of homogenizing the Y-direction ion beam current density distribution measured by said ion beam monitor, by, while controlling said electron-beam power sources on the basis of measurement data of said ion beam monitor to maintain a scanning speed of the electron beam generated by said electron beam source to a substantially constant value, performing at least one of:
• a relative decrease of the generation quantity of the electron beam in a position in said ion source corresponding to a monitor point where an ion beam current density measured by said ion beam monitor is relatively large;
• and a relative increase of the generation quantity of the electron beam in a position in said ion source corresponding to a monitor point where the ion beam current density measured by said ion beam monitor is relatively small.