CN1704180A - Optical performance restoring equipment, restoring method and optical system used for the equipment - Google Patents

Abstract

The invention relates to an optical device which can prevent or depress the wane of optical system which designed the life of optical device. It can achieve the effect such as optical transmission, optical diffraction, optical reflection, spectrum generation, optical impulsion and its combination. It has the following steps: generating near-empty space with active energy to excite the oxidizing reaction of carbon, wherein the said near-empty space is opposed faced to the surface of optical system; the said near-empty space generates negative ion or group such as unstable group with oxygen atom like OH group, OH.-. ion, ozone, O.2..-. ion and O.-. group.

Description

Optical property restorer, restoration methods and the optical system that is used for this equipment

Technical field

The present invention relates to a kind of being used for by preventing, suppress or improve to be present in output light or along the decay of the optical property of the optical system of the opticpath of described output light, improve reliability and the equipment in life-span and the method for the optical property of optical system, wherein said optical system is arranged on the nearly vacuum zone that organic composition can decompose, described decay produces by deposition or the carbon that accumulates on the irradiate light surface, light reflecting surface, light emission surface (being called " light surface " jointly) of described optical system, and described surface is in the face of described vacuum zone.More particularly, the method that it relates to a kind of optical property restorer and uses it, this optical property restorer is by utilizing the ultraviolet ray or the vacuum ultraviolet ray of high photon energy light such as routine, be used to improve be arranged on produce light transmission, refraction, reflection, spectrum produces and the optical property of the various optical systems of the light transmission window outside of the various optical devices of net effects such as interference.

In addition, the present invention relates to various optical devices and use optical system in its method.Optical system is improved the interior optical property of light transmission window of the various optical devices of net effects such as the transmission of various generation light, refraction, reflection, spectrum generation and interference, and optical system is arranged in the ultraviolet ray or vacuum ultraviolet opticpath of high photon energy light such as routine.More particularly, the present invention can be applied to the optical system that disposes lens, window, etalon, prism, wire cross and speculum etc., and the high photon energy lamp that disposes this optical system.In addition, the present invention not only can be applied to optical measuring apparatus, as spectrometer, photofluorometer, interferometer, diffractometer, and can be applied to the combination be used for vacuum ultraviolet standard light source, be used to the various optical devices that excite the light source of chemical reaction, printing plate and photograph occasion and be used for the various light sources of experimental occasions.

Background technology

Figure 14 is used to illustrate assembly and the operation as the microwave-excitation hydrogen UV-lamp of the operable traditional optical output equipment of the present invention embodiment.This equipment is at the JamerA of non-patent literature 1, R.Samson writes, 1967 in Licon, " the vacuum ultraviolet ray spectroscopy techniques " that Nebraska is published by Pied, Fig. 5 .56 in the P159 page or leaf is illustrated.Microwave oscillator 4 has the sealing cast parts that are provided with the two ends that made by same conducting material.The internal diameter of pipe and length distribute according to ELECTROMAGNETIC FIELD in the frequency of using microwave and the microwave oscillator and determine.

Microwave oscillator tuner 18 is the cast spare of the necessary parts of the microwave oscillator of the microwave electromagnetic field profile adjustment of permission microwave oscillator, and its internal diameter is so that it can hide discharge tube 1.In addition, it inserts with the end surfaces of microwave oscillator 4 is concentric along its axially bored line, and its structure is can endwisely slip when it keeps it to play microwave oscillator 4 electric guide effects with box lunch.The same with microwave oscillator 4, the material that is used to form tuner 18 is copper or brass.Undertaken by regulating its depth of penetration by the function that described tuner 18 is regulated the microwave electromagnetic field distribution, produce plasma body 7 simultaneously, thereby make microwave concentration 6 enter required occurrence positions.

In addition, discharge tube 1 is settled in this way so that its two end surfaces by microwave oscillator 4.Though its maximum electric field produces along the axially bored line of the discharge tube 1 of the axially bored line placement of microwave oscillator 4 usually, neither be always like this.The cross-sectional shape of discharge tube 1 is circular, but it too can be for square etc.

Discharge tube 1 as vacuum boundary, be used for flow passage and isoionic generation space as discharge gas.In the embodiment shown in fig. 14, in order to limit the space that plasma discharging produces, 4 end surfaces extends in microwave oscillator the interior pipe of conductor always along discharge tube 1 from microwave oscillator.Therefore, the space of plasma discharging 7 between the end of microwave oscillator tuner 18 and above-mentioned inner tube portion produces.

Microwave oscillator 4 is connected with the microwave of carrying microwave and supplies with junctor 5.At this, being shaped as of junctor is co-axial, but it also can be waveguide type, no matter is that concentric cable or coaxial valve can be as the transmission feeding paths that is connected to coaxial connector.

Flange 17 connects to keep the original position of lamp on microwave oscillator tuner 18 lateral discharge tube 1 ends by O type circle 13.There is opening center at above-mentioned flange 17, and it has and discharge tube 1 corresponding internal diameter, so it allows from the axial discharge at discharge tube 1 of the light of plasma discharging 7 emissions.

The light transmission window 8 that is fixed in above-mentioned flange 17 openings has two effects.One arrives atmospheric vacuum boundary as the inside of discharge tube 1.It two is discharged to the vacuum outside for making from the light of plasma discharging 7 emission.Above-mentioned microwave oscillator the E.L.Ginzton in non-patent literature 2 write, nineteen fifty-seven McG-Hill, being illustrated of " microwave measurement " that New York publishes.

Discharge lamp with said structure has following problems, but before it is described, the definition of its term will be described at first.

Vacuum ultraviolet wavelength region is 0.2 to 200nm.Light in this scope is called ultraviolet or vacuum ultraviolet (VUV) linear light.The conventional wavelength of ultraviolet is 200 to 380nm (referring to the physics dictionary, Baifukan publishes, and the Rika Nenpyo of Japanese national observatory (National Observatory ofJapan) publication).

In Figure 14, in order to distinguish light transmission window surface, the surface of facing plasma discharging 7 is called internal surface 10, and the surface of opposite side is called exterior outside surface 11.

The problem of light transmission window external optical performance degradation

In Figure 14, when 7 generation light, particularly ultraviolet or the vacuum ultraviolet ray light time of plasma discharging, its internal surface 10 by transmission window 8 passes transmission window 8 irradiations, and passes from the exterior outside surface 11 of light transmission window 8.

At this, when ultraviolet ray or vacuum ultraviolet (VUV) linear light were launched in atmosphere, this light produced oxygen, the remarkable absorption of carbonic acid gas, water vapor etc., so as shown in figure 14, usually has the mechanism that helps to keep vacuum in the left side (that is the outside of light transmission window 8) of flange 17.The zone that keeps this vacuum is hereinafter referred to as " vacuum zone ".

That is, can use any of various vacuum pumps as the mechanism that keeps vacuum.Though the various no oily dried pumps of fit for service (it produces organic gas hardly) are also arranged, the most frequently used still rotary-type pump.Therefore, vacuum zone 14 comprises to come the organic gas that uses the vapour pressure of oil in the self-pumping.

In addition, stainless steel or metal aluminum component or rubber seal such as O type circle are also included within the vacuum zone 14, and according to the application scenario, vacuum zone 14 also can comprise as exemplar, lens, diffraction spare, speculum, spectral filter, transmission window, dressing table or other positioning element etc.In theory, the all material that contacts with above-mentioned vacuum zone 14, that is, stainless steel vessel, aluminum container, O type circle and other sealing material, optical element, work exemplar, position adjusting mechanism etc. all should be for there not being oil (its meaning does not discharge for organic gas should not be arranged itself).

Specifically, in semi-conductor industry, finish size (width of circuit lead) becomes more and more thinner, and the wavelength of light that is used for the exposure figure of circuit has reached vacuum ultraviolet scope.For example, the wavelength that is used for the argon fluoride excite state atom laser of this application scenario light source is 193nm (being 6.4eV when it is converted into energy), but in recent years, developmental research goes out to produce the laser stepper devices of 157nm wavelength.

Yet, in actually operating, be difficult to avoid by various factors as the lubricating oil that is used for mechanical driving structure, the pollution of working prototype, venting, the venting of plastic component, the inadequate degreasing of part or cleaning or because the radiation of organic gas in the vacuum zone 14 that the various factorss such as pollution that mistake produces cause of O RunddichtringO.Therefore, in actual applications, must consider the appearance of organic gas in above-mentioned vacuum zone.

Organic gass in the vacuum zone 14 have the possibility of certain absorption on the exterior outside surface 11 of light transmission window 8.This absorbs possibility according to the changes in material that comprises light transmission window 8 and organic gas type, but the appearance of absorbing phenomenon itself is inevitable.

When organic gas was absorbed on the exterior outside surface 11, the ultraviolet, particularly vacuum ultraviolet ray that produce by the plasma that shines these organic gass can make the organic gas molecule directly excite to be active condition.This just produces the reaction that attracts hydrogen, i.e. the dehydrogenation reaction of organic gas component, and last, the organic gas of absorption is converted into carbon (graphite).When reaching this state, it is a gas no longer just, but solid, it adheres to itself or accumulates on the outside surface 11 of light transmission window 8.Then, the carbon that gathers absorbs new organic gas, and they also are translated into carbon equally by ultraviolet, particularly vacuum ultraviolet ray rayed, and further piles up.Along with the continuation of this process, the outside surface 11 of light transmission window 8 becomes and is covered by carbon film.Because carbon is black, therefore absorb the light of various wavelength, and along with the poly-continuation of carbon deposit on the outside surface 11, the transmissivity by light transmission window 8 descends gradually.

At this, simplify for making explanation, suppose that organic gas is a hydrocarbon gas, and dehydrogenation reaction causes it to be converted into graphite, but in actually operating, organic gas may comprise the not only element as oxygen, nitrogen, iodine, fluorine, chlorine etc. of hydrocarbon element, this organic gas also can absorb on the outside surface 11 of light transmission window 8 as hydrocarbon gas, then, passes through ultraviolet, particularly vacuum ultraviolet effect transforms, and the on-gaseous composition carries over as residue.Therefore, say on the stricti jurise, formation be not graphite, but be a kind of amorphous solid of main component with carbon.For the present invention is described, this solid that mainly comprises carbon is called " carbon ".

The phenomenon of coke build-up needs the absorption of organic gas and passes through ultraviolet, the particularly irradiation of vacuum ultraviolet (VUV) linear light.Along with poly-the carrying out of carbon deposit, from the ultraviolet of poly-outside surface 11 emissions of carbon deposit, particularly vacuum ultraviolet intensity obviously reduces.Coke build-up will continue till all light intensities are weak gradually.Simultaneously, because new dehydrogenation reaction can not take place, so gathering of carbon film stops.Therefore in a single day, this process is not the process that carbon film can increase without limitation, and just stops but reaching limited this phenomenon of film thickness.

Generally, the phenomenon that forms on the outside surface 11 of above-mentioned light transmission window 8 of carbon can not carried out very soon.But one of problem be by light transmission window 8 transmission to reduce be secular.In spectrum of use, when the light amount of sending from light source reduces, the drift of its measuring accuracy that exerts an influence, and in carry out the surface-treated application by uviolizing, because the minimizing of exposure intensity will cause the not enough problem of handling.

A kind of method that solves this coke build-up phenomenon problem is to be used for oil-free vacuum district 14 as far as possible, yet in case organic substance has polluted vacuum zone 14, clean is just very difficult.Therefore, for the minimizing that causes transmissivity on the outside surface 11 that accumulates in light transmission window 8 owing to carbon, traditional counte-rplan are exactly with sanitising agent or polish to remove carbon, recover light transmission window 8 to its initial conditions, or integral replacing light transmission window 8.

In the prior art, the decline of the optical transmittance of light transmission window 8 is that its decay is the determinative in lamp life-span.The lamp that has reached its life-span need clean or change its light transmission window 8, and this will destroy the vacuum in vacuum zone 14 or the lamp.This out of use time of manipulation require several hrs lamp.

Then, explanation is corresponding because the poly-traditional scheme that causes the decay of transmission window transmissivity of carbon pile.

Disclosed technology among the Japanese Unexamined Patent Publication No No:2001-319618 (patent documentation 1) will be described below.

In this example, the light source of discussion is a hydrogen lamp.When hydrogen entered into discharge tube, as the means that increase the lamp life-span, halogen was sealed in wherein.The halogen that is sealed in wherein is the form of organohalogen compound.This just means that the organic halogen material has entered region of discharge.Then, when lamp in when work, organic substance decomposes and produces the organism plasma membrane that is mainly carbon and adheres on the inwall of discharge tube.This inwall is as the light transmission window, and sticks to the decline that material on its wall causes the light amount.As a kind of scheme, patent publication us 1 cited above has proposed the method for dosing processing in advance of lamp, and it can force and make carbon film adhere to the zone as light transmission window of illusion at lamp on period coke build-up, then, when the lamp works better, other coke build-up just can not appear again.Can think that this technology has limited the generation of organic materials limitedly, and its counte-rplan can produce the environment that the lamp on period does not form new carbon effectively.

