What is claimed is:
1. A polishing head of a CMP apparatus, comprising:
a polishing pad;
a first air bag and a second air bag, which are in contact with a rear surface of a wafer mounted on a front surface of the polishing pad, and which are configured to press a front surface of the wafer against the polishing pad; and
a top ring surrounding the first air bag, the second air bag, and the wafer,
the first air bag, which is in contact with a central portion of the wafer, and the second air bag, which is in contact with a peripheral portion of the wafer, being separate bag bodies, and
the first air bag, which is in contact with the central portion of the wafer, has a first film thickness, and the second air bag, which is in contact with the peripheral portion of the wafer, has a second film thickness that is thicker than the first film thickness.
2. A polishing head according to claim 1 , wherein the first air bag is a circular air bag in plan view, and the second air bag in plan view is a torus-shaped air bag arranged around the circular air bag.
3. A polishing head according to claim 1 , wherein the first air bag is a circular air bag in plan view, and the second air bag in plan view is an aggregation of a plurality of circular air bags arranged around the first air bag and each smaller than the first air bag in size.
4. A polishing head according to claim 1 , wherein the first air bag is an aggregation of a plurality of circular air bags in plan view, and the second air bag in plan view is an aggregation of a plurality of circular air bags arranged around the first air bag.
5. A polishing head according to claim 1 , wherein the first air bag is a circular air bag in plan view, and the second air bag in plan view is a coiled-hose shape air bag arranged around the circular air bag.
6. A polishing head according to claim 1 , wherein the first air bag is a first coiled-hose shape air bag in plan view, and the second air bag in plan view is an aggregation of a plurality of second coiled-hose shape air bags arranged around the first coiled-hose shape air bag and each smaller than the first coiled-hose shape air bag in size.
7. A polishing head according to claim 1 , wherein the first air bag is an aggregation of a plurality of coiled-hose shape air bags in plan view, and the second air bag in plan view is an aggregation of a plurality of coiled-hose shape air bags arranged around the first coiled-hose shape air bag.