Method and apparatus for chemically treating a surface

Abstract

The invention relates to a method for chemically treating a surface (32) by application of a chemically reactive fluid (38), in particular a surface (32) of a substrate (31) of a component (Mx, 117) of a projection exposure apparatus (1, 101) for semiconductor lithography, characterized in that the chemical treatment by the reactive fluid (38) is limited to a given area (36) by application of an additional fluid (39) to this area (36). The invention further relates to an apparatus (30) for chemically treating at least one surface (32) comprising a spray array with at least two spray units (34, 35) for applying a fluid (38, 39). The apparatus (30) is characterized in that a first spray unit (34) is embodied such that a first area (36) of the surface (32) is treated with the reactive fluid (38) and a second spray unit (35) is embodied such that a second area (37) of the surface (32) is treated with the additional fluid (39).

Description

[Technical field]

[0001] This application claims priority from German Patent Application No. 10 2022 203 298.5 of January 4, 2022, the contents of which are incorporated herein by reference in their entirety.

[0002] The present invention relates to a method and device for the chemical treatment of a surface, in particular of a substrate intended for a component of a projection exposure apparatus for semiconductor lithography. [Background technology]

[0003] Such substrates may in particular be part of optical components such as mirrors used for imaging or illumination of masks. To produce layer structures on such substrates, photolithography processes are often used, in which a radiation-sensitive coating such as a photoresist is applied to the surface to be structured, and then exposed to electromagnetic radiation using a mask or a locally applied beam writer, followed by development. In this way, the desired structures can be produced on the substrate.

[0004] The coating can be irradiated here with wavelengths in the range of about 500 nm or less. Subsequent development dissolves the exposed areas to generate the desired structure in the coating. Since uniform and complete removal of the coating is essential for further work steps, high demands are placed on the development rate across the substrate, i.e. the amount of coating dissolved per unit time. The development of the coating is a heterogeneous chemical reaction that can be carried out by spraying or jetting a chemically reactive fluid onto the substrate from a single spray unit or a collection of spray units, such as an array. Here, for example, a movable spray unit can be spatially displaced in at least two dimensions relative to the surface.

[0005] To ensure a uniform reaction, i.e., development of a coating, in time and space over the surface to be treated, which is larger than the range of the spray unit of the reactive fluid, the chemical reactive fluid must be continuously exchanged or renewed at the site to be treated. A drawback of such a method is the uncontrolled flow behavior of the reactive fluid on the surface to be treated, especially outside the area directly wetted by the spray unit, mainly caused by gravity and / or the topography of the surface to be developed. This leads to spatial and temporal uncertainty in the development rate of the surface.

[0006] This effect is disadvantageously intensified when the method is applied to substrates of components of projection exposure apparatus for semiconductor lithography, which for example have a macroscopic spherical or aspherical surface on which a macroscopic freeform surface is partially superimposed. Summary of the Invention [Problem to be solved by the invention]

[0007] It is an object of the present invention to provide a method and apparatus which obviates each of the above-mentioned disadvantages of the prior art. [Means for solving the problem]

[0008] This object is achieved by a method and an arrangement having the features of the independent claims. The dependent claims relate to advantageous developments and modifications of the invention.

[0009] The method according to the invention for chemically treating a surface by application of a chemically reactive fluid is characterized in that the chemical treatment with the reactive fluid is limited to a defined area by application of an additional fluid. This has the advantage that the reaction dynamics of the reactive fluid, for example in the form of a developer, can be controlled with high spatial precision. The limited area moves over the surface so that the entire surface of the substrate can be chemically treated in a defined manner. The movement of the area over the surface can therefore be used to control the temporal aspects of the chemical reaction in addition to the spatial control of the chemical reaction. In short, a very high predictability of the reaction dynamics of the chemical treatment on the surface, i.e. the development rate, can be achieved and the development of the coating can be controlled with high spatial and temporal precision.

