Characterization of Si etching with N-fluoropyridinium salt

The etching mechanism of Si by N-fluoropyridinium salt has been discussed. The etching rate increases with light intensity or temperature. Si is etched by the irradiation of light with an energy higher than the band gap of Si. The etching rate is almost independent of the carrier type or the dopant concentration. The back bond of Si weakens by exciting electrons in the back bond. The N–F bond in the salts is broken by receiving excited electrons and releases an active F species. The F species react with Si to produce SiF4 because of the weakened back bond. The SiF4 is released.

► We propose an etching model of Si with N-fluoropyridinium salt.
► N-fluoropyridinium salt releases active F species by receiving excited electrons from Si.
► The etching rate is independent from the carrier type or dopant concentration.
► The etching rate increases with light intensity or temperature.
► The photo-etching needs a photon energy higher than the band gap of Si.