Yet, in the above-mentioned explanation that is used for vacuum zone 14, if the equipment of vacuum is opened or removed to the equipment that uses frequently (as changing in the spectrum of use of sample to atmosphere as needs, must regulate in the application of optical element, or during surface treatment, need situation about changing by workpiece etc.), there is not organic contamination to enter even in assembling and regulate process, require in the specification sheets at all, but not producing this pollution in actually operating also is difficult to, therefore, will unavoidably make 8 decay of light transmission window.

Other Japanese Unexamined Patent Publication No No:2001-293442 (patent documentation 2) relates to a kind of purging method that is adsorbed on the optical element surface organic substance of removing by the following method, the minimum step that comprises of its method: (1) cleans the process of optical element with organic solvent, (2) process of usefulness uviolizing optical element under the condition that oxygen exists, and the process of described optical element is heated and cleaned in (3).This publication not only has the purpose that is different from the carbon film that gathers from surface removal really, but it does not still have to solve the problem that cleans optical element such as light transmission window when needing to destroy vacuum.

In addition, Japanese Unexamined Patent Publication No No:2002-219429 (patent documentation 3) discloses the technology of the present invention that is similar to.Its purpose is to improve the processing accuracy and the processing efficiency of cleaning etc., and it is characterized in that comprising substrate of glass, synthetic resin substrate, ceramic bases, metal base and comprise that the combined substrate of the one or more substrates of above-mentioned substrate bedews on the atmospheric internal surface of the heating that contains water vapor, then, substrate is used uviolizing in the mixed gas of rare gas element that heats and water vapor, it is for lower than the concentration that exists in the wet air, thereby be used to dissolve the organic substance that adheres to described substrate surface, in addition, produce reducing activity base (seeds) [H-] and oxidation activity base [OH], these active groups [H-] and active group [OH] react with the degradation production of organic substance.

The purpose of described prior art is not to eliminate carbon film from the surface, its objective is by it being reduced to littler molecule and adhere to organic bur of substrate surface with dissolving, particularly use the uviolizing substrate surface, and utilize the means that ultraviolet light shines as base treatment to clean and etch processes.Not only its purpose is different from the present invention, and because substrate surface must be in saturation conditions, so its prerequisite is to be liquid water under reaction conditions.As a result, environment-its optical element that can not carry out the light transmission window that present method only can be used in nearly normal atmospheric pressure cleans, and under vacuum condition, it can only solve the problem of studying when needing to destroy vacuum equally.

Though reach the phenomenon that the explanation of this point is confined to generation on the outside surface 11 of light transmission window 8, the phenomenon of this coke build-up form is not only limited to the outside surface 11 of light transmission window 8 always.Generally, the phenomenon of coke build-up occurs in and is arranged in vacuum zone 14 by from the ultraviolet ray of the light transmission window 8 emissions ultraviolet object surfaces of vacuum ultraviolet ray irradiation particularly.As long as the common condition that exists of organic gas and ultraviolet ray, particularly vacuum ultraviolet ray exists, this phenomenon is just inevitable." object " mentioned in the above description be included in the spectrum of use conversion opticpath speculum, spectral filter, be used for the lens of focused ray and be used in the diffraction element of spectrum of use, the various spectral filters that are used for the lens of focused ray and are used for surface-treatment applications, in other words, be any one of various optical elements.Hereinafter, any this object all is called " optical element " on the whole.When carbon accumulated on these optical elements, it was owing to reduced its light transmission and the serious problem of light reflection generation.In actually operating, its reduction or make in the vacuum zone 14 the whole forfeiture of effect of the equipment of use.

In the past, in order to solve weakening of this light transmission and reflection, this must must change with new optical element by optical element, but this method causes high maintenance cost, and the equipment that is in the period of needing repairing can not be worked.

Because also being present in as those, the microwave-excitation hydrogen UV-lamp that the decay of light transmission window 8 causes the problem in lamp life-span to be not limited to be illustrated in the above-mentioned example, same problem use He, Ne, Ar, Kr, Xe, O ₂, N ₂, D ₂In the various lamps such as (deuterium molecule), Hg; Use in the lamp of high frequency discharge, arc-over, glow discharge, the discharge of induction grid or the flash discharge in its discharge mode; Or at halogen lamp or in the lamp of electric current as the carbon lamp of the heat filament of light generation means.

Optical property attenuation problem in optical system

Reduction is not limited to the outer optical property decay of light transmission window from the problem of short wavelength ultraviolet light transmission performance, and is the optical property decay in the light transmission window.

Recent years,, study SiO in order to obtain better light transmission property from short wavelength ultraviolet light ₂Be used for above-mentioned light transmission window.

In addition, the problem of mercury vapor lamp is to compare with the situation of previous usefulness even more serious, and silica glass therein loses that it is transparent.To outside vacuum boundary, it also is used to transmit the ultraviolet ray by the luminous generation of mercury to silica glass, but loses the performance that transparent phenomenon has reduced its light transmission as lamp inside in the mercury vapor lamp, and for determining the determinative in lamp life-span.

For example, at Japanese Unexamined Patent Publication No No: among the flat 5-325893 (patent documentation 4), for having proposed use light emission pipe as the evaporation of metal electric arc tube, it adopts the rough inner-surface with glass bulb of surperficial grain-size below 1 micron for the transparent scheme of taking of forfeiture.The practice will stop the crystallization (losing transparent) of electric arc tube like this, even it is also like this under the prolonged operation situation, thereby stop the decline of optical throughput (speed is kept in illumination), so that keep secular bright picture of porjection type indicating meter and high-quality display quality as far as possible.

The high-silicate glass that this technology is administered to silica glass or uses in electric arc tube, though it may be administered in the UV application of conventional 250-360nm wavelength region, will reduce the transmissivity of the vacuum ultraviolet silica glass that is used for wavelength 190nm fully.

In addition, at Japanese Unexamined Patent Publication No No: among the flat 3-77258 (patent documentation 6), the ultraviolet technology of the 254nm that is used for the constant voltage mercury vapor lamp is disclosed, wherein artificial quartz glass's internal surface is coated with 1 to 3% and has the metal oxide solution of average particle diameter below 100 μ m, is that the metal oxide of 20 μ m is formed by having average particle diameter in an embodiment.

In addition, at Japanese Unexamined Patent Publication No No: among the flat 8-212976 (patent documentation 7), disclose the technology of using by the discharge lamp of the electric arc tube that is sealed the quartz glass tube in it by mercury and form in every end sealed electrode, it uses Al ₂O ₃Cover Deng film on the internal surface of pipe, wherein the thickness at above-mentioned electric arc tube internal surface upper film near tube hub is thicker than the thickness of other regional film; Specifically, in above-mentioned electric arc tube internal surface thick film zone is 1/3 to 1/2 length of effective sunlight transmission length, it is the distance between the arbitrary tip electrodes of electric arc tube, so that in the film thickness scope in above-mentioned thick film zone from 0.2 μ m to 0.3 μ m, and in the film thickness scope of other regional extent from 0.1 μ m to 0.15 μ m.

Yet; this prior art relates to the silica glass technology; the technology of in the low-pressure mercury discharge tube, using particularly; it regulates the thickness of the protective membrane that exists as the mercury atom that solves mercury deposition problem means on the electric arc tube inwall; thereby reduce light by silica glass transmissivity and make the discharge tube blackening, further reduce its illumination efficiency.

In addition, SiO ₂The lower limit that transmits good light transmittance is approximately the 200nm level; The light transmission sharply descends with having the shortwave vacuum ultraviolet ray that is lower than the 200nm wavelength.In addition, as being used as high-octane fluorine laser with near the very short vacuum ultraviolet ray wavelength the 150nm, not only above-mentioned optical transmittance descends, and material can not stand to use and lose transparent.

In addition, consider the situation that adopts artificial silex glass, the transmissivity of passing the window material of irradiation light light transmission in ultraviolet ray range will significantly descend, at Japanese Unexamined Patent Publication No No: among the flat 8-315771 (patent documentation 5), disclose and be used for the artificial silex glass fluorine doping techniques that purpose is to improve operation lifetime.

Yet, use fluorine cpd doped silicon glass base stock only to allow about 50% transmission range of 160-190nm wavelength region, and it can not be used for lower vacuum ultraviolet ray wavelength.

Therefore, as CaF ₂, LiF, MgF ₂Usually be used for light transmission window component when the ultraviolet ray of vacuum ultraviolet ray range must be transmitted Deng the alkali halide material always.

The suitable embodiment of prior art is above-mentioned microwave-excitation hydrogen UV-lamp, and it produces the vacuum ultraviolet ray of 122nm wavelength.Unique known materials that can be used for the light transmission window is CaF ₂, LiF and MgF ₂, because LiF and MgF ₂Has the light transmission that sharply reduces from its color center, so MgF ₂The most frequent use.Yet, any relating to being used for MgF, do not disclosed ₂Lose the report of counte-rplan clearly.

That is, when using magnesium fluoride as the material of light transmission window, this window has the life-span lower than other window material, compares with the lamp that uses other material, and the life-span of lamp itself only is only about half of or still less.

When using than light in the higher photon energy of absorbing wavelength of light transmission window 8 materials useds, particularly during the light of vacuum ultraviolet (VUV) scope, when the irradiate light from plasma discharging arrives light transmission window 8, described window 8 shows defective, so-called color center produces, thereby reduces its light transmittance.This phenomenon is for CaF ₂, LiF and MgF ₂With other alkali halide material be common, and because the fluorine atom generation of slightly drifting about from its intracell tram.

In addition, above-mentioned all conventional arts that go wrong are all relevant with synthetic quartz, and are particularly relevant as the synthetic quartz optical system of light source with the ultraviolet ray with conventional wavelength.Never propose to prevent by for being used in the MgF of the vacuum ultraviolet light transmission window of 122nm wavelength that produces by microwave-excitation hydrogen UV-lamp ₂Effective practical technique of descending of light transmittance.

Given this situation, when transmissivity descended, the unique method of solution was to change the light transmission window.In this prior art, the decay of above-mentioned light transmission window 8 is the determinatives in lamp life-span.In the prior art, in case reach the life span of lamp wiring transmission window, just must change to recover the light emission intensity of lamp with new light transmission window.The replacing of light transmission window 8 need destroy the vacuum of lamp and need several hours man-hour, during this period, can not use lamp.In addition, during the replacement cycle, constant from the output intensity maintenance of light source.When changing transmission window, need carry out the operation of alignment light line strength at every turn.Therefore, be difficult to need to be used to long term monitoring as using occasion on this lamp at environment measurement.

Summary of the invention

After recognizing the problem relevant with prior art, the present invention studies, it relates to a kind of equipment and method that is used for the optical property of restorer, described equipment uses optical system realizing as effects such as light transmission, diffraction, reflection, spectrum generation and interference, and uses for example conventional ultraviolet ray of high photon energy light or vacuum ultraviolet ray.Specifically, the objective of the invention is to prevent or suppress to determine the decay of the optical system in said apparatus life-span,, reduce the frequency that maintenance operation such as window are changed, and reduce the cost of this operation by adopting such scheme.

More particularly, according to the first preferred embodiment of the present invention, the object of the present invention is to provide a kind of equipment and method that is used for its use, it is by preventing or in optical system as the surface aggregation of the optical system that is arranged on light transmission window 8 outsides (for example suppressing carbon, on the outside surface 11 of light transmission window 8 shown in Figure 14), prevent or suppress the decay of described optical system, thereby reduce the frequency of maintenance operation such as optical system replacing, also reduce the cost of this operation.

Another object of the present invention is to prolong the life-span of optical device as far as possible, and improve the reliability of these equipment by preventing or suppressing gathering on the irradiating surface of carbon optical element on the opticpath in the vacuum zone and the emitting surface.

In addition, according to second preferred implementation of the present invention, after the problems referred to above in the understanding prior art, the object of the present invention is to provide a kind of equipment and method that is used for its use, in the various device of the comprehensive action that utilizes light transmission, diffraction, reflection, spectrum and interference, it is arranged in high photon energy light source such as plasma light and the vacuum ultraviolet opticpath.Optical system will suppress as above-mentioned lens, window, etalon, prism, wire cross and speculum etc. all (for example be arranged in the optical delivery window 8, on the internal surface 10 of light transmission window 8 shown in Figure 14) the decay of optical device, thereby keep the stable and high strength of light output in whole period, to prolong the life-span of using various forms optical system equipment.

First preferred implementation

In order to address the above problem, the present invention continues research along following thinking.

