Frederick Plumb

The precision implant 9500 plasma flood system — the advanced solution to wafer charging

Abstract An advanced wafer charge neutralization system based on plasma flood technique has been developed to achieve an ideal voltage control on the wafer surface during implantation. The system makes use of the “self-regulating” characteristics of low energy plasma electrons that clamp the surface potential within a few volts. Low energy electrons are generated in an arc discharge plasma chamber combined with an accel/decel extraction mechanism and are transported to wafers through a guide tube that confines a dense plasma by using a combination of electrostatic suppression and a magnetic cusp field. The system has been equipped as standard on the Precision Implant 9500 and shown full yield on various charge sensitive devices.

Considerations for Advanced Charging Solutions Applied to ULSI Device Fabrication

The control of wafer surface charging during device fabrication becomes increasingly vital as the integration of devices increases. The production of an implantation system with precise charging control involves careful consideration of the configuration of the ion beam optics and process chamber as well as the electron flood system. An understanding of the beam plasma is also important. This paper discusses various requirements for high current ion implanters in terms of solutions to the wafer charging problem.