Method for operating microlithography projection exposure apparatus, microlithography mask, and projection exposure apparatus

Abstract

To provide a method for operating a microlithography projection exposure apparatus (1) which brings about at least partially the following for compensation of image deviation which occurs due to a degree of dipole illumination (300), and finally causes undesired loss (M3D) effect of image forming contrast, for example.SOLUTION: A method brings about a field-dependent illumination in which different field regions of an objective surface (6) are illuminated by different illumination settings, and generation of field-dependent image deviation in image-forming of the objective surface onto an image surface (12). Herein, the interaction between field-dependent illumination and the field-dependent image deviation can reduce a loss as the whole image forming contrast. The field-dependent illumination can be carried out by an MEMS facet mirror (20) in an illumination device (2), for example, and the field-dependent image deviation can be carried out by horizontal and / or perpendicular mask distortion combined with adapted feed change, for example.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] This application claims priority to German patent application No. 102023127297.7, filed on October 6, 2023, the contents of which are incorporated herein by reference.

[0002] The present invention relates to a method for operating a microlithographic projection exposure apparatus, to a microlithographic mask and to a microlithographic projection exposure apparatus. [Background technology]

[0003] Microlithography is used to manufacture microstructured electronic components. The microlithography process is carried out in what is called a projection exposure apparatus, which has an illumination device and a projection lens. Here, the image of a mask (=reticle), illuminated by an illumination device, is projected using the projection lens onto a substrate (e.g. a silicon wafer) that is coated with a light-sensitive layer (photoresist) and placed in the image plane of the projection lens, in order to transfer the mask structure into a photosensitive coating of the substrate.

[0004] In projection lenses designed for the EUV range, e.g. at wavelengths of about 13 nm, about 11 nm, about 7 nm or about 4 nm, mirrors are used as optical components for the imaging process, since suitable light-transmitting refractive materials are not available.

[0005] One problem that arises in practice is that three-dimensional mask effects (also called mask 3D effects or "M3D" for short) result in wavefront tilt and image shift that depend on the illumination angle or direction of illumination on the mask. For large-area illumination (e.g. dipole illumination), this results in image smearing and therefore reduced contrast in the image formed in the wafer plane, which can cause serious problems with the performance and quality of the lithography process.

[0006] Known approaches to overcome this problem include, in particular, new mask materials, new illumination modes, and the use of what is called split dipole illumination, in which an exposure or scanning operation is split into two exposure operations with different illumination poles. However, the known approaches of split dipole illumination described above are accompanied by an undesirable decrease in the throughput achieved in the lithographic process and / or the occurrence of additional image errors (in particular overlay errors), and the remaining measures described above only solve this problem to an unsatisfactory extent.

[0007] The problem of misalignment in the case of dipole illumination in the prior art is explained in more detail below with reference to FIG.

[0008] Figure 3 (corresponding to figure 4 of WO 2020 / 221556) shows a schematic of the illumination pupil of an EUV projection exposure apparatus using dipole illumination, with the two poles shown as light and dark only for clarity. As can be seen, due to the distance between the poles and the distance from the optical axis, an image shift of approximately -3 nm (in this example) for one pole and approximately +3 nm for the other pole occurs, i.e. a total shift of approximately 6 nm.

[0009] The resulting overlay image in the image representation on the wafer plane is shown (also diagrammatically) in Figure 2. The incoherent overlap of two monopolar images (respectively the continuous and dashed curves) results in a dotted integrated curve.

[0010] This integration curve shows that the intensity at the periphery does not return completely to zero, but only to a value of about 0.15, and the maximum is not 1.0 but somewhat less than 0.9, resulting in a reduction of the 100% contrast ratio to about 75%, which can result in significant performance and quality penalties as discussed above.

[0011] In contrast, Figure 1 shows a situation where the present invention reduces the M3D effect, and as a result, as can be seen, can significantly improve the contrast ratio, in this example by up to 90%, as will be explained in more detail below.

