Multi‐instrument characterization of HiPIMS and DC magnetron sputtered tungsten and copper films

• Published in: Surface and interface analysis Vol. 52; no. 7; pp. 433 - 441
• Main Authors: Roychowdhury, Tuhin, Shah, Dhruv, Jain, Varun, Patel, Dhananjay I., Dodson, Berg, Skinner, William, Hilfiker, James N., Smith, Stacey J., Linford, Matthew R.
• Format: Journal Article
• Language: English
• Published: Bognor Regis Wiley Subscription Services, Inc 01.07.2020
• Subjects: Atomic force microscopy; atomic force microscopy (AFM); Copper; copper (Cu); Crystallites; Direct current; direct current magnetron sputtering (DCMS); energy dispersive X‐ray spectroscopy (EDX); Grain size; high‐power impulse magnetron sputtering (HiPIMS); Magnetron sputtering; Metal films; Microscopes; Photoelectrons; Refractivity; Scanning electron microscopy; scanning electron microscopy (SEM); Silicon wafers; Spectroellipsometry; spectroscopic ellipsometry (SE); Spectrum analysis; Sputtered films; Tungsten; tungsten (W); X ray photoelectron spectroscopy; X‐ray diffraction (XRD); X‐ray photoelectron spectroscopy (XPS)
• ISSN: 0142-2421; 1096-9918
• DOI: 10.1002/sia.6753

In this work, copper and tungsten were sputtered onto silicon wafers by direct current magnetron sputtering (DCMS) and high‐power impulse magnetron sputtering (HiPIMS). The resulting films were characterized by energy dispersive X‐ray spectroscopy (EDX), X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and X‐ray diffraction (XRD). By EDX and XPS, all the sputtered films showed only the expected metal peaks. By XPS, the surfaces sputtered by DCMS were richer in oxygen than those produced by HiPIMS. By AFM, the surfaces were quite smooth. The root mean square (RMS) roughness values are as follows: 0.83 nm (W, HiPIMS), 1.10 nm (W, DCMS), 0.85 nm (Cu, HiPIMS), and 1.78 nm (Cu, DCMS). By SEM, the HiPIMS films exhibited smaller grain sizes, which was confirmed by XRD. The crystallite sizes estimated by XRD are as follows: 4 nm (W, body‐centered cubic, HiPIMS), 13 nm (W, body‐centered cubic, DCMS), 7 nm (W, cubic, HiPIMS), 14 nm (W, cubic, DCMS), 25 nm (Cu, HiPIMS), and 35 nm (Cu, DCMS). By SE, the HiPIMS surfaces showed higher refractive indices, which suggested that they were denser and less oxidized than the DCMS surfaces.