At first, in first preferred implementation, make a concrete analysis of occurring in the face of the decay of light transmission window 8 outsides (as outside surface 11) of vacuum zone 14.The equipment that in experiment, uses as shown in figure 14, wherein light transmission window 8 exposes side by the plasma that O type circle is connected to flange 17.Analyze at the outside surface 11 of light transmission window 8 promptly in the face of surface for the vacuum zone 14 on the ultraviolet surface of emission.Owing on the internal surface 10 of opposite sides, do not find deposition, therefore, do not make a concrete analysis of on this surface.

Magnesium fluoride (MgF ₂) single crystal uses as the material that is used for light transmission window 8, and crystal axis (c-axle) is calibrated to the Surface Vertical with transmission window.Crystalline size is that 0.5 inch * 1mm of Φ is thick.Crystal is the UV level product that Ohyo Koken Kogyo company limited makes.Several such crystal can be with a collection of acquisition, and the crystal of use is according to crystalline quality and its surface condition coupling.Crystal after analyzing all and using in lamp is also use up any error that all effort are brought out to eliminate because with any variation in a collection of.

In experiment, the first step of work is with the outside surface 11 of optics microscopic by the light transmission window 8 of Φ 8mm central section transmission of ultraviolet light, to observe the material of the adherent any film shape of possibility.Then, wipe any adherent material off, can find that what adhere to outside surface 11 is the adhesive film of more weak material this moment with plastic tweezer.

Then, adhesion material is carried out ultimate analysis.Utilize EPMA (electronic probe X-ray microanalysis device) that the outside surface 11 of light transmission window 8 is carried out ultimate analysis (analysis condition: acceleration voltage 15kV, irradiation electric current 5E-8A, measuring method: quantitative analysis, explication de texte, image analysis).

The result who analyzes from EPMA can find, detects a large amount of carbon on the Φ 8mm central section of transmission of ultraviolet light.The circular ring type zone of the outside, Φ 8mm circle ring center district of transmission of ultraviolet light is at the shelter of flange 17, and the zone for there not being ultraviolet ray to pass through, but also detects the carbon that pollutes level in this circular ring type zone.The meaning of " pollute level " is the weak signal of the carbon detection that produces when analyzing whole clean surface in this EPMA analyzes.Therefore, producing this signal will have carbon to adhere to inevitably.Therefore, the measurement limit that is used for the EPMA of carbon is analyzed is determined by the Prevent Carbon Contamination level of Analytical equipment.When from the carbon signal level of Φ 8mm central section with pollute signal level relatively the time, find that the former is obviously high, determine to have taken place on the outside surface 11 of light transmission window the membranaceous fact of gathering of carbon.

As previously mentioned, with reference to the described equipment of Figure 14, the mechanism of coke build-up is to have organic gas in the vacuum zone 14, when these organic gass are absorbed on the outside surface 11 of light transmission window 8, when the vacuum ultraviolet ray is transmitted by light transmission window 8, organic gas transforms into carbon through dehydrogenation reaction, and accumulates on the outside surface 11.

Along with in above-mentioned environment, continuing to use light transmission window 8, along with the poly-continuation of carbon deposit, through reducing light transmittance after a while.Therefore, compare, need some mechanisms to eliminate this carbon that gathers from outside surface 11 with its original state.Because have been found that membranaceous gather of carbon on outside surface 11 is the major cause of light transmission window decay, therefore, the present invention continues to study counter-measure, it will cause following of the present invention finishing.

The present inventor is by following this problem that solved that experimental results show that.The starting material of carbon are organic gas, are impossible but in fact will eliminate them.In addition, if it not by uviolizing, dehydrogenation reaction can not take place, but such equipment will not have the effect as light emission equipment.The position of carbon laydown accurately is complementary with the position that vacuum ultraviolet ray shines.Vacuum ultraviolet ray directly excites organic gas impelling dehydrogenation reaction, but this high photon energy not only excites organic gas, and many molecules are also excited and become active condition.

With reference to the Fig. 1 as embodiment, light output equipment in this embodiment is the vacuum ultraviolet ray output that utilizes the 122nm wavelength of hydrogen light emission, and this vacuum ultraviolet photon energy is 10.2eV.This photon energy grade will excite oxygen, H ₂O gas (steam), and can produce group with strong oxidation capacity.Other composition in oxygen, carbonic acid gas, water vapor and the atmosphere keeps the former of vacuum zone 14 because will absorb vacuum ultraviolet ray and weaken its intensity.Therefore, eliminating absorbing medium by devices such as vacuum pumps is that Atmospheric components are to produce vacuum zone 14.

Yet, even these are the gaseous state composition, because it comprises O ₂, water vapor etc., can find, by suitably reducing its concentration (reducing its pressure), can produce group and can sharply not weaken vacuum ultraviolet ray with oxidation capacity.When the light output equipment is being worked under the condition of the adjustable gaseous constituent coexistence of concentration and when realize the vacuum zone 14 of follow-up phase, can eliminated the carbon on the outside surface 11 that sticks to light transmission window 8.In addition, also can eliminate and adhere to the carbon that is arranged in vacuum zone 14 all optical element surfaces.The reason that can eliminate carbon in this way is, the carbon on light transmission window 8 outside surfaces 11 adheres to carbon being decomposed and eliminate simultaneously and takes place, and group decomposes and the speed of eliminating carbon surpasses the speed of its formation.

Because the reaction that utilizes group to decompose carbon makes carbon be converted into volatilization molecule such as carbonic acid gas and water vapor, these can shift out from system fast with vacuum pump.The group of Chan Shenging is oxygen and the ozone that excites generation by oxygen molecule substantially in the case, and the OH base by exciting water vapor etc. to produce.

In addition, when the light output equipment is being worked under the condition that the adjustable gaseous constituent of these concentration exists and as the carbon laydown that is pre-existing in during in the outside surface 11 of light transmission window 8, to decompose and eliminate this carbon gradually, so that can eliminate all carbon fully at last, recover light transmission window 8 to its initial light transmittance.Then, operation light output equipment does not have the poly-optical element operation follow-up phase vacuum zone of carbon deposit and do not need to utilize, and just can eliminate carbon from these optical element surfaces that are positioned at vacuum zone 14.

Therefore; utilize conclusion of the present invention; can prevent the decay of light output equipment transmission window; so that do not reduce the light intensity that produces by described light output equipment; thereby make it not only can eliminate the maintenance cost relevant and the maintenance of equipment downtime with the replacing of light transmission window; but also can be formed on sedimentary carbon on light transmission window 8 or the optical element to eliminate by operation light output equipment; so that it returns to original state; thereby recover all performances in vacuum zone, so that keep vacuum zone 14 with less maintenance cost and frequency of maintenance.

Below, explanation is used for regulating the method for the concentration of vacuum zone 14 environment Atmospheric components.Gas is supplied with and can be used the purity oxygen of supplying with from oxygen canister.In addition, it can be drawn from air, maybe can use the blast main of installing in factory.Also can use the gas tank that is filled with dry air.Can also use oxygen in addition and as from the mixture of rare gas elementes such as the argon of gas tank allotment, helium.With the gas supply pressure that illustrates among the structure embodiment in the back can be by valve opening and gas tank purification vacuum district 14 and the ability of the pressure component of pilot-gas control.

Water vapor can also be increased in the above-mentioned gas, or only use water vapor.Water vapor increases according to the water in the preliminary sealed vessel and has the zone of filling saturated vapor, then, and by this water vapor is mixed with any of above-mentioned gas.When independent use, only need enter in the vacuum zone 14.The temperature of water can be room temperature, maybe can turn cold or heat.The pressure of water vapor temperature according to water under state of saturation changes, so can set the cleansing power of valve opening and pump, with the pressure component of water vapor in the control vacuum zone 14, this will illustrate among the structure embodiment in the back.

The pressure component of the above-mentioned gas in vacuum zone 14 is determined by following condition.The lower limit of gas partial pressure will according to by gas and the target that does not stop the pressure component of operation to absorb vacuum ultraviolet effect determine.For example, under actual conditions, if be oxygen, the upper limit is the grade (below 20mtorr) of 10mtorr (millitorr) substantially.If surpass the pressure component grade, then the vacuum ultraviolet (VUV) line absorption by oxygen will reach that very important point-it will begin to hinder the effect target of vacuum zone 14.Yet if the length of the opticpath by vacuum zone 14 is fully short, it can ignore the effect of oxygen concentration at large caps.Whether the accurate setting of higher limit can be determined by obstruction by pressure component filled vacuum district 14 and inspection effect target with the gas regulation.Specifically, vacuum ultraviolet amount can be used as research its attenuation degree means measure.

The lower limit of gas partial pressure should be set in more than the processing power that is used to the load that is about to apply.At this, the meaning of so-called " load " is the wavelength of the vacuum ultraviolet ray 9 that transmits when the type that exists by organic gas and concentration and by light transmission window 8 and intensity when determining, the gather speed of carbon on the outside surface 11 of light transmission window 8.The meaning of so-called " processing power " is that carbon is by the group decomposition that excites generation of vacuum ultraviolet ray gas and the speed of eliminating.

Inventor of the present invention has made various tests, the inventor faces the various situations of the vacuum zone 14 that is used for, the some of them situation is unknown, but, for example, by the conventional turbine molecular pump and utilize dried pump depletion system to produce the situation of vacuum zone 14, for example, the lower limit that is used for oxygen will be approximately 0.01 to 0.1mtorr.If the oxygen of this kind level exists, then will have enough processing poweies to load.Water vapor provides the processing power grade higher relatively than oxygen, and its actual lower limit. and will be in 0.005 to 0.01mtorr magnitude.

In order accurately to set this lower limit, can use oxygen filled vacuum district 14, be actually used in certain pressure component, the light output equipment can be by operating the analysis of any bur on the outside surface 11 of light transmission window 8 subsequently then.Suitable analytical procedure is included in the observation under the opticmicroscope or uses the carbon analysis of EPMA.Do not show that tangible carbon laydown exists as long as analyze, the pressure component that uses this moment can be determined can realize the decomposition of carbon fully and eliminate and handle.

Now, with the technique means that specifies according to the present invention's proposition of above-mentioned discovery.

A kind of equipment that can reach effect of the present invention that the present invention relates to according to claim 1 and 2.The invention provides a kind of being used for by being positioned at output light or preventing along the opticpath of described output light, suppress, or improve the decay of the optical property of optical system, improve the reliability of optical system optical property and the optical property recovery device in life-span, wherein said optical system is arranged in the nearly vacuum zone that organic composition can decompose, described decay is owing to deposit or accumulate in the irradiate light surface of described optical system, the light reflecting surface, the carbon on light emission surface (unified be called ' illumination surface ') and producing, described surface is in the face of described vacuum zone, described optical property restorer comprises: producing has nearly vacuum zone that active-energy the exists device with the oxidizing reaction that excites carbon, and described nearly vacuum zone is in the face of the described light illumination surface of described optical system; Produce the device of negative ion or group in described nearly vacuum zone; Promote described negative ion or group and the device of oxidizing reaction between the described carbon of described nearly vacuum zone; And wherein said optical property restorer is deposited on the carbon that gathers of described illumination surface by oxidizing reaction elimination or minimizing.

More particularly, it comprises: produce the device of nearly vacuum zone with the oxidizing reaction that excites carbon, described nearly vacuum zone is in the face of the described irradiate light surface of described optical system; Produce the device that contains Sauerstoffatom gas such as aqueous vapor body or oxide gas stream in described nearly vacuum zone; Provide active-energy so that at the described device that produces the oxidation of coal reaction between Sauerstoffatom gas and the carbon that contains in described nearly vacuum zone; And wherein said optical property restorer is deposited on the carbon that gathers of described illumination surface by oxidizing reaction elimination or minimizing.

Above-mentioned " near vacuum zone " can limit by the vacuum space of wherein high reactivity energy excitation oxidation of coal reaction, to pass through removing hydrogen the organic mixture to decompose carbon from hydrocarbon the grade.The pressure of nearly vacuum space fluctuates by the intensity and the above-mentioned Sauerstoffatom gas cyaniding ability that contains of active-energy, yet they must be below tens mtorr.

According to claim 3 the present invention relates to be used for by being positioned at output light or along the opticpath of described output light, be used to prevent, suppress or improve the decay of optical system optical property, the reliability of the optical property of improvement optical system and the optical property restoration methods in life-span, wherein said optical system is arranged on the nearly vacuum zone that organic composition can decompose, described decay is owing to deposit or accumulate in the irradiate light surface of described optical system, the light reflecting surface, the carbon on light emission surface (unified be called ' illumination surface ') and producing, described surface is in the face of described vacuum zone, and described optical property restoration methods comprises step: generation has the nearly vacuum zone of active-energy existence to excite the oxidizing reaction of carbon; Described nearly vacuum zone is in the face of the described light illumination surface of described optical system; Produce negative ion or group in described nearly vacuum zone; By making the reaction of negative ion or group and sedimentary carbon, elimination or minimizing accumulate in the carbon that gathers on the described illumination surface.

