109-dimitrijev-apl-1539-1993 - M odel for dielectric S...

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Model for dielectric growth on silicon in a nitrous oxide environment Sima Dimitrijev, Denis Sweatman, and H. Barry Harrison School of Microelectronic Engineering, G@ith University, Nathan, Brisbane, Queensland, Australia, 411 I (Received 4 September 1992; accepted for publication 4 January 1993) In this letter, a model for growth kinetics of ultrathin dielectrics obtained by oxidation of silicon in a nitrous oxide environment is proposed. The model assumes that the oxide growth is limited by time-dependent interface reaction, which is slowed down and eventually completely blocked as oxide growth sites are neutralized by nitrogen atoms. The model fits experimental data extremely well, both with time and temperature. The need for ultrathin dielectrics ( < 15 nm) on silicon for future generation integrated circuits is firmly estab- lished. ’ Various techniques have been used to form these dielectrics, however, perhaps the most promising are those produced in a nitrous oxide (N,O) environment. These dielectrics have several desirable properties including tem- perature dependent self-limiting thickness, and lower sus- ceptibility to hot carrier stressing compared to other tech- niques. 2A The growth kinetics of these films, in particular the self limiting thickness as a function of temperature is of interest when working with such thin layers. In this letter we propose a model for the growth kinetics for this form of dielectric formation. The experimental conditions were reported by Ting et al. ’ and are briefly expanded upon here. Lightly doped silicon wafers (boron) of (100) orientation and resistivity e-5 Q cm were used. The wafers were given a standard RCA clean and a dip in dilute HF before a final rinse in de-ionized water prior to growth in a commercial rapid thermal processing unit for various times and temperatures in a high purity N20 Temperatures were taken in 50 “C intervals from 950 “C through to 1200 “C for times from 10 to 300 s. Oxide thicknesses were measured with an ellipsometer using a refractive index of 1.462.* The results obtained are shown in Fig. 1 [symbols) and are characterized by a rapid initial growth and finally a plateau in the dielectric growth. We performed similar experiments to confirm this
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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.

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109-dimitrijev-apl-1539-1993 - M odel for dielectric S...

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