Applying Raman spectroscopy, small-angle x-ray scattering, and atomic force microscopy it were studied phase composition and surface morphology of nanoscale films Si₃N₄ (obtained by RF magnetron sputtering

Abakumov, P. V.

Goncharov, I. Yu.

Piljuk, E. A.

Rodriguez, G. V.

Taran, S. V.

Zakhvalinskii, V. S.

English

DSpace at Belgorod State University

JOURNAL OF NANO- AND ELECTRONIC PHYSICS ЖУРНАЛ НАНО- ТА ЕЛЕКТРОННОЇ ФІЗИКИ Vol. 7 No 4, 04052(2pp) (2015) Том 7 № 4, 04052(2cc) (2015)   2077-6772/2015/7(4)04052(2) 04052-1  2015 Sumy State University Short Communication  Temperature Influence on the Properties of Thin Si3N4 Films  V.S. Zakhvalinskii1, P.V. Abakumov2, A.P. Kuzmenko2, A.S. Chekadanov2, E.A. Piljuk1, V.G. Rodriguez1, I.J. Goncharov1, S.V. Taran1  1 Belgorod National Research University, 85, Pobedy St., 308015 Belgorod, Russia  2 South-West State University, 94, 50 let Oktyabrya St., 305040 Kursk, Russia  (Received 28 September 2015; published online 10 December 2015)  Applying Raman spectroscopy, small-angle x-ray scattering, and atomic force microscopy it were stud-ied phase composition and surface morphology of nanoscale films Si3N4 (obtained by RF magnetron sput-tering).  Keywords: Raman spectroscopy, Small-angle x-ray scattering, Atomic force microscopy.   PACS numbers: 75.50.Ee, 75.78.Fg   1. INTRODUCTION  Si3N4 is one of the most widely used in microelec-tronics materials. One of possible application of silicon nitride is solar elements (SE). Usually the silicon ni-tride films are applied in SE and other microelectronic devices as passivation layers, that reduces the rate of surface recombination of charge carriers [1]. Another typical application of silicon nitride films is obtaining anti-reflection layer of SE [2]. Reduced production cost of solar cells can be achieved by simplification of the manufacturing technology and construction SE. It has been recently obtained uni-junction SE on the basis of Si3N4. Thin film of Si3N4 thickness 20 nm of hetero-structure solar cells Ag/n-Si3N4/p-Si (100)/Cu is forming a potential barrier and at the same time acting as a passivation layer and anti-reflector layer. The energy conversion coefficient (ECC) of the photovoltaic stric-ture was 6.4 % [3, 4]. One of possible ways to improve EEC is increasing of solar energy absorption due to developed relief and increasing the relative surface of the up-per layer of the heterostructure. The main purpose of this work was to investigate the influence of the substrate temperature of high-frequency magnetron sputtering films Si3N4 on the phase composition and the relative surface area of the film. Applying improved ВН-2000 magnetron sputtering unit it was installed an optical substrate sample heat-er, that allows to set the temperature during deposition in the range of 40 С up to 800 С. Non-reactive RF magnetron sputtering of films was carried out using solid-state target Si3N4. To analyze the changes in the distribution of par-ticles according to their size in magnetron films it was applied the method of small-angle x-ray scattering (SAXSees mc2, Anton Paar, Austria). The investiga-tions were conducted in the linear collimation mode, providing characterization of structural features of objects, ranging in size from 0.1 to 100 nm, with a resolution of up to 0.03 nm – 1, which is substantially higher than the best examples of spectral instru-ments. During analyzing of the distribution it was performed subtraction of the spectrum from conducted    Fig. 1 – The calculated volume functions DV(r) particle distri-bution according to their size r for coatings Si3N4 on sub-strates Si (100) at temperature TS  40 C, 500 C and 750 С  single-crystal silicon scattering with the same orien-tation. The obtained scattering curves were processed using the program GIFT (PCG Software Package). The calculated volume distribution function of particle size DV(r) for coating Si3N4 on the cold substrate and the silicon substrates at a temperature of 500 and 750 С are shown on Fig. 1. The analysis shows that a large part of the volume in silicon nitride Si3N4 film on the substrate at room temperature is occupied by parti-cles with a radius of about 2 and 7.5 nm. These data are consistent with earlier researches for magnetron coating on glass [5]. In films Si3N4 while heating the substrates, it was ob-served increasing minimum size of  occurring structural formations and the emergence of structures with different average static dimensions (for the sub-strate at 500 С – 5, 12, 20.5, 29 