Effects of high carbon concentration upon oxygen precipitation and related phenomena in CzSi

Publisher Website
Google Scholar
Abstract
Effects of high carbon concentration upon oxygen precipitation and related phenomena in Czochralski (Cz) silicon have been investigated by combining various furnace and rapid thermal anneals. Our data show that oxide precipitate (OP) density, estimated from changes in interstitial oxygen concentration (ΔOi), increases with increasing substitutional carbon concentration, Cs, while thermal donor (TD) formation is inhibited at high Cs. Even though ΔOi increases monotonically with Cs, synchrotron radiation section topographs of processed high carbon content wafers (Cs∼4 ppma) exhibit Pendellösung fringes, indicating a strain‐free bulk state. Our transmission electron microscope and optical microscopic data also show very few resolvable structural defects associated with precipitates inside the bulk Si. Using a thermodynamic and kinetic model, we attempt to explain: (1) reduced thermal donor formation, (2) lack of bulk stress notwithstanding high ΔOi, and (3) predominantly polyhedral precipitate morphologies in high carbon content CzSi.