Naslov
Morphology and Structure of Sputtered W Thin Films

Autori
Milat, Ognjen ; Salamon, Krešimir ; Kovačević, Zorana ; Dubček, Pavo ; Jerčinović, Marko ; Radić, Nikola

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

Izvornik
19th International Vacuum Congress: Abstract book / - Pariz, 2013, 2565-2566

Skup
19th International Vacuum Congress

Mjesto i datum
Pariz, Francuska, 09.09.2013. - 13.09.2013

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Tungsten (W) thin films; structure; morphology; magnetron sputtering; GIXRD; XRR; GISAXS; X-ray

Sažetak
Crystal structure and morphology of tungsten (W) thin films, prepared by magnetron sputtering, were studied by grazing incidence x-ray diffraction and small angle x-ray scattering, x-ray reflectivity, and scanning electron microscopy with compositional analysis. Coexistence of two crystalline phases, α-W and β-W, and formation of amorphous phase (a-W) were observed for various Ar pressures (2-20 mTorr), and flow rates controlled by the applied power (10-90 watt)[1]. Depositions at low Ar pressures (< 5 mTorr) and high powers (> 40 watt) result in compact and smooth layers of crystalline α-W phase only. By reducing the sputtering power (20 watt), along with stable α-W, a metastable β-W phase occurs. For even lower power (10 watt), W film becomes amorphous and exhibits a columnar morphology, like in Fig.1, accompanied with a 25% reduced layer’s mass density compared to that of the bulk tungsten [2]. A similar columnar morphology was found also for films deposited at higher Ar pressures (> 5 mTorr), and moderate sputtering power of 20 watt ; the columns in high pressure films consist of β-W phase. The columns diameter in the amorphous phase was 3 nm, while for β-W phase the average columns size was 4-6 nm[2]. Columnar aggregations were revealed at wide scale of correlation lengths: up to 103 nm (Fig.1.). The highest mass density reduction, of up to 50%, was observed for highest pressure of 20 mTorr. Morphology of W films deposited at high Ar pressures was depth dependent with smaller columns (and inter-columnar voids) closer to the Si substrate. In the amorphous film one observed top surface layer of 3.5 nm which could be attributed to the oxygen rich W or WO3 phase. The appearance of β-W phase is related to the lowered flux of W atoms, increased film porosity, and correspondingly to the higher probability of oxygen incorporation. [1] N. Radić, A. Tone c , J. Ivkov, P. Dubček, S. Bernstorff, Z. Medunić Surf. Coat. Technol. 180 (2004) 66 [2] K. Salamon, O. Milat, N. Radić, P. Dubček, M. Jerčinović, accepted J.Phys D (Appl. Phys) 46 (2013)

Izvorni jezik
Engleski

Znanstvena područja
Fizika

POVEZANOST RADA