More particularly, the feature of present method embodies by following steps: produce nearly vacuum zone to excite the oxidizing reaction of the carbon of high reactivity energy excitation under existing, wherein said nearly vacuum zone is in the face of the described light surface of described optical system; And (for example providing the gas that contains Sauerstoffatom such as water vapor or oxidizing gas, water vapor, oxygen, hydrogen peroxide, ozone or its mixture and rare gas element (comprising air)) stream provides active-energy when entering into described nearly vacuum zone, thereby, eliminate or reduce the carbon that gathers that accumulates in described illumination surface by the carbon that gathers and the oxidizing reaction of the described active-energy that provides are provided.

In addition, above-mentioned optical system not only comprises the optical element of being made up of light transmission that is positioned at border, nearly vacuum zone or reflecting element, and comprise, and pass through the optics integral part that irradiation light surface-treated optics object is formed by the adjusting optical element that is positioned at diffraction, refraction, spectrum generation and transmission and diffraction along the vacuum zone opticpath.And other described optical system comprises position adjustments and maintaining body, container and the sealing member of described optical element or described optics object.

In addition, it is to have 380nm wavelength or following common ultraviolet ray that the present invention also is administered to the light beam that forms described opticpath effectively, or have 200nm wavelength or a following vacuum ultraviolet situation, exporting described ultraviolet ray or being positioned at along the described optical system of the opticpath of described output light is the optical material that comprises a kind of or mixture of fluorine cpd, as magnesium fluoride, Calcium Fluoride (Fluorspan), barium fluoride, aluminum fluoride, sodium aluminum fluoride, thiolate or other fluorine cpd, metal fluoride such as lanthanum fluoride, cadmium fluoride, neodymium fluoride, yttrium fluoride, or as the high-purity mangesium oxide thing of artificial quartz glass or sapphire.

In addition, under the carbon that is decomposed by the organic composition of described nearly vacuum zone had been grown in situation on described optical system and the apparent surface, the lower value of pressure component that is used to supply to the described gas that contains Sauerstoffatom of described nearly vacuum zone was preferably set to the level that surpasses whole coke build-up speed.In addition, when described vacuum ultraviolet ray shines described optical system or during from described irradiation optical system, under the situation that the described optical property of described optical system is recovered, the higher limit of pressure component that is used to supply to the described gas that contains Sauerstoffatom of described nearly vacuum zone is preferably set to the angle that is lower than the effect of playing from it in described nearly vacuum zone, can not unheeded level by the described vacuum ultraviolet effect of absorption that contains the gas of Sauerstoffatom.

The higher limit of pressure component that is used to contain the gas of Sauerstoffatom is preferably set to fills described nearly vacuum zone by reality and has and necessarily contain the Sauerstoffatom gas partial pressure, measures on described opticpath vacuum ultraviolet quantity then to detect the level of its attenuation degree.

In addition, when above-mentioned when containing Sauerstoffatom gas and being oxygen, scope is 0.02mtorr to 20mtorr (preferred 0.02mtorr is to 10mtorr) between the lower limit-upper limit of gas partial pressure, and when gas be that 0.01mtorr is to 10mtorr (preferably 0.01mtorr is to 1mtorr) during for water vapor.

In addition, when the light beam that is formed at above-mentioned opticpath had high photon energy and is the light beam of a branch of provision wavelengths in the vacuum ultraviolet ray wavelength region, the present invention also was effective.

That is,, just can produce negative ion or group, and not use independent energy source (for example, heat energy, plasma energy, electric energy etc.) by the gas that contains Sauerstoffatom as long as above-mentioned active-energy is the vacuum ultraviolet ray with high photon energy.Though the active ion base such as the OH that use patent documentation 3 to quote ^-And O ^-, but consider the target of cleaning, its pressure condition is different from defined terms in the reference.

Second preferred implementation

In addition, in second preferred implementation, will make a concrete analysis of the decay that light transmission window 8 inside (as internal surface 10) takes place.

In order to address the above problem, the present invention makes a concrete analysis of the decay of the light transmission window 8 made by fluoride materials.The device that uses as shown in figure 14, wherein light transmission window 8 exposes side by the plasma that O type circle is connected to flange 17.MgF ₂(magnesium fluoride) single crystal is used to make light transmission window 8.

As a result, find when after that the decay of light transmission window 8 transmissivities of being shone by vacuum ultraviolet ray is by MgF by the vacuum ultraviolet ray irradiation ₂The formation of oxide compound causes on crystal (tens nm the are thick) surface.The existence that can determine fluorine in tens nm are thick on plane of crystal the zone reduces.

In addition, measurement by spectral-transmission favtor may be present in the generation of color center on the light transmission window 8 and the relation between the light transmittance decay to observe any, can find, the major cause of light transmission window 8 decay is not the absorption of color center, but is to be created in the defective that fluorine and oxygen exist on the plane of crystal.

For this point, the present invention has advised the technical scheme that the following describes at above-mentioned discovery.

First suggestion of the present invention relates to by fluoridizing the optical system that material is formed; it is characterized in that going up in the irradiate light side (inboard) of described optical system at least forming protective membrane, to prevent the sur-face peeling of fluorine atom from described optical system with 2-20nm film thickness.

Difference between the present invention and the patent documentation 4 will be described now.Patent documentation 4 relates to and has mercury and be sealed in discharge lamp in its curved pipe.Present technique is attached to curved pipe inwall to 0.15 μ m protective membrane to prevent mercury by using 0.1 μ m such as aluminium.

On the other hand, the present invention relates to the vacuum ultraviolet ray scope, wherein 2nm is applied to the surface of vacuum ultraviolet ray irradiation to the very film of 20nm,, substitute the generation of the initial decay of optical property like this by coating to prevent peeling off of fluorine.

The reason of restriction 20nm or following film thickness is that if for thicker arbitrarily, it will absorb vacuum ultraviolet ray can not keep its point as the effect of optical element to it.

2nm or more on following being limited to need guarantee on plane of crystal evenly covered with protective film.Because SiO ₂Or Al ₂O ₃, MgO, TiO ₂, ZrO ₂Molecular diameter be close to 1nm, if coating is not the thickness of at least 2 molecules, it can not make uniform protective membrane to reach purpose of the present invention on the whole surface of crystalline.

When the thickness of film is enough, though purpose is the surface of protection optical system, because metal oxide such as SiO ₂Or Al ₂O ₃, MgO, TiO ₂, ZrO ₂Not the material that natural permission vacuum ultraviolet ray passes,, as shown in figure 13, thereby reduced the ultraviolet amount that passes basic material so the existence of this protective membrane can make and absorb vacuum ultraviolet ray in film.When the thick grade of 20nm, transmissivity is just without 10% of film.Not only the initial transmission under 10% produces a large amount of declines of the optical property of basic material; and when it can not play the class of attenuation of effect of optical system; to worry that ultraviolet absorption will make protective membrane itself descend, and heat will make it peel off or produce other harm from optical system surface.Therefore, 12nm or thickness still less, preferred 10nm or thickness still less will keep basic material to have 40% of optical property, even under the worst imaginary situation, also will keep optical property 10% or higher.Therefore, because ultraviolet absorption will not expect that the film thickness above 20nm plays the effect of perfect optical system.

In addition, the oxidation of Mg is along with the generation of peeling off of fluorine atom, so in optimal way, the irradiation side (inboard) in described optical system forms the SiO with 2-20nm film thickness at least ₂Or the protective membrane of metal oxide, preferred 2-12nm, 2-10nm more preferably, to prevent the sur-face peeling of fluorine atom from described optical system.

Adopt the solution of the present invention, can suppress peeling off and oxidation of above-mentioned optical system surface fluorine atom, thereby suppress the decay of the light transmittance of optical system.

The method that growth is arranged in gas phase; as steam precipitation, ion plating, can be used to form the CVD of thin protective film etc.; but it is ionic fluid splash method and plasma CVD method that film forms particularly preferred method, because this method can be along with the well-proportioned film thickness of concavo-convex generation that produces by the polished finish to optical system.

Alternative plan of the present invention relates to a kind of comprising and has the optical system that the isoionic fluorine cpd in the optical device that is placed in the inner area with plasma existence were faced and were exposed on the surface, and wherein the 2nm-20nm protective membrane of high anti-plasma material is formed at the described isoionic fluorine cpd surface that is exposed to.

This scheme can suppress the fluorine atom of above-mentioned optical system surface to be peeled off or oxidation, thereby suppresses because the decay of the light transmittance of the optical system that plasma ambient causes.

In the case, the said protection film metal oxide such as the SiO that can quote for said protection film ₂Or Al ₂O ₃, MgO, TiO ₂, ZrO ₂Any one.By form said protection film on optical system, wherein optical system is made up of the single crystal fluorine material with the crystal axis (c axle) along the irradiate light direction, and the vertical surface of described protective membrane is coated with SiO ₂Or metal oxide, therefore, because the initial decay of above-mentioned fluorine optical system is by the coating balance, so can prevent the decay that basic material is caused by the vacuum ultraviolet ray irradiation for a long time.

In addition, because the above-mentioned SiO that quotes ₂Or other metal oxide has the anti-plasma performance higher than fluorochemical; therefore; can suppress peeling off or the oxidation of atoms metal of fluorine; and because this is as oxide compound; the result; when the protective membrane of the optical system that is used for making, after its initial decay, can prevent the further decay that fertile material is caused by the vacuum ultraviolet ray irradiation for a long time by the fluorine material.

Third party's case of the present invention relates to the method for using this device, and it uses the optics of above-mentioned optical system, and it is characterized in that, in advance will be from SiO ₂Or Al ₂O ₃, MgO, TiO ₂, ZrO ₂The protective membrane of the 2nm-20nm of middle a kind of metal oxide of selecting is applied to optical system; wherein said film suppresses structural element from the sur-face peeling of basic material or the oxidation on basic material surface; As time goes on;, described optical system is attached to has in basic material by vacuum ultraviolet irradiation or plasma-exposed than the vacuum ultraviolet (VUV) line source of the higher photon energy of absorbing wavelength of described optical system basic material or the demand device in plasma light source.

According to the present invention; after the initial decay that causes owing to above-mentioned metal oxide protective membrane; can suppress because long-time because vacuum ultraviolet irradiation or be exposed to that the element from basic material that plasma causes breaks away from or the decay of the basic material that the oxidation on basic material surface causes by this film; its optics output that means basic material will be after operation at first begins; no longer further reduce; for example, it can prolong life-span of light transmission window of the speculum of above-mentioned light take-off equipment.So also prolonged the interval that is used between light transmission window or the speculum repair and replacement, thereby improved the operating rate of light take-off equipment and reduce its running cost.

In the case; because above-mentioned protection is touched as the means that can increase device lifetime; therefore; only need to use sufficient light output can be provided the light source with compensation because the initial decay of the optical system that above-mentioned metal oxide protective membrane causes, thereby can not reduce the light transmission (transmissivity, reflectivity) of total system.

Promptly; when optical system is coated with the decay of said protection film to suppress its long-time because vacuum ultraviolet ray irradiation or to cause in the face of plasma in advance; otherwise it will make element break away from or oxidation from its basic material for a long time, the initial decay that it needs the light output of supplementary device to be caused by said protection film with compensation.For example, at the light take-off equipment that is used for as the measuring light line source, by utilizing the above-mentioned optical system of carrying out coating at least in a side, for example cover optical delivery window or reflection windows, can obtain stable light output for a long time, and this light take-off equipment can be used to measure application and keep the stable light output speed that can not decay, so that the operation of stabilization control device and measurement susceptibility.

Description of drawings

Fig. 1 is the view that shows the microwave-excitation hydrogen UV-lamp structure of first embodiment that is used to illustrate first preferred implementation according to the present invention.

Fig. 2 is the view that shows the microwave-excitation hydrogen UV-lamp structure of second embodiment that is used to illustrate first preferred implementation according to the present invention.

Fig. 3 is the view that shows the microwave-excitation hydrogen UV-lamp structure of the 3rd embodiment that is used to illustrate first preferred implementation according to the present invention.

Fig. 4 is the view that shows the microwave-excitation hydrogen UV-lamp structure of the 4th embodiment that is used to illustrate first preferred implementation according to the present invention.

Fig. 5 is the view that shows the microwave-excitation hydrogen UV-lamp structure of the 5th embodiment that is used to illustrate first preferred implementation according to the present invention.

Fig. 6 is the view that shows the microwave-excitation hydrogen UV-lamp structure of the 6th embodiment that is used to illustrate first preferred implementation according to the present invention.

Fig. 7 is the EPMA analytical results that shows the carbon of the light transmission window that is used to adhere to first preferred implementation according to the present invention.

Fig. 8 is the sketch that shows the microwave-excitation hydrogen UV-lamp structure that is used to illustrate second preferred implementation according to the present invention.

Fig. 9 shows the graphic representation that the XPS depth profile before the light transmission window uses is measured that is used for protective membrane coating.

