CN205944718U - A dual wavelength reflection reducing coating and optical film thickness monitored control system for quasi -molecule laser - Google Patents
A dual wavelength reflection reducing coating and optical film thickness monitored control system for quasi -molecule laser Download PDFInfo
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- CN205944718U CN205944718U CN201620817613.9U CN201620817613U CN205944718U CN 205944718 U CN205944718 U CN 205944718U CN 201620817613 U CN201620817613 U CN 201620817613U CN 205944718 U CN205944718 U CN 205944718U
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Abstract
The utility model discloses a dual wavelength reflection reducing coating of quasi -molecule laser and be used for preparing the optical film thickness monitored control system of this reflection reducing coating to be applied to dark purple outer 193nm, the compatible quasi -molecule laser instrument of 248nm. The utility model discloses a dual wavelength reflection reducing coating of quasi -molecule laser includes the basement and set gradually the multilayer film that comprises in turn high -refractive -index film and low refractive index film in the basement, high -refractive -index film is for fluoridizing the lanthanum, and low refractive index film is the magnesium fluoride, the number of piles of multilayer film is 4~10 layers. An optical film thickness monitored control system, includes electron beam evaporation source, thermal resistance evaporation source, plates the basement, and electron beam evaporation source and thermal resistance evaporation source and quilt are plated is equipped with the baffle between the basement. The utility model discloses an absorb the scattering loss that is used for the dual wavelength reflection reducing coating of dark purple outer quasi -molecule laser, not only wavelength 193nm and 248nm have the remaining reflectivity of very low substrate surface, have moreover minimum .
Description
Technical field
This utility model is related to deep knowledge base instrument field and in particular to a kind of double for excimer laser
Wavelength anti-reflection film and optical film thickness monitoring system.
Background technology
Excimer laser is a kind of gas laser, and its working gas is mainly by highly stable lazy of chemical property under normality
Property gas atom argon (Ar), krypton (Kr), xenon (Xe) and the more active halogen atom fluorine (F) of chemical property, chlorine (Cl), bromine (Br),
Iodine (I) forms.Intert-gas atoms will not form molecule with other atoms in general, if but mix with halogen atom,
And with discharge type excitation, excited state molecule just can be produced.Then it is reduced to atom when excited state molecule transition returns to ground state again,
And release photon, photon launches laser after resonator cavity amplification.Because the molecule of this excited state is fleeting, its life-span
It is only few tens of nano-seconds, therefore claims its " quasi-molecule ", the laser of its transmitting claims its excimer laser.
Excimer laser has more than ten kinds so far, and most important wavelength is 157nm (F2), 193nm (ArF), 248nm
(KrF), 308nm (XeCl) and 351nm (XeF) etc., that wherein most widely used is 193nm and 248nm in deep ultraviolet band, institute
Meaning deep ultraviolet (DUV), often refers to wave band 190nm～280nm, and wavelength then claims VUV (VUV) less than 190nm, wavelength is more than
280nm then claims near ultraviolet (NUV).
Deep knowledge base has obvious feature：First, deep ultraviolet laser belongs to cold laser, makees with biological tissue
What the used time occurred is not heat effect, but photochemical reaction, so-called photochemical reaction, when referring to that tissue is subject to deep ultraviolet laser to act on,
Molecule associative key will be interrupted and Direct Resolution volatilization, and do not affect surrounding tissue, thus in laser medicine, particularly in ophthalmology
With there is in cardiovascular treatment important application.Secondly, deep ultraviolet laser output wave length, particularly wavelength 193nm is in
Deep ultraviolet and VUV edge, it is still can be in atmosphere with the minimal wave length compared with low-loss propagation, it is known that wavelength is got over
Short, resolution is higher, so being highly suitable in semiconductor lithography process etching accurate pattern, this is IC chip system
Make one of technology of middle most critical.Finally, the photon energy of deep ultraviolet laser is very high, in the photon energy of wavelength 193nm is
6.42eV, is 5eV in the photon energy of 248nm, and the power of Sing plus can reach hectowatt grade to MW class, the energy of Sing plus
Amount up to several joules to tens joules, so being highly suitable for Laser focus, material process and as laser weapon etc..
This utility model is directed to a kind of dual wavelength anti-reflection film for deep knowledge base, with adapt to 193nm,
The compatible deep knowledge base instrument of 248nm uses.But, on this wave band, not only the base material of high transparency is very
Limited, and the thin-film material being suitable for is also very limited, particularly high-index material.More notably, even if only few
Number several can material selection, due to the Electronic bandgap band gap of photon energy closely material, thus all can produce high absorption,
Very short plus wavelength, surface scattering is also very high, so optical loss is very big, this does not only result in absorbance and substantially reduces,
And lead to the destruction to thin film for the superlaser, Just because of this, the optical loss reducing thin film has become deep ultraviolet quasi-molecule to swash
The difficult point of optical thin film device design, here it is this utility model waits the key problem explored and solve.
Utility model content
The purpose of this utility model is to provide a kind of dual wavelength anti-reflection film for excimer laser and be used for preparing this
The optical film thickness monitoring system of anti-reflection film, to be applied to the excimer laser instrument of deep ultraviolet 193nm, 248nm compatibility.
