Imaging EUV optical unit for imaging the object field into the image field.

Abstract

We provide an imaging EUV optical unit for imaging an object field into an image field. [Solution] The imaging EUV optical unit (10) plays the role of imaging the object field (5) onto the image field (11). Multiple mirrors (M1 to M8) play the role of guiding EUV imaging light (16) with a wavelength shorter than 30 nm along the imaging beam path from the object field (5) to the image field (11). The total transmittance of the multiple mirrors (M1 to M8) to the EUV imaging light (16) is greater than 5%. The image field (11) of the imaging optical unit (10) has a maximum extent of greater than 26 mm on the image plane (6). This results in an imaging EUV optical unit with improved usability for EUV projection exposure equipment.

Description

[Technical Field]

[0001] This patent application claims priority to German patent application DE102023203225.2, the contents of which are incorporated herein by reference.

[0002] The present invention relates to an imaging EUV optical unit for imaging an object field into an image field. Furthermore, the present invention relates to an optical system having such an imaging optical unit, a projection exposure apparatus having such an optical system, a method for manufacturing micro or nanostructure components using such a projection exposure apparatus, and micro or nanostructure components manufactured by the method. [Background technology]

[0003] The type of projection optical unit mentioned at the beginning is, WO2018 / 010960A1, DE102015209827A1, DE102012212753A1, U.S. Patent Application Publication No. 2010 / 0149509, It is known from U.S. Patent No. 4,964,706, DE102016218996A1, and DE102019202759A1. [Overview of the project]

[0004] The object of the present invention is to develop the imaging EUV optical unit of the type described at the beginning so that its usability in an EUV projection exposure apparatus is improved.

[0005] According to the present invention, this objective is achieved by an imaging EUV optical unit having the features specified in claim 1.

[0006] According to the present invention, it has been recognized that an imaging EUV optical unit can be designed to have both a high transmittance and a large maximum field of view spread compared to the prior art. For example, thereby, it becomes possible to simultaneously expose two exposed regions, that is, two exposure regions, which are positioned adjacent to each other in the maximum field of view spread direction, onto a substrate arranged in the field of view. As a result, the throughput of a projection exposure apparatus using this imaging EUV optical unit increases correspondingly. The maximum spread of the field of view in the image plane is given by the maximum spread of the field of view in the image plane where the field of view satisfies a specified imaging quality criterion.

[0007] The numerical aperture on the image side of the imaging EUV optical unit can be 0.5 or less. The numerical aperture on the image side can be less than 0.5, can be 0.4 or less, and for example, can be 0.33.

[0008] The total mirror surface, which corresponds to the sum of all the used mirror surfaces of a plurality of mirrors, that is, all the mirrors of the imaging EUV optical unit required to guide the imaging light, can be less than 1.5 m, 2 can be less than 1.25 m, 2 can be less than 1.0 m, 2 can be less than 0.8 m, 2 can be less than 0.76 m, 2 can be less than 0.75 m, 2 can be less than 0.71 m, 2 can be 0.7 m, 2 can be less than 0.69 m, 2 and can be.

[0009] The imaging EUV optical unit may include five or more mirrors for guiding EUV imaging light, may include seven or more mirrors for guiding EUV imaging light, or may include eight mirrors for guiding EUV imaging light.

[0010] For a given EUV light source power, an EUV total transmittance exceeding 5% enables an increased EUV throughput to the field of view, and thus, an improved exposure power. Alternatively, it is possible to use a reduced power source for a given required exposure power to the field of view.

[0011] The total transmittance of the imaging EUV optical unit may be greater than 10%, may be greater than 11%, may be greater than 12%, may be greater than 13%, may be greater than 14%, and may also be greater than 15%. Due to the number of mirrors and the individual EUV transmittances of the mirrors that typically guide the imaging light, which is 80% or less, the total transmittance is typically less than 20%.

[0012] When defining the total transmittance, all mirrors of the imaging EUV optical unit within the imaging beam path required for light guiding are considered.

[0013] The spread of the largest image field is preferably an integer multiple of the spread of the exposure area in the direction of the largest image field spread.

[0014] The anamorphic embodiment of the imaging optical unit according to claim 3 has been found to be advantageous, particularly for optimizing the illumination and light guiding of the imaging light within the region of the reflective object. An example of an anamorphic projection optical unit is disclosed in U.S. Patent No. 9,366,968.

[0015] The imaging scale ratio according to claim 4 has particularly proven its value. In particular, in that case, even for a large image field, it is possible to handle an object with a standard width on the object side. In absolute terms, the displacement direction imaging scale can be, for example, twice as large as the cross dimension imaging scale. In the case of comparison in absolute terms, the imaging scale is defined as a reduction ratio.

[0016] At least one intermediate image according to claim 5 allows the mirror surface of the mirror to be designed to be smaller in the region of the intermediate image.

[0017] In the embodiment according to claim 6, the imaging EUV optical unit does not have intermediate images perpendicular to the meridional plane. Image inversion occurs on the sagittal plane perpendicular to the meridional plane. Thus, there may be a choristikonal type imaging optical unit in the sense of U.S. Patent No. 10,656,400, in which there are a different number of intermediate images on imaging optical planes perpendicular to each other.

[0018] The arc-shaped region according to claim 7, which may be embodied as a ring region, enables an EUV optical unit with good image correction.

[0019] The double-arch image field according to claim 8 is well suited to the exposure symmetry of two exposure regions arranged side by side along the extent of the maximum image field. It is possible to provide a design for a double-arch region in which the extent of the region perpendicular to the direction of the maximum region extension is reduced compared to a simple arch that extends over the entire extent of this maximum region.

[0020] Providing the number of mirrors according to claims 9 and 10 has proven to be of practical value. It is possible to obtain a favorable combination of image field correction and transmission.

[0021] The GI mirrors directly continuous in the beam path according to claim 11 demonstrate value for guiding the imaging light. The imaging EUV optical unit may comprise two such pairs of GI mirrors. There may be addition or subtraction of the deflection effects of each GI mirror in one pair of GI mirrors.

[0022] The incidence angle sequence according to claim 12 has proven its value in practice.

[0023] If the imaging optical unit according to claim 13 has three or fewer GI mirrors, throughput advantages may arise. The throughput advantages may also arise if the imaging optical unit according to claim 13 has a total of seven or fewer mirrors.

[0024] The imaging optical unit may have exactly three GI mirrors. In this case, exactly two of these three GI mirrors may be designed as a directly consecutive mirror pair. Such a directly consecutive mirror pair of two GI mirrors can be designed so that the deflection effects of the two GI mirrors are added together, or so that the deflection effects of the two GI mirrors are subtracted.

[0025] The imaging optics unit may have exactly seven mirrors between the object field and the image field in the imaging beam path. In that case, the incident angle sequence could be: NI, GI, NI, GI, GI, NI, NI.

[0026] The advantages of the optical system according to claim 14, the projection exposure apparatus according to claim 15, the manufacturing method according to claim 16, and the microstructure or nanostructure component according to claim 17 correspond to the advantages already described above with respect to the projection optical unit according to the present invention.

[0027] The EUV light source of the projection exposure apparatus may be designed to produce usable wavelengths of 13.5 nm or less, less than 13.5 nm, less than 10 nm, less than 8 nm, less than 7 nm, for example, 6.7 nm or 6.9 nm. Usable wavelengths of less than 6.7 nm, especially on the order of 6 nm, are also possible.

[0028] In more detail, this projection lithography apparatus can be used to manufacture semiconductor components, such as memory chips.

