Ultrafast UV-laser-induced oxidation of silicon: Control and characterization of the Si-SiO2 interface

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Abstract
A new low‐temperature method of rapidly forming (>100 Å/sec) high‐quality patterned silicon dioxide (SiO2) layers up to a thickness of 1 μm on silicon substrates is presented. Ultraviolet pulsed laser excitation in an oxygen environment is utilized. Infrared absorption spectroscopy, capacitance‐voltage measurements, and soft x‐ray photoemission are employed to characterize the oxide films and the Si‐SiO2 interface. No shift, but a significant broadening of the Si‐O stretching mode compared with thermally grown oxides is found, indicating that the laser‐grown oxide is stoichiometric but with a higher degree of disorder. Similar results are obtained from soft x‐ray photoemission data: the bulk of the laser‐grown SiO2 shows no sign of SiOx suboxides, while at the interface a layer of SiOx is found of comparable thickness as in thermally grown SiO2. From capacitance‐voltage measurements we deduce a fixed oxide charge near the Si‐SiO2 interface of 6×1010/cm2 for oxides that have been thermally annealed following the laser‐induced growth making this material a candidate for applications in semiconductor devices.

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