[0010] In a first embodiment, the predetermined area can be restricted by neutralizing the action of the reactive fluid. The additional fluid can be applied to the surface such that there are two areas on the surface with different fluids. At the contact area of ​​the two areas, the fluids mix, thereby neutralizing the chemical action of the reactive fluid, such as a developer for a coating. By treating the area treated with the reactive fluid with an additional fluid due to the relative movement of the device with respect to the surface, the chemical action of the reactive fluid can be neutralized as well.

[0011] In particular, the additional fluid may be embodied as a neutralizing fluid, i.e. capable of preventing chemical reactions, in particular chemical reactions induced as a result of the chemical properties of the reactive fluid.

[0012] Furthermore, the additional fluid may be embodied as a dilution fluid, which neutralizes the action of the reacting fluid by diluting the reacting fluid, rather than preventing the chemical reaction itself, so that the chemical reaction is slowed down and no longer has the desired reaction rate, and is thereby neutralized.

[0013] In yet another embodiment of the method, the predetermined area can be limited by displacing the reactive fluid. The surface of the substrate can be treated with an additional fluid such that the displacement can limit the area of ​​the location treated with the reactive fluid. The additional fluid can have physical properties such that even if the additional fluid is applied to an area already wetted with the reactive fluid, displacement of the reactive fluid occurs instead of mixing with the reactive fluid.

[0014] In particular, the additional fluid may be embodied as a displacement fluid.

[0015] Additionally, the displacement fluid may include dry air, which may displace the reactant fluid from the surface and may be embodied, for example, in the form of an air knife, i.e., a linear air jet.

[0016] In yet another embodiment of the invention, at least one first spray unit is capable of treating a first area of ​​the surface with a reactive fluid and at least one second spray unit is capable of treating a second area of ​​the surface with an additional fluid.

[0017] In particular, the two locations may be adjacent to each other. At the interface, the reaction rate of the reactive fluid may be reduced as described above. A plurality of second spray units may be assigned to the first spray unit for the reactive fluid, thereby limiting the area wetted by the first spray unit with a large number of areas sprayed with additional fluid. A plurality of second spray units may also be assigned to an array of a plurality of first spray units for the reactive fluid.

[0018] Furthermore, the second spray unit can partially surround the first region. Depending on the design of the spray pattern of the nozzle of the second spray unit, the second spray unit can partially surround the first spray unit. In the case of multiple second spray units, each second region can partially surround the first region.

[0019] In particular, the second region can completely surround the first region, resulting in complete spatial control over the extent of the first region that is wetted by the reactive fluid.

[0020] Furthermore, the two regions can overlap, which can favor the edges of the coating, as the reaction dynamics decrease continuously toward the edge of the region, especially when the reacting fluid is limited by dilution as described above.

[0021] In particular, the surface may be located on an optical element.

[0022] Furthermore, the surface can be spherical or aspherical and / or can at least partially have a freeform surface. The surface here can have a macroscopic spherical or aspherical shape and / or can have a microscopic freeform surface superimposed thereon.

[0023] The method can be advantageously used for treating substrates of components of projection exposure apparatus for semiconductor lithography, as already mentioned, but in principle the method can be used for relevant applications in virtually all technical fields.

[0024] The device according to the invention for chemically treating at least one surface comprises a spray array with at least two spray units for applying a fluid, characterized in that a first spray unit is embodied such that a first area of ​​the surface is treated with a reactive fluid and a second spray unit is embodied such that a second area of ​​the surface is treated with an additional fluid.

[0025] Furthermore, the device may comprise a drying unit, which may effectively prevent wetting of certain areas of the surface, especially areas that should not be wetted. Alternatively, the drying unit may completely prevent the reaction dynamics of the reactive fluids by drying, in which case the initial concentration of the reactive fluids as a result of drying must be taken into account.

[0026] In particular, the drying unit can be embodied as an air knife, which, as already mentioned above, can be used on the one hand for drying, but also for displacing and therefore limiting an area on the surface.

