Ion beam electron neutralizer

Claim 1

An ion implanter for ion beam treatment of workpieces comprising: a) an ion beam source that emits positively-charged ions used in treating the workpieces; b) ion beam forming means comprising structure for forming an ion beam from ions exiting the ion beam source; c) an implantation station comprising structure for positioning workpieces in the ion beam; d) a controller for monitoring ion beam current and controlling dosage of ions impacting the workpieces; and e) a beam neutralizer positioned relative to the ion beam to inject electrons into the ion beam before the ion beam reaches the implantation station including: i) an electrically conductive reflector having a convex surface facing the ion beam for reflecting electrons into the ion beam; ii) an electron source for emitting neutralizing electrons into a region between the convex surface of the reflector and the electron source; iii) a first conductive grid spaced from the electron source for accelerating electrons entering the region between the convex surface of the reflector and the electron source toward the convex surface of the reflector; iv) a second conductive grid spaced from the convex surface of the reflector in the region between the convex surface of the reflector and the electron source defining a region of electron envelope expansion between said first and second conductive grids and a region of electron reflection between the second conductive grid and the reflector; v) conductive means for decelerating the electrons after they are reflected away from the reflector but before they enter the ion beam; and vi) a power supply for electrically biasing the first and second grids and the reflector with respect to the electron source to cause the electrons to pass through the region of electron envelope expansion and reflect away from the reflector into the ion beam.

Claim 14

A method for introducing negatively charged electrons into an ion beam of positively charged ions before the ion beam reaches a workpiece that is treated with the ion beam comprising the steps of: a) aligning a series of elongated filaments end to end along an axial length of the ion beam and energizing said elongated filaments to cause neutralizing electrons to be emitted; b) inhibiting direct movement of the electrons into the ion-beam while accelerating electrons along diverse directions away from the filaments; c) setting up a region of controlled electric potential through which the electrons pass at constant energy after they are accelerated away from the filaments; and d) deflecting the electrons into the ion beam by positioning a curved electron deflector in their path at a point they leave the region of relatively constant electric potential and biasing the curved deflector to set up an electric field which reflects the electrons along generally parallel paths toward the ion beam.

Claim 15

A method for introducing negatively charged electrons into an ion beam of positively charged ions before the ion beam reaches a workpiece that is treated with the ion beam comprising the steps of: a) aligning a series of elongated filaments end to end along an axial length of the ion beam and energizing said elongated filaments to cause neutralizing electrons to be emitted; b) inhibiting direct movement of the electrons into the ion-beam while accelerating electrons along diverse directions away from the filaments; c) setting up a region of controlled electric potential through which the electrons pass at constant energy after they are accelerated away from the filaments; and d) deflecting the electrons into the ion beam by positioning a curved electron deflector in their path at a point they leave the region of relatively constant electric potential and biasing the curved deflector to set up an electric field which reflects the electrons along generally parallel paths toward the ion beam.