Diffusion of implanted nitrogen in silicon

Growth of thinner gate oxides and their thickness control is one of many ch allenges in scaling technologies today. Nitrogen implantation can be used t o control gate oxide thicknesses. This article reports a study on the funda mental behavior of nitrogen diffusion in silicon. Nitrogen was implanted as N-2(+) at a dose of 5 x 10(13) ions/cm(2) at 40 and 200 keV through a 50 A ngstrom screen oxide into Czochralski silicon wafers. Furnace anneals at a range of temperatures from 650 to 1050 degrees C have revealed anomalous di ffusion behavior. For the 40 keV implants, nitrogen diffuses very rapidly a nd segregates at the silicon/silicon-oxide interface. Qualitative modeling of this behavior is also discussed in terms of the time taken to create a m obile nitrogen interstitial through the kickout, Frenkel pair, and the diss ociative mechanisms. (C) 2000 American Institute of Physics. [S0021-8979(00 )09205-7].