Support structure for illumination optical unit of projection exposure apparatus

Abstract

An open-on-one side support structure (36) for an illumination optical unit (15) of a microlithographic projection exposure apparatus (1) has a frame (46) extending in a longitudinal direction (37), with one or more components for increasing the rigidity of the frame (46), with ribs (48) and / or planar reinforcing elements (47, 42, 43) acting as reinforcing components.

Description

[0001] The contents of German patent application DE 10 2023 208 965.3 are incorporated herein by reference. Technical Field

[0002] This invention relates to a support structure for an illumination optical unit in a projection exposure apparatus. It also relates to an illumination optical unit, illumination system, optical system, and projection exposure apparatus containing a corresponding support structure. Finally, this invention relates to a method for manufacturing microstructured or nanostructured components and a fabric manufactured according to this method. Background Technology

[0003] In a CRAO (Content-Related Amplitude Orientation) illumination system with a small principal beam angle at the object, the last optical component in the beam path upstream of the mask master is positioned near the separation plane between the illumination system and the projection optics unit. A support structure is typically provided for arranging the optical components. Due to the small distance relative to the separation plane, the mounting space available for the support structure is limited in at least one direction. Summary of the Invention

[0004] One object of the present invention is to improve the support structure of the illumination optical unit for projection exposure equipment.

[0005] This objective is achieved, in particular, through a support structure having the features for which protection is sought.

[0006] According to one aspect of the invention, the support structure has one or more members for increasing the stiffness of the frame. In particular, ribs, struts, and planar reinforcing elements are selected as reinforcing members. Partition walls (especially partitions) can also be used as reinforcing elements. It has been found, in particular, that a frame open on one side can be specifically reinforced by using surface stiffness and / or the configuration of ribs and / or struts. This ensures that the support structure meets increasing requirements, particularly in terms of its mechanical and dynamic performance. The support structure (especially the frame) can be configured in a manner that uses at least a first natural frequency greater than 100 Hz (especially greater than 200 Hz, especially at least greater than 400 Hz).

[0007] The following assumes that the projection optics and illumination optics of the projection exposure apparatus are substantially arranged in a non-intersecting half-space separated from each other by a separation plane. In this case, the separation plane may be specifically oriented perpendicular to the object plane in which the mask master is arranged. The separation plane may be specifically oriented parallel to the transverse scanning direction.

[0008] Hereinafter, the longitudinal direction will be considered as either parallel to the direction of the principal ray incident on the mask master or perpendicular to the object field. The longitudinal deviation from the normal to the object plane is typically at most 30 degrees, particularly 20 degrees, and especially at most 10 degrees.

[0009] This support structure is specifically designed for mounting optical components. It is particularly useful for spatially fixing optical components, especially within the illumination optics unit. Furthermore, the support structure can be adjusted relative to the reference system of the projection exposure apparatus.

[0010] Within the illumination optics unit, the support structure itself can form a reference system.

[0011] According to one aspect, the frame is at least partially open. In particular, the frame may be at least partially open on one side. It may be particularly open on the side facing the separation plane (especially in the lateral direction, that is, laterally relative to the longitudinal direction, and especially vertically).

[0012] The frame has a total range along the longitudinal direction, the size of which is at least equal to the size of its maximum range along the transverse direction, particularly at least 1.5 times, and especially at least 2 times, the size. This has proven useful for the configuration of various components of the illumination optics unit on the frame.

[0013] Ribs and / or reinforcing elements can be configured in profile shapes. Their cross-sections can be, in particular, T-shaped, H-shaped, C-shaped, V-shaped, or X-shaped. Therefore, stiffness along a specific direction can be further improved.

[0014] According to one aspect, the frame is opened to one side, particularly completely, in a transverse direction relative to the longitudinal direction, for more than 50% (especially at least 60%, especially at least 70%, especially at least 80%, especially at least 90%) of its longitudinal extent. The frame may be opened, in particular, in a direction perpendicular to the longitudinal direction.

[0015] The open side may in particular face the separation plane between the illumination optical unit and the projection optical unit.