Dual wavelength anti-reflection film for deep knowledge base of the present utility model, do not require nothing more than wavelength 193nm and
248nm has the residual reflectivity of low-down substrate surface, and requires anti-reflection film to have minimum absorption scattering loss, from
And, not only make anti-reflection film obtain highest absorbance, and improve the threshold value to film destruction for the excimer laser.For this this practicality
New design is as follows：
First, find extinction coefficient thin-film material as little as possible.It is necessary to be rolled over multiple for wavelength 193nm and 248nm
Penetrate rate to describe the optical characteristics of thin-film material, complex refractivity index N is the function of wavelength X, is represented by：N (λ)=n (λ)-ik
(λ), in formula, n (λ) is refractive index, and k (λ) claims extinction coefficient, and it can characterize the size absorbing scattering loss.To wavelength 193nm and
248nm is it is necessary first to be determined by experiment the various thin-film materials that may be applied to this wave band and its complex refractivity index.Secondly,
By the complex refractivity index obtaining, high refractive index film and low-refraction membrane material are selected according to principle chosen below：1). high and low refraction
The refractivity of rate bi-material is larger；2). the refractive index of low-index material is little as much as possible；3). more importantly high and low
The extinction coefficient of refractive index bi-material will be sufficiently small；4). the machinery of material, chemical property disclosure satisfy that actually used wanting
Ask.
Because thin-film material applies simultaneously to wavelength 193nm and 248nm, and the loss of wavelength 193nm is always than 248nm
Greatly, so the photon energy of wavelength available 193nm and Electronic bandgap band gap the foundation of preliminary screening spillage of material might as well be used as.
Make simple process：Because when photon energy h ν is equal to Electronic bandgap band gap EgWhen, just for the short-wave absorption belt edge of material,
Then the wavelength X at material short-wave absorption edge can be obtained wherebyc, i.e. due to Eg=h ν=hc/ λc, in formula, h, ν, c are respectively
Planck's constant, light frequency and the light velocity, the then wavelength X at short-wave absorption edgec=hc/Eg, to long wave further away from λc, light loss
Less.If calculate lacking data, also can more simply utilize the relation of Refractive Index of Material n：n4/λc≈ constant, to this practicality
New material, the constant of high-index material is about 42, and the constant of low-index material is about 35.Accordingly, this reality
There is LaF with the new high-index material obtaining being likely to be suited for wavelength 193nm3And Al2O3, obtain being likely to be suited for wavelength
The low-index material of 193nm mainly has MgF2And SiO2.Then these four materials are tested and tested inverting, obtained
The complex refractivity index of wavelength 193nm and 248nm is as shown in table 1.
Table 1
As known from Table 1, although Al in two kinds of high-index materials2O3The refractive index of film is higher, thus can reach high and low
The refractivity of refractive index bi-material is larger, but regrettably Al2O3Extinction coefficient k too big, it is advantageous to LaF3；Two kinds
In low-index material, MgF2Refractive index less, Bees Wax k is also less, preferably MgF2.Thus determine LaF3With
MgF2Respectively as the preferred high-index material of this utility model and low-index material.
Second, according to the material determining and complex refractivity index, the anti-reflection film of design high-transmission rate.According to preservation of energy：T+R+L
=1, in formula, T represents the absorbance of anti-reflection film, and R represents the residual reflectivity of anti-reflection film, and L is the absorption scattering loss of anti-reflection film.
In longer wavelengths of visible region, usually it is ignored because L is sufficiently small, as long as so final design can make reflectance enough
Little, absorbance just can be close to 1；But to wavelength 193nm and 248nm, absorb scattering loss larger, so substrate table should be realized
The low residual reflectivity in face, realizes the low-loss of thin film again simultaneously, and absorbance just can be made to reach greatly.In other words, in long wave
The design in low-loss area is only substrate surface " antireflective ", therefore often claims antireflective coating；And in deep ultraviolet 193nm and 248nm, if
Meter emphasis includes " antireflective " of substrate surface and " low-loss " of film layer, to obtain high-transmission rate, therefore claims anti-reflection film, and not
Preferably claim antireflective coating again.According to this conception, during design anti-reflection film, residual reflectivity and absorption scattering loss are both included as
The composition part of evaluation function, and be sufficient to unlike long wave low-loss area only evaluates residual reflectivity.
