US20020159142A1 - Illuminating apparatus - Google Patents
Illuminating apparatus Download PDFInfo
- Publication number
- US20020159142A1 US20020159142A1 US10/139,362 US13936202A US2002159142A1 US 20020159142 A1 US20020159142 A1 US 20020159142A1 US 13936202 A US13936202 A US 13936202A US 2002159142 A1 US2002159142 A1 US 2002159142A1
- Authority
- US
- United States
- Prior art keywords
- light
- light source
- wavelength
- illuminating
- optical member
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 230000003287 optical effect Effects 0.000 claims abstract description 55
- 239000011521 glass Substances 0.000 claims abstract description 20
- 239000002178 crystalline material Substances 0.000 claims abstract description 7
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 15
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 claims description 14
- 229910052921 ammonium sulfate Inorganic materials 0.000 claims description 14
- 235000011130 ammonium sulphate Nutrition 0.000 claims description 12
- 229910052782 aluminium Inorganic materials 0.000 claims description 9
- 239000000758 substrate Substances 0.000 claims description 9
- 229910052792 caesium Inorganic materials 0.000 claims description 8
- 239000012535 impurity Substances 0.000 claims description 8
- 229910052701 rubidium Inorganic materials 0.000 claims description 8
- 230000015572 biosynthetic process Effects 0.000 claims description 6
- TVFDJXOCXUVLDH-UHFFFAOYSA-N caesium atom Chemical compound [Cs] TVFDJXOCXUVLDH-UHFFFAOYSA-N 0.000 claims description 6
- IGLNJRXAVVLDKE-UHFFFAOYSA-N rubidium atom Chemical compound [Rb] IGLNJRXAVVLDKE-UHFFFAOYSA-N 0.000 claims description 6
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 5
- 229910052708 sodium Inorganic materials 0.000 claims description 5
- 238000005286 illumination Methods 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 239000012530 fluid Substances 0.000 claims description 3
- 239000010436 fluorite Substances 0.000 claims description 3
- ORUIBWPALBXDOA-UHFFFAOYSA-L magnesium fluoride Chemical compound [F-].[F-].[Mg+2] ORUIBWPALBXDOA-UHFFFAOYSA-L 0.000 claims description 2
- 230000001747 exhibiting effect Effects 0.000 claims 2
- 229910052751 metal Inorganic materials 0.000 abstract description 3
- 239000002184 metal Substances 0.000 abstract description 3
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 37
- 229910052753 mercury Inorganic materials 0.000 description 37
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 27
- 239000007789 gas Substances 0.000 description 19
- 239000000463 material Substances 0.000 description 19
- 238000010521 absorption reaction Methods 0.000 description 16
- 238000000034 method Methods 0.000 description 11
- 239000000126 substance Substances 0.000 description 11
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 10
- AKEJUJNQAAGONA-UHFFFAOYSA-N sulfur trioxide Chemical compound O=S(=O)=O AKEJUJNQAAGONA-UHFFFAOYSA-N 0.000 description 10
- 238000010276 construction Methods 0.000 description 9
- 239000000843 powder Substances 0.000 description 9
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 7
- 229910052760 oxygen Inorganic materials 0.000 description 7
- 239000001301 oxygen Substances 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
- 238000002834 transmittance Methods 0.000 description 6
- 239000004065 semiconductor Substances 0.000 description 5
- 239000011734 sodium Substances 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 239000003989 dielectric material Substances 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 4
- 238000001228 spectrum Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 3
- 229910021529 ammonia Inorganic materials 0.000 description 3
- 238000000295 emission spectrum Methods 0.000 description 3
- 230000031700 light absorption Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000006552 photochemical reaction Methods 0.000 description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- GNKTZDSRQHMHLZ-UHFFFAOYSA-N [Si].[Si].[Si].[Ti].[Ti].[Ti].[Ti].[Ti] Chemical compound [Si].[Si].[Si].[Ti].[Ti].[Ti].[Ti].[Ti] GNKTZDSRQHMHLZ-UHFFFAOYSA-N 0.000 description 2
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 2
- 239000000908 ammonium hydroxide Substances 0.000 description 2
- JEGUKCSWCFPDGT-UHFFFAOYSA-N h2o hydrate Chemical compound O.O JEGUKCSWCFPDGT-UHFFFAOYSA-N 0.000 description 2
- 239000011796 hollow space material Substances 0.000 description 2
- 229910001635 magnesium fluoride Inorganic materials 0.000 description 2
- 239000005368 silicate glass Substances 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- 230000010748 Photoabsorption Effects 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 1
- 238000000862 absorption spectrum Methods 0.000 description 1
- 238000004378 air conditioning Methods 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- LFYJSSARVMHQJB-QIXNEVBVSA-N bakuchiol Chemical compound CC(C)=CCC[C@@](C)(C=C)\C=C\C1=CC=C(O)C=C1 LFYJSSARVMHQJB-QIXNEVBVSA-N 0.000 description 1
- 229910001634 calcium fluoride Inorganic materials 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000005357 flat glass Substances 0.000 description 1
- CJNBYAVZURUTKZ-UHFFFAOYSA-N hafnium(IV) oxide Inorganic materials O=[Hf]=O CJNBYAVZURUTKZ-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000005304 optical glass Substances 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- HYXGAEYDKFCVMU-UHFFFAOYSA-N scandium(III) oxide Inorganic materials O=[Sc]O[Sc]=O HYXGAEYDKFCVMU-UHFFFAOYSA-N 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 238000009827 uniform distribution Methods 0.000 description 1
- RUDFQVOCFDJEEF-UHFFFAOYSA-N yttrium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Y+3].[Y+3] RUDFQVOCFDJEEF-UHFFFAOYSA-N 0.000 description 1
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
- G03F7/70016—Production of exposure light, i.e. light sources by discharge lamps
-
- 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
- G03F7/70916—Pollution mitigation, i.e. mitigating effect of contamination or debris, e.g. foil traps
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/30—Vessels; Containers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/30—Vessels; Containers
- H01J61/302—Vessels; Containers characterised by the material of the vessel
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/38—Devices for influencing the colour or wavelength of the light
- H01J61/40—Devices for influencing the colour or wavelength of the light by light filters; by coloured coatings in or on the envelope
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/84—Lamps with discharge constricted by high pressure
- H01J61/86—Lamps with discharge constricted by high pressure with discharge additionally constricted by close spacing of electrodes, e.g. for optical projection
Definitions
- the present invention relates to an illuminating apparatus for illuminating an object with light emitted from a discharge lamp such as a mercury lamp, and so on.
- the illuminating apparatus according to the present invention is preferably applied especially to an illuminating optical system in an exposure apparatus for manufacturing semiconductors.
- Illuminating apparatus for illuminating objects with light emitted from discharge lamps have been used for various purposes in various fields.
- reduce-projection-type exposure apparatus such as steppers, aligners, and so on
- semiconductor elements such as LSIs and liquid crystal display elements according to the photo-lithography technique
- illuminating apparatus which illuminates reticles on which transferring pattern is formed with light of a certain wavelength (i line having a wavelength of 365 nm, g line having a wavelength of 436 nm, and so on) emitted from extra-high pressure mercury lamps.