[0016] In another aspect, the support structure has an outward-facing planar boundary wall on the side of the frame that faces outwards. This allows the support structure to be positioned as close as possible to the separation plane between the illumination optics unit and the projection optics unit. The separation plane can be located, in particular, in the free zone of the boundary wall.

[0017] According to another aspect, the frame may have at least a triangular, trapezoidal, or pentagonal cross-section in the transverse (particularly vertical) direction relative to the longitudinal direction. Typically, the frame may be configured in a polygonal form in the transverse (particularly vertical) cross-section relative to the longitudinal direction.

[0018] The support structure can be specifically configured such that the frame has a triangular cross-section at a first location along the longitudinal direction and a trapezoidal cross-section at a second location along the longitudinal direction.

[0019] Exceptionally high stiffness can be achieved through triangular and / or trapezoidal and / or pentagonal cross sections.

[0020] In this context, a trapezoid is understood, in particular, as a trapezoid that is neither rectangular nor parallelogram-shaped. Trapezoids especially have parallel bases of varying lengths. Therefore, shear tolerance can be reduced (and, in particular, avoided).

[0021] According to another aspect, the frame may be defined longitudinally by three or more triangular or trapezoidal reinforcing plates. In particular, the frame may be defined longitudinally by three triangular reinforcing plates.

[0022] The framework can have a minimum convex envelope defined only by the surfaces of triangles and quadrilaterals (especially trapezoids).

[0023] The frame can, in particular, have a minimum convex envelope in the shape of a pyramid. In this case, the base of the envelope can be configured as trapezoidal, non-rectangular, or rectangular. In particular, the base faces the separation plane. Specifically, the base can be oriented parallel to the separation plane.

[0024] The vertex of a pyramid can be located vertically above the boundary edge of its base.

[0025] The planar reinforcing elements (especially reinforcing plates) can be mounted tangentially on the frame.

[0026] The frame can be configured to have at least a C-shaped cross section.

[0027] According to another aspect, the frame may have a receiving portion at opposite ends along the longitudinal direction for receiving optical components. These optical components may in particular be faceted reflectors of an illumination optics unit.

[0028] Typically, the frame may have connection points for attachments. These attachments may be optical, mechanical, or electrical components (especially modules) of projection exposure equipment (particularly illumination optics units). In particular, the attachment may have its own attachment housing.

[0029] The accommodating of optical components and / or attachments (especially modules) within corresponding receptacles of the frame can further enhance the frame's rigidity. In particular, the rigidity of the optical components and / or attachments (especially their housings) can be utilized to strengthen the supporting structure.

[0030] The corresponding optical components and / or attachments can be fixedly or releasably connected to the frame. In particular, the optical components and / or attachments can be screwed, clamped, or welded to the frame. Various interlocking or force-locking connection techniques are preferred. However, integral joining is not excluded herein.

[0031] According to another aspect, one or more reinforcing elements may be configured inside the frame. These may be oriented parallel to the longitudinal direction, perpendicular to the longitudinal direction, or inclined relative to the longitudinal direction.

[0032] In particular, supports or plates can be used as reinforcing elements. Plates may have cuts. Cuts may be configured, in particular, in the form of conical cross sections, especially in parabolic or elliptical forms, and especially in circular forms.

[0033] A reinforcing element that is oriented laterally relative to the longitudinal direction is also called a transverse reinforcing element or transverse strengthening element.

[0034] A reinforcing element that is substantially parallel to the longitudinal orientation can be used as a separator between straight sections in the folded beam path (especially a narrow folded beam path) of an illumination optics unit.

[0035] One, two, three or more intermediate bases may be configured within the support structure, particularly within the frame. These can serve as lateral reinforcements.

[0036] The support structure can be specifically configured to define an interior that enables unobstructed radiation paths having individual straight sub-segments of at least 1 m in length in each case (particularly at least 1.5 m, particularly at least 2 m).

[0037] These sub-segments can be specifically configured such that they form a radiating conical region or a radiating truncated conical region between the central focal point on one side and the first optical element (particularly the first faceted mirror) on the other side, and / or between the first optical element (particularly the first faceted mirror) and the second optical element (particularly the second faceted mirror), and / or between the second optical element (particularly the second faceted mirror), the third optical element and / or the fourth optical element and / or the object field.

