Performance of inductively coupled plasma assisted sputtering with internal coil for ferromagnetic CoCrTa film deposition

The performance of inductively coupled plasma (ICP)-assisted sputtering with an internal coil was revealed for deposition of ferromagnetic Co-based alloy films. Three types of internal coil, a directly grounded bare coil, a capacitively coupled bare coil and an insulated coil, were investigated with regard to the crystalline structure of films and plasma characteristics. Highly c-axis textured hexagonal-close-packed (hcp) film growth was achieved in the bare coil system at a medium operating Ar pressure of 1.3 Pa. Pole figure measurements showed that the film grown on a low-temperature Si substrate contained small face-centered-cubic phase in the c-axis textured hcp crystal. Plasma diagnostics suggested that high plasma space potential beyond 80 V caused highly textured growth through the effect of ion bombardment with proper energies for crystallization. The superior capability of ICP-assisted sputtering with a capacitively coupled bare coil was revealed for textured growth in the thin layer on a substrate surface. A high deposition rate was achieved as a result of high electron density of the order of 1011 cm-3 in ICP-assisted sputtering with an insulated coil. However, the insulated coil system could not achieve textured growth