Imaging EUV optical unit for imaging object field to image field

Abstract

An imaging EUV optical unit (10) for imaging an object field (5) to an image field (11). A plurality of mirrors (M1 to M8) are used to guide EUV imaging light (16) having a wavelength shorter than 30 nm along an imaging beam path from the object field (5) towards the image field (11). The total transmission rate of the EUV imaging light (16) by the plurality of mirrors (M1 to M8) is greater than 5%. An image field (11) of the imaging optical unit (10) has a maximum range greater than 26 mm in the image plane (6). This results in an imaging EUV optical unit that improves the availability of an EUV projection exposure apparatus.

Description

[0001] This patent application claims priority to German patent application DE 10 2023 203 225.2, the contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to an imaging EUV optical unit for imaging an object field onto an image field. Furthermore, this invention relates to an optical system having this imaging optical unit, a projection exposure apparatus having this optical system, a method for producing micron or nanostructured components using this projection exposure apparatus, and micron or nanostructured components produced by this method. Background Technology

[0003] Projection optical units of the type described at the beginning are known from the following: WO 2018 / 010 960A1, DE 10 2015209 827A1, DE 10 2012 212 753A1, US2010 / 0149509 A1, US 4,964,706, DE 10 2016 218996 A1, and DE 10 2019 202 759 A1. Summary of the Invention

[0004] The object of this invention is to develop an imaging EUV optical unit of the type described at the beginning of this document, thereby improving its usability for EUV projection exposure equipment.

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

[0006] According to the present invention, it can be recognized that imaging EUV optical units with high transmission rates and large maximum image field ranges can be designed compared to existing technologies. For example, this allows for the simultaneous exposure of two fields to be exposed (i.e., two exposure fields) arranged adjacent to each other in the direction of maximum image field extension on a substrate disposed in the image field. This results in a corresponding increase in the yield of the projection exposure apparatus using the imaging EUV optical unit. The maximum range of the image field in the image plane is given by the maximum image field range in the image plane, within which the image field meets the specified imaging quality standards.

[0007] The image-side numerical aperture of the EUV imaging optical unit may not exceed 0.5. For example, the image-side numerical aperture may be less than 0.5, not more than 0.4, and may be 0.33.

[0008] The total surface area of ​​the reflector (which represents the sum of all the reflector surfaces used by multiple reflectors, i.e., the sum of all the reflectors in the imaging EUV optical unit required to guide the imaging light) can be less than 1.5m. 2 It can be less than 1.25m 2It can be less than 1.0m 2 It can be less than 0.8m 2 It can be less than 0.76m 2 It can be less than 0.75m 2 It can be 0.71m 2 It can be less than 0.7m 2 And it can be 0.69m 2 .

[0009] The imaging EUV optical unit may include more than four mirrors for guiding EUV imaging light, more than six mirrors for guiding EUV imaging light, or eight mirrors for guiding EUV imaging light.

[0010] For a given EUV source power, an EUV overall transmittance exceeding 5% can increase the EUV throughput to the image field, thereby increasing the exposure power. Alternatively, for a given desired exposure power on the image field, a smaller power source can be used.

[0011] The overall transmittance of the imaging EUV optical unit can be greater than 10%, 11%, 12%, 13%, 14%, or even 15%. Due to the number of mirrors and the individual EUV transmittance of the mirrors guiding the imaging light (usually not exceeding 80%), the overall transmittance is typically less than 20%.

[0012] When specifying the overall transmission rate, all mirrors of the imaging EUV optical unit in the path that guides the desired imaging beam need to be taken into account.

[0013] The maximum image field range is preferably an integer multiple of the exposure field range in the direction of the maximum image field extension.

[0014] Modified embodiments of the imaging optics unit of claim 3 have been considered advantageous, particularly for optimizing the illumination and guiding of imaging light in the region of a reflective object. US 9,366,968 B2 discloses an example of a deformable projection optics unit.

[0015] The imaging scales described in claim 4 have particularly demonstrated their value. Specifically, objects of standard width can still be processed on the object side despite a large image field. In absolute terms, the imaging scale in the displacement direction can, for example, be twice as large as the imaging scale in the lateral dimension. In the case of absolute value comparisons, the imaging scale is specified as a reduction factor.

[0016] The at least one intermediate image as described in claim 5 allows for a smaller mirror surface of the mirror to be designed in the region of the intermediate image.

[0017] In the embodiment of claim 6, the imaging EUV optical unit does not have an intermediate image perpendicular to the meridional plane. Image flipping exists in the sagittal plane perpendicular to the meridional plane. Therefore, an imaging optical unit of the choristikonal type, as defined in US10,656,400B2, can exist, wherein different numbers of intermediate images exist in mutually perpendicular imaging light planes.

[0018] The arc-shaped field (which can be implemented as a ring field) described in claim 7 enables the EUV optical unit to have good imaging correction.

[0019] The double-arched image field of claim 8 is well-suited for the symmetry of exposures of two exposure fields arranged adjacent to each other along the maximum image field range. A double-arched field design can be provided where the field range perpendicular to the maximum field extension direction is reduced compared to a simple arch spanning the entire maximum field range.

[0020] Practice has shown that providing the plurality of mirrors as described in claims 9 and 10 is valuable. An advantageous combination of image field correction and transmission can be obtained.

[0021] According to claim 11, adjacent GI mirrors in the beam path have proven their value in guiding the imaging light. An imaging EUV optical unit may contain two such GI mirror pairs. The deflection effects of the individual GI mirrors within a GI mirror pair may be additive or subtractive.

[0022] The incident angle sequence of claim 12 has proven its value in practice.

[0023] If the imaging optical unit of claim 13 has no more than three GI mirrors, it may have an advantage in throughput. Similarly, if the imaging optical unit of claim 13 has no more than seven mirrors in total, it may also have an advantage in throughput.

[0024] The imaging optics unit may contain exactly three GI mirrors. In this case, exactly two of the three GI mirrors may be designed as adjacent mirror pairs. Such mirror pairs with two adjacent GI mirrors may be designed such that the deflection effects of the two GI mirrors are additive, or may be designed such that the deflection effects of the two GI mirrors are subtractive.

[0025] The imaging optics unit can contain exactly seven mirrors in the imaging beam path between the object field and the image field. In this case, the order of the incident angles can be as follows: NI, GI, NI, GI, GI, NI, NI.

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

[0027] For example, the EUV light source of a projection exposure device can be designed to use wavelengths no greater than 13.5 nm, less than 13.5 nm, less than 10 nm, less than 8 nm, less than 7 nm, and 6.7 nm or 6.9 nm. Wavelengths less than 6.7 nm, and especially on the order of 6 nm, are also possible.

[0028] In particular, projection exposure equipment can be used to produce semiconductor components, such as memory chips. Attached Figure Description

[0029] At least one exemplary embodiment of the present invention will now be described based on the accompanying drawings. In the drawings:

[0030] Figure 1 A meridional section of a projection exposure apparatus used for EUV projection lithography is schematically shown;

[0031] Figure 2 The meridian profile is shown as the basis Figure 1 An embodiment of the imaging optical unit of the projection lens in a projection exposure device, wherein the imaging beam paths of the principal rays and the upper and lower coma rays at two selected field points are illustrated.

[0032] Figure 3 Showing from Figure 2 The basis of observation direction III Figure 2 A view of the imaging optical unit;

[0033] Figure 4 A plan view of a wafer exposed by a projection exposure device is shown, highlighting the individual exposure fields to be scanned in a rectangular shape on the substrate to be exposed;

[0034] Figure 5 Showing Figure 4 The enlarged plan view of detail V shows the scan path of the image field (rectangular in this case) of the projection lens on the wafer by way of example. The solid line shows the scan path during the projection exposure time of the projection exposure device, and the dashed line shows the scan path during the exposure pause time.