nm), аalso there is a significant increase in the maximum size of above 50 nm. To determine the changes in chemical structure was carried out Raman (Raman) scattering of light. Spec-tral data was obtained using a combination of Omega Scope, including a spectrometer SOLAR TII. Measure-ments were per-formed in configuration of "reflection»  r, nm  V.S. ZAKHVALINSKII, P.A. ABAKUMOV, ET AL. J. NANO- ELECTRON. PHYS. 7, 04052 (2015)   04052-2   Fig. 2 – Raman spectra of light scattering for the Si3N4 films, that were obtained by RF-magnetron sputtering on substrates at temperatures ТS  40, 300, 630, 750 С. The inset shows the wavelength range of 150-450 nm  (ZXXZ) applying a solid-state laser source is 532 nm (50 mW) with a diffraction grating 600 lines/mm. Spa-tial focusing of the probing radiation was about 500 nm, spectral resolution was 3 cm – 1. The intensity of the scattered radiation was sufficient for reliable study of all the characteristics in the spectrum of the magnetron coatings, which is illustrated in Fig. 2. Be-sides responsible for fluctuations lines atoms Si – 528 cm – 1 and its harmonics in the vicinity of  950 cm – 1 there are been detected vibrations at frequencies of 288, 307 and 347 cm – 1 that according to [6] correspond to fluctuations of a cubic silicon nitride. Most clearly they are driven in the Si3N4 obtained on a cold silicon substrate (40 С), while the films obtained by heating the substrates, their intensity increases, but this range is an amorphous halo. The study of electron diffraction was performed at room temperature on a Si3N4 thin foil using a transmission electron microscope of high reso-lution (2 Å) JEOL JEM-2100. The set interplanar dis-tances correspond to cubic Si3N4 [b], the nature of the diffraction rings indicates mixed (microcrystal-line and amorphous) state of Si3N4 film sputtered onto the sub-strate p-Si (100). Table 1 – Relative surface area of the films dependence of Si3N4 on substrate temperature  The substrate tem-perature, Celsius 40 С 300 С 500 С 800 С The relative surface area of the film,% 0.8 4.1 7.6 8.9  The study of thickness and surface morphology of films Si3N4 was conducted on an atomic force micro-scope NTEGRA Aura, NT-MDT in a controlled at-mosphere. The thickness of the film amounted to 20 nm. After processing the results of the study of sur-face morphology using a software package «Image Analysis P9» (NT-MDT) was found the dependence of the relative surface area of the Si3N4 film on the heat-ing temperature of the substrate during the rf-magnetron sputtering (Table 1). Thus, we have completed a study of nano-sized Si3N4 films, obtained by RF-magnetron sputtering at various temperatures of heating of substrate p-Si (100). Applying small-angle X-ray scattering method, Raman spectroscopy, electron transmission and atomic force microscopy, it was found that the film is a mixed phase consist of amorphous and cubic Si3N4, the average ra-dius of the particles increases from 2 nm to 7.5 nm at temperature increasing from 40 С to 750 С, and the relative surface area of the film increases from 0.8 % to 8.6 % when the temperature of the substrate varies from 40 С to 800 С. This work was financially supported by the Minis-try of Education and Science grant No 2014/420-367 and the Russian Foundation for Basic Research Project № 15-42-03192. The studies were carried out on the equipment center "Diagnostics structure and properties of nanomaterials", project № 14.594.21.0010, code RFMEFI59414X0010.   REFERENCES  1. J.L. Cruz-Campa, et al., Sol. Energ. Mater. Sol. C. 95, 551 (2011). 2. A. Lennie, H. Abdullah, S. Shaari, K. Sopian, Am. J. Appl. Sci. 6, 2043 (2009). 3. V.S. Zakhvalinskii, I.Yu. Goncharov, E.A. Kudryavtsev, E.A. Piluk, D.A. Kolesnikov, V.G. Rodriges, Z.A. Kabilov, S.V. Taran, A.P. Kuzmenko, J. Nanoelectron. Optoelectron. 9, 570 (2014). 4. V. Zakhvalinskii, E. Piliuk, I. Goncharov, V. Rodriges, A.V. Simashkevich, D.A. Sherban, L.I. Bruc, N. Curmei, M. Rusu, 29-th European Photovoltaic Solar Energy Con-ference and Exhibition, 851 (22-26 September, 2014: Am-sterdam, The Netherlands: 2014). 5. A.P. Kuzmenko, A.S. Chekadanov, S.V. Zakhvalinsky, E.A. Pilyuk, M.B. Dobromyslov, J. Nano- Electron. Phys. 5 No 4, 04025 (2013). 6. Andreas Zerr, et. аl., Nature 400, 340 (1999).  r, nm abr.u. 

Temperature influence on the properties of thin Si₃N₄ films

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Temperature influence on the properties of thin Si₃N₄ films

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