Illumination optical unit and method for measuring dependency of intensity of illumination light incident on object field on at least one coordinate of detection object field using such illumination optical unit

Abstract

The invention relates to an illumination optical unit (11) having two facet mirrors (6, 7) for reflecting illumination light (2) from an EUV light source (2). The second facet mirror (7) has a second individual mirror (34) forming a second facet (25), which images a set of individual mirrors (26) of the first facet mirror (6) forming the first facet at least into a partial field of the object field (8) via a partial beam (30) of the illumination light (3). The intensity sensor device (31) is used to measure a dependency of an intensity of the illumination light (3) incident on the object field (8) on at least one detection object field coordinate (x). The intensity sensor arrangement has individual sensor mirrors (21S) of the first facet mirror (6), which are assigned to a plurality of different object field positions (xi) along the detection object field coordinates (x). The individual sensor mirror (21S) is designed to reflect the illumination light (3) to an intensity sensor (32i) of the intensity sensor device (31). The result is an illumination optical unit in which the respective intensity coordinate dependent measurements can be performed accurately and in parallel with the operation of use of the illumination optical unit.

Description

[0001] This patent application claims priority to German patent application DE 10 2023 209 697.8, the contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to an illumination optical unit comprising two faceted mirrors. Furthermore, this invention relates to a method for measuring the dependence of the intensity of illumination light incident on an object field on at least one object field coordinate using such an illumination optical unit. Background Technology

[0003] Illumination optical units of the type mentioned in the introduction are known from DE 10 2015 208 512 A1. Summary of the Invention

[0004] The object of this invention is to develop an illumination optical unit of the type mentioned in the introduction and a method for measuring it, such that the dependence of the intensity of illumination light incident on a field on at least one detected field coordinate can be measured accurately and / or in parallel with the practical or operational use of the illumination optical unit.

[0005] According to the present invention, this objective is achieved by an illumination optical unit having the features specified in claim 1 and by a measurement method having the features specified in claim 6.

[0006] According to the present invention, it has been recognized that in the case of an illumination optical unit comprising two faceted mirrors, particularly in the case of an illumination optical unit in which at least one of the two faceted mirrors is designed to include a large number of individual mirrors in a MEMS reflector, there is great flexibility in allocating the individual mirrors in the two faceted mirrors to guide illumination light within the illumination optical unit. This typically results in certain individual mirrors of the first faceted mirror not being used for projection exposure within the illumination optical unit. In the case of the illumination optical unit according to the present invention, the illumination light incident on these individual mirrors of the first faceted mirror can be used to measure the dependence of the intensity of the illumination light incident on the object field on at least one detected object field coordinate. This utilizes the insight that, due to the arrangement on its first faceted mirror, the individual mirrors in the first faceted mirror that are not used for object field illumination allow conclusions to be drawn about which object field coordinates are used to illuminate the individual mirrors for projection exposure, these individual mirrors being adjacent to these sensor individual mirrors along the detected object field coordinates to be measured. This insight allows for the individual mirrors of each sensor to be assigned to the object field coordinates to be detected, and the dependence of far-field illumination intensity on the first faceted mirror typically varies only slightly depending on the size of the individual mirrors. This results in an intensity sensor device with the aid of the illumination optics unit being able to first accurately measure the dependence of illumination intensity on the object field coordinates to be detected, and secondly, to perform measurements in parallel with the operation of the illumination optics unit.

[0007] By assigning the first facet to the second facet, the illumination setting, i.e., the illumination angle distribution of the object field illumination, can be specifically specified. The illumination intensity distribution on the object field coordinates to be detected may depend on the selected illumination setting, and therefore it may be necessary to monitor the illumination intensity distribution in a setting-related manner and correct it if appropriate.

[0008] Even short-term intensity changes can be identified and corrected if appropriate, as part of continuous monitoring during operation using an intensity sensor device.

[0009] The illumination optical unit can be designed with a field plane mirror and a pupil plane mirror, wherein the second plane mirror is arranged in the region of the pupil plane of the illumination optical unit. Alternatively, the illumination optical unit can also be designed as a specular reflector, wherein the second plane mirror is arranged at a certain distance from the illumination pupil plane.

[0010] Intensity sensor devices can be used, in particular, as field-resolved UNICOM sensors. With an intensity sensor device, corresponding devices for influencing the uniformity of illumination intensity across the field height can then be controlled. Such influencing devices are known from EP 0 952 491 A2, and are also known by the name UNICOM.

[0011] The intensity sensor of the intensity sensor device may correspond to the second facet in terms of its boundary shape and / or its surface area. Light loss due to overexposure of the second facet, i.e., loss of illumination light outside the second facet, is similar in magnitude to light loss due to overexposure of the intensity sensor. Specifically, a design can be implemented in which the sensor signal of the intensity sensor remains proportional to the intensity of the illumination light arriving at the object field, even if light loss in the object field illumination (e.g., due to drift of the EUV source) varies over time.

[0012] Provided the illumination optics are designed such that the design of the second facet, and particularly the number and arrangement of the second individual mirrors forming the second facet, can vary according to the illumination configuration, the intensity sensor, adapted to this dimensional variability, can also have variable dimensions or variable boundary shapes. Such variable dimensions or boundary shapes of the intensity sensor can be achieved by specifying intensity sensors of different sizes. Alternatively or additionally, the variability in the size or boundary shape of the intensity sensor can be achieved by apertures separately assigned to the intensity sensor in the illumination beam path upstream of the intensity sensor and / or by the pixel design of the intensity sensor, wherein, depending on the size and shape of the second facet, such a pixelated intensity sensor reads only from sensor pixels whose arrangement corresponds to the size or shape of the second facet in each case.

