US20020021432A1 - Method and instrument for measuring vacuum ultraviolet light beam, method of producing device and optical exposure apparatus - Google Patents
Method and instrument for measuring vacuum ultraviolet light beam, method of producing device and optical exposure apparatus Download PDFInfo
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- US20020021432A1 US20020021432A1 US09/808,049 US80804901A US2002021432A1 US 20020021432 A1 US20020021432 A1 US 20020021432A1 US 80804901 A US80804901 A US 80804901A US 2002021432 A1 US2002021432 A1 US 2002021432A1
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- light beam
- optical unit
- vacuum ultraviolet
- ultraviolet light
- lens system
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- 238000000034 method Methods 0.000 title claims abstract description 20
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 17
- 238000010926 purge Methods 0.000 claims abstract description 17
- 229910001873 dinitrogen Inorganic materials 0.000 claims abstract description 15
- 238000005286 illumination Methods 0.000 claims description 21
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 19
- 229920002120 photoresistant polymer Polymers 0.000 claims description 19
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 17
- 239000010436 fluorite Substances 0.000 claims description 16
- 239000010453 quartz Substances 0.000 claims description 15
- 239000000758 substrate Substances 0.000 claims description 11
- 238000005259 measurement Methods 0.000 abstract description 7
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 20
- 229910052753 mercury Inorganic materials 0.000 description 15
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 7
- 238000010586 diagram Methods 0.000 description 7
- 239000001301 oxygen Substances 0.000 description 7
- 229910052760 oxygen Inorganic materials 0.000 description 7
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 6
- 239000011521 glass Substances 0.000 description 5
- BJQHLKABXJIVAM-UHFFFAOYSA-N bis(2-ethylhexyl) phthalate Chemical compound CCCCC(CC)COC(=O)C1=CC=CC=C1C(=O)OCC(CC)CCCC BJQHLKABXJIVAM-UHFFFAOYSA-N 0.000 description 4
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- 230000000694 effects Effects 0.000 description 3
- 150000002222 fluorine compounds Chemical group 0.000 description 3
- 239000005337 ground glass Substances 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
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- 230000004075 alteration Effects 0.000 description 1
- XKRFYHLGVUSROY-UHFFFAOYSA-N argon Substances [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- ISQINHMJILFLAQ-UHFFFAOYSA-N argon hydrofluoride Chemical compound F.[Ar] ISQINHMJILFLAQ-UHFFFAOYSA-N 0.000 description 1
- -1 argon ion Chemical class 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 150000002221 fluorine Chemical class 0.000 description 1
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- 230000003595 spectral effect Effects 0.000 description 1
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Images
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70008—Production of exposure light, i.e. light sources
- G03F7/70025—Production of exposure light, i.e. light sources by lasers
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
- G03F7/7055—Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption
- G03F7/70558—Dose control, i.e. achievement of a desired dose
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
- G03F7/7055—Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption
- G03F7/70575—Wavelength control, e.g. control of bandwidth, multiple wavelength, selection of wavelength or matching of optical components to wavelength
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
- G03F7/70908—Hygiene, e.g. preventing apparatus pollution, mitigating effect of pollution or removing pollutants from apparatus
- G03F7/70933—Purge, e.g. exchanging fluid or gas to remove pollutants
Definitions
- the present invention relates to a method and an instrument for measuring a vacuum ultraviolet light beam having a wavelength not longer than 190 nm. Further, the present invention relates to a method for producing a device which method includes exposure treatment using the vacuum ultraviolet light beam and an optical exposure apparatus.
- the usable light source that can output a light beam having the shortest wavelength is an F 2 (molecular fluorine) laser.
- the F 2 laser beam is a sort of vacuum ultraviolet light beam having a wavelength not longer than 190 nm.
- an oscillated wavelength of the F 2 laser beam is 157.63 nm, and an oscillated spectral width of the F 2 laser beam is not longer than a few pico-meters.
- an optical exposure apparatus using the F 2 laser which will be called as an F 2 laser beam exposure system hereinafter, as a light source for exposure is provided.
- an instrument for measuring the F 2 laser beam which will be called as an F 2 laser beam measuring instrument hereinafter, is provided.
- An optical unit of each of those instruments includes a fluoride lens.
- the fluoride lens is a single lens composed from fluorite (CaF 2 ), which is suited for the F 2 laser beam.
- the F 2 laser beam tends to be easily absorbed into oxygen.
- an inside of a housing enclosing a light detector, an optical unit and so on is evacuated or purged by using nitrogen gas. Nitrogen purge is an operation of removing oxygen gas by using dry nitrogen gas.
- an instrument for measuring a light beam or an optical exposure apparatus should be adjusted such that an optical unit included in the instrument realizes its own aim. This is the same in a conventional F 2 laser beam measuring instrument or a conventional F 2 laser beam exposure system. However, a focal length of a single lens such as a fluoride lens is different in accordance with a wavelength of a light beam.
- the focal length for a light beam radiated from a low pressure mercury-vapor lamp and having a mercury resonance line (253.65 nm) is 253.65 mm
- the focal length for an F 2 laser beam having a wavelength of 157.63 nm is 214.60 mm.
- other light source except for the F 2 laser can not be used for adjustment of an optical unit, for example, adjustment of a position of the fluoride lens.
- the adjustment of the optical unit including the adjustment of the position of the fluoride lens must be carried out in the housing which has been evacuated or purged by using nitrogen gas. Therefore, operation of the adjustment is very difficult. This increases difficulty of measurement of the F 2 laser beam and prevents the spread of exposure treatment using the F 2 laser beam.
- an achromatic lens system designed optimally so as to fulfill achromatic conditions for both an F 2 laser beam and another light beam (for example, a mercury resonance line) is substituted for the fluoride lens.
- another light beam for example, a mercury resonance line
- fluoride lens In order to produce such an achromatic lens system, at least two materials of glass are required which are different in a dispersion value of a refractive index.
- fluorite was the only material of glass suited for the F 2 laser beam, and therefore, such an achromatic lens system could not be produced.
- the present invention has been accomplished in view of those problems.
- the first object of the present invention is to provide a method and an instrument for measuring a vacuum ultraviolet light beam wherein a position of an optical unit to be used for measuring the vacuum ultraviolet light beam can be easily adjusted so as to quickly measure the vacuum ultraviolet light beam.
- the second object of the present invention is to provide a method of producing a device and an optical exposure apparatus wherein a position of each of an illumination optical unit and a projection optical unit to be used for exposure treatment by using a vacuum ultraviolet light beam can be easily adjusted so as to quickly carry out the exposure treatment.
- a method of measuring a vacuum ultraviolet light beam having a wavelength not longer than 190 nm comprises: a first step of passing a regular light beam having a wavelength longer than 190 nm through an optical unit; a second step of adjusting a position of an achromatic lens system included in the optical unit such that the regular light beam which passed through the optical unit is focused on a light detector, the achromatic lens system being composed by combining one single lens produced from fluorite with another single lens produced from fluorine-doped synthetic quartz so as to fulfill achromatic conditions for both the regular light beam and the vacuum ultraviolet light beam; a third step of conducting, after the second step, one of (i) evacuating the inside of a housing for enclosing the optical unit and the light detector and (ii) purging the inside of the housing by using nitrogen gas; and a fourth step of focusing, after the third step, the vacuum ultraviolet light beam which passed through
- an instrument for measuring a vacuum ultraviolet light beam having a wavelength not longer than 190 nm comprises: a light detector for detecting both a regular light beam having a wavelength longer than 190 nm and the vacuum ultraviolet light beam; an optical unit including an achromatic lens system which is composed by combining one single lens produced from fluorite with another single lens produced from fluorine-doped synthetic quartz so as to fulfill achromatic conditions for both the regular light beam and the vacuum ultraviolet light beam; and a housing for enclosing the optical unit and the light detector in order to conduct one of (i) evacuating the inside of the housing and (ii) purging the inside of the housing by using nitrogen gas when measuring the vacuum ultraviolet light beam.