[0027] Furthermore, the device can comprise a suction unit, which can be arranged in the air knife or in front of the air knife in the direction of movement and can suck up the fluid located on the surface. The reactive fluid loses its chemical reaction dynamics due to the reaction with the coating and is therefore renewed intermittently. As a result of the suction, a flow can occur in the first area from the central point to be treated with fresh reactive fluid to the edge of the area. There, first the reactive effect of the reactive fluid is neutralized or attenuated, and then the reactive fluid is sucked up by the suction unit. The air knife ensures that no fluid remains outside the area being treated on the surface. Alternatively, the area on which the reactive fluid acts can be limited only by the air knife and the suction unit.

[0028] Furthermore, the apparatus may comprise at least one sensor for detecting the topography of the surface. The sensor may be arranged to detect the surface before the coating is wetted and send a signal to an actuator of the apparatus. The actuator may determine a parameter of the spray unit from the detection signal, thereby enabling a development rate optimized to the actual topography of the surface.

[0029] Exemplary embodiments and variants of the invention are explained in more detail below with reference to the drawings. [Brief description of the drawings]

[0030] [Figure 1] 1 shows a schematic meridian section of a projection exposure apparatus for EUV projection lithography; [Diagram 2] 1 shows a schematic meridian section of a projection exposure apparatus for EUV projection lithography; [Figure 3a] 1 shows a schematic diagram of the present invention. [Figure 3b] 1 shows a schematic diagram of the present invention. [Figure 4] Yet another embodiment of the present invention is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] In the following text, the essential components of a projection exposure apparatus 1 for microlithography are firstly described by way of example with reference to Figure 1. The description here of the basic arrangement of the projection exposure apparatus 1 and its components should not be understood as limiting.

[0032] An embodiment of the illumination system 2 of the projection exposure apparatus 1 comprises, in addition to the radiation source 3, an illumination optical unit 4, which illuminates an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a separate module from the rest of the illumination system. In this case, the illumination system does not include the light source 3.

[0033] A reticle 7 arranged in the object field 5 is illuminated. The reticle 7 is held by a reticle holder 8. The reticle holder 8 is displaceable in particular in the scanning direction by a reticle displacement drive 9.

[0034] For illustrative purposes, a Cartesian xyz coordinate system is shown in Figure 1. The x direction runs perpendicular to the plane of the drawing. The y direction runs horizontally and the z direction runs vertically. In Figure 1, the scanning direction runs along the y direction. The z direction runs perpendicular to the object plane 6.

[0035] The projection exposure apparatus 1 comprises a projection optical unit 10. The projection optical unit 10 serves to image the object field 5 into an image field 11 in an image plane 12. The image plane 12 extends parallel to the object plane 6. Alternatively, angles other than 6° between the object plane 6 and the image plane 12 are also possible.

[0036] The structures on the reticle 7 are imaged onto a photosensitive layer of a wafer 13, which is arranged in the region of the image field 11 of the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 is displaceable, in particular along the y direction, by a wafer displacement drive 15. The displacement of the reticle 7 by the reticle displacement drive 9 on the one hand and the displacement of the wafer 13 by the wafer displacement drive 15 on the other hand can be performed synchronously with respect to one another.

[0037] The radiation source 3 is an EUV radiation source. The radiation source 3 in particular emits EUV radiation 16, also referred to in the following as working radiation, illumination radiation or illumination light. In particular, the working radiation has a wavelength in the range of 5 nm to 30 nm. The radiation source 3 may be a plasma source, such as a Laser Produced Plasma (LPP) source or a GDPP source, i.e. a Gas Discharge Plasma (DPP) source. It may also be a synchrotron-based radiation source. The radiation source 3 may be a Free Electron Laser (FEL).

[0038] The illumination radiation 16 coming from the radiation source 3 is focused by a collector 17. The collector 17 may be a collector with one or more ellipsoidal and / or hyperbolic reflecting surfaces. The illumination radiation 16 may be incident on at least one reflecting surface of the collector 17 at grazing incidence (GI), i.e. at an angle of incidence greater than 45° relative to the direction of the normal to the mirror surface, or at normal incidence (NI), i.e. at an angle of incidence smaller than 45°. The optical surfaces of the collector 17 may be structured and / or coated, on the one hand, to optimize the reflectivity for the radiation used and, on the other hand, to suppress extraneous light.