[0012] With regard to the prior art, reference is made, purely by way of example, to the aforementioned International Patent Application No. 2020 / 221556 and German Patent Publication No. 102014217611. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] International Patent Application No. 2020 / 221556 [Patent Document 2] German Patent Publication No. 102014217611 Summary of the Invention

[0014] The present invention aims to provide a method for operating a microlithography projection exposure apparatus, a microlithography mask and a microlithography projection exposure apparatus, by which improved compensation of aberrations caused by imaged mask structures is possible.

[0015] This object is achieved by means of the features of the independent claims.

[0016] Advantageous refinements of the invention are set forth in the dependent claims.

[0017] The method according to the invention functions for operating a microlithography projection exposure apparatus having an illumination device and a projection lens, where the illumination device illuminates a mask located in the object plane of the projection lens, and the projection lens images structures on this mask onto a photosensitive layer located in the image plane of the projection lens, and in a scanning motion, the respective illuminated areas of the mask are changed.

[0018] The illumination device may in particular have a spatially extended illumination field with two or more illumination poles spaced apart in the horizontal direction, i.e., in the x-direction, and / or in the vertical direction, i.e., in the y-direction, resulting in, as described above, an image shift on the photosensitive layer and thus an undesirable loss of imaging contrast due to the M3D effect.

[0019] The method according to the invention comprises the steps of: - the illumination of the mask is performed as field-dependent illumination, in which different field areas of the object plane are illuminated by different illumination settings, characterised in that, when the object plane is imaged onto the image plane, a field-dependent image shift is produced, in which different field areas of the object plane are converted into different image shifts.

[0020] Here, illumination setting is understood to mean the intensity distribution in the pupil plane of an illumination device.

[0021] According to one embodiment, the interaction of the field-dependent illumination with the field-dependent image shift results in an increased imaging contrast upon imaging onto the image plane compared to imaging without the field-dependent image shift.

[0022] In other words, when a field-dependent image shift is caused, the field-dependent illumination modifies the illuminance distribution in a field-dependent manner so that the interference shift can be compensated for and correction can be brought about, thereby reducing the overall image shift of the final result and therefore increasing the imaging contrast.

[0023] According to one embodiment, the mask is illuminated via an elongated scan slit, in particular in the shape of a circular arc, the scan direction running transversely to the scan slit, and during the scanning movement several field areas of the object plane are illuminated in each case with different illumination settings, where in particular at least two field areas of the object plane can overlap one another.

[0024] According to one embodiment, the field dependent image shift is caused depending on the lateral position of the radiation incident on the scan slit when imaged onto the image plane.

[0025] In other words, in order to produce the desired compensatory shift due to the field-dependent image shift, a lateral degree of freedom relative to the scan slit, i.e., variation in the y direction (direction of scanning), is used to image the individual poles separately by field-dependent illumination more or less in this lateral direction.

[0026] According to one embodiment, field-dependent illumination of the mask is performed via a faceted mirror arrangement or a mirror array arrangement having a microelectromechanical system (MEMS), whereby radiation from a first illumination electrode provides illumination primarily in the lower region of the scan slit and radiation from a second illumination electrode provides illumination primarily in the upper region of the scan slit.

[0027] In one refinement, the offset compensation according to the invention can be carried out particularly effectively if a separating dark field is provided between the illumination in the upper region of the scan slit and the illumination in the lower region of the scan slit.

[0028] Field-dependent image shift can be induced in embodiments of the present invention via a distortion profile built into the mask structure.

[0029] In particular, the horizontal mask structures and / or the vertical mask structures can each have a specified distortion profile for this purpose, and in this regard, the mask feed and / or the feed of the photosensitive layer are accordingly modified during the scanning operation to compensate for the distortion profile, compared to a nominal mask feed.