- resolution R and depth of focus DOF of a projection-type exposure apparatus can be expressed as follows:
- NA is the numerical aperture of the projection optical system
- ⁇ is the wavelength of the exposure light
- k 1 and k 2 are coefficients determined by processes employed. As is understood from these two formulas, finer pattern can be realized either
- the depth of focus DOF varies in proportion to the wavelength ⁇ of exposure light, as is clearly understood from the formula (2). Accordingly, it is more preferable to shorten the exposure wavelength ⁇ in order to improve resolution because sufficiently large depth of focus can be obtained.
- the emission line of a mercury lamp called i-line (having a wavelength of 365 nm) has almost replaced, as the exposure light used in the projection exposure apparatus, the emission line of the mercury lamp called g-line (having a wavelength of 436 nm).
- FIG. 12 shows an example of the conventional illuminating apparatus used in a projection exposure apparatus, in which a mercury lamp is used as the light source, the emission point of the mercury lamp 1 is arranged at a first focal point F 1 inside an ellipsoidal mirror 2 .
- the inner surface of the ellipsoidal mirror 2 on which aluminum or plurality of layers of various dielectric materials are deposited serves as a reflecting surface.
- the light L emitted from the mercury lamp 1 is reflected by the inner surface of the ellipsoidal mirror 2 toward a mirror 3 .
- On the reflecting surface of the mirror 3 also aluminum or plurality of layers of various dielectric materials are deposited.
- the light reflected by the mirror 3 is condensed at a second focal point F 2 of the ellipsoidal mirror 2 .
- a light source image is formed at the second focal point F 2 .
- the size of the optical system is small.
- the inner surface of the ellipsoidal mirror 2 serving as a converging mirror and the reflecting surfaces of the mirrors 3 and 7 are designed to have maximum reflectance values with respect to the wavelength of the exposure light.
- FIG. 13 shows the distribution of the emission spectrum of this extra-high pressure mercury lamp.
- FIG. 14A shows the relation between wavelengths and the reflectance of an aluminum reflecting mirror on which aluminum is deposited to form a reflecting surface.
- FIG. 14B shows the relation between wavelengths and the reflectance of a typical reflecting mirror according to the prior art on which plurality of layers of dielectric materials are deposited to form a reflecting surface.
- FIG. 15 shows the relation between wavelengths and the transmittance of the band-pass filter 5 when i line is the exposure light.
- the pattern of the reticle 9 is illuminated with illuminating light (i line) with a uniform distribution of illuminance. And the image of the pattern is formed on the photosensitive substrate via the projection optical system (not shown in the drawing).
- the present invention was made.
- the object of the present invention is to provide an illuminating apparatus which condenses light emitted from a discharge lamp with a converging mirror and illuminates an object with the light led through optical members, wherein white powder of ammonium sulfate which adheres to the optical members can be reduced without newly adding an effective heat source nor a mechanism for exhausting gaseous impurities.
- an illuminating apparatus comprises;
- optical member 20 is made of glass or crystalline material to which metal is doped.
- Still another illuminating apparatus according to the present invention, with reference to FIGS. 7 and 12, comprises;
- sulfer dioxide SO 2 is activated by energy of ultraviolet rays to be activated sulfur dioxide SO 2 *;
- ultra-high pressure mercury lamp emits little amount of light having a wavelength of 240 nm or shorter wavelengths, and at the same time since the white powder is found only in the optical path down to the entrance plane of the band-pass filter and not from the band-pass filter downward in the optical path, ultra-violet rays having wavelength in a range from 260 nm to 340 nm is thought to be the main factor of the reaction. Accordingly, if ultraviolet rays having said wavelength from 260 nm to 340 nm can be shielded in the vicinity of the mercury lamp, adhesion of ammonium sulfate which hinders illumination efficiency can be reduced.
- FIG. 1A is a cross-sectional view showing the structure of the mercury lamp used in the first embodiment of the illuminating apparatus according to the present invention.
- FIG. 1B is a cross-sectional view showing a modification of the mercury lamp shown in FIG. 1A.
- FIG. 2 is a chart showing the absorption cross section of vaporous rubidium (Rb).
- FIG. 3 is a chart showing the absorption cross section of vaporous caesium (Cs).
- FIG. 4 is a chart showing the absorption cross section of ozone gas (O 3 ) and that of gaseous oxygen (O 2 ).
- FIG. 5 is a cross-sectional view showing the structure of the mercury lamp used in the second embodiment of the illuminating apparatus according to the present invention.
- FIG. 6 is a chart showing transmittance characteristics of glass material LF5W.
- FIG. 7 is a cross-sectional view showing the structure of the mercury lamp used in the third embodiment of the illuminating apparatus according to the present invention.
- FIG. 8 is a cross-sectional view of the multilayered film with which the surface of the substrate is coated.
- FIG. 9 is a chart showing an example of reflectance characteristics of the multilayered film used in the third embodiment.
- FIG. 10 is a schematic view showing the construction of the fourth embodiment of the illuminating apparatus according to the present invention.
- FIG. 11 is a perspective view showing the broken-out section of a box member 20 used in the fourth embodiment.
- FIG. 12 is a schematic view showing the construction of a conventional illuminating apparatus.
- FIG. 13 is a chart showing the emission spectrum distribution of a ultra-high pressure mercury lamp.
- FIG. 14A is a chart showing the reflectance characteristics of a conventional aluminum reflecting mirror.
- FIG. 14B is a chart showing the reflectance characteristics of a typical reflecting mirror coated with a multilayered film of dielectric substances.
- FIG. 15 is a chart showing the transmittance characteristics of a conventional band-pass filter.
- the first embodiment according to the present invention will be described.
- this embodiment of the illuminating apparatus differs from the conventional illuminating apparatus in that the mercury lamp 1 is replaced by a new one having double-bulb structure.
- this double-bulb mercury lamp used in this embodiment will be described.
- FIG. 1A shows the mercury lamp used in this embodiment.
- a tubular inner bulb 11 has a spherical portion in the middle and the open ends one sealed by bases 12 A and 12 B, respectively. Electrodes 13 A and 13 B are inserted through the bases 12 A and 12 B, respectively, into the hollow inside the inner bulb 11 . Also substances necessary for emission of the mercury lamp are filled in the hollow inside the inner bulb 11 . Thus, the inner bulb 11 with other necessary components functions as an ordinary ultra-high pressure mercury lamp.
- a tubular outer bulb 19 also having a spherical portion in the middle surrounds the inner bulb 11 .
- the doughnut-shaped openings at both ends of the outer bulb 14 are sealed by bases 15 A and 15 B, respectively. And a gas which absorbs light having wavelengths in a range from 260 to 340 nm is filled in a space S between the inner bulb 11 and the outer bulb 14 .
- the ultra-high pressure mercury lamp used in the projection exposure apparatus has the emission spectrum distribution shown in FIG. 13.
- the ultra-high pressure mercury lamp has distributions in a wavelength range from 260 to 340 nm, that is, the wavelength range causing adhesion of the white powder (blurring phenomenon).
- the mercury lamp has the double-bulb structure and the gas which absorbs light having wavelength in the range from 260 to 340 nm is filled in the space S between the inner bulb 11 and the outer bulb 14 , as described above. Gases having such proper absorption characteristics include metallic vapour of rubidium, caesium, and so on.
- FIG. 2 shows the absorption cross section spectrum of vaporous rubidium.
- FIG. 3 shows the absorption cross section spectrum of vaporous caesium. As is shown in FIGS. 2 and 3, both vaporous rubidium and vaporous caesium have large absorption cross sections for wavelength of 340 nm and shorter wavelengths.