- a method of producing a device by using an illumination optical unit, a photo mask stage for fixing a photo mask in which a desired pattern is formed, a projection optical unit and a substrate stage for fixing a substrate in which a predetermined portion is coated with photo resist each enclosed in a housing comprises: a first step of passing a regular light beam having a wavelength longer than 190 nm through the illumination optical unit, the photo mask and the projection optical unit in this order; a second step of adjusting a position of an achromatic lens system included in each of the illumination optical unit and the projection optical unit such that the regular light beam which passed through the illumination optical unit, the photo mask and the projection optical unit in this order is focused on the photo resist, the achromatic lens system being composed by combining one single lens produced from fluorite with another single lens produced from fluorine-doped synthetic quartz so as to fulfill achromatic conditions for both the regular light beam and the vacuum ultraviolet light beam; a third step of evacuating the inside of
- an optical exposure apparatus comprises: an illumination optical unit including an achromatic lens system which is composed by combining one single lens produced from fluorite with another single lens produced from fluorine-doped synthetic quartz so as to fulfill achromatic conditions for both a regular light beam having a wavelength longer than 190 nm and a vacuum ultraviolet light beam having a wavelength not longer than 190 nm; a photo mask stage, arranged on an output side of the illumination optical unit, for fixing a photo mask in which a desired pattern is formed; an projection optical unit arranged on an output side of the photo mask stage, the projection optical unit including an achromatic lens system which is composed by combining one single lens produced from fluorite with another single lens produced from fluorine-doped synthetic quartz so as to fulfill achromatic conditions for both the regular light beam and the vacuum ultraviolet light beam; a substrate stage, arranged on an output side of the projection optical unit, for fixing a substrate in which a predetermined portion is coated with photo resist; and
- the position of the achromatic lens system included in the optical unit is adjusted such that the regular light beam which passed through the optical unit is focused on the light detector.
- the wavelength of the regular light beam is longer than 190 nm and different from that of the vacuum ultraviolet light beam, and therefore, the regular light beam is hard to be absorbed in oxygen and can be transmitted in the air. Accordingly, operation of adjusting the position of the achromatic lens system can be carried out easily in the air.
- the vacuum ultraviolet light beam is to be measured, the inside of the housing is evacuated or purged by using nitrogen gas. Since the achromatic lens system has been already adjusted in the predetermined position, the measurement of the vacuum ultraviolet light beam can be carried out quickly.
- FIG. 1 is a schematic diagram showing general constitution of an instrument for measuring a vacuum ultraviolet light beam according to the first embodiment of the present invention
- FIG. 2 is a flowchart showing a measuring process using the instrument as shown in FIG. 1;
- FIG. 3 is a schematic diagram showing general constitution of an instrument for measuring a vacuum ultraviolet light beam according to the second embodiment of the present invention.
- FIG. 4A is a schematic diagram showing a state of an instrument for measuring a vacuum ultraviolet light beam according to the third embodiment of the present invention before adjustment;
- FIG. 4B is a schematic diagram showing a state of the measuring instrument according to the third embodiment of the present invention after adjustment
- FIG. 5 is a flowchart of a measuring process using the measuring instrument as shown in FIGS. 4A and 4B.
- FIG. 6A is a schematic diagram showing a state of an instrument for measuring a vacuum ultraviolet light according to the fourth embodiment of the present invention before adjustment;
- FIG. 6B is a schematic diagram showing a state of the measuring instrument according to the fourth embodiment of the present invention after adjustment.
- FIG. 7 is a schematic diagram showing general constitution of an optical exposure apparatus according to an embodiment of the present invention.
- FIG. 1 shows general constitution of an instrument for measuring a vacuum ultraviolet light beam according to the first embodiment of the present invention.
- This instrument is used for measuring, for example, beam-profiling a diffraction pattern of an F 2 (molecular fluorine) laser beam radiated from F 2 laser 20 . Therefore, this instrument will be called as a beam-profiler instrument hereinafter.
- F 2 molecular fluorine
- beam-profiler instrument 10 includes achromatic lens system 12 and CCD sensor 13 which are arranged in purge box 11 .
- Achromatic lens system or achromat includes two or more lenses so as to correct chromatic aberration for selected two wavelengths.
- Achromatic lens system 12 is composed by combining single lens 14 , which is produced from fluorite (CaF 2 ) and has a convex form, with single lens 15 which is produced from fluorine-doped synthetic quartz and has a planoconcave form.
- the fluorine-doped synthetic quartz is a material of glass that has been developed for a light beam having a wavelength range including 157 nm.
- the fluorine-doped synthetic quartz is explained in “Effects of fluorine dimer excimer laser radiation on the optical transmission and defect formation of various types of synthetic SiO 2 glasses” Hosono et. al., APPLIED PHYSICS LETTERS VOL. 74 NO. 19, May 10, 1999 and so forth in detail.
- Fluorite and fluorine-doped synthetic quartz are materials of glass which are different in a dispersion value of a refractive index.
- a form and numerical values of each of single lenses 14 and 15 are designed optimally so as to fulfill achromatic conditions for both an ArSHG laser beam (second harmonic generation argon ion laser beam) having a wavelength of 248.25 nm and an F 2 laser beam having a wavelength of 157.63 nm.
- the ArSHG laser beam and the F 2 laser beam can be focused on the same position. Since a wavelength of the ArSHG laser beam is longer than 190 nm, that is, the ArSHG laser beam does not belong to the vacuum ultraviolet light beam, the ArSHG laser beam is hard to be absorbed in oxygen and can be transmitted in the air.
- CCD sensor 13 is a sort of optical sensors and has plural light detectors, for example, photodiodes arranged in one-dimensional or two-dimensional. Each light detector of CCD sensor 13 outputs an electric signal corresponding to intensity of a detected light beam. In this embodiment, CCD sensor 13 is used for detecting a diffraction pattern of an F 2 laser beam.
- F 2 laser 20 is a light source which generates an F 2 laser beam.
- F 2 laser 20 includes rear mirror 22 , front mirror 23 and medium chamber 24 as central parts, which are enclosed in vacuum chamber 21 .
- a beam diameter of an ArSHG laser beam radiated from ArSHG laser 30 is expanded by beam expander 40 before the ArSHG laser beam is incident into F 2 laser 20 .
- Beam expander 40 includes two convex single lenses 41 and 42 .
- Rear mirror 22 is designed so as to transmit the ArSHG laser beam and totally reflect the F 2 laser beam.
- front mirror 23 is designed so as to transmit the ArSHG laser beam and partially reflect the F 2 laser beam.
- Slit board 25 is set on an output side of front mirror 23 before measurement of a diffraction pattern of the F 2 laser beam. The ArSHG laser beam or the F 2 laser beam that passed through front mirror 23 is diffracted by slit board 25 and incident into purge box 11 .
- a distance between rear mirror 22 and front mirror 23 is determined to be integral times as long as a half of the wavelength of the F 2 laser beam. Accordingly, Fabry-Perot resonator is formed between rear mirror 22 and front mirror 23 . By this resonance structure, it is possible to generate a standing wave of the F 2 laser beam between rear mirror 22 and front mirror 23 .