[0030] Here, differences arise depending on whether, during illumination of the mask in each case, the spaced apart illumination poles are arranged perpendicularly or horizontally to the scan slit main direction, i.e. - in order to reduce the image shift in the case of horizontally spaced illumination poles (preferably for imaging vertically oriented structures), the mask structures preferably have to be distorted in the horizontal direction, which can be compensated for by an additional horizontal displacement of the mask and / or of the photosensitive layer, - In order to reduce image deviations in the case of vertically spaced illumination poles (to image mainly horizontally oriented structures), the mask structures preferably need to be distorted vertically, which can be compensated for by a feed speed between the mask and the photosensitive layer that deviates from the nominal feed speed.

[0031] Oblique placement or orientation of the illumination poles with respect to the scan slit main direction may be considered as well, implying a combination of the two measures mentioned above.

[0032] The proposed mask distortion tends to cause a degradation of the imaging quality of the dipole single image, but this effect becomes less noticeable when considering the misalignment compensation achievable according to the invention, i.e. an optimum compromise, as detailed below.

[0033] Although the present invention as part of this disclosure is primarily described using a dipole illuminator, the application of the present invention should not be limited to dipole illuminators, but may be used, possibly with appropriate modifications, for misalignment compensation in other illumination sources that are not approximately in the form of discrete points (e.g., approximately line-shaped illumination sources, or compound illumination pupils optimized by SMO ("source-mask optimization")), and possibly for n-pole illumination, where n>2, e.g., quadrupole illumination.

[0034] For possible illumination settings, see, for example, the published literature L. Wischmeier et al.: "High-NA EUV lithography optics becomes reality," Proc. SPIE 11323, Extreme Ultraviolet (EUV) Lithography XI, 1132308 (23 March 2020); doi: 10.1117 / 12.2543308, see Figures 3b and 3c therein.

[0035] In a preferred embodiment of the present invention, the above-mentioned distortions for a horizontally extending arc-shaped scan slit with laterally varying field-dependent illumination distortions can be implemented in a first approximation according to one or more of the following transformations: - distortion of vertical mask structures according to (x,y)->(x+dfx*(y-rfs(x)),y), and / or - distortion of the horizontal mask structure according to (x,y)->(x,y+dfy*(y-rfs(x))), Where: rfs(x) represents the profile of the y-component of the specified zero distortion line of the scan slit depending on the x-position, dfx, dfy represent the specified vertical or horizontal distortion coefficients, and both coefficients may be the same.

[0036] In a further embodiment, the field-dependent image shift can be implemented (alternatively or possibly additionally) by an operation performed during a scanning motion in the projection lens.

[0037] Also proposed as part of the present invention is a microlithography mask, designed for use in the manner described above, i.e. specifically designed with intentional distortions to produce field-dependent image shift, or at least proposed as an important component of the present invention (in short, the entire field-dependent image shift generally further includes compensatory adaptation in the mask / wafer feed).

[0038] Also provided as part of the invention is a projection exposure apparatus, which is designed to carry out the method described above.

[0039] Further developments of the invention become apparent from the description and the dependent claims.

[0040] The present invention will now be described in detail based on exemplary embodiments shown in the accompanying drawings. [Brief description of the drawings]