[0039] After the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 may represent the separation between the source module, which includes the radiation source 3 and the collector mirror 17, and the illumination optics unit 4.

[0040] The illumination optical unit 4 comprises a deflection mirror 19 and, downstream in the beam path, a first facet mirror 20. The deflection mirror 19 can be a plane deflection mirror or a mirror with a speed-of-light-influencing effect beyond a pure deflection effect. Alternatively or additionally, the deflection mirror 19 can be implemented as a spectral filter, which separates the used optical wavelength of the illumination radiation 16 from extraneous light of wavelengths outside it. If the first facet mirror 20 is arranged in a plane of the illumination optical unit 4 that is optically conjugate with the object plane 6 as a field plane, it is also referred to as a field facet mirror. The first facet mirror 20 comprises a plurality of individual first facets 21, also referred to as field facets in the following. FIG. 1 shows only some of these facets 21 by way of example.

[0041] The first facet 21 may be embodied as a macroscopic facet, in particular as a rectangular facet or as a facet having an arcuate or part-circular peripheral contour. The first facet 21 may be embodied as a planar facet or as a convexly or concavely curved facet.

[0042] The first facet 21 itself can also consist of a number of individual mirrors, in particular a number of micromirrors, as is known, for example, from DE 10 2008 009 600. The first facet mirror 20 can in particular be embodied as a microelectromechanical system (MEMS system). See DE 10 2008 009 600 for further details.

[0043] Between the collector 17 and the deflection mirror 19, the illumination radiation 16 travels horizontally, ie along the y direction.

[0044] In the beam path of the illumination optical unit 4, a second facet mirror 22 is arranged downstream of the first facet mirror 20. If the second facet mirror 22 is arranged in a pupil plane of the illumination optical unit 4, it is also referred to as a pupil facet mirror. The second facet mirror 22 can also be arranged away from the pupil plane of the illumination optical unit 4. In this case, the combination of the first facet mirror 20 and the second facet mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006 / 0132747, EP 1 614 008 and US 6,573,978.

[0045] The second facet mirror 22 includes a plurality of second facets 23. In the case of a pupil facet mirror, the second facets 23 are also referred to as pupil facets.

[0046] The second facet 23 may likewise be a macroscopic facet, which may for example have a circular, rectangular or hexagonal perimeter, or may be a facet made up of a micromirror. In this respect, reference is likewise made to DE 10 2008 009 600 A1.

[0047] The second facet 23 may have a planar reflective surface or a convexly or concavely curved reflective surface.

[0048] The illumination optical unit 4 therefore forms a double-faceted system. This basic principle is also called a fly's eye integrator.

[0049] It may be advantageous not to arrange the second facet mirror 22 exactly in a plane that is optically conjugate with the pupil plane of the projection optical unit 10. In particular, the pupil facet mirror 22 may be arranged tilted with respect to the pupil plane of the projection optical unit 10, as described, for example, in DE 10 2017 220 586 A1.

[0050] The individual first facets 21 are imaged into the object field 5 by means of a second facet mirror 22. The second facet mirror 22 is the last beam-shaping mirror in the beam path before the object field 5 or indeed the final mirror for the illumination radiation 16.

[0051] In yet another embodiment (not shown) of the illumination optical unit 4, a transfer optical unit, which in particular contributes to the imaging of the first facet 21 into the object field 5, can be arranged in the beam path between the second facet mirror 22 and the object field 5. The transfer optical unit can have exactly one mirror or two or more mirrors arranged one after the other in the beam path of the illumination optical unit 4. The transfer optical unit can in particular comprise one or two normal incidence mirrors (NI mirrors) and / or one or two grazing incidence mirrors (GI mirrors).

[0052] In the embodiment shown in FIG. 1, the illumination optical unit 4 comprises exactly three mirrors downstream of the collector 17 , in particular a deflection mirror 19 , a field facet mirror 20 and a pupil facet mirror 22 .

