Si-oxide and Si-oxynitride interfaces analysed by ultra-low energy SIMS

Michał Ćwil 1,3Piotr Konarski 1Tomasz Bieniek 2Romuald Beck 2

1. Industrial Institute of Electronics (PIE), Dluga, Warszawa 00-241, Poland
2. Warsaw University of Technology, Institute of Microelectronics & Optoelectronics (imio), Koszykowa 75, Warszawa 00-662, Poland
3. Warsaw University of Technology, Faculty of Physics, Koszykowa 75, Warszawa 00-662, Poland

Abstract

Silicon oxides and oxynitrides are used for electronic application in wide scale. In the case of oxynitrides technology, the prime importance is to control the atomic concentration in thin SiOxNy layers. In the present paper we compare the depth profile analyses of oxides and oxynitrides using SIMS (Secondary Ion Mass Spectrometry) technique, which is ideally suited for nanostructure characterisation. A subnanometer depth resolution can be achieved with ultra-low energy (below 1 keV) ion beam due to atomic mixing reduction in sputtering process [1-2].

SiO2 on Si samples were formed by thermal heating (800-1100oC) of silicon wafers in oxygen flow. SiOxNy layers were obtained by nitrogen implantation followed by plasma oxidation process. The nitrogen plasma implantation was performed with NH3 and pure N2 plasma sources in 350oC. Influence of r.f. power, used during implantation on the oxynitride layer properties, was studied. The SiOxNy and SiO2 layers were 1, 2.5, 3.5, 4, 5 nm and 5, 15, 22, 50, 65, 85 nm thick respectively.

Ultra-low energy Ar+ ion beam (880 eV) was used in SAJW-05 SIMS analyser with quadrupole spectrometer. Quantitative atomic concentrations of N and O were calculated basing on Si2N+ and Si2O+ secondary ion currents according to Berkum [3]. Sputtering rate was calibrated basing on ellipsometry measurements. The obtained layers were also characterised by X-ray Photoelectron Spectroscopy.

Charge build-up effects during positive secondary ion detection were observed dependent of the SiO2 layer thickness. The SiOxNy/Si interface regions show differences related to the kind of plasma and the r.f. power of nitrogen implantation used.

[1] J.B. Clegg, et al.; Surf.Interf.Anal. 14 (1987) 307

[2] P. Konarski et al.; Appl.Surf.Sci. 203-204 (2003) 354

[3] J.G.M. Berkum et al.; Appl.Surf.Sci. 203-204 (2003) 414

 

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Presentation: oral at E-MRS Fall Meeting 2005, Symposium F, by Michał Ćwil
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-05-20 13:41
Revised:   2009-06-07 00:44