- medium chamber 24 many pulses of the F 2 laser beam are induced by electric discharge and emitted from laser active medium 26 , for example, compound gas of F 2 and He. Therefore, when the inside of vacuum chamber 21 is evacuated, the pulses of the F 2 laser beam are amplified whenever they pass through laser active medium 26 .
- laser active medium 26 for example, compound gas of F 2 and He. Therefore, when the inside of vacuum chamber 21 is evacuated, the pulses of the F 2 laser beam are amplified whenever they pass through laser active medium 26 .
- FIG. 2 is a flowchart showing the measuring process.
- ArSHG laser 30 is set up and emits an ArSHG laser beam.
- the ArSHG laser beam emitted from ArSHG laser 30 is incident into F 2 laser 20 .
- achromatic lens system 21 and CCD sensor 13 are arranged in purge box 11 .
- a position of achromatic lens system 12 is determined properly.
- air fills purge box 11 .
- step S 13 slit board 25 is set on an output side of front mirror 23 . Therefore, the ArSHG laser beam or the F 2 laser beam that passed through front mirror 23 is diffracted by slit board 25 and incident into purge box 11 . At this time point, the ArSHG laser beam reaches CCD sensor 13 through achromatic lens system 12 .
- step S 14 the position of achromatic lens system 12 is adjusted such that the ArSHG laser beam which passed through achromatic lens system 12 is focused on CCD sensor 13 .
- step S 15 the inside of purge box 11 is purged by using nitrogen gas.
- step S 16 ArSHG laser 30 is turned off and F 2 laser 20 is turned on.
- the F 2 laser beam is focused on CCD sensor 13 through achromatic lens system 12 .
- step S 17 a profile of the diffraction pattern of the F 2 laser beams can be measured by analyzing output signals of CCD sensor 13 .
- a position of achromatic lens system 12 is adjusted such that the ArSHG laser beam which passed through achromatic lens system 12 is focused on CCD sensor 13 .
- a wavelength of the ArSHG laser beam is longer than 190 nm and different from that of the F 2 laser beam. Therefore, the ArSHG laser beam is hard to be absorbed in oxygen and can be transmitted in the air.
- operation of adjusting a position of achromatic lens system 12 can be easily carried out in the air. Since the position of achromatic lens system 12 has been already adjusted when the inside of purge box is purged by using nitrogen gas, measurement of the F 2 laser beam can be quickly carried out.
- FIG. 3 shows general constitution of an instrument for measuring a vacuum ultraviolet light beam according to the second embodiment of the present invention. Since this instrument is used for measuring a beam divergence angle of an F 2 laser beam, this instrument will be called as a beam divergence instrument hereinafter.
- a general laser beam is focused not on a point but on a circular area because it diverges from a parallel light beam by a minute angle.
- a beam divergence angle of an F 2 laser beam radiated from F 2 laser 20 is measured by analyzing a circular image formed on CCD sensor by the F 2 laser beam.
- Beam divergence instrument 50 has the same constitution as that of the instrument as shown in FIG. 1 except that slit board 25 is not arranged on front mirror 23 . On this account, a position of achromatic lens system 12 is adjusted by the same operation as step S 14 in the first embodiment. Therefore, according to this embodiment, it is possible to obtain the same effect as that in the first embodiment.
- FIG. 4A shows a state of an instrument for measuring a vacuum ultraviolet light beam according to this embodiment before adjustment.
- FIG. 4B shows a state of the instrument after adjustment. Since this instrument is used for measuring a spectrum of the F 2 laser beam by spectrum-separating the F 2 laser beam, this instrument will be called as a spectrometer hereinafter.
- spectrometer 60 includes slit board 62 , achromatic lens system 63 , diffraction grating 64 and line sensor 65 as central parts enclosed in vacuum chamber 61 .
- Slit board 62 is a sort of optical elements for diffusing an incident light beam in a predetermined angular range. Slit board 62 is arranged perpendicularly against an optical axis of achromatic lens system 63 . A light beam that passed through slit board 62 is transmitted along the optical axis of achromatic lens system 63 .
- Achromatic lens system 63 is composed by combining single lens 66 , which is produced from fluorite and has a convex form, with single lens 67 which is produced from fluorine-doped synthetic quartz and has a planoconcave form.
- a form and numerical values of each of single lenses 66 and 67 are designed optimally so as to fulfill achromatic conditions for both a light beam having a mercury resonance line (253.65 nm) and an F 2 laser beam having a wavelength of 157.63 nm.
- the light beam having the mercury resonance line and the F 2 laser beam can be focused on the same position. Since the mercury resonance line is longer than 190 nm, the light beam having the mercury resonance line does not belong to the vacuum ultraviolet light beam, and therefore, it is hard to be absorbed in oxygen and can be transmitted in the air.
- Diffraction grating 64 is arranged such that it is rotated slightly from the Littrow arrangement in which an incident angle is the same as an output angle.
- diffraction grating 64 a light beam incident from achromatic lens system 63 can be diffracted into a direction rotated by a slight angle from the incident direction of the light beam.
- Such a large diffraction angle as shown in FIGS. 4A and 4B is realized by, for example, an Echelle grating.
- Line sensor 65 is an optical element that is composed by using one-dimensional image sensors, a photo diode array or the like.
- line sensor 65 has plural channels arranged in one-dimension. Each channel of line sensor 65 outputs a response signal corresponding to intensity of a received light beam. Furthermore, such channels may be arranged in two-dimension so that outputs of channels in plural rows are added together for each column.
- Line sensor 65 is arranged to receive a light beam which has gone and returned twice between achromatic lens system 63 and diffraction grating 64 .
- FIG. 5 is a flowchart showing the measuring process.
- a low-pressure mercury vapor lamp is fixed on vacuum chamber 61 and then set up.
- a light beam having a mercury resonance line radiated from the low-pressure mercury vapor lamp is incident into vacuum chamber 61 .
- achromatic lens system 63 is shifted from one position indicated by a broken line to another position indicated by a solid line in FIG. 4B such that the light beam having the mercury resonance line that passed through achromatic lens system 63 is focused on line sensor 65 .
- a part of the light beam having the mercury resonance line incident into vacuum chamber 61 passes through achromatic lens system 63 , while the rest is reflected from achromatic lens system 63 to slit board 61 .
- the light beam that passed through achromatic lens system 63 is diffracted by diffraction grating 64 to achromatic lens system 63 .
- a part of the diffracted light beam passes through achromatic lens system 63 , while the rest is reflected from achromatic lens system 63 to diffraction grating 64 .
- the light beam incident into diffraction grating 64 again is diffracted toward achromatic lens system 63 one more time, and a part of the diffracted light beam reaches line sensor 65 through achromatic lens system 63 .
- step S 23 the inside of vacuum chamber 61 is evacuated. Further, at step S 24 , the low-pressure mercury vapor lamp is replaced with the F 2 laser, and then, the F 2 laser is set up. By this operation, the F 2 laser beam is incident into vacuum chamber 61 and passes along the same optical path as that of the light beam having the mercury resonance line to be focused on line sensor 65 .
- step S 25 a spectrum of the F 2 laser beam is measured by analyzing the output signals of line sensor 65 .
- a position of achromatic lens system 63 is adjusted such that a mercury resonance light beam, which has gone and returned twice between achromatic lens system 63 and diffraction grating 64 , is focused on line sensor 65 through achromatic lens system 63 . Since the wavelength of the mercury resonance light beam is longer than 190 nm and different from that of the F 2 laser beam, the mercury resonance light beam is hard to be absorbed in oxygen. Further, the low-pressure mercury vapor lamp is inexpensive and radiates the mercury resonance line with stability. Accordingly, operation of adjusting the position of achromatic lens system 63 can be easily carried out in the air. Since the position of achromatic lens system 63 has been already adjusted when the inside of vacuum chamber 61 is evacuated, the measurement of the F 2 laser beam can be quickly carried out.