[0029] Below, at least one exemplary embodiment of the present invention will be described with reference to the drawings. [Brief explanation of the drawing]

[0030] [Figure 1] This diagram schematically shows a meridian cross-section of a projection exposure apparatus for EUV projection lithography. [Figure 2]Figure 1 shows a meridian cross-section of an embodiment of an imaging optical unit used as a projection lens in a projection exposure apparatus, illustrating the imaging beam paths of the principal rays, upper coma rays, and lower coma rays of two selected field of view points. [Figure 3] This is a diagram of the imaging optical unit according to Figure 2, as viewed from viewing direction III in Figure 2. [Figure 4] This is a plan view of a wafer being exposed by a projection exposure apparatus, highlighting the individual exposure areas being scanned, which are rectangular in shape on the substrate being exposed. [Figure 5] Figure 4 is an enlarged plan view of detail V, which is rectangular in this case. It shows an example of the scanning path of the image field of the projection lens on the wafer, with the solid line representing the scanning path during projection exposure of the projection exposure apparatus, and the dashed line representing the scanning path when exposure is stopped. [Figure 6] Figure 5 shows an alternative configuration for the scanning path of the arch or ring region of the projection optical unit on the wafer section, similar to the diagram in Figure 5. [Figure 7] This figure shows the same wafer section and scanning path as in Figure 5, but using a rectangular image field with twice the width of the region perpendicular to the scanning direction compared to Figure 5. [Figure 8] For example, this figure shows a scanning path in a similar diagram to Figure 7 when using other alternative projection optical units, characterized by having an arch or ring region with twice the image field width perpendicular to the scanning direction compared to Figure 6. [Figure 9] As expected, the image field width is twice as wide as in Figure 6. In relation to this, Figure 7 shows the scanning path when using a double-arch image field of the projection optical unit, which is a further alternative form. The double-arch image field can be understood as two arch or ring regions from Figure 6 arranged side by side at right angles to the scanning direction. [Figure 10] Figure 2 and Figure 3 show a further embodiment of the imaging optical unit that can be used as a projection lens in the projection exposure apparatus shown in Figure 1. [Figure 11]Figure 2 and Figure 3 show a further embodiment of the imaging optical unit that can be used as a projection lens in the projection exposure apparatus shown in Figure 1. [Figure 12] Figure 2 and Figure 3 show a further embodiment of the imaging optical unit that can be used as a projection lens in the projection exposure apparatus shown in Figure 1. [Figure 13] Figure 2 and Figure 3 show a further embodiment of the imaging optical unit that can be used as a projection lens in the projection exposure apparatus shown in Figure 1. [Figure 14] Figure 2 and Figure 3 show a further embodiment of the imaging optical unit that can be used as a projection lens in the projection exposure apparatus shown in Figure 1. [Figure 15] Figure 2 and Figure 3 show a further embodiment of the imaging optical unit that can be used as a projection lens in the projection exposure apparatus shown in Figure 1. [Figure 16] Figure 2 and Figure 3 show a further embodiment of the imaging optical unit that can be used as a projection lens in the projection exposure apparatus shown in Figure 1. [Figure 17] Figure 2 and Figure 3 show a further embodiment of the imaging optical unit that can be used as a projection lens in the projection exposure apparatus shown in Figure 1. [Figure 18] Figure 2 and Figure 3 show a further embodiment of the imaging optical unit that can be used as a projection lens in the projection exposure apparatus shown in Figure 1. [Figure 19] Figure 2 and Figure 3 show a further embodiment of the imaging optical unit that can be used as a projection lens in the projection exposure apparatus shown in Figure 1. [Modes for carrying out the invention]

[0031] In the following description, the basic components of the microlithograph projection exposure apparatus 1 are first explained as an example with reference to Figure 1. The description of the basic structure of the projection exposure apparatus 1 and its components should not be interpreted as restrictive.

[0032] One embodiment of the illumination system 2 of the projection exposure apparatus 1 includes, in addition to a light source or radiation source 3, an illumination optical unit 4 for illuminating the object field 5 within the object surface 6. In an alternative embodiment, the light source 3 may be provided as a module separate from the rest of the illumination system. In that case, the illumination system does not include the light source 3.

[0033] A reticle 7 positioned in the object field 5 is exposed. The reticle 7 is held by a reticle holder 8. The reticle holder 8 is displaceable, particularly in the scanning direction, by a reticle displacement drive mechanism 9.

[0034] The projection exposure apparatus 1 includes a projection optical unit or an imaging optical unit 10. The projection optical unit 10 plays the role of imaging the object field 5 onto the image field 11 of the image plane 12. The image plane 12 extends parallel to the object field 6. Alternatively, an angle other than 0° between the object field 6 and the image plane 12 is also possible.

[0035] For explanatory purposes, the Cartesian xyz coordinate system is shown in Figure 1. The x-direction extends perpendicular to the plane of the drawing and toward the back of the drawing. The y-direction extends horizontally, and the z-direction extends vertically. In Figure 1, the scanning direction extends in the y-direction. The z-direction extends perpendicular to the image plane 12.

[0036] The structure on the reticle 7 is imaged onto the photosensitive layer of the wafer 13, which is positioned in the image field 11 region of the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 is displaceable, particularly in the y-direction, by a wafer displacement drive mechanism 15. Firstly, the displacement of the reticle 7 by the reticle displacement drive mechanism 9 and secondly, the displacement of the wafer 13 by the wafer displacement drive mechanism 15 can be performed in synchronization with each other.

[0037] Radiation source 3 is an EUV radiation source. Radiation source 3 emits EUV radiation 16 in particular, which will be referred to below as the radiation used or illumination radiation. Specifically, the radiation used has a wavelength in the range of 5 nm to 30 nm. Radiation source 3 may be a plasma source, such as an LPP (laser-generated plasma) source or a GDPP (gas discharge-generated plasma) source. It may also be a synchrotron-based radiation source. Radiation source 3 may be a free electron laser (FEL).

[0038] Illumination radiation 16 emitted from radiation source 3 is focused by a focuser 17. The focuser 17 may have one or more ellipsoidal and / or hyperbolic reflective surfaces. Illumination radiation 16 can be incident on at least one reflective surface of the focuser 17 by grazing incidence (GI), i.e., at an incidence angle greater than 45°, or by normal incidence (NI), i.e., at an incidence angle less than 45°. The focuser 17 may be structured and / or coated to optimize its reflectivity to the radiation used, on the one hand, and to suppress stray light, on the other hand.

[0039] The illumination radiation 16 propagates downstream of the concentrator 17, through the intermediate focal point of the intermediate focal plane 18. The intermediate focal plane 18 can correspond to the boundary between the radiation source module, which includes the radiation source 3 and the concentrator 17, and the illumination optical unit 4.

[0040] The illumination optical unit 4 includes a first facet mirror 19. When the first facet mirror 19 is positioned on a surface of the illumination optical unit 4 that is optically conjugate to the object surface 6, this facet mirror is also called a field-of-view facet mirror. The first facet mirror 19 comprises a number of individual first facets 20, which are hereinafter also referred to as field-of-view facets. Only a few of these facets are illustrated illustratively in Figure 1.

[0041] The first facet 20 may be embodied as a macroscopic facet, particularly as a rectangular facet, or as a facet having an arched edge contour or a partial circular edge contour. The first facet 20 may be embodied as a planar facet, or alternatively as a facet having a convex or concave curvature.