[0035] Figure 6 With similar Figure 5 The diagram shows that, according to Figure 5The scanning path of the arched or ring-shaped field of the projection optical unit on the wafer cross section is another option in this regard;

[0036] Figure 7 With similar Figure 5 The schematic diagram shows the same wafer cross-section and scan path when using a rectangular image field, compared to Figure 5 In comparison, the field width perpendicular to the scanning direction is twice as large;

[0037] Figure 8 In similar Figure 7 The schematic diagram shows the scanning path when using an alternative projection optical unit, for example, characterized by compared to Figure 6 It has an arched or ring-shaped field with an image field width perpendicular to the scanning direction, which is twice that of the scanning direction.

[0038] Figure 9 In similar Figure 7 The schematic diagram shows the scanning path when using a double-arched image field with a projection optics unit, which is another alternative in this regard. Figure 6 Compared to having twice the image field width again, the double-arched image field can be understood as being based on Figure 6 The two arched or annular fields are placed adjacent to each other perpendicular to the scanning direction;

[0039] Figure 10 and Figure 11 With similar Figure 2 and Figure 3 The diagram shows what can be used as a basis Figure 1 Another embodiment of the imaging optical unit of the projection lens in a projection exposure device;

[0040] Figure 12 and Figure 13 With similar Figure 2 and Figure 3 The diagram shows what can be used as a basis Figure 1 Another embodiment of the imaging optical unit of the projection lens in a projection exposure device;

[0041] Figure 14 and Figure 15 With similar Figure 2 and Figure 3 The diagram shows what can be used as a basis Figure 1 Another embodiment of the imaging optical unit of the projection lens in a projection exposure device;

[0042] Figure 16 and Figure 17 With similar Figure 2 and Figure 3 The diagram shows what can be used as a basis Figure 1Another embodiment of the imaging optical unit of the projection lens in a projection exposure device;

[0043] Figure 18 and Figure 19 With similar Figure 2 and Figure 3 The diagram shows what can be used as a basis Figure 1 Another embodiment of the imaging optical unit of the projection lens in a projection exposure device. Detailed Implementation

[0044] In the following text, examples will be used as a reference. Figure 1 This section describes the basic components of the microlithography projection exposure apparatus 1. The description of the basic structure and components of the projection exposure apparatus 1 herein should not be construed as restrictive.

[0045] In addition to the light source or radiation source 3, one embodiment of the illumination system 2 of the projection exposure apparatus 1 also includes an illumination optics unit 4 for illuminating the object field 5 in the object plane 6. In an alternative embodiment, the light source 3 may also be provided as a module independent of the rest of the illumination system. In this case, the illumination system does not include the light source 3.

[0046] The mask master 7, positioned in the object field 5, is exposed. The mask master 7 is held by the mask master holder 8. The mask master holder 8 can be displaced by means of the mask master displacement driver 9, particularly in the scanning direction.

[0047] The projection exposure apparatus 1 includes a projection optics unit or an imaging optics unit 10. The projection optics unit 10 is used to image the object field 5 onto an image field 11 in an image plane 12. The image plane 12 extends parallel to the object plane 6. Alternatively, it is possible that the angle between the object plane 6 and the image plane 12 is not equal to 0°.

[0048] For explanatory purposes, Figure 1 This displays a Cartesian xyz coordinate system. The x-direction is perpendicular to the drawing plane and extends into it. The y-direction extends horizontally, and the z-direction extends vertically. The scan direction is along... Figure 1 It extends in the y-direction. The z-direction extends perpendicular to the image plane 12.

[0049] The structure on the master mask 7 is imaged onto the photosensitive layer of the wafer 13, which is positioned in the region of the image field 11 in the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be displaced by means of a wafer displacement driver 15, particularly in the y-direction. The master mask 7 is first displaced by the master mask displacement driver 9, and then the wafer 13 is displaced by the wafer displacement driver 15, thereby achieving synchronization between them.

[0050] Radiation source 3 is an EUV radiation source. Specifically, radiation source 3 emits EUV radiation 16, which is also referred to hereinafter as operational radiation or illumination radiation. Specifically, the operational radiation has a wavelength in the range of 5 nm to 30 nm. Radiation source 3 can be a plasma source, such as an LPP (laser-generated plasma) source or a GDPP (gas discharge-generated plasma) source. It can also be a synchrotron-based radiation source. Radiation source 3 can be a free-electron laser (FEL).

[0051] Illumination radiation 16 emitted from radiation source 3 is focused by concentrator 17. Concentrator 17 may be a concentrator having one or more elliptical and / or hyperboloidal reflective surfaces. Illumination radiation 16 may be incident on at least one reflective surface of concentrator 17 at grazing incidence (GI) (i.e., an incident angle greater than 45°) or at normal incidence (NI) (i.e., an incident angle less than 45°). Concentrator 17 may be structured and / or coated, on the one hand to optimize its reflectivity for the radiation used, and on the other hand to suppress stray light.

[0052] The illumination radiation 16 propagates through the intermediate focal point in the intermediate focal plane 18 downstream of the light collector 17. The intermediate focal plane 18 can represent the interval between the radiation source module containing the radiation source 3 and the light collector 17 and the illumination optical unit 4.

[0053] The illumination optical unit 4 includes a first faceted mirror 19. If the first faceted mirror 19 is arranged in the plane of the illumination optical unit 4 which is optically conjugate to the object plane 6, this faceted mirror is also referred to as a field faceted mirror. The first faceted mirror 19 includes a plurality of individual first facets 20, which are also referred to below as field facets. Figure 1 Only some of these facets are shown in an exemplary manner.

[0054] The first facet 20 can be implemented as a macro-facet, particularly a rectangular facet or a facet with an arcuate edge profile or a portion of a circle. The first facet 20 can be implemented as a planar facet or alternatively as a facet with convex or concave curvature.

[0055] For example, as known from DE 10 2008 009 600 A1, the first facet 20 itself can, in various cases, be composed of multiple individual mirrors, particularly multiple micromirrors. The first facet mirror 19 can be specifically configured as a microelectromechanical system (MEMS system). See DE 10 2008 for details.

[0056] 009 600A1.

[0057] The deflector US can be implemented as a plane mirror, but it can also alternatively have a beamforming effect. The deflector US is located in the beam path of the illumination optics unit 4, between the central focal point in the intermediate focal plane 18 and the first faceted mirror 19. In particular, depending on the configuration of the light source 3, the deflector US may also be omitted.

[0058] In the beam path of the illumination optical unit 4, the second faceted mirror 21 is positioned downstream of the first faceted mirror 19. If the second faceted mirror 21 is positioned in the pupil plane EP of the illumination optical unit 4, it is also called a pupil faceted mirror. The second faceted mirror 21 can also be positioned at a certain distance from the pupil plane of the illumination optical unit 4. In this case, the combination of the first faceted mirror 19 and the second faceted mirror 21 is also called a specular reflector. Specular reflectors have been disclosed in US2006 / 0132747 A1, EP 1 614 008 B1, and US 6,573,978.

[0059] The second faceted reflector 21 comprises multiple second facets 22. In the case of a pupil faceted reflector, the second facet 22 is also called a pupil facet.

[0060] The second facet 22 can also be a macroscopic facet, which may, for example, have circular, rectangular, or hexagonal boundaries, or alternatively, a facet composed of micromirrors. In this regard, see also DE 102008 009 600A1.

[0061] The second facet 22 may have a planar reflective surface or alternatively a reflective surface with convex or concave curvature.

[0062] Therefore, the illumination optics unit 4 forms a biplane system. This basic principle is also known as a fly-eye condenser (fly-eye integrator).

[0063] It may be advantageous to imprecisely position the second faceted mirror 21 on a plane optically conjugate with the pupil plane of the projection optics unit 10. In particular, the pupil faceted mirror 21 may be configured to be tilted relative to the pupil plane of the projection optics unit 10, for example, as described in DE 10 2017 220 586 A1.

[0064] With the assistance of the second faceted mirror 21 and selectively in the imaging optical assembly in the form of a transmission optical unit ( Figure 1 With the assistance of (not shown), each of the first facets 20 is imaged into the object field 5.