According to above-mentioned conception, from high-index material LaF3With low-index material MgF2, increasing in four kinds of quartz substrate
The design result of permeable membrane is listed in table 2.By design result it can be found that：1). the high refractive index film of anti-reflection film and low refractive index film
Total film layer number is even number, and wherein, odd-level is the LaF of high index of refraction3, even level is the MgF of low-refraction2；2). with anti-reflection
Film total film layer number increases, and total thicknesses of layers accordingly thickens, residual reflectivity tend to reduce (can with two wavelength and evaluating),
So only in terms of antireflecting effect, increasing total film layer number and be highly profitable, but, because total film layer number increases, total film layer
Thickness tends to thicken, and the loss of thin film can steeply rise, and then final absorbance declines on the contrary, here it is of the present utility model
Anti-reflection film and the essential distinction of conventional antireflective coating, in other words, in wavelength 193nm and 248nm it is impossible to only consider residual reflectivity
Rate is it is often more important that the thin film loss of minimum and the absorbance of maximum will be considered, this not only can increase transmission potential, prior
It is the threshold for resisting laser damage improving anti-reflection film；3). in wavelength 193nm and 248nm, because thin film loss is far longer than remnants instead
Penetrate rate, so, on the premise of ensureing sufficiently small residual reflectivity, it is to close with the loss of minimum thin film or maximum transmission rate for criterion
Reason, by this criterion, preferred version undoubtedly should select 4 minimum Rotating fields of film layer gross thickness, rather than residual reflectivity is less
6,8,10 Rotating fields.So, result can more preferably for the anti-reflection film of 2 Rotating fields？Answer is negative, because 2 Rotating fields
Although thin film loss is really less than 4 layers, due to design parameter very little, it has been not enough to obtain the anti-reflection film of dual wavelength, namely right
Wavelength 193nm and 248nm, 2 Rotating fields no solve.
Table 2
3rd, how to manufacture the dual wavelength anti-reflection film meeting design requirement.In deep ultraviolet, the problem of most critical is thickness prison
Control.Prior art conventional two kinds of methods when solving deep ultraviolet film thickness monitoring：One is to control film quality using quartz crystal
Obtain thickness, but the control error of this method is larger, very unsuitable；Two is independently to set up a set of photoelectricity film-thickness monitoring, but
Because deep ultraviolet light source-optical system-receptor is completely different with visible region, so not only expensess are very big, and
Time-consuming very long.The utility model proposes solve this problem with plate washer method, if taking the centre wavelength of 193nm and 248nm to be
220nm, then select visible ray to control wavelength 440nm, and plate washer used is precisely that gear removes the vapor molecule stream of half, plate washer design and
Make not only simple but also accurate.So there is no need to change coater original blooming control system, as long as by plated film base
Beneath face increases by one piece of plate washer it is possible to realize the thickness control of DUV area anti-reflection film with the photo-electric control of existing visible region
System.
For achieving the above object, the concrete technical scheme that this utility model is taken is：
A kind of dual wavelength anti-reflection film for excimer laser, including substrate and set gradually on the substrate by height
Refractive index film and low refractive index film replace the multilayer film constituting；
Described high refractive index film is lanthanum fluoride (LaF3), described low refractive index film is Afluon (Asta) (MgF2)；
The number of plies of described multilayer film is 4～10 layers.
In this utility model, the dual wavelength anti-reflection film for excimer laser of said structure, have less thin film loss concurrently
Higher absorbance, is highly suitable for the compatible excimer laser instrument of deep ultraviolet 193nm, 248nm.
Following as optimal technical scheme of the present utility model：
Described substrate is fused silica or calcium fluoride (CaF2).
Described double wave a length of argon fluoride lasers wavelength 193nm and KrF laser wavelength 248nm.
Described high refractive index film LaF3It is 1.72-i7 × 10 in the complex refractivity index of wavelength 193nm- 4, in wavelength 248nm
Complex refractivity index be 1.68-i3 × 10- 4；
Described low refractive index film MgF2It is 1.44-i4.7 × 10 in the complex refractivity index of wavelength 193nm- 4, in wavelength
The complex refractivity index of 248nm is 1.41-i1 × 10- 4；
Total film layer number (i.e. total film layer number of high refractive index film and low refractive index film) of described multilayer film is even number, its
In, by substrate outwards, odd-level is lanthanum fluoride (LaF3), even level is Afluon (Asta) (MgF2).
Total film layer number of described multilayer film is 10 layers, and film layer gross thickness is 255.2nm, and by substrate outwards, odd-level is
Lanthanum fluoride (LaF3), even level is Afluon (Asta) (MgF2), the 1st to 10 layer of thickness is followed successively by：15.34,23.17,10.06,
34.50,30.93,21.16,10.46,40.17,31.61,37.80, unit is nm.
Total film layer number of described multilayer film is 8 layers, and film layer gross thickness is 194.6nm, and by substrate outwards, odd-level is fluorine
Change lanthanum (LaF3), even level is Afluon (Asta) (MgF2), the 1st to 8 layer of thickness is followed successively by：5.03,8.66,40.64,22.67,
3.92,44.04,31.94,37.70, unit is nm.
Total film layer number of described multilayer film is 6 layers, and film layer gross thickness is 181.4nm, and by substrate outwards, odd-level is fluorine
Change lanthanum (LaF3), even level is Afluon (Asta) (MgF2), the 1st to 6 layer of thickness is followed successively by：44.51,24.15,3.41,40.89,
31.16,37.23, unit is nm.
Total film layer number of described multilayer film is 4 layers, and film layer gross thickness is 169.2nm, and by substrate outwards, odd-level is fluorine
Change lanthanum (LaF3), even level is Afluon (Asta) (MgF2), the 1st to 4 layer of thickness is followed successively by：16.47,83.38,30.31,38.99,
Unit is nm.