- the light in said wavelength range causing the blurring phenomenon can be selectively removed from the light emitted from the inner bulb serving as an ultra-high pressure mercury lamp.
- Gaseous ozone has absorption characteristics similar to those of the above metallic vapor.
- the absorption cross section spectrum of gaseous oxygen (O 2 ) and ozone gas (O 3 ) are shown in FIG. 4, in which reference numeral 17 indicates the absorption cross section spectrum of gaseous oxygen and reference numeral 18 indicates that of ozone gas.
- the absorption spectrum of ozone gas (O 3 ) has ideal absorption characteristics for wavelength of or shorter than 340 nm.
- the ozone gas unlike metallic vapor, dissociates to be O and O 2 in photochemical reactions.
- Photochemical reactions of ozone and oxygen occurs as shown in the following (in the following reaction formulas M, which is called a third body any atom, molecule or ion except an oxygen atom, for example, a molecule of oxygen (O 2 ) or nitrogen (N 2 )).
- Ozone O 3 and/or oxygen O 2 filled in the space S shown in FIG. 1A react as described above until the mixture of gases reaches a chemical equilibrium.
- the final density of ozone should be controlled in consideration of all the reaction and the final chemical equilibrium. In short, the final density of ozone after these photochemical reactions settles in a certain range regardless of any initial densities of ozone.
- n concentration of each substance.
- J's dimension is [1/sec], ⁇ N ⁇ ( ⁇ ) ⁇ ⁇ ⁇ [ cm - 1 , sec - 1 , cm - 1 ]
- [0070] is the number of photons passing per second per unit wavelength per unit area
- ⁇ ( ⁇ )[cm ⁇ 2 ] is the photoelectric absorption cross section of a molecule
- ⁇ max is the maximum wavelength of ⁇ in the above reactions.
- reaction rate of each reaction can be obtained from well-known literature.
- Light absorption efficiency can be promoted by increasing pressure of the gas filled in the double-bulb structure shown in FIG. 1A. But temperature rising caused by light absorption must be taken into account. That is, both the inner bulb 11 and the outer bulb 14 have to be made of glass material having a small coefficient of thermal expansion as well as enough strength.
- the gas which absorbs light having wavelength from 260 to 340 nm may be circulated through the space S between the inner bulb 11 and the outer bulb 14 , as shown in FIG. 1B.
- the gas is supplied through a pipe 16 A into the space S by a gas supplier (not shown), wherein conditions of the gas (density, pressure, flow velocity, temperature, and so on) must be well controlled.
- the gas is exhausted through another pipe 16 B to an exhaust system (not shown).
- FIG. 1B When the structure shown in FIG. 1B is adapted, additional systems are required to monitor and control the pressure and the temperature of the gas circulated through the double-bulb structure.
- the systems for monitoring and controlling the pressure and the temperature of metallic vapor are very large. So metallic vapor is preferably filled in the double-bulb structure, as shown in FIG. 1A, when it is desirable to simplify the construction of the whole apparatus.
- ozone gas is usually circulated through the double-bulb structure shown in FIG. 1B. In this case, however, the density of ozone circulated through the double-bulb structure has to be newly calculated. If the time required to reach the equilibrium is much longer than the time during which the gas remains inside the double-bulb structure, the initial density of ozone has to be high. Otherwise, the flow velocity is changed to obtain desirable densities of ozone.
- FIGS. 5 and 6 This embodiment has construction similar to that shown in FIG. 12, wherein an impurity having certain absorption characteristics is doped in the bulb of the mercury lamp 1 .
- an impurity having certain absorption characteristics is doped in the bulb of the mercury lamp 1 .
- FIG. 5 shows the mercury lamp of this embodiment.
- a tubular bulb 19 has a spherical portion in the middle. The openings of the bulb 19 are sealed by bases 12 A and 12 B. Electrodes 13 A and 13 B are inserted in the hollow inside the bulb 19 through the bases 12 A and 12 B, respectively.
- the bulb 19 with other necessary components functions as an ordinary ultra-high pressure mercury lamp.
- An impurity which absorbs light having wavelength of 340 nm and shorter wavelengths is doped in quartz glass, of which the bulb 19 of the lamp 1 is made.
- One of materials which are preferably doped in quartz glass is sodium Na. Sodium Na, however crystallize SiO 2 at high temperatures, which blurs the bulb 19 . Accordingly, the bulb 19 has to be kept at a temperature of 1000° C. or lower.
- Other preferable materials to be doped in quartz glass includes iron Fe, lead Pb, aluminum Al, rubidium Rb, caesium Cs, and so on.
- the bulb 19 can be made of materials on the market.
- ULETM titanium silicate glass manufactured by Corning Co., Commodity No. 7971
- This ULETM titanium silicate glass absorbs light having a wavelength of 300 nm and shorter wavelength, so the lamp can be effectively prevented from being blurred.
- glass material LF5W manufactured by Ohara Co. is useful.
- This glass material LF5W exhibits light transmittance characteristics shown in FIG. 6.
- the transmittance of this material having a thickness of 10 mm for the light having a wavelength 365 nm (i line) is 0.994, from which reflection loss has already subtracted.
- This glass material having said characteristics can satisfy conditions required according to this embodiment.
- This glass material causes solarization when used at low temperatures. In addition, it can not be used at 400° C. or higher temperatures. Accordingly, the bulb 19 has to be controlled in the temperature range from 100° C. to 400° C.
- FIGS. 7, 8 and 9 the third embodiment of the present invention will be described with reference to FIGS. 7, 8 and 9 .
- This embodiment also has construction similar to that shown in FIG. 12, wherein the glass of the mercury lamp 1 is coated with a multilayered film.
- the same members as those of the previous second embodiment are indicated by the same reference numerals and detailed description thereof is omitted.
- First, the structure of the mercury lamp used in this embodiment will be described.
- the mercury lamp of this embodiment shown in FIG. 7 has a bulb 22 made of ordinary glass material.
- the outer surface 22 a of the bulb 22 is coated with a multilayered film 10 , which reflects light having wavelengths in a range 260 to 340 nm and transmit light having wavelength of 350 nm or longer wavelength.
- the multilayered film selectively transmits the light used as exposure light.
- An example of the multilayered film having selectivity with respect to wavelengths is designed as: air / ( ⁇ 8 ⁇ H : ⁇ 4 ⁇ L : ⁇ 8 ⁇ H ) n / substrate ( 5 )
- H is selected from a group including ZrO 2 , Sc 2 O 3 , HfO 2 , Y 2 O 3 , and so on;
- L is selected from a group including SrO 2 , MgF 2 , and so on;
- the wavelength ⁇ is determined to be about 300 nm; and the number of layers n is generally from 8 to 16.
- FIG. 8 shows a cross section of such a multilayered film, wherein the film is formed according to the above design (5) and the number of layers is 10.
- the substrate materials which transmit light having a wavelength of 350 nm or longer wavelengths can be used, including optical glass, quartz glass, fluorite, and so on. When the material employed as the substrate absorbs light having a wavelength 340 nm or shorter wavelengths, such light can be prevented from being transmitted more effectively.
- the glass of the mercury lamp with the multilayered film, blurring of the other optical members in the illuminating apparatus can be reduced.
- FIGS. 10 and 11 The components in FIG. 10 corresponding to those in FIG. 12 are indicated by the same reference numerals, and detailed description thereof is omitted.
