Reducing the self-sputtering threshold of a gasless (vacuum) magnetron in DC mode

We have explored the operation of a planar magnetron sputtering system operating in gasless (vacuum) DC mode and have found that the threshold value of discharge current can be reduced by a factor of 1.2–1.5 to achieve stable self-sputtering. This reduction of threshold current was achieved using three approaches – reducing the racetrack diameter while maintaining a constant linear current density (discharge current value per racetrack length, A/cm), increasing the discharge voltage by reducing the magnetic field, and adding material with higher sputtering yield to the magnetron sputtering target. • The threshold current of a stable self-sputtering DC gasless magnetron can be reduced by a factor of 1.2–1.5 by: reducing the racetrack diameter while maintaining a constant linear current density (discharge current value per racetrack length, A/cm), increasing the discharge voltage by reducing the magnetic field, and adding metals with higher sputtering yield to the magnetron sputtering target. • In vacuum mode with a copper target Cu²⁺ ions are observed (1–2%). There is also a weak current in the location of Cu³⁺ ions (less than 0.1 %). • For the gasless mode the I-V characteristic has a section with a negative slope (dI/dV < 0), that can be associated with the appearance of Cu2+ and even Cu3+ ions in plasma.