- FIG. 6A shows a state of an instrument for measuring a vacuum ultraviolet light beam according to this embodiment before adjustment.
- FIG. 6B shows a state of the instrument after adjustment. Since this instrument is used for measuring a spectrum of an F 2 laser beam by spectrum-separating the F 2 laser beam, this instrument will be called as a spectrometer hereinafter.
- spectrometer 70 includes ground glass 71 , etalon 72 , achromatic lens system 63 and line sensor 65 enclosed in vacuum chamber 61 .
- Ground glass 71 is a sort of optical element for scattering an incident light beam into various directions, and is arranged perpendicularly against an optical axis of achromatic lens system 63 . A light beam which passed through ground glass 71 is transmitted along the optical axis of achromatic lens system 63 .
- Etalon 72 is composed by forming partial reflection coating 74 on both sides of optical glass 73 which is produced from, for example, fluorite (CaF 2 ) to have a flat form.
- Fabry-Perot resonator is formed between the two partial reflection coatings. Owing to this resonance structure, interference fringes of the F 2 laser beam having are formed as rings on line sensor 65 when the position of achromatic lens system 63 has been adjusted.
- spectrometer 70 includes achromatic lens system 63 for the light beam having the mercury resonance line and the F 2 laser beam similarly to the third embodiment, the position of achromatic lens system 63 can be adjusted by carrying out by the same operation as step S 22 in the third embodiment. Accordingly, the same effect as that in the third embodiment can be obtained in this embodiment.
- FIG. 7 shows general constitution of the optical exposure apparatus according this embodiment.
- Optical exposure apparatus 80 as shown in FIG. 7 is an apparatus for exposing photo resist coated on a predetermined portion of wafer 90 by using the F 2 laser beam.
- Main components of the optical exposure apparatus 80 are enclosed in vacuum chamber 81 .
- F 2 laser 20 generates and radiates the F 2 laser beam by using an ArSHG laser beam incident from an ArSHG laser.
- Illumination optical unit 82 including an achromatic lens system having the same constitution as that in the first embodiment is arranged on an output side of F 2 laser 20 .
- the F 2 laser beam which passed through mirrors 83 and 84 illuminates photo mask 91 through illumination optical unit 82 .
- Mask stage 85 is arranged on an output side of illumination optical unit 82 and used to fix photo mask 91 in which a desired pattern is formed.
- the F 2 laser beam that passed through photo mask 91 is incident into projection optical unit 86 arranged on an output side of mask stage 85 .
- Projection optical unit 86 includes an achromatic lens system having the same constitution as that in the first embodiment.
- Projection optical unit 86 projects the F 2 laser beam that passed through photo mask 91 on the photo resist coated on wafer 90 .
- Wafer stage 88 is arranged on an output side of projection optical unit 86 and used to fix chuck 87 for absorbing and retaining wafer 90 .
- the F 2 laser beam that passed through photo mask 91 is projected on the photo resist coated on wafer 90 and exposes the photo resist while mask stage 85 and wafer stage 88 are scanned synchronously to the opposite directions. As a result, a pattern in photo mask 91 is transcribed on the photo resist.
- each of illumination optical unit 82 and projection optical unit 86 includes an achromatic lens system having the same constitution as in the first embodiment.
- a position of each achromatic lens system is adjusted such that the ArSHG laser beam that passed through photo mask 91 is focused on the photo resist coated on wafer 91 .
- operation of adjusting the position of each achromatic lens system can be easily carried out in the air. Since the position of each achromatic lens system has been already adjusted when the inside of vacuum chamber 81 is evacuated, the exposure treatment by using the F 2 laser beam can be quickly carried out.
- an achromatic lens system that fulfils achromatic conditions for both a KrF (kripton fluoride) excimer laser beam having a wavelength of 248 nm and the F 2 laser beam may be used. Further, an achromatic lens system that fulfils achromatic conditions for both an ArF (argon fluoride) excimer laser beam having a wavelength of 198 nm and the F 2 laser beam may be used. Furthermore, an achromatic lens system including a plurality of lenses except for a combination of a convex lens and a concave lens may be used.
- a position of an achromatic lens system included in an optical unit can be easily carried out in the air.
- the inside of the housing is evacuated or purged by using nitrogen gas. Since the achromatic lens system has been already adjusted in the predetermined position, the measurement of the vacuum ultraviolet light beam can be carried out quickly. Similarly, exposure treatment by using the vacuum ultraviolet light beam can be carried out quickly.
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Abstract
A method and instrument for measuring a vacuum ultraviolet light beam in which a position of an optical unit used for measuring a vacuum ultraviolet light beam can be adjusted easily and measurement of the vacuum ultraviolet light beam is carried out quickly. This method includes a first step of passing a ArSHG laser beam through an achromatic lens system; a second step of adjusting a position of the achromatic lens system such that the ArSHG laser beam which passed through the achromatic lens system is focused on a CCD sensor; a third step of purging the inside of a purge box by using nitrogen gas; and a fourth step of focusing an F2 laser beam which passed through the achromatic lens system on the CCD sensor so as to measure the F2 laser beam.
Description
- 1. Field of the Invention
- The present invention relates to a method and an instrument for measuring a vacuum ultraviolet light beam having a wavelength not longer than 190 nm. Further, the present invention relates to a method for producing a device which method includes exposure treatment using the vacuum ultraviolet light beam and an optical exposure apparatus.
- 2. Description of a Related Art
- In an optical exposure apparatus, a micro-fabrication of a pattern to be transcribed on photo resist, which is coated on a predetermined portion of a substrate, is going on more than ever before, and more improvement of resolution of an optical exposure apparatus is demanded. As a solution for responding to this demand, it is promoted to shorten a wavelength of a light beam for exposure treatment. At the present time, the usable light source that can output a light beam having the shortest wavelength is an F2 (molecular fluorine) laser. The F2 laser beam is a sort of vacuum ultraviolet light beam having a wavelength not longer than 190 nm. And an oscillated wavelength of the F2 laser beam is 157.63 nm, and an oscillated spectral width of the F2 laser beam is not longer than a few pico-meters.
- From the above reason, in recent years, an optical exposure apparatus using the F2 laser, which will be called as an F2 laser beam exposure system hereinafter, as a light source for exposure is provided. Also, an instrument for measuring the F2 laser beam, which will be called as an F2 laser beam measuring instrument hereinafter, is provided. An optical unit of each of those instruments includes a fluoride lens. The fluoride lens is a single lens composed from fluorite (CaF2), which is suited for the F2 laser beam. The F2 laser beam tends to be easily absorbed into oxygen. On this account, while the F2 laser beam is transmitted, an inside of a housing enclosing a light detector, an optical unit and so on is evacuated or purged by using nitrogen gas. Nitrogen purge is an operation of removing oxygen gas by using dry nitrogen gas.
- By the way, an instrument for measuring a light beam or an optical exposure apparatus should be adjusted such that an optical unit included in the instrument realizes its own aim. This is the same in a conventional F2 laser beam measuring instrument or a conventional F2 laser beam exposure system. However, a focal length of a single lens such as a fluoride lens is different in accordance with a wavelength of a light beam. For example, in the case of a convex fluoride lens having a curvature radius of 90 mm and a diameter of 50 mm, the focal length for a light beam radiated from a low pressure mercury-vapor lamp and having a mercury resonance line (253.65 nm) is 253.65 mm, while the focal length for an F2 laser beam having a wavelength of 157.63 nm is 214.60 mm. On this account, in the conventional F2 laser beam measuring instrument or the conventional F2 laser beam exposure system, other light source except for the F2 laser can not be used for adjustment of an optical unit, for example, adjustment of a position of the fluoride lens.
