Structural and electrical characteristics of W–N thin films prepared by reactive rf sputtering

Abstract

Articles you may be interested inStructural and electrical characteristics of high quality (100) orientated-Zn 3 N 2 thin films grown by radiofrequency magnetron sputtering Epitaxial Ti 1-x W x N alloys grown on MgO(001) by ultrahigh vacuum reactive magnetron sputtering: Electronic properties and long-range cation orderingThe crystal structure, chemical bonding state, composition, and electrical resistivity of W-N films deposited by reactive rf sputtering are investigated by x-ray diffraction, x-ray photoelectron spectroscopy, Auger electron spectroscopy, Rutherford backscattering spectrometry, and four-point probe. Using 150 W of sputtering power and 25% of N 2 partial flow rate, the deposition rate and resistivity of W-N films decrease with increasing negative substrate bias. When the substrate bias is set at Ϫ100 V, resistivity of W-N films increases while the deposition rate decreases with increasing N 2 partial flow rate. WϩW 2 N mix phase, W 2 N phase, and W 2 NϩWN mix phase are obtained at 10%, 15%-25%, and 40% of N 2 partial flow rate, respectively. When the N 2 partial flow rate is greater than 40%, the films become amorphous like. Nitrogen concentration in the W-N films increases continuously with increasing N 2 partial flow rate, and the W 4 f core-level electrons change gradually from metallic W bondings to WN bondings. By reducing the sputtering power to 50 W, we have found that film resistivity also rises with increasing N 2 partial flow rate but crystalline W 2 N phase can be obtained with 10%-50% of N 2 partial flow rate. The connection between the process conditions, structural change and electrical resistivity of the sputtered W-N thin films is discussed.

Cubic β-WN layers: Growth and properties vs N-to-W ratio

“…5(a μΩ-cm for T s = 700 °C. That is, the WN x layers in this study exhibit a range of resistivities from 1.1-4.5 ×10 -5 Ω-m, which is within the range of previously reported values for WN x of 0.1-5.0×10 -5 Ω-m [26,37,41,[64][65][66], while other reports on WN x layers including samples obtained by MOCVD or sputtering at high working gas pressures or high ion bombardment energies indicate even higher resistivities ranging from 10 -4 -10 -1 Ω-m [33,38,39,44,67,68], which is likely due to their lower crystalline quality. The layers grown at T s = 800 °C, which, as discussed above, consist primarily of BCC-W grains and have a low nitrogen concentration corresponding to x = 0.06, 0.06, and 0.04, respectively, have resistivities of 50±2, 42±1, and 48±2 μΩ-cm.…”

“…The composition of tungsten nitride layers is affected by deposition parameters and method, which include reactive DC magnetron sputtering [26][27][28]30,[32][33][34][35][36][37], reactive pulsed laser deposition [34,38,39], RF sputtering [40][41][42], cathodic arc deposition [43], atomic layer deposition [44], and chemical vapor deposition [29,[45][46][47]. DC reactive magnetron sputtering in a Ar+N 2 mixture has been reported to yield x = 0.33 with a N 2 fraction in the gas of f N2 = 10% [30], or x = 0-0.5 with f N2 increasing from 0-75% [36], but also x = 0-1.1 for f N2 = 0-75% [32], x = 0-1.2 for f N2 = 0-63% [28], and x = ~0-1.2 for f N2 = 5% with an increasing 17-26 Pa total pressure [37].…”

“…However, the layers with high N content x > 0.9 have a tendency to exhibit a hexagonal WN phase [28,40]. RF sputter deposition yields in many cases even higher nitrogen 4 concentrations (again exhibiting a hexagonal phase for high x), likely due to energetic implantation, with x = 0.6-1.6 for f N2 = 10-75% [41], x = 1.1-1.4 for f N2 = 10-60% [42], x = 0.11-0.25 for P N2 = 0-1.6 Pa with a constant 0.53 Pa Ar [34], and x = 0.35-1.17 for f N2 = 38-83% [40].…”

Impact of Ar Flow Rates on Micro-Structural Properties of WS2 Thin Film by RF Magnetron Sputtering

“…As Ar facilitates to achieve plasma from the source material without taking part in any reaction, it is commonly used for sputtering. Moreover, the gas flow rate has a significant influence on film stoichiometry, phase composition, and preferred orientation as well [ 28 , 29 , 30 , 31 , 32 ]. It is also reported that argon-nitrogen gas mixtures influence the structural properties of the film and improve the adhesivity [ 33 ].…”

Effects of the Nitrogen Flow Ratio and Substrate Bias on the Mechanical Properties of W–N and W–Si–N Films

“…W-N films were developed as hard coatings and display remarkable mechanical properties [1][2][3][4][5][6][7]. The phase of W-N films varies from α-W to β-W, β-W 2 N, and δ-WN as the N concentration increases [8,9]. The β-W 2 N phase is a B1 structure, in which N atoms occupy half of the octahedral interstitial sites of cubic close-packed W atoms [9][10][11].…”