Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
  • G03F7/7095—Materials, e.g. materials for housing, stage or other support having particular properties, e.g. weight, strength, conductivity, thermal expansion coefficient
  • G03F7/70958—Optical materials or coatings, e.g. with particular transmittance, reflectance or anti-reflection properties
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
  • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
  • G02B1/11—Anti-reflection coatings
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70058—Mask illumination systems
  • G03F7/70191—Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70058—Mask illumination systems
  • G03F7/70075—Homogenization of illumination intensity in the mask plane by using an integrator, e.g. fly's eye lens, facet mirror or glass rod, by using a diffusing optical element or by beam deflection
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70216—Mask projection systems
  • G03F7/70233—Optical aspects of catoptric systems, i.e. comprising only reflective elements, e.g. extreme ultraviolet [EUV] projection systems
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70216—Mask projection systems
  • G03F7/70308—Optical correction elements, filters or phase plates for manipulating imaging light, e.g. intensity, wavelength, polarisation, phase or image shift

Definitions

• This invention relates to microlithographic projection exposure apparatuses used in the manufacture of highly-integrated electrical circuits and other microstructured components. More particularly, the invention relates to coatings of optical elements to increase or decrease the reflectivity.
• Integrated electrical circuits and other microstructured devices are typically fabricated by applying a plurality of patterned layers to a suitable substrate, which may be a silicon wafer, for example.
• a photoresist which is sensitive to light of a specific wavelength range, for example light in the deep ultraviolet spectral range (DUV, deep ultraviolet).
• DUV deep ultraviolet
• the thus coated wafer is exposed in a projection exposure apparatus.
• a mask containing a pattern of structures from a Lighting system illuminated and imaged using a projection lens on the photoresist. Since the magnification is generally less than one, such projection lenses are often referred to as reduction lenses.
• the wafer After developing the photoresist, the wafer is subjected to an etching process, whereby the layer is patterned according to the pattern on the mask. The remaining photoresist is then removed from the remaining parts of the layer. This process is repeated until all layers are deposited on the wafer.
• the mirrors used in projection exposure systems generally have a reflex coating made up of a plurality of individual layers, the reflection coefficient of which is frequently more than 90%.
• lenses and other refractive optical elements are provided with antireflection coatings in order to reduce light losses and aberrations due to unwanted double reflections at the interfaces of the refractive optical elements.
• an antireflection coating which has a difference in the reflection coefficients for s and p polarized light of less than 0.5% over an incident angle range between 0 ° and 50 °.
• JP 2004-302113 A discloses an antireflection coating suitable for projection exposure systems, which has a difference in the reflection coefficients for s and p polarized light of less than 1% over an incident angle range between 0 ° and 70 °. Over a part of the angular spectrum, the reflection coefficient R 3 for the s-polarized light is smaller than the reflection coefficient R p for the p-polarized light.
• EP 0 994 368 A2 discloses an antireflection coating suitable for projection exposure systems whose average reflectivity is less than 0.5% over an incident angle range between 0 ° and 46 ° and less than 2% up to incidence angles of approximately 56 °. At angles of incidence below 56 °, the difference of the reflection coefficients for s- and p-polarized light is less than about 0.3%. For incident angles above 56 °, however, both the mean reflectance and the difference of the reflection coefficients increase sharply; at 70 ° the difference is about 5%. Since incident angles of up to 70 ° can occur with particularly high-aperture projection lenses, depending on the lens shape and angles, this known antireflection coating does not meet the highest requirements.
• No. 6,628,456 B2 describes suitable antireflection coatings for projection exposure systems which have a low average reflectivity. Dependencies on the polarization state or angle of incidence are not considered there.
• antireflection coatings are known in which the phase splitting is particularly low. This is achieved by the use of form birefringent coatings, wherein the induced by the birefringence of the deceleration, the delay by different Fresnel Coefficients for the s and p components caused delay at least largely compensated.
• significant polarization dependencies of the reflectivity can also occur there for large incident angle ranges.
• US 2005/0254120 A1 discloses a catadioptric projection objective in which a first mirror has a coating which reflects the s-component of the projection light more strongly.
• a second mirror on the other hand, reflects the p component more strongly, as a result of which overall polarization independence is largely achieved.
• the object of the invention is to provide a projection exposure apparatus with optical elements whose (anti-) reflective coatings on the one hand are cost-effective and on the other hand do not appreciably affect the imaging properties of the projection objective.
• this object is achieved by a microlithographic projection exposure apparatus with an optical element which carries an antireflection coating to reduce the reflectivity.
