Sputtering cathode - includes electrically floating dark-space screen to prevent target contamination

摘要

The sputtering cathode working on the magnetron principle has a cathode base (1) which is provided with a target (3) with sputter and peripheral surfaces. A magnetic system (6) with poles (8) lies below the target. The boundary regions of the target outside the erosion zone are covered by a dark-space screen (11). The dark-space screen (11) is electrically floating and its horizontal projections and vertical walls (29,30) are sepd. from the target (3) by means of a gap. This gap is so wide that no plasma can ignite between the screen and target, and the gap itself cannot be closed by material scattered back. A baseplate (2) carrying the firmly attached target (3) is mounted on the cathode base (1). The parts of the baseplate and cathode base subjected to voltage are surrounded by the electrically floating screen (11). This screen is made of an electrically conductive material and is electrically insulated from the cathode and the target. Such insulation is achieved by means of distance pieces (20) made of a nonconductive material. The top surface (21) of the screen lies on the same level as the target surface (9). Alternatively, the surface (21) can lie below the level of the target surface. On the inside of the screen there are recesses (26) for accommodating (at least partially) the fixing elements (27). USE/ADVANTAGE - In installations serving for sputtering substrates of various kinds. It prevents target contamination with reaction prods., enhances process stability and allows coatings with an improved quality to be produced.