[0065] The transmission optics unit may have exactly one mirror, or two or more mirrors, arranged one after the other in the beam path of the illumination optics unit 4. Specifically, the transmission optics unit may include one or two normal-incident mirrors (NI mirrors) and / or one or two grazing-incident mirrors (GI mirrors). Figure 1 In the illustrated embodiment, the illumination optical unit 4 has exactly three mirrors, namely, downstream of the light collector 17, specifically a deflecting mirror US, a first faceted mirror 19, and a second faceted mirror 21.

[0066] When the transmission optics unit downstream of the second faceted mirror 21 is omitted, the second faceted mirror 21 is either the last beamforming mirror or the last mirror reflecting the illumination radiation 16 in the beam path upstream of the object field 5. (WO2019 / 096654 A1) Figure 2 An example of an illumination optical unit 4 without a transmission optical unit is disclosed.

[0067] Imaging the first plane 20 onto the object plane 6 using the second plane 22 or by using the second plane 22 and the transmission optical unit is usually only an approximate imaging.

[0068] The projection optical unit 10 includes multiple mirrors, namely eight mirrors M1 to M8 (see...). Figure 2 These mirrors are numbered sequentially according to their order in the beam path of the projection exposure device 1.

[0069] exist Figure 2 In the example shown, the projection optics unit 10 includes eight mirrors M1 to M8. Four, five, six, or any other number of mirrors Mi can also be selected.

[0070] The projection optical unit 10 is an unobstructed optical unit. None of the reflectors M1 to M8 contain channel openings for illumination radiation 16.

[0071] The image-side numerical aperture of the projection optical unit 10 is 0.33. Depending on the embodiment of the projection optical unit 10, the image-side numerical aperture may range, for example, between 0.25 and 0.4. The image-side numerical aperture of the projection optical unit 10 may also employ different values ​​depending on the embodiment.

[0072] The reflective surface of mirror Mi is implemented as a freeform surface without a rotational axis of symmetry. Alternatively, the reflective surface of mirror Mi can also be designed as an aspherical surface, with exactly one rotational axis of symmetry for its shape. Like the mirror in illumination optics unit 4, mirror Mi can also have a highly reflective coating for illumination radiation 16. These coatings can be designed as multilayer coatings, such as alternating layers of molybdenum and silicon. Ruthenium coatings can also be used, particularly for grazing incidence coated mirrors (GI mirrors).

[0073] The projection optical unit 10 has a size reduction ratio of 2:1 in the x-direction (i.e., in the direction perpendicular to the scanning direction y). The imaging ratio β in the x-direction... x It is -2.00. This imaging scale β x Also known as the horizontal dimension imaging ratio.

[0074] In the scanning direction y, the projection optical unit 10 is reduced in size to 4:1, but in this case, a flip-like (β) effect does not occur. y =+4.00). This imaging scale β y Also known as displacement direction imaging scale.

[0075] The imaging ratio described here is the reduction factor of the projection optical unit 10 when the object field 5 is imaged onto the image field 11.

[0076] Therefore, the projection optical unit 10 has a displacement direction imaging ratio in the scanning direction y of the imaging light plane yz, the absolute value of which is twice the size of the lateral dimension imaging ratio in the lateral scanning direction x of another imaging light plane xz perpendicular to the scanning direction y (i.e., the object displacement direction). The ratio between the displacement direction imaging ratio and the lateral dimension imaging ratio is in the range of 1.1 to 5, for example, it can be 2.

[0077] The projection optical unit 10 has a deformable design. It has different imaging ratios β in the x and y directions. x β y The two imaging ratios β of the projection optical unit 10 x β y The preferred value is (β) x ,β y ) = (+ / -2, / +-4 or + / -8), especially (β) x ,β y ) = (+ / -2,+ / -4) or (+ / -4,+ / -8).

[0078] Other imaging scales can also be used. Imaging scales with the same sign can also be used in the x and y directions.

[0079] When using a morphing projection optical unit, the angle of the main ray of the illumination beam on the mask master 7 can be reduced, while avoiding unnecessary shadowing effects.

[0080] The projection optical unit 10 can also have an isomorphic configuration, that is, an imaging ratio β in the x and y directions. x β x They have the same absolute value.

[0081] The image field 11 of the projection optical unit 10 is rectangular, with an x-range of 52 mm and a y-range of 1.8 mm. Therefore, perpendicular to the scanning direction y of the projection exposure device 1 designed as a scanner, the field range of the image field is twice the y-range of the typical exposure field 23 to be scanned.

[0082] The following will be based on Figures 4 to 7 Especially according to Figure 4 and Figure 7 Let me explain in detail.

[0083] Figure 4 The plan view of wafer 13 is shown. Wafer 13 has rectangular exposure fields 23, which are arranged in a raster manner on wafer 13 and scanned relative to image field 11. Each exposure field 23 typically has a range of 26 mm in the x-direction and a typical range of 32 mm in the y-direction. The standard diameter of wafer 13 is 300 mm.

[0084] Figure 5 An example scan path S is shown on a portion of wafer 13 using a variant of the projection optics unit 10, the image field 11 having a standard range of 26 mm in the x direction, corresponding to the x range of the exposure field 23. Figure 5 The portions of the image field 11 relative to the scanning path S of the wafer 13 are shown in solid lines, and the projection exposure device 1 performs projection exposure on the wafer. During the linear movement of these scanning path portions along the y-direction (i.e., the scanning direction), the image field 11 is scanned over the entire corresponding exposure field 23, resulting in the exposure of the entire exposure field 23.

[0085] Figure 5 An example is given of a scan path S used to expose exactly one adjacent row of exposure fields 23 on wafer 13. Since the exposure portion of the scan path S is correspondingly extended, that is, the portion of the scan path S drawn as a solid line and running straight in the y direction, multiple rows of exposure fields 23 that are adjacent to each other in the y direction can also be exposed on wafer 13.

[0086] Figure 5 The dashed lines in the diagram illustrate the connecting portions of the scan paths S that link adjacent exposure portions in each case; that is, these lines represent the portion of the relative movement of the image field 11 relative to the wafer 13 during the period when the wafer 13 is not exposed. In the illustrated example, each connecting portion has a 180° arched shape.

[0087] Generally, the relative movement of the image field 11 with respect to the wafer 13 is generated by the actuator-based displacement of the wafer 13 relative to the projection optical unit 10 in the y-direction or x-direction.

[0088] According to Figure 5In one embodiment, the image field width is the same as the exposure field width (26 mm), and in each scanning step of the projection exposure device 1, exactly one exposure field 23 or a column portion of an exposure field 23 having adjacent exposure fields 23 are exposed.

[0089] Figure 6 This illustrates the effect when using a variant of the projection optical unit 10 with an arcuate or annular field shape image field 11, compared to... Figure 5 The scanning path S corresponding to the scanning path also has a standard range of 26mm in the x-direction, that is, a width that precisely corresponds to the width of the exposure field 23. (Previously mentioned...) Figure 5 The meaning explained in the context applies here accordingly.

[0090] Figure 7 Showing when using according to Figure 2 The scanning path S when projecting the image field 11 of the optical unit 10, that is, the x-range of the rectangular image field 11 corresponds to twice the x-direction of the corresponding exposure field 23. Using according to Figure 2 The projection optical unit 10 has an image field 11 twice the width of the projection optical unit 10, and simultaneously scans and exposes two adjacent exposure fields 23 in the x direction along the corresponding exposure portion of the scanning path S. Therefore, in each scanning step, according to... Figure 5 and Figure 6 Compared to a projection optical unit with a single-width image field 11, a unit with an image field 11 twice the width is based on... Figure 2 The projection exposure device of the projection optical unit 10 has twice the exposure flux of the exposed exposure field 23. Specifically, the number of unproductive connecting parts (dashed lines) can be reduced by about half relative to the exposure field 23 exposed in each exposure section.

[0091] As an alternative to a rectangular image field 11 with twice the width, an arcuate or partially annular image field 11 with twice the width can also be used, such as... Figure 8 As shown. This bow-shaped or partially annular image field 11 appears in a variant of the projection optical unit 10.

