| 摘要 |
A plasma confining magnetic field (202, 302) is generated over the sputtering region (105, 106) of a sputtering target (40) with a critical field line (202b, 302b) which determines the shape of the plasma (204, 304). The critical field line is progressively flattened over the course of the life of the target as the target erodes. Preferably, the magnet (51, 52) is configured with poles (57, 61, 65) spaced around the portion of the target below the sputtering region to provide a magnetic field that flattens as its strength decreases. A regulated power supply (122) maintains a regulated power level that is increased as the target erodes to maintain a constant deposition rate. The voltage delivered by the power supply is maintained at or above a constant level by progressively decreasing the current to an electromagnet (52, 54) to progressively reduce the field strength and flatten the field. As a result of the invention, the erosion groove of the target is broadened and the number of wafers coated by the target during its life is increased. |