[0042] For example, as known from DE102008009600A1, the first facet 20 itself may, in each case, consist of a number of individual mirrors, in particular a number of micromirrors. The first facet mirror 19 may be formed in particular as a micro-electromechanical system (MEMS system). For further details, see DE102008009600A1.

[0043] The deflection mirror US is located between the intermediate focal point of the intermediate focal plane 18 in the beam path of the illumination optical unit 4 and the first facet mirror 19. This deflection mirror US may be implemented as a planar mirror, but may also have a beam shaping effect. In particular, depending on the arrangement of the light source 3, it may be possible to omit the deflection mirror US.

[0044] Within the beam path of the illumination optical unit 4, the second facet mirror 21 is positioned downstream of the first facet mirror 19. When the second facet mirror 21 is positioned on the pupil plane EP of the illumination optical unit 4, it is also called a pupil facet mirror. The second facet mirror 21 may be positioned at a distance from the pupil plane of the illumination optical unit 4. In that case, the combination of the first facet mirror 19 and the second facet mirror 21 is also called a specular reflector. Specular reflectors are known from U.S. Patent Application Publication No. 2006 / 0132747, EP1614008B1 and U.S. Patent No. 6,573,978.

[0045] The second facet mirror 21 comprises multiple second facets 22. In the case of a pupil facet mirror, the second facets 22 are also called pupil facets.

[0046] The second facet 22 may also be a macroscopic facet, which may have, for example, a circular, rectangular, or hexagonal boundary, or alternatively, a facet composed of micromirrors. In this regard, DE102008009600A1 is similarly referenced.

[0047] The second facet 22 may have a planar reflective surface, or alternatively, a curved reflective surface that is convex or concave.

[0048] As a result, the illumination optical unit 4 forms a dual-faceted system. This basic principle is also known as a fly's eye integrator.

[0049] In some cases, it may be advantageous not to position the second facet mirror 21 precisely on a plane that is optically conjugate to the pupil plane of the projection optical unit 10. More specifically, the pupil facet mirror 21 may be positioned at an angle to the pupil plane of the projection optical unit 10, as described, for example, in DE102017220586A1.

[0050] Each first facet 20 is imaged onto the object field 5 using a second facet mirror 21, and optionally using an imaging optical assembly in the form of a transmission optical unit, which is not shown in Figure 1.

[0051] The transmission optics unit may have exactly one mirror, or alternatively, two or more mirrors, which are arranged in a row within the beam path of the illumination optics unit 4. The transmission optics unit may, in particular, comprise one or two direct incidence mirrors (NI mirrors) and / or one or two oblique incidence mirrors (GI mirrors). In the embodiment shown in Figure 1, the illumination optics unit 4 has exactly three mirrors, namely, downstream of the concentrator 17, a deflection mirror US, a first faceted mirror 19, and a second faceted mirror 21.

[0052] The second facet mirror 21 is either the last beam-shaping mirror or the actual last mirror for the illumination radiation 16 in the beam path upstream of the object field 5, to the extent that no further transmission optics units downstream of the second facet mirror 21 are required. An example of an illumination optics unit 4 without a transmission optics unit is disclosed in Figure 2 of WO2019 / 096654A1.

[0053] The imaging of the first facet 20 onto the object surface 6 using the second facet 22, or using the second facet 22 and the transmission optics unit, is mostly only an approximate image.

[0054] The projection optical unit 10 is equipped with multiple mirrors, namely eight mirrors M1 to M8 (see Figure 2), which are numbered sequentially according to their order within the beam path of the projection exposure apparatus 1.

[0055] In the example shown in Figure 2, the projection optics unit 10 comprises eight mirrors M1 to M8. Alternative examples with four, five, six, or other numbers of mirrors Mi are equally possible.

[0056] The projection optics unit 10 is a non-obscured optics unit. None of the mirrors M1 to M8 contain a through aperture for the illumination radiation 16.

[0057] The projection optical unit 10 has an image-side numerical aperture of 0.33. Depending on the embodiment of the projection optical unit 10, the image-side numerical aperture may be in the range of, for example, 0.25 to 0.4. Depending on the embodiment, the image-side numerical aperture of the projection optical unit 10 may also be a different value.

[0058] The reflective surface of mirror Mi is realized as a free-form surface without a rotational symmetry axis. Alternatively, the reflective surface of mirror Mi may be designed as an aspherical surface having exactly one rotational symmetry axis of the reflective surface shape. Similar to the mirrors of illumination optical unit 4, mirror Mi may have a high-reflectivity coating for illumination radiation 16. These coatings may be designed as multilayer coatings having, for example, alternating layers of molybdenum and silicon. Ruthenium coatings are also possible, particularly for grazing incidence mirrors (GI mirrors).

[0059] The projection optics unit 10 provides a size reduction of 2:1 in the x-direction, i.e., perpendicular to the scanning direction y. The imaging scale β in the x-direction x This imaging scale β is -2.00. x This is also called the cross-dimensional imaging scale.

[0060] In the scanning direction y, the projection optical unit 10 results in a 4:1 size reduction, but in this case, image inversion does not occur (β y = +4.00). This imaging scale β y This is also called the displacement direction imaging scale.

[0061] The imaging scale described here is the reduction ratio of the projection optical unit 10 when imaging the object field 5 onto the image field 11.

[0062] Therefore, the projection optical unit 10 has a displacement-direction imaging scale in the scanning direction y on the imaging optical plane yz, which is, in absolute value, twice the size of the cross-dimensional imaging scale present in the cross-scanning direction x on another imaging on the optical plane xz perpendicular to the scanning direction y, i.e., the object displacement direction. This ratio of the displacement-direction imaging scale to the cross-dimensional imaging scale can be in the range of 1.1 to 5, and for example, it can be 2.

[0063] The projection optics unit 10 has an anamorphic design. It has different imaging scales β in the x and y directions. x , β yIt has two imaging scales β of the projection optical unit 10. x , β y Preferably (β x ,β y ) = (+ / -2, / + / -4 or + / -8), in particular (β x ,β y ) = (+ / -2, + / -4) or (+ / -4, + / -8).

[0064] Other imaging scales are also possible. Imaging scales with the same sign in the x and y directions are also possible.

[0065] When an anamorphic projection optics unit is used, it is possible to achieve a smaller principal ray angle of the illumination beam at reticle 7 while avoiding undesirable shading effects.

[0066] The projection optics unit 10 has an isomorphic configuration, meaning that the imaging scale β has the same absolute value in the x and y directions. x , β y It can also have.

[0067] The image field 11 of the projection optical unit 10 is rectangular and has an x-direction width of 52 mm and a y-direction width of 1.8 mm. Therefore, perpendicular to the scanning direction y of the projection exposure apparatus 1 designed as a scanner, the image field has an area width that is twice the y-direction width of a typical exposure area 23 being scanned.

[0068] This will be explained in detail below, based on Figures 4 to 7, and especially on Figures 4 and 7.

[0069] Figure 4 shows a plan view of a wafer 13 having rectangular exposure regions 23, which are arranged on the wafer in a raster manner and scanned relative to the image field 11. Each exposure region 23 has a typical extent of 26 mm in the x-direction and a typical extent of 32 mm in the y-direction. The wafer 13 has a standard diameter of 300 mm.