[0053] In yet another embodiment of the illumination optical unit 4, the deflection mirror 19 can also be omitted, so that the illumination optical unit 4 can then have exactly two mirrors after the collector 17, in particular a first facet mirror 20 and a second facet mirror 22.

[0054] The imaging of the first facet 21 onto the object plane 6 by the second facet 23 or by means of the second facet 23 and the transfer optical unit is generally only an approximate imaging.

[0055] The projection optical unit 10 comprises a number of mirrors Mi, which are numbered according to their position in the beam path of the projection exposure apparatus 1 .

[0056] In the example shown in Fig. 1, the projection optical unit 10 comprises six mirrors M1-M6. A substitution of 4, 8, 10, 12 or any other number of mirrors Mi is likewise possible. The penultimate mirror M5 and the last mirror M6 each have a passing aperture for the illumination radiation 16. The projection optical unit 10 is a double-shielded optical unit. The projection optical unit 10 has an image-side numerical aperture which is greater than 0.5, may be greater than 0.6, and may for example be 0.7 or 0.75.

[0057] The reflective surface of the mirror Mi can be in the form of a freeform surface without an axis of rotational symmetry. Alternatively, the reflective surface of the mirror Mi can be designed as an aspheric surface with exactly one axis of rotational symmetry of the reflective surface shape. Like the mirrors of the illumination optical unit 4, the mirror Mi can include coatings that are highly reflective with respect to the illumination radiation 16. These coatings can in particular be in the form of multilayer coatings with alternating layers of molybdenum and silicon.

[0058] The projection optical unit 10 has a large object-image offset in the y direction between the y coordinate of the center of the object field 5 and the y coordinate of the center of the image field 11. In the y direction, this object-image offset may have approximately the same magnitude as the z distance between the object plane 6 and the image plane 12.

[0059] The projection optical unit 10 can have, in particular, an anamorphic form. In particular, it has different imaging scales βx, βy in the x-direction and the y-direction. The two imaging scales βx, βy of the projection optical unit 10 are preferably (βx, βy)=(+ / -0.25, + / -0.125). A positive imaging scale β means imaging without image inversion. A negative sign of the imaging scale β means imaging with image inversion.

[0060] The projection optical unit 10 results in a size reduction in the x-direction, ie perpendicular to the scanning direction, by a ratio of 4:1.

[0061] The shadow optical unit 10 provides a size reduction of 8:1 in the y-direction, ie the scanning direction.

[0062] Other imaging scales are possible as well. Imaging scales of the same sign and the same absolute value in the x and y directions, for example 0.125 or 0.25, are also possible.

[0063] The number of intermediate image planes in the x- and y-directions in the beam path between the object field 5 and the image field 11 may be the same or may differ depending on the design of the projection optical unit 10. An example of a projection optical unit with a different number of such intermediate images in the x- and y-directions is known from US 2018 / 0074303.

[0064] Each of the pupil facets 23 is assigned to exactly one of the field facets 21 in order to respectively form an illumination channel which illuminates the object field 5. In particular, this makes it possible to obtain an illumination according to the Köhler principle. The far field is decomposed into a number of object fields 5 by means of the field facets 21. The field facets 21 generate a number of images of intermediate foci on the respectively assigned pupil facets 23.

[0065] The field facets 21 are imaged onto the reticle 7 in an overlapping manner by means of the respectively assigned pupil facets 23 in order to illuminate the object field 5. The illumination of the object field 5 is in particular as uniform as possible. Its uniformity error is preferably less than 2%. By overlapping the different illumination channels, field uniformity can be obtained.

[0066] The illumination of the entrance pupil of the projection optical unit 10 can be geometrically defined by the arrangement of the pupil facets. By selecting the illumination channels, and in particular the subset of pupil facets, which guide the light, the intensity distribution in the entrance pupil of the projection optical unit 10 can be set. This intensity distribution is also called the illumination setting.

[0067] An equally favorable pupil uniformity in the region of a defined illumination portion of the illumination pupil of the illumination optical unit 4 can be achieved by redistribution of the illumination channels.

[0068] Further aspects and details of the illumination of the object field 5, in particular the entrance pupil of the projection optical unit 10, are explained below.

