Electrical characterization of carrier trapping behavior of defects created by plasma exposures

Abstract

Defect creation in Si substrates during plasma exposure was investigated by means of a capacitance–voltage technique employing various modulation frequencies. We focused on the frequency-dependent capacitance near the flat-band voltage of the damaged structures on its depletion/inversion side. The proposed technique provides the density of defects (ndam) and characteristic damaged layer thickness (λdam) for various modulation frequencies. We characterized carrier capture and emission processes governed by the created defects—responsible for the key performances of electronic devices such as noise behavior—from the obtained frequency-dependent ndam. In the case of Ar plasma exposure, ndam was shown to increase as the average energy of impinging ions increases. The trap time constants for the defects to capture and emit carriers were found to be on the order of 10−7 s. The proposed technique provides the detailed carrier trapping feature of defects which is indispensable for future plasma process and electronic device designs.