[0070] Figure 5 shows an exemplary scanning path S on a section of wafer 13 when using an image field 11 of a modified projection optics unit 10 having a standard image field width of 26 mm in the x-direction, corresponding to the x-direction spread of the exposure area 23. In Figure 5, solid lines are used to represent the portion of the scanning path S of the image field 11 on the wafer 13 in which projection exposure is performed by the projection exposure apparatus 1. While these scanning path portions extend linearly in the y-direction, i.e., the scanning direction, the image field 11 is scanned across the entirety of each exposure area 23, resulting in the exposure of the entire exposure area 23.

[0071] Figure 5 shows, as an example, a scanning path S for exposing exactly one row of adjacent exposure regions 23 onto the wafer 13. As the exposure portion of the scanning path S, i.e., the portion of the scanning path S drawn as a solid line and extending straight along the y-direction, becomes correspondingly longer, it becomes possible to expose multiple rows of adjacent exposure regions 23 in the y-direction onto the wafer 13.

[0072] The dashed lines in Figure 5 represent the connection points of the scanning path S that connect adjacent exposed areas in each case; that is, these lines represent the portion of the relative movement of the image field 11 with respect to the wafer 13 in which the wafer 13 is not exposed. In the example shown in the figure, each connection point has the shape of a 180° arch.

[0073] In principle, the relative movement of the image field 11 with respect to the wafer 13 is generated by the displacement of the wafer 13 relative to the projection optical unit 10 by an actuator in the y-direction or x-direction.

[0074] In the embodiment shown in Figure 5, where the width of the image field is the same as the width of the exposure area (26 mm), exactly one exposure area 23, or one column portion in which exposure areas 23 are adjacent to each other within a single column, is exposed in each scanning step of the projection exposure apparatus 1.

[0075] Figure 6 shows a scanning path S corresponding to Figure 5 when using a modified projection optical unit 10 having an arc-shaped or ring-shaped image field 11, where the image field also has a standard width of 26 mm in the x-direction, i.e., a width that precisely corresponds to the width of the exposure area 23. Therefore, the description above for the situation in Figure 5 also applies here.

[0076] Figure 7 shows the scanning path S when using the image field 11 of the projection optical unit 10 according to Figure 2, i.e., a rectangular image field 11 with an x-width extension corresponding to twice the x-width of each exposure area 23. Using this twice-width image field 11 of the projection optical unit 10 according to Figure 2, two adjacent exposure areas 23 in the x-direction are scanned and exposed simultaneously along each exposure portion of the scanning path S. Therefore, in each scanning step, a projection exposure apparatus with the projection optical unit 10 according to Figure 2, in which the image field 11 is twice the width, has twice the exposure throughput of the exposure areas 23 to be exposed compared to the projection optical unit with a single-width image field 11 according to Figures 5 and 6. In detail, the number of unproductive connection points (dashed lines) can be approximately halved in relation to the exposure areas 23 exposed in each exposure portion.

[0077] As an alternative to the rectangular image field 11 with twice the width, it is also possible to use an arched or partial ring-shaped image field 11 with twice the width, as shown in Figure 8. Such arched or partial ring-shaped image fields 11 appear in variations of the projection optical unit 10.

[0078] As a further alternative to the double-width rectangular image field 11, a double-arch image field 11 can also be used, as shown in Figure 9. Such a double-arch image field 11 according to Figure 9 can be understood as two single-width arched or partially ring-shaped image fields 11, as shown in Figure 6, arranged side by side in the x-direction. Such a double-arch image field 11 according to Figure 9 appears in further modifications of the projection optical unit 10.

[0079] In each case, to form an illumination channel that illuminates the object field 5, one of the pupil facets 22 is assigned to exactly one of the field of view facets 20. In detail, this can produce illumination according to Köhler's principle. The far field of view is decomposed into multiple object fields 5 using the field of view facets 20. Each of the field of view facets 20 generates multiple intermediate focal images in the pupil facets 22 assigned to it.

[0080] The assigned pupil facets 22 cause the field of view facets 20 to be imaged onto the reticle 7 in each case so as to superimpose on each other for the purpose of illuminating the object field 5. The illumination of the object field 5 is particularly uniform as possible, preferably with a uniformity error of less than 2%. Field of view uniformity may be achieved by superimposing different illumination channels.

[0081] The illumination of the entrance pupil of the projection optical unit 10 can be geometrically defined by the arrangement of the pupil facets 22 used. The intensity distribution of the entrance pupil of the projection optical unit 10 can be set by selecting the illumination channels, particularly the subset of pupil facets that guide the light. This intensity distribution is also referred to as the illumination setting or illumination pupil filling.

[0082] The uniformity of the pupil, which is illuminated as defined, in multiple regions of the illumination pupil of the illumination optical unit 4, can be achieved by redistributing the illumination channels.

[0083] The projection optical unit 10 is telecentric on the image side.

[0084] Further aspects and details of the illumination of the object field 5, particularly the entrance pupil of the projection optical unit 10, are described below.

[0085] The projection optics unit 10 may have a concentric entrance pupil. In this case, the pupil facet mirror 21 can be positioned in the region of the entrance pupil of the projection optics unit 10, and then in the beam path upstream of the object field 5. In an alternative example, the projection optics unit 10 may also have a telecentric embodiment on the object side. If the entrance pupil of the projection optics unit 10 is unreachable, the positioning surface of the pupil facet mirror 21 can be imaged onto the entrance pupil using other components of the illumination optics unit 4.

[0086] The entrance pupil of the projection optical unit 10 cannot typically be precisely illuminated using the pupil facet mirror 21. When the projection optical unit 10 images the center of the pupil facet mirror 21 telecentrically onto the wafer 13, the aperture rays often do not intersect at a single point. However, it is possible to find an area where the distance between the paired aperture rays is minimized. This area corresponds to the entrance pupil or its conjugate area in real space. More specifically, this area has a finite curvature.

[0087] The projection optics unit 10 may have entrance pupils with different orientations for the tangential beam path and the sagittal beam path. In this case, the imaging element, particularly the optical component of the transmission optics unit, must be provided between the second facet mirror 21 and the reticle 7. This optical element can be used to take into account the different orientations of the entrance pupil in the tangential and sagittal directions.

[0088] In the arrangement of the components of the illumination optical unit 4 shown in Figure 1, the pupil facet mirror 21 is positioned at an angle with respect to the object surface 5. The second facet mirror 21 is further positioned at an angle with respect to the arrangement plane defined by the first facet mirror 19.

[0089] Further details regarding the projection optical unit 10 are described later in this specification based on Figures 2 and 3.

[0090] The projection optics unit 10 has four NI mirrors (direct incidence mirrors), namely M1, M4, M7, and M8 in the imaging beam path of the projection optics unit 10. The imaging light 16 is irradiated onto these NI mirrors M1, M4, M7, and M8 at an incidence angle of less than 45°. The maximum incidence angle of the imaging light 16 incident on each NI mirror may be less than 40°, less than 35°, less than 30°, less than 25°, less than 20°, less than 15°, and less than 10°.

[0091] The other mirrors M2, M3, M5, and M6 of the projection optics unit 10 are GI mirrors (mirrors for oblique incidence). These mirrors M2, M3, M5, and M6 have incidence angles of illumination light 16 to the mirror greater than 45° in each case. The minimum incidence angle incident to each GI mirror may be greater than 50°, greater than 55°, greater than 60°, greater than 65°, greater than 70°, greater than 75°, and greater than 80°.

[0092] Information regarding reflection in GI mirrors (oblique incidence mirrors) can be found in WO2012 / 126867A. Further information regarding the reflectivity of NI mirrors (direct incidence mirrors) can be found in DE10155711A.