Figure 10 shows the graphic representation that the light transmission window uses XPS depth profile afterwards to measure that is used for protective membrane coating.

Figure 11 shows the graphic representation that the XPS depth profile before the light transmission window uses is measured that is used for protective membrane coating.

Figure 12 is the graphic representation that is used for light transmission window use XPS depth profile measurement afterwards after demonstration has the protective membrane coating.

Figure 13 is presented at the graphic representation that concerns between the light transmittance of its original state optical system and the various protective membrane thickness.

Figure 14 shows the graphic representation that excites the hydrogen UV-lamp according to the traditional microwave of prior art.

Embodiment

[first preferred implementation]

Below, with the present invention suppresses or the embodiment of first preferred implementation of the carbon bur of the outside surface 11 of elimination light transmission window 8 describes to being used for reference to the accompanying drawings, in addition, optical system inhibition or the adherent preferred implementation of elimination carbon that is used for from being positioned at vacuum zone 14 also will be described with reference to the accompanying drawings.

The present invention is not limited to these embodiment, and it also can be administered to by discharge effectively or add the lamp or the laser equipment of thermogenesis light.

Embodiment 1

Fig. 1 is the sketch that shows the microwave-excitation hydrogen UV-lamp structure of first embodiment that is used to illustrate first preferred implementation according to the present invention.

The keeper (flange) 17 that light transmission window 8 connects is a collar plate shape, and its center aims at the hole of discharge tube 1, and it comprises the opening that diameter is bigger than the internal diameter of discharge tube.Window flange 17 comprises O type ring recess so that produce sealing at the whole opening of light transmission window 8, also have the lid shape of hollow mounting rack 20, be used to adhere to its bolt hole, and be connected to discharge tube 1 so that with the O type ring recess of window flange 17 maintenance vacuum.

The internal structure of mounting rack 20 adopt the concentric(al) circles of two-stage and restriction be used to hold light transmission window 8 the space and by discharge tube 1 around the space.In the end around discharge tube 1, end face has cut becomes O type circle 13 remains on the position by pressure angle.Not shown screw thread also cuts into the external peripheral surface at this end, and the vacuum boundary that is used for discharge tube 1 forms on circular open by the fastening fixed cap 21 of sealing member that utilizes O type circle 13 to form.Window flange connector 17, mounting rack 20 and cover 21 and all make by metal; Generally, adopt oligosaprobic stainless steel or aluminium, but be not limited to these materials.

Below, will the operation of the microwave-excitation hydrogen UV-lamp of said structure be described.At first, the discharge gas from discharge tube 1 is supplied with opening 1, supplies with 20sccm with the hydrogen discharge gas of 1/100 dilution with helium.Discharge gas is discharged by the vacuum pump (not shown) by outlet 3.Be installed in valve (not shown) hole between exhaust outlet 3 and the vacuum pump by adjusting, can regulate the exhaust specific conductance to keep about 5 holders (665Pa) in the discharge tube 1.The reason that produces the discharge air-flow in the direction from light transmission window oral-lateral to discharge tube 1 is to reduce as far as possible owing to exporting the source of pollution of the material of generation in 1 at described window 8 by plasma discharging.

Then, with 2.45GHz, the microwave of 50W is supplied with junctor from microwave and is provided to microwave oscillator 4.Microwave both can provide continuously also and can intermittently provide, the setter (not shown) that is installed on the supply lead is connected to microwave power supply, and microwave oscillator can be used for regulating power supply and the microwave energy output between the load (plasma discharging) of the plasma discharging 7 that discharge tube 1 produces.The light of hydrogen atom irradiation 103nm that excites by plasma discharging 7 and the vacuum ultraviolet ray wavelength of 122nm.Because MgF ₂As the material of light transmission window 8, this will illustrate below, so 103nm light is by MgF ₂Absorb and have only the vacuum ultraviolet ray of 122nm wavelength to pass and enter vacuum zone 14 as output lamp wiring (vacuum ultraviolet ray) 9.

In the case, the opening that is used for the holding flange 17 of light transmission window 8 is Φ 8mm, thus output enter the vacuum zone be the optical throughput of Φ 8mm.

MgF ₂(magnesium fluoride) single crystal is used for light transmission window 8, and quartzy axis (c axle) is aimed at the surface perpendicular to the light transmission window.Crystalline size is that (Φ 12.7mm) * 1mm is thick for 0.5 inch of Φ.The UV level product that the crystal that uses is made as Ohyo Koken Kogyo company limited.Many such crystal can be classified it to mate its crystal mass and surface condition to eliminate the variation with possibility grade in a collection of, so that the effect of energy verification protective membrane with a collection of acquisition.

In addition, photorectifier 12 is positioned to receive as the lamp output light 9 of monitoring from the light work output device of described lamp.

Oxygen is supplied to the vacuum zone 14 of using following method, and adjustments of gas is to the pressure component of regulation simultaneously.

Oxygen canister 23 (being made by Japanese Sanso company) is filled with pure oxygen (purity 4N) and is connected to setter 22.When air pressure adjustment is arrived 0.1kg/cm ²After, regulate the hole of the variable leak valve 19 that connects by pipe 16c, gas passes the pipe 16b on the atmospheric side, advances by the sealing mechanism (not shown) then and the pipe 16a in 14 supply with into vacuum zone 14 from the vacuum zone.The amount of providing is close to 1sccm.Discharge by turbomolecular pump (velocity of discharge of 50L/min, model are TP-50, and Mitsubishi Jukogyo Kabushiki Kaisha, Mitsubishi Jukogyo Kabushiki Kaisha makes) vacuum zone 14, and be connected to dried pump (not shown) in the downstream.In the case, oxygen partial pressure power is stabilized in 1mtorr (1 millitorr) in the vacuum zone.Therefore, the condition pressure component that forms oxygen in the vacuum zone 14 is the grade of 1mtorr (below 10mtorr) at least.

Experiment is also carried out so that 5mtorr, 2mtorr and 0.1mtorr to be provided by regulating valve opening, but also will be explained below, and can eliminate carbon equally effectively.

The variable leak valve of mentioning in the above description is not the product of special requirement; It is only for realizing the mechanism of fine setting knothole, various these type of mechanisms that can adopt any title.

Secondly, photorectifier 12 is used to measure the variation of microwave-excitation hydrogen atom UV-lamp in the elapsed time from said structure.

Plasma discharging 7 is used to excite hydrogen atom to reach 90 hours (about 4 days) to produce vacuum ultraviolet ray.Then, as a comparison, revision test but oxygen is not provided promptly, is operated aforementioned turbomolecular pump to keep same environment (0.001mtorr), comparative result then.

The result shows, when when the lamp on period is supplied with oxygen, does not observe because the poly-decay of passing through the transmission of light transmission window that causes of carbon deposit.On the other hand, in the contrast situation, if initial light transmittance is decided to be 100%, then during the whole test since on light transmission window 8 deposition of carbon make transmissivity drop to 35%.

Fig. 1 has shown that observed mode with film is gathered and adherent carbon 15 in control test.When lamp has Oxygen Flow when work, the carbon 15 that is presented among Fig. 1 does not adhere to light transmission window 8.

After using, during with optics microscopic observation light transmission window 8, on the light transmission window 8 that uses the supply Oxygen Flow, do not find bur, but in the control sample, material sticks to the scope of the whole center Φ 8mm of vacuum ultraviolet ray transmission in the mode of film.Can find that membranaceous material adheres to outside surface 11 with more weak connection power by with the material of plastic tweezer scraping outside surface 11 with peel adhesion.

Secondly, bur is carried out ultimate analysis.Utilize EPMA (electron probe X-ray microanalyzer) that Japanese Danshi company makes that the outside surface 11 of the light transmission window 8 that is used to control sample is carried out ultimate analysis, analysis condition is: the acceleration voltage of 15Kv, the irradiation electric current of 5E-8A, measuring method: qualitative analysis, linear analysis, pattern analysis.The result shows, detects tangible carbon in the Φ 8mm zone, center of the outside surface 11 of the light transmission window of transmission of ultraviolet light.The center extra-regional annular region of Φ 8mm is in the shade of flange 17, therefore, for there not being the zone of transmission of ultraviolet light, though EPMA analyzes the class of pollution that has disclosed at this regional carbon, does not have tangible carbon to adhere at this." class of pollution " is for obtaining the weak signal grade of carbon when analyzing whole clean surface in EPMA analyzes.With the adhesion that the behavior of photon beam irradiation clean surface produces carbon inevitably, this level of signal is determined according to adherent carbon.Therefore, the class of pollution of analytical equipment itself has determined to be used for the following measurement limit that EPMA analyzes.When the level of signal relatively polluted, the level of signal of the center Φ 8mm scope of transmission of ultraviolet light is obviously high, and this finds to determine that carbon accumulates on the outside surface 11 of light transmission window in membranaceous mode.

Fig. 7 has shown the linear analysis result who utilizes the EPMA control test.The unit of transverse axis is a millimeter in Fig. 7, and it represents MgF ₂Analysis position on the crystal diameter; Linear analysis on the described crystal is carried out from side to side.

Z-axis is illustrated in spectrum and produces the carbon signal intensity that crystal LDE2 detects.Main analyzing conclusions is listed in the outside of Fig. 7 chart.

Can find clearly, the carbon of obvious high signal intensity is arranged in the Φ 8mm zone by transmission of ultraviolet light from Fig. 7, it has clearly illustrated that the membranaceous adhesion in Φ 8mm zone, center.

On the other hand, after lamp is worked, do not detect the carbon signal that obviously surpasses the class of pollution from the surface of light transmission window under Oxygen Flow.

As mentioned above, under supply oxygen, work, can prevent or suppress carbon gathering on light transmission window 8 by lamp.

The realization of this scheme can suppress the decline by the transmissivity of light transmission window, thereby reduces the maintenance operation cost of changing window and the operation stop time of reducing lamp.

As embodiment, but present embodiment also can be administered to the equipment that uses light reflecting mirror (window) to this embodiment equally with the light transmission window.The embodiment of this light reflecting mirror has the speculum of using laser oscillator and light focusing mirror.Following embodiment can be adapted to the situation of light reflecting mirror too.

Embodiment 2

Fig. 2 is the sketch that shows the microwave-excitation hydrogen UV-lamp of second embodiment that is used to illustrate first preferred implementation according to the present invention.Other and embodiment 1 explanation are described in detail in this omission with spline structure and operating component.The specification of light transmission window 8 is the same with embodiment 1 explanation.In addition, photorectifier 12 is positioned to export with the light of receiving light emission light 9 as the light work output device of the described lamp of monitoring.

Utilize following method that water vapor is supplied to vacuum zone 14, and be adjusted to the gas partial pressure of regulation.The Glass tubing 24 (the pipe diameter is Φ 6mm) that is filled with 1mL water 25 (for distillation, ion exchange treatment and filtering pure water) is connected with pipe 16d by flange 17.The sealing structure Glass tubing of the flange 17 of combination O type circle with isolated from atmosphere, all Atmospheric components are all discharged from pipe in advance.Water 25 remains on room temperature (25 °), and internal vapor pressure is 25 holders (calculated value).This vapor pressure is supplied with as main steam pressure by pipe 16d, and behind the hole of regulating variable leak valve 19, it passes the pipe 16b of atmospheric side by the sealing mechanism (not shown), and 16a enters vacuum zone 14 by pipe.The amount of supplying with is near 0.1sccm.Discharge by the turbomolecular pump emptying (intestine evacuation velocity 50L/min, model are TP-50, and Mitsubishi Jukogyo Kabushiki Kaisha, Mitsubishi Jukogyo Kabushiki Kaisha makes) and the dried pump (not shown) in downstream vacuum zone 14.In the case, partial pressure of water vapor is stabilized in the vacuum zone of 0.1mtorr (0.1 millitorr).Therefore, condition is the vacuum zone 14 that partial pressure of water vapor is at least 0.1mtorr (below 10 millitorrs) grade.

Experiment also adopts the partial pressure of water vapor of 1mtorr and 0.1mtorr to carry out, and it realizes that by regulating valve opening this will be explained below, and can eliminate carbon equally effectively.

Secondly, measuring the light amount of being exported by above-mentioned microwave-excitation hydrogen UV-lamp with photorectifier 12 measures over time.

At first, hydrogen atom excites to produce the vacuum ultraviolet ray of 90 hours (about 4 days) by plasma discharging 7.Secondly, operating light under the situation that water vapor is not provided promptly, utilizes above-mentioned turbomolecular pump to test to keep the pressure environment of 0.001mtorr, compares two test-results then.

The result shows, during operating light, owing to find to form carbon, therefore, can not make the transmission attenuation of passing light transmission window 8 under the water vapor condition is being provided.On the other hand, in control test, if the beginning transmissivity of light transmission is 100%, then the bur of carbon makes transmissivity drop to 35% during whole measurement.