[0013] The number of intensity sensors according to claim 2 allows for sufficient spatial resolution to measure the object field coordinates according to the required profile. When measuring the object field coordinates, the number of intensity sensors can be in the range of 4 to 100, specifically between 5 and 50 (e.g., about 10 or about 25). In the case of measuring two field dimensions, such as the far field in which the first faceted mirror is arranged, which is intended to be measured by means of an intensity sensor arrangement, the number of intensity sensors can also be greater than 100 and can be in the range of 100 to 1000.

[0014] The arrangement of the intensity sensors as described in claim 3 utilizes the fact that the illumination light in the region of the second individual mirror exists regularly in a faceted channel focusing form, because in typical applications, the light source is at least approximately imaged onto the arrangement plane of the second faceted mirror. The adjacent arrangement of the intensity sensors to the second individual mirror of the second faceted mirror then allows the intensity sensors to be arranged compactly next to each other.

[0015] The sensor row as described in claim 4 is particularly compact.

[0016] The arrangement of individual sensor mirrors as described in claim 5 allows for 2D far-field measurements, wherein the measurement position of the individual sensor mirror serves as a measurement support point from which extrapolation can then be performed to determine the entire 2D far field.

[0017] The advantages of the method as described in claim 6 correspond to those advantages explained above in conjunction with the illumination optics unit.

[0018] This results in a particularly precise measurement of the dependence of the illumination light intensity on the coordinates of the detected object field, which can be performed in parallel with the operation of the illumination optics unit. To prepare for the evaluation step of the measurement method, the intensity sensor can be calibrated, for example, using an illumination device with a constant illumination intensity in the detected object field coordinates. Following the evaluation step can be a correction step, in which the individual mirror assignments or facet assignments are changed so that the actual value of the illumination intensity distribution in the detected object field coordinates approximates the target value. The resulting correction can be performed in such a way that the illumination angular distribution of the illumination from the illumination optics unit to the object field remains unchanged due to the correction.

[0019] The advantages of the method as described in claim 7 correspond to the advantages of the illumination optical unit as described in claim 5.

[0020] The advantages of the lighting system as claimed in claim 8, the optical system as claimed in claim 9, the projection exposure apparatus as claimed in claim 10, the manufacturing method as claimed in claim 11, and the microstructure or nanostructure component as claimed in claim 12 correspond to those advantages already explained above with reference to the lighting optical unit according to the invention or the measurement method according to the invention. This allows for the possibility of particularly accurate and high-resolution component manufacturing due to the precisely measured and, if appropriate, corrected illumination intensity distribution on the detection object field coordinates. In the manufacturing method as claimed in claim 11, the aforementioned measurement method can be particularly used to specify optimized illumination settings.

[0021] In particular, it can produce semiconductor components in the form of microchips, especially memory chips. Attached Figure Description

[0022] Exemplary embodiments of the present invention will now be explained in more detail with reference to the accompanying drawings, in which:

[0023] Figure 1 The projection exposure apparatus for EUV microlithography is shown very schematically in a meridional section, which includes a light source, an illumination optics unit, and a projection optics unit, wherein a plan view of the object field of the projection exposure apparatus is shown in the illustration;

[0024] Figure 2 Schematably and similarly shown in meridional sections according to Figure 1 The beam path of a selected individual illumination ray within the illumination optical unit, which originates from the central focal point and extends to the mask or object in the object plane of the projection optical unit arranged in the area of ​​illumination or object field;

[0025] Figure 3 A plan view showing details of the first faceted mirror of the illumination optics unit of the projection exposure apparatus, wherein the individual mirror group forming the first faceted mirror is highlighted, through which a portion of the illumination light beam is imaged into the object field via the individual mirror forming the second faceted mirror of the illumination optics unit;

[0026] Figure 4 With similar Figure 3 The diagram shows details of another embodiment of the first faceted reflector, again featuring a separate set of reflectors highlighted, which, as the first facet, is imaged into the object field via a second facet distributed by the second facet reflector.

[0027] Figure 5 With similar Figure 3 and Figure 4 The diagram shows the diagram with the following features: Figure 4A plan view of the arrangement of individual reflectors of the first faceted reflectors, showing the allocation of the first faceted reflectors, each first facet being formed by a group of individual reflectors that image onto the object field while being superimposed on each other, wherein the sensor individual reflectors of the intensity sensor device for measuring the dependence of the intensity of illumination light incident on the object field on the coordinates of the detected object field are additionally highlighted between these groups of individual reflectors.

[0028] Figure 6 An embodiment of an illumination optical unit of a projection exposure apparatus including a first faceted mirror and a second faceted mirror is schematically and perspectively shown, wherein an illumination beam path is shown between the light source and the intensity sensor of the intensity sensor row of the intensity sensor device, which is guided via one of the individual reflectors of the sensor of the first faceted mirror.

[0029] Figure 7 This illustrates the dependence of the field height coordinate x in the corresponding column of the individual mirror group of the variant of the first faceted reflector on the field height x (horizontal coordinate) of the object field of the first faceted reflector when the illumination setting is "y-dipole". G The graph (vertical axis) shows the distribution of individual mirrors to field height x, resulting in a total of eight individual mirror columns (j=1,…8).