- Therefore, adjustment of the conventional F2 laser beam measuring instrument or the conventional F2laser beam exposure system is carried out as follows:
- (1) The inside of the housing enclosing a light detector, an optical unit and so on is evacuated or purged by using nitrogen gas.
- (2) An F2 laser beam is transmitted into the inside of the housing which has been evacuated or purged by using nitrogen gas. And the F2 laser beam is focused on the light detector through the optical unit.
- (3) Based upon the result obtained by the F2 laser beam focused on the light detector, adjustment of the optical unit including adjustment of a position of the fluoride lens is carried out.
- Thus, the adjustment of the optical unit including the adjustment of the position of the fluoride lens must be carried out in the housing which has been evacuated or purged by using nitrogen gas. Therefore, operation of the adjustment is very difficult. This increases difficulty of measurement of the F2 laser beam and prevents the spread of exposure treatment using the F2 laser beam.
- In order to solve such a problem, it is proposed that an achromatic lens system designed optimally so as to fulfill achromatic conditions for both an F2 laser beam and another light beam (for example, a mercury resonance line) is substituted for the fluoride lens. In order to produce such an achromatic lens system, at least two materials of glass are required which are different in a dispersion value of a refractive index. However, in the past, fluorite was the only material of glass suited for the F2 laser beam, and therefore, such an achromatic lens system could not be produced.
- The present invention has been accomplished in view of those problems. The first object of the present invention is to provide a method and an instrument for measuring a vacuum ultraviolet light beam wherein a position of an optical unit to be used for measuring the vacuum ultraviolet light beam can be easily adjusted so as to quickly measure the vacuum ultraviolet light beam. Further, the second object of the present invention is to provide a method of producing a device and an optical exposure apparatus wherein a position of each of an illumination optical unit and a projection optical unit to be used for exposure treatment by using a vacuum ultraviolet light beam can be easily adjusted so as to quickly carry out the exposure treatment.
- In order to solve the above-mentioned problem, a method of measuring a vacuum ultraviolet light beam having a wavelength not longer than 190 nm, according to the present invention, comprises: a first step of passing a regular light beam having a wavelength longer than 190 nm through an optical unit; a second step of adjusting a position of an achromatic lens system included in the optical unit such that the regular light beam which passed through the optical unit is focused on a light detector, the achromatic lens system being composed by combining one single lens produced from fluorite with another single lens produced from fluorine-doped synthetic quartz so as to fulfill achromatic conditions for both the regular light beam and the vacuum ultraviolet light beam; a third step of conducting, after the second step, one of (i) evacuating the inside of a housing for enclosing the optical unit and the light detector and (ii) purging the inside of the housing by using nitrogen gas; and a fourth step of focusing, after the third step, the vacuum ultraviolet light beam which passed through the optical unit on the light detector so as to measure the vacuum ultraviolet light beam.
- Further, an instrument for measuring a vacuum ultraviolet light beam having a wavelength not longer than 190 nm, according to the present invention, comprises: a light detector for detecting both a regular light beam having a wavelength longer than 190 nm and the vacuum ultraviolet light beam; an optical unit including an achromatic lens system which is composed by combining one single lens produced from fluorite with another single lens produced from fluorine-doped synthetic quartz so as to fulfill achromatic conditions for both the regular light beam and the vacuum ultraviolet light beam; and a housing for enclosing the optical unit and the light detector in order to conduct one of (i) evacuating the inside of the housing and (ii) purging the inside of the housing by using nitrogen gas when measuring the vacuum ultraviolet light beam.
- Furthermore, a method of producing a device by using an illumination optical unit, a photo mask stage for fixing a photo mask in which a desired pattern is formed, a projection optical unit and a substrate stage for fixing a substrate in which a predetermined portion is coated with photo resist each enclosed in a housing, according to the present invention, comprises: a first step of passing a regular light beam having a wavelength longer than 190 nm through the illumination optical unit, the photo mask and the projection optical unit in this order; a second step of adjusting a position of an achromatic lens system included in each of the illumination optical unit and the projection optical unit such that the regular light beam which passed through the illumination optical unit, the photo mask and the projection optical unit in this order is focused on the photo resist, the achromatic lens system being composed by combining one single lens produced from fluorite with another single lens produced from fluorine-doped synthetic quartz so as to fulfill achromatic conditions for both the regular light beam and the vacuum ultraviolet light beam; a third step of evacuating the inside of the housing after the second step; and a fourth step of focusing, after the third step, the vacuum ultraviolet light beam which passed through the illumination optical unit, the photo mask and the projection optical unit in this order on the photo resist in order to expose the photo resist.
- Moreover, an optical exposure apparatus according to the present invention comprises: an illumination optical unit including an achromatic lens system which is composed by combining one single lens produced from fluorite with another single lens produced from fluorine-doped synthetic quartz so as to fulfill achromatic conditions for both a regular light beam having a wavelength longer than 190 nm and a vacuum ultraviolet light beam having a wavelength not longer than 190 nm; a photo mask stage, arranged on an output side of the illumination optical unit, for fixing a photo mask in which a desired pattern is formed; an projection optical unit arranged on an output side of the photo mask stage, the projection optical unit including an achromatic lens system which is composed by combining one single lens produced from fluorite with another single lens produced from fluorine-doped synthetic quartz so as to fulfill achromatic conditions for both the regular light beam and the vacuum ultraviolet light beam; a substrate stage, arranged on an output side of the projection optical unit, for fixing a substrate in which a predetermined portion is coated with photo resist; and a housing for enclosing the illumination optical unit, the photo mask stage, the projection optical unit and the substrate stage in order to evacuate the inside of the housing when exposing the photo resist by using the vacuum ultraviolet light beam.
- According to the present invention, the position of the achromatic lens system included in the optical unit is adjusted such that the regular light beam which passed through the optical unit is focused on the light detector. The wavelength of the regular light beam is longer than 190 nm and different from that of the vacuum ultraviolet light beam, and therefore, the regular light beam is hard to be absorbed in oxygen and can be transmitted in the air. Accordingly, operation of adjusting the position of the achromatic lens system can be carried out easily in the air. When the vacuum ultraviolet light beam is to be measured, the inside of the housing is evacuated or purged by using nitrogen gas. Since the achromatic lens system has been already adjusted in the predetermined position, the measurement of the vacuum ultraviolet light beam can be carried out quickly.
- The present invention will be described in more detail in conjunction with the appended drawings, wherein:
- FIG. 1 is a schematic diagram showing general constitution of an instrument for measuring a vacuum ultraviolet light beam according to the first embodiment of the present invention;
- FIG. 2 is a flowchart showing a measuring process using the instrument as shown in FIG. 1;
- FIG. 3 is a schematic diagram showing general constitution of an instrument for measuring a vacuum ultraviolet light beam according to the second embodiment of the present invention;
- FIG. 4A is a schematic diagram showing a state of an instrument for measuring a vacuum ultraviolet light beam according to the third embodiment of the present invention before adjustment;
- FIG. 4B is a schematic diagram showing a state of the measuring instrument according to the third embodiment of the present invention after adjustment;
- FIG. 5 is a flowchart of a measuring process using the measuring instrument as shown in FIGS. 4A and 4B.
- FIG. 6A is a schematic diagram showing a state of an instrument for measuring a vacuum ultraviolet light according to the fourth embodiment of the present invention before adjustment;
- FIG. 6B is a schematic diagram showing a state of the measuring instrument according to the fourth embodiment of the present invention after adjustment; and
- FIG. 7 is a schematic diagram showing general constitution of an optical exposure apparatus according to an embodiment of the present invention.