[0093] Depending on the embodiment of the projection optics unit 10, there may be five or more NI mirrors and / or three or fewer or five or more GI mirrors.

[0094] The deflection effects of mirrors M2 and M3 on one side are added together with the deflection effects of M5 and M6 on the other side. Thus, the projection optical unit 10 shown in Figure 2 has two pairs of GI mirrors, and the deflection effects of these GI mirrors are added together in each case.

[0095] The four NI mirrors M1, M4, M7, and M8 each have a subtractive deflection effect on one another, and as a result, the imaging beam path is guided through these four NI mirrors M1, M4, M7, and M8 along a zigzag path between the object field 5 and the image field 11.

[0096] None of the mirrors M1 to M8 have through apertures, and in each case, the mirrors are used in a reflective manner within a continuous region without gaps.

[0097] Figure 2 shows the calculated reflective surfaces of mirrors M1 to M8. The reflective surfaces of mirrors M1 to M8 are supported by the mirror body (not shown) in a known manner. Without considering the polishing overrun edge, the projection optical unit 10 is 0.71 m 2 It has a total mirror surface.

[0098] The object plane 6 and the image plane 12 extend parallel to each other with good approximation.

[0099] The reflective surface of the third-to-last mirror M6 in the imaging beam path faces the last mirror M8. As a result, the imaging beam path is guided around the last mirror M8. Between mirrors M4 and M7, the imaging beam path of the imaging light 16 is guided around mirror M8 by the two GI mirrors M5 and M6.

[0100] The number of intermediate image planes in the x-direction and the number of intermediate image planes in the y-direction within the beam path between the object field 5 and the image field 11 differs in the case of the projection optical unit 10. In the yz plane, the projection optical unit 10 has an intermediate image ZB in the form of a caustic, which is located in the region of the intermediate image placement plane 24 between mirrors M5 and M6 in the imaging beam path, as shown by the meridional cross section in Figure 2. The intermediate image ZB is located in the meridional plane of the projection optical unit 10, that is, in the plane containing the principal ray of the central field of view point of the projection optical unit 10.

[0101] Imaging scale β xWhen the value is -2.00, the projection optical unit 10 does not have an intermediate image in the imaging direction perpendicular to it, as can be inferred from the diagram in Figure 3. The image plane 12 is the first field of view after the object plane 6 in the xz principal plane of the projection optical unit 10 which is perpendicular to the meridional plane, that is, in the imaging beam path of the projection optical unit 10 which is perpendicular to the yz meridional plane. Therefore, the projection optical unit 10 does not have an intermediate image perpendicular to the meridional plane. Thus, there is an image inversion perpendicular to the meridional plane.

[0102] An example of a projection optical unit in which the number of such intermediate images differs in the x and y directions, or in imaging planes perpendicular to each other, is known from U.S. Patent Application Publication No. 2018 / 10656400. Alternatively, the projection optical unit 10 may also be designed to have no intermediate images, or to have the same number of intermediate images in the x and y directions.

[0103] The object field 5 and the image field 11 are at a distance d OIS The objects are offset from each other in the y-direction by (object-image offset d). OIS The object-image offset d is measured between the central field of view point of object field 5 and the central field of view point of image field 11, such that it is perpendicular to the perpendicular N of the image plane 12. OIS It is 910mm.

[0104] The total transmittance of the projection optical unit 10, which is expressed as the product of the EUV reflectances of each mirror M1 to M8 with respect to the illumination light 16 along the imaging beam path passing through the projection optical unit 10, is 10.2% in the projection optical unit 10 shown in Figure 2. Therefore, on average, each of the mirrors M1 to M8 has a reflectance of more than 75%.

[0105] Therefore, the total transmittance of mirrors M1 to M8, i.e., the total transmittance of the projection optical unit 10, is greater than 5%. The total transmittance of the projection optical unit 10 may be greater than 6%, greater than 7%, greater than 8%, greater than 9%, and also greater than 10%. Due to the number of mirrors and the individual EUV transmittance of the mirrors that guide the imaging light, which is usually 80% or less, the total transmittance is usually less than 15%.

[0106] In the yz plane, the first pupil of the projection optics unit 10 is located in the region of reflection of the imaging light 16 at mirror M2 in the beam path of the imaging light. The second pupil in the yz plane is located in the same place as the pupil in the xz plane, which is perpendicular to the yz plane, between mirrors M7 and M8 in the imaging beam path. In the case of the projection optics unit 10, the aperture can be restricted by an aperture diaphragm, which may restrict the imaging beam path, particularly at the edge, and may be mounted between mirrors M7 and M8. If necessary, an internal obscuration may be defined by this diaphragm using appropriate diaphragm portions. In the case of the projection optics unit 10, the aperture diaphragm exists in the form of multiple diaphragm portions arranged separately from one another. For example, such a concept using multiple diaphragm portions is known from U.S. Patent No. 10,527,832. In the case of the projection optics unit 10, these diaphragm portions are partially located between mirrors M7 and M8 and at the location of mirror M7 in the beam path of the illumination light 16.

[0107] The distance between the object plane 6 and the image plane 12 is 1708 mm in the case of the projection optical unit 10.

[0108] Mirrors M1-M8 are coated to optimize their reflectivity to the imaging light 16. In particular, for GI mirrors, this may be a lanthanum coating, a boron coating, a boron coating with a lanthanum top layer, or a ruthenium coating. Other coating materials, especially lanthanum nitride and / or B4C, may also be used. For oblique incidence mirrors M2, M3, M5, and M6, a coating containing, for example, one layer of boron or lanthanum can be used. In particular, the high-reflectivity layers of mirrors M1, M4, M7, and M8 for direct incidence can be constructed as multilayers, and consecutive layers may be made from different materials. Alternating material layers are also usable. A typical multilayer can have 50 double layers, each made from a boron layer and a lanthanum layer. Layers containing lanthanum nitride and / or boron, especially B4C, may also be used.

[0109] Table 1 below summarizes the parameters of the projection optics unit 10. In addition to the data already described above, Table 1 also specifies the angle of the principal ray of the central field point relative to the z axis, as well as the usable etendue and mean wavefront aberration RMS values ​​of the projection optics unit.

[0110] [Table 1]

[0111] The z-direction extent of the installation space cube represents the maximum z-direction distance between the optical surfaces used, i.e., in the example of the projection optical unit 10, the maximum z-direction distance between the optical surface portion of mirror M4 and the optical surface portion of mirror M7.

[0112] Tables 2a and 2b below summarize the parameters of the mirrors M1 to M8 of the projection optical unit 10: "maximum incident angle," "spread of the reflective surface in the x-direction," "spread of the reflective surface in the y-direction," and "maximum mirror diameter."

[0113] [Table 2]

[0114] [Table 3]

[0115] The mirror surfaces of the illustrated mirrors M1 to M8 do not have polished overrun edges. The actual working mirror surfaces of mirrors M1 to M8 include the reflective surface actually used to reflect the imaging light 16, and a polished overrun edge with a radius of approximately 20 mm. Therefore, a protrusion in the form of a polished overrun edge of at least 10 mm, generally 20 mm, exists between the reflective mirror surface and the area of ​​the mirror surface that has not been polished further.

[0116] The total mirror surface area, which corresponds to the sum of the actual reflective mirror surfaces used for mirrors M1 to M8, excluding polished overrun edges, is 1.5 m 2 It is less than . The polished overrun edge is included in this total mirror surface. This total mirror surface is 0.71 m in the projection optical unit 10 as shown in Figure 2. 2 Therefore, taking into account the polishing overrun edge, the total mirror surface is 0.92 m². 2 That is the case.