[0092] In another alternative to a rectangular image field 11 that is twice the width, a double-arched image field 11 can also be used, such as... Figure 9 As shown. According to Figure 9 This double-arched image field 11 can be understood as two adjacent arches of a single width placed in the x-direction. Figure 6 The arc-shaped or partially annular image field 11. According to Figure 9 This double-arched image field 11 appears in another variant of the projection optical unit 10.

[0093] In various cases, one of the pupil planes 22 is precisely assigned to one of the field planes 20 to form an illumination channel for illuminating the object field 5. Specifically, this can produce a result consistent with... The principle of illumination. With the assistance of the field plane 20, the far field is decomposed into multiple object fields 5. The field plane 20 produces multiple images with intermediate focal points on the pupil plane 22 respectively assigned to it.

[0094] Through the assigned pupil plane 22, the field plane 20 is imaged onto the master mask 7 in a superimposed manner in each case to illuminate the object field 5. Specifically, the illumination of the object field 5 is made as uniform as possible. The uniformity error is preferably less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

[0095] The illumination of the entrance pupil of the projection optical unit 10 can be geometrically defined by means of the configuration of the pupil facets 22 used. By selecting the illumination channel, and in particular a subset of the pupil facets that guide the light, the intensity distribution in the entrance pupil of the projection optical unit 10 can be set. This intensity distribution is also referred to as illumination setting or illumination pupil filling.

[0096] The same superior pupil uniformity in a portion of the illumination pupil of the illumination optical unit 4, which illuminates in a defined manner, can be achieved by redistributing the illumination channels.

[0097] The projection optical unit 10 is telecentric on the image side.

[0098] The following will describe the various aspects and details of the illumination of the object field 5, especially the various aspects and details of the illumination of the entrance pupil of the projection optical unit 10.

[0099] The projection optics unit 10 may specifically have a concentric entrance pupil. In this case, the pupil facet mirror 21 may be configured in the entrance pupil region of the projection optics unit 10 and then configured on the beam path upstream of the object field 5. Alternatively, the projection optics unit 10 may also have a telecentric embodiment on the object side. If access to the entrance pupil of the projection optics unit 10 is not possible, the configuration plane of the pupil facet mirror 21 may be imaged onto the entrance pupil by means of other components of the illumination optics unit 4.

[0100] Typically, the pupil faceted mirror 21 cannot be used to precisely illuminate the entrance pupil of the projection optics unit 10. When the projection optics unit 10 images the center of the pupil faceted mirror 21 onto the wafer 13 at a telecentric angle, the aperture rays typically do not intersect at a single point. However, a region can be found where the distance between paired, defined aperture rays becomes minimal. This region represents the entrance pupil or a region in real space conjugate with it. In particular, this region has a finite curvature.

[0101] It is possible that the projection optics unit 10 has different entrance pupil orientations for the tangential beam path and the sagittal beam path. In this case, an imaging element, specifically the optical component of the transmission optics unit, should be placed between the second faceted mirror 21 and the mask master 7. This optical element allows for consideration of the different orientations of the tangential and sagittal entrance pupils.

[0102] exist Figure 1 In the component configuration of the illumination optical unit 4 shown, the pupil faceted mirror 21 is configured to be tilted relative to the object plane 6. Furthermore, the second faceted mirror 21 is configured to be tilted relative to the configuration plane defined by the first faceted mirror 19.

[0103] The following will be based on Figure 2 and Figure 3 Further details relating to the projection optical unit 10 are described below.

[0104] The projection optics unit 10 has four NI mirrors (mirrors for normal incidence; normal incidence mirrors), namely mirrors M1, M4, M7, and M8 in the imaging beam path of the projection optics unit 10. Imaging light 16 illuminates these NI mirrors M1, M4, M7, and M8 at an incident angle of less than 45°. The maximum incident angle of the imaging light 16 incident on each NI mirror can be less than 40°, less than 35°, less than 30°, less than 25°, less than 20°, less than 15°, or less than 10°.

[0105] The other mirrors M2, M3, M5, and M6 of the projection optical unit 10 are GI mirrors (grazing incidence mirrors, grazing incidence mirrors). For these mirrors M2, M3, M5, and M6, the incident angle of the illumination light 16 on the mirrors is greater than 45° in each case. The minimum incident angle on each GI mirror can be greater than 50°, greater than 55°, greater than 60°, greater than 65°, greater than 70°, greater than 75°, or greater than 80°.

[0106] For information on reflections in a GI mirror (grazing incidence mirror), see WO 2012 / 126867A. For further information on reflectivity in a NI mirror (normal incidence mirror), see DE 101 55 711A.

[0107] Depending on the embodiment of the projection optics unit 10, there may be more than four NI mirrors and / or fewer or more than four GI mirrors.

[0108] On one hand, there's the deflection effect of mirrors M2 and M3; on the other hand, there's the deflection effect of mirrors M5 and M6. The two are added together. Therefore, according to... Figure 2The projection optical unit 10 has two GI mirror pairs, and the deflection effects of the GI mirrors in the GI mirror pairs are additive in all cases.

[0109] The four NI mirrors M1, M4, M7 and M8 have a deflection effect that is subtractive of each other. As a result, the imaging beam path is guided on these four NI mirrors M1, M4, M7 and M8 in a zigzag pattern between the object field 5 and the image field 11.

[0110] None of the mirrors M1 to M8 have channel openings, and in each case, these mirrors are used in a reflective manner in a continuous area without gaps.

[0111] Figure 2 The calculated reflective surfaces of mirrors M1 to M8 are shown. The reflective surfaces used by mirrors M1 to M8 are supported by a mirror body (not shown) in a known manner. Without considering polishing overflow, the overall mirror surface area of ​​the projection optics unit 10 is 0.71 μm. 2 .

[0112] The object plane 6 and the image plane 12 extend parallel to each other and are very close.

[0113] The reflecting surface of the third-to-last mirror M6 in the imaging beam path faces the last mirror.

[0114] M8. Therefore, the imaging beam path is guided around the last mirror M8. Between mirrors M4 and M7, the imaging beam path of imaging light 16 is guided around mirror M8 with the assistance of two GI mirrors M5 and M6.

[0115] In the case of projection optical unit 10, the number of intermediate image planes in the x and y directions of the beam path between object field 5 and image field 11 is different. In the yz plane, projection optical unit 10 has a caustic intermediate image ZB in the region of intermediate image configuration plane 24 on the imaging beam path between mirrors M5 and M6, such as... Figure 2 The meridional profile is shown. 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 point of the projection optical unit 10.

[0116] In the imaging direction perpendicular to it, the imaging scale β x = -2.00, the projection optical unit 10 has no intermediate image, which can be seen from Figure 3As can be seen in the view, image plane 12 is the first field plane after object plane 6 in the xz principal plane of the projection optics unit 10 (i.e., in the imaging beam path of the projection optics unit 10 perpendicular to the yz meridional plane). Therefore, the projection optics unit 10 does not have an intermediate image perpendicular to the meridional plane. Therefore, there is an image flip perpendicular to the meridional plane.

[0117] Examples of projection optical units with different numbers of such intermediate images in the x and y directions or on mutually perpendicular imaging light planes are known from US2018 / 10656400B2. Alternatively, 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.

[0118] The object field 5 and the image field 11 are offset from each other by a distance d in the y direction. OIS (Image offset). Image offset d OIS The measurement is performed between the center point of object field 5 and the center point of image field 11, using a normal N perpendicular to image plane 12. Object-image offset d OIS It is 910 mm.

[0119] According to Figure 2 In the projection optics unit 10, the overall transmittance of the projection optics unit 10 is 10.2%, where the overall transmittance is the product of the EUV reflectance of the mirrors M1 to M8 for the illumination light 16 along the imaging beam path passing through the projection optics unit 10. Therefore, on average, M1 to

[0120] Each mirror in the M8 system has a reflectivity of over 75%.