- Referring to attached drawings, embodiments of the present invention will be explained as follows. In the embodiments, since the same reference numeral is used for the common element, the explanation of the common element will be omitted.
- At first, referring to FIGS. 1 and 2, the first embodiment of the present invention will be explained. FIG. 1 shows general constitution of an instrument for measuring a vacuum ultraviolet light beam according to the first embodiment of the present invention. This instrument is used for measuring, for example, beam-profiling a diffraction pattern of an F2 (molecular fluorine) laser beam radiated from F2 laser 20. Therefore, this instrument will be called as a beam-profiler instrument hereinafter.
- As shown in FIG. 1, beam-
profiler instrument 10 includesachromatic lens system 12 andCCD sensor 13 which are arranged inpurge box 11. - Achromatic lens system or achromat includes two or more lenses so as to correct chromatic aberration for selected two wavelengths.
Achromatic lens system 12 is composed by combiningsingle lens 14, which is produced from fluorite (CaF2) and has a convex form, withsingle lens 15 which is produced from fluorine-doped synthetic quartz and has a planoconcave form. The fluorine-doped synthetic quartz is a material of glass that has been developed for a light beam having a wavelength range including 157 nm. The fluorine-doped synthetic quartz is explained in “Effects of fluorine dimer excimer laser radiation on the optical transmission and defect formation of various types of synthetic SiO2 glasses” Hosono et. al., APPLIED PHYSICS LETTERS VOL. 74 NO. 19, May 10, 1999 and so forth in detail. - Fluorite and fluorine-doped synthetic quartz are materials of glass which are different in a dispersion value of a refractive index. On this account, in this embodiment, a form and numerical values of each of
single lenses achromatic lens system 12, the ArSHG laser beam and the F2 laser beam can be focused on the same position. Since a wavelength of the ArSHG laser beam is longer than 190 nm, that is, the ArSHG laser beam does not belong to the vacuum ultraviolet light beam, the ArSHG laser beam is hard to be absorbed in oxygen and can be transmitted in the air. -
CCD sensor 13 is a sort of optical sensors and has plural light detectors, for example, photodiodes arranged in one-dimensional or two-dimensional. Each light detector ofCCD sensor 13 outputs an electric signal corresponding to intensity of a detected light beam. In this embodiment,CCD sensor 13 is used for detecting a diffraction pattern of an F2 laser beam. - F2 laser 20 is a light source which generates an F2 laser beam. F2 laser 20 includes
rear mirror 22,front mirror 23 andmedium chamber 24 as central parts, which are enclosed invacuum chamber 21. - In this embodiment, a beam diameter of an ArSHG laser beam radiated from
ArSHG laser 30 is expanded bybeam expander 40 before the ArSHG laser beam is incident into F2 laser 20.Beam expander 40 includes two convexsingle lenses -
Rear mirror 22 is designed so as to transmit the ArSHG laser beam and totally reflect the F2 laser beam. On the other hand,front mirror 23 is designed so as to transmit the ArSHG laser beam and partially reflect the F2 laser beam.Slit board 25 is set on an output side offront mirror 23 before measurement of a diffraction pattern of the F2 laser beam. The ArSHG laser beam or the F2 laser beam that passed throughfront mirror 23 is diffracted byslit board 25 and incident intopurge box 11. - Therefore, in the case where the inside of
purge box 11 is not purged, the ArSHG laser beam reachesCCD sensor 13 throughachromatic lens system 12, while the F2 laser beam is absorbed in oxygen included inpurge box 11. On the other hand, in the case where the inside ofpurge box 11 is purged by using nitrogen gas, both the ArSHG laser beam and the F2 laser beam can reachCCD sensor 13 throughachromatic lens system 12. - A distance between
rear mirror 22 andfront mirror 23 is determined to be integral times as long as a half of the wavelength of the F2 laser beam. Accordingly, Fabry-Perot resonator is formed betweenrear mirror 22 andfront mirror 23. By this resonance structure, it is possible to generate a standing wave of the F2 laser beam betweenrear mirror 22 andfront mirror 23. - In
medium chamber 24, many pulses of the F2 laser beam are induced by electric discharge and emitted from laseractive medium 26, for example, compound gas of F2 and He. Therefore, when the inside ofvacuum chamber 21 is evacuated, the pulses of the F2 laser beam are amplified whenever they pass through laseractive medium 26. - Next, referring to FIG. 2, a measuring process by using beam-
profiler instrument 10 will be explained. FIG. 2 is a flowchart showing the measuring process. - At first, at step S11,
ArSHG laser 30 is set up and emits an ArSHG laser beam. The ArSHG laser beam emitted fromArSHG laser 30 is incident into F2 laser 20. - Next, at step S12,
achromatic lens system 21 andCCD sensor 13 are arranged inpurge box 11. A position ofachromatic lens system 12 is determined properly. At this time point, air fillspurge box 11. - Further, at step S13, slit
board 25 is set on an output side offront mirror 23. Therefore, the ArSHG laser beam or the F2 laser beam that passed throughfront mirror 23 is diffracted byslit board 25 and incident intopurge box 11. At this time point, the ArSHG laser beam reachesCCD sensor 13 throughachromatic lens system 12. - Further, at step S14, the position of
achromatic lens system 12 is adjusted such that the ArSHG laser beam which passed throughachromatic lens system 12 is focused onCCD sensor 13. - Next, at step S15, the inside of
purge box 11 is purged by using nitrogen gas. Then, at step S16,ArSHG laser 30 is turned off and F2 laser 20 is turned on. As a result, the F2 laser beam is focused onCCD sensor 13 throughachromatic lens system 12. At step S17, a profile of the diffraction pattern of the F2laser beams can be measured by analyzing output signals ofCCD sensor 13. - According to this embodiment, a position of
achromatic lens system 12 is adjusted such that the ArSHG laser beam which passed throughachromatic lens system 12 is focused onCCD sensor 13. A wavelength of the ArSHG laser beam is longer than 190 nm and different from that of the F2 laser beam. Therefore, the ArSHG laser beam is hard to be absorbed in oxygen and can be transmitted in the air. On this account, operation of adjusting a position ofachromatic lens system 12 can be easily carried out in the air. Since the position ofachromatic lens system 12 has been already adjusted when the inside of purge box is purged by using nitrogen gas, measurement of the F2 laser beam can be quickly carried out. - Next, referring to FIG. 3, the second embodiment of the present invention will be explained. FIG. 3 shows general constitution of an instrument for measuring a vacuum ultraviolet light beam according to the second embodiment of the present invention. Since this instrument is used for measuring a beam divergence angle of an F2 laser beam, this instrument will be called as a beam divergence instrument hereinafter.
- A general laser beam is focused not on a point but on a circular area because it diverges from a parallel light beam by a minute angle. In this view, according to this embodiment, a beam divergence angle of an F2 laser beam radiated from F2 laser 20 is measured by analyzing a circular image formed on CCD sensor by the F2 laser beam.
-
Beam divergence instrument 50 has the same constitution as that of the instrument as shown in FIG. 1 except that slitboard 25 is not arranged onfront mirror 23. On this account, a position ofachromatic lens system 12 is adjusted by the same operation as step S14 in the first embodiment. Therefore, according to this embodiment, it is possible to obtain the same effect as that in the first embodiment. - Next, referring to FIGS. 4A, 4B and5, the third embodiment of the present invention will be explained. FIG. 4A shows a state of an instrument for measuring a vacuum ultraviolet light beam according to this embodiment before adjustment. FIG. 4B shows a state of the instrument after adjustment. Since this instrument is used for measuring a spectrum of the F2 laser beam by spectrum-separating the F2 laser beam, this instrument will be called as a spectrometer hereinafter.
