Substrate Temperature Reduction During Rotatable Magnetron Sputter Deposition by the use of Magnetically Guided Anodes

Substrate Temperature Reduction During Rotatable Magnetron Sputter Deposition by the use of Magnetically Guided Anodes

Dermot Monaghan
Gencoa Ltd

Sputter deposition from planar magnetron geometries tend to produce lower substrate heating when compared to a rotatable magnetron. Planar magnetrons benefit from a dark space shield that surrounds the cathode and will collect electrons as the electrons loose energy and spiral away from the target under the influence of the magnetic field trap. A rotatable magnetron avoids the use of a dark space shield and this has the advantage of a cleaner environment in the target area as there is no coating build-up on parts near the target. But one major downside is that there is no active way to collect electrons so they contribute to higher substrate heating. One method to avoid this problem is to use a magnetic channelling of the electrons away from the substrate and into a cooled ‘anode’ type receiver. This can be achieved by combining the rotatable magnetrons magnetic field trap, with a magnetic field linking into such an anode structure. Geometrically this can be achieved quite easily and the anode can be behind the target to avoid coating build-up and possible defects / flake generation. The presentation will demonstrate that such an arrangement can reduce the temperature of the substrate by up to 50% with DC power modes. This allows higher production speeds during web coating, and improves process stability. Additionally for a two cathode arrangements, the same method can allow a pulsed DC power mode instead of an AC type switching power; even for high dielectric layers such as SiO2 and Al2O3. Being able to use pulsed DC power with such active anodes improves flexibility and control of the process when compared to AC type power.