[0117] Mirrors M1-M8 are realized as free surfaces that cannot be described by rotational symmetry functions. Other embodiments of the projection optical unit 10 are also possible in which at least one of mirrors M1-M6 is realized as a rotationally symmetric aspherical surface. It is also possible that all of the mirrors M1-M6 are realized as such aspherical surfaces.

[0118] A free surface can be described by the following free surface equation (Equation 1).

number

[0119] The following applies to the parameters of equation (1).

[0120] Z is the sagittal height of the freeform surface at point x,y, and x 2 +y 2 =r 2 Here, r is the distance from the reference axis (x=0; y=0) of the free surface equation.

[0121] In equation (1) for the free surface, C1, C2, C3... represent the coefficients of the free surface series expansion as powers of x and y.

[0122] In the case of a cone-shaped base region, c x , c y c is a constant corresponding to the vertex curvature of the corresponding aspherical surface. Therefore, c x = 1 / R x (1 / RDX) and c y = 1 / R y (1 / RDY) is the relevant value. x and k y (CCX,CCY) correspond to the cone constants of the corresponding aspherical surfaces. Therefore, equation (1) describes a free surface of a biconical shape.

[0123] Alternative freeform surfaces can be generated from rotationally symmetric reference surfaces. Such freeform surfaces for the reflective surfaces of mirrors in the projection optics unit of a microlithography projection exposure apparatus are known from U.S. Patent Application Publication No. 20070058269.

[0124] Alternatively, freeform surfaces can also be described using two-dimensional spline surfaces. Examples include Bézier curves or non-uniform rational basis splines (NURBS). For example, a two-dimensional spline surface can be described by a grid of points on the xy plane and their associated z values, or by these points and their associated gradients. Depending on the type of spline surface, the completed surface can be obtained by interpolation between grid points, for example, using polynomials or functions that have specific properties with respect to their continuity and differentiability. An example of this is an analytical function.

[0125] The optical design data for the reflective surfaces of mirrors M1 to M8 of the projection optical unit 10 can be obtained from the other tables below.

[0126] Table 3 specifies the coordinates of the surface origin of each mirror surface and one area of ​​the object field 5 with respect to the xyz coordinate system of the image field 11.

[0127] The first column specifies the distance of each mirror or object field 5 from the coordinate origin at the center of the image field 11 in the x-direction (first column), y-direction (second column), and z-direction (third column).

[0128] The other columns in Table 3 (Table 3b) further specify the inclination values ​​of the respective surfaces or object fields 5 of mirrors M1 to M8 with respect to the x, y, and z axes. In the embodiment shown in Figure 2, both the object field 5 and the image field 11 are not inclined with respect to the x-axis and extend parallel to each other.

[0129] Table 4 shows, for each mirror M1 to M8, the parameters RDX, RDY, CCX, CCY, and the values ​​of the coefficients C1, C2, C3... of the series expansion of the free surface according to equation (1) above, arranged according to the powers of x and y.

[0130] Table 5 shows the reflectance of mirrors M1 to M8 and the total transmittance of the projection optical unit 10, which is 10.2%.

[0131] [Table 4]

[0132] [Table 5]

[0133] [Table 6] TIFF2026511986000009.tif211153 TIFF2026511986000010.tif212153 TIFF2026511986000011.tif211153 TIFF2026511986000012.tif212153 TIFF2026511986000013.tif211153 TIFF2026511986000014.tif212153 TIFF2026511986000015.tif211153 TIFF2026511986000016.tif212153 TIFF2026511986000017.tif211153 TIFF2026511986000018.tif212153 TIFF2026511986000019.tif211153 TIFF2026511986000020.tif212153 TIFF2026511986000021.tif211153 TIFF2026511986000022.tif212153 TIFF2026511986000023.tif217153

[0134] [Table 7]

[0135] A Miller with values ​​RDX and RDY having different signs is a saddle point type or minimax basic shape.

[0136] In the case of the projection optical unit 10, the GI mirror M6 is spatially located next to the last mirror M8.

[0137] Figures 10 and 11 show further embodiments of the projection optical unit or imaging optical unit 27, which may be used in the projection exposure apparatus 1 instead of the projection optical unit 10 in the embodiment according to Figure 2. With respect to Figures 1 to 9, and in particular with respect to Figures 1 to 3, components and functions corresponding to those already described above are indicated by the same reference numerals and a detailed description is omitted.

[0138] The basic structure of the projection optical unit 27 corresponds to the basic structure of the projection optical unit 10.

[0139] In the case of the projection optical unit 27, the two GI mirrors M2 and M3 on one side and M5 and M6 on the other side each have a subtractive deflection effect on each other in each case.

[0140] The final GI mirror M6 is spatially adjacent to the final mirror M8 and determines the image-side numerical aperture of the projection optical unit 27.

[0141] In the projection optics unit 27, the intermediate image ZB, which is in the form of a fire surface, is located between mirrors M4 and M5 in the imaging beam path.

[0142] The projection optics unit 27 has an entrance pupil that can reach into the imaging beam path upstream of the object field 5.

[0143] In the projection optical unit 27, the exit pupil is located in the reflection region of the mirror M7. The aperture diaphragm can be placed on this mirror, and if necessary, the internal obscuration of the projection optical unit 27 can be defined.

[0144] The distance between the object plane 6 and the image plane 12 is 1650 mm in the case of the projection optical unit 27.

[0145] The total transmittance of the projection optical unit 27 is 10.4%.

[0146] The following tables summarize the parameters and optical design of the projection optics unit 27. Regarding its structure, these tables correspond to those already described above with respect to Figure 2.

[0147] Table 6 shows the aperture diaphragm AS data of the projection optical unit 27 positioned in the region of mirror M7. This aperture is defined by a polygon, and its x and y values ​​are specified in Table 6.

[0148] [Table 8]

[0149] [Table 9]

[0150] [Table 10]

[0151] [Table 11]

[0152] The aperture AS is positioned on the mirror M7. The position and inclination of the aperture surface of the aperture AS take into account the recession of the mirror M7 at the edge of its opening.

[0153] [Table 12]

[0154] [Table 13] TIFF2026511986000031.tif211153 TIFF2026511986000032.tif212153 TIFF2026511986000033.tif211153 TIFF2026511986000034.tif212153 TIFF2026511986000035.tif211153 TIFF2026511986000036.tif212153 TIFF2026511986000037.tif211153 TIFF2026511986000038.tif212153 TIFF2026511986000039.tif211153 TIFF2026511986000040.tif212153 TIFF2026511986000041.tif211153 TIFF2026511986000042.tif212153 TIFF2026511986000043.tif211153 TIFF2026511986000044.tif212153 TIFF2026511986000045.tif217153

[0155] Table 14

[0156] Table 15

[0157] If polishing overrun edges are not taken into consideration here, the projection optical unit 27 will be 0.76m 2 It has a total mirror surface. Taking into account the polished overrun edge, the total mirror surface is 0.97 m 2 That is the case.

[0158] Figures 12 and 13 show further embodiments of the projection optical unit or imaging optical unit 28, which may be used in the projection exposure apparatus 1 instead of the projection optical unit 10 in the embodiment according to Figure 2. With respect to Figures 1 to 11, and in particular with respect to Figures 1 to 3, components and functions corresponding to those already described above are indicated by the same reference numerals and a detailed description is omitted.

