Measurement device

Abstract

There is provided a metrology apparatus for a lithographic system, the metrology apparatus comprising: a plurality of independently movable fingers configured to control a shape of an illuminated region of a patterning device, where one or more of the independently movable fingers comprise one or more reflective surfaces; and one or more radiation sensors; wherein the one or more reflective surfaces of the one or more independently movable fingers are configured to reflect radiation toward the one or more radiation sensors.

Description

Cross Reference to Related Applications

[0001] This application claims priority to EP application 23184404.4, filed on 10 July 2023, which is incorporated herein in its entirety by reference. TECHNICAL FIELD

[0002] The present invention relates to a metrology apparatus that can be suitable for use in a lithographic system. The lithographic system can be an extreme ultraviolet (EUV) lithographic system comprising a lithographic apparatus. BACKGROUND

[0003] A lithographic apparatus is a machine constructed to apply a desired pattern onto a substrate. The lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). The lithographic apparatus can, for example, project a pattern from a patterning device (for example, a mask) onto a layer of radiation-sensitive material (resist) provided on a substrate.

[0004] To project the pattern onto the substrate, the lithographic apparatus can use electromagnetic radiation. A wavelength of the radiation decides a minimum size of features which can be formed on the substrate. A lithographic apparatus using extreme ultraviolet (EUV) radiation, having a wavelength within a range of 4-20 nm, for example 6.7 nm or 13.5 nm, can be used to form smaller features than a lithographic apparatus using, for example, radiation with a wavelength of 193 nm.

[0005] A patterning device (for example, a reticle) in a lithographic apparatus that is used to impart the pattern to the beam of radiation can form part of a mask assembly. Independently movable fingers can be used to define a region of the patterning device that receives radiation.

[0006] Characteristics of the EUV radiation and / or characteristics of the lithographic apparatus can have an influence on the projection of the pattern. The lithographic apparatus typically includes a dedicated sensor (for example, a dose sensor) for measuring these characteristics.

[0007] The projection of the pattern onto a layer of radiation-sensitive material (resist) provided on a substrate can be referred to as an exposure. Typically, during exposure of a substrate, it can be difficult or