[0121] Therefore, the overall transmission rate of mirrors M1 to M8 (i.e., the overall transmission rate of projection optical unit 10) is greater than 5%. The overall transmission rate of projection optical unit 10 can be greater than 6%, greater than 7%, greater than 8%, greater than 9%, or greater than 10%. Due to the number of mirrors and the individual EUV transmission rates of the mirrors guiding the imaging light (which typically do not exceed 80%), the overall transmission rate is typically less than 15%.

[0122] In the yz plane, the first pupil plane of the projection optics unit 10 is located on the beam path of the imaging light 16 in the reflection region at the mirror M2. The second pupil plane in the yz plane is located at the same position as the pupil plane in the xz plane perpendicular to it, at a position in the imaging beam path between mirrors M7 and M8. In the case of the projection optics unit 10, the aperture can be limited by means of an aperture stop, which specifically limits the imaging beam path on the edge side, and the aperture stop can be mounted between mirrors M7 and M8. If necessary, an internal blockage can also be defined by means of an appropriate aperture stop portion. In the case of the projection optics unit 10, the aperture stop is particularly present in the form of a plurality of aperture stop portions arranged separately from each other. For example, US10,527,832 discloses the concept of a plurality of aperture stop portions. In the projection optics unit 10, these aperture stop portions are partially arranged between mirrors M7 and M8 and in the beam path of the illumination light 16 at the position of mirror M7.

[0123] In the case of projection optical unit 10, the distance between object plane 6 and image plane 12 is 1708 mm.

[0124] Mirrors M1 to M8 carry a coating that optimizes the reflectivity of mirrors M1 to M8 for imaging light 16. Specifically, for GI mirrors, this can be a lanthanum coating, a boron coating, or a boron coating with lanthanum as the outermost layer, or a ruthenium coating. Other coating materials can also be used, particularly lanthanum nitride and / or B4C. In mirrors M2, M3, M5, and M6 for grazing incidence, a coating having, for example, a layer of boron or lanthanum can be used. High-reflectivity layers (particularly for mirrors M1, M4, M7, and M8 for normal incidence) can be configured as multilayers, where successive layers can be made of different materials. Alternating material layers can also be used. A typical multilayer material layer can have 50 bilayers, each formed by a boron layer and a lanthanum layer. Layers containing lanthanum nitride and / or boron (particularly B4C) can also be used.

[0125] Table 1 below summarizes the parameters of the projection optics unit 10. In addition to the data already explained above, Table 1 also specifies the following values: the angle of the principal ray at the center field point relative to the z-axis, the available light spread of the projection optics unit, and the mean wavefront aberration RMS.

[0126] wavelength 13.5nm Image-side numerical aperture 0.33 Image field size in the x and y directions 52mm×1.80mm <![CDATA[β x ]]> -2.00 (No intermediate image) <![CDATA[β y ]]> 4.00 (with center image) Main ray angle 6° Light Spread <![CDATA[10.19mm 2 ]]> Mean wavefront aberration RMS 6.6mλ Overall transmission rate 10.2％ Position of the entrance pupil (x) -1349mm Position of the entrance pupil (y) -1897mm Object-image offset in the y direction 910mm Distance between M7 and the image plane 94mm Distance between object plane and image plane 1708mm Inclination between the object plane and the image plane 0° Installation space cube (586×1056×1224)mm

[0127] Figure 2 Table 1

[0128] The z-range of the mounting space cube represents the maximum z-distance between the optical surfaces used, i.e., in the example of the projection optical unit 10, the maximum z-distance between the optical surface portions of the reflector M4 and the reflector M7.

[0129] Tables 2a and 2b below summarize the parameters of the reflectors M1 to M8 of the projection optical unit 10: "maximum incident angle", "reflective surface range in the x direction", "reflective surface range in the y direction", and "maximum reflector diameter".

[0130] M1 M2 M3 M4 Maximum angle of incidence [°] 17.9 83.9 85.7 21.6 Minimum angle of incidence [°] 12.4 71.7 81.3 17.8 The extent of the reflective surface in the x-direction [mm] 586.5 561.2 553.5 550.7 The range of the reflective surface in the y-direction [mm] 215.0 214.5 336.4 49.8 Maximum reflector diameter [mm] 586.6 561.3 570.6 550.9

[0131] Figure 2 Table 2a

[0132] M5 M6 M7 M8 Maximum angle of incidence [°] 82.0 86.3 25.3 14.3 Minimum angle of incidence [°] 77.1 79.9 4.0 7.8 The extent of the reflective surface in the x-direction [mm] 530.5 449.9 342.3 393.8 The range of the reflective surface in the y-direction [mm] 218.5 292.3 89.7 353.4 Maximum reflector diameter [mm] 534.3 451.4 342.3 394.1

[0133] Figure 2 Table 2b

[0134] The reflector surfaces of mirrors M1 to M8 shown have no polished overflow. The actual reflector surfaces of mirrors M1 to M8 include the reflective surface actually used to reflect the imaging light 16 and a polished overflow with a radius of approximately 20 mm. Therefore, there is an overhang in the form of polished overflow of at least 10 mm, and generally 20 mm, between the reflector surface used for reflection and the unpolished area of ​​the reflector surface.

[0135] The overall surface area of ​​the reflecting mirror is less than 1.5m. 2 This represents the total surface area of ​​mirrors M1 to M8 actually used for reflection, excluding polishing overflow. Polishing overflow is included in this overall mirror surface. According to... Figure 2 In the projection optical unit 10, the surface area of ​​this integral reflector is 0.71m. 2 If polishing overflow is taken into account, the overall surface area of ​​the reflector is 0.92m. 2 .

[0136] Reflectors M1 to M8 are implemented as freeform surfaces that cannot be described by rotational symmetry functions. Other embodiments of the projection optical unit 10 are also possible, wherein at least one of the reflectors M1 to M6 is implemented as a rotationally symmetric aspheric surface. Alternatively, all reflectors M1 to M6 may be implemented as such aspheric surfaces.

[0137] A freeform surface can be described by the following freeform surface equation (Equation 1):

[0138]

[0139] The following parameters apply to this equation (1):

[0140] Z is the sagittal height of the freeform surface at points x and y, where x 2 +y 2 =r 2 Here, r is the distance from the reference axis (x = 0; y = 0) of the freeform surface equation.

[0141] In the freeform surface equation (1), C1, C2, C3... represent the coefficients of the freeform surface series expansion with powers of x and y.

[0142] In the case of a conical base, c x c y It is a constant corresponding to the curvature of the vertex of the corresponding aspherical surface. Therefore, c x =1 / R x (1 / RDX) and c y =1 / R y (1 / RDY) Applicable. k x and k y (CCX, CCY) each correspond to the conic constant of the corresponding aspherical surface. Therefore, equation (1) describes the biconical freeform surface.

[0143] Another possible freeform surface can be generated from a rotationally symmetric reference surface. Such a freeform surface of the reflective surface of the mirror of the projection optics unit used in a microlithography projection exposure apparatus is known from US20070 058 269A1.

[0144] Alternatively, freeform surfaces can also be described using two-dimensional spline surfaces. This paradigm includes Bezier curves or non-uniform rational fundamental splines (NURBS). For example, a two-dimensional spline surface can be described using a point grid in the xy-plane and associated z-values, or using these points and their associated gradients. Depending on the type of spline surface, the complete surface is obtained using interpolation between grid points, employing polynomials or functions with specific properties regarding their continuity and differentiability. This paradigm uses analytical functions.

[0145] The optical design data for the reflective surfaces of the reflectors M1 to M8 of the projection optical unit 10 can be found in the further table below.

[0146] Table 3 lists the coordinates of the surface origin of the corresponding mirror surface and the region of object field 5, relative to the xyz coordinate system of image field 11.

[0147] The first column specifies the distances of the corresponding mirror or object field 5 from the origin of the coordinate system located at the center of the image field 11 in the x direction (first column), y direction (second column), and z direction (third column).