[0159] Regarding the basic structure, the projection optical unit 28 shown in Figures 12 and 13 is similar to the projection optical unit 27 shown in Figure 10. The essential difference is that, as can be inferred from the diagram in Figure 13, the projection optical unit 28 also has an intermediate image on a plane perpendicular to the meridional plane. The intermediate image ZB is located between mirrors M4 and M5 in the imaging beam path, and both of these mirrors are on the meridional plane and the plane perpendicular to it, as shown in Figure 12.

[0160] The projection optics unit 28 is telecentric on the object side. Here again, the exit pupil is located in the region of reflection of the imaging beam path, near mirror M7. An aperture diaphragm and optionally an obscuration diaphragm can also be attached there, and between mirrors M7 and M8 in the imaging beam path, here again, in several places. Thus, what was described above in relation to the projection optics unit 10 applies here.

[0161] The distance between the object plane 6 and the image plane 12 is 2151 mm in the case of the projection optical unit 28.

[0162] The following tables summarize the parameters and optical design of the projection optics unit 28. Regarding its structure, these tables correspond to those already described above with respect to Figure 2.

[0163] [Table 16]

[0164] [Table 17]

[0165] [Table 18]

[0166] [Table 19]

[0167] [Table 20]

[0168] [Table 21] TIFF2026511986000054.tif211153 TIFF2026511986000055.tif212153 TIFF2026511986000056.tif211153 TIFF2026511986000057.tif212153 TIFF2026511986000058.tif211153 TIFF2026511986000059.tif212153 TIFF2026511986000060.tif211153 TIFF2026511986000061.tif212153 TIFF2026511986000062.tif211153 TIFF2026511986000063.tif212153 TIFF2026511986000064.tif211153 TIFF2026511986000065.tif212153 TIFF2026511986000066.tif211153 TIFF2026511986000067.tif212153 TIFF2026511986000068.tif217153

[0169] [Table 22]

[0170] Excluding the polished overrun edge, the projection optics unit 28 measures 0.69 m. 2 It has a total mirror surface.

[0171] Figures 14 and 15 show further embodiments of the projection optical unit or imaging optical unit 29, which may be used in the projection exposure apparatus 1 instead of the projection optical unit 10 in the embodiment according to Figure 2. With respect to Figures 1 to 13, and in particular with respect to Figures 1 to 3, components and functions corresponding to those already described above are indicated by the same reference numerals and a detailed description is omitted.

[0172] In terms of basic structure, the projection optical unit 29 shown in Figures 14 and 15 is similar to the projection optical unit 10 shown in Figures 2 and 3. The essential difference is that instead of two consecutively arranged GI mirrors M2 and M3, the projection optical unit 29 has exactly one GI mirror, namely mirror M2. In principle, this GI mirror M2 of the projection optical unit 29 performs the same function as the GI mirrors M2 and M3 of the projection optical unit 10.

[0173] The projection optics unit 29 has exactly three GI mirrors, namely mirrors M2, M4, and M5. The projection optics unit 29 has exactly seven mirrors M1 to M7 between the object field 5 and the image field 11 in the beam path.

[0174] The incident angle sequence of the first three mirrors M1, M2, and M3 in the beam path of the projection optics unit 29 is NI(M1), GI(M2), and NI(M3).

[0175] The incident angle sequence of the seven mirrors M1-M7 of the projection optics unit 29 between the object field 5 and the image field 11 in the beam path is NI, GI, NI, GI, GI, NI, NI.

[0176] The target field 5 and image field 11 are rectangular in the projection optical unit 29.

[0177] The intermediate image ZB in the yz plane (meridian plane) is located in the region of reflection of the imaging light 16 at mirror M5.

[0178] In the xy-plane perpendicular to it, there is no intermediate image between the object field 5 and the image field 11. In the case of the projection optical unit 29, the image plane 12 is the first field of view plane downstream of the object plane 6 of the imaging optical unit 29 in the imaging beam path, in the imaging optical plane that includes the image field width direction x. Image inversion occurs in this imaging optical plane. In contrast, there is no image inversion in the meridional imaging plane due to the intermediate image ZB present there.

[0179] The average wavefront aberration is approximately 13 mλ in the projection optics unit 29.

[0180] The projection optical unit 29 has a total transmittance of 11.1%. The total mirror surface, excluding the polished overrun edge, is 0.83 m for the projection optical unit 29. 2 The total installation height, i.e., the distance between the object plane and the image plane, is 2255 mm. The object-image offset is d. OIS It is 899mm.

[0181] In the projection optics unit 29, an aperture diaphragm or obscuration diaphragm is positioned between mirrors M5 and M6 in the imaging beam path. This diaphragm is located near mirror M6 and is passed through multiple times by the imaging light. The diaphragm may be designed to be subdivided into multiple sub-diaphragms.

[0182] The following tables summarize the parameters and optical design of the projection optics unit 29. Regarding its structure, these tables correspond to those already described above with respect to Figure 2.

[0183] [Table 23]

[0184] [Table 24]

[0185] [Table 25]

[0186] [Table 26]

[0187] [Table 27]

[0188] [Table 28] TIFF2026511986000076.tif200163 TIFF2026511986000077.tif200163

[0189]

Table 29

[0190]

Table 30

[0191] Figures 16 and 17 show further embodiments of the projection optical unit or imaging optical unit 30, which can be used in the projection exposure apparatus 1 instead of the projection optical unit 10 of the embodiment according to FIG. 2. With respect to FIGS. 1 to 15, particularly with respect to FIGS. 1 to 3, the components and functions corresponding to those already described above are denoted by the same reference numerals, and detailed description thereof is omitted.

[0192] Regarding the basic structure, the projection optical unit 30 according to FIGS. 16 and 17 is the same as the projection optical unit 27 according to FIG. 10. The essential difference is that, instead of the two GI mirrors M2 and M3 of the projection optical unit 27, in this case, exactly one GI mirror, namely the GI mirror M2, is used in the projection optical unit 30. In the beam path of the meridional plane according to FIG. 16, this GI mirror M2 has a counterclockwise deflection effect.

[0193] The mirrors M1 and M3 to M7 of the projection optical unit 30 correspond to the mirrors M1 and M4 to M8 of the projection optical unit 27 in terms of their deflection effect.

[0194] Similar to the projection optical unit 29, the projection optical unit 30 according to FIGS. 16 and 17 also has an incident angle sequence NI, GI, NI for the first three mirrors M1 to M3 between the object field 5 and the image field 11 in the imaging beam path.

[0195] Here too, the projection optical unit 30 has exactly three GI mirrors, namely, mirrors M2, M4, and M5. The projection optical unit 30 has exactly seven mirrors between the object field 5 and the image field 11 in the beam path. Similar to the projection optical unit 29, the projection optical unit 30 also has an incident angle sequence NI, GI, NI, GI, GI, NI, NI.

[0196] The object field 5 and the image field 11 are rectangular in the projection optical unit 30.

[0197] Similar to the projection optical unit 27, the projection optical unit 30 also has a meridional intermediate image ZB existing in the form of a fire surface, and there is no intermediate image in the plane perpendicular thereto (FIG. 17). The meridional intermediate image ZB (FIG. 16) is located in the region of the imaging beam path of the projection optical unit 30 between the mirrors M3 and M4.