• This is designed so that over an angle of incidence in the range of 0 ° to 70 °, the transmission coefficient of the antireflection coating for mutually orthogonal polarization states by not more than 10%, preferably not more than 3%, more preferably not more than 1%, from each other.
• the projection exposure apparatus has means for homogenizing an intensity distribution, which are preferably arranged in or in the vicinity of a field or pupil plane.
• the means for homogenizing the intensity distribution ensure that larger angular dependencies of the transmission coefficient or of the reflection coefficient, as can occur in polarization-optical optimization, do not affect the imaging properties in an intolerable manner. Homogenization of the intensity distribution in this context means that undesired fluctuations of the intensity distribution in the image plane are suppressed.
• the desired intensity distribution in the image plane is an equal distribution, so that in the absence of a mask all points are irradiated with the same intensity.
• the coatings may also be designed such that the small differences in the transmission or reflection coefficient for orthogonal
• Polarization states are not present for a single coating but the overall effect of several or even all of the coatings included in the projection exposure equipment.
• the individual optimization is thus replaced by an overall optimization.
• the means for homogenizing the intensity distribution ensure that larger angular dependencies of the transmission coefficient or the reflection coefficient do not affect the imaging properties in an intolerable manner.
• the means for homogenizing the intensity distribution may be gray filters, as are known per se in the prior art. It is particularly favorable if one or more gray filters is or are specifically adapted to the coating (or the entirety of all coatings).
• the gray filter e.g. may be formed as a simple transmission filter, it may for example be designed so that only caused by the coating fluctuations in the intensity distribution can be compensated. Variations in the intensity distribution due to other causes can be detected, for example. be reduced by other, preferably adjustable filters or other means.
• the present invention furthermore relates to antireflection coatings having particularly advantageous polarization-optical properties.
• antireflection coatings are proposed in which both the reflection coefficients and the phase depend only slightly on the polarization state.
• Other antireflection coatings have the property that the reflection coefficient for p-polarized light is greater over a certain angle of incidence range than for s-polarized light, or that p-polarized light delays the antireflection over s-polarized light within a certain angle of incidence range Coating passes through. This makes it possible to combine several reflective or antireflection coatings so that overall results in a polarization-neutral behavior.
• the coatings are characterized in that they only have layers with a packing density of more than 85% and therefore are very durable.
• FIG. 1 shows a meridional section through a projection exposure apparatus according to the invention
• Figure 2 is a sectional view (not to scale) of a lens with an antireflection coating according to an embodiment of the invention
• FIG. 3 shows a graph in which the average transmittance as a function of the angle of incidence is plotted for the embodiment of an antireflection coating shown in FIG.
• FIG. 4 shows a graph in which the difference of the transmission coefficients for s- and p-polarized light as a function of the angle of incidence is plotted for the exemplary embodiment shown in FIG.
• FIG. 5 shows a graph in which, for the exemplary embodiment shown in FIG. 2, the phase difference between s- and p-polarized light is plotted as a function of the angle of incidence;
• FIGS. 6 to 9 are graphs in which, for antireflection
• the reflection coefficients for s-polarized, p-polarized or nonpolar light are applied as a function of the angle of incidence;
• FIGS. 10 and 11 are graphs in which for antireflection
• the reflection coefficients for s-polarized, p-polarized or unpolarized light and the phase difference are plotted as a function of the angle of incidence.
• FIG. 1 shows a meridional section through a microlithographic projection exposure apparatus, generally designated 10, in a highly schematized and not to scale representation.
• the projection exposure apparatus 10 has an illumination system 12 with a light source 14 for generating a projection light bundle 13.
• the wavelength of the projection light is 193 nm.
• the illumination system 12 further includes an illumination optics indicated by 16 with a depolarizer 17 and a field stop 18.
• the illumination optics 16 forms the projection light beam generated by the light source 14. del in the desired manner and allows the setting of different illumination angle distributions.
• the illumination optics 16 may contain, for example, exchangeable diffractive optical elements and / or microlens arrays. Since such illumination optics 16 are known in the prior art, see for example US 6 285 443 A, the explanation of further details can be omitted here.
• An objective 19 of the illumination system 12 sharpens the field diaphragm 18 to a subordinate object plane of a projection objective 20.
• the projection objective 20 contains a large number of lenses and other optical elements, of which only a few are shown by way of example in FIG. 1 and designated L 1 to L 6 for the sake of clarity.
• the projection lens 20 may also comprise other optical elements, e.g. imaging or the folding of the beam path serving mirrors or filter elements containing.