[0041] [Figure 1] 1 shows spatially dependent intensity diagrams to explain the imaging quality on a wafer exposed to dipole illumination, and illustrates the intensity profile using misalignment compensation according to the present invention. [Diagram 2] FIG. 1 shows spatially dependent intensity diagrams to illustrate the imaging quality on a wafer exposed to dipole illumination, with the profile without this misalignment compensation shown for comparison. [Diagram 3] FIG. 2 is a schematic diagram illustrating the formation of imaging deviation in the case of symmetric dipole illumination. [Figure 4] FIG. 1 is a schematic diagram showing the division of dipole illumination into upper and lower fields of view according to horizontal dipole orientation. [Diagram 5] FIG. 13 is a schematic diagram illustrating horizontal mask distortion for distortion compensation due to horizontal dipole orientation. [Figure 6] FIG. 13 is a schematic diagram illustrating the intensity distribution in the scan direction resulting from horizontal mask distortion. [Figure 7a-7b] FIG. 13 is a schematic diagram to explain the effect of horizontal mask distortion written into a mask structure. [Figure 8] FIG. 13 is a schematic diagram showing the division of dipole illumination into upper and lower fields of view with a vertical dipole orientation (for imaging primarily horizontal structures). [Figure 9] FIG. 13 is a schematic diagram illustrating horizontal mask distortion for distortion compensation due to vertical dipole orientation. [Figure 10] FIG. 13 is a schematic diagram illustrating the intensity distribution in the scan direction resulting from vertical mask distortion. [Figure 11a-11b] FIG. 1 is a schematic diagram illustrating vertical mask distortion written into a mask structure. [Figure 12] FIG. 13 illustrates the achievable contrast ratio as a function of the distortion coefficient. [Figure 13] FIG. 1 is a schematic diagram illustrating a MEMS facet mirror configuration for implementing field-dependent illumination. [Figure 14] FIG. 13 is a schematic diagram showing an embodiment with a narrower field split with a separate dark field disposed therebetween. [Figure 15] FIG. 15 shows the resulting intensity distribution of the intensity distribution of FIG. 14. [Figure 16] FIG. 1 is a schematic diagram showing an intensity distribution without deviation. [Figure 17] FIG. 17 is a schematic showing the intensity distribution in the scan direction with a narrower field split and a distortion factor of 4 nm / mm (FIG. 17) compared to the intensity distribution without any shift (FIG. 16). [Figure 18] FIG. 1 shows a schematic diagram of a projection exposure apparatus designed for operation in the EUV range. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] The embodiments described below have in common that, in order to compensate for three-dimensional mask effects and the associated undesirable loss of contrast, during operation of the microlithography projection exposure apparatus, field-dependent illumination during the scanning operation is combined with an intentionally induced image shift, which is realized in different ways depending on the embodiment.

[0043] 1 to 3 show schematic diagrams for illustrating the concepts according to the invention already described in more detail in the overview section.

[0044] An imaging misalignment between two dipole illumination sources 301, 302 of a dipole generally designated 300 shown in FIG. 3, in this example about 6 nm, will result in a contrast ratio in the incoherent overlap imaging between the left pole 200 and the right pole 201 on the wafer, totaling 202, dropping to about 75%, according to FIG. 2, with a corresponding penalty to the performance and quality of the overall lithography process.

[0045] With misalignment compensation according to the present invention, it is possible to achieve an improved contrast ratio (see integrated intensity 102 in FIG. 1 ) of about 93% in this example by reducing the misalignment between the left pole 100 and the right pole 101 according to FIG. 1 .

[0046] However, the misalignment compensation measures described in more detail below tend to have a detrimental effect on the contrast ratio of the individual pole imaging, as can be seen by comparing curves 100, 101 with 200, 201. The individual curves 100, 101 are slightly flatter than curves 200, 201, i.e. the "individual" contrast ratio drops to about 95% compared to Figure 2, which in this example still represents a significant contrast improvement of integrated intensity 102 due to the reduced misalignment.

[0047] Implementing view-dependent lighting In order to achieve the desired misalignment compensation, it is first necessary to generate a field-dependent irradiance distribution in which different field regions of the object plane are illuminated with different illumination settings, as a result of which radiation from individual illumination poles is converted into different illumination distribution patterns in a field-dependent or pole-dependent manner.

[0048] This can be achieved by a MEMS (microelectromechanical system) configuration with a number of individually actuable mirrors in the lighting device, as shown in Figure 13, where different orientations of the mirrors (not shown to scale) are shown in different grey scales in the right hand portion of Figure 13.

[0049] Such a MEMS facet mirror can be used within an illumination device and as a field mirror 20 in a microlithography projection exposure apparatus, which is described in more detail below with reference to FIG.