[0198] In the case of the projection optical unit 30, the aperture stop or the obscuration stop is located in the vicinity of the second last mirror M6. The average wavefront aberration rms is approximately 8 mλ. The total transmittance of the projection optical unit 30 is approximately 11.2%. The total mirror surface including the polished overrun edge is 0.89 m for the projection optical unit 30 2 and is. The distance between the object plane 6 and the image plane 12 is 2278 mm. The object-image offset d OIS is 987 mm in the projection optical unit 30.

[0199] The following table summarizes the parameters and optical design of the projection optical unit 30. Regarding its structure, these tables correspond to those already described above with respect to FIG. 2.

[0200]

Table 31

[0201]

Table 32

[0202]

Table 33

[0203]

Table 34

[0204]

Table 35

[0205]

Table 36

[0206]

Table 37

[0207] [Table 38] TIFF2026511986000096.tif200153 TIFF2026511986000097.tif200153

[0208] Figures 18 and 19 show further embodiments of the projection optical unit or imaging optical unit 31, which may be used in the projection exposure apparatus 1 instead of the projection optical unit 10 in the embodiment according to Figure 2. With respect to Figures 1 to 17, and in particular with respect to Figures 1 to 3, components and functions corresponding to those already described above are indicated by the same reference numerals and a detailed description is omitted.

[0209] Regarding the basic structure, the projection optical unit 31 shown in Figures 18 and 19 is similar to the projection optical unit 30 shown in Figures 16 and 17. The deflection effects of the three GI mirrors M2, M4, and M5 are exactly opposite in the projection optical unit 31 compared to the projection optical unit 30. In the case of the projection optical unit 30, mirror M2 has a counterclockwise deflection effect in the meridian cross-section shown in Figure 16, mirror M4 has a clockwise deflection effect, and mirror M5 again has a counterclockwise deflection effect.

[0210] In the case of the projection optical unit 31, mirror M2 has a clockwise deflection effect in the meridian cross-section shown in Figure 18, mirror M4 has a counterclockwise deflection effect, and mirror M5 again has a clockwise deflection effect.

[0211] The object field 5 and image field 11 are rectangular in the projection optics unit 31.

[0212] The projection optics unit 31 has a meridional intermediate image ZB between two GI mirrors M4 and M5 in the imaging beam path. In a plane perpendicular to this (Figure 19), there is no intermediate image between the object field 5 and the image field 11 in the imaging beam path. In the case of the projection optics unit 31, the aperture or obscuration is located near the second-to-last mirror M6. The mean wavefront aberration rms is approximately 10.4 mλ. The total transmittance in the projection optics unit 31 is approximately 11%. The total mirror surface, excluding polished overrun edges, is 0.74 mλ in the case of the projection optics unit 31. 2 The distance between object plane 6 and image plane 12 is 1963 mm. Object-image offset d OIS It is 1,100 mm.

[0213] The following tables summarize the parameters and optical design of the projection optics unit 31. Regarding its structure, these tables correspond to those already described above with respect to Figure 2.

[0214] [Table 39]

[0215] [Table 40]

[0216] [Table 41]

[0217] [Table 42]

[0218] [Table 43]

[0219] [Table 44] TIFF2026511986000104.tif222160

[0220] [Table 45] TIFF2026511986000106.tif222162

[0221] [Table 46] TIFF2026511986000108.tif222153

[0222] Depending on the embodiment of the projection optics unit described above, the projection optics unit may have a different number of NI mirrors and / or GI mirrors, for example, three or fewer or five or more GI mirrors, for example, exactly one GI mirror, exactly two GI mirrors, or exactly three GI mirrors. Three or fewer or five or more NI mirrors, for example, two, three, or five NI mirrors, are also possible.

[0223] To manufacture microstructures or nanostructure components, the projection exposure apparatus 1 is used as follows: First, a reflective mask 7 or reticle and a substrate or wafer 13 are provided. Then, the structure on the reticle 7 is projected onto the photosensitive layer of the wafer 13 using the projection exposure apparatus 1. Subsequently, the microstructure or nanostructure on the wafer 13, and thus the microstructure component, is manufactured by developing the photosensitive layer.

Claims

1. An imaging EUV optical unit (10; 27; 28; 29; 30, 31) for imaging an object field (5) onto an image field (11), - A plurality of mirrors (M1 to M8) are provided to guide EUV imaging light (16) with a wavelength shorter than 30 nm along the imaging beam path from the object field (5) to the image field (11), - The total transmittance of the plurality of mirrors (M1 to M8) to the EUV imaging light (16) is greater than 5%, - Imaging EUV optical units (10;27;28;29;30, 31) wherein the image field (11) of the imaging optical units (10;27;28;29;30, 31) has a maximum extent of more than 50 mm on the image plane (6).

2. 1.5m 2 The imaging EUV optical unit according to claim 1, characterized by a total mirror surface smaller than [a certain value].

3. The imaging scale (β) in two imaging optical planes (xz, yz) that include two right-angle image field width directions (x, y). x , β y The imaging EUV optical unit according to claim 1 or 2, characterized in that the ) is different.

4. The displacement direction imaging scale (β) in one of the two imaging optical planes (yz) includes the object displacement direction (y) of the object (7) being imaged. y The absolute value of ) is the cross-dimensional imaging scale (β) in the other (xz) of the two imaging optical planes that is perpendicular to the object displacement direction (y). x The imaging EUV optical unit according to any one of claims 1 to 3, characterized in that it is at least 1.1 times the size of ).

5. An imaging EUV optical unit according to any one of claims 1 to 4, characterized by at least one intermediate image (ZB) in at least one imaging optical plane (yz; xz, yz) that includes the image field width direction (x, y).

6. The imaging EUV optical unit according to any one of claims 1 to 5, characterized in that the image plane (12) of the imaging optical unit (10;27;29;30;31) in the imaging beam path in the imaging optical plane (xz) including the image field width direction (x) is the first field of view downstream of the object plane (6) of the imaging optical unit (10;27;29;30;31).

7. The imaging EUV optical unit according to any one of claims 1 to 6, characterized in that the image field (11) has a curved shape.

8. The imaging EUV optical unit according to any one of claims 1 to 7, characterized in that the image field (11) has a double arch shape.

9. An imaging EUV optical unit according to any one of claims 1 to 8, comprising at least four NI mirrors (M1, M4, M7, M8; M1, M3, M6, M7).

10. An imaging EUV optical unit according to any one of claims 1 to 9, comprising at least four GI mirrors (M2, M3, M5, M6).

11. The imaging EUV optical unit according to any one of claims 1 to 10, characterized by at least one pair (M2, M3; M5, M6; M4, M5) of GI mirrors directly continuous within the beam path.

12. The imaging EUV optical unit according to any one of claims 1 to 11, characterized in that the incident angle sequence NI, GI, NI of the first three mirrors (M1 to M3) in the imaging beam path.

13. The imaging EUV optical unit according to any one of claims 1 to 12, characterized by three or fewer GI mirrors (M2, M4, M5) and / or seven or fewer mirrors (M1 to M7) in the imaging beam path.

14. - An illumination optical unit (4) for illuminating the object field (5) with imaging light (16), - The imaging optical unit (10) according to any one of claims 1 to 13 and An optical system equipped with

15. A projection exposure apparatus comprising the optical system described in claim 14 and an EUV light source (3).

16. - A method step of providing the reticle (7) and wafer (13), - A method of projecting a structure on the reticle (7) onto the photosensitive layer of the wafer (13) using the projection exposure apparatus described in claim 15, - A method for generating microstructures and / or nanostructures on the wafer (13) A method for manufacturing structural components, including [the specified element].

17. A structural component manufactured according to the method of claim 16.

Images