[0030] Figure 8 Again, a planar diagram illustrates an example of the distribution of the individual sensor mirrors on a variant of the first faceted mirror, with... Figure 5 In contrast, the variant of the first faceted mirror has a very large number of individual mirrors;

[0031] Figure 9 The figure shows the target illumination intensity I in the object field. SOLL (Dashed line) and the actual lighting intensity I before correction IST (Solid line) Field dependence;

[0032] Figure 10 With similar Figure 9 The diagram shows the results based on Figure 6 The intensity measurement value of the intensity sensor on the sensor row, where the calibration measurement value I K (Dashed line) is used to indicate the following: Figure 9 The target lighting intensity, and the actual measured value I M (Solid line) is used to indicate that... Figure 9 The situation regarding the uncorrected distribution of lighting intensity; and

[0033] Figure 11 The comparison of relative changes with high field dependence is shown, firstly in the case of... Figure 9 As a relative intensity deviation I ISTIn the case of (dashed line) lighting, the second is as follows: Figure 10 The relative measurement deviation I between the two measurement curves (solid line) IST M This is to illustrate the measurement quality of the intensity sensor device that can be used for subsequent calibration. Detailed Implementation

[0034] exist Figure 1 The microlithography projection exposure apparatus 1, shown schematically in a meridional section, has a light source 2 for illumination light 3. The light source 2 is an EUV light source that produces light in the wavelength range between 5 nm and 30 nm. This can be an LPP (laser-generated plasma) light source, a DPP (discharge-generated plasma) light source, or a synchrotron radiation-based light source, such as a free-electron laser (FEL).

[0035] The transmission optical unit 4 is used to guide the illumination light 3 emitted from the light source 2. This transmission optical unit has a light collector 5 and a transmission faceted reflector 6, the light collector 5 being... Figure 1 Only its reflection effect is shown below. The transmission surfaced mirror 6 is described in more detail below and is also referred to as the first surfaced mirror or the field surfaced mirror. The intermediate focal point 5a of the illumination light 3 is arranged between the light collector 5 and the transmission surfaced mirror 6. The numerical aperture of the illumination light 3 in the region of the intermediate focal point 5a is, for example, NA = 0.182. The illumination specification surfaced mirror 7 (which is also referred to as the second or another surfaced mirror and is also described in more detail below) is located downstream of the transmission surfaced mirror 6, and therefore downstream of the transmission optical unit 4. Optical components 5 to 7 are part of the illumination optical unit 11 of the projection exposure apparatus 1.

[0036] The transmission faceted reflector 6 is arranged in the field plane of the illumination optical unit 11 in the far field of the illumination light of the light source 2.

[0037] The illumination specification faceted reflector 7 of the illumination optical unit 11 is arranged at a certain distance from the pupil plane of the illumination optical unit 11. Such an arrangement is also called a specular reflector.

[0038] In an alternative embodiment of the illumination optical unit, the second faceted mirror 7 may also be arranged in the pupil plane of the illumination optical unit 11, and in this case, it is a pupil faceted mirror.

[0039] The object to be illuminated is positioned downstream of the illumination pattern faceted reflector 7 in the beam path of the illumination light 3, in the form of a mask master 12. This mask master is arranged in the object plane 9 of the downstream projection optics unit 10 of the projection exposure apparatus 1. The projection optics unit 10 is a projection lens. The illumination optics unit 11 is used to illuminate the object field 8 on the mask master 12 in the object plane 9 in a defined manner. The object field 8 simultaneously constitutes the illumination field of the illumination optics unit 11. Typically, the illumination field is configured such that the object field 8 can be arranged within the illumination field.

[0040] Similar to the transmission faceted mirror 6, the illumination specification faceted mirror 7 is also part of the pupil illumination unit of the illumination optics unit, used to illuminate the incident pupil 12a in the pupil plane 12b of the projection optics unit 10 with illumination light 3 having a specified pupil intensity distribution. The incident pupil 12a of the projection optics unit 10 can be arranged in the illumination beam path upstream or downstream of the object field 8. Figure 1 This illustrates the case where the incident pupil 12a is positioned in the illumination beam path downstream of the object field 8. In this case, the pupil distance PA between the second faceted mirror 7 and the pupil plane 12b is the sum of the z-distance PA1 between the second faceted mirror 7 and the object plane 9 and the z-distance PA2 between the object plane 9 and the pupil plane 12b. The following holds true in the z-direction: PA = PA1 + PA2. The pupil distance PA can also be measured in the beam direction.

[0041] To facilitate the representation of positional relationships, the Cartesian xyz coordinate system will be used in the following text. Figure 1 In the figure, the x-direction extends perpendicularly to the attached plane and into the attached plane. The y-direction is... Figure 1 Extending to the right from the center. The z-direction is... Figure 1 The coordinate system used in the figures extends downwards. The x-axis extends parallel to each other in each case. The z-axis of the coordinate system follows the corresponding principal direction of the illumination light 3 within the corresponding figure under consideration.

[0042] Object field 8 has an arc or partially circular shape, defined by two parallel circular arcs and two straight side boundaries. These two straight side boundaries extend in the y-direction for a length of y0 and are separated by a distance x0 from each other in the x-direction. The aspect ratio x0 / y0 is 13:1. Figure 1 The illustration shows a plan view of the object field 8, which is not drawn to scale. The boundary shape 8a is arcuate. In an alternative and equally possible object field 8, its boundary shape is rectangular, also with an aspect ratio of x0 / y0.

[0043] The mask master 12 is displaced along the object displacement direction y through the object field 8 during projection exposure.

[0044] Projection optical unit 10 in Figure 1The diagram shows only partially and highly schematically. The object-side numerical aperture 13 and image-side numerical aperture 14 of the projection optical unit 10 are shown. Other optical components of the projection optical unit 10 for guiding the illumination light 3 between the shown optical components 15 and 16 are also shown. Figure 1 (Not shown) is located between these optical components 15, 16, which can be implemented as, for example, a reflector that reflects EUV illumination light 3.