[0050] The use of a variably actuable mirror within the context of the present invention, in combination with the components detailed below, has the added advantage that the misalignment compensation can be varied or optimized or optionally deactivated, i.e. an arrangement according to the present invention can be operated with misalignment compensation "traditionally" without significant physical modifications.

[0051] The mirror facet tilt pattern shown in FIG. 13 is substantially static throughout the operation of the apparatus and produces a pole-dependent separated intensity distribution on the mask, preferably laterally (i.e. in the y direction) to the extent of the scan slit, as described further below.

[0052] In this way, the illumination is split into two regions insofar as the upper part of the scan slit is illuminated exclusively or at least primarily by one illumination pole of the dipole setup, while the lower part of the scan slit is illuminated exclusively or primarily by the respective other illumination pole of the dipole setup, although in principle a peripheral overlap of the regions is possible.

[0053] Alternatively, this effect can be achieved without the use of MEMS by a "fixed" facet mirror (not shown) split into two parts with adjustable tilt of each of the individual parts.

[0054] Yet another possible form for implementing a field-dependent illuminance distribution is described in International Patent Application No. 2016 / 034424, which is intended to be incorporated by reference into this specification in that the partial field-of-view grouping that can be realized by means of a two MEMS mirror arrangement described therein is intentionally used by a ``jigsaw-type'' control of the mirror facets with respect to the pole-dependent intensity distribution desired here.

[0055] Implementing field-dependent image shift Proceeding from a field-dependent illumination, in accordance with the invention a field-dependent image shift is produced, which results in at least partial compensation of the undesired image shift.

[0056] A particularly suitable measure in this connection is the skew distortion of the mask or reticle, which will be explained with reference to FIGS. 4 to 11b together with a corresponding adaptation of the feed speed.

[0057] Here, a distinction is made between vertical mask structures (representation given approximately with reference to the main direction of the scan slit) with a substantially horizontal dipole orientation (see Figures 4 to 7b) and horizontal mask structures (see Figures 8 to 11b) with a substantially vertical dipole orientation.

[0058] For a substantially horizontal dipole (or illumination source of equivalent geometry) as shown in FIG. 4, misalignment compensation between the upper field of view 400 (illuminated by the right dipole, see 402) and the lower field of view 401 (illuminated by the left dipole, see 403) is achieved by a vertically obliquely distorted mask structure as shown in FIG. 5 in combination with a compensatory x-motion of the wafer.

[0059] As a rule, for imaging vertical structures (i.e. vertically oriented lines), preferably horizontally oriented dipoles are used. The deviations of these structures due to the M3D effect extend in the horizontal direction. Therefore, the correction, i.e. the additional mask distortion and the subsequent stage movement, must also take place in the horizontal direction.

[0060] In Figure 5, the distorted structure (not to scale, the distortion is approximately 10 5 The undistorted structures (shown at 2x magnification) are shown as solid lines, and for comparison (as a reference point) the undistorted "straight" structures are shown as dashed lines.

[0061] As can be seen, the distortion is zero in each case along the centerline of the curved scan slit and increases further upwards or downwards with respective opposite signs, specifically following the linear relationship mentioned further above and which is valid to a first approximation below. (x,y)->(x+dfx*(y-rfs(x)),y), where rfx(x) represents the profile of the y-component of the specified zero distortion line of the scanning slit depending on the x-position, dfx represents the specified vertical distortion coefficient, and typical values ​​of dfx range from about 1 nm / mm to about 10 nm / mm.

[0062] In this way, it is then possible to achieve an intensity distribution as shown in FIG. 6, in which a substantially constant integrated intensity (dotted line) over the central region can be achieved.

[0063] In the variant shown in Figures 8-11b, vertical mask distortion structures (i.e. structures acting in the y-direction) as shown in Figures 9 and 11a and 11b are useful in conjunction with substantially vertically oriented dipoles to image horizontal structures.

