1. Field of the Invention
The present invention relates to a dresser for dressing a polishing surface of a platen of a polishing apparatus and a dressing apparatus for the same.
2. Description of the Related Art
In a polishing apparatus, for example, a two-side polishing apparatus, an upper platen and lower platen gripping workpieces held in carriers from above and below are made to rotate in mutually opposite directions so as to simultaneously polish the two surfaces of the workpieces by pads attached to the upper platen and lower platen.
If this apparatus is used for a long time, however, the abrasive, chips, etc. penetrate and clog the pads and cause the polishing rate to remarkably fall. Therefore, "dressing" has been performed to scrape off the abrasive etc. clogging the pads.
FIG. 18 is a schematic side view of an example of the dressing technique of the related art, while FIG. 19 is a schematic side view of another example.
The technique shown in FIG. 18 is one in which the platen 100 which has become clogged is removed from the polishing apparatus and the surface of the pad 101 is shaved by a knife edge 200 to scrape off the abrasive etc. clogging the pad 101.
As opposed to this, the technique shown in FIG. 19 is the technique described in Japanese Unexamined Patent Publication (Kokai) No. 4-364730, where rotating brushes 300 are pressed against the pad 101 of the rotating platen 100 and, in that state, the brushes 300 are moved in the radial direction so as to scrape off the abrasive etc. impregnated in the pad 101.
Further, as similar art, there is the technique described in Japanese Unexamined Utility Model Publication (Kokai) No. 54-129891.
In the above related art, however, there were the following problems:
In the technique shown in FIG. 18, it was necessary to remove the platen 100 from the polishing apparatus each time so trouble was involved. Further, since the worker had to perform the dressing manually, the burden on the worker was high.
On the other hand, in the technique shown in FIG. 19 and the technique described in Japanese Unexamined Utility Model Publication (Kokai) No. 54-129891, the dressing was performed automatically, so the burden on the worker was lightened, but since just brushes 300 were used to try to scrape off the abrasive etc., a sufficient dressing effect could not be obtained.