- an optical filter which absorbs light having wavelengths from 260 to 340 nm is provided in the optical path of the illuminating optical system.
- FIG. 10 schematically shows the construction of this embodiment.
- a box member 20 is arranged between the ellipsoidal mirror 2 and the mirror 3 .
- the box member has two flat glass surfaces parallel to each other.
- FIG. 11 shows a broken-out section of the box member.
- the box member 20 has a hollow space 21 , which is arranged to coincide with the optical path.
- a gaseous substance which absorbs light having wavelengths from 260 to 340 nm (cf. description of the first embodiment) is filled in the hollow space 21 .
- the box member is arranged preferably in the vicinity of the mercury lamp 1 , as shown FIG. 10.
- the box member 20 reduces adhesion of the white powder on the optical members arranged downstream in the optical path from the box member 20 .
- the glass material of the box member 20 may be the glass material used in the second embodiment, that is, the glass material which absorbs certain undesirable light.
- the box member 20 may be replaced by a plane parallel glass which has absorption characteristics similar to those of the glass materials used in the second embodiment.
- the plane parallel glass provided in the illuminating optical system may be also made of a crystalline material (for example, fluorite CaF 2 , magnesium fluoride, and so on) to which the above-mentioned metal (such as Na, Fe, and so on) is doped.
- This fourth embodiment is useful in case, for example, the double-bulb structure employed in the first embodiment is difficult to manufacture.
- the illuminating apparatus according to the present invention can be applied not only to the projection exposure apparatus as described but also to a proximity-type exposure apparatus and a contact-type exposure apparatus, and further any type of optical apparatus using ultraviolet rays.
- ammonium sulfate is formed from trace sulfur dioxide (SO 2 ) and ammonia (NH 3 ) existing in the ambient atmosphere in which the illuminating apparatus is used. Accordingly, if the illuminating apparatus is installed in a clean room, sulfur dioxide (SO 2 ) and/or ammonia (NH 3 ) may be removed from the air circulated in the clean room by attaching a filtering system for removing sulfur dioxide (SO 2 ) and/or ammonia (NH 3 ) to the air conditioning system. Thus, formation of ammonium sulfate can be reduced.
- the devices of the first to fourth embodiment can be used separately. But if used in combination, these devices can more effectively prevent adhesion of the white powder. Note that the present invention is not limited to the above-mentioned embodiment.
- the present invention includes any construction which concerns the fundamental principles of the present invention.
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Atmospheric Sciences (AREA)
- Health & Medical Sciences (AREA)
- Epidemiology (AREA)
- Public Health (AREA)
- Plasma & Fusion (AREA)
- Environmental & Geological Engineering (AREA)
- Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
- Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
Abstract
An illuminating apparatus is disclosed which comprises a light source, an optical system for condensing light emitted from the light source and illuminating an object with the condensed light, and an optical member which absorbs light having wavelengths from 260 to 340 nm among the light emitted from the light source, wherein the optical member is made of glass or crystalline material to which metal is doped.
Description
- 1. Field of the Invention
- The present invention relates to an illuminating apparatus for illuminating an object with light emitted from a discharge lamp such as a mercury lamp, and so on. The illuminating apparatus according to the present invention is preferably applied especially to an illuminating optical system in an exposure apparatus for manufacturing semiconductors.
- 2. Related Background Art
- Illuminating apparatus for illuminating objects with light emitted from discharge lamps have been used for various purposes in various fields. Among them, reduce-projection-type exposure apparatus (such as steppers, aligners, and so on), in order to manufacture semiconductor elements such as LSIs and liquid crystal display elements according to the photo-lithography technique, illuminating apparatus which illuminates reticles on which transferring pattern is formed with light of a certain wavelength (i line having a wavelength of 365 nm, g line having a wavelength of 436 nm, and so on) emitted from extra-high pressure mercury lamps.
- Much effort is being made in order to transfer much finer pattern on a photosensitive substrate with higher resolution with such a reduce-projection-type exposure apparatus. In general, resolution R and depth of focus DOF of a projection-type exposure apparatus can be expressed as follows:
- R=k 1 ·λ/NA (1)
- DOF=k 2 ·λ/NA 2 (2)
- wherein NA is the numerical aperture of the projection optical system, λ is the wavelength of the exposure light, k1 and k2 are coefficients determined by processes employed. As is understood from these two formulas, finer pattern can be realized either
- (1) by increasing the numeral aperture NA of the projection optical system, or
- (2) by shortening the wavelength λ (exposure wavelength) of exposure light.
- With respect to the former technique (1), projection optical systems with a large numerical aperture from 0.5 to 0.6 have been already realized, which improves resolution. By only increasing the numerical aperture NA of the projection optical system, however, the depth of focus DOF must be reduced in inverse proportion to the square of the numerical aperture NA, as is understood from the formula (2). In typical semiconductor processes in practical use, a wafer which is to be subjected to exposure of a circuit pattern has irreguralities on its surface formed in the previous process. And flatness of the wafer itself inevitably has errors. Accordingly, sufficient depth of focus DOF have to be obtained.
- On the other hand, with respect to the technique (2), the depth of focus DOF varies in proportion to the wavelength λ of exposure light, as is clearly understood from the formula (2). Accordingly, it is more preferable to shorten the exposure wavelength λ in order to improve resolution because sufficiently large depth of focus can be obtained. As a result, the emission line of a mercury lamp called i-line (having a wavelength of 365 nm) has almost replaced, as the exposure light used in the projection exposure apparatus, the emission line of the mercury lamp called g-line (having a wavelength of 436 nm).