[0064] Again, no distortion is applied along the centre line, while distortions are applied upwards and downwards in the y direction, with opposite signs in each case, so that the upper and lower regions 801, 802 illuminated by the respective poles (802, 803) are shifted compensatingly, resulting in an intensity distribution according to FIG. 10 that is equivalent to the above case (see FIG. 6).

[0065] In this case, the distortion can be mathematically described to a first approximation as follows: Distortion of the horizontal mask structure, (x,y)->(x,y+dfy*(y-rfs(x))), where where rfs(x) is defined as above, dfy represents the specified horizontal distortion factor (commonly also referred to as sf in an orientation-dependent form).

[0066] To compensate for vertical mask distortion, the mask and wafer stages must also be moved at slightly different feed rates (eg, feed rates that deviate from the nominal feed rate) according to a specified distortion factor.

[0067] Also, in the case of vertical distortion, specific adaptation of the intensity distribution between the upper and lower viewing regions 800, 801 may be required during fine optimization to compensate for the different angles of incidence of the upper and lower polar illumination.

[0068] Although the implementation of the field-dependent image shift has been described above with reference to mask distortion and corresponding adaptation in the mask feed / wafer feed, the invention is explicitly not limited to such an implementation: the compensatory shift can also be realized, for example, by additional optical elements in the beam path.

[0069] Contrast Ratio Optimization The above-mentioned mask distortion itself also causes imaging errors, resulting in contrast ratio degradation. As the distortion coefficient increases aiming at full compensation of the image shift, the individual contrast ratio decreases at the same time, which is why finally, according to the illustration of Fig. 12, the optimization problem has a maximum at a distortion coefficient of about 4 nm / mm in this example embodiment, which does not mean full shift compensation, see the intensity diagram of Fig. 1 explained in the overview part based on a corresponding shift of about sf=4 nm / mm.

[0070] To achieve a further improvement in the contrast ratio, the two illumination fields can be more strictly separated from each other based on narrow bands 1400, 1401 separated by a dark field 1402, as shown diagrammatically in Fig. 14, resulting in a near optimal contrast ratio of about 99% according to Figs. 15-17. See Fig. 17 with a distortion factor sf=4 nm / mm compared to Fig. 16 without misalignment (sf=0).

[0071] However, such a narrow illumination profile may result in a reduction in the effective etendue of the system, which may result in undesirable losses for the light source, which in this case is incoherent.

[0072] FIG. 18 shows a schematic in meridional section of a possible setup of a microlithographic projection exposure apparatus designed for operation in the EUV range.

[0073] According to Fig. 18, a projection exposure apparatus 1 comprises an illumination device 2 and a projection lens 10. In addition to a light source or radiation source 3, an illumination optical unit 4 for illuminating an object field 5 at an object plane 6 is provided. In another embodiment, the light source 3 may be provided as a separate module from the rest of the illumination device. In this case, the illumination device does not comprise a light source 3.

[0074] Here, a reticle 7 arranged in the object field 5 is exposed. The reticle 7 is held by a reticle holder 8. The reticle holder 8 is movable by a reticle movement drive 9, in particular in the scanning direction. For the sake of illustration, a Cartesian xyz coordinate system is shown in FIG. 18. The x direction runs perpendicular to the plane of the drawing. The y direction runs horizontally and the z direction runs vertically. The scanning direction runs in the y direction in FIG. 18. The z direction runs perpendicular to the object plane 6. In an embodiment of the invention, the reticle holder 8 is furthermore movable in the x direction. Also in an embodiment of the invention, a controller is provided for changing the scanning speed.

[0075] The projection lens 10 serves to image the object field 5 into an image field 11 in an image plane 12. The structures on the reticle 7 are imaged onto a photosensitive layer 24 of a wafer 13 that is arranged 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 moved by means of a wafer movement drive 15, in particular in the y direction. The movements of the reticle 7 by means of the reticle movement drive 9 on the one hand and the wafer 13 by means of the wafer movement drive 15 on the other hand can be performed synchronously with respect to one another.

