A study on the oxidation kinetics of silicon in inductively coupled oxygen plasma

The oxidation kinetics of silicon in inductively coupled oxygen plasma (ICP) was studied at temperatures ranging from 350 to 450 degrees C. The oxide growth kinetics was described by a linear-parabolic growth law, with a rapid initial growth and a negative linear-rate constant. Under oxygen pressure of 10 mTorr, the initial oxide growth at 350 degrees C (thickness below 25 nm) was faster than at 400 degrees C. An analysis of transverse-optical mode frequencies and etch rates indicated that the density of the surface oxide was lower than that of the bulk oxide. The oxidation kinetics was explained qualitatively by assuming that the ICP oxide consisted of a surface layer with a larger diffusion coefficient and a bulk layer with a smaller diffusion coefficient. On the other hand, the ICP oxidation of silicon with a thin chemical oxide showed a positive linear-rate constant and no surface layer effect, supporting the fact that the oxide grown by the ICP oxidation has a low-density surface layer with a larger diffusion coefficient. (C) 1999 American Institute of Physics. [S0021-8979(99)00119-X].