Polishing apparatus and method

• US 20090142996A1
• Filed: 11/24/2008
• Published: 06/04/2009
• Est. Priority Date: 11/29/2007
• Status: Active Grant

• Current Assignee: Ebara Corporation
• Original Assignee: Ebara Corporation
• Inventors: Yasuda, Hozumi, Fukushima, Makoto, Togawa, Tetsuji
• Granted Patent: US 8,070,560 B2
• Time in Patent Office: Days
• US Class Current: 451/60
• CPC Class Codes: B24B 37/30 for single side lapping of plane surfaces

Abstract

A polishing apparatus is used for polishing a substrate such as a semiconductor wafer to a flat mirror finish. The polishing apparatus includes a polishing table having a polishing surface, a polishing head having at least one elastic membrane configured to form a plurality of pressure chambers for being supplied with a pressurized fluid, and a controller configured to control supply of the pressurized fluid to the pressure chambers. The controller controls supply of the pressurized fluid so that the pressurized fluid is supplied first to the pressure chamber located at a central portion of the substrate when the substrate is brought into contact with the polishing surface, and then the pressurized fluid is supplied to the pressure chamber located at a radially outer side of the pressure chamber located at the central portion of the substrate.

Claims

1. An apparatus for polishing a substrate, comprising:

a polishing table having a polishing surface;

a polishing head having at least one elastic membrane configured to form a plurality of pressure chambers for being supplied with a pressurized fluid, said elastic membrane being configured to press the substrate against said polishing surface under a fluid pressure when said pressure chambers are supplied with the pressurized fluid; and

a controller configured to control supply of the pressurized fluid to said pressure chambers;

wherein said controller controls supply of the pressurized fluid so that the pressurized fluid is supplied first to the pressure chamber located at a central portion of the substrate when the substrate is brought into contact with said polishing surface, and then the pressurized fluid is supplied to the pressure chamber located at a radially outer side of said pressure chamber located at the central portion of the substrate.

2. The apparatus according to claim 1, wherein said controller controls said polishing head to lower said polishing head to a preset polishing position, said preset polishing position being defined as a position where a gap is formed between a lower surface of the substrate held by said polishing head and said polishing surface before said polishing chamber located at the central portion of the substrate is supplied with the pressurized fluid.

3. The apparatus according to claim 2, wherein said polishing head comprises a top ring body to which said elastic membrane is attached, and a retainer ring provided at a peripheral portion of said top ring body;

and

wherein when said polishing head is lowered to said preset polishing position, said retainer ring is brought into contact with said polishing surface.

4. An apparatus for polishing a substrate, comprising:

a polishing table having a polishing surface;

a polishing head having at least one elastic membrane configured to form a pressure chamber for being supplied with a pressurized fluid, said elastic membrane being configured to press the substrate against said polishing surface under a fluid pressure when said pressure chamber is supplied with the pressurized fluid; and

a controller configured to control supply of the pressurized fluid to said pressure chamber;

wherein said controller controls supply of the pressurized fluid so that the pressurized fluid is supplied first from a supply hole located at a position corresponding to a central portion of the substrate to said pressure chamber when the substrate is brought into contact with said polishing surface, and then the pressurized fluid is supplied from a supply hole located at a radially outer side of said supply hole located at the position corresponding to the central portion of the substrate to said pressure chamber.

5. The apparatus according to claim 4, wherein said controller controls said polishing head to lower said polishing head to a preset polishing position, said preset polishing position being defined as a position where a gap is formed between a lower surface of the substrate held by said polishing head and said polishing surface before said polishing chamber is supplied with the pressurized fluid.

6. The apparatus according to claim 5, wherein said polishing head comprises a top ring body to which said elastic membrane is attached, and a retainer ring provided at a peripheral portion of said top ring body;

and

wherein when said polishing head is lowered to said preset polishing position, said retainer ring is brought into contact with said polishing surface.

7. A method of polishing a substrate, comprising:

holding a substrate by a polishing head and bringing the substrate into contact with a polishing surface of a polishing table by said polishing head, said polishing head having a plurality of pressure chambers formed by an elastic membrane; and

pressing the substrate against said polishing surface to polish the substrate by supplying a pressurized fluid to said pressure chambers;

wherein the pressurized fluid is supplied first to the pressure chamber located at a central portion of the substrate when the substrate is brought into contact with said polishing surface, and then the pressurized fluid is supplied to the pressure chamber located at a radially outer side of said pressure chamber located at the central portion of the substrate.