[0076] The radiation source 3 is an EUV radiation source. The radiation source 3 in particular emits EUV radiation, also referred to below as used radiation or illumination radiation. In particular, the used radiation has a wavelength in the range between 5 nm and 30 nm. The radiation source 3 can be, for example, a plasma source, a synchrotron-based radiation source, or a free electron laser (FEL). The illumination radiation 16 emanating from the radiation source 3 is focused by a collector 17 and propagates through an intermediate focus in an intermediate focal plane 18 into the illumination optical unit 4. The illumination optical unit 4 includes a deflection mirror 19, downstream of which in the beam path are arranged a first facet mirror 20 (with a facet 21 shown diagrammatically) and a second facet mirror 22 (with a facet 23 shown diagrammatically). The illustrated illumination optical unit 4 is only an example, and in some embodiments, for example the deflection mirror 19 can be arranged in a different place or not present at all.

[0077] The first facet mirror 20 is also called the field facet mirror and the second facet mirror 2 is also called the pupil facet mirror.

[0078] Within the context of the present invention, provision can in particular be made for the field facet mirror 20 to be designed as a MEMS mirror with individually tiltable facets, by means of which a pole-dependent irradiance distribution can be set.

[0079] The projection lens 10 comprises a number of mirrors Mi (i=1, 2, ...), which are numbered according to their position in the beam path of the projection exposure apparatus 1. In the example shown in Fig. 18, the projection lens 10 comprises six mirrors M1-M6. Alternatives with 4, 5, 7, 8, 10, 12 or a different number of mirrors Mi are also possible. The penultimate mirror M5 and the last mirror M6 each have a through opening for the illumination radiation 16. The projection lens 10 is a double-shielded optical unit. A single-shielded optical unit (only one of the mirrors has a through opening for the illumination radiation) or a completely unshielded optical unit are likewise possible. The projection lens 10 has an image-side numerical aperture which is greater than 0.5, may be greater than 0.6 and may for example be up to 0.85.

[0080] Due to the misalignment compensation possibilities offered by the invention, the mask stack is less constrained in this respect (in terms of absorbers and thicknesses) and can therefore be further optimized, for example in terms of imaging quality, e.g. contrast and reflectivity.

[0081] Horizontally and vertically offset structures can in principle also be combined.

[0082] It is also conceivable to compensate for higher order aberrations, but this may be better achieved by wavefront modification in the projection optical unit.

[0083] Additionally, to achieve finer control of the M3D effect, it is conceivable to split the lighting into more than two regions.

[0084] In addition, while the present invention has been described based on specific embodiments, many variations and alternative embodiments, for example by combining and / or substituting the features of the individual embodiments, will be apparent to those skilled in the art. Accordingly, it goes without saying that such variations and alternative embodiments are also encompassed by the present invention, and the scope of the present invention is limited only within the meaning of the appended claims and their equivalents. [Explanation of symbols]

[0085] 1. Projection exposure equipment 2. Lighting Devices 3 Light source, radiation source 4. Illumination optical unit 5 Objective Field of View 6 Objective surface 7 Reticle 8 Reticle Holder 9 Reticle movement drive 10 Projection lens 11 Image field 12 Image plane 13 Wafer 14 Wafer holder 15 Wafer movement drive 16 Illumination Radiation 17 Concentrator 18 Intermediate focal plane 19 Deflection Mirror 20 First facet mirror, field facet mirror 22 Second facet mirror, pupil facet mirror 24 Photosensitive layer 100 Left Pole Curve 101 Right Pole Curve 102 Accumulative Intensity Curve 200 Left Pole Curve 201 Right Pole Curve 202 Accumulative Intensity Curve 300 Dipole Lighting 301 Dipole Lighting Source 302 Dipole Lighting Source 400 upper field of view 401 Lower Field of View 402 Right Dipole 403 Left Dipole 800 upper viewing area 801 Lower visual field area

