Observation of the Magnetic Separatrix Between a Magnetron and an Electron-Cyclotron Resonance Discharge

A circular planar magnetron sputtering source has been combined with an electron-cyclotron resonance (ECR) plasma source to reduce the operating voltage of the magnetron in order to avoid high-energetic particle bombardment of sensitive thin films during deposition. Although the ECR source produces a downstream plasma density of several 10¹⁰ cm^-3, the voltage reduction of the magnetron is limited to only a few percent. Using a geometry with the ECR source facing the magnetron target for maximum coupling, the shape of the discharge clearly shows a magnetic shielding of the magnetron against the ECR discharge limiting the electron injection into the magnetron torus.