[0148] The additional columns in Table 3 (Table 3b) also specify the tilt values ​​of the respective surfaces or object fields 5 of mirrors M1 to M8 relative to the x-axis, y-axis, and z-axis. According to... Figure 2 In the embodiment, neither the object field 5 nor the image field 11 is tilted relative to the x-axis and extends parallel to each other.

[0149] Table 4 lists the parameters RDX, RDY, CCX, and CCY for mirrors M1 to M8, and lists the values ​​of coefficients C1, C2, C3, ... of the freeform surface series expansion based on the above equation (1) in order of powers of x and y.

[0150] Table 5 lists the reflectivity of mirrors M1 to M8 and the overall transmittance of the projection optical unit 10 (which is 10.2%).

[0151] x-distance [mm] y-distance [mm] z-distance [mm] field 0 909.83 1707.79 M1 0 786.67 536.09 M2 0 594.34 970.93 M3 0 343.25 1192.99 M4 0 132.65 1301.61 M5 0 245.35 1038.26 M6 0 259.20 671.50 Aperture (AS) 0 159.11 176.44 M7 0 143.78 100.64 M8 0 0 517.31 Image field 0 0 0

[0152] Figure 2 Table 3a

[0153]

[0154]

[0155] Figure 2 Table 3b

[0156]

[0157]

[0158]

[0159]

[0160]

[0161]

[0162]

[0163]

[0164]

[0165]

[0166]

[0167]

[0168]

[0169]

[0170]

[0171]

[0172]

[0173]

[0174]

[0175]

[0176]

[0177] Figure 2 Table 4

[0178]

[0179]

[0180] Figure 2 Table 5

[0181] Reflectors with logarithmic RDX and RDY having different signs have saddle point type or minimum basic shape.

[0182] In the case of projection optical unit 10, GI reflector M6 is spatially located next to the last reflector M8.

[0183] Figure 10 and Figure 11 Another embodiment of the projection optics unit or imaging optics unit 27 is shown, which can be used in the projection exposure device 1, replacing the one according to Figure 2 The projection optical unit 10 in the embodiment. (As previously mentioned) Figures 1 to 9 ,in particular Figures 1 to 3 The components and functions explained are denoted by the same reference numerals in the accompanying drawings and will not be discussed in detail.

[0184] The basic structure of the projection optical unit 27 corresponds to the basic structure of the projection optical unit 10.

[0185] In the case of projection optical unit 27, the two GI mirror pairs (M2 and M3 on one hand, and M5 and M6 on the other hand) have a deflection effect that subtracts from each other in each case.

[0186] The last GI mirror M6 and the last mirror M8 are spatially adjacent, which determines the image-side numerical aperture of the projection optical unit 27.

[0187] In the projection optical unit 27, the intermediate image ZB is again located in the imaging beam path between the mirrors M4 and M5 in a caustic form.

[0188] The projection optical unit 27 has an accessible entrance pupil on the imaging beam path upstream of the object field 5.

[0189] In the projection optics unit 27, the exit pupil is located in the reflection area at the reflector M7. An aperture stop can then be configured on this reflector, and internal blocking of the projection optics unit 27 can be specified if necessary.

[0190] In the case of projection optical unit 27, the distance between object plane 6 and image plane 12 is 1650 mm.

[0191] The overall transmission rate of the projection optical unit 27 is 10.4%.

[0192] The tables below summarize the parameters and optical design of the projection optics unit 27. Structurally, these tables are integrated with the preceding text. Figure 2 The table provided corresponds to this explanation.

[0193] Table 6 lists the aperture stop AS of the projection optics unit 27 configured in the region of the mirror M7. This aperture stop is defined by a polygon, and its x and y values ​​are listed in Table 6.

[0194]

[0195]

[0196] Figure 10 Table 1

[0197] M1 M2 M3 M4 Maximum angle of incidence [°] 17.2 85.4 84.9 20.1 Minimum angle of incidence [°] 12.7 73.2 80.1 16.4 The extent of the reflective surface in the x-direction [mm] 569.6 586.8 605.5 626.2 The range of the reflective surface in the y-direction [mm] 212.3 262.7 260.6 41.0 Maximum reflector diameter [mm] 569.6 586.9 606.1 626.4

[0198] Figure 10 Table 2a

[0199] M5 M6 M7 M8 Maximum angle of incidence [°] 85.7 81.7 24.6 12.3 Minimum angle of incidence [°] 81.2 76.2 3.6 5.1 The extent of the reflective surface in the x-direction [mm] 502.4 456.2 337.8 418.6 The range of the reflective surface in the y-direction [mm] 355.4 215.9 91.9 371.7 Maximum reflector diameter [mm] 505.8 456.3 337.8 418.6

[0200] Figure 10 Table 2b

[0201]

[0202]

[0203] Figure 10 Table 3a

[0204] The aperture AS is mounted on the mirror M7. The position and tilt of the aperture surface of the aperture AS take into account the sag of the mirror M7 at the edge of its aperture.

[0205] Inclination about the x-axis (in degrees) Inclination about the y-axis (in degrees) Inclination about the z-axis (in degrees) field 0 0 0 M1 8.34 180 0 M2 -55.94 0 0 M3 -52.45 180 0 M4 11.58 0 0 M5 -89.79 180 0 M6 265.86 0 0 Aperture (AS) -0.28 180 0 M7 -0.50 180 0 M8 7.09 0 0 Image field 0 0 0

[0206] Figure 10 Table 3b

[0207]

[0208]

[0209]

[0210]

[0211]

[0212]

[0213]

[0214]

[0215]

[0216]

[0217]

[0218]

[0219]

[0220]

[0221]

[0222]

[0223]

[0224]

[0225]

[0226]

[0227]

[0228] Figure 10 Table 4

[0229] reflector Reflectance [%) M1 65.6 M2 83.6 M3 88.8 M4 64.3 M5 90.7 M6 84.0 M7 65.1 M8 67.2 Overall transmission rate 10.4

[0230] Figure 10 Table 5

[0231]

[0232]

[0233] Figure 10 Table 6

[0234] Without considering polishing overflow, the overall reflector surface area of ​​the projection optical unit 27 is 0.76 μm. 2 When considering polishing overflow, the overall mirror surface area is 0.97m. 2 .

[0235] Figure 12 and 13 Another embodiment of the projection optics unit or imaging optics unit 28 is shown, which can be used in the projection exposure apparatus 1, instead of according to Figure 2 The projection optical unit 10 in the embodiment. (As previously mentioned) Figures 1 to 11 ,in particular Figures 1 to 3 The components and functions explained are denoted by the same reference numerals in the accompanying drawings and will not be discussed in detail.

[0236] In terms of basic structure, according to Figure 12 and Figure 13 The projection optical unit 28 and according to Figure 10 The projection optical unit 27 is similar. The essential difference is that in the projection optical unit 28, an intermediate image also exists on a plane perpendicular to the meridional plane, which can be seen from... Figure 13 As seen in the view, the intermediate image ZB is located on the imaging beam path between mirrors M4 and M5, and its position is determined according to... Figure 12 It lies on the meridian plane and also on the plane perpendicular to it.

[0237] The projection optics unit 28 is telecentric on the object side. Similarly, the exit pupil is located in the reflection region of the imaging beam path near mirror M7. An aperture stop and a selective shading stop may also be partially attached here and in the imaging beam path between mirrors M7 and M8. The above description of the projection optics unit 10 also applies here.

[0238] In the case of projection optical unit 28, the distance between object plane 6 and image plane 12 is 2151 mm.

[0239] The tables below summarize the parameters and optical design of the projection optics unit 28. Structurally, these tables are integrated with the above text. Figure 2 The table provided corresponds to this explanation.

