Method and apparatus for polishing a substrate

A method of polishing a substrate by a polishing apparatus comprising a polishing table having a polishing surface, a top ring for holding a substrate and pressing the substrate against said polishing surface, and a vertically movable mechanism for moving said top ring in a vertical direction, wherein said top ring comprises at least one elastic membrane configured to form a pressure chamber to be supplied with a pressurized fluid, a top ring body for holding said membrane, and a retainer ring configured to hold a peripheral portion of the substrate and to be movable independently relative to said to ring body, said membrane being configured to press the substrate against said polishing surface under a fluid pressure by supplying the pressurized fluid to said pressure chamber, said method comprising:

• moving said top ring body and said membrane to a predetermined height before the substrate is pressed against said polishing surface, wherein said predetermined height is a height of said membrane that forms a clearance of 0.1 mm to 1.2 mm between the substrate and said polishing surface in a state in which the substrate is attached to and held by said membrane and a lower surface of said top ring body and an upper surface of said membrane are in contact with each other;
• applying a first pressure to said pressure chamber until the substrate is brought into contact with said polishing surface while maintaining said top ring body at said predetermined height;
• and
• applying a second pressure higher than said first pressure to said pressure chamber after the substrate is brought into contact with said polishing surface and when the substrate starts to be polished, and pressing the substrate against said polishing surface at said second pressure to polish the substrate, while maintaining said top ring body at said predetermined height.

A method of polishing a substrate by a polishing apparatus comprising a polishing table having a polishing surface, a top ring for holding a substrate and pressing the substrate against said polishing surface, and a vertically movable mechanism for moving said top ring in a vertical direction, wherein said top ring comprises at least one elastic membrane configured to form a pressure chamber to be supplied with a pressurized fluid, and a top ring body configured to hold said membrane, said membrane being configured to press the substrate against said polishing surface under a fluid pressure by supplying the pressurized fluid to said pressure chamber, said method comprising:

• conducting a polishing process to obtain a polishing profile in a state in which said top ring body is maintained at a polishing height and said membrane presses the substrate against said polishing surface by the pressurized fluid supplied to said pressure chamber;
• moving said top ring body from the polishing height to a predetermined height that is different than the polishing height in a state in which the substrate continues to be brought in contact with said polishing surface after the polishing process to obtain the polishing profile is finished, wherein said predetermined height is a height of said top ring body that forms a clearance of 0.1 mm and 1.7 mm between said top ring body and said membrane;
• and
• vacuum-chucking the substrate to said membrane from said polishing surface and holding the substrate by said membrane after said moving of said top ring body or simultaneously with said moving of said top ring body.