Patent Number: 
Section: claims

1. An X-ray exposure apparatus for exposing a substrate to a pattern in an atmosphere of helium, said apparatus comprising:a chamber;a substituting unit for substituting a gas in said chamber from nitrogen to helium;a stage, provided in said chamber, which holds and moves the substrate;a static pressure gas bearing, provided in said chamber, which supports said stage;a gas supply unit for supplying the helium to said static pressure gas bearing;a control unit for controlling said gas supply unit to supply the helium to said static pressure gas bearing when said substituting unit substitutes the gas in said chamber from the nitrogen to the helium; anda bearing exhaust unit for exhausting the gas of said static pressure gas bearing. 2. An apparatus according to claim 1, further comprising an evacuating unit for evacuating said chamber by exhausting the gas therefrom when substituting the gas in said chamber from the nitrogen to the helium. 3. An apparatus according to claim 2, wherein said gas supply unit supplies the helium to said static pressure gas bearing before a start of exhausting the gas in said chamber. 4. An apparatus according to claim 2, wherein said gas supply unit supplies the helium to said static pressure gas bearing simultaneously with exhausting of the gas in said chamber. 5. An apparatus according to claim 2, wherein said gas supply unit supplies the helium to said static pressure gas bearing after a start of exhausting the gas in said chamber. 6. An apparatus according to claim 2, wherein said evacuating unit and the bearing exhaust unit are the same. 7. An X-ray exposure apparatus for exposing a substrate to a pattern in an atmosphere of helium, said apparatus comprising:a chamber;a substituting unit for exhausting nitrogen from said chamber and introducing the helium into said chamber;a stage, provided in said chamber, which holds and moves the substrate;a static pressure gas bearing, provided in said chamber, which supports said stage;a gas supply pipe for supplying a working gas to said static pressure gas bearing; anda bearing exhaust unit for exhausting a gas of said static pressure gas bearing through said gas supply pipe. 8. An X-ray exposure apparatus for exposing a substrate to a pattern in an atmosphere of helium, said apparatus comprising:a chamber;a positioning unit provided in said chamber to position the substrate;a substituting unit for substituting the helium for nitrogen in said chamber;a static pressure gas bearing, provided in said chamber, for supporting said positioning unit;a gas supply unit for supplying a working gas to said static pressure gas bearing;a control unit for controlling said gas supply unit to supply the helium to said static pressure gas bearing when substituting the gas in said chamber from the nitrogen to the helium; anda bearing exhaust unit for exhausting the gas of said static pressure gas bearing. 9. An apparatus according to claim 8, wherein said X-ray exposure apparatus employs a synchrotron radiation beam as an exposure beam. 10. An X-ray exposure apparatus for exposing a substrate to a pattern in an atmosphere of helium, said apparatus comprising:a chamber;a positioning unit provided in said chamber to position the substrate;a substituting unit for exhausting nitrogen from said chamber and introducing the helium into said chamber;a static pressure gas bearing, provided in said chamber, for supporting said positioning unit;a gas supply pipe for supplying a working gas to said static pressure gas bearing; anda bearing exhaust unit for exhausting a gas in said static pressure gas bearing through said gas supply pipe. 11. An apparatus according to claim 10, wherein said X-ray exposure apparatus uses a synchrotron radiation beam as an exposure beam. 12. An atmosphere substituting method of substituting an atmosphere in a chamber of an X-ray exposure apparatus for exposing a substrate to a pattern in an atmosphere of helium, the X-ray exposure apparatus having a stage, provided in the chamber, which holds and moves the substrate, and a static pressure gas bearing, provided in the chamber, which supports the stage, said method comprising:a substituting step of substituting a gas in the chamber from nitrogen to the helium;a bearing exhaust step of exhausting, during said substituting step, the nitrogen of the static pressure gas bearing in the chamber; anda gas supply step of supplying the helium to the static pressure gas bearing with a gas supply unit. 13. A method according to claim 12, further comprising an evacuating step of evacuating the chamber by exhausting the gas therefrom when substituting the gas in the chamber from the nitrogen to the helium. 14. A method according to claim 13, wherein the helium is supplied in said gas supply step before a start of exhausting the gas in said evacuating step. 15. A method according to claim 13, wherein the helium is supplied in said gas supply step simultaneously with exhausting of the gas in said evacuating step. 16. A method according to claim 13, wherein the helium is supplied in said gas supply step after a start of exhausting the gas in said evacuating step. 17. A device manufacturing method comprising a substituting step of substituting a gas in a chamber, incorporating a positioning apparatus supported by a static pressure gas bearing, from nitrogen to helium, and an X-ray exposure step of positioning a substrate with the positioning apparatus and exposing the substrate to a pattern after said substituting step, said method comprising:a bearing exhaust step of exhausting, during said substituting step, the nitrogen of the static pressure gas bearing; anda gas supply step of supplying the helium to the static pressure gas bearing with a gas supply unit. 18. A method according to claim 17, further comprising an evacuating step of evacuating the chamber by exhausting the gas therefrom when substituting the gas in said substituting step, wherein the helium is supplied in said gas supply step before a start of, simultaneously with, or after a start of exhausting the gas in said evacuating step. 19. A method according to claim 18, wherein in said bearing exhaust step, the gas of the static pressure gas bearing is exhausted through a pipe connected thereto, the gas being exhausted simultaneously with exhausting in said evacuating step. 20. A method according to claim 19, wherein an exposure in said X-ray exposure step is performed by using a synchrotron radiation beam. 21. A method according to claim 17, wherein the gas is exhausted in said bearing exhaust step after the helium is supplied in said gas supply step. 22. A device manufacturing method comprising a substituting step of substituting a gas in a chamber, incorporating a positioning apparatus supported by a static pressure gas bearing, by exhausting nitrogen from the chamber and introducing a helium into the chamber, and an X-ray exposure step of positioning a substrate with the positioning apparatus and exposing the substrate to a pattern after said substituting step, said method comprising:a bearing exhaust step of exhausting the gas of the static pressure gas bearing through a pipe connected thereto simultaneously with exhausting the gas in said substituting step. 23. A method according to claim 22, wherein an exposure in said X-ray exposure step is performed by using a synchrotron radiation beam.