The preferred version of excimer laser dual wavelength anti-reflection film is 4 film structure, and the gross thickness of its multilayer film is
169.2nm；It is followed successively by from the thickness of the outside each film layer of substrate：16.47,83.38,30.31,38.99, unit is nm.This is preferred
Technical scheme can obtain：To wavelength 193nm (ArF), one side absorbance is 99.40%；To wavelength 248nm (KrF), one side transmission
Rate is 99.82%.
The manufacturing technology scheme of this excimer laser dual wavelength anti-reflection film preferably uses plate washer method, to use original visible ray
The film thickness monitoring of the photoelectricity extreme value control realization DUV area anti-reflection film in area.If taking the centre wavelength of 193nm and 248nm to be
220nm, then select visible ray to control wavelength 440nm to control film thickness, and now, gear removes half vapor molecule stream to plate washer just,
Plate washer is made to design and produce not only simple but also accurate.Further, replace 2 stepper plate using 8 stepper plate, thin films growing microstructure can be made to obtain
To improvement.
A kind of optical film thickness monitoring system, including light source, condenser lenses, film thickness monitoring piece, optical filter, receptor, electronics
Beam evaporation source, thermal resistance evaporation source, work piece holder disk and plated substrate, described electron beam evaporation source and thermal resistance evaporation source and quilt
It is provided with baffle plate between plating substrate, divided with a part of thin-film material blocking electron beam evaporation source and when thermal resistance evaporation source evaporates respectively
Son, obtains the deep ultraviolet thickness of requirement in substrate.
Described baffle plate is circle, and centre is provided with plate washer central circular hole.
Described baffle plate adopts bisection method to split, and clips half in the baffle plate being provided with plate washer central circular hole.
Described baffle plate adopts octave device to split, and is divided into the eight of equal portions in the circumference of the baffle plate being provided with plate washer central circular hole
Block, clip interval in eight pieces four pieces.
Compared with prior art, the beneficial effects of the utility model are：
1). the excimer laser anti-reflection film of prior art is only applicable to the situation of Single wavelength, such as the quasi-molecule of wavelength 193nm
Laser anti-reflection film, excimer laser anti-reflection film of wavelength 248nm etc. are it is clear that these anti-reflection films are not applied for up-to-date proposition
In the excimer laser instrument of 193nm and 248nm dual wavelength dual-purpose.But the excimer laser manufacturing and designing dual wavelength dual-purpose increases
Permeable membrane, not only difficulty greatly increase, and, more notably, can be seen that the excimer laser of dual wavelength dual-purpose from Fig. 2 and Fig. 4
The thin film loss of anti-reflection film can be bigger many than Single wavelength anti-reflection film, and this is a very big challenge to the damage from laser of thin film.Study carefully
Its reason, be primarily due to Single wavelength anti-reflection film gross thickness can ratio relatively thin, such as to wavelength 193nm, the gross thickness of anti-reflection film
It is only 110nm, gross thickness 169.2nm the thinnest decreases about 1/3 than in dual wavelength anti-reflection film of the present utility model.Obviously, if
Count and prepare low-loss dual wavelength anti-reflection film of crucial importance to deep knowledge base application.
2). the antireflecting coating design of prior art generally only evaluates residual reflectivity, but in deep ultraviolet of the present utility model
In excimer laser thin film, only evaluate residual reflectivity and can not possibly obtain minimum optical loss, for this reason, this utility model carries
Go out on the premise of ensureing sufficiently small residual reflectivity, using the loss of minimum thin film or maximum transmission rate sentencing as design evaluatio
According to.With this criterion, the transmission potential of deep knowledge base instrument not only can be increased, reduce veiling glare, improve contrast
With resolution it is often more important that being lost due to minimum thin film can be obtained in dual wavelength anti-reflection film, thus can improve double
The threshold for resisting laser damage of wavelength anti-reflection film.
3). the preparation of the dark purple outer film of prior art frequently with quartz crystal film-thickness monitoring, but due to this kind of instrument
Control principle be that film thickness is obtained based on film quality, so closely related with the density of film layer, in other words, thin
Film thickness is closely related with preparation parameter, thus easily causes larger film thickness error.For this reason, to high accuracy film thickness monitoring, must
Optical thickness must be obtained using the photo-electric control based on optical interference.Regrettably, in deep ultraviolet band, Light Electronic Control System
Entirely different near ultraviolet and visible region, so developing new DUV electrolemma thickness control system is not only cost but also an expense
When thing.For this utility model proposes solve this difficult problem with plate washer method, if taking the centre wavelength of 193nm and 248nm to be
220nm, then select visible ray to control wavelength 440nm, plate washer used is precisely the vapor molecule stream that gear goes half, and this makes plate washer
Design and making were not only simple but also accurate.So on the premise of not changing coater original visible ray film thickness monitoring system, as long as
Increase by one piece of plate washer so that it may realize the film of DUV area anti-reflection film with the photo-electric control of visible region below by plated film substrate
Thick control.
