Method of polishing carrier plate, carrier plate, and method of polishing semiconductor wafer

A method of polishing a carrier plate included in a double-sided polishing apparatus that includes:

• the carrier plate having a wafer holding hole for holding a semiconductor wafer;
• and an upper surface plate and a lower surface plate facing each other with the carrier plate sandwiched therebetween and each provided with a polishing pad on a surface thereof and that supplies a polishing liquid while relatively rotating the carrier plate, the upper surface plate, and the lower surface plate to perform chemical mechanical polishing simultaneously on front and back sides of the semiconductor wafer held in the wafer holding hole, the method comprising:
• sandwiching a carrier plate unused after manufacture and to be polished between the upper surface plate and the lower surface plate in the double-sided polishing apparatus for performing chemical mechanical polishing simultaneously on the front and back sides of the semiconductor wafer, and supplying a polishing liquid while relatively rotating the carrier plate to be polished, the upper surface plate, and the lower surface plate to polish both sides of the carrier plate to be polished, wherein
• a polishing pad including, on a surface thereof, an abrasive grain-containing layer in which abrasive grains of 2 μm or more in grain size are embedded is used as the polishing pad in the double-sided polishing apparatus.