Exposure apparatus, exposure method using the same and method of manufacture of circuit device

• US 6,414,743 B1
• Filed: 10/18/1999
• Issued: 07/02/2002
• Est. Priority Date: 04/18/1997
• Status: Expired due to Fees

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Nishi, Kenji, Kiuchi, Toru
• Primary Examiner(s): Adams, Russell
• Assistant Examiner(s): NGUYEN, HUNG
• Application Number:
  US09/420,000
• Time in Patent Office: 988 Days
• Field of Search: 355/30, 355/53, 355/55, 355/68-71, 355/77, 250/548, 378/34-35
• US Class Current: 355/69
• CPC Class Codes: G03F 7/70058 Mask illumination systems
• CPC Class Codes: G03F 7/70066 Size and form of the illuminated area in the mask plane, e.g. reticle masking blades or blinds
• CPC Class Codes: G03F 7/70225 Optical aspects of catadioptric systems, i.e. comprising reflective and refractive elements
• CPC Class Codes: G03F 7/70241 Optical aspects of refractive lens systems, i.e. comprising only refractive elements
• CPC Class Codes: G03F 7/70258 Projection system adjustments, e.g. adjustments during exposure or alignment during assembly of projection system
• CPC Class Codes: G03F 7/70358 Scanning exposure, i.e. relative movement of patterned beam and workpiece during imaging
• CPC Class Codes: G03F 7/70558 Dose control, i.e. achievement of a desired dose
• CPC Class Codes: G03F 7/70591 Testing optical components
• CPC Class Codes: G03F 7/7085 Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load
• CPC Class Codes: G03F 7/70941 Stray fields and charges, e.g. stray light, scattered light, flare, transmission loss

Abstract

An exposure method for irradiating a mask with an illumination light through an illumination optical system and exposing photosensitive substrate to the illumination light through a projection optical system including the steps of supplying gas having less absorption of the illumination light to a light path of the illumination light, at least a portion of the illumination optical system and the projection optical system; and changing an exposing condition for the photosensitive substrate in accordance with a variation in transmittance or in reflectance of at least one of the illumination optical system and the projection optical system, resulting from irradiation of the illumination light and attenuation of the illumination light in the light path.

Claims

1. An exposure method for irradiating a mask with an illumination light through an illumination optical system and exposing photosensitive substrate to the illumination light through a projection optical system;

comprising the steps of;

supplying gas having less absorption of the illumination light to a light path of the illumination light, at least a portion of the illumination optical system and the projection optical system; and

changing an exposing condition for the photosensitive substrate in accordance with a variation in transmittance or in reflectance of at least one of the illumination optical system and the projection optical system, resulting from irradiation of the illumination light and attenuation of the illumination light in the light path.

2. The method as claimed in claim 1, wherein an image characteristic of a pattern on the mask is further adjusted in accordance with a variation in an imaging characteristic of the projection optical system attendant upon the variation in transmittance or reflectance.

3. The method as claimed in claim 1, wherein the gas having less absorption of the illumination light is nitrogen or helium gas.

4. The method as claimed in claim 3, wherein the gas having less absorption of the illumination light flows forcedly into the light path.

5. The method as claimed in claim 1, wherein attenuation of the illumination light is caused by substrates present in the light path, which absorb the illumination light.

6. An exposure method comprising:

supplying gas having less absorption of an exposure light to a housing which forms a light path of an exposure light between a light source and a photosensitive substrate and which houses optical elements disposed in the light path;

filling the light path with the gas; and

changing an exposing condition for the substrate in accordance with an energy of the exposure light passed through the light path, which varies according to substances present in the light path which absorb the exposure light, and to a variation in the characteristics of the optical elements or a membrane material deposited on a surface of the optical element.

7. The method as claimed in claim 6, wherein the substances which absorb the exposure light include a material which differs from the membrane material deposited on the surface of the optical elements.

8. The method as claimed in claim 7, wherein the substances which absorb the exposure light result from a substance present in the light path.

9. The method as claimed in claim 6, wherein the housing houses an illumination optical system, comprised of a combination of the optical elements, which irradiates the mask on which a pattern is formed with the exposure light from the light source;

and wherein the gas having less absorption of the exposure light is supplied to a space between the optical elements.

10. The method as claimed in claim 9, wherein the variation in the energy includes a variation in attenuation factor of the illumination optical system.

11. The method as claimed in claim 9, wherein the illumination optical system comprises at least one of reflection optical elements which reflect the exposure light and transmission optical elements which transmit the exposure light, as the optical elements.

12. The method as claimed in claim 6, wherein the housing houses a projection optical system, comprised of a combination of the optical elements, which projects a patten formed on the mask onto the substrate, and wherein the gas having less absorption of the exposure light is supplied to a space between the optical elements.

13. The method as claimed in claim 12, wherein the variation in the energy includes a variation in attenuation factor of the projection optical system.

14. The method as claimed in claim 12, wherein the projection optical system comprises at least one of reflection optical elements which reflect the exposure light and transmission optical elements which transmit the exposure light, as the optical elements.

15. The method as claimed in claim 6, wherein the variation in the energy is computed on the basis of the energy prior to passing through the housing and the energy after passing through the housing.

16. The method as claimed in claim 6, wherein the gas having less absorption of an exposure light flows into the lightpath.

17. The method as claimed in claim 16, wherein the gas having less absorption of an exposure light is an inert gas.

18. The method as claimed in claim 6, wherein the exposure light comprises an ultraviolet, and wherein the substances which absorb the exposure light comprise impurities which contain at least one of water molecules and hydrocarbon molecules.

19. The method as claimed in claim 6, wherein the substrate and the mask are scanned relative to a field of the projection optical system.

20. The method as claimed in claim 19, wherein the exposing condition comprises at least one of an intensity of the exposure light on the substrate, a velocity for scanning the substrate, and a width of an illumination region of the exposure light relating to a scanning direction of the substrate.

21. The method as claimed in claim 19, wherein the exposure light is a pulse light, and wherein the exposing condition is set by adjusting at least one of an oscillating frequency of the pulse light, and intensity of the exposure light on the substrate, a velocity for scanning the substrate, and a width of an illumination region of the exposure light relating to a scanning direction of the substrate.