The carbon 15 that shows in Fig. 2 has shown the membranaceous adhesion of the carbon that observes in contrast, but when lamp operating period supply water vapor, then as shown in Figure 2, does not have the adhesion of carbon 15 on the light transmission window 8.

After lamp uses, when utilizing the outside surface of opticmicroscope viewing ray transmission window 8, when lamp operating period supply water vapor, do not find that used window has bur, but on the contrast window, transmit Φ 8mm zone, vacuum ultraviolet center and shown with the adherent material of membranaceous form.When utilizing plastic tweezer to peel off outside surface 11, can peel off coherent substance, can find, adhere to the more weak membranaceous material that adheres to that is of outside surface 11.

At this moment, coherent substance is carried out ultimate analysis.Situation about explaining among result by the EPMA ultimate analysis and the embodiment 1 is similar.

Specify owing to above, so, when water vapor is supplied with operating light, can determine, can prevent or suppress the adhesion of carbon to the light transmission window.

This method can suppress the decline of the light transmittance of light transmission window, thereby reduces and the relevant maintenance cost of window displacement, and reduces because the shutdown operation that maintenance causes.

Embodiment 3

Fig. 3 is the sketch that shows the microwave-excitation hydrogen UV-lamp of the 3rd embodiment that is used to illustrate first preferred implementation according to the present invention.Other and embodiment 1 illustrate that same structure and operating component are described in detail in this omission.The specification of light transmission window 8 is the same with embodiment 1 explanation.In addition, the photorectifier 12 as the described lamp wiring work output device of monitoring is positioned to export with the light of receiving light emission light 9.

Utilize the method for following provisions Atmospheric components to be supplied to vacuum zone 14 and regulate its gas partial pressure to regulation.

When by behind variable leak valve 19 adjustment holes, allow Atmospheric components to supply to vacuum zone 14 by being open to Atmospheric components, and pass the sealing mechanism (not shown) and enter vacuum zone 14 by pipe 16a by the atmospheric pipe of pipe 16b mobile.Feed rate is close to 1sccm.Discharge by the turbomolecular pump emptying (intestine evacuation velocity 50L/min, model are TP-50, and Mitsubishi Jukogyo Kabushiki Kaisha, Mitsubishi Jukogyo Kabushiki Kaisha makes, and is not shown in the drawings) and the dried pump (not shown) in downstream vacuum zone 14.In the case, Atmospheric components are in the vacuum zone inner equilibrium of 1mtorr (1 millitorr).Therefore, condition is at least the vacuum zone 14 of 1mtorr (having only 0.2mtorr oxygen) grade for the Atmospheric components pressure component.

Regulate valve opening to produce the pressure component of 0.1mtorr (having only 0.02mtorr oxygen), this will be explained below, and can eliminate carbon effectively equally.

Secondly, adopt photorectifier 12 to export over time with the microwave-excitation hydrogen UV-lamp operating period light that measurement has said structure.

At first, hydrogen atom excites by plasma discharging 7, and produces the vacuum ultraviolet ray of 90 hours (about 4 days).Secondly, as a comparison, do not provide Atmospheric components during operation, above-mentioned turbomolecular pump is used to produce the pressure environment of 0.001mtorr, compares two test-results then.

Under being provided, atmospheric condition during operating light,, therefore, can not make the light transmission decay of passing light transmission window 8 owing to find to form carbon.Yet in control test, the formation of carbon makes the light transmission by light transmission window 8 drop to 35% transmissivity from initial value 100%.

The carbon 15 that shows in Fig. 3 has reflected the membranaceous adhesion of the carbon that observes in control, but when lamp operating period supply Atmospheric components, does not then have the adhesion of carbon 15 on light transmission window 8 as shown in Figure 3.

After lamp uses, when utilizing the outside surface of opticmicroscope viewing ray transmission window 8, Atmospheric components are being supplied with water vapor simultaneously, do not find that used window has bur, but on the contrast window, transmit Φ 8mm zone, vacuum ultraviolet center and shown with the adherent material of membranaceous form.When utilizing plastic tweezer to peel off outside surface 11, can peel off coherent substance, can find, adhere to the more weak membranaceous material that adheres to that is of outside surface 11.

On this aspect, coherent substance is carried out ultimate analysis.1 name of results of elemental analyses and embodiment of being undertaken by EPMA identical.

Owing to abovely specify, so, when the supply operating light of Atmospheric components, can determine, can prevent or suppress the adhesion of carbon to the light transmission window.

This method can suppress the decline of the light transmittance of light transmission window, thereby reduces and the relevant maintenance cost of window displacement, and reduces because the shutdown operation that maintenance causes.

Embodiment 4

Fig. 4 is the topology view that shows the microwave-excitation hydrogen UV-lamp of the present invention's first preferred implementation the 4th embodiment that is used to illustrate, wherein will illustrate to be used to eliminate because output light adheres to the method for the optical system that is positioned at vacuum zone 14.Other and embodiment 1 explanation are described in detail in this omission with spline structure and operating component.The specification of light transmission window 8 is the same with embodiment 1 explanation.

Optical element among Fig. 4 is orientated as by 9 irradiations of lamp emission light.In the time of in organic gas is present in vacuum zone 14, carbon 15 has adhered to the both sides of optical element 27, and its irradiation by the optical element 27 of vacuum ultraviolet ray 9 produces.Because the adhesion of carbon 15, the transmissivity of optical element 27 descends and needs repairing.The reason that optical element 27 has reached this state is that lamp operates at vacuum state always.

Be used for vacuum ultraviolet interference filter is used to illustrate carbon as the example of optical element 27 elimination in this employing.Be used for vacuum ultraviolet interference filter by MgF ₂Substrate and multi-layer optical film coating are in its surface formed.This is to be used for for example traditional structure of interference filter of optical element.Because it allows the light of provision wavelengths section to pass through, therefore, this interference filter plays the effect of bandpass filter, but when carbon 15 adhered to its surface, its transmissivity was along with interference filter descends, and therefore the effect as optical element descends.Therefore, at the certain phase that reduces transmissivity, need or elimination carbon or replacing interference filter.On the whole, owing to for example have the meticulous characteristic of optical filter of the interference filter of blooming coating, be difficult to clean them.Cleaning may change the character of blooming, and is easy to because the scraping during cleaning causes defective.Therefore, there is not utilizable effective purging method, so must select renewal part.Yet, generally, because interference filter is expensive part, so cost becomes a problem.In embodiment 4, for verification efficient of the present invention, dropped to 50% (initial value) at the situation operating light that does not have gas to supply with up to the transmissivity of interfering grade from 100%, with have a mind to reduce transmissivity half, then optical element is positioned in the vacuum zone 14.

The method of embodiment 1 is used for pressure component at vacuum zone 14 oxygen and remains under the 1mtorr condition oxygen is supplied in the vacuum zone 14.Test to reach 10mtorr, 5mtorr, 2mtorr, 0.1mtorr and 0.05mtorr by regulating valve opening, this will illustrate below that this has same effect in carbon is eliminated.

Secondly, plasma discharging is used to excite hydrogen atom so that 90 hours (about 4 days) of vacuum ultraviolet ray emission.When supplying with oxygen during operation, will eliminate adherent carbon 15 from the surface of optical element 27, the transmissivity of optical element 27 almost returns to its original state.When viewing optics element under opticmicroscope surperficial, do not observe bur.

As mentioned above, can be by operating supplying with under the condition of oxygen, adhere to carbon on the optical element 27 with removing.

This method can suppress the decline of the light transmittance of optical element, changes relevant maintenance cost thereby reduce with optical element, and reduces because the shutdown operation that maintenance causes.

Embodiment 5

Fig. 5 is the view that shows the microwave-excitation hydrogen UV-lamp structure that is used to illustrate first preferred implementation the 5th embodiment according to the present invention.Wherein will illustrate because the elimination that adheres to the carbon that is arranged in vacuum zone 14 optical elements of using the lamp wiring emission to cause.Other and embodiment 1 explanation are described in detail in this omission with spline structure and operating component.The specification of light transmission window 8 is the same with embodiment 1 explanation.

In Fig. 5, optical element 27 is orientated the light emission of receiving light 9 as.Because use is identical among other element and the embodiment 4, so the explanation of other optical element is omitted at this.

In embodiment 5, effect for verification validity of the present invention, at the situation operating light that does not have gas to supply with up to the transmissivity of interfering grade 50% (the initial value) that descended from 100%, with have a mind to reduce transmissivity half, then optical element 27 is positioned in the vacuum zone 14.

The method of embodiment 2 is used for that water vapor is supplied to pressure component at vacuum zone 14 oxygen and remains in the vacuum zone 14 under the 1mtorr condition.Is that 5mtorr, 2mtorr, 0.01mtorr and 0.005mtorr test by regulating valve opening to reach partial pressure of water vapor, and this will illustrate below that this has same effect in carbon is eliminated.

Then, plasma discharging is used to excite hydrogen atom so that 90 hours (about 4 days) of vacuum ultraviolet ray emission.When at lamp operating period supply water vapor, will eliminate adherent carbon 15 from the surface of optical element 27, the transmissivity of optical element 27 almost returns to its original state.When viewing optics element under opticmicroscope surperficial, do not find bur.

As mentioned above, can be by operating supplying with under the condition of water vapor, adhere to carbon 15 on the optical element 27 with removing.

This method can suppress the decline of the light transmittance of optical element, changes relevant maintenance cost thereby reduce with optical element, and reduces because the shutdown operation that maintenance causes.

Embodiment 6

Fig. 6 is the view that shows the microwave-excitation hydrogen UV-lamp structure of the 6th embodiment that is used to illustrate first preferred implementation according to the present invention, wherein will illustrate because the use lamp wiring is launched the elimination that is arranged in the carbon on 14 optical elements of vacuum zone that adheres to that causes.Other and embodiment 1 explanation are described in detail in this omission with spline structure and operating component.The specification of light transmission window 8 with

It is the same that embodiment 1 illustrates.

In Fig. 6, optical element 27 is orientated the light emission of receiving light 9 as.Because use is identical among other element and the embodiment 4, so the explanation of other optical element is omitted at this.

In embodiment 6, effect for verification validity of the present invention, at the situation operating light that does not have gas to supply with up to the transmissivity of interfering grade 50% (the initial value) that descended from 100%, with have a mind to reduce transmissivity half, locate optical element 27 then in vacuum zone 14.

The method of embodiment 3 is used for pressure component in vacuum zone 14 Atmospheric components and remains under the 1mtorr condition Atmospheric components are supplied in the vacuum zone 14.

By regulating valve opening so that the pressure component of Atmospheric components reaches 2mtorr and 0.1mtorr tests, this will illustrate below that this can obtain same effect in carbon is eliminated.

Secondly, plasma discharging is used to excite hydrogen atom so that 90 hours (about 4 days) of vacuum ultraviolet ray emission.When in lamp operating period supply Atmospheric components, will eliminate adherent carbon 15 from the surface of optical element 27, the transmissivity of optical element 27 almost returns to its original state.When viewing optics element under opticmicroscope surperficial, do not find bur.

As mentioned above, can be by operating supplying with under the condition of Atmospheric components, adhere to carbon 15 on the optical element 27 with removing.This method can realize the recovery of the optical element of degradation, changes relevant maintenance cost thereby reduce with optical element, and reduces because the shutdown operation that maintenance causes.

[second preferred implementation]

Below, will describe the present invention's second preferred implementation with reference to the accompanying drawings, wherein, protective membrane is covered on the light transmission window in order to prevent or suppress the decay of window.Yet the present invention is not limited to this kind structure, and it also can be applied to naturally by discharge or thermogenesis alight, and the laser equipment that can be suitable for.

Fig. 8 is the sketch that shows microwave-excitation hydrogen UV-lamp; It is used to illustrate embodiments of the present invention 1-3.The flange 17 that is used for light transmission window 8 is collar plate shape, and its center aims at the hole line of discharge tube 1, and is included as the diameter opening bigger than the diameter of discharge tube.Window flange 17 comprises mounting rack 20 O type ring recess 13b that is made as the device of sealing light transmission window 8 on the above-mentioned opening and the hollow that comprises the bolt hole that is used to be connected, the lid shape, and the O type ring recess 13a that is used to connect discharge tube 1, it can also make flange 17 to keep vacuum.

The inner surface structure of mounting rack 20 is made up of the concentric hollow cylinder of spatial two-stage that surrounds to holding light transmission window 8 and discharge tube 1.Encasing on the discharge tube 1 lateral end surfaces is O type circle 13c, and it is installed in the cutting on the cross bevel of corresponding loop diameter.In addition, also cut the screw thread (not shown) at the external peripheral surface of this end, so that cylindrical opening end cap 21 is installed, it keeps O type ring recess 13c on its position and limit the vacuum boundary of discharge tube 1.Window flange 17, mounting rack 20 and cover 21 and all make by metal; Generally, adopt oligosaprobic stainless steel or aluminium, but material is not limited to these metals.