[0069] The projection optical unit 10 may in particular have a concentric entrance pupil. It may be accessible. It may also be inaccessible.

[0070] The entrance pupil of the projection optical unit 10 generally cannot be illuminated exactly by means of the pupil facet mirror 22. In the case of imaging of the projection optical unit 10 telecentrically imaging the centre of the pupil facet mirror 22 onto the wafer 13, the aperture rays often do not intersect at a single point. However, it is possible to find a surface for which the determined separation of the pair of aperture rays is minimal. This surface represents the entrance pupil or a surface conjugate thereto in real space. In particular, this surface exhibits a finite curvature.

[0071] The projection optical unit 10 may have different entrance pupil positions for the tangential and sagittal beam paths. In this case, an imaging element, in particular an optical component of the transfer optical unit, should be provided between the second facet mirror 22 and the reticle 7. This optical element can be used to take into account the different positions of the tangential and sagittal entrance pupils.

[0072] In the arrangement of the components of the illumination optical unit 4 shown in Fig. 1, the pupil facet mirror 22 is arranged in a plane conjugate with the entrance pupil of the projection optical unit 10. The field facet mirror 20 is arranged at an inclination with respect to the object plane 6. The first facet mirror 20 is arranged at an inclination with respect to the arrangement plane defined by the deflection mirror 19.

[0073] The first facet mirror 20 is disposed at an angle with respect to a placement plane defined by the second facet mirror 22 .

[0074] FIG. 2 shows diagrammatically a meridian section of yet another projection exposure apparatus 101 for DUV projection lithography, in which the invention can also be used.

[0075] The structure and imaging principle of the projection exposure apparatus 101 are comparable to those described in Fig. 1. Identical components are designated by reference numbers which are increased by 100 compared to Fig. 1, i.e. the reference numbers in Fig. 2 start with 101.

[0076] 1, since the wavelength of the DUV radiation 116 used as the light used is large, in the range of 100 nm to 300 nm, in particular about 193 nm, refractive, diffractive and / or reflective optical elements 117, such as lens elements, mirrors, prisms, end plates, etc., can be used for imaging or illumination in the DUV projection exposure apparatus 101. The projection exposure apparatus 101 essentially comprises in this case an illumination system 102, a reticle holder 108 which receives and accurately positions a reticle 107 provided with structures which determine the subsequent structure on a wafer 113, a wafer holder 114 which holds, moves and accurately positions said wafer 113, and a projection lens 110 with a number of optical elements 117, which are held by mounts 118 in a lens housing 119 of the projection lens 110.

[0077] Illumination system 102 provides the DUV radiation 116 required for imaging reticle 107 onto wafer 113. A laser, plasma source, etc. can be used as the source of this radiation 116. The radiation 116 is shaped by optics in illumination system 102 so that upon incidence on reticle 107, the DUV radiation 116 has desired characteristics in terms of diameter, polarization, wavefront shape, etc.

[0078] Besides the additional use of refractive optical elements 117 such as lens elements, prisms, end plates, etc., the structure of the downstream projection optical unit 110 having a lens housing 119 does not fundamentally differ from the structure described in FIG. 1 and therefore will not be described in further detail.

