Apparatus and method for the chemical mechanical polishing of the surface of circular flat workpieces, in particular semi-conductor wafers

A method for the chemical-mechanical polishing of the surface of semi-conductor wafers by means of two polishing stations, each having a polishing table, two chuck for each polishing station which independently from each other can be moved vertically and horizontally, four loading surfaces having a center lying on a circle which loading surfaces can be rotated about a vertical axis, the loading surfaces being located between the polishing stations such that in predetermined common rotary positions which are spaced about an angle of 90° or a multitude of 90°, two loading surfaces are aligned with the linear transport path of two chucks belonging to a polishing station, in a predetermined rotary position the loading surfaces being adapted to be loaded with a loading and unloading means with a workpiece or to remove a workpiece from the loading surfaces, comprising the following method steps:

• a) after loading two loading surfaces with a first and a second workpiece the loading surface are rotated about 90°, whereby the workpieces are aligned with the first polishing station and are moved from the chucks to the first polishing station to the polishing tables in order to carry out a first polishing step
• b) after removal of the first and second workpiece by the chucks, a third and a fourth workpiece are placed on the associated loading surfaces and by rotation of the loading surfaces about 90° are aligned to the second polishing station, whereafter the first and second workpiece are removed from the first polishing station by the chucks and are placed on the association free loading surfaces
• c) after rotation of the loading surfaces about 180° the first and the second workpiece are carried to the second polishing station and the third and fourth workpiece are carried to the first polishing station by the associated chucks
• d) after finishing of the polishing process the workpieces are placed on the association loading surfaces and the third and fourth workpiece are aligned with the second polishing station and the first and second workpiece are removed by the loading and unloading means so that thereafter a loading with a fifth and sixth workpiece can take place.