ELECTRON FLOOD APPARATUS FOR NEUTRALISING CHARGE BUILD UP ON A SUBSTRATE DURING ION IMPLANTATION

摘要

An electron flood apparatus for neutralising positive charge build up on a substrate during ion implantation comprises a tube through which the ion beam passes to the substrate. Inert gas is supplied to the plasma chamber and a cathode in the plasma chamber is heated to emit electrons. An accelerating electrical supply is connected betweeen a cathode and an accelerating electrode in the plasma chamber to accelerate electrons emitted by the cathode to produce a plasma in the chamber. A separate cathode bias electrical supply is connected directly between the cathode and the substrate common terminal to set a desired bias potential on the cathode relative to the substrate independently of the acceleration potential.