[0038] The principal ray angle and / or folding angle in the beam path of the illumination optics unit may be at most 10 degrees, at most 7 degrees, or at most 6 degrees.

[0039] It has been found that the support structure according to the invention can reduce costs and mass. Furthermore, it can reduce the requirements for manufacturing precision. The use of welded assemblies allows for greater design freedom. The proposed construction type with ribs and / or intermediate bases facilitates the separation of the support structure along said intermediate bases. These additionally provide the surfaces required for modular connections (threaded flange joints or welded joints). Such modularity is cost-effective because the original modules are smaller and can be manufactured more economically, and generally require less machining (and therefore less manufacturing cost and time) than in the case of large monolithic structures.

[0040] Due to the basic shape of a triangle, trapezoid, or polygon, mass reduction has been achieved, allowing for a smaller (and therefore lighter) support structure compared to conventional rectangular structure types.

[0041] A further object of the present invention is to improve the illumination optical unit, the illumination system, the optical system for the projection exposure device, and the projection exposure device.

[0042] These objectives are achieved by corresponding optical units / systems containing the aforementioned support structure.

[0043] According to one aspect, the support structure can be used to support at least one optical component. In particular, the support structure can be used to position one or two faceted mirrors in the beam path of the illumination optical unit. Due to the mechanical properties of the support structure, the optical components (especially the mirrors) can be positioned with particularly high precision. This should be understood as non-limiting when the following description of the arrangement of mirrors (especially faceted mirrors) on the support structure is presented. Corresponding statements may also apply to other optical components.

[0044] In particular, optical components (especially one or two faceted mirrors) can be configured on the frame of the support structure, and particularly connected to the frame. In particular, the two faceted mirrors can be configured opposite to each other on it. In particular, the two faceted mirrors can be connected to the frame at an end of the frame in each case.

[0045] The support structure is configured in the illumination optical unit, specifically in a manner that is open in the direction toward the separation plane of the projection optical unit.

[0046] The support structure can be located entirely in a half-space that faces away from the projection optical unit and is defined by a plane perpendicular to the object plane (particularly parallel to the cross-scan direction).

[0047] According to one aspect, the angle of the principal ray on the object can be up to 10 degrees, especially up to 7 degrees, and especially up to 6 degrees.

[0048] According to another aspect, the distance between the last optical element (in particular the last reflector, especially the second faceted reflector) in the beam path of the illumination radiation located upstream of the mask master and the plane defining the support structure toward the opening side can be up to 10 cm, particularly up to 5 cm, particularly up to 3 cm, particularly up to 2 cm, particularly up to 1 cm.

[0049] According to another aspect, the object-side numerical aperture can be at least 0.3, and in particular at least 0.5.

[0050] In addition to the aforementioned lighting optical unit, the lighting system also has a radiation source for generating lighting radiation, particularly an EUV radiation source. Specifically, the EUV radiation source can generate lighting radiation in the EUV range, with wavelengths particularly less than 30 nm, and particularly less than 15 nm.

[0051] The optical system includes an illumination optical unit as described above and a projection optical unit for transmitting illumination radiation from the object field to the image field.

[0052] In addition to the aforementioned illumination system, the projection exposure device also has a projection optics unit for transmitting illumination radiation from the object field to the image field.

[0053] This invention provides an improved method for manufacturing microstructure or nanostructure components using the aforementioned projection exposure equipment. The improved mechanical properties of this support structure enable more precise manufacturing of microstructure or nanostructure components.

