Patent ID: 8101246

Claim:
A method of treating a surface of a substrate in a plasma enhanced process, the substrate having a surface to be treated and a further surface not to be treated and located opposite the surface to be treated, the method comprising the steps of: providing a space between a flat face of a magnetron electrode on a first side and a surface of a substrate support facing the electrode on a second, opposite side, wherein the magnetron electrode is of an unbalanced type and comprises a flat magnetron face with peripheral and central magnetic poles of opposite polarities, and an electrode piece being powered with a high frequency alternating voltage, and wherein the substrate support is electrically grounded, electrically floating or negatively biased, positioning the substrate in said space with the further surface lying against the substrate support and the surface to be treated facing towards the face of the magnetron electrode, evacuating said space and feeding a process gas or process gas mixture into said space, keeping it at a reduced pressure and therewith igniting and sustaining a plasma in said space, wherein a magnetic field generated by the magnetron electrode causes darker tunnels to extend along the magnetron face wherein the tunnels have a height perpendicular to the face of the magnetron electrode, adapting the distance between the surface to be treated and the face of the magnetron electrode to the magnetic field such that there is a visible plasma band running between darker tunnels and the surface to be treated, and such that said surface, for the duration of treatment, is situated outside of the darker tunnels in the plasma band, and wherein a distance between the surface being treated and the face of the magnetron electrode is at least 2% larger than a visible height of the darker tunnels.