[0045] The projection optics unit 10 images the object field 8 onto the image field 17 in the image plane 18 on the wafer 19, which, like the mask master 12, is supported by a holder (not shown in more detail). Both the mask master holder and the wafer holder can be moved in the x and y directions by corresponding displacement actuators. The mounting space required for the wafer holder is within... Figure 1 The mounting space requirement 20 is shown as a rectangular frame. The extent of the mounting space requirement 20 in the x, y, and z directions depends on the components to be housed within it. The mounting space requirement 20 extends, for example, 1 m in the x and y directions from the center of the image field 17. In the z direction, the mounting space requirement 20 also extends, for example, 1 m from the image plane 18. The illumination light 3 must be guided in the illumination optics unit 11 and the projection optics unit 10 such that it is guided through the mounting space requirement 20 in each case.

[0046] The transmission surfaced mirror 6 has multiple transmission surfaces, also referred to as the first surface. The transmission surfaced mirror 6 can be implemented as a MEMS mirror. The transmission surface is a separate mirror 21, which can switch between at least two tilt positions and is implemented as a micromirror. The separate mirror 21 can be implemented as a micromirror that can be tilted in a driven manner about two mutually perpendicular rotation axes.

[0047] In these individual mirrors 21, according to Figure 2 The yz cross-sectional view schematically shows a row of a total of nine individual reflectors 21, which are in... Figure 2 The indices are 211 to 219 from left to right. In fact, the transmission faceted mirror 6 has significantly more transmission facets 21. The transmission facets 21 are divided into multiple transmission facet groups, which are not... Figure 2 The diagram is shown in more specific detail. These transmission facet groups are also called individual mirror groups, virtual field facets, or virtual facet groups.

[0048] Each transmission facet group guides a component of the illumination light 3 (also referred to as a partial illumination beam) via an illumination channel to partially or completely illuminate the object field 8. This illumination channel and the partial illumination beam 3 guided by it... i (See) Figure 2As shown in the partial beams I to IX), exactly one illumination specification plane 25 of the illumination specification plane mirror 7 is assigned to one of the individual mirror groups or the transmission plane group in each case. In principle, each of the illumination specification planes 25 can itself be constructed from multiple individual mirrors. The illumination specification plane 25 is also referred to below as the second plane.

[0049] For further details regarding possible embodiments of the transmission faceted reflector 6 and the projection optical unit 10, refer to WO2010 / 099 807 A.

[0050] At least some of the illumination specification facets 25 illuminate only a portion of the object field 8 or a portion of the field. This portion of the field is shaped very independently and is further dependent on the desired distribution of illumination directions (pupil shape) in the object field 8, i.e., the illumination setting. The illumination specification facets 25 are therefore illuminated by virtual field facets of very different shapes, whose shapes precisely correspond to the shapes of the corresponding portions of the field to be illuminated. Furthermore, each illumination specification facet 25 contributes to a different region of the pupil depending on its position in the object field 8.

[0051] The illumination specification facet 7 can be implemented as a MEMS mirror, particularly if each of the illumination specification facets 25 is constructed from multiple individual mirrors. The illumination specification facet 25 is a micromirror that can switch between at least two tilt positions. The illumination specification facet 25 is implemented as a micromirror that can be continuously and independently tilted in a driven manner about two mutually perpendicular tilt axes, i.e., the micromirror can be positioned to multiple different tilt positions.

[0052] An example of a designated allocation of individual transmission facet 21 to lighting specification facet 25 is illustrated in Figure 2 In each case, the illumination specification facets 25 assigned to transmission facets 211 to 219 are indexed according to this assignment. Illumination facets 25 are illuminated from left to right in the order of 256, 258, 253, 254, 251, 257, 255, 252 and 259 based on this assignment.

[0053] Facets 21 and 25, indices 6, 8, and 3, contain three illumination channels VI, VIII, and III, which illuminate three object field points OF1, OF2, and OF3 from a first illumination direction. These object field points are located at... Figure 2 Numbered from left to right. Indices 4, 1, and 7 of facets 21 and 25 belong to the three additional illumination channels IV, I, and VII that illuminate the three object points OF1 to OF3 from the second illumination direction. Indices 5, 2, and 9 of facets 21 and 25 relate to the three additional illumination channels V, II, and IX that illuminate the three object points OF1 to OF3 from the third illumination direction.

[0054] Assign lighting to the following directions:

[0055] -Lighting channels VI, VIII, III,

[0056] - Illumination channels IV, I, VII, and

[0057] - Illumination channels V, II, IX

[0058] The same applies in every case. Therefore, the allocation of the transmission plane 21 to the illumination specification plane 25 results in telecentric illumination of the object field 8 in the case of the illustrated illumination example.

[0059] The object field 8 can be illuminated via a transmission faceted reflector 6 in the form of a specular reflector and an illumination specification faceted reflector 7. The principle of the specular reflector is known from US 2006 / 0132747 A1.

[0060] Figure 3 A schematic plan view shows details of a first faceted reflector 6, including a square first facet 21 arranged in an array tilted at 45° relative to the xy coordinate system. Therefore, the rows and columns of this array extend at 45° angles relative to the x and y directions, respectively.

[0061] exist Figure 3 In the middle, the individual reflector 21 is highlighted. G1 Up to 21 G11 The individual mirror group 26, which serves as the first facet, is imaged into the object field 8 via the correspondingly assigned second facet 25 of the second facet mirror 15.

[0062] Individual mirror 21 of individual mirror group 26 Gi Located within the arc-shaped boundary 27 of the individual mirror group 26. In fact, the individual mirror 21 belongs to the corresponding individual mirror group 26. Gi In practice, the number is much larger, for example, it can be between 15 and 50 or even more.