[0079] FIG. 3a shows a cross-sectional view of the invention, exemplarily representing an optical element Mx, 117, for example as described with reference to FIGS. 1 and 2, in an apparatus 30 according to the invention. The optical element Mx, 117 comprises a substrate 31 with a surface 32 on which a coating 33 to be structured is formed. Instead of the optical element Mx, 177, naturally other bodies or elements for photolithographic structuring can also be processed in the apparatus 30. The apparatus 30 comprises, in the embodiment represented in FIG. 3a, a spray unit 34, which wets a first area 36 of the surface 32 with a reactive fluid in the form of a developer 38. As a result, the coating 33, which is exposed, for example by a lithographic process, is developed. Since the constancy of the development rate is important for the quality of the structuring of the coating 33, the reactive dynamics of the developer 38 must be controlled to be spatially and temporally uniform on the surface 32. On each side of the first spray unit 34, a second spray unit 35 is arranged. The second spray unit 35 wets the second region 37 that confines the first region 36 with additional fluid in the form of dilution fluid 39. The dilution of the developer 38 spatially confines the chemical reaction to the first region 36 by stopping or slowing down the chemical reaction of the developer 38 so that it does not cause a significant development rate. Alternatively or additionally, a neutralizing fluid can be used as an additional fluid to similarly confine the chemical reaction to the first region 36. As the substrate 31 is moved relative to the stationary device 30 on a positioning device, not shown, such as a robotic arm, the first region 36 moves over the surface 32, thereby developing the entire coating 33 on the surface 32. The distance of the spray units 34, 35 to the surface 32 affects the chemical reaction, as does the positioning of the coating 33 of the substrate 31 relative to gravity, the surface topography of the coating 33, and other parameters. The amount and concentration, i.e. reactivity, of the developer 38 and the amount of dilution fluid 39 are only some of the parameters of the spray units 34, 35 that contribute to the uniform development of the coating 33. The relative movement between the substrate 31 and the device 30 advantageously includes six degrees of freedom, and the tilt of the processing area on the surface 32 can also be adapted during the process, ensuring at least an approximately constant flow behavior of the fluids 38, 39 on the surface 32.Alternatively, the apparatus 30 can be moved relative to the substrate 31 or a combination of both methods can be selected, for example, such that the apparatus 30 moves linearly relative to the substrate 31 while the substrate is additionally rotated around at least one axis.

[0080] FIG. 3b shows a plan view of the surface 32 of the optical element Mx, 117. In addition to the centrally arranged first spray unit 34, the device 30 comprises, in the embodiment shown in FIG. 3b, ten second spray units 35 arranged rotationally symmetrically around the first spray unit 34. The areas 36, 37 wetted by the spray patterns of the individual spray units 34, 35 are shown as circles on the surface 32 of the substrate 31 in FIG. 3b. In addition to circular spray patterns, spray patterns of almost any shape can be used, such as full cone, flat jet and empty cone profiles. Furthermore, wetting can also be achieved by misting or jetting in addition to spraying. The first area 36 wetted with the developer 38 is limited in all directions by the second area 37 wetted with the diluent 39 by the second spray units 35. This ensures a well-defined spatial effect of the developer 38. The amount of fluid, the temperature, the pressure prior to the spray units 34, 35 and the concentration of the developer 38 are just some of the parameters that can be controlled to set a predetermined reaction dynamics of the developer 38 on the coating 33, as already mentioned above.

[0081] FIG. 4 shows another embodiment of the invention, again showing the optical element Mx, 117 in a plan view. In addition to the spray units 34, 35 already described in FIG. 3b, this device 30 comprises a drying unit embodied as an air knife 40. The air knife 40 is a linear air jet embodied to limit the extent of the respective fluids 38, 39 on the surface. This means that areas of the coating 33 can be protected from contact with the developer 38 and / or dilution fluid 39. Furthermore, the air knife 40 can also remove the fluids 38, 39 from the surface 32 in the direction of movement, by displacing them and forcing them forward. Possibly, furthermore, a suction unit 41 is arranged in front of the air knife 40 in the direction of movement of the air knife 40, which is represented in FIG. 4 by a dashed line. This unit sucks up the fluids 38, 39 consisting of developer 38 and dilution fluid 39 located on the surface 32, and an air knife 40 likewise pushes the fluids 38, 39 forward, as a result ensuring a dry surface outside the air knife 40. Furthermore, the device 30 comprises, by way of example, three sensors 42 arranged in front of the spray units 34, 35 in the direction of movement indicated by the arrows, for detecting the precise surface topography of the coating 33. The detection signals are transmitted via signal lines to actuators (not shown) of the device 30. The actuators determine the parameters of the spray units 34, 35 in order to ensure a uniform development speed over the entire surface 32.

