| 摘要 |
PURPOSE:To prevent a heavy metal contamination of an ion beam irradiated substrate and the thermal radiation to the substrate, by using a photoelectron source combining a light source and a photoelectron screen as an electron source to neutrize the electric charge of an ion radiating device, instead of a conventional thermal electron source with a filament. CONSTITUTION:This device has an electron source which consists of a light source 7 and a photoelectron screen 8 to emit electrons by receiving the light from the light source 7, a drawing-out electrode 5 to draw out the electron current from the electron source, and a drawing-out power source 6 to give a negative potential to the photoelectron screen 8. In this case, when the electrons have a high energy, the electron current impinges on the drawing-out electrode 5, and the resultant secondary electrons neutrize the accumulated charge on a substrate 2 which is irradiated by the ion flow 1. As a result, a heavy metal contamination of the wafer 2 is prevented, and the thermal radiation to the wafer 2 is reduced, to improve the device performance and the reliability.
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