Plasma-enhanced photoemission detection: a new method for real-time surface monitoring during plasma processing

A technique for characterization of semiconductor surfaces during plasma exposure, plasma-enhanced photoemission (PEP) detection, which is compatible with plasma process conditions and is sensitive to surface electric properties, is described. Technique parameters of RF power, laser power, and laser synchronization with the RF cycle are characterized. The PEP technique is used in real time to study the effects of plasma processing on the electronic properties of doped silicon surfaces. During exposure to sputtering or reactive etching plasma, significant differences are noted between n- and p-type Si and between the use of low and high laser power. Results are interpreted using a band-bending model and the influence of surface or defect states induced by ion bombardment during process exposure.