- FIG. 12 shows an example of the conventional illuminating apparatus used in a projection exposure apparatus, in which a mercury lamp is used as the light source, the emission point of the
mercury lamp 1 is arranged at a first focal point F1 inside anellipsoidal mirror 2. The inner surface of theellipsoidal mirror 2 on which aluminum or plurality of layers of various dielectric materials are deposited serves as a reflecting surface. The light L emitted from themercury lamp 1 is reflected by the inner surface of theellipsoidal mirror 2 toward amirror 3. On the reflecting surface of themirror 3, also aluminum or plurality of layers of various dielectric materials are deposited. The light reflected by themirror 3 is condensed at a second focal point F2 of theellipsoidal mirror 2. Thus, a light source image is formed at the second focal point F2. - Light diverging from the second focal point F2 is substantially collimated by a
collimator lens 4, and then is incident on a band-pass filter 5 of narrow-band type, which selects light having wavelength in a certain range as illuminating light. The illuminating light is incident on a fly's-eye lens 6, which forms a number of secondary light sources in its rear (reticle side) focal plane. Light beams diverging from these secondary light sources are reflected by a mirror 7, condensed by acondenser lens 8. The pattern forming surface of areticle 9 is illuminated superimposedly with a number of light beams condensed by thecondenser lens 8. Note that aluminum or plurality of layers of various dielectric materials are deposited also on the reflecting surface of the mirror 7. - As the optical path is bent by the
mirrors 3 and 7, the size of the optical system is small. The inner surface of theellipsoidal mirror 2 serving as a converging mirror and the reflecting surfaces of themirrors 3 and 7 are designed to have maximum reflectance values with respect to the wavelength of the exposure light. - As the mercury lamp, an extra-high pressure mercury lamp is used. FIG. 13 shows the distribution of the emission spectrum of this extra-high pressure mercury lamp. FIG. 14A shows the relation between wavelengths and the reflectance of an aluminum reflecting mirror on which aluminum is deposited to form a reflecting surface. FIG. 14B shows the relation between wavelengths and the reflectance of a typical reflecting mirror according to the prior art on which plurality of layers of dielectric materials are deposited to form a reflecting surface. Further, FIG. 15 shows the relation between wavelengths and the transmittance of the band-
pass filter 5 when i line is the exposure light. In the above-mentioned construction, the pattern of thereticle 9 is illuminated with illuminating light (i line) with a uniform distribution of illuminance. And the image of the pattern is formed on the photosensitive substrate via the projection optical system (not shown in the drawing). - When the illuminating apparatus with the above-mentioned construction is used in the ambient atmosphere, white powder adheres to the surfaces of the optical members arranged between the
mercury lamp 1 and the band-pass filter 5, that is, the surfaces of theellipsoidal mirror 2, themirror 3 and thecollimator lens 4, including the entrance plane of the band-pass filter 5. Because of this white powder, the reflectance values and the transmittance of light L of these optical members decrease to reduce the illumination efficiency. Analysis shows that the white powder is ammonium sulfate, (NH4)2SO4 and that materials concerning the formation of ammonium sulfate do not originally exist in the illuminating apparatus but come from the ambient atmosphere. - A method to solve the above problem is disclosed in U.S. Pat. No. 5,207,505. According to this method, said optical members are heated and maintained beyond 120° C. because ammonium sulfate decomposes beyond this temperature. (“Encyclopedia of Chemistry”, Vol. 9, P690, Kyoritsu Pub., 1964) It is rather easy to heat up and maintain the
ellipsoidal mirror 2 at such a high temperature because themercury lamp 1 arranged near theellipsoidal mirror 2 serves as an effective heat source. The other optical members, however, have to be heated by an additional, very effective heat source. As a semiconductor exposure apparatus requires especially strict temperature control, exhaust of heat is very difficult in practical use. - In consideration of the above-mentioned problems, the present invention was made. And the object of the present invention is to provide an illuminating apparatus which condenses light emitted from a discharge lamp with a converging mirror and illuminates an object with the light led through optical members, wherein white powder of ammonium sulfate which adheres to the optical members can be reduced without newly adding an effective heat source nor a mechanism for exhausting gaseous impurities.
- With reference to FIG. 10, an illuminating apparatus according to the present invention comprises;
- (a) a
light source 1; - (b) an optical system consisting of
optical members 2 to 8 for condensing light emitted from thelight source 1 and illuminating anobject 9 with said condensed light; and - (c) an
optical member 20 for absorbing light having wavelengths in a range from 260 to 340 nm among light emitted from thelight source 1, - wherein the
optical member 20 is made of glass or crystalline material to which metal is doped. - Another illuminating apparatus, also with reference to FIG. 10, according to the present invention comprises:
- (a) a
light source 1; - (b) an optical system consisting of
optical members 2 to 8 for condensing light emitted from thelight source 1 and illuminating anobject 9 with said condensed light; and - (c) an
optical member 20 in which a fluid absorbing light having wavelengths in a range from 260 to 340 nm among light emitted from thelight source 1 is filled. - Still another illuminating apparatus according to the present invention, with reference to FIGS. 7 and 12, comprises;
- (a) a lamp having a pair of
electrodes electrodes - (b) an optical system consisting of
optical members 2 to 8 for condensing light emitted from the lamp and illuminating anobject 9 with said condensed light. - Now basic principles of the present invention will be described. The inventors of the present invention carried out a further examination on the formation processes of white powder of ammonium sulfate from trace substances in the atmosphere.
- Trace substances such as sulfur dioxide SO2 (sulfurous acid) and ammonia NH3 together with oxygen O2 and water vapor H2O are common in the clean room in which the semiconductor exposure apparatus is used as well as in the air. It is probable that these substances react with one another with the help of ultraviolet rays having energy hν (h is Planck's constant, and ν is frequency) as follows.
-
- (2) The resultant activated sulfur dioxide SO2* is oxidized to be sulfur trioxide SO3;
- 2SO2*+O2→2SO3.
- (3) The resultant sulfur trioxide SO3 reacts with water H2O to be sulfuric acid;
- SO3+H2O→H2SO4.
- (4) On the other hand, ammonia NH3 reacts with water H2O to be ammonium hydroxide;
- NH3+H2O→NH4OH.
- (5) The sulfuric acid from the process (3) is neutralized with the ammonium hydroxide from the process (4) to form ammonium sulfate;
- H2SO4+2NH4OH→(NH4)2SO4+2H2O.
- The above examination was carried out on the basis of a literature, “Chiba Univ. Environmental Sci. Res. Rep.” Vol. 1, No. 1, pp 165-177.
- The inventors of the present invention took notice of the reaction (1) among the above reactions in order to find a way to inhibit the formation of ammonium sulfate. According to another literature (H. Okabe: “Photochemistry of Small Molecules” P248, Wiley-Inter Science, 1978), sulfur dioxide has the following four absorption bands:
- (1) 105-180 nm
- (2) 180-240 nm
- (3) 260-340 nm
- (4) 340-390 nm
- Since the ultra-high pressure mercury lamp emits little amount of light having a wavelength of 240 nm or shorter wavelengths, and at the same time since the white powder is found only in the optical path down to the entrance plane of the band-pass filter and not from the band-pass filter downward in the optical path, ultra-violet rays having wavelength in a range from 260 nm to 340 nm is thought to be the main factor of the reaction. Accordingly, if ultraviolet rays having said wavelength from 260 nm to 340 nm can be shielded in the vicinity of the mercury lamp, adhesion of ammonium sulfate which hinders illumination efficiency can be reduced.
- FIG. 1A is a cross-sectional view showing the structure of the mercury lamp used in the first embodiment of the illuminating apparatus according to the present invention.
- FIG. 1B is a cross-sectional view showing a modification of the mercury lamp shown in FIG. 1A.
- FIG. 2 is a chart showing the absorption cross section of vaporous rubidium (Rb).
- FIG. 3 is a chart showing the absorption cross section of vaporous caesium (Cs).
- FIG. 4 is a chart showing the absorption cross section of ozone gas (O3) and that of gaseous oxygen (O2).
- FIG. 5 is a cross-sectional view showing the structure of the mercury lamp used in the second embodiment of the illuminating apparatus according to the present invention.
- FIG. 6 is a chart showing transmittance characteristics of glass material LF5W.
- FIG. 7 is a cross-sectional view showing the structure of the mercury lamp used in the third embodiment of the illuminating apparatus according to the present invention.
- FIG. 8 is a cross-sectional view of the multilayered film with which the surface of the substrate is coated.
- FIG. 9 is a chart showing an example of reflectance characteristics of the multilayered film used in the third embodiment.
- FIG. 10 is a schematic view showing the construction of the fourth embodiment of the illuminating apparatus according to the present invention.
- FIG. 11 is a perspective view showing the broken-out section of a
box member 20 used in the fourth embodiment. - FIG. 12 is a schematic view showing the construction of a conventional illuminating apparatus.
- FIG. 13 is a chart showing the emission spectrum distribution of a ultra-high pressure mercury lamp.
- FIG. 14A is a chart showing the reflectance characteristics of a conventional aluminum reflecting mirror.
