In this work, porous copper thin films were prepared by magnetron sputtering (MS) deposition using helium as the process gas. Electron microscopy techniques were used to study the shape, size, amount and distribution of the pores. Working under direct current (DC) or radiofrequency (RF) conditions, enabled to achieve respectively a dense porous or an open porous columnar microstructure. At the nanoscopic level a characteristic solid-gas nanocomposite structure was also produced in both films. Spherical and faceted nano-bubbles filled with helium, with a size range of 1-22 nm and a uniform distribution across the entire thickness were visualized. RF conditions allowed higher gas loading, achieving up to 6.2 at.% He preferentially occluded in smaller pores. Characterization revealed that the RF-deposited copper (Cu) film is oxidised to a greater depth than the DC-deposited film, forming a thicker copper oxide(s) layer. This phenomenon can be attributed to the open porous nanostructure of the former. The results presented herein improve our understanding of MS deposition of copper with helium as process gas and pave the way for designing a wide range of materials with applications in the field of fusion reactors, (electro)catalysis, photocatalysis, fuel cells, electronics and the fabrication of negative crystals.