[0082] As an alternative to the exemplary embodiment, the air knife 40 and suction unit 41 can also be positioned in the apparatus 30 to limit the first area 36 wetted with developer 38 to control the spatial effects of the developer 38 instead of dilution with additional fluid 39. [Explanation of symbols]

[0083] 1. Projection exposure equipment 2. Lighting system 3 Radiation source 4. Illumination optical unit 5 Object field of view 6 Object plane 7 Reticle 8 Reticle Holder 9 Reticle Displacement Drive 10 Projection optical unit 11 Image field 12 Image plane 13 Wafer 14 Wafer holder 15 Wafer Displacement Drive 16 EUV radiation 17 Collector 18 Intermediate focal plane 19 Deflection Mirror 20 Faceted Mirror 21 Facet 22 Faceted Mirror 23 Facet 30 equipment 31 Substrate 32 Surface 33 Coating 34 First spray unit 35 Second spray unit 36 First area 37 Second area 38 Reactive Fluids 39 Additional Fluids 40 Air Knife 41 Suction unit 42 Sensors 101 Projection exposure equipment 102 Lighting system 107 Reticle 108 Reticle Holder 110 Projection optical unit 113 Wafer 114 Wafer holder 116 DUV radiation 117 Optical Elements 118 Mount 119 Lens Housing M1~M6 Mirror

Claims

1. A method for chemically treating a surface (32) by application of a chemically reactive fluid (38), comprising the steps of: restricting said chemical treatment with said reactive fluid (38) to a predetermined area (36) by applying an additional fluid (39) to said area (36). The method includes:

2. 10. The method of claim 1 , A method wherein both fluids (38, 39) are liquids.

3. The method according to claim 1 or 2, The method, wherein said predetermined area (36) is restricted by neutralizing the action of said reactive fluid (38).

4. The method according to any one of claims 1 to 3, The method wherein said additional fluid (39) is embodied as a neutralizing fluid.

5. The method according to any one of claims 1 to 4, The method wherein the additional fluid (39) is embodied as a dilution fluid.

6. The method according to any one of claims 1 to 5, The method, wherein the predetermined area (36) is restricted by displacing the reactant fluid (38).

7. The method according to any one of claims 1 to 6, The method, wherein said additional fluid (39) is embodied as a displacement fluid.

8. 8. The method of claim 7, The method according to claim 1, wherein the displacement fluid (39) comprises dry air.

9. The method according to any one of claims 1 to 8, The method comprises at least one first spray unit (34) treating a first area (36) of said surface (32) with a reactive fluid (38) and at least one second spray unit (35) treating a second area (37) of said surface (32) with an additional fluid (39).

10. 10. The method of claim 9, The two regions (36, 37) are adjacent to each other.

11. 11. The method according to claim 9 or 10, The second region (37) partially surrounds the first region (36).

12. 11. The method according to claim 9 or 10, The second region (37) completely surrounds the first region (36).

13. The method according to any one of claims 9 to 12, The two regions (36, 37) overlap.

14. The method according to any one of claims 1 to 13, The method wherein the surface (32) is positioned on an optical element.

15. In any one of claims 1 to 14, The surface is spherical or aspherical and / or at least partially has a freeform surface.

16. The method according to any one of claims 1 to 15, The method, wherein said surface (32) is positioned on a substrate (31) of a component (Mx, 117) of a projection exposure apparatus (1, 101) for semiconductor lithography.

17. An apparatus (30) for chemically treating at least one surface (32) comprising a spray array having at least two spray units (34, 35) for applying at least one fluid (38, 39), comprising: The apparatus comprises a first spray unit (34) for treating a first area (36) of the surface (32) with a reactive fluid (38) and a second spray unit (35) for treating a second area (37) of the surface (32) with an additional fluid (39).

18. 18. The device (30) according to claim 17, The apparatus (30) comprises a drying unit (40).

19. 20. The device (30) according to claim 18, The drying unit is embodied as an air knife (40).

20. The device (30) according to any one of claims 17 to 19, The apparatus (30) comprises a suction unit (41).

21. A device (30) according to any one of claims 17 to 20, The apparatus (30) comprises at least one sensor (42) for detecting the topography of the surface (32).

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