Mechanical Properties of Zr–Si–N Films Fabricated through HiPIMS/RFMS Co-Sputtering

Abstract

Zr-Si-N films were fabricated through the co-deposition of high-power impulse magnetron sputtering (HiPIMS) and radio-frequency magnetron sputtering (RFMS). The mechanical properties of the films fabricated using various nitrogen flow rates and radio-frequency powers were investigated. The HiPIMS/RFMS co-sputtered Zr-Si-N films were under-stoichiometric. These films with Si content of less than 9 at.%, and N content of less than 43 at.% displayed a face-centered cubic structure. The films' hardness and Young's modulus exhibited an evident relationship to their compressive residual stresses. The films with 2-6 at.% Si exhibited high hardness of 33-34 GPa and high Young's moduli of 346-373 GPa, which was accompanied with compressive residual stresses from −4.4 to −5.0 GPa.

Effect of Bias Voltage on Mechanical Properties of HiPIMS/RFMS Cosputtered Zr–Si–N Films

“…The films prepared at bias voltages of −100 V and −150 V were Zr 62.3 Si 0.4 N 37.3 and Zr 62.2 Si 0.4 N 37.4 , respectively, which exhibited a constant and Si-less level attributed to severe ion bombardment. In our previous study on HiPIMS-RFMS-prepared Zr–Si–N films fabricated using the same gas flow (Ar: 28 sccm, N 2 : 2 sccm) at ground state [19], the Si content increased from 0 to 10 atom % accompanied with an increase in N content from 29 to 40 atom %, which was attributed to the high affinity of Si and N [11,20]. Moreover, the Si content of the samples in batches B and C exhibited decreasing tendencies with an increase in substrate bias voltage, whereas the variation in N content was not correlated with the substrate bias voltage.…”

“…Figure 2a, Figure 3a, and Figure 4a illustrate the grazing incidence XRD (GIXRD) patterns of the films in batches A, B, and C, respectively, which display a face-centered cubic (fcc) ZrN [ICDD 00-035-0753] phase. In our previous study [19], the HiPIMS-RFMS-fabricated Zr–Si–N films with Si content less than 7.6 atom % were crystalline, whereas Zr–Si–N films with Si content more than 10 atom % had a dominant X-ray amorphous phase. Figure 2b illustrates the XRD patterns of the Zr–Si–N films in batch A obtained through Bragg–Brentano scan.…”

“…Tang et al [20] fabricated Zr–Si–N films through a hybrid system comprising a superimposed HiPIMS-medium frequency and RF sputtering at a 200 °C substrate temperature and −100 V bias voltage; their results exhibited that the films containing 4.7 atom % Si had the highest hardness (33.4 GPa). Moreover, in our previous study [19], the hardness and Young’s modulus of the HiPIMS-RFMS cosputtered Zr–Si–N films exhibited linear relationships to their compressive residual stresses ranging from −0.2 to −5.0 GPa. Therefore, it is crucial to explore increasing the mechanical properties of Zr–Si–N films, and hence, its compressive residual stress was increased through application of a negative bias voltage on the substrates during deposition.…”

“…The HiPIMS-RFMS cosputtering system was illustrated in detail in a previous study [19]. The Ti and Zr targets with a diameter of 76.2 mm were connected to a pulse power supply (SPIK 2000A, Shen Chang Electric, Taipei, Taiwan), whereas the Si target with a diameter of 50.8 mm was connected to a radio-frequency power generator of 13.56 MHz.…”

“…Moreover, hybrid processes such as direct-current magnetron sputtering (HiPIMS-DCMS) [17] and radio-frequency magnetron sputtering (HiPIMS-RFMS) [18] were used to increase the deposition rate, which was a limitation of the conventional HiPIMS process [13,14]. In a previous study [19], the crystalline Zr–Si–N films of 2–6 atom % Si prepared using a HiPIMS-RFMS process showed low surface roughness (0.8–1.4 nm) and high nanoindentation hardness (33.1–34.3 GPa), Young’s modulus (346–373 GPa), and compressive residual stress (4.4–5.0 GPa). Tang et al [20] fabricated Zr–Si–N films through a hybrid system comprising a superimposed HiPIMS-medium frequency and RF sputtering at a 200 °C substrate temperature and −100 V bias voltage; their results exhibited that the films containing 4.7 atom % Si had the highest hardness (33.4 GPa).…”