Pulsed gas plasma doping method and apparatus

For example, a method and apparatus for doping a dopant such as phosphine or arsine to the surface of the substrate. The doping is essentially inert gas - is performed by the plasma composed of - for example helium or argon. Wherein said dopant is a low concentration. By subjecting the conformal doping, preferably for producing a monolayer of the dopant, the gas stream introduction position is switched during the doping process. The gas mixture essentially during the first period is introduced through the top center port in said process chamber, subsequently the gas mixture essentially in, during a second period around or end injection port It is introduced through the. The switching is continued so as to alternately as a plasma process.