- As shown in FIGS. 4A and 4B,
spectrometer 60 includes slitboard 62,achromatic lens system 63,diffraction grating 64 andline sensor 65 as central parts enclosed invacuum chamber 61. -
Slit board 62 is a sort of optical elements for diffusing an incident light beam in a predetermined angular range.Slit board 62 is arranged perpendicularly against an optical axis ofachromatic lens system 63. A light beam that passed throughslit board 62 is transmitted along the optical axis ofachromatic lens system 63. -
Achromatic lens system 63 is composed by combiningsingle lens 66, which is produced from fluorite and has a convex form, withsingle lens 67 which is produced from fluorine-doped synthetic quartz and has a planoconcave form. In this embodiment, a form and numerical values of each ofsingle lenses achromatic lens system 63, the light beam having the mercury resonance line and the F2 laser beam can be focused on the same position. Since the mercury resonance line is longer than 190 nm, the light beam having the mercury resonance line does not belong to the vacuum ultraviolet light beam, and therefore, it is hard to be absorbed in oxygen and can be transmitted in the air. -
Diffraction grating 64 is arranged such that it is rotated slightly from the Littrow arrangement in which an incident angle is the same as an output angle. By usingdiffraction grating 64, a light beam incident fromachromatic lens system 63 can be diffracted into a direction rotated by a slight angle from the incident direction of the light beam. Such a large diffraction angle as shown in FIGS. 4A and 4B is realized by, for example, an Echelle grating. -
Line sensor 65 is an optical element that is composed by using one-dimensional image sensors, a photo diode array or the like. In detail,line sensor 65 has plural channels arranged in one-dimension. Each channel ofline sensor 65 outputs a response signal corresponding to intensity of a received light beam. Furthermore, such channels may be arranged in two-dimension so that outputs of channels in plural rows are added together for each column.Line sensor 65 is arranged to receive a light beam which has gone and returned twice betweenachromatic lens system 63 anddiffraction grating 64. - Next, referring to FIG. 5, a measuring
process using spectrometer 60 will be explained. FIG. 5 is a flowchart showing the measuring process. - First, at step S21, a low-pressure mercury vapor lamp is fixed on
vacuum chamber 61 and then set up. Thus, a light beam having a mercury resonance line radiated from the low-pressure mercury vapor lamp is incident intovacuum chamber 61. - Next, at step S22,
achromatic lens system 63 is shifted from one position indicated by a broken line to another position indicated by a solid line in FIG. 4B such that the light beam having the mercury resonance line that passed throughachromatic lens system 63 is focused online sensor 65. - In this state, a part of the light beam having the mercury resonance line incident into
vacuum chamber 61 passes throughachromatic lens system 63, while the rest is reflected fromachromatic lens system 63 to slitboard 61. The light beam that passed throughachromatic lens system 63 is diffracted bydiffraction grating 64 toachromatic lens system 63. A part of the diffracted light beam passes throughachromatic lens system 63, while the rest is reflected fromachromatic lens system 63 todiffraction grating 64. The light beam incident intodiffraction grating 64 again is diffracted towardachromatic lens system 63 one more time, and a part of the diffracted light beam reachesline sensor 65 throughachromatic lens system 63. - Next, at step S23, the inside of
vacuum chamber 61 is evacuated. Further, at step S24, the low-pressure mercury vapor lamp is replaced with the F2 laser, and then, the F2 laser is set up. By this operation, the F2 laser beam is incident intovacuum chamber 61 and passes along the same optical path as that of the light beam having the mercury resonance line to be focused online sensor 65. - Furthermore, at
step S 25, a spectrum of the F2 laser beam is measured by analyzing the output signals ofline sensor 65. - According to this embodiment, a position of
achromatic lens system 63 is adjusted such that a mercury resonance light beam, which has gone and returned twice betweenachromatic lens system 63 anddiffraction grating 64, is focused online sensor 65 throughachromatic lens system 63. Since the wavelength of the mercury resonance light beam is longer than 190 nm and different from that of the F2 laser beam, the mercury resonance light beam is hard to be absorbed in oxygen. Further, the low-pressure mercury vapor lamp is inexpensive and radiates the mercury resonance line with stability. Accordingly, operation of adjusting the position ofachromatic lens system 63 can be easily carried out in the air. Since the position ofachromatic lens system 63 has been already adjusted when the inside ofvacuum chamber 61 is evacuated, the measurement of the F2 laser beam can be quickly carried out. - Next, referring to FIGS. 6A and 6B, the fourth embodiment of the present invention will be explained. FIG. 6A shows a state of an instrument for measuring a vacuum ultraviolet light beam according to this embodiment before adjustment. FIG. 6B shows a state of the instrument after adjustment. Since this instrument is used for measuring a spectrum of an F2 laser beam by spectrum-separating the F2 laser beam, this instrument will be called as a spectrometer hereinafter.
- As shown in FIG. 6,
spectrometer 70 includesground glass 71,etalon 72,achromatic lens system 63 andline sensor 65 enclosed invacuum chamber 61. -
Ground glass 71 is a sort of optical element for scattering an incident light beam into various directions, and is arranged perpendicularly against an optical axis ofachromatic lens system 63. A light beam which passed throughground glass 71 is transmitted along the optical axis ofachromatic lens system 63. -
Etalon 72 is composed by formingpartial reflection coating 74 on both sides ofoptical glass 73 which is produced from, for example, fluorite (CaF2) to have a flat form. Fabry-Perot resonator is formed between the two partial reflection coatings. Owing to this resonance structure, interference fringes of the F2 laser beam having are formed as rings online sensor 65 when the position ofachromatic lens system 63 has been adjusted. - Since
spectrometer 70 includesachromatic lens system 63 for the light beam having the mercury resonance line and the F2 laser beam similarly to the third embodiment, the position ofachromatic lens system 63 can be adjusted by carrying out by the same operation as step S22 in the third embodiment. Accordingly, the same effect as that in the third embodiment can be obtained in this embodiment. - Next, referring to FIG. 7, an optical exposure apparatus according to an embodiment of the present invention will be explained. FIG. 7 shows general constitution of the optical exposure apparatus according this embodiment.
-
Optical exposure apparatus 80 as shown in FIG. 7 is an apparatus for exposing photo resist coated on a predetermined portion ofwafer 90 by using the F2 laser beam. Main components of theoptical exposure apparatus 80 are enclosed invacuum chamber 81. Inchamber 81, F2 laser 20 generates and radiates the F2 laser beam by using an ArSHG laser beam incident from an ArSHG laser. - Illumination
optical unit 82 including an achromatic lens system having the same constitution as that in the first embodiment is arranged on an output side of F2 laser 20. The F2 laser beam which passed throughmirrors illuminates photo mask 91 through illuminationoptical unit 82. -
Mask stage 85 is arranged on an output side of illuminationoptical unit 82 and used to fixphoto mask 91 in which a desired pattern is formed. The F2 laser beam that passed throughphoto mask 91 is incident into projectionoptical unit 86 arranged on an output side ofmask stage 85. Projectionoptical unit 86 includes an achromatic lens system having the same constitution as that in the first embodiment. Projectionoptical unit 86 projects the F2 laser beam that passed throughphoto mask 91 on the photo resist coated onwafer 90. -
Wafer stage 88 is arranged on an output side of projectionoptical unit 86 and used to fixchuck 87 for absorbing and retainingwafer 90. The F2 laser beam that passed throughphoto mask 91 is projected on the photo resist coated onwafer 90 and exposes the photo resist whilemask stage 85 andwafer stage 88 are scanned synchronously to the opposite directions. As a result, a pattern inphoto mask 91 is transcribed on the photo resist. - In this embodiment, each of illumination
optical unit 82 and projectionoptical unit 86 includes an achromatic lens system having the same constitution as in the first embodiment. A position of each achromatic lens system is adjusted such that the ArSHG laser beam that passed throughphoto mask 91 is focused on the photo resist coated onwafer 91. Thus, operation of adjusting the position of each achromatic lens system can be easily carried out in the air. Since the position of each achromatic lens system has been already adjusted when the inside ofvacuum chamber 81 is evacuated, the exposure treatment by using the F2 laser beam can be quickly carried out. - In the above-mentioned embodiments, an achromatic lens system that fulfils achromatic conditions for both a KrF (kripton fluoride) excimer laser beam having a wavelength of 248 nm and the F2 laser beam may be used. Further, an achromatic lens system that fulfils achromatic conditions for both an ArF (argon fluoride) excimer laser beam having a wavelength of 198 nm and the F2 laser beam may be used. Furthermore, an achromatic lens system including a plurality of lenses except for a combination of a convex lens and a concave lens may be used.
- As explained above, according to the present invention, adjustment of a position of an achromatic lens system included in an optical unit can be easily carried out in the air. When a vacuum ultraviolet light beam is to be measured, the inside of the housing is evacuated or purged by using nitrogen gas. Since the achromatic lens system has been already adjusted in the predetermined position, the measurement of the vacuum ultraviolet light beam can be carried out quickly. Similarly, exposure treatment by using the vacuum ultraviolet light beam can be carried out quickly.
Claims (4)
1. A method of measuring a vacuum ultraviolet light beam having a wavelength not longer than 190 nm, said method comprising:
a first step of passing a regular light beam having a wavelength longer than 190 nm through an optical unit;
a second step of adjusting a position of an achromatic lens system included in said optical unit such that the regular light beam which passed through said optical unit is focused on a light detector, said achromatic lens system being composed by combining one single lens produced from fluorite with another single lens produced from fluorine-doped synthetic quartz so as to fulfill achromatic conditions for both the regular light beam and the vacuum ultraviolet light beam;
a third step of conducting, after the second step, one of (i) evacuating the inside of a housing for enclosing said optical unit and said light detector and (ii) purging the inside of said housing by using nitrogen gas; and
a fourth step of focusing, after the third step, the vacuum ultraviolet light beam which passed through said optical unit on said light detector so as to measure the vacuum ultraviolet light beam.
2. An instrument for measuring a vacuum ultraviolet light beam having a wavelength not longer than 190 nm, said instrument comprising:
a light detector for detecting both a regular light beam having a wavelength longer than 190 nm and the vacuum ultraviolet light beam;
an optical unit including an achromatic lens system which is composed by combining one single lens produced from fluorite with another single lens produced from fluorine-doped synthetic quartz so as to fulfill achromatic conditions for both the regular light beam and the vacuum ultraviolet light beam; and
a housing for enclosing said optical unit and said light detector in order to conduct one of (i) evacuating the inside of said housing and (ii) purging the inside of said housing by using nitrogen gas when measuring the vacuum ultraviolet light beam.
3. A method of producing a device by using an illumination optical unit, a photo mask stage for fixing a photo mask in which a desired pattern is formed, a projection optical unit and a substrate stage for fixing a substrate in which a predetermined portion is coated with photo resist, each enclosed in a housing, said method comprising:
a first step of passing a regular light beam having a wavelength longer than 190 nm through said illumination optical unit, said photo mask and said projection optical unit in this order;
a second step of adjusting a position of an achromatic lens system included in each of said illumination optical unit and said projection optical unit such that the regular light beam which passed through said illumination optical unit, said photo mask and said projection optical unit in this order is focused on said photo resist, said achromatic lens system being composed by combining one single lens produced from fluorite with another single lens produced from fluorine-doped synthetic quartz so as to fulfill achromatic conditions for both the regular light beam and the vacuum ultraviolet light beam;
a third step of evacuating the inside of said housing after the second step; and
a fourth step of focusing, after the third step, the vacuum ultraviolet light beam which passed through said illumination optical unit, said photo mask and said projection optical unit in this order on said photo resist in order to expose said photo resist.
4. An optical exposure apparatus comprising:
an illumination optical unit including an achromatic lens system which is composed by combining one single lens produced from fluorite with another single lens produced from fluorine-doped synthetic quartz so as to fulfill achromatic conditions for both a regular light beam having a wavelength longer than 190 nm and a vacuum ultraviolet light beam having a wavelength not longer than 190 nm;
a photo mask stage, arranged on an output side of said illumination optical unit, for fixing a photo mask in which a desired pattern is formed;
an projection optical unit arranged on an output side of said photo mask stage, said projection optical unit including an achromatic lens system which is composed by combining one single lens produced from fluorite with another single lens produced from fluorine-doped synthetic quartz so as to fulfill achromatic conditions for both the regular light beam and the vacuum ultraviolet light beam;
a substrate stage, arranged on an output side of said projection optical unit, for fixing a substrate in which a predetermined portion is coated with photo resist; and
a housing for enclosing said illumination optical unit, said photo mask stage, said projection optical unit and said substrate stage in order to evacuate the inside of said housing when exposing the photo resist by using the vacuum ultraviolet light beam.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2000083106A JP2001272273A (en) | 2000-03-24 | 2000-03-24 | Method and apparatus for measuring vacuum-ultraviolet light, method of manufacturing device and optical exposure apparatus |
JP2000-083106 | 2000-03-24 |
Publications (2)
Publication Number | Publication Date |
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US20020021432A1 true US20020021432A1 (en) | 2002-02-21 |
US6456361B1 US6456361B1 (en) | 2002-09-24 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US09/808,049 Expired - Fee Related US6456361B1 (en) | 2000-03-24 | 2001-03-15 | Method and instrument for measuring vacuum ultraviolet light beam, method of producing device and optical exposure apparatus |
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US (1) | US6456361B1 (en) |
JP (1) | JP2001272273A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8804109B2 (en) * | 2007-04-13 | 2014-08-12 | Hitachi High-Technologies Corporation | Defect inspection system |
US9188544B2 (en) | 2012-04-04 | 2015-11-17 | Kla-Tencor Corporation | Protective fluorine-doped silicon oxide film for optical components |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1397651B1 (en) * | 2001-06-18 | 2007-06-06 | Hinds Instruments, Inc. | Birefringence measurement at deep-ultraviolet wavelengths |
US7016039B2 (en) * | 2003-02-10 | 2006-03-21 | Hinds Instruments, Inc. | Purging light beam paths in optical equipment |
JP2004245905A (en) * | 2003-02-10 | 2004-09-02 | Tadahiro Omi | Mask fabricating device |
-
2000
- 2000-03-24 JP JP2000083106A patent/JP2001272273A/en not_active Withdrawn
-
2001
- 2001-03-15 US US09/808,049 patent/US6456361B1/en not_active Expired - Fee Related
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8804109B2 (en) * | 2007-04-13 | 2014-08-12 | Hitachi High-Technologies Corporation | Defect inspection system |
US9188544B2 (en) | 2012-04-04 | 2015-11-17 | Kla-Tencor Corporation | Protective fluorine-doped silicon oxide film for optical components |
Also Published As
Publication number | Publication date |
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US6456361B1 (en) | 2002-09-24 |
JP2001272273A (en) | 2001-10-05 |
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