Patent ID: 6190517
Filing Date: 2001-02-20
Classification: H01F,H01J

Abstract:
An electro-magnet array for use in a sputtering apparatus comprising:a magnetisable core member extending substantially horizontally and having magnetisable outward projections arranged as at least two pairs of symmetrically opposed projections projecting outwardly and radially symmetrically from the magnetisable core member;a pole piece associated with each projection and vertically displaced with respect thereto;magnetisable coupling means arranged to couple each pole piece magnetically to its respective projection; anda magnetising coil around each projection arranged for producing a magnetic field aligned substantially with a horizontal axis of symmetry of its respective projection in dependence upon the direction of flow of electric current through the magnetising coil;the magnetising coils being arranged so that, upon energisation, the respective magnetic field of one coil of a pair of projections can produce a south pole at an inward side of its respective pole piece while the magnetic field of the coil of the other projection of the pair produces a north pole at an inward side of its respective pole piece and so that, at any moment, at least two inwardly facing south poles are produced on the pole pieces on one side of a vertical place of symmetry through the array and an equal number of inwardly facing north poles are produced on the pole pieces on the other side of the vertical plane of symmetry, the vertical plane of symmetry passing between adjacent pole pieces.