Below, the operation that explanation is had the microwave-excitation hydrogen UV-lamp of said structure.At first, the hydrogen that carries out 1/100 dilution in the helium is supplied with opening 2 by discharge gas and supply to discharge tube 1 with the speed of about 20sccm.Discharge gas is discharged by the vacuum pump (not shown) by exhaust outlet 3, and the adjusting control exhaust conductivity in the valve (not shown) hole between exhaust outlet 3 and vacuum pump is to keep discharge tube 1 interior approximately 5torr (665Pa).Be to discharge tube 1 mobile reason that in light transmission window 8 any material that is produced by plasma 7 is all discharged in the direction away from light transmission window 8 as far as possible, so that reduce the source of pollution of described window 8 in discharge tube 1.

Microwave oscillator tuner 18 is a round tube type, and it is the structural element of the microwave oscillator that can regulate the microwave electromagnetic field distribution in the microwave oscillator, and its internal diameter is the housing of discharge tube 1.In addition, its structure is so that it can insert, and its end surfaces with microwave oscillator 4 is axially aligning simultaneously, and it can be in the electric conductivity of maintenance simultaneously with microwave oscillator 4 that endwisely slip.Tuner 18 is formed by copper or brass, and same material also is used for microwave oscillator 4.The microwave electromagnetic field distribution is regulated in acting as of described tuner 18, and its degree of depth according to its insertion produces plasma body 7 so that the generation of microwave concentrates on center 6.

Then, with 2.45GHz, the microwave of 50W is supplied with junctor from microwave and is supplied to microwave oscillator 4.The supply of microwave both can be continuously also can be intermittently, the setter (not shown) is installed in the centre of the power transmission line that microwave power supply is connected with microwave oscillator.It can be conditioned the microwave energy between control power supply and the load (plasma discharging), so that produce plasma discharging 7 in discharge tube 1.The hydrogen atom that excites by plasma discharging 7 produces the vacuum ultraviolet (VUV) Line beam of 103nm and 122nm wavelength; They pass light transmission window 8 and make the light 9 of irradiation light be transferred to the outside.

MgF ₂(magnesium fluoride) single crystal is used to make light transmission window 8, and its crystal axis (c axle) aligned perpendicular is in the surface of light transmission window.

Before light transmission window 8 is installed in position shown in Figure 8, applied Al in advance ₂O ₃The film coating conduct of (aluminium) is to the protective membrane 10A on the surface 10 of light transmission window 8.Adopt ion beam sputtering type film forming method film to form and apply coating.

Below the ion beaming film forming method will be described.The Ar compression ring border that remains 0.1Pa pressure is used for film and forms gas, bombards the sintering Al of 3 inches of φ with the Ar ion-accelerating voltage of 20Kv ₂O ₃Target electrode (purity 4N) is with from target electrode sputter Al ₂O ₃To the surface 10 of light transmission window 8 to produce film.The calibration curve that concerns between variable quantity by prior generation explanation quartz crystal vibration quantity and the film thickness utilizes quartz (controlled) oscillator that film thickness is controlled.By the way, can be by correspondingly changing duration of oscillation to form required thickness.

The coating method that is used to produce protective membrane 10A is not limited to above-mentioned ion beam sputtering film forming method.Also can produce the film of required composition by selecting appropriate means and device.Other possible method comprises the gas phase process as vapor deposition, ion plating, CVD etc.

The scope that is used for the suitable film thickness of protective membrane 10A is determined according to the transmission that optical system surface coverage condition and 122nm vacuum ultraviolet ray require.

Figure 13 shows to work as Al ₂O ₃When using, compare the graphic representation that changes between light transmission and the protective membrane thickness with the original state that does not have coating to exist as light transmission window coating.As shown in figure 13, the degree of optical system transmissivity is along with its original state descends for the protective membrane thickness function increases.Preferably adopt the thinnest film that can suppress its initial decay.On the other hand, effective in order to make protective membrane, must cover all surfaces of optical system.On the whole, in the starting stage of its application, film is not uniform membrane structure, and it forms island structure so that the part optical surface exposes at optical surface, does not still reach effective protective membrane.

After protective membrane formed, with AFM (application of force microscope automatically) observation surface, it demonstrated in order to form flat smooth film, and the film thickness that need cover substrate is 2nm or bigger.

In addition,, consider fully thick 20nm or thicker film thickness, can find, adopt SiO from the purpose on the surface of protecting optical system effectively ₂Or Al ₂O ₃, MgO, TiO ₂, ZrO ₂Protective membrane because vacuum ultraviolet high-absorbable, use the feature of the optical system of protective membrane to be attenuated in fact thereon, protective membrane itself absorbs the decay that produces and hotly can make it peel off or produce the problem of other optical system surface.Because this vacuum ultraviolet absorption causes optical system can not play the effect of expection, so the upper limit of film thickness is set at 20nm or bigger, preferred 12nm or bigger, or 10nm or bigger more preferably.

In the present embodiment, adopt the protective membrane thickness of 6nm, under this protective membrane thickness, the transmissivity of 122nm wavelength light is 50% of the given original state of not using protective membrane 100% transmissivity.

In addition, photorectifier 12 is positioned to launch light 9 as the light take-off equipment of the described lamp of monitoring with receiving light.

Secondly, photorectifier 12 is used for measuring any variation of light work output of the hydrogen UV-lamp of the microwave-excitation with said structure.

At first, hydrogen atom excites by plasma 7 and produce light in the vacuum ultraviolet ray wavelength region and reaches 90 hours (about 4 days).Secondly, as a comparison, light transmission window 8 usefulness do not have the light transmission window of protective membrane to replace, and revision test and comparative result.

Use following evaluation method.The initial transmission of light transmission window is T ₁(under the situation of control test, T ₀=T ₁), after using, that is, after 90 hours, the transmissivity of reduction is T ₂, calculate the transmissivity Δ T[% of variation then]:

Δ T=(T ₁-T ₂)/90 formula (1)

In addition, velocity of variation is expressed as rate of fall-off K[%/hr.], with following formula definition.

K=100 Δ T/T ₀Formula (2)

By comparing the size of rate of fall-off K, can quantize and estimate the decay of light transmission window 8 apace.Obviously, the K value is low more, and the decay of light transmission window is slight more, and its life-span is long more, and its frequency that need change is more little.

The result shows, as protective membrane (Al ₂O ₃) when being used on the light transmission window 8, rate of fall-off K is 0.04%/hr..On the other hand, being used for correlated rate of fall-off K is 0.46%/hr., is approximately 11 times of coating window.According to this evaluation, we find, compare with not using coating, and the protective membrane 10A on light transmission window 8 has obtained the life-span and improved about 10 factor.

In order to illustrate the influence of protective membrane 10A, will illustrate that below coating has Al before the use and using afterwards in lamp ₂O ₃As the XPS surface analysis result of the light transmission window of protective membrane 10A, and as a comparison, before explanation used in lamp and after using, do not have a surface analysis result of the light transmission window of protective membrane.

Fig. 9 shows correlated before use analytical results.Transverse axis is the time of argon, and its amount is proportional to sputter depth.The sputtering time zero minutes is illustrated in the original state before the sputter, the analysis of its corresponding plane of crystal.In the XPS aggregate analysis, the natural pollution of the message reflection material that original state obtains detects and is the absorption composition to carbon, oxygen etc.Yet,, therefore can from analytical data, be omitted owing to have virtually no thing.Z-axis is represented the ratio by the various elements of XPS discovery.

Fig. 9 is presented at before the use, and the contrast window does not have the fluorine loss at all.Though find the oxygen of trace on the surface, in crystal, do not find any material of depositing within it.Naturally the oxygen that absorbs the surface in the polluting material is the result owing to the argon sputter, and the argon sputter is ordered about it and entered into crystal.Therefore, no matter aerobic or anaerobic exist in crystal, and the amount of oxygen that is presented among Fig. 9 is construed as the trace that be used for as the calibration basis of other analytical results.

Figure 10 shows the comparative analysis result who uses behind the protective membrane.Figure 10 clearly illustrates that the loss of fluorine from the control sample surfaces.In crystal, find that with the same degree of depth of fluorine deficiency layer a large amount of oxygen exist simultaneously.Therefore, in the control sample after use, upper layer demonstrates fluorine deficiency and oxidation.This condition of surface is the major cause that 122nm microwave vacuum ultraviolet transmittance is reduced.

Secondly, Al ₂O ₃Protective membrane 10A be applied on the light transmission window 8 thickly near 5nm, and Figure 11 shows its analytical results before being used.The description and interpretation of graph-coordinate axle are identical with Fig. 9, no longer illustrate at this.The Al of one of protective membrane composition (aluminium) newly is added among the figure.Figure 11 has shown that the synchronizing pattern of fluorine and magnesium extends from the surface to inside, the synchronizing pattern of oxygen and aluminium extends from the upper layer to inside.Therefore, although covered with protective film is several nm from the fluorine of upper layer detection and the former resolving power because of XPS analysis of XPS analysis of magnesium signal at depth direction.Therefore, distribute even attempt to measure the ideal border, because the width of resolving power is wide inevitably in shape, therefore, it can not be presented on the figure as step.In addition, consider the protective membrane thickness of 5nm, if the MgF of substrate was not then carried out in sputter about 20 minutes ₂Crystal exposes maintenance.This is because Al ₂O ₃And MgF ₂Between the difference of sputtering yield cause.Concentrate on this point, be appreciated that F and Mg, O and the synchronous zone of Al figure.

At last, Figure 12 demonstrates at it and uses coating that about 6nm Al as protective membrane is arranged ₂O ₃Analytical results behind the light transmission window of thickness.The description and interpretation of graph-coordinate axle are identical with Fig. 9, no longer illustrate at this.Figure 12 has shown that the figure of oxygen and aluminium is synchronously from the surface to inside.In addition, do not confirm to exist at the crystals aerobic.This just can clearly be seen that, has prevented that by protective membrane oxygen from entering into crystalline inside.

On the other hand, asynchronous from the surface with the figure of fluorine that enters into the center and magnesium.Can clearly be seen that fluorine has entered into the Al of protective membrane 10A ₂O ₃In.Yet, because the existence of protective membrane 10A though fluorine is present in the inside of protective membrane, but still is not got rid of fluorine fully to produce fluorine deficiency, under correlated situation, expect at an easy rate oxygen as an alternative thing by its mechanism that enters.In fact, if consider not have among Figure 12 the situation of protective membrane, can utilize Figure 10 to be easy to illustrate the formation of above-mentioned fluorine deficiency layer and zone of oxidation.

As above illustrate; by utilization protective membrane 10A as coating on light transmission window 8; can suppress the generation of fluorine deficiency layer; and in crystal, prevent or suppress the existence of oxygen (zone of oxidation); in addition; when with comparative group relatively the time, the light transmission window with protective membrane coating forms the rate of decay K that descends with about 10 coefficient.

In addition, when using SiO ₂Coating (film thickness 6nm) is during as the protective membrane of light transmission window 8, and rate of decay K is 0.06%/hr..On the other hand, the rate of decay K of comparative group is 0.46%/hr..Even this just can confirm to use SiO in protective membrane ₂, also can reach same degree of protection, can be in the real about 8 times improvement of rate of decay K.

In addition, as using Al ₂O ₃The same, also can use metal oxide such as MgO, TiO ₂, ZrO ₂As the material of protective membrane, it demonstrates still less variable color than fluorine cpd under uviolizing.

As mentioned above; optical system according to the present invention has protective membrane formed thereon; the optical property that does not have protective membrane of itself (for example, if it is the light transmission window, it will be light transmittance) is lower than the optical property that it is arranged on pre-coated layer state.Yet it is unfavorable estimating those optical systems separately, is important with them as being combined into whole part evaluation as the light take-off equipment that uses an optics take-off equipment part.Promptly, can compensate the initial inferior position of the optical system in the above-mentioned optics take-off equipment, and configuration light outputs to the specification that system needs, it can be realized keeping the output of optics take-off equipment and increase its life-span, thereby reaches the purpose of the overall light take-off equipment that descends such as frequency of maintenance that its light output window is provided and maintenance cost.

In addition, the present invention is used for be highly profitable as light source in the measurement application scenario.Example wherein is secular monitoring or the similarly application such as generation of carrying out environmental pollutants.On the whole, when adopting this to measure, in measurement the degree of signal and sensitivity be proportional to light output square.As mentioned above, in the prior art, the measurement sensitivity of light source improves by optical pressure output, but the final decay of optical system makes it must suppress to reduce light output and measures the decay that sensitivity reduces.The optical system that the present invention uses prolongs the life-span of light take-off equipment, and the more stable output performance of long-term maintenance, to address the above problem and to provide the light take-off equipment that is suitable for the long-range circumstances monitoring.