[0240]

[0241] Figure 12Table 1

[0242]

[0243] Figure 12 Table 2a

[0244] M5 M6 M7 M8 Maximum angle of incidence [°] 85.3 82.4 23.2 15.4 Minimum angle of incidence [°] 80.1 78.6 4.3 10.1 The extent of the reflective surface in the x-direction [mm] 175.2 247.6 384.8 475.0 The range of the reflective surface in the y-direction [mm] 470.4 447.9 76.5 428.5 Maximum reflector diameter [mm] 624.7 505.0 385.2 476.2

[0245] Figure 12 Table 2b

[0246]

[0247]

[0248] Figure 12 Table 3a

[0249]

[0250] Figure 12 Table 3b

[0251]

[0252]

[0253]

[0254]

[0255]

[0256]

[0257]

[0258]

[0259]

[0260]

[0261]

[0262]

[0263]

[0264]

[0265]

[0266]

[0267]

[0268]

[0269]

[0270]

[0271]

[0272]

[0273] Figure 12 Table 4

[0274] reflector reflectivity M1 65.9 M2 80.9 M3 87.6 M4 65.2 M5 89.7 M6 86.7 M7 65.3 M8 66.3 Overall transmission rate 10.2

[0275] Figure 12 Table 5

[0276] Excluding polishing overflow, the overall reflective surface area of ​​the projection optical unit 28 is 0.69 μm. 2 .

[0277] Figure 14 and Figure 15 Another embodiment of the projection optics unit or imaging optics unit 29 is shown, which can be used in the projection exposure apparatus 1, instead of according to Figure 2 The projection optical unit 10 in the embodiment. (As previously mentioned) Figures 1 to 13 ,in particular Figures 1 to 3 The components and functions explained are denoted by the same reference numerals in the accompanying drawings and will not be discussed in detail.

[0278] In terms of basic structure, according to Figure 14 and Figure 15 The projection optical unit 29 and according to Figure 2 and Figure 3 The projection optics unit 29 is similar to that of the projection optics unit 10. The essential difference is that exactly one GI mirror (i.e., mirror M2) exists in the projection optics unit 29, replacing the two consecutively arranged GI mirrors M2 and M3. Basically, this GI mirror M2 of the projection optics unit 29 performs the same function as the GI mirrors M2 and M3 of the projection optics unit 10.

[0279] The projection optical unit 29 has exactly three GI reflectors, namely reflectors M2, M4, and M5.

[0280] M5. The projection optical unit 29 has exactly seven mirrors M1 to M7 in the beam path between the object field 5 and the image field 11.

[0281] The sequence of incident angles of the first three mirrors M1, M2, and M3 in the beam path of the projection optical unit 29 is NI(M1), GI(M2), and NI(M3).

[0282] The sequence of incident angles of the seven mirrors M1 to M7 of the projection optical unit 29 in the beam path between object field 5 and image field 11 is NI, GI, NI, GI, GI, NI, NI.

[0283] The object field 5 and the image field 11 are rectangular in the projection optical unit 29.

[0284] The intermediate image ZB in the yz plane (meridian plane) is located in the reflection region of the imaging light 16 at the mirror M5.

[0285] There is no intermediate image between the object field 5 and the image field 11 in the xy plane perpendicular to it. In the case of the projection optical unit 29, the image plane 12 is the first field plane downstream of the object plane 6 of the imaging optical unit 29 in the imaging beam path in the imaging light plane containing the image field extension direction x. Image flipping occurs in this imaging light plane. Conversely, since an intermediate image ZB appears here, there is no image flipping in the meridional imaging plane.

[0286] The average wavefront aberration in the projection optical unit 29 is approximately 13mλ.

[0287] The overall transmission rate of the projection optical unit 29 is 11.1%. In the case of the projection optical unit 29, the overall reflective surface area without polished overflow is 0.83 μm. 2 The overall installation height (i.e., the distance between the object plane and the image plane) is 2255mm. The object-image offset is d. OIS It is 899 mm.

[0288] In the projection optics unit 29, an aperture stop or a light-blocking stop is positioned in the imaging beam path between mirrors M5 and M6. This stop is located near mirror M6 and is passed through several times by the imaging light. The stop can be designed to be subdivided into multiple partial stops.

[0289] The tables below summarize the parameters and optical design of the projection optics unit 29. Structurally, these tables are integrated with the above text. Figure 2 The table provided corresponds to this explanation.

[0290]

[0291]

[0292] Figure 14 Table 1

[0293]

[0294] Figure 14 Table 2a

[0295]

[0296]

[0297] Figure 14 Table 2b

[0298] x-distance [mm] y-distance [mm] z-distance [mm] field 0.00 898.94 2254.93 M1 0.00 772.80 1054.80 M2 0.00 300.63 1705.60 M3 0.00 46.09 1858.33 M4 0.00 320.75 1184.89 M5 0.00 325.72 798.74 Aperture stop 0.00 176.62 176.88 M6 0.00 161.32 113.07 M7 0.00 0.00 653.23 Image field 0.00 0.00 0.00

[0299] Figure 14 Table 3a

[0300]

[0301]

[0302] Figure 14 Table 3b

[0303]

[0304]

[0305]

[0306] Figure 14 Table 4a

[0307]

[0308]

[0309]

[0310]

[0311] Figure 14 Table 4b

[0312]

[0313]

[0314]

[0315]

[0316]

[0317] Figure 14Table 4c

[0318] Figure 16 and Figure 17 Another embodiment of the projection optics unit or imaging optics unit 30 is shown, which can be used in the projection exposure apparatus 1, instead of according to Figure 2 The projection optical unit 10 in the embodiment. (As previously mentioned) Figures 1 to 15 ,in particular Figures 1 to 3 The components and functions explained are denoted by the same reference numerals in the accompanying drawings and will not be discussed in detail.

[0319] In terms of basic structure, according to Figure 16 and Figure 17 The projection optical unit 30 and according to Figure 10 The projection optics unit 27 is similar. The essential difference is that now exactly one GI mirror (i.e., GI mirror M2) is used in the projection optics unit 30, replacing the two GI mirrors M2 and M3 in the projection optics unit 27. Figure 16 In the meridional beam path shown, this GI reflector M2 has a counterclockwise deflection effect.

[0320] The reflectors M1 and M3 to M7 of the projection optical unit 30 correspond to the reflectors M1 and M4 to M8 of the projection optical unit 27 in terms of their deflection effect.

[0321] Just like the projection optical unit 29, according to Figure 16 and 17 The projection optical unit 30 also has the incident angle sequence NI, GI, NI of the first three mirrors M1 to M3 in the imaging beam path between the object field 5 and the image field 11.

[0322] Similarly, 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 in the beam path between the object field 5 and the image field 11. Like the projection optical unit 29, the projection optical unit 30 also has an incident angle sequence of NI, GI, NI, GI, GI, NI, NI.

[0323] The object field 5 and the image field 11 are rectangular in the projection optical unit 30.

[0324] Like projection optical unit 27, projection optical unit 30 also has a meridional intermediate image ZB existing in the form of a caustic image, and does not have an intermediate image in the plane perpendicular to it. Figure 17 The meridian is like ZB ( Figure 16 The region located in the imaging beam path of the projection optical unit 30 between mirrors M3 and M4.

[0325] In the case of projection optical unit 30, the aperture or light-blocking stop is located near the penultimate reflector M6. The average wavefront aberration rms is approximately 8mλ. The overall transmittance of projection optical unit 30 is approximately 11.2%. In the case of projection optical unit 30, the overall reflector surface area without polishing overflow is 0.89m. 2 The distance between object plane 6 and image plane 12 is 2278 mm. The object-image offset d of projection optical unit 30... OIS It is 987 mm.

[0326] The tables below summarize the parameters and optical design of the projection optics unit 30. Structurally, these tables are integrated with the above text. Figure 2 The table provided corresponds to this explanation.

