Ion implanter and controlling method therefor

A method of controlling an ion implanter comprising:

• extracting an ion from an ion source and forming an ion beam;
• generating secondary electrons in response to ions incident on a secondary electron generating means;
• directing with a negatively biased electrically conducting secondary electron directing means secondary electrons toward a semiconductor substrate;
• implanting ions from the ion beam into the semiconductor substrate;
• turning off the bias applied to the secondary electron directing means when the secondary electron directing means becomes electrically insulating during ion implantation with the ion beam.

An ion implanter comprising:

• a substrate support for supporting a semiconductor substrate;
• scanning means for scanning a semiconductor substrate mounted on the support with an ion beam;
• an electrode surrounding a semiconductor substrate mounted on the support and having a surface disposed to be scanned by the ion beam, secondary electrons being produced in response to ions incident on the electrode;
• means for maintaining the electrode at a negative electrical potential with respect to the substrate support;
• and
• an electron directing member having an electrically insulating surface surrounding a semiconductor substrate mounted on the support and the electrode and disposed to be charged by secondary electrodes generated at the electrode.

An ion implanter comprising:

• a substrate support for supporting a semiconductor substrate;
• a ring-shaped first electrode mounted on the substrate support for surrounding a semiconductor substrate mounted on the support and having a surface substantially parallel to a semiconductor substrate mounted on the support;
• a second electrode having a first portion extending generally parallel to the substrate support and a wall extending substantially perpendicular to the substrate support and surrounding a semiconductor substrate mounted on the support and the first electrode;
• scanning means for scanning a semiconductor substrate mounted on the support and the first electrode with an ion beam;
• and
• means for maintaining the first and second electrodes at different negative electrical potentials with respect to the substrate support.