[0054] According to this method, a mask master having the desired imaging structure is disposed in the object field of an illumination optics unit. The structure of the mask master is imaged onto a radiation-sensitive layer of a wafer disposed in the image field of a projection optics unit using illumination radiation (particularly in the EUV range). Further details of this method are available from prior art, such as WO 2019 / 174 996 A1, which is referenced herein. Attached Figure Description

[0055] Further advantages and details of the invention will become apparent from the description of exemplary embodiments with reference to the figures, wherein:

[0056] Figure 1 The schematic diagram illustrates the components and beam path of a projection exposure device;

[0057] Figure 2 The arrangement of optical components near the separating plane between the illumination optics unit and the projection optics unit is schematically shown;

[0058] Figure 3 An exemplary diagram schematically illustrates a support structure for an illumination optics unit;

[0059] Figure 4 Schematic illustration based on Figure 3 A top view of the supporting structure;

[0060] Figure 5 A schematic diagram illustrating the support structure of the illumination optics unit with a prominently displayed frame; and

[0061] Figure 6 Schematic illustration based on Figure 5 The frame view is used to clarify further details. Detailed Implementation

[0062] The microlithography projection exposure apparatus 1 is used to fabricate microstructured or nanostructured electronic semiconductor components. A light or radiation source 2 emits EUV radiation 3 with a wavelength range, for example, between 0.2 nm and 30 nm, particularly between 0.1 nm and 15 nm.

[0063] Figure 1 The main components of one of the projection exposure devices 1 are shown schematically.

[0064] Radiation source 2 is part of radiation source module. Starting from radiation source module, illumination and imaging light 3 passes through intermediate focal point 4 and is guided from that intermediate focal point through illumination optics unit 15 toward object field 11 of projection exposure device 1, in which photolithographic mask 12 is configured as a mask master of the object to be projected.

[0065] The illumination optical unit 15 includes a field plane mirror 16 and a second plane mirror, hereinafter referred to as the pupil plane mirror 17. Even if this mirror does not need to be positioned in the pupil plane, the functions of these mirrors correspond to those known in the prior art. Figure 1 The image is shown only schematically and without any associated EUV beam path.

[0066] After reflection at the field facet mirror 16, the EUV pencil-shaped light beam is incident on the pupil facet mirror 17. Depending on the ideal illumination through the projection exposure device 1, individual actuable sub-elements of the first optical element are assigned to sub-elements of the second optical element. Thus, the illumination light 3 is guided to sequentially predefine individual illumination angles along the illumination channel in each case via pairs of individual sub-elements containing the first and second optical elements. For control purposes, these sub-elements are individually tilted.

[0067] Via the pupil facet mirror 17, and if appropriate, via the downstream transmission optical unit (not shown), individual light portions are imaged onto the projection optical unit 19 of the projection exposure device 1 (also in...). Figure 1 (Illustrated schematically) Illumination or object field 11 in a mask master or object plane 18.

[0068] In another embodiment of the illumination optics unit 15, particularly when the entrance pupil of the projection optics unit 19 is positioned appropriately, the reflector of the transmission optics unit upstream of the object field 11 can be omitted, which results in a corresponding increase in the transmission rate of the projection exposure device 1 for the radiation beam used.

[0069] The mask master 12 for reflecting the radiation beam is positioned in the object plane 18 within the region of the object field 11. The mask master 12 is supported by a mask master carrier 20, which can be moved in a controlled manner by a mask master displacement actuator 21.

[0070] The projection optics unit 19 images the object field 11 onto the image field 22 in the image plane 23. During projection exposure, the wafer 24, which carries a photosensitive layer, is disposed in the image plane 23 and is exposed during projection exposure by the projection exposure apparatus 1. The wafer 24 is carried by a wafer carrier 25, which can be controlled to move by a wafer shift driver 26.

[0071] During projection exposure, both the mask master 12 and the wafer are scanned synchronously along the scanning direction by corresponding control of the mask master displacement driver 21 and the wafer displacement driver 26. During projection exposure, the wafer can be scanned along the x-direction at a scanning rate of 600 mm / s.

[0072] Figure 2 The mounting space conditions between the last optical element 31 in the beam path of the illumination optics unit 15 and the mask master 12 are illustrated schematically and by example.

[0073] The illumination radiation 3 has a principal ray direction 32. The principal ray direction can be characterized by the principal ray angle 33. The emission angle 33 is also called the principal ray angle incident on the object on the mask master 12.

[0074] Figure 2 The separation plane 34 between the illumination optics unit 15 and the projection optics unit 19 is schematically shown. The separation plane 34 may be oriented specifically perpendicular to the object plane 18.

