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Unformatted text preview: Ultrathin silicon oxynitride film formation by plasma immersion nitrogen implantation I. J. R. Baumvol, a) C. Krug, and F. C. Stedile Instituto de Fı´sica-Instituto de Quı´mica, UFRGS, Porto Alegre, Rio Grande do Sul 91509-900, Brazil M. L. Green, D. C. Jacobson, and D. Eaglesham Bell Laboratories-Lucent Technologies, Murray Hill, New Jersey 07974 J. D. Bernstein, J. Shao, A. S. Denholm, and P. L. Kellerman Eaton Corporation, Implant Systems Division, Beverly, Massachussets 01915 ~ Received 25 September 1998; accepted for publication 1 December 1998 ! A method is proposed to prepare ultrathin silicon oxynitride films for gate dielectrics used in deep submicron metal–oxide–semiconductor field effect transistor device structures, namely plasma immersion N implantation into SiO 2 films. Plasma immersion implantation pulse voltages in the range 200–1000 V, and fluences from 10 16 to 10 17 N cm 2 2 were implanted into thermally grown SiO 2 films, with thicknesses between 3 and 6 nm. The areal densities of N and O in the resulting oxynitride films were determined by nuclear reaction analysis, before and after annealing in high-vacuum. N, O, and Si profiles in the films were determined with subnanometric depth resolution by medium energy ion scattering. The results indicate that plasma immersion ion implantation allows for shallow and controlled deposition of significant amounts of nitrogen ~ up to 3.8 nm of equivalent Si 3 N 4 thickness ! . Implantation is accompanied by moderate damage at the oxynitride/Si interface which can be recovered by thermal annealing. © 1999 American Institute of Physics. @ S0003-6951 ~ 99 ! 01706-4 # Increasing attention has been devoted to ultrathin silicon oxynitride films for use as gate dielectrics in subquarter- micron metal–oxide–semiconductor field effect ~ MOSFET ! devices, from the viewpoint of performance and reliability. 1,2 Ion implantation of nitrogen at low energies ~ between 10 and 1000 eV ! is now being considered as an attractive, low tem- perature, and controllable route to form these materials, as compared to typical high thermal budget growths in N 2 O or NO. 3–7 Further, ion implantation can result in oxynitrides with higher N concentration than the aforementioned thermal processes. We report here on studies of plasma immersion ion im- plantation ~ PIII ! of N 8,9 into bare Si, or ultrathin SiO 2 films ~ preoxides ! . The pulse voltage in the plasma immersion ap- paratus was varied between 200 and 1000 V. According to the projected ranges and straggling obtained from Monte Carlo simulations using the TRIM program 10 given in Table I, in this energy range a substantial amount of the implanted N atoms should remain within the oxide films. The implanta- tion fluences were between 10 16 and 10 17 N cm 2 2 . The areal densities of N and O in the films were determined by nuclear reaction analysis ~ NRA ! using, respectively, the 14 N( d , a ) 13 C reaction at 1.45 MeV, and the 16 O( d , p ) 17...
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This note was uploaded on 12/10/2009 for the course IF PFIS1200 taught by Professor Antonio during the Spring '09 term at Universidade Federal do Rio de Janeiro.
- Spring '09