8. The method according to claim 7, further comprising:

lowering said polishing head to a preset polishing position, said preset polishing position being defined as a position where a gap is formed between a lower surface of the substrate held by said polishing head and said polishing surface before said polishing chamber located at the central portion of the substrate is supplied with the pressurized fluid.

9. The method according to claim 8, wherein said polishing head comprises a top ring body to which said elastic membrane is attached, and a retainer ring provided at a peripheral portion of said top ring body;

and

wherein when said polishing head is lowered to said preset polishing position, said retainer ring is brought into contact with said polishing surface.

10. A method of polishing a substrate, comprising:

holding a substrate by a polishing head and bringing the substrate into contact with a polishing surface of a polishing table by said polishing head, said polishing head having a pressure chamber formed by an elastic membrane; and

pressing the substrate against said polishing surface to polish the substrate by supplying a pressurized fluid from a plurality of supply holes provided at positions corresponding to different radial positions of the substrate to said pressure chamber;

wherein the pressurized fluid is supplied first from the supply hole located at the position corresponding to a central portion of the substrate to said pressure chamber when the substrate is brought into contact with said polishing surface, and then the pressurized fluid is supplied from the supply hole located at a radially outer side of said supply hole located at the position corresponding to the central portion of the substrate to said pressure chamber.

11. The method according to claim 10, further comprising:

lowering said polishing head to a preset polishing position, said preset polishing position being defined as a position where a gap is formed between a lower surface of the substrate held by said polishing head and said polishing surface before said polishing chamber is supplied with the pressurized fluid.

12. The method according to claim 11, wherein said polishing head comprises a top ring body to which said elastic membrane is attached, and a retainer ring provided at a peripheral portion of said top ring body;

and

wherein when said polishing head is lowered to said preset polishing position, said retainer ring is brought into contact with said polishing surface.

13. An apparatus for polishing a substrate, comprising:

a polishing table having a polishing surface;

a polishing head having at least one elastic membrane configured to form a plurality of pressure chambers for being supplied with a pressurized fluid, said elastic membrane being configured to press the substrate against said polishing surface under a fluid pressure when said pressure chambers are supplied with the pressurized fluid; and

a diaphragm configured to cover at least part of said elastic membrane and extend over the two adjacent pressure chambers, said diaphragm being composed of a material having higher rigidity than said elastic membrane;

wherein said diaphragm has an area of not less than 10 mm from a boundary between said two pressure chambers both to an inner circumferential side and to an outer circumferential side of said elastic membrane.

14. The apparatus according to claim 13, wherein said diaphragm is fixed to said elastic membrane.

15. The apparatus according to claim 13, wherein said diaphragm is composed of one of resin comprising polyether ether ketone (PEEK), polyphenylene sulfide (PPS) or polyimide, metal comprising stainless steel or aluminium, and ceramics comprising alumina, zirconia, silicon carbide or silicon nitride.

16. The apparatus according to claim 15, wherein said elastic membrane is composed of ethylene propylene rubber (EPDM), polyurethane rubber, or silicone rubber.

17. The apparatus according to claim 13, wherein said diaphragm is configured to cover a substantially entire surface of said elastic membrane.

18. The apparatus according to claim 13, further comprising a second elastic membrane configured to cover said diaphragm, said second elastic membrane constituting a substrate holding surface configured to contact the substrate and hold the substrate.

19. The apparatus according to claim 18, wherein said second elastic membrane extends over said diaphragm and said elastic membrane configured to form said pressure chambers.

20. An apparatus for polishing a substrate, comprising:

a table having a polishing surface thereon;

a head for holding and pressing the substrate against the polishing surface, the head having at least one membrane for forming a plurality of cavities, to which a pressurized fluid can be supplied respectively, so as to press the substrate against the polishing surface;

a device for adjusting a pressure of the pressurized fluid; and

a device for controlling the device for adjusting the pressure of the pressurized fluid, thereby controlling a supply of the pressurized fluid to the plurality of cavities respectively;

wherein the device for controlling the device for adjusting the pressure of the pressurized fluid is operable so as to prevent the device for adjusting the pressure of the pressurized fluid from supplying the pressurized fluid to at least one cavity located near the edge of the membrane, while the substrate is in a first contact with the polishing surface.