Polishing method and polishing apparatus
A polishing method can safely detach and lift up a workpiece from a polishing surface without carrying out the operation of making the workpiece overhang the polishing surface. The polishing method includes carrying out processing of a surface to be polished of a workpiece by supplying a liquid to a polishing surface while pressing the surface to be polished of the workpiece held by a holding device against the polishing surface and moving the workpiece and the polishing surface relative to each other, attracting the workpiece after the processing to the holding device while supplying the liquid to the polishing surface at a decreased flow rate, thereby detaching the workpiece from the polishing surface, and lifting up the holding device together with the workpiece on confirmation of detachment of the workpiece from the polishing surface and attachment of the workpiece to the holding device.
1. A polishing method for polishing a workpiece, the polishing method comprising:
carrying out processing of a surface to be polished of a workpiece by supplying a liquid to a polishing surface of a turntable and pressing the surface to be polished of the workpiece held by a holding device against the polishing surface while moving the workpiece and the polishing surface relative to each other at a first relative speed;
attracting the workpiece after the processing to the holding device while moving the workpiece and the polishing surface at a second relative speed, which is lower than the first relative speed, thereby detaching the workpiece from the polishing surface; and
lifting up the holding device together with the workpiece.
2. The polishing method according to claim 1 , wherein the turntable having the polishing surface is being rotated during polishing of the workpiece, and a rotational speed of the turntable is decreased to 30 rpm or lower, or a relative speed at a center point of the workpiece is decreased to 613 mm/sec or lower in the step of attracting the workpiece.
3. The polishing method according to claim 1 , wherein the step of attracting the workpiece comprises applying a vacuum to the workpiece thereby attracting the workpiece, a degree of vacuum in the applying of the vacuum being stepwise increased until the workpiece detaches from the polishing surface.
4. The polishing method according to claim 1 , wherein detachment of the workpiece from the polishing surface and attachment of the workpiece to the holding device is confirmed based on a decrease in electric current in a motor that drives the turntable having the polishing surface or a decrease in electric current in a motor that drives the holding device.
5. The polishing method according to claim 1 , wherein detachment of the workpiece from the polishing surface and attachment of the workpiece to the holding device is confirmed by detecting a change in a thickness of a liquid film covering the polishing surface.
6. The polishing method according to claim 1 , wherein detachment of the workpiece from the polishing surface and attachment of the workpiece to the holding device is confirmed based on a change in a force that draws the holding device downward.
7. The polishing method according to claim 1 , wherein detachment of the workpiece from the polishing surface and attachment of the workpiece to the holding device is confirmed by detecting a distance between the workpiece and the polishing surface.
8. The polishing method according to claim 7 , wherein the distance between the workpiece and the polishing surface is detected with an eddy current sensor.
9. The polishing method according to claim 1 , wherein the workpiece is lifted up together with the holding device while stepwise changing the height of the holding device.
10. The polishing method according to claim 1 , wherein a force to lift up the holding device together with the workpiece is stepwise changed.