Electronic states created in p-Si subjected to plasma etching: The role of inherent impurities, point defects, and hydrogen

Reactive ion etching and magnetically enhanced reactive ion etching with CHF3/O2 are employed to remove SiO2 from boron-doped Si substrates. Etch-induced gap states in the substrate are monitored using deep-level transient spectroscopy. The dominant state is found to be a donor with a hole binding energy of 0.36 eV. The state has been identified as that of the carbon-interstitial oxygen-interstitial pair. The depth profile of the pair is determined by two competing mechanisms: the pair generation and its electrical deactivation by atomic hydrogen. The latter process is especially prevalent in the presence of a magnetic field.