[0075] The separation plane 34 defines a virtual separation between the half-space in which the illumination optical unit 15 is disposed and the half-space in which the projection optical unit 19 is disposed.

[0076] With a small beam angle of 33, the distance A between the last optical element 31 of the illumination optics unit 15 and the separation plane 34 is very small. Specifically, in addition to depending on the principal ray angle 33, the distance A also depends on the size of the last optical element 31 in the direction perpendicular to the separation plane 34, particularly its range.

[0077] Distance A is required for the optical manufacturing process and / or the module mechanism (not shown) surrounding the optical element 31.

[0078] For illustrative purposes only, Figure 2The beam 35 incident on the last optical element 31 is also shown. In particular, if the beam path in the illumination optics unit 15 is narrowly folded, the reduced installation space available in this regard leads to difficult requirements for the support structure 36 for supporting (i.e. positioning) the optical components of the illumination optics unit.

[0079] exist Figure 3 and Figure 4 The example shown is 36 of this support structure.

[0080] The support structure 36 is open on one side. It has a particular feature of an opening 38 extending longitudinally 37.

[0081] Thus, the longitudinal direction 37 can coincide with or be parallel to the normal plane 18.

[0082] The support structure 36 has a first receiving portion 39 for receiving the first optical element. The first receiving portion is Figure 3 The upper housing portion. This should be considered non-limiting. The support structure 36 can also be configured in different orientations within the projection exposure device 1.

[0083] The first optical element, which can be configured in the first receiving portion 39, may be, in particular, a first faceted mirror, especially a field faceted mirror 16. The first optical element is received in the first receiving portion 39 in a manner connected to the support structure 36 (in particular, fixed or via a compensation element). The compensation element may be used, for example, to compensate for thermal expansion of the optical element or to dynamically decouple or set (adjust). In particular, the optical element or the compensation element may be screwed, clamped, or welded to the support structure 36.

[0084] At opposite ends along the longitudinal direction 37, the support structure has a second receiving portion 40. The second receiving portion 40 is used to receive a second optical element. The second optical element may be a second mirror, particularly a second faceted mirror, especially a pupil faceted mirror 17.

[0085] exist Figure 4 Open area 41 can be seen in the middle. Through open area 41, illumination radiation 3 is transmitted from the last optical element 31 of illumination optical unit 15 to object field 11.

[0086] Multiple lateral stiffeners 42 are disposed in the support structure 36. In particular, stiffening plates may be used as lateral stiffeners 42. Each of the stiffening plates may have a cutout 45 through which the lighting radiation 3 is blocked.

[0087] Each of the cuts 45 can be configured as an ellipse, particularly a circle.

[0088] Longitudinal stiffener 43 is configured within the support structure 36. A stiffening plate serves as the longitudinal stiffener 43. Cutouts allowing EUV radiation 3 to pass through can be provided for longitudinal stiffening. Figure 3As illustrated in the diagram and examples, the cutout 44 in the longitudinal reinforcement 43 can be arranged in a parabolic manner.

[0089] The support structure 36 essentially surrounds the beam path of the illumination optical unit 15 in the shape of the letter C. Therefore, the support structure 36 is configured as an open structure on one side.

[0090] The support structure 36 has a planar boundary wall 49 facing the open side. The free surface of the boundary wall 49 may coincide with the separation plane 34. It is generally preferred to be oriented parallel to the separation plane 34.

[0091] The support structure 36 can be configured (especially fixed) on the support member in the projection exposure device 1 via the lateral protrusion 50.

[0092] To increase the stiffness (especially torsional stiffness) of the support structure 36, the support structure may have a frame 46. Figure 5 The example in the text highlights frame 46. Figure 5 and Figure 6 It is shown purely illustratively.

[0093] The frame 46 can be further reinforced by ribs 48. In this way, ribs 48 can form the shaped ribs of the frame 46. An outer skin (in particular in the form of a reinforcing plate 47) can then be applied to the ribs.

