Naslov
Disordered tungsten-carbon alloys produced by reactive magnetron sputtering

Autori
Radić, Nikola ; Tonejc, Antun ; Jakšić, Milko ; Pastuović, Željko

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Extended Abstracts of JVC-7 / Bohatka, Sandor - Deberecen : Lorand Eotvos Physical Society, 1997, 73-74

Skup
7th Joint Vacuum Conference of Hungary, Austria, Croatia and Slovenia

Mjesto i datum
Debrecen, Mađarska, 26.05.1997. - 29.05.1997

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
.

Sažetak
The excessive amount of carbon-supplying admixture in reactive sputtering gas results in a formation of strongly disordered/ amorphous tungsten-carbon alloys(1,2). The unbound carbon, hydrogen and/or hydocarbon fragments incorporated in the tungsten-carbon film during growth might cause such amorphization. We investigated the effects of benzene partial pressure, substrate temperature and substrate bias voltage upon the structure of tungsten-carbon films produced by reactive sputtering. Tungsten-carbon thin films were deposited onto glass or monocrystalline silicon substrates by reactive sputtering in a two-source device described in details previously(3). The magnetron discharges operated in argon+benzene gas mixture at 2 Pa total pressure. The current density was 6 mA/cmý in both magnetrons, while discharge voltage increased with the C6H6 partial pressure and varied in the 330-450 V range. Deposition rate was 0.2-0.3 nm/s and the final film thickness was about 1 ćm. The benzene partial pressure was 1.25%, 2.5% or 5% of total pressure, respectively. The substrate temperature was varied in steps of 200řC, while substrate potential was floating or biased -70 V with respect to discharge plasma. The carbon concentration in the prepared films was measured by RBS analysis. As expected, the increase in benzene partial pressure in working gas results in a higher carbon content in the deposited film. However, no simple proportionality is established: while for both 1.25% and 2.5% C6H6 partial pressures the carbon to tungsten ratio in the deposited films is between 0.5 and 0.75, in the case of 5% C6H6 it considerably exceeds 1. The effects of substrate temperature and bias voltage on total carbon content are pronounced only in films deposited with 5% C6H6 partial pressure. The film structure was determined by X-ray diffraction (XRD) method. The XRD patterns obtained for W-C films deposited with 1.25% C6H6 partial pressure are given in Fig.1, together with the XRD patterns of some substances expected to be found in the films. As seen, the films deposited at room temperature (a,d) exhibit structure resembling a strongly disordered W2C or WC1-x carbides, while WC1-x microcrystalline structure with very small grains is formed on substrates held at 400řC during deposition (c,f). The effects of substrate bias (-70 V on samples presented on right panel) are noticeable only in case of depositions onto substrates at room temperature. In the cases of 2.5% and 5% C6H6 partial pressure, the films with disordered WC1-x structure are generally formed. However, a strong increase of the (200) reflection intensity with respect to the (111) reflection intensity is observed with the increase in substrate temperature, indicating change in film texture with deposition temperature. The study has demonstrated that the W-C films can be prepared by reactive magnetron sputtering using benzene C6H6 as a carbon percusor. The film structure is strongly disordered, presumably due to the incorporation of the unbound carbon.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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