Influence of substrate temperature and deposition rate on structure of thick sputtered Cu coatings

TLDR: Thor Thornton et al. as discussed by the authors used hollow and post-type cathode sputtering apparatuses at argon pressures of 1 and 30 mTorr to evaluate OFHC copper coatings on copper, tantalum, and stainless steel substrates.

Abstract: Thick [1–10 mil (25.4–254.0 μm)] OFHC copper coatings were deposited on copper, tantalum, and stainless‐steel substrates maintained at temperatures (T) in the 50 °–950 °C range, at rates of from 200 to 18 000 A/min, using primarily hollow and also post‐type cathode sputtering apparatuses at argon pressures of 1 and 30 mTorr. Coating structures were examined by preparing metallographic cross sections. Surface topographies and fracture cross sections were examined by scanning electron microscopy. Crystallographic orientations were determined by x‐ray diffraction. No significant deposition rate influence was found on the low‐temperature structure zones reported previously [J. A. Thornton, J. Vac. Sci. Technol. 11, 666 (1974)] or on the columnar nature of coatings formed at elevated T. Truly equiaxed grain structures were generally not observed with hollow cathodes. Annealing twins were found within the grains for T≳350 °C. Evidence of extensive recrystallization and grain growth was seen for T∠900 °C. Coatin...