Claims

1. A method for operating a microlithography projection exposure apparatus (1) having an illumination device (2) and a projection lens (10), the illumination device (2) illuminating a mask (7) located in an object plane (6) of the projection lens (10), the projection lens (10) imaging structures on this mask (7) onto a photosensitive layer (24) located in an image plane (12) of the projection lens (10), and in a scanning motion the respective illuminated area of ​​the mask is varied, - the illumination of the mask (7) is performed as a field-dependent illumination, in which different field areas of the object plane (6) are illuminated by different illumination settings, When imaging the object plane onto the image plane (12), a field-dependent image shift is generated, in which different field areas of the object plane (6) are converted into different image shifts, A method comprising:

2. 2. The method according to claim 1, characterized in that the interaction of the field-dependent illumination with the field-dependent image shift increases the imaging contrast that occurs during the imaging on the image plane (12) compared to imaging without field-dependent image shift.

3. 3. The method according to claim 1 or 2, characterized in that the mask (7) is illuminated via an elongated scan slit, in particular in the shape of a circular arc, the scan direction extending transversely to the scan slit, and during the scanning movement several field areas of the object plane (6) are illuminated with different illumination settings in each case.

4. 4. The method according to claim 3, characterized in that at least two viewing areas of the object plane (6) overlap each other.

5. 5. The method according to claim 3, wherein the field-dependent image shift is produced in dependence on the lateral position of radiation incident on the scan slit during the imaging onto the image plane (12).

6. 6. The method according to claim 3, wherein the field-dependent illumination of the mask (7) is performed via a facet mirror arrangement or a mirror array arrangement with a microelectromechanical system (MEMS), and radiation from a first illumination pole (301) results in illumination mainly in a lower region of the scan slit and radiation from a second illumination pole (302) results in illumination mainly in an upper region of the scan slit.

7. 7. The method of claim 6, characterized in that a separation dark field (1402) is provided between the illumination in the upper region of the scan slit and the illumination in the lower region of the scan slit.

8. 8. The method according to claim 1, wherein the field-dependent image shift is realized by horizontally extending mask structures of the mask (7) and / or vertically extending mask structures of the mask (7), each having a specified distortion profile, and wherein a mask feed and / or a feed of the photosensitive layer (24) performed during the scanning operation is modified in relation to a nominal mask feed to compensate for the distortion profile.

9. - when illuminating the mask (7) by horizontally spaced illumination poles, the mask structures of the mask (7) are distorted in the horizontal direction, which horizontal distortion is compensated for by an additional horizontal displacement of the mask (7) and the photosensitive layer (24), and / or - during illumination of the mask (7) by vertically spaced illumination poles, the mask structures of the mask (7) are distorted in the vertical direction, this vertical distortion being compensated for by a feed speed between the mask (7) and the photosensitive layer (24) deviating from the nominal feed speed; The method according to claim 8, characterized in that

10. The distortion of the mask structure in a horizontally extending arc-shaped scan slit where the field-dependent illumination distortion varies laterally is expressed by at least the following transformation formula: the distortion of the vertical mask structures according to (x,y)→(x+dfx*(y−rfs(x)),y), and / or the distortion of the horizontal mask structure according to (x,y)→(x,y+dfy*(y−rfs(x))), [0023] Where: rfs(x) represents the profile of the y-component of the designated zero distortion line of the scan slit depending on the x-position; dfx, dfy represent the specified vertical or horizontal distortion coefficients, 10. The method of claim 9, wherein both coefficients may be the same.

11. Method according to any one of the preceding claims, characterized in that the field-dependent image shift is implemented by manipulations performed during the scanning movement in the projection lens (10).

12. A microlithography mask (7), characterized in that it is designed for use in the method according to any one of the preceding claims.

13. A microlithographic projection exposure apparatus (1) designed to carry out the method according to any one of the claims 1 to 11.

Images