Apparatus for holding wafer cassettes in a cassette in a cassette tub during a chemical mechanical polishing process

A cassette tub for holding at least one wafer cassette in a tilted position for accessing by a robot blade comprising:

• a tub body of generally rectangular shape with an open top for holding a quantity of water therein, said tub body having two opposing longitudinal sidewalls;
• a support structure affixed to a process machine onto which the tub body is situated equipped with two mounting rails along said longitudinal sidewalls each having mounting holes for receiving at least one cassette tub pin assembly;
• at least one wafer cassette having a planar base portion for engaging said at least one cassette tub pin assembly such that the at least one wafer cassette is maintained at a tilted position of between about 3° and about 7° when measured from a horizontal plane;
• and
• at least one cassette tub pin assembly each having a straight section for engaging the planar base portion of a wafer cassette and two 90° bent sections each having a screw hole at a tip portion, each screw hole for engaging one of said mounting holes provided in one of the mounting rails by a screw.