X-ray imaging during plasma-source ion implantation

Plasma sour ce ion implantation (PSII) is a technique for modifying surfaces that places the object to be modified directly into a plasma and then negatively pulse biases the object so as to implant positive ions. If the voltage is high enough, Xrays can be generated by electrons that are also accelerated by the pulse. This work describes techniques for imaging and characterizing the X-rays. A pinhole camera teas used to image the X-rays being emitted as electrons collided with surfaces in the chamber. The images show that X-rays are generated at the chamber walls and near the target. The time dependence of these X-rays during each pulse was examined using a PIN diode X-ray detector. Then, using another X-ray sensor and pulse-height analyzer, the spectra of the emitted X-rays was determined. The object is to relate the X-ray intensity and spectrum to the temporal and spatial values of the implantation dose so that it may be used as a process monitor and a control sensor.