Diffusion of implanted nitrogen in silicon

Growth of thinner gate oxides and their thickness control is one of many challenges in scaling technologies today. Nitrogen implantation can be used to control gate oxide thicknesses. This article reports a study on the fundamental 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 Angstrom screen oxide into Czochralski silicon wafers. Furnace anneals at a range of temperatures from 650 to 1050 degrees C have revealed anomalous diffusion behavior. For the 40 keV implants, nitrogen diffuses very rapidly and segregates at the silicon/silicon-oxide interface. Qualitative modeling of this behavior is also discussed in terms of the time taken to create a mobile nitrogen interstitial through the kickout, Frenkel pair, and the dissociative mechanisms. (C) 2000 American Institute of Physics. [S0021-8979(00)09205-7].