[0327]

[0328]

[0329] Figure 16 Table 1

[0330]

[0331] Figure 16 Table 2a

[0332] M5 M6 M7 Maximum angle of incidence [°] 87.4 25.7 12.9 Minimum angle of incidence [°] 79.0 3.8 7.0 The extent of the reflective surface in the x-direction [mm] 515.9 416.4 494.1 The range of the reflective surface in the y-direction [mm] 171.5 108.5 446.2 Maximum reflector diameter [mm] 516.9 416.4 495.2 Average transfer rate [%) 86.0 64.6 64.5 Minimum transfer rate [%) 85.4 64.5 64.8 Maximum transfer rate [%) 86.7 64.8 0.0

[0333] Figure 16 Table 2b

[0334]

[0335]

[0336] Figure 16 Table 3a

[0337]

[0338] Figure 16 Table 3b

[0339]

[0340]

[0341]

[0342]

[0343] Figure 16 Table 4a

[0344]

[0345]

[0346]

[0347]

[0348] Figure 16 Table 4b

[0349]

[0350]

[0351]

[0352]

[0353] Figure 16 Table 4c

[0354] Figure 18 and Figure 19 Another embodiment of the projection optics unit or imaging optics unit 31 is shown, which can be used in the projection exposure apparatus 1, instead of according to Figure 2 The projection optical unit 10 in the embodiment. (As previously mentioned) Figures 1 to 17 ,in particular Figures 1 to 3 The components and functions explained are denoted by the same reference numerals in the accompanying drawings and will not be discussed in detail.

[0355] In terms of basic structure, according to Figure 18 and Figure 19 The projection optical unit 31 and according to Figure 16 and Figure 17 The projection optical unit 31 is similar to the projection optical unit 30. However, the deflection effects of the three GI mirrors M2, M4, and M5 in the projection optical unit 31 are exactly the opposite of those in the projection optical unit 30. In the case of the projection optical unit 30, based on... Figure 16 In the meridional section, reflector M2 has a counterclockwise deflection effect, reflector M4 has a clockwise deflection effect, and reflector M5 again has a counterclockwise deflection effect.

[0356] In the case of projection optical unit 31, according to Figure 18 In the meridional section, reflector M2 has a clockwise deflection effect, reflector M4 has a counterclockwise deflection effect, and reflector M5 again has a clockwise deflection effect.

[0357] The object field 5 and the image field 11 are rectangular in the projection optical unit 31.

[0358] The projection optical unit 31 has a meridional intermediate image ZB in the imaging beam path between the two GI reflectors M4 and M5. In the plane perpendicular to it ( Figure 19 There is no intermediate image in the imaging beam path between object field 5 and image field 11. In the case of projection optics unit 31, the aperture or shading stop is located near the penultimate mirror M6. The average wavefront aberration rms is approximately 10.4 mλ. The overall transmission rate of projection optics unit 31 is approximately 11%. In the case of projection optics unit 31, the overall mirror surface area without polished overflow is 0.74 m. 2 The distance between object plane 6 and image plane 12 is 1963 mm. Object-image offset d OIS It is 1100 mm.

[0359] The tables below summarize the parameters and optical design of the projection optics unit 31. Structurally, these tables are integrated with the above text. Figure 2 The table provided corresponds to this explanation.

[0360] Wavelength [nm] 13.5 Image-side numerical aperture 0.33 Image field size in the x and y directions [mm × mm] 52×1.7 Circumferential radius [mm] - βx 2 βy 4 Principal ray angle [°] 6 Light Spread 9.63 Mean wavefront aberration RMS[mλ] 10.4 Overall transfer rate [%) 10.98 Position of the entrance pupil (x) -1598.88 Position of the entrance pupil (y) 1711.44 Object-image offset in the y-direction [mm] 1099.99 Distance between M7 and the image plane [mm] 101 Distance between object plane and image plane 1963.03 Inclination between the object plane and the image plane [°] 0 Installation space cube [mm×mm×mm] 626×1305×1512

[0361] Figure 18 Table 1

[0362]

[0363] Figure 18 Table 2a

[0364]

[0365] Figure 18 Table 2b

[0366] x-distance [mm] y-distance [mm] z-distance [mm] field 0.00 986.59 2278.76 M1 0.00 865.53 1126.98 M2 0.00 677.89 1536.42 M3 0.00 688.20 1924.65 M4 0.00 329.52 1114.62 M5 0.00 305.23 616.02 M6 0.00 107.52 112.78 Aperture stop 0.00 105.34 107.23 M7 0.00 0.00 690.22 Image field 0.00 0.00 0.00

[0367] Figure 18 Table 3a

[0368] Figure 18 Table 3b

[0369]

[0370]

[0371]

[0372] Figure 18 Table 4a

[0373]

[0374]

[0375] Figure 18 Table 4b

[0376]

[0377]

[0378]

[0379]

[0380] Figure 18 Table 4c

[0381] Depending on the embodiment of the aforementioned projection optics unit, different numbers of NI mirrors and / or GI mirrors may also be used, such as fewer or more than four GI mirrors, for example, exactly one GI mirror, exactly two GI mirrors, or exactly three GI mirrors. Fewer or more than four NI mirrors are also possible, for example, two, three, or five NI mirrors.

[0382] To generate microstructured or nanostructured components, the projection exposure apparatus 1 is used as follows: First, a reflective mask 7 or a mask master and a substrate or wafer 13 are provided. Next, with the assistance of the projection exposure apparatus 1, the structure on the mask master 7 is projected onto the photosensitive layer of the wafer 13. Then, by developing the photosensitive layer, microstructures or nanostructures are generated on the wafer 13, thereby generating microstructured components.

Claims

1. An EUV imaging optical unit (10; 27; 28; 29; 30, 31) for imaging an object field (5) onto an image field (11), It has multiple mirrors (M1 to M8) for guiding EUV imaging light (16) with wavelengths shorter than 30 nm from the object field (5) toward the image field (11) along the imaging beam path. The multiple mirrors (M1 to M8) have an overall transmittance of greater than 5% for the EUV imaging light (16). in, The image field (11) of the imaging optical unit (10; 27; 28; 29; 30, 31) has a maximum range of more than 50 mm in the image plane (6).

2. The imaging EUV optical unit as described in claim 1, characterized in that... Less than 1.5m 2 The entire surface of the reflective mirror.

3. The imaging EUV optical unit as described in claim 1 or 2, characterized in that... Different imaging scales (β) in two imaging light planes (xz, yz) containing two perpendicular image field extension directions (x, y) x ,β y ).

4. The imaging EUV optical unit as described in any one of claims 1 to 3, characterized in that... The displacement direction imaging ratio (β) in one of the two imaging planes (yz) containing the object displacement direction (y) of the object to be imaged (7). y Its absolute value is the lateral dimension imaging scale (β) in one of the two imaging planes (xz) perpendicular to the object's displacement direction (y). x At least 1.1 times that of ).

5. The imaging EUV optical unit as described in any one of claims 1 to 4, characterized in that... At least one intermediate image (ZB) in at least one imaging light plane (yz; xz, yz) containing the image field extension direction (x, y).

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

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

8. The imaging EUV optical unit as described in any one of claims 1 to 7, characterized in that... The image field (11) has a double-arched shape.

9. The imaging EUV optical unit as described in any one of claims 1 to 8, characterized in that... At least four NI mirrors (M1, M4, M7, M8; M1, M3, M6, M7).

10. The imaging EUV optical unit as described in any one of claims 1 to 9, characterized in that... At least four GI mirrors (M2, M3, M5, M6).

11. The imaging EUV optical unit as claimed in any one of claims 1 to 10, characterized in that... At least one pair of adjacent GI mirrors (M2, M3; M5, M6; M4, M5) in the beam path.

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

13. The imaging EUV optical unit as described in any one of claims 1 to 12, characterized in that... No more than three GI mirrors (M2, M4, M5) and / or no more than seven mirrors (M1 to M7) are included in the imaging beam path.

14. An optical system, It has an illumination optics unit (4) for illuminating the object field (5) using imaging light (16), It has an imaging optical unit (10) as described in any one of claims 1 to 13.

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

16. A method for manufacturing a structured component, comprising the following method steps: Provides a mask master (7) and a chip (13), The structure on the mask master (7) is projected onto the photosensitive layer of the wafer (13) using the projection exposure apparatus as described in claim 15. Microstructures and / or nanostructures are generated on the wafer (13).

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

Images