[0063] Some of the individual mirrors 21 of the first faceted mirror 6 are located only partially within the group boundary 27. Here, the tilt of the respective individual mirrors 21, controlled accordingly by the illumination optics unit 11, can be used to determine whether these individual mirrors 21 partially located within the group boundary 27 should belong to the individual mirror group 26. For example, with at least 60% of its reflective surface or such Figure 3 Individual mirrors 21, whose reflective surface is at least 100% located within group boundary 27, can be assigned to individual mirror group 26. In areas where the reflective surface of each individual mirror 21 within group boundary 27 is 50%, there are some individual mirrors 21 that, given this selection criterion, cannot be assigned to... Figure 3The individual mirror group 26 highlighted in the diagram cannot be assigned to adjacent individual mirror groups because, in the case of the group assignment shown, the reflecting surface of such individual mirrors 21 located at the limit of the group boundary 27 reaches the minimum surface area limit within the corresponding group boundary 27 where there is no individual mirror group. Some of these individual mirrors 21 are in Figure 3 The individual reflector 21 is highlighted as a potential sensor. S Regarding imaging in the object field 8 from adjacent individual mirrors 21, this potential sensor individual mirror 21 S Different field heights x assigned to individual mirror groups 26 i That is, the different x-coordinates of the individual mirror group 26 imaged onto the object field 8. Such a field height x i (i=1 to 11) in Figure 3 Highlighted in the image. These potential sensors are individually reflected by mirror 21. S Therefore, the field height x represents the corresponding allocation at the detection field coordinate x. i The illumination intensity of the far field of illumination light at the location of the illumination light extends along the individual reflector and varies only slightly along the spatial coordinates x and y of the field-splitting reflector 6, and the field-splitting reflector 6 is arranged in the far field of illumination light.

[0064] These potential sensors have individual reflectors 21 S Each of the individual mirrors 21 directly adjacent to the individual mirror group 26 Gi .

[0065] Figure 4 With similar Figure 3 The diagram illustrates a variation of the first faceted reflector 6. (Referring to the one already mentioned above...) Figures 1 to 3 And especially referencing Figure 3 The components and functions explained have the same reference numerals and will not be discussed in detail.

[0066] according to Figure 4 The field-division mirror 6 has an array arrangement of individual mirrors 21 tilted relative to the xy coordinate system. Therefore, the rows and columns of this array arrangement extend in the x and y directions.

[0067] 21 individual mirrors Gi (i=1 to 18) in Figure 4 It is highlighted again in the middle. According to Figure 4 The arrangement also highlights some potential individual sensor reflectors 21 S and its field height x i (i=1 to 9).

[0068] Figure 5One embodiment of the display field-faceted reflector 6 is shown, along with a typical arrangement of individual reflector groups 26 having corresponding group boundaries 27. According to... Figure 5 In the case of allocation, these individual mirror groups 26 are configured according to Figure 4 The individual mirror groups are arranged in two columns in each of the four individual mirror groups 26. Figure 5 This illustrates that between every two adjacent individual mirror groups 26 in one column, there is a sensor individual mirror 21 at each of the field heights x1 to x9. S It does not belong to any individual mirror group 26. For according to Figure 3 The arrangement of individual reflectors 21 tilted relative to the xy coordinate axes produces a similar effect. Figure 5 The corresponding allocation.

[0069] Figure 6 The main components of the illumination optics unit 11 are first shown in a perspective schematic diagram, followed by the main components of the intensity sensor device 31, which measures the dependence of the intensity of the illumination light 3 incident on the object field 8 on the detection object field coordinate x. The intensity sensor device 31 includes a separate reflector 21 of the potential sensor. S Selected sensor individual reflector 21 Si Potential sensor individual reflector 21 S This is generated by the individual mirror 21 of the field-division mirror 6, which cannot be used in the individual mirror group 26, as described above. Figures 3 to 5 As already explained. Furthermore, the intensity sensor device 31 includes a plurality of intensity sensors 321 to 329, which are arranged in a sensor row 33 and spatially adjacent to the individual reflectors 34 of the second faceted reflector 7. Compared to the individual reflectors 34 of the second faceted reflector 7, the intensity sensors 321 to 329... i exist Figure 6 The dimensions are exaggerated. Intensity sensor 32. i It corresponds to the second facet 25 in terms of shape and surface area. This ensures that the light loss due to overexposure of the second facet 25 is in magnitude the same as that due to the intensity sensor 32. i The light loss due to overexposure is similar, so the sensor signal remains proportional to the intensity in the object field 8, even if the light loss (e.g., due to light loss from drift source plasma) changes over time.

[0070] If the second facet 25 is not a physical facet of fixed size, but a virtual facet in the form of a group of second individual reflectors 34, then the second facet 25 will have different shapes and sizes depending on the application. In this case, the intensity sensor 32 iIt can also have variable dimensions. This can be achieved by using a greater number of sensors of different sizes, an additional aperture upstream of the sensor, or a pixelated sensor that only reads partially.

[0071] Figure 6 The beam path of the illumination light 3 is shown, which originates from the light source 2 or the intermediate focal point 5a via the sensor's individual reflector 21. S One of them (specifically type 21) S1 The sensor reflector guides the sensor to the assigned intensity sensor 321.

[0072] The illumination beam 31 is also schematically shown being guided from the light source 2 or the intermediate focal point 5a to the object field 8 via a separate set of mirrors 261 and a second facet 251.

[0073] exist Figure 6 In the middle, the corresponding shading is used to highlight according to Figure 4 and Figure 5 Two separate mirror groups 261 and 262, in the form of separate mirror groups 26, image onto the object field 8 while being superimposed on each other via associated second facets 251 and 252. In the illustrated design, the second facet 25... i Each of the second facets 251 is composed of a 2 × 2 array of individual mirrors 34 of the second facet 7. In fact, the second facet 251 can also be composed of exactly one individual mirror 34, or it can be constructed from a different number of individual mirrors 34, such as 3 × 3, 4 × 4, 5 × 5 arrays, 6 × 6 arrays or 7 × 7 arrays.

