Laser pulse induced microwave conductivity and spectroscopic ellipsometry characterization of helium and hydrogen plasma damage of the crystalline silicon surface

The decay of excess charge carriers, optically generated by an excimer laser pulse at the surface of monocrystalline silicon, has been determined by in-situ microwave reflection measurements. The influence of hydrogen and helium plasmas on the excess charge carrier kinetics has been determined. Both plasma treatments increase the decay rate and decrease the amplitude of the microwave reflection transients dramatically. Spectroscopic ellipsometry measurements performed during the plasma exposure have been fitted assuming the creation of a damaged surface layer. The thickness of this surface layer is increasing with increasing plasma exposure time. While for the helium plasma the creation of electronic defects is mainly an instant effect after plasma ignition, in the case of the hydrogen plasma exposure a continuously increasing number of recombination centers can be observed.