• the projection objective 20 contains exclusively mirrors as imaging elements, since there are no sufficiently transparent lens materials available for these short wavelengths. The same applies to the lighting system 12.
• the projection objective 20 is used to arrange an object that can be arranged in an object plane 22 of the projection objective 20 diminished by the projection light beam 13 mask 24 image on a photosensitive layer 26, which may be, for example, a photoresist.
• the layer 26 is located in an image plane 28 of the projection objective 20 and is applied to a carrier 29, for example a silicon wafer.
• the lenses contained in the illumination system 12 and the projection objective 20 are provided with an antireflection coating.
• the purpose of the antireflective coating is to reduce the proportion of light that is reflected at the interfaces of the lenses and thus lost for projection or leads to double reflections.
• the coatings usually contain a plurality of thin individual layers, the refractive indices and thicknesses of which are selected so that the desired properties are achieved for the wavelength of the projection light 13.
• the antireflective exposures applied to the lenses that they have these optical properties independently of the polarization state of the incident projection light 13. If the transmissivity for orthogonal polarization states varies too much in the case of an antireflection coating, this polarization dependence can lead to undesired aberrations. This is due to the fact that despite the use of a depolarizer 17 in the illumination system 12, the projection light 13 does not remain completely depolarized when passing through the projection objective 20. This may be due to e.g. intrinsically or stress-birefringent lens materials, polarizing mask structures as well as the polarization dependencies under consideration in antireflection and reflex coatings.
• an antireflection coating is arranged in the vicinity of a focusing plane, then the polarization dependence of its transmittance leads to intensities that fluctuate over the field of view when the projection light has a varying polarization preferential direction across the field. Such intensity fluctuations in a field level are noticeable on the component as unwanted field-dependent structure width fluctuations. Is an antireflection coating with polarization-dependent transmissivity onshack, however, arranged close to the pupil, an already existing angular dependence of the polarization state can also lead to undesirable structure width fluctuations.
• (Anti-) reflective coatings of lenses and mirrors can also cause the phase of the light passing through the coatings to change depending on the polarization state. In this way, the coating becomes optically birefringent, which has an unfavorable effect on the image quality in the image plane. Therefore, the allowable phase difference ⁇ between orthogonal polarization states should be less than 1/10 of the wavelength ⁇ of the projection light 13.
• a high average transmittance, on the one hand, and a low polarization dependence of the transmissivity and the phase, on the other hand, over a larger angle of incidence range can not be realized, or at most, at great expense.
• the coatings in the projection exposure apparatus 10 are therefore designed so that the Polarization dependence of the transmission coefficient and the phase over a large angle of incidence range is kept low.
• the average transmittance and the middle phases can vary noticeably over the angle of incidence range.
• the associated disturbances of the image are corrected in a comparatively simple manner, for example with the aid of gray filters or - in the case of phase errors - local rotationally asymmetric surface deformations.
• extensive polarization independence means that the transmission coefficients for mutually orthogonal polarization states are not more than 10%, preferably not more than 3%, more preferably not more than 1%, from each other over an incident angle range of 70 ° away from each other.
• reflex coatings for the reflection coefficient are not more than 10%, preferably not more than 3%, more preferably not more than 1%, from each other over an incident angle range of 70 ° away from each other.
• FIG. 2 shows, in a lateral section, an embodiment of an antireflection coating 32 in which the transmission coefficients for mutually orthogonal polarization states do not differ by more than 1%.
• the antireflection coating 32 consists of 6 individual thin layers L 1 to L 6 whose material and optical thicknesses are specified in Table 1.
• the quantity QWOT quarter wave optical thickness denotes the optical thickness, ie the product of refractive index and geometric thickness, in units of a quarter wavelength.
• EP 0 994 368 A2 also mentioned at the outset, describes a more stable coating of five layers, in which, however, the transmission coefficients for orthogonal polarization states deviate from one another by about 5% in the stated angle of incidence range from 0 ° to 70 °. It is assumed below that the light beam 30 includes both a p-polarized component 38 indicated by double arrows and an s-polarized component indicated by black circles 40.
• the reflectivity of the antireflection coating 32 also differs depending on the polarization state of the incident light, which is indicated in FIG. 2 in an exaggerated manner at 44.
• FIGS 3, 4 and 5 show graphs in which for the antireflection coating 32 the average transmittance (r), the difference of the transmission coefficients
• a field diaphragm in the illumination system 12 which comprises a multiplicity of individually movable diaphragm elements.
• Such per se known field diaphragms make it possible to change the radiation dose in the image plane 28 as a function of the longitudinal position of the slit-shaped light field.
