Polishing apparatus and method of reconditioning polishing pad

1. A polishing apparatus comprising:

a head that holds a semiconductor wafer;

a polishing pad that polishes a surface to be polished of the semiconductor wafer held by the head;

a disk-shaped dresser that reconditions the polishing pad by cutting the polishing pad; and

a dresser oscillator that supports at least two said disk-shaped dressers so that the disk-shaped dressers can rotate on their own axes, and that simultaneously oscillates the disk-shaped dressers on the polishing pad,

wherein the dresser oscillator separately supports each of the disk-shaped dressers and has a dresser position controller that controls the position of each of the disk-shaped dressers so that oscillations of each of the disk-shaped dressers are in synchronization with each other, and

wherein a rotation axis of each of the disk-shaped dressers is rotatably supported in a dresser supporting plate, the dresser supporting plate has another rotation axis that differs from the rotation axis of each of the disk-shaped dressers, and the dresser supporting plate rotates on its own rotation axis.

2. The polishing apparatus according to claim 1 , wherein the dresser oscillator has one arm which causes the dresser supporting plate to move onto the polishing pad.

3. A method of reconditioning a polishing pad, the method comprising:

providing a polishing apparatus comprising a polishing pad that polishes a surface, which is to be polished, of a semiconductor wafer and a disk-shaped dresser that reconditions the polishing pad by cutting the polishing pad; and

reconditioning the polishing pad by use of the disk-shaped dresser before and after the polishing of the surface to be polished,

wherein at least two said disk-shaped dressers are simultaneously moved onto the polishing pad, each of the disk-shaped dressers is caused to rotate on its own axis, and the disk-shaped dressers are caused to oscillate simultaneously on the polishing pad,

wherein oscillations of each of the disk-shaped dressers are caused to be in synchronization with each other, and

wherein a rotation axis of each of the disk-shaped dressers is rotatably supported in a dresser supporting plate, the dresser supporting plate has another rotation axis that differs from the rotation axis of each of the disk-shaped dressers, and the dresser supporting plate rotates on its own rotation axis.

4. The polishing method according to claim 3 , wherein the dresser oscillator has one arm which causes the dresser supporting plate to move onto the polishing pad.

5. A polishing apparatus comprising:

a head that holds a semiconductor wafer;

a polishing pad that rotates and polishes a surface to be polished of the semiconductor wafer held by the head, said head holding the semiconductor wafer against a top surface of the polishing pad;

a disk-shaped dresser downstream of the head in a direction of rotation of the polishing pad that reconditions the polishing pad by cutting the top surface of the polishing pad; and

a dresser oscillator that supports at least two said disk-shaped dressers so that the disk-shaped dressers can rotate on their own axes, and that simultaneously reciprocally rotates the disk-shaped dressers on the polishing pad,

wherein a rotation axis of each of the disk-shaped dressers is rotatably supported in a dresser supporting plate, the dresser supporting plate has another rotation axis that differs from the rotation axis of each of the disk-shaped dressers, and the dresser supporting plate rotates on its own rotation axis.

6. The polishing apparatus according to claim 5 , wherein the dresser oscillator has one arm which causes the dresser supporting plate to move onto the polishing pad.