Brief description
Fig. 1 is bent for test refractive index (a) of deep knowledge base anti-reflection film thin-film material and extinction coefficient (b)
Line, wherein, in Fig. 1, (a) is the test refractive index curve for deep knowledge base anti-reflection film thin-film material, in Fig. 1 (b)
It is the extinction coefficient curve for deep knowledge base anti-reflection film thin-film material；
Fig. 2 is reflectance (solid line) and the loss (dotted line) of the deep knowledge base Single wavelength anti-reflection film of prior art
Curve, wherein, in Fig. 2, (a) is the reflectance of the deep knowledge base Single wavelength anti-reflection film of prior art under wavelength 193nm
(solid line) and loss (dotted line) curve, in Fig. 2, (b) is the deep knowledge base Single wavelength of prior art under wavelength 248nm
The reflectance (solid line) of anti-reflection film and loss (dotted line) curve；
Fig. 3 is the thickness of deep knowledge base dual wavelength anti-reflection film of the present utility model and the corresponding relation of refractive index
Figure, wherein, in Fig. 3, (a) is the film of the deep knowledge base dual wavelength anti-reflection film that this utility model total film layer number is 10 layers
The thick corresponding relation figure with refractive index；In Fig. 3, (b) is that the deep knowledge base that this utility model total film layer number is 8 layers is double
The corresponding relation figure of the thickness of wavelength anti-reflection film and refractive index；In Fig. 3 (c) be this utility model total film layer number be 6 layers dark purple
The thickness of outer excimer laser dual wavelength anti-reflection film and the corresponding relation figure of refractive index；In Fig. 3, (d) is the total film layer of this utility model
Number is 4 layers of the thickness of deep knowledge base dual wavelength anti-reflection film and the corresponding relation figure of refractive index；
Fig. 4 is reflectance (solid line) and the loss (void of deep knowledge base dual wavelength anti-reflection film of the present utility model
Line) curve comparison diagram；Wherein, in Fig. 4, (a) is the deep knowledge base dual wavelength that this utility model total film layer number is 10 layers
The reflectance (solid line) of anti-reflection film and loss (dotted line) curve comparison diagram；In Fig. 4, (b) is that this utility model total film layer number is 8 layers
The reflectance (solid line) of deep knowledge base dual wavelength anti-reflection film and loss (dotted line) curve comparison diagram；In Fig. 4, (c) is
This utility model total film layer number is reflectance (solid line) and the loss (void of 6 layers of deep knowledge base dual wavelength anti-reflection film
Line) curve comparison diagram；In Fig. 4, (d) is the deep knowledge base dual wavelength anti-reflection film that this utility model total film layer number is 4 layers
Reflectance (solid line) and loss (dotted line) curve comparison diagram；
The transmittance graph comparison diagram of Fig. 5 deep knowledge base of the present utility model dual wavelength anti-reflection film；Wherein, scheme
The transmittance graph ratio of the deep knowledge base dual wavelength anti-reflection film that (a) is 10 layers for this utility model total film layer number in 5
Relatively scheme；The absorbance of the deep knowledge base dual wavelength anti-reflection film that (b) is 8 layers for this utility model total film layer number in Fig. 5
Curve comparison diagram；The deep knowledge base dual wavelength anti-reflection film that in Fig. 5, (c) is 6 layers for this utility model total film layer number
Transmittance graph comparison diagram；The deep knowledge base dual wavelength that in Fig. 5, (d) is 4 layers for this utility model total film layer number increases
The transmittance graph comparison diagram of permeable membrane；
Fig. 6 be baffle plate used by this utility model with by the relative position of plated film substrate and blooming control system
Structural representation；
Fig. 7 is the schematic shapes of baffle plate used by this utility model, and wherein, in Fig. 7, (a) is the gear using bisection method segmentation
The structural representation of plate, in Fig. 7, (b) is the structural representation of the baffle plate using octave device segmentation.
Specific embodiment
This utility model to be implemented it may first have to find be expected for deep ultraviolet band high refractive index, thin film materials and
The thin-film material of low-refraction.Because the loss of wavelength 193nm is always big than 248nm, it is possible to being applied to wavelength 193nm's
Material, must also can be suitably used for wavelength 248nm.As such, it is possible to the photon energy by means of wavelength 193nm and Electronic bandgap band gap
As the foundation of preliminary screening spillage of material, through screening, show that high-index material has LaF3And Al2O3, and low-refraction material
Material is relatively more, such as MgF2、AlF3、CaF2And SiO2Deng, but comprehensive according to properties such as machinery, chemistry and optics, select MgF2With
SiO2Relatively rationally.Then monolayer and multilayer film evaporation reality are carried out to this two kinds of high-index materials and two kinds of low-index materials
Test and optical constant test inverting, Fig. 1 represents that these four thin-film materials of deep ultraviolet band are tested the refractive index (a) obtaining and disappeared
Backscatter extinction logarithmic ratio (b) curve, wherein, two kinds of high refractive index films are as follows in the optical constant of wavelength 193nm：To LaF3, refractive index is
1.72, extinction coefficient are 7 × 10- 4；To Al2O3, refractive index is 1.83, and extinction coefficient are 6 × 10- 3.And two kinds of low refractive index films
In the optical constant of wavelength 193nm it is：To MgF2, refractive index is 1.44, and extinction coefficient are 4.7 × 10- 4；To SiO2, refractive index
For 1.57, extinction coefficient are 5.6 × 10- 4.Similarly, two kinds of high refractive index films are as follows in the optical constant of wavelength 248nm：Right
LaF3, refractive index is 1.68, and extinction coefficient are 3 × 10- 4；To Al2O3, refractive index is 1.78, and extinction coefficient are 1 × 10- 3.And two
Planting low refractive index film in the optical constant of wavelength 248nm is：To MgF2, refractive index is 1.41, and extinction coefficient are 1 × 10- 4；Right
SiO2, refractive index is 1.53, and extinction coefficient are 1.1 × 10- 4.To high refractive index film, high refractive index means to obtain little
Residual reflectivity.From the optical constant of test it is recognized that while Al2O3Refractive index be more than LaF3, but due to obtaining low extinction coefficient
(low-loss) ratio obtains high index of refraction much more significant, therefore undoubtedly should the much smaller LaF of preferred extinction coefficient3.To low-refraction
Film, lower refractive index means less residual reflectivity it is clear that in MgF2And SiO2Extinction coefficient much the same in the case of,
Answer the MgF that preferred index is lower2.In the following embodiments, this utility model all takes high-index material LaF3With low refraction
Rate material MgF2Implemented.