• the antireflection coating 32 is located near a pupil plane, this will produce a pupil apodization.
• Such pupil apodizations can be corrected with suitably designed antireflective layers near a pupil plane.
• a tilt of the pupil apodization which can be described by the Zernike coefficients Z2 / Z3, can be corrected with a mirror layer. Stronger double reflections, which can occur as a result of the mean transmittance (T ⁇ , which is lower at certain angles, can be intercepted with scattering stops.
• phase errors resulting from the antireflection coating 32 can lead to aberrations.
• Such aberrations can be corrected with known manipulators, at least within certain limits.
• a particularly good correction succeeds when interfaces of optical elements or specially provided here plates are deformed locally and non-rotationally symmetrical.
• the deformations which can be produced by material accumulation or removal are on the order of a few nanometers, preferably below 50 nanometers.
• an overall optimization of several or all of the antireflection coatings contained in the projection objective 20 and optionally in the entire projection exposure apparatus 10 can also be undertaken.
• the above conditions can then be considered ⁇ T total ⁇ 10%, preferably ⁇ 3%, more preferably ⁇ 1% and
• Table 2 gives the layer specification for an embodiment of an antireflection coating which has a total of four layers.
• FIG. 6 shows a graph in which the reflection coefficients R 3 , R p and R a for s-polarized, p-polarized or unpolarized light as a function of the angle of incidence are plotted for this antireflection coating.
• the layers are counted from the substrate, which may be, for example, a lens or a plane-parallel plate.
• the material of the carrier (substrate) CaF 2 is assumed, which has a refractive index of about 1.56 at a wavelength of 193 nm.
• other support materials for example synthetic quartz glass (SiO 2 ) or barium fluoride (BaF 2 ) are used; the optical properties of the antireflection coating are thereby changed only relatively slightly.
• the material used for the higher refractive layers was lanthanum fluoride (LaF 3 ), which has a refractive index of about 1.69 at a wavelength of 193 nm.
• magnesium fluoride (MgF 2 ) was assumed to have a refractive index of about 1.43 at the same wavelength.
• the materials mentioned for the higher refractive layers and the lower refractive layers can also be replaced by other materials each having similar refractive indices.
• higher refracting materials in addition to LaF 3 in particular NdF 3 Al 2 O 3 and ErF 3 are suitable.
• MgF 2 for example, AlF 3
• chiolite or cryolite are also suitable for the lower refractive materials. Since these materials have slightly different refractive indices than the materials mentioned in Table 2, deviations may result for the optical thicknesses given there in units of QWOT (quarter wave optical thickness). These are listed in the last line of Table 2 in the form of range data. Even with the use of LaF 3 and MgF 2 it may be useful to have optical thicknesses within the Use ranges of values, for example, to fine-tune.
• the reflection coefficients R 3 and R p for s-polarized and p-polarized light, respectively are over an incident angle range between 0 ° and 60 ° ° only very slightly, not more than 1%, from each other.
• the absolute value of the reflection coefficients R 3 and R p is below 1%.
• a peculiarity of this antireflection coating is that for angles of incidence between about 35 ° and 55 °, the reflection coefficient R 3 for s-polarized light is less than the reflection coefficient R p for p-polarized light.
• the first time in the aforementioned JP 2004-302113 - but for an incident angle range above 55 ° - has been described, is unusual because, according to the Fresnel equations p-polarized light is generally better transmitted than s-polarized light.
• the antireflection coatings whose polarization dependencies should compensate themselves, the behavior described in have the same incident angle range. Beams of light incident on one optical surface at large angles of incidence may strike another optical surface at small angles of incidence and vice versa. If two identically constructed antireflection coatings, which have regions with R 3 > R p and R 3 ⁇ R p , are applied to optical surfaces selected in this way, their polarization dependencies can be mutually neutralized.
• the simplest conditions are usually when the compensating antireflection coatings are applied to the entrance and exit surfaces of an optical element, eg a lens.
• an optical element eg a lens.
• the angles of incidence on the entrance and exit surfaces of the optical lenses are similarly interpreted.
• numerous other optical elements lie between the antireflection coatings, the angle of incidence distribution can change in a relatively complicated manner due to the optical elements located therebetween.
• the layer specification listed in Table 2 need not be the same over the entire surface of the optical element. Since different areas on an optical element are often exposed to different distributions of angles of incidence, it may be useful to have different antireflection coatings on the different areas apply, which are optimally adapted to the occurring angle spectrum.
• Table 3 shows the layer specification for an embodiment of an antireflection coating which has a total of eight layers.
