Model for nitridation of nanoscale SiO{sub 2} thin films in pulsed inductively coupled N{sub 2} plasma

Journal Article · Fri Jul 15 04:00:00 EDT 2005 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.1949272· OSTI ID:20713995

Rauf, Shahid; Lim, Sangwoo; Ventzek, Peter L.G. ^[1]

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1. Freescale Semiconductor, Inc., 3501 Ed Bluestein Boulevard, MD K-10, Austin, Texas 78721 (United States)

As nitration of SiO{sub 2} gate dielectric can increase the film's dielectric constant and reduce boron penetration into the Si channel during ion implantation, plasma nitridation is of considerable interest for the fabrication of semiconductor devices. A coupled plasma equipment-surface physics model is used in conjunction with an experimental analysis of nitrided SiO{sub 2} thin films to understand the mechanism of SiO{sub 2} plasma nitridation. This investigation is conducted in a pulsed inductively coupled N{sub 2} plasma. Computational results show that N atoms and N{sub 2}{sup +} ions are the primary species in the N{sub 2} plasma that contribute to the nitridation of SiO{sub 2} thin film. N atoms adsorb at the SiO{sub 2} surface and diffuse into the bulk film, and most nitrogen near the surface is due to these adsorbed N atoms. N{sub 2}{sup +} ions, on the other hand, penetrate deeper into the SiO{sub 2} film in an ion-implantation-like manner, and these ions are responsible for the observed tail in the nitrogen concentration profile. Nitrogen concentration in the film can be increased by enhancing the plasma source power or the nitridation time. However, once the dielectric surface starts saturating with nitrogen, further nitrogen adsorption is inhibited and nitridation rate tapers off. As the fluxes of atomic N and N{sub 2}{sup +} ions to the wafer decrease with increasing gas pressure, the nitridation rate decreases with gas pressure. For the range of SiO{sub 2} film thickness examined (13-15 A ), the nitrogen transport and reaction properties in the film are film thickness dependent, probably due to the nonuniform density of the initial SiO{sub 2} thin film or to interfacial stresses.

• OSTI ID: 20713995
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 2 Vol. 98; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ADSORPTION
BORON
DIELECTRIC MATERIALS
FABRICATION
ION IMPLANTATION
NANOSTRUCTURES
NITRATION
NITRIDATION
NITROGEN
NITROGEN IONS
PERMITTIVITY
PLASMA
SEMICONDUCTOR DEVICES
SILICON OXIDES
THIN FILMS