Fig. 2 is reflectance (solid line) and the loss (dotted line) of the deep knowledge base Single wavelength anti-reflection film of prior art
Curve, wherein, (a) is wavelength 193nm, and (b) is wavelength 248nm.Although Single wavelength anti-reflection film 2 Rotating fields of prior art also have
Solution, but can not be accepted because its residual reflectivity is still very high, and 3-tier architecture can obtain the result of satisfaction, this and total film
The number of plies is that the dual wavelength anti-reflection film of even number has essential difference.To wavelength 193nm, total thicknesses of layers of 3-tier architecture is
110nm, residual reflectivity is zero, is lost as 0.379%；And to wavelength 248nm, total thicknesses of layers of 3-tier architecture is 145nm, residual
Coreflection is zero, is lost as 0.129%.Regrettably, the Single wavelength anti-reflection film of prior art can not meet of the present utility model
The use condition of dual wavelength anti-reflection film.
Similar to Fig. 2, Fig. 4 is the reflectance (solid line) of deep knowledge base dual wavelength anti-reflection film of the present utility model
With loss (dotted line) curve ratio relatively, wherein, (a) film layer number is 10 layers, and (b) is 8 layers, and (c) is 6 layers, and (d) is 4 layers.It should be mentioned that
, illustrate only 4 solutions in Fig. 4 it is clear that also having more solutions, but because the inevitable film layer number of these solutions is more, gross thickness
Thicker, so its result will not better than this 4 solutions illustrating, thus also just there is no need to give again.
Embodiment 1 of the present utility model：Film layer number is 10 layers, and wherein odd-level is high-index material LaF3, even level
For low-index material MgF2.Film layer gross thickness is 255.2nm, from the beginning of substrate fused silica, each layer high and low refractive index alternate films
The thickness of layer is followed successively by：15.34,23.17,10.06,34.50,30.93,21.16,10.46,40.17,31.61,37.80, single
Position is nm, and Fig. 3 (a) represents the corresponding relation of its thicknesses of layers and refractive index.The residual reflectivity of the present embodiment 1 and loss are shown in
The residual reflectivity of Fig. 4 (a), and its absorbance is shown in Fig. 5 (a), its medium wavelength 193nm is 0.001%, is lost as 0.947%,
Then one side absorbance reaches 99.052%, and the residual reflectivity of wavelength 248nm is 0.000%, is lost as 0.266%, in
It is that one side absorbance can reach 99.734%.Obviously, the reason cause the present embodiment 1 transmission loss is exactly thin film loss, and table
Face residual reflectivity is negligible.
Embodiment 2 of the present utility model：Film layer number is 8 layers, and wherein odd-level is high-index material LaF3, even level is
Low-index material MgF2.Film layer gross thickness is 194.6nm, from the beginning of substrate fused silica, each layer high and low refractive index alternate membrane
Thickness be followed successively by：5.03,8.66,40.64,22.67,3.92,44.04,31.94,37.70, unit is nm, and Fig. 3 (b) represents
Its thicknesses of layers and the corresponding relation of refractive index.The residual reflectivity of the present embodiment 2 and loss are shown in Fig. 4 (b), and its absorbance
It is shown in Fig. 5 (b), the residual reflectivity of its medium wavelength 193nm is 0.006%, be lost as 0.749%, then one side absorbance can
Reach 99.245%, and the residual reflectivity of wavelength 248nm is 0.011%, be lost as 0.206%, then one side absorbance can
Reach 99.783%.Obviously, the reason cause the present embodiment 2 transmission loss is mainly thin film loss.