• FIG. 7 shows a graph in which the reflection coefficients R 3 , R p and R a for s-polarized, p-polarized or unpolarized light as a function of the angle of incidence are plotted for this antireflection coating.
• An essential advantage over the antireflection coating described in JP 2004-302113 is, above all, that in the antireflection coating described here only layers are used which have a packing density of more than 85%.
• the packing density of the lowermost layer is only 49% in order to be able to realize the low refractive index of 1.21.
• Such a low packing density is disadvantageous because such a less compact layer is susceptible to environmental influences and therefore relatively quickly changes its optical properties in terms of time.
• FIG. 8 shows a graph in which this antireflection coating the reflection coefficients for s-polarized, p-polarized and unpolarized light are plotted as a function of the angle of incidence.
• the reflection coefficients for s-polarized and p-polarized light differ only very slightly, namely by not more than about 0.1%.
• the absolute values for the reflection coefficients R s and R p are also very small in an angle range between about 20 ° and 50 ° with less than 4%.
• this antireflection coating is suitable in particular for those optical elements in which light impinges only or at least predominantly obliquely with angles of incidence in said region.
• the antireflection coating with the layer specification given in Table 4 has also been optimized with regard to the lowest possible phase difference ⁇ between s-polarized and p-polarized To achieve light after the passage of the antireflection coating.
• ⁇ phase difference
• the coating consists of as few layers as possible, but at least the thickness of the layers present is as small as possible.
• a phase difference was achieved, which is smaller for incident angles between 0 ° and 50 ° than 0.5 ° and only at an angle of incidence of 70 ° to about 6 °.
• the antireflection coating is particularly suitable for angles of incidence between 0 ° and about 40 °.
• the reflection coefficients R s and R p for s-polarized and p-polarized light are both below about 0.2%; the difference ⁇ R between the reflection coefficients is smaller by approximately one order of magnitude.
• the phase difference ⁇ also shifts to smaller incident Angle. Therefore, the phase difference ⁇ is slightly higher at incident angles of 70 °, namely at 10 °.
• the phase splitting can be reduced, if it is possible to make thinner, especially the thicker layers.
• Table 5 shows the layer specification for an antireflex coating, which starts from the layer specification for embodiment 3 shown in Table 3.
• FIG. 10 shows a graph in which the reflection coefficients for s-polarized, p-polarized and unpolarized light as a function of the angle of incidence are plotted for this antireflection coating.
• the Phase difference ⁇ for the embodiment 5 is plotted with dashed line and for the embodiment 3 for comparison with thin dash-dotted lines. It can be seen clearly that the reduction of the layer thicknesses also results in considerably smaller phase differences ⁇ for angles of incidence of more than approximately 30 °. In return, the reflection behavior has not significantly deteriorated by the modification made, we show a comparison of Figures 10 and 7.
• FIG. 11 shows a graph corresponding to FIG. 10, in which the reflection coefficients for p-polarized, s-polarized and unpolarized light and the phase difference ⁇ are plotted as a function of the angle of incidence.
• the antireflection coating according to this embodiment is characterized by a particularly small phase difference, the absolute value of which does not exceed 5 ° over the entire incident angle range between 0 ° and 70 °. It is also noteworthy in this antireflection coating that the phase difference ⁇ is negative in an angle range between 0 ° and about 65 °. This means that within this angular range p-polarized light with respect to the s-polarized light retarded passes through the antireflection coating. This unusual behavior can be used to compensate for a positive phase difference in a manner similar to that explained above in connection with Embodiment 2 for the reflection coefficients R s , R p . Again, the combination of at least one antireflection coating with positive phase difference with another antireflection coating with negative phase splitting can achieve that s-polarized and p-polarized light can be achieved after the passage of both antireflection coatings.

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• 2005
  • 2005-09-03 DE DE102005041938A patent/DE102005041938A1/de not_active Withdrawn
• 2006
  • 2006-09-04 WO PCT/EP2006/008605 patent/WO2007025783A2/de not_active Ceased
  • 2006-09-04 KR KR1020087005239A patent/KR20080039469A/ko not_active Ceased
  • 2006-09-04 JP JP2008528432A patent/JP2009507366A/ja not_active Ceased
• 2008
  • 2008-02-14 US US12/031,595 patent/US20080297754A1/en not_active Abandoned
• 2011
  • 2011-05-20 US US13/112,357 patent/US9733395B2/en not_active Expired - Fee Related
• 2014
  • 2014-07-15 US US14/331,392 patent/US20140320955A1/en not_active Abandoned
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