[0074] As in accordance with Figure 4 and Figure 5 In the case of a single mirror group 26, also according to Figure 6 In the case of the illumination optics unit 11, the individual mirror groups 26, which simultaneously image onto the object field 8 while being superimposed on each other, are exactly nine individual mirrors 21 wide in the x-direction. These nine individual mirrors 21 are assigned to field heights x1 to x9. Therefore, each individual mirror group 26 includes individual mirrors 21 from nine adjacent columns 1 to 9. Based on this nine-column subdivision of the individual mirror groups 26 and the subsequent field height allocation, this results in the selection of sensor individual mirrors 21 for the impact intensity sensors 321 to 329. S1 Up to 21 S9 Type classification.

[0075] Type 21 S1 The individual reflector of the sensor is a single reflector 21 arranged in the same column as the individual reflector 21 arranged in the first left column of the corresponding individual reflector group 26. Type 21 S1 The sensor's individual reflector therefore belongs to the field height x1.

[0076] Correspondingly, other types of sensors use separate reflectors 21 S2 ,twenty one S3 Individual mirrors 21 belonging to the field-division mirror 6 are arranged in the same columns as the individual mirrors 21 in the second, third, ... columns of the corresponding individual mirror groups 26. These are additional sensor individual mirrors 21 of this type. S2 ,twenty one S3 ,…twenty one S3 Therefore, it belongs to the field heights x2, x3, ...

[0077] Individual mirror group 26 and sensor individual mirror 21 Si This nine-column subdivision enables the measurement spatial resolution of the intensity dependence of the illumination light 3 incident on the object field 8 to be divided into the left edge x of the object field 8. l and right edge x r The nine field height sections x1 to x9 are between. Figure 6 The diagram for object field 8 illustrates the nine field height portions x1 to x9. When the individual mirror groups 26 simultaneously image onto object field 8 while superimposing on each other, the imaging causes image inversion, resulting in... Figure 6 The object field 8 in the image exhibits curvature in the opposite direction compared to the individual mirror group 26.

[0078] Intensity sensor 32 i Type 21, which is assigned to a separate reflector for the sensor. Si The order of these sensors is arranged within sensor row 33. Intensity sensor 32 i The order of this line is not mandatory; it is only necessary to know the intensity sensor 32. i Individual reflector 21 for the sensor Si The type of allocation is the allocation of the field height portions x1 to x9 that are respectively measurable by the latter.

[0079] Therefore, it can be done through type 2 1S1 The individual reflector and the assigned intensity sensor 321 determine the intensity measurement of the field height portion x1 of the detection object at field coordinate x, which is arranged on the left. With necessary modifications, this also applies to type 21. S2 Up to 21 S9 The sensor has a separate reflector and intensity sensors 322 to 329 assigned to the field height portions x2 to x9. Intensity sensors 322 are located within the entire sensor row 33. i Obtain the corresponding type 21 Si The illumination light 3 can be used to measure the intensity of the illumination light incident thereon on the entire object field 8, and thus the object field coordinates x can be detected.

[0080] Figure 7Displaying 26 individual mirror groups i The allocation association with the individual reflector columns on the field-split reflector 6. Figure 7 It shows the relationship with the data. Figure 5 and Figure 6 The schematic arrangement shows different scenarios, namely, a total of 8 columns of individual mirror groups 26 are arranged on the faceted mirror 6. i j (j=1 to 8). A single mirror group 26 is shown. i j The number N G Dependence on the spatial coordinate x of the field-plane reflector 6. Based on the eight-column arrangement, individual reflector group 26. i j It exists at position x in eight columns j=1 to j=8.

[0081] The case where the field-plane reflector 6 comprises a very large number of individual reflectors 21 differs from the case based on Figures 3 to 6 A schematic diagram, Figure 8 A single reflector 21 for the potential sensor is shown. S The distribution across the entire surface of the first faceted reflector 6. This figure illustrates the individual reflector 21 for a potential sensor at a specific x-field location. S The selection, i.e., for a total of five exemplary x-field locations (left field edge (x=x) l ), center of the field (x=0), right edge of the field (x=x) r ) and between the left edge and the center (x=x l / 2) and between the center and the right edge of the field (x=x r The other two x positions of / 2).

[0082] Regarding a large number of individual mirror groups 26 i j Given according to Figure 8 Potential sensor individual reflector 21 S The distribution of the sensors produces individual reflectors 21 that can be used in the intensity device 31. Si A good statistical distribution. For these sensors, individual reflectors 21 S Each of them, due to the adjacent individual mirrors 21 to the corresponding individual mirror group 26 of the field-division mirror 6. i j The allocation of this information results in individual reflectors 21 for each sensor. S In the separate reflector 21 adjacent to the sensor Si 26 individual mirror groups i j The x-coordinate is represented by the illumination field 8. Correspondingly, the corresponding sensor uses a separate reflector 21.S Individual mirror type 21 can be assigned to the sensor Si One of them, for example, the combination above Figure 6 Type 21 of the description S1 Up to 21 S9 .

[0083] Based on the potential sensor individual reflector 21 S The achievable spatial resolution, intensity sensor 32 of intensity sensor device 31 i The quantity can also be smaller or larger. The number i can be in the range of 3 to 100.

[0084] Figures 9 to 11 This indicates the measurement accuracy of the intensity sensor device 31 when the intensity of the illumination light depends significantly on the x-coordinate of the detected object field.

[0085] Figure 9 The desired target intensity distribution I is illustrated by dashed lines in the example. SOLL It is constant across the entire x-coordinate of the object field. Figure 9 An exemplary actual intensity distribution I is shown as a solid line. IST For example, it has a cosine distribution on the x-coordinate of the object field 8, and also, as an example, the intensity I is greater than that of the object field 8 within the range of maximum values. SOLL It is about 10% larger (stronger), and within the range of minimum cosine strength, it is stronger than I. SOLL Smaller (less powerful) by about 10%.

