APPLYING WEIGHTED GREY RELATIONAL ANALYSIS AND AUTO CLUSTERING TECHNIQUE TO MISSING VALUES COMPLETION

A plasma diffusion control apparatus is provided with a plurality of wires through which current flows in parallel so that lines of magnetic force are generated in a direction parallel to the plasma wall of the diffusion chamber wall. It is preferable that the wires are located in the neighborhood of the diffusion chamber at equal intervals, and arranged so that the direction of the magnetic field generated by wires are parallel to the direction of movement of the plasma. Since the magnetic field is formed in a direction parallel to the inner wall of the diffusion chamber, it is possible to prevent the diffusion of the plasma to the chamber wall. As a result there is no region which is influenced by strong local magnetic fields perpendicular to the plasma chamber wall, so that it is possible to solve the problems caused by substantial amounts of polymer deposition on the inner wall of the plasma diffusion chamber.