More than the embodiment of Shi Xianing is used for the light transmission window, but also can be applied to the device that uses light reflecting mirror (window).The embodiment of this light reflecting mirror is the condensing lens that is used for the speculum of laser oscillator and is used for lamp.Therefore, light reflecting mirror can be used for same Application Example.

As described above, the present invention can prevent or suppress owing to reduce the optical system decay that the coke build-up of transmissivity causes, and definite said system and optical element life-span, thereby reduce the maintenance operation frequency of changing optical system, and when using optical element such as light transmission in system, refraction, reflection, spectrum produces, during a kind of the or combination of the optical effect of interfering, reduce the running cost that uses as the various optical devices of conventional ultraviolet ray or vacuum ultraviolet high photon energy light, for example, when the optical element of described transmission or reflection is positioned at border, nearly vacuum zone, wherein decomposable organic composition can make optical element continue to use in diffraction, refraction, spectrum produces, optical path produces decay in the vacuum zone of transmission, the analysis position that perhaps comprises container is regulated optical element or other surface or sealing substance through exposure, the position adjustments equipment of regulating optical element is present in wherein, for example is used to have vacuum ultraviolet exposure sources (stepper) and autochromatic plate.

Specifically,, can prevent or suppress the decay of described optical system by preventing or suppress the decline of carbon light transmittance in the optical system that its surface sediment produces, thus the maintenance operation frequency of reduction replacing optical system etc., and reduce running cost.

In addition, by preventing or suppress carbon accumulation along the irradiating surface and the emitting surface of opticpath in the vacuum zone in optical system, can prolong the life-span of upstream device and improve the reliability of equipment.

Specifically, the optical transmittance that the accumulation of carbon on light transmission window and other optical element causes because the present invention can prevent or suppress descends, therefore, can prolong need be to cleaning such as light transmission window or the maintenance intervals of changing, thereby helps to improve the operating rate of equipment and reduce maintenance cost.

In addition, by preventing or suppress optical element and the irradiating surface of optical system and the accumulation of emitting surface of carbon, can prolong the life-span of upstream device and improve the reliability of equipment in the vacuum zone that is used for light output equipment irradiation light.In addition, method of the present invention can also be used to shine previous because coke build-up causes the optical element of decay, with the optical element that shines these decay and make it return to its starting condition.

Therefore, the application of the invention can prolong the cleaning or the repair and replacement cycle that are used for the optical element in the above-mentioned vacuum zone, thereby helps to improve the operating rate of equipment and reduce maintenance cost.

As mentioned above, because the present invention can prevent or suppress the decay of optical system, and prolongs the maintenance cycle that it must be changed, therefore, help to improve the operating rate of equipment and reduce maintenance cost.

In addition, by will be according to the present invention optical system being attached to the equipment that uses light, can prolonging the life-span of this equipment and guarantee the output characteristic steady in a long-term of this equipment.

Claims (23)

1. one kind is used for by being positioned at output light or preventing along the opticpath of described output light, suppress, or improve the decay of the optical property of optical system, with the reliability of the optical property of improving optical system and the optical property recovery device in life-span, wherein said optical system is arranged in the nearly vacuum zone that organic composition can be decomposed, described decay is owing to deposit or accumulate in the irradiate light surface of described optical system, the light reflecting surface, the carbon on light emission surface (unified be called ' illumination surface ') produces, described surface is in the face of described vacuum zone, and described optical property restorer comprises:

Generation has nearly vacuum zone that active-energy the exists device with the oxidizing reaction that excites carbon, and described nearly vacuum zone is in the face of the described illumination surface of described optical system;

Produce the device of negative ion or group in described nearly vacuum zone;

Promotion is at the described negative ion of described nearly vacuum zone or the device of the oxidizing reaction between group and the described carbon; And

Wherein said optical property restorer is by the oxidizing reaction elimination or reduce the carbon that gathers that is deposited on described illumination surface.

2. one kind is used for by being positioned at output light or preventing along the opticpath of described output light, suppress, or improve the decay of the optical property of optical system, with the reliability of improvement optical system optical property and the optical property recovery device in life-span, wherein said optical system is arranged in the nearly vacuum zone that organic composition can be decomposed, described decay is owing to deposit or accumulate in the irradiate light surface of described optical system, the light reflecting surface, the carbon on light emission surface (unified be called ' illumination surface ') produces, described surface is in the face of described vacuum zone, and described optical property restorer comprises:

Produce the device of nearly vacuum zone with the oxidizing reaction that excites carbon, described nearly vacuum zone is in the face of the described illumination surface of described optical system;

Produce in described nearly vacuum zone and to contain for example device of the gas stream of aqueous vapor body or oxide gas of Sauerstoffatom gas;

Provide active-energy so that at the described device that produces the oxidation of coal reaction between Sauerstoffatom gas and the carbon that contains in described nearly vacuum zone; And

Wherein said optical property restorer is by the oxidizing reaction elimination or reduce the carbon that gathers that is deposited on described illumination surface.

3. one kind is used for by being positioned at output light or preventing along the opticpath of described output light, suppress, or improve the decay of the optical property of optical system, with the reliability of improvement optical system optical property and the optical property restoration methods in life-span, wherein said optical system is arranged in the nearly vacuum zone that organic composition can be decomposed, described decay is owing to deposit or accumulate in the irradiate light surface of described optical system, the light reflecting surface, the carbon on light emission surface (unified be called ' illumination surface ') produces, described surface is in the face of described vacuum zone, and described optical property restoration methods comprises step:

Generation has the nearly vacuum zone of active-energy existence to excite the oxidizing reaction of carbon, and described nearly vacuum zone is in the face of the described illumination surface of described optical system;

Produce negative ion or group in described nearly vacuum zone;

By making negative ion or group and sedimentary carbon react or reducing the carbon that gathers that accumulates in described illumination surface with elimination.

4. one kind is used for by being positioned at output light or preventing along the opticpath of described output light, suppress, or improve the decay of the optical property of optical system, with the reliability of improvement optical system optical property and the optical property restoration methods in life-span, wherein said optical system is arranged in the nearly vacuum zone that organic composition can be decomposed, described decay is owing to deposit or accumulate in the irradiate light surface of described optical system, the light reflecting surface, the carbon on light emission surface (unified be called ' illumination surface ') produces, described surface is in the face of described vacuum zone, and described optical property restoration methods comprises step:

Produce nearly vacuum zone to excite the oxidizing reaction of carbon under the condition that exists at the high reactivity energy excitation, wherein said nearly vacuum zone is in the face of the described illumination surface of described optical system; And

Provide active-energy when containing Sauerstoffatom gas for example the gas stream of water vapor or oxidizing gas enters into described nearly vacuum zone providing, thereby excite the oxidizing reaction of the carbon that gathers by the described active-energy that provides, to eliminate or to reduce the carbon that gathers that accumulates in described illumination surface.

5. optical property restoration methods according to claim 3 is characterized in that:

Described negative ion or group are the unstable chemical based that contains Sauerstoffatom, as OH base, OH ^-Ion, ozone, O ₂ ^-Ion, O ^-Base.

6. optical property restoration methods according to claim 4 is characterized in that:

The described Sauerstoffatom gas that contains is water vapor, oxygen, hydrogen peroxide, ozone or the mixed gas with described gas of rare gas element (comprising air).

7. according to claim 3 or 4 described optical property restoration methods, it is characterized in that:

Described optical system not only comprises the optical element of being made up of light transmission that is positioned at border, nearly vacuum zone or reflecting element, and comprise and be positioned at producing and the adjusting optical element of transmission and diffraction along the vacuum zone opticpath by diffraction, refraction, spectrum, and carry out the optical module that surface-treated optics object is formed by irradiation light, and described optical system also comprises position adjustments and maintaining body, container and the sealing member of described optical element or described optics object.

8. according to claim 3 or 4 described optical property restoration methods, it is characterized in that:

The light beam that forms described opticpath is to have 380nm wavelength or following common ultraviolet ray, or have 200nm wavelength or a following vacuum ultraviolet ray, exporting described ultraviolet ray or being positioned at along the described optical system of the opticpath of described output light is the optical material that comprises a kind of of fluorine cpd or combination, as magnesium fluoride, Calcium Fluoride (Fluorspan), barium fluoride, aluminum fluoride, sodium aluminum fluoride, Thiolite or other fluorine cpd, metal fluoride such as lanthanum fluoride, cadmium fluoride, neodymium fluoride, yttrium fluoride or as the high-purity mangesium oxide thing of artificial quartz glass or sapphire.

9. optical property restoration methods according to claim 4 is characterized in that:

Under the situation of growing on described optical system and the apparent surface, the described lower value that contains the pressure component of Sauerstoffatom gas that supplies to described nearly vacuum zone is set to the level above the speed of coke build-up at the carbon that decomposes from the organic composition of described nearly vacuum zone.

10. optical property restoration methods according to claim 4 is characterized in that:

When described vacuum ultraviolet ray shines described optical system or during from described irradiation optical system, under the situation that the described optical property of described optical system is recovered, the described higher limit that contains the pressure component of Sauerstoffatom gas that is used to supply to described nearly vacuum zone is preferably set to be lower than from it and realizes its view of function in described nearly vacuum zone, by described contain the vacuum ultraviolet absorption of Sauerstoffatom gas can not uncared-for level.

11. optical property restoration methods according to claim 10 is characterized in that:

The higher limit that is used to contain the pressure component of Sauerstoffatom gas is set at fills described nearly vacuum zone by reality and has the pressure component that necessarily contains Sauerstoffatom gas, measures on described opticpath vacuum ultraviolet quantity then to detect the level of its Reduction Level.

12., it is characterized in that according to claim 3 or 4 described optical property restoration methods:

The light beam that forms described opticpath is the light beam in the provision wavelengths of vacuum ultraviolet ray wavelength region.

13., it is characterized in that according to claim 3 or 4 described optical property restoration methods:

The light beam that forms described opticpath is the vacuum ultraviolet ray with high photon energy.

14. optical property restoration methods according to claim 4 is characterized in that:

When the described Sauerstoffatom gas that contains is oxygen, scope is that 0.02mtorr is to 20mtorr between the lower limit-upper limit of the pressure component of gas.

15. optical property restoration methods according to claim 4 is characterized in that:

When containing Sauerstoffatom gas and being water vapor, scope is set at 0.005mtorr to 20mtorr between the lower limit-upper limit of the pressure component of gas when described.

16. one kind comprises the optical system that is arranged on the fluorine cpd that are exposed to vacuum ultraviolet ray or plasma wire loop border, described vacuum ultraviolet ray or plasma line have the high photon energy of absorbing wavelength than the basic material of described optical system, wherein have the SiO of 2-20nm film thickness ₂Or the protective membrane of other metal oxide is formed on the irradiate light side (medial surface) of described optical system at least, to prevent the sur-face peeling of fluorine atom from described optical system.

17. one kind comprises the optical system that is arranged on the fluorine cpd that are exposed to vacuum ultraviolet ray or plasma wire loop border, described vacuum ultraviolet ray or plasma line have the high photon energy of absorbing wavelength than the basic material of described optical system, wherein have the SiO of 2-20nm film thickness ₂Or the protective membrane of other metal oxide is formed on the irradiate light side (medial surface) of described optical system at least, to prevent the surface oxidation of described optical system.

18. one kind comprises having the optical system that the isoionic fluorine cpd in the optical device that is placed in the inner area with plasma existence were faced and were exposed on the surface, wherein the 2nm-20nm protective membrane of high anti-plasma material is formed at the described surface that is exposed to described isoionic fluorine cpd.

19., it is characterized in that according to claim 16,17 or 18 described optical systems:

Described optical system is made up of the single crystal fluoride materials with the crystal axis (c axle) along the irradiate light direction, and the vertical surface of described protective membrane is coated with SiO ₂Or metal oxide.

20., it is characterized in that according to claim 16,17,18 or 19 described optical systems:

The protective membrane of described metal oxide is from Al ₂O ₃, MgO, TiO ₂, ZrO ₂In one of select.

21., it is characterized in that described protective membrane forms by ion beam sputtering method or plasma CVD according to claim 16,17,18,19 or 20 described optical systems.

22. a method of using optical device comprises step:

In advance will be from SiO ₂Or Al ₂O ₃, MgO, TiO ₂, ZrO ₂The protective membrane of the 2nm-20nm of middle a kind of metal oxide of selecting is applied on the optical system; wherein said film suppresses structural element because long-time irradiation of vacuum ultraviolet ray or the plasma-exposed sur-face peeling in basic material from basic material or the oxidation on the surface of basic material, and

Become in conjunction with described optical system and to have than the vacuum ultraviolet (VUV) line source of the higher photon energy of absorbing wavelength of described optical system basic material or the demand device in plasma light source.

23. the method for use optical device according to claim 22 is characterized in that:

Described light source provide the output of competent light with compensation because the initial decay of the described optical system that described protective membrane causes, and described optical system is arranged at the optical path of the described light source that is used to suppress the optical property decay after the described initial decay of described equipment.

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