[0086] Figure 10 The dashed line shows the relationship based on Figure 9 Constant illumination intensity distribution I SOLL Intensity sensor 32 assigned to the corresponding x-coordinate (i.e., assigned to the corresponding field height) of object field 8 i Corrected measurement results I (i=1 to 9) K Because each sensor is assigned a separate reflector 21. Si 32 intensity sensors i The measured x-position is at Figure 10 The x-axis is represented by numbers "1" to "9". This corresponds to the constant illumination intensity I on the x-axis of the object field. SOLL Different, intensity sensor 32 i Corrected intensity profile I measured by the dashed line on the x-coordinate K It is not constant. This is consistent with practice, where cumulative intensity irradiation or different types of 21 S1 Up to 21 S9 The quantity does not need to be constant. Figure 10 In the actual cases shown, for example, there are relatively few types 21. S1 ,twenty oneS7 and 21 S9 The sensor has a separate reflector, which makes the intensity value measured there relatively small compared to other measurements. Figure 10 The correction measurement values ​​I of these dashed lines in the figure K A calibration curve is used for the intensity sensor device 31. This calibration curve can be determined, for example, by measuring a projection exposure device, where the object field 8 is in some other way ensured to conform to the distribution I. SOLL Illumination is provided with a uniform distribution of light intensity.

[0087] Used according to Figure 9 Lighting intensity distribution I IST The measured values ​​I of the intensity sensors 321 to 329 M exist Figure 10 The line is drawn as a solid line. Even without calculating relative changes, Figure 10 The comparison between the dashed and solid curves in the diagram also shows that the actual intensity distribution I... IST In the region of the middle x-coordinate, compared to the target distribution I SOLL The lighting intensity is low, but higher in the regions at the edges of the left and right x-coordinates.

[0088] Figure 11 It shows Figure 10 The measured value I is depicted by solid and dashed lines. M and I K The ratio is formed as a solid line ratio measurement result I IST M ,Right now Figure 10 The value I is shown as a solid line and normalized to the dashed line. K The measured value I M In comparison, Figure 11 The actual illumination intensity distribution I on the x-coordinate of the detection field is shown again by dashed lines. IST That is, in principle with Figure 9 The curve shown as a solid line is the same. (And...) Figure 9 Conversely, the illumination intensity distribution I IST exist Figure 11 The distribution is plotted as I relative to the target intensity. SOLL The ratio of .

[0089] therefore, Figure 11 The vertical axis in the figure represents the ratio I. M / I K Or I IST / I SOLL .

[0090] Figure 11 The measured actual value I of the illumination intensity distribution on the x-coordinate of the detection field 8 is shown. IST Mand actual value I IST A good correspondence between them.

[0091] These two curves I IST and I IST M The deviation between them can be at most on the order of 3%, 2.5%, 2%, or even smaller.

[0092] In addition, such as Figure 8 As shown, the sensor has a separate reflector 21. S It can be selected so that they cover the usage area of ​​the illumination light far field in both far field dimensions x and y on the entire field-divided reflector 6.

[0093] Because a single mirror 21 of the sensor can be used S The arrangement covers the usage area of ​​the illumination light far field in both far field dimensions x and y, thus allowing for complete measurement of the light source far field in both x and y dimensions in the arrangement plane of the field-division mirror 6 by a corresponding embodiment of the intensity sensor device 31. Furthermore, this embodiment of the intensity sensor device 31 has a larger number of intensity sensors 32. j i It covers the two-dimensionality of far-field measurements. This intensity sensor device can have, for example, intensity sensors 32 arranged in an array comprising j rows and i columns. i j As explained above in conjunction with sensor row 33, since only the individual reflector 21 of the corresponding sensor needs to be known... S To the corresponding strength sensor 32 i j The location allocation, therefore intensity sensor 32 i j The array arrangement does not require a separate reflector corresponding to the sensor used for measurement.21 S The arrangement.

[0094] Measuring the dependence of the intensity of the illumination light 3 incident on the object field 8 on the detection object field coordinate x involves first positioning the individual mirror 21 of the first faceted mirror 6 of the illumination optical unit 11 relative to the individual mirror group 26 of the first faceted mirror 6. i The second facet 25 assigned to the second facet mirror 7 i The second facet will group these 26 individual mirrors. i At least part of the field of object field 8 is imaged.

[0095] Subsequently, individual mirrors 21 that were not used in this allocation of the first faceted mirror 6 were selected. These selected, unused individual mirrors 21 were chosen as sensor individual mirrors 21 for the intensity sensor device 31. S .

[0096] Subsequently, the selected sensor was individually reflected by mirror 21. S Coordinates are assigned to the corresponding detection field coordinates x. i Among them, the individual reflector 21 of the sensor to be assigned S The individual mirrors 21 of the directly adjacent first faceted mirror 6 are imaged into the object field 8. As described above, this corresponds to the individual mirror 21 of the respective sensor. S Individual reflector type 21 to sensor Si The allocation.

[0097] Then, based on the performed coordinate assignment, the intensity sensor 32 i The corresponding one is assigned to the corresponding detection object field coordinate x. i 32 individual reflectors for the sensor Si .

[0098] Partial illumination light 3 then serves as detection illumination light via the field coordinates assigned to the corresponding detection object or the field height portion x. i Individual reflector 21 of the sensor Si Guided to the assigned intensity sensor 32 i This can be performed in parallel with the projected exposure. Then, the intensity of the illumination light hitting sensor 32 is evaluated. i Sensor data is used to determine the intensity I of the illumination light 3 incident on the object field 8. IST Dependence on at least one detected object field coordinate x.

[0099] After evaluating the sensor data, the intensity dependence of illumination intensity on the x-coordinate of the detected object field can be corrected, for example, by modifying the individual mirrors 21 of the first faceted reflector 6 to the individual mirror groups 26. i The allocation, or by modifying the individual mirror group 26 i To the second section 25 i The allocation.

[0100] Projection exposure can be performed in parallel with measurements or after appropriate calibration.

[0101] Selecting and assigning individual reflectors to sensors 21 S Furthermore, the evaluation of sensor data can be achieved by generating 2D far-field measurements from the evaluated sensor data. The selected and assigned sensor uses individual reflectors 21. S The corresponding data can form support points for measuring the far field, and the entire far field can then be inferred between these support points using extrapolation.

[0102] To fabricate microstructured components, particularly highly integrated semiconductor components (e.g., memory chips), using projection exposure apparatus 1, a mask 12 and a wafer 19 are first provided. Subsequently, the structure on the mask 12 is illuminated by illumination light 3 using illumination optics 11 and projected onto a photosensitive layer on the wafer 19 using projection optics of projection exposure apparatus 1. By developing the photosensitive layer, microstructures are then formed on the wafer 19, thereby producing microstructured or nanostructured components.

[0103] The components produced can be microchips, especially memory chips.

Claims

1. An illumination optical unit (11) - Includes a first faceted reflector (6), which includes a first individual reflector (21) for reflectively guiding the illumination light (3) from the EUV light source (2) and is arranged in the usage area of ​​the illumination light in the far field. - Includes a second faceted reflector (7) for reflectively guiding the illumination light (3) reflected from the first faceted reflector (6) to an object field (8), in which an object (12) to be illuminated can be arranged, wherein the second faceted reflector (7) has a second separate reflector (34) forming a second facet (25), the second separate reflector (34) receiving a portion of the illumination light (3) via a portion of the beam (3) of the illumination light (3). i The individual mirror group (26) forming the first facet of the first facet mirror (6) will image at least a portion of the field of the object field (8). - Includes an intensity sensor device (31) for measuring the intensity (I) of the illumination light (3) incident on the object field (8). IST The dependence of at least one detected object field coordinate (x) on the object field coordinate, where, The intensity sensor device (31) has: -- Multiple first individual reflectors constitute the sensor individual reflector (21) of the first faceted reflector (6). S ), wherein the sensor has a separate reflector (21) S The detected object field coordinates (x) are assigned to multiple different object field locations (x, x). i ), -- Multiple intensity sensors (32) i ), wherein the sensor has a separate reflector (21) S The design is intended to reflectively guide the illumination light (3) to the intensity sensor (32). i ).

2. The illumination optical unit according to claim 1, characterized in that, Intensity sensor (32) i The number of () is in the range of 3 to 100.

3. The illumination optical unit according to claim 1 or 2, characterized in that, The intensity sensor (32) i The second individual mirror (34) is arranged spatially adjacent to the second faceted mirror (7).

4. The illumination optical unit according to any one of claims 1 to 3, characterized in that, The intensity sensor (32) i Arranged as sensor rows (33).

5. The illumination optical unit according to any one of claims 1 to 4, characterized in that, The sensor's individual reflector (21) S The sensor is arranged on the first faceted reflector (6) such that the individual reflector of the sensor covers the usage area of ​​the far field of the illumination light in two far field dimensions (x, y).

6. A method for measuring the intensity (I) of illumination light (3) incident on an object field (8) using an illumination optical unit (11) as described in any one of claims 1 to 5. IST A method for detecting the dependence of at least one object field coordinate (x) includes the following steps: - Regarding the individual mirror group (26) of the first faceted reflector (6) forming the first facet, i ), and assign the individual mirror (21) of the first faceted mirror (6) of the illumination optical unit (11) to the second facet (25) of the second faceted mirror (7). i The second facet will hold these individual mirror groups (26) i At least a portion of the field of the object field (8) is imaged. - Select the individual reflector (21) of the first faceted reflector (6) that was not used for this allocation as the sensor individual reflector (21) of the intensity sensor device (31). S ), - Select the sensor individually as a reflector (21) S ) coordinates assigned to the detection field coordinates (x i ), where a single reflector (21) is directly adjacent to the sensor. S The individual mirror (21) of the first faceted mirror (6) of the object field (8) is imaged into the object field (8). - Assign the intensity sensor (32) according to the coordinates. i The corresponding sensor in ) is assigned to the sensor's individual reflector (21) assigned to the corresponding detection field coordinate (x). S ), and via the coordinates assigned to the corresponding detection field (x i ) sensor individual reflector (21 S The detection illumination light (3) is directed to the assigned intensity sensor (32). i ), - Evaluate the intensity sensor (32) irradiated by the detection illumination light (3). i Sensor data is used to determine the intensity (I) of the illumination light (3) incident on the object field (8). IST The dependence of the at least one detected object field coordinate (x).

7. The method according to claim 6, characterized in that, Select and assign the individual reflectors of the sensor (21) S The sensor data is evaluated such that a 2D far-field measurement of the illumination light far field is generated from the evaluated sensor data.

8. A lighting system comprising a lighting optical unit (11) as claimed in any one of claims 1 to 5, and comprising an EUV light source (2).

9. An optical system comprising an illumination optical unit (11) as claimed in any one of claims 1 to 5, and a projection optical unit (10) for imaging the object field (8) onto an image field (17).

10. A projection exposure apparatus comprising the optical system as described in claim 9 and comprising an EUV light source (2).

11. A method for producing microstructured or nanostructured components, comprising the following steps: - Provide a mask master (12). - Provide a wafer (19) with a coating that is sensitive to illumination light (3). - At least a portion of the mask master (12) is projected onto the wafer (19) using the illumination exposure apparatus (1) as described in claim 10. - Develop a photosensitive layer exposed by the illumination light (3) on the wafer (19).

12. A component manufactured according to the method of claim 11.

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