[0094] The frame 40, with ribs 48 and / or reinforcing plates 47, allows (particularly due to its regular structure) the manufacture of small sub-sections that can be connected to form a complete support structure 36. This reduces costs and the necessary manufacturing precision.

[0095] Due to the triangular and / or trapezoidal cross sections, especially the rib types combined with the construction, it is possible to reduce mass and volume, thus also reducing the degree of machining compared to support structures with rectangular cross sections.

[0096] The support structure 36 can be configured as a welded assembly. This provides greater design freedom due to the advantageous segmentation.

[0097] Furthermore, smaller raw material segments are easier to obtain, produce, and manage in terms of material quality and uniformity.

Claims

1. A support structure (36) for an illumination optical unit (15) of a microlithography projection exposure apparatus (1), comprising: 1.1 The frame (46) extends along the longitudinal direction (37). 1.1.1 Wherein the frame only partially surrounds a radial cross-sectional region in a plane perpendicular to the longitudinal direction (37); and 1.2 One or more components for increasing the stiffness of the frame (46), wherein the one or more components are selected from the following list: ribs (48), struts, planar stiffeners (47, 42, 43).

2. The support structure (36) as described in claim 1, characterized in that, The frame (46) is open to one side in the transverse direction relative to the longitudinal direction (37) for at least 50% of its extension along the longitudinal direction (37).

3. The support structure (36) as described in claim 2, characterized in that, The supporting structure has an outward planar boundary wall (49) on the side of the frame (46) facing its open side.

4. The support structure (36) as described in any of the preceding claims, characterized in that, The frame (46) has at least a triangular, trapezoidal or pentagonal cross section in the transverse direction relative to the longitudinal direction (37).

5. The support structure (36) as described in any one of the preceding claims, characterized in that, The frame (46) is defined in the longitudinal direction (37) by at least one triangular or trapezoidal reinforcing element (47).

6. The support structure (36) as described in any of the preceding claims, characterized in that, The frame (46) is defined outward by three or four planar reinforcing elements (47) that are essentially triangular.

7. The support structure (36) as described in any of the preceding claims, characterized in that, The frame (46) has a receiving portion (39, 40) for receiving optical components at opposite ends in the longitudinal direction (37).

8. The support structure (36) as described in any of the preceding claims, characterized in that, One or more planar reinforcing elements (42, 43) are disposed inside the frame (46).

9. An illumination optical unit (15) for a microlithography projection exposure apparatus (1), comprising: 9.1 The support structure (36) as described in any of the preceding claims; and 9.2 At least one optical component is supported by the support structure (36).

10. The illumination optical unit (15) as claimed in claim 9, characterized in that, The principal ray angle (CRAO) on an object is at most 10 degrees.

11. The illumination optical unit (15) as described in claim 9 or 10, characterized in that, The distance A between the last optical element (31) in the beam path upstream of the mask master (12) and the plane (34) that defines the support structure (36) toward the open side is at most 15 cm.

12. The illumination optical unit as claimed in any one of claims 9 to 11, characterized in that, The object-side numerical aperture (NAO) is at least 0.

3.

13. An illumination system for a microlithography projection exposure apparatus (1), comprising: 13.1 The illumination optical unit (15) as described in any one of claims 9 to 12; as well as 13.2 Radiation source (2) for generating lighting radiation (3).

14. An optical system for a microlithography projection exposure apparatus (1), comprising: 14.1 The illumination optical unit (15) as described in any one of claims 9 to 12; as well as 14.2 Projection optical unit (19) for transferring illumination radiation (3) from object field (11) to image field (22).

15. A microlithography projection exposure device (1). include: 15.1 The lighting system as claimed in claim 13; and 15.2 Projection optical unit (19) for transferring illumination radiation (3) from object field (11) to image field (22).

16. A method for manufacturing microstructured or nanostructured components, Includes the following steps: 16.1 Provide a microlithography projection exposure apparatus (1) as described in claim 15; 16.2 Set a mask master (12) with the structure to be imaged in the object field (11); and 16.3 The structure to be imaged is imaged onto the illumination-sensitive layer of the wafer (24) disposed in the image field (22).

17. A microstructure or nanostructure component manufactured by the method of claim 16.

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