- FIG. 14B is a chart showing the reflectance characteristics of a typical reflecting mirror coated with a multilayered film of dielectric substances.
- FIG. 15 is a chart showing the transmittance characteristics of a conventional band-pass filter.
- Now, the first embodiment according to the present invention will be described. In this embodiment of the illuminating apparatus differs from the conventional illuminating apparatus in that the
mercury lamp 1 is replaced by a new one having double-bulb structure. First, this double-bulb mercury lamp used in this embodiment will be described. - FIG. 1A shows the mercury lamp used in this embodiment. A tubular
inner bulb 11 has a spherical portion in the middle and the open ends one sealed bybases Electrodes bases inner bulb 11. Also substances necessary for emission of the mercury lamp are filled in the hollow inside theinner bulb 11. Thus, theinner bulb 11 with other necessary components functions as an ordinary ultra-high pressure mercury lamp. Further, a tubularouter bulb 19 also having a spherical portion in the middle surrounds theinner bulb 11. The doughnut-shaped openings at both ends of theouter bulb 14 are sealed bybases inner bulb 11 and theouter bulb 14. - As described before, the ultra-high pressure mercury lamp used in the projection exposure apparatus has the emission spectrum distribution shown in FIG. 13. As is clearly shown in FIG. 13, the ultra-high pressure mercury lamp has distributions in a wavelength range from 260 to 340 nm, that is, the wavelength range causing adhesion of the white powder (blurring phenomenon). In order to prevent emission of light in said wavelength range, the mercury lamp has the double-bulb structure and the gas which absorbs light having wavelength in the range from 260 to 340 nm is filled in the space S between the
inner bulb 11 and theouter bulb 14, as described above. Gases having such proper absorption characteristics include metallic vapour of rubidium, caesium, and so on. - According to a literature (R. D. Hudson and L. J. Kieffer, “Compilation of Atomic Ultraviolet Photoabsorption Cross Sections for Wavelengths Between 3000 and 10 Å”,
Atomic Data 2, pp 205-262 (1971) especially, see p. 235 and p. 253), FIG. 2 shows the absorption cross section spectrum of vaporous rubidium. According to the same literature, FIG. 3 shows the absorption cross section spectrum of vaporous caesium. As is shown in FIGS. 2 and 3, both vaporous rubidium and vaporous caesium have large absorption cross sections for wavelength of 340 nm and shorter wavelengths. Accordingly, if such metallic vapor is sealed in the space S of the double-bulb structure shown in FIGS. 1A and 1B, the light in said wavelength range causing the blurring phenomenon can be selectively removed from the light emitted from the inner bulb serving as an ultra-high pressure mercury lamp. - Gaseous ozone has absorption characteristics similar to those of the above metallic vapor. The absorption cross section spectrum of gaseous oxygen (O2) and ozone gas (O3) are shown in FIG. 4, in which
reference numeral 17 indicates the absorption cross section spectrum of gaseous oxygen andreference numeral 18 indicates that of ozone gas. As is clearly shown is FIG. 4, the absorption spectrum of ozone gas (O3) has ideal absorption characteristics for wavelength of or shorter than 340 nm. The ozone gas, however, unlike metallic vapor, dissociates to be O and O2 in photochemical reactions. Photochemical reactions of ozone and oxygen occurs as shown in the following (in the following reaction formulas M, which is called a third body any atom, molecule or ion except an oxygen atom, for example, a molecule of oxygen (O2) or nitrogen (N2)). -
- wherein n is concentration of each substance.
-
-
- is the number of photons passing per second per unit wavelength per unit area, σ(λ)[cm−2] is the photoelectric absorption cross section of a molecule, and λmax is the maximum wavelength of λ in the above reactions.
- The reaction rate of each reaction can be obtained from well-known literature. Light absorption efficiency can be promoted by increasing pressure of the gas filled in the double-bulb structure shown in FIG. 1A. But temperature rising caused by light absorption must be taken into account. That is, both the
inner bulb 11 and theouter bulb 14 have to be made of glass material having a small coefficient of thermal expansion as well as enough strength. - The gas which absorbs light having wavelength from 260 to 340 nm may be circulated through the space S between the
inner bulb 11 and theouter bulb 14, as shown in FIG. 1B. In this case, the gas is supplied through apipe 16A into the space S by a gas supplier (not shown), wherein conditions of the gas (density, pressure, flow velocity, temperature, and so on) must be well controlled. The gas is exhausted through anotherpipe 16B to an exhaust system (not shown). By circulating the gas through the double-bulb structure, high light absorption efficiency can be maintained. - When the structure shown in FIG. 1B is adapted, additional systems are required to monitor and control the pressure and the temperature of the gas circulated through the double-bulb structure. The systems for monitoring and controlling the pressure and the temperature of metallic vapor are very large. So metallic vapor is preferably filled in the double-bulb structure, as shown in FIG. 1A, when it is desirable to simplify the construction of the whole apparatus. Accordingly, in practice, ozone gas is usually circulated through the double-bulb structure shown in FIG. 1B. In this case, however, the density of ozone circulated through the double-bulb structure has to be newly calculated. If the time required to reach the equilibrium is much longer than the time during which the gas remains inside the double-bulb structure, the initial density of ozone has to be high. Otherwise, the flow velocity is changed to obtain desirable densities of ozone.
- Next, the second embodiment according to the present invention will be described with reference to FIGS. 5 and 6. This embodiment has construction similar to that shown in FIG. 12, wherein an impurity having certain absorption characteristics is doped in the bulb of the
mercury lamp 1. First, the structure of the mercury lamp used in this embodiment will be described. - FIG. 5 shows the mercury lamp of this embodiment. A
tubular bulb 19 has a spherical portion in the middle. The openings of thebulb 19 are sealed bybases Electrodes bulb 19 through thebases bulb 19 with other necessary components functions as an ordinary ultra-high pressure mercury lamp. An impurity which absorbs light having wavelength of 340 nm and shorter wavelengths is doped in quartz glass, of which thebulb 19 of thelamp 1 is made. - One of materials which are preferably doped in quartz glass is sodium Na. Sodium Na, however crystallize SiO2 at high temperatures, which blurs the
bulb 19. Accordingly, thebulb 19 has to be kept at a temperature of 1000° C. or lower. Other preferable materials to be doped in quartz glass includes iron Fe, lead Pb, aluminum Al, rubidium Rb, caesium Cs, and so on. - The
bulb 19 can be made of materials on the market. For example, ULETM titanium silicate glass (manufactured by Corning Co., Commodity No. 7971) can be used without doping an impurity. This ULETM titanium silicate glass absorbs light having a wavelength of 300 nm and shorter wavelength, so the lamp can be effectively prevented from being blurred. - Also glass material LF5W manufactured by Ohara Co. is useful. This glass material LF5W exhibits light transmittance characteristics shown in FIG. 6. The transmittance of this material having a thickness of 10 mm for the light having a
wavelength 365 nm (i line) is 0.994, from which reflection loss has already subtracted. This glass material having said characteristics can satisfy conditions required according to this embodiment. This glass material, however, causes solarization when used at low temperatures. In addition, it can not be used at 400° C. or higher temperatures. Accordingly, thebulb 19 has to be controlled in the temperature range from 100° C. to 400° C. - Now, the third embodiment of the present invention will be described with reference to FIGS. 7, 8 and9. This embodiment also has construction similar to that shown in FIG. 12, wherein the glass of the
mercury lamp 1 is coated with a multilayered film. The same members as those of the previous second embodiment are indicated by the same reference numerals and detailed description thereof is omitted. First, the structure of the mercury lamp used in this embodiment will be described. - The mercury lamp of this embodiment shown in FIG. 7 has a
bulb 22 made of ordinary glass material. Theouter surface 22 a of thebulb 22 is coated with amultilayered film 10, which reflects light having wavelengths in arange 260 to 340 nm and transmit light having wavelength of 350 nm or longer wavelength. In other words, the multilayered film selectively transmits the light used as exposure light. An example of the multilayered film having selectivity with respect to wavelengths is designed as: - wherein: H is selected from a group including ZrO2, Sc2O3, HfO2, Y2O3, and so on; L is selected from a group including SrO2, MgF2, and so on; the wavelength λ is determined to be about 300 nm; and the number of layers n is generally from 8 to 16.