Embodiment 3 of the present utility model：Film layer number is 6 layers, and wherein odd-level is high-index material LaF3, even level is
Low-index material MgF2.Film layer gross thickness is 181.4nm, from the beginning of substrate fused silica, each layer high and low refractive index alternate membrane
Thickness be followed successively by：44.51,24.15,3.41,40.89,31.16,37.23, unit is nm, and Fig. 3 (c) represents that its film layer is thick
Degree and the corresponding relation of refractive index.The residual reflectivity of the present embodiment 3 and loss are shown in Fig. 4 (c), and its absorbance is shown in Fig. 5
C (), the residual reflectivity of its medium wavelength 193nm is 0.008%, is lost as 0.678%, and then one side absorbance can reach
99.314%, and the residual reflectivity of wavelength 248nm is 0.010%, is lost as 0.196%, then one side absorbance can reach
99.794%.
Embodiment 4 of the present utility model：Film layer number is 4 layers, and wherein odd-level is high-index material LaF3, even level is
Low-index material MgF2.Film layer gross thickness is 169.2nm, from the beginning of substrate fused silica, each layer high and low refractive index alternate membrane
Thickness be followed successively by：16.47,83.38,30.31,38.99, unit is nm, and Fig. 3 (d) represents its thicknesses of layers and refractive index
Corresponding relation.The residual reflectivity of the present embodiment 4 and loss are shown in Fig. 4 (d), and its absorbance is shown in Fig. 5 (d), its medium wavelength
The residual reflectivity of 193nm is 0.002%, is lost as 0.601%, and then one side absorbance can reach 99.397%, and wavelength
The residual reflectivity of 248nm is 0.028%, is lost as 0.156%, and then one side absorbance can reach 99.816%.Obviously, originally
Embodiment 4 has the thin film loss of minimum and maximum absorbance.
Can be seen that from above four embodiments：1). gradually decrease with dual wavelength anti-reflection film total film layer number, total film layer is thick
Degree is accordingly thinning, residual reflectivity tend to be gradually increased (with two wavelength of 193nm and 248nm and evaluating)；2). total film layer
Number reduces, and total thicknesses of layers is thinning, and the loss of thin film strongly reduces, and absorbance increases.In other words, in deep ultraviolet wavelength, no
Can only consider to obtain minimum residual reflectivity it is often more important that the thin film loss of minimum will be considered to obtain the transmission of maximum
Rate, this not only can increase the transmission potential of thin film it is often more important that the anti-excimer laser damage threshold of thin film can be improved；3).
In deep ultraviolet band, particularly wavelength 193nm, because thin film loss is far longer than residual reflectivity, it is advantageous to scheme is undoubtedly
4 minimum Rotating fields of film layer gross thickness should be selected, rather than less 6,8,10 Rotating fields of residual reflectivity；4). film layer number is more than 10
During layer, atomic to the contribution reducing residual reflectivity, but considerably increase film layer loss, therefore film layer number can not be more than 10 layers；
5). when film layer number is less than 4 layers, the dual wavelength anti-reflection film of 193nm and 248nm is no solved.
Manufacture above-mentioned deep ultraviolet dual wavelength anti-reflection film, the problem of most critical is how to implement film thickness monitoring, that is afraid of to the simplest
4 single film structure are also still such.As it was previously stated, the quartz crystal that prior art solves deep ultraviolet film thickness monitoring controls, film
Thick control error is larger；And independently set up a set of DUV electrolemma apparatus for controlling thickness, not only cost but also time-consuming.For this reason, this practicality is new
Type proposition solves this problem with plate washer method, so there is no need to change coater original blooming control system, as long as
Increase the film thickness monitoring that one piece of plate washer can implement deep ultraviolet band below by plated film substrate.Fig. 6 is used by this utility model
Baffle plate with by the configuration schematic diagram of the relative position of plated film substrate and original blooming control system.As shown in Fig. 6,
Optical film thickness monitoring system is mainly made up of light source 6, condenser lenses 7, film thickness monitoring piece 8, optical filter 9 and receptor 10 etc..Often
The thickness of layer film is all measured with monitoring piece 8.In Fig. 6,1 is electron beam evaporation source, and 2 is thermal resistance evaporation source, evaporates successively respectively
High-index material LaF3With low-index material MgF2.Plated substrate 3 is placed on work piece holder disk 4 (actual in work piece holder disk
4 peripheries pile plated substrate 3, not only the plated substrate 3 only shown in figure), because during plated film, work piece holder disk 4 quickly turns
Dynamic, so all plated suprabasil characteristics are the same.Thickness baffle plate 5 just nestles up the lower section being placed in plated substrate 3, to hide
A part of thin-film material molecule when gear electron beam evaporation source 1 and thermal resistance evaporation source 2 evaporate respectively, obtains requirement in substrate
Deep ultraviolet thickness.
Fig. 7 shows shape and the manufacture method of baffle plate used by this utility model, and wherein, (a) is bisection method, and (b) is eight
Point-score.If taking the centre wavelength of 193nm and 248nm to be 220nm, visible ray is selected to control wavelength 440nm, plate washer needs to keep off just
Remove half thin-film material vapor molecule stream, such plate washer design and making very simply again can be very accurate.As shown in Fig. 7 (a),
The diameter of plate washer 5 is equal with work piece holder disk 4, to be installed to below work piece holder disk 4；The diameter of plate washer central circular hole 11 with
Film thickness monitoring piece 8 is equal, so that the control light of wavelength 440nm all passes through；Keep off half vapor molecule stream, only need to be plate washer
To dividing, clip half, retain another twilight-zone.If the thickness 440nm so on film thickness monitoring piece 8, then in quilt
Thickness in plating substrate 3 is just 220nm.The shortcoming of this bisection method is that thin film growth affects thin film because interval time is longer
Growth structure, for avoiding or mitigating this impact, proposes to adopt eight stepper plate, based on eight stepper plate utilize 45 ° of fan shape baffles,
As shown in the shadow region of Fig. 7 (b), this makes to manufacture and design and remains to keep simple and accurate feature, but alleviates to stepper plate
Shortcoming.
Claims (9)
1. a kind of dual wavelength anti-reflection film for excimer laser is it is characterised in that including substrate and being successively set on described
The multilayer film being alternately made up of high refractive index film and low refractive index film in substrate；
Described high refractive index film is lanthanum fluoride, and described low refractive index film is Afluon (Asta)；
The number of plies of described multilayer film is 4～10 layers.
2. the dual wavelength anti-reflection film for excimer laser according to claim 1 is it is characterised in that described substrate is
Fused silica or calcium fluoride.
3. the dual wavelength anti-reflection film for excimer laser according to claim 1 is it is characterised in that described multilayer film
Total film layer number be even number, wherein, by substrate outwards, odd-level is lanthanum fluoride, and even level is Afluon (Asta).
4. the dual wavelength anti-reflection film for excimer laser according to claim 3 is it is characterised in that described multilayer film
Total film layer number be 10 layers, film layer gross thickness is 255.2nm, and by substrate outwards, odd-level is lanthanum fluoride, and even level is fluorination
Magnesium, the 1st to 10 layer of thickness is followed successively by：15.34,23.17,10.06,34.50,30.93,21.16,10.46,40.17,
31.61,37.80, unit is nm.
5. the dual wavelength anti-reflection film for excimer laser according to claim 3 is it is characterised in that described multilayer film
Total film layer number be 8 layers, film layer gross thickness is 194.6nm, and by substrate outwards, odd-level is lanthanum fluoride, and even level is Afluon (Asta),
1st to 8 layer of thickness is followed successively by：5.03,8.66,40.64,22.67,3.92,44.04,31.94,37.70, unit is nm.
6. the dual wavelength anti-reflection film for excimer laser according to claim 3 is it is characterised in that described multilayer film
Total film layer number be 6 layers, film layer gross thickness is 181.4nm, and by substrate outwards, odd-level is lanthanum fluoride, and even level is Afluon (Asta),
1st to 6 layer of thickness is followed successively by：44.51,24.15,3.41,40.89,31.16,37.23, unit is nm.
7. the dual wavelength anti-reflection film for excimer laser according to claim 3 is it is characterised in that described multilayer film
Total film layer number be 4 layers, film layer gross thickness is 169.2nm, and by substrate outwards, odd-level is lanthanum fluoride, and even level is Afluon (Asta),
1st to 4 layer of thickness is followed successively by：16.47,83.38,30.31,38.99, unit is nm.
8. a kind of optical film thickness monitoring system, including electron beam evaporation source, thermal resistance evaporation source, plated substrate it is characterised in that institute
It is provided with baffle plate between the electron beam evaporation source stated and thermal resistance evaporation source and plated substrate.
9. optical film thickness monitoring system according to claim 8 is it is characterised in that described baffle plate is circle, this baffle plate
Centre is provided with plate washer central circular hole, and baffle plate adopts bisection method segmentation or octave device segmentation.
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| CN201620817613.9U CN205944718U (en) | 2016-07-29 | 2016-07-29 | A dual wavelength reflection reducing coating and optical film thickness monitored control system for quasi -molecule laser |
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|---|---|---|---|
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106067652A (en) * | 2016-07-29 | 2016-11-02 | 杭州科汀光学技术有限公司 | A kind of dual wavelength anti-reflection film for excimer laser and optical film thickness monitoring system |
| CN107893216A (en) * | 2017-09-30 | 2018-04-10 | 同济大学 | A kind of method corrected quartzy monitoring method and prepare broadband anti-reflection film deposition errors |
-
2016
- 2016-07-29 CN CN201620817613.9U patent/CN205944718U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106067652A (en) * | 2016-07-29 | 2016-11-02 | 杭州科汀光学技术有限公司 | A kind of dual wavelength anti-reflection film for excimer laser and optical film thickness monitoring system |
| CN106067652B (en) * | 2016-07-29 | 2022-03-08 | 杭州科汀光学技术有限公司 | Dual-wavelength antireflection film for excimer laser and optical film thickness monitoring system |
| CN107893216A (en) * | 2017-09-30 | 2018-04-10 | 同济大学 | A kind of method corrected quartzy monitoring method and prepare broadband anti-reflection film deposition errors |
| CN107893216B (en) * | 2017-09-30 | 2020-04-28 | 同济大学 | Method for correcting deposition error of broadband antireflection film prepared by quartz monitoring method |
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