- FIG. 8 shows a cross section of such a multilayered film, wherein the film is formed according to the above design (5) and the number of layers is 10. As the substrate, materials which transmit light having a wavelength of 350 nm or longer wavelengths can be used, including optical glass, quartz glass, fluorite, and so on. When the material employed as the substrate absorbs light having a
wavelength 340 nm or shorter wavelengths, such light can be prevented from being transmitted more effectively. By coating the glass of the mercury lamp with the multilayered film, blurring of the other optical members in the illuminating apparatus can be reduced. - Next, the fourth embodiment of the present invention will be described with reference to FIGS. 10 and 11. The components in FIG. 10 corresponding to those in FIG. 12 are indicated by the same reference numerals, and detailed description thereof is omitted. In this embodiment, an optical filter which absorbs light having wavelengths from 260 to 340 nm is provided in the optical path of the illuminating optical system.
- FIG. 10 schematically shows the construction of this embodiment. As shown in FIG. 10, a
box member 20 is arranged between theellipsoidal mirror 2 and themirror 3. The box member has two flat glass surfaces parallel to each other. FIG. 11 shows a broken-out section of the box member. Thebox member 20 has ahollow space 21, which is arranged to coincide with the optical path. A gaseous substance which absorbs light having wavelengths from 260 to 340 nm (cf. description of the first embodiment) is filled in thehollow space 21. The box member is arranged preferably in the vicinity of themercury lamp 1, as shown FIG. 10. Thebox member 20 reduces adhesion of the white powder on the optical members arranged downstream in the optical path from thebox member 20. - The glass material of the
box member 20 may be the glass material used in the second embodiment, that is, the glass material which absorbs certain undesirable light. Or thebox member 20 may be replaced by a plane parallel glass which has absorption characteristics similar to those of the glass materials used in the second embodiment. In addition to the glass materials used in the second embodiment, the plane parallel glass provided in the illuminating optical system may be also made of a crystalline material (for example, fluorite CaF2, magnesium fluoride, and so on) to which the above-mentioned metal (such as Na, Fe, and so on) is doped. - This fourth embodiment is useful in case, for example, the double-bulb structure employed in the first embodiment is difficult to manufacture.
- The illuminating apparatus according to the present invention can be applied not only to the projection exposure apparatus as described but also to a proximity-type exposure apparatus and a contact-type exposure apparatus, and further any type of optical apparatus using ultraviolet rays.
- As described before, ammonium sulfate is formed from trace sulfur dioxide (SO2) and ammonia (NH3) existing in the ambient atmosphere in which the illuminating apparatus is used. Accordingly, if the illuminating apparatus is installed in a clean room, sulfur dioxide (SO2) and/or ammonia (NH3) may be removed from the air circulated in the clean room by attaching a filtering system for removing sulfur dioxide (SO2) and/or ammonia (NH3) to the air conditioning system. Thus, formation of ammonium sulfate can be reduced.
- The devices of the first to fourth embodiment can be used separately. But if used in combination, these devices can more effectively prevent adhesion of the white powder. Note that the present invention is not limited to the above-mentioned embodiment. The present invention includes any construction which concerns the fundamental principles of the present invention.
Claims (13)
1. An illuminating apparatus comprising:
a light source;
an optical system disposed in an optical path of a light emitted from said light source to condense the light emitted from the light source and illuminate an object with the condensed light; and
an optical member disposed in said optical path, and exhibiting an absorbing property for light having wavelength from 260 to 340 nm among the light emitted from the light source, to suppress formation of ammonium sulfate that would otherwise form in the absence of said optical member,
wherein said optical member is made of glass or crystalline material doped with an impurity that has said absorbing property.
2. An apparatus according to claim 1 , wherein said impurity comprises at least one of Na, Fe, Pb, Al, Rb and Cs.
3. An illuminating apparatus according to claim 1 , wherein said object is a mask on which a pattern is formed, and the illuminating apparatus is provided in an apparatus for transferring the pattern on the mask onto a photosensitive substrate.
4. An illuminating apparatus comprising:
a light source;
an optical system for condensing light emitted from the light source and illuminating an object with condensed light; and
an optical member in which fluid absorbing light having wavelength from 260 to 340 nm among the light emitted from the light source is filled.
5. An illuminating apparatus according to claim 4 , wherein said fluid is one of gaseous rubidium, gaseous caesium and ozone gas.
6. An illuminating apparatus according to claim 4 , wherein said object is a mask on which a pattern is formed, and the illuminating apparatus is provided in an apparatus for transferring the pattern on the mask onto a photosensitive substrate.
7. An apparatus according to claim 1 , wherein said optical member is made of crystalline material doped as aforesaid, and said crystalline material is one of fluorite (CaF2) and magnesium fluoride (MgF2).
8. An apparatus according to claim 1 , wherein said light source comprises a discharge lamp and a light reflecting-condensing member to reflect and condense the light from the discharge lamp so as to direct the light to said object.
9. An apparatus according to claim 8 , wherein said optical system includes a wavelength selecting element which selects a light of a predetermined wavelength band among the light emitted from said light source, and wherein said optical member is disposed between said reflecting-condensing member and said wavelength selecting element.
10. An exposure apparatus for transferring a pattern formed on a mask onto a substrate with a light emitted from a light source, comprising:
an illumination optical system disposed between said light source and said mask, and which illuminates said mask with the light emitted from the light source; and
an optical member disposed in said optical path, and exhibiting an absorbing property for light having wavelength from 260 to 340 nm among the light emitted from the light source, to suppress formation of ammonium sulfate that would otherwise form in the absence of said optical member,
wherein said optical member is made of glass or crystalline material doped with an impurity that has said absorbing property.
11. An apparatus according to claim 10 , wherein said light source comprises a discharge lamp and a light reflecting-condensing member to reflect and condense the light from the discharge lamp.
12. An apparatus according to claim 11 , wherein said illumination optical system includes a wavelength selecting element which selects a light of predetermined wavelength band among the light emitted from said light source, and wherein said optical member is disposed between said reflecting-condensing member and said wavelength selecting element.
13. An apparatus according to claim 12 , wherein said impurity is at least one of Na, Fe, Pb, Al, Rb and Cs.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/139,362 US20020159142A1 (en) | 1993-10-26 | 2002-05-07 | Illuminating apparatus |
Applications Claiming Priority (7)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP26720893A JP3367167B2 (en) | 1993-10-26 | 1993-10-26 | Illumination optical device, discharge lamp used in the device, and exposure device |
JP5-267208 | 1993-10-26 | ||
US32881694A | 1994-10-25 | 1994-10-25 | |
US84251497A | 1997-04-24 | 1997-04-24 | |
US09/131,320 US6108126A (en) | 1993-10-26 | 1998-08-07 | Illuminating apparatus |
US58426600A | 2000-06-01 | 2000-06-01 | |
US10/139,362 US20020159142A1 (en) | 1993-10-26 | 2002-05-07 | Illuminating apparatus |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US58426600A Continuation | 1993-10-26 | 2000-06-01 |
Publications (1)
Publication Number | Publication Date |
---|---|
US20020159142A1 true US20020159142A1 (en) | 2002-10-31 |
Family
ID=17441638
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/131,320 Expired - Fee Related US6108126A (en) | 1993-10-26 | 1998-08-07 | Illuminating apparatus |
US10/139,362 Abandoned US20020159142A1 (en) | 1993-10-26 | 2002-05-07 | Illuminating apparatus |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/131,320 Expired - Fee Related US6108126A (en) | 1993-10-26 | 1998-08-07 | Illuminating apparatus |
Country Status (2)
Country | Link |
---|---|
US (2) | US6108126A (en) |
JP (1) | JP3367167B2 (en) |
Families Citing this family (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6590219B1 (en) * | 2000-06-28 | 2003-07-08 | Koninklijke Philips Electronics N.V. | Apparatus and method for forming photoresist pattern with target critical dimension |
WO2002025710A1 (en) * | 2000-09-19 | 2002-03-28 | Nikon Corporation | Exposure system, exposure method, and production method for device |
DE10063376A1 (en) * | 2000-12-19 | 2002-06-20 | Philips Corp Intellectual Pty | High pressure discharge lamp used as a light source in digital projection systems comprises a longitudinally extended bulb having two throat regions and a vacuum-tight discharge chamber |
KR100464709B1 (en) * | 2001-03-12 | 2005-01-06 | 가부시키가이샤 고이토 세이사꾸쇼 | Discharge lamp device |
EP1384245A4 (en) * | 2001-03-30 | 2005-03-16 | Advanced Lighting Tech Inc | An improved plasma lamp and method |
US6859309B2 (en) * | 2001-12-19 | 2005-02-22 | 3M Innovative Properties Company | Optical filters for manipulating spectral power distribution in accelerated weathering devices |
US20040233520A1 (en) * | 2001-12-19 | 2004-11-25 | 3M Innovative Properties Company | Optical filters for manipulating spectral power distribution in accelerated weathering devices |
US6984058B2 (en) | 2003-06-04 | 2006-01-10 | 3M Innovative Properties Company | Optical filters comprising opacified portion |
JP2005197191A (en) * | 2004-01-09 | 2005-07-21 | Ushio Inc | Ultrahigh pressure mercury lamp and light irradiation device using the ultrahigh pressure mercury lamp |
US8094288B2 (en) * | 2004-05-11 | 2012-01-10 | Asml Netherlands B.V. | Lithographic apparatus and device manufacturing method |
US20070262695A1 (en) * | 2006-05-11 | 2007-11-15 | Reisman Juliana P | UV and near visible lamp filter |
EP2287644B1 (en) * | 2009-08-18 | 2014-04-09 | Mitsubishi Electric Corporation | Light source device and method of producing the same |
US8603292B2 (en) * | 2009-10-28 | 2013-12-10 | Lam Research Corporation | Quartz window for a degas chamber |
US8584612B2 (en) * | 2009-12-17 | 2013-11-19 | Lam Research Corporation | UV lamp assembly of degas chamber having rotary shutters |
US8492736B2 (en) | 2010-06-09 | 2013-07-23 | Lam Research Corporation | Ozone plenum as UV shutter or tunable UV filter for cleaning semiconductor substrates |
KR101295700B1 (en) * | 2011-08-08 | 2013-08-14 | 김우섭 | Lamp of Exposure Apparatus in Photo Lithography System or LCD Hardening System |
NL2013513A (en) * | 2013-10-17 | 2015-04-20 | Asml Netherlands Bv | Photon source, metrology apparatus, lithographic system and device manufacturing method. |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3813421A1 (en) * | 1988-04-21 | 1989-11-02 | Philips Patentverwaltung | HIGH PRESSURE MERCURY VAPOR DISCHARGE LAMP |
US4907029A (en) * | 1988-08-11 | 1990-03-06 | Actinic Systems, Inc. | Uniform deep ultraviolet radiant source for sub micron resolution systems |
US5214345A (en) * | 1989-03-28 | 1993-05-25 | Sumitomo Cement Company, Ltd. | Ultraviolet ray-shielding agent and tube |
JP3266156B2 (en) * | 1990-09-19 | 2002-03-18 | 株式会社ニコン | Illumination light source device and exposure device |
US5196759B1 (en) * | 1992-02-28 | 1996-09-24 | Gen Electric | High temperature lamps having UV absorbing quartz envelope |
-
1993
- 1993-10-26 JP JP26720893A patent/JP3367167B2/en not_active Expired - Fee Related
-
1998
- 1998-08-07 US US09/131,320 patent/US6108126A/en not_active Expired - Fee Related
-
2002
- 2002-05-07 US US10/139,362 patent/US20020159142A1/en not_active Abandoned
Also Published As
Publication number | Publication date |
---|---|
JPH07122477A (en) | 1995-05-12 |
JP3367167B2 (en) | 2003-01-14 |
US6108126A (en) | 2000-08-22 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US20020159142A1 (en) | Illuminating apparatus | |
JP3448670B2 (en) | Exposure apparatus and element manufacturing method | |
US7061573B2 (en) | Contamination prevention in optical system | |
US7116397B2 (en) | Exposure apparatus and device manufacturing method | |
JP2670020B2 (en) | Lighting unit | |
WO2001023933A1 (en) | Projection optical system | |
US7455880B2 (en) | Optical element fabrication method, optical element, exposure apparatus, device fabrication method | |
KR20130135115A (en) | Unit-magnification large-format catadioptric lens for microlithography | |
KR20010112265A (en) | Exposure method and apparatus | |
TW201544844A (en) | Wynne-Dyson projection lens with reduced susceptibility to UV damage | |
US6587181B2 (en) | Optical system with improved durability for projection exposure apparatus and method for manufacturing optical system for projection exposure apparatus | |
JP3309867B2 (en) | Exposure device and illumination optical device | |
US6552846B1 (en) | Catoptric optical element, illumination optical system equipped therewith, projection exposure apparatus and method for manufacturing semiconductor device | |
WO2003050857A1 (en) | Reflective illuminating optical element, reflective illuminating optical system, and duv to euv exposure device | |
JP4618552B2 (en) | Ultraviolet optical device and light source device | |
JPH0825773B2 (en) | Manufacturing body of laser optical system | |
Ikuta et al. | New silica glass (AQF) for 157-nm lithography | |
JPH03284827A (en) | Exposure light source of exposure device for manufacturing semiconductor | |
JPH11109101A (en) | Optical member for laser beam | |
JPH10218636A (en) | Optical quartz glass member | |
JPH04204904A (en) | Device and method for production of semiconductor | |
JP2003234263A (en) | Method for controlling deterioration of optical element and optical device using the same | |
JP2005031483A (en) | Original plate for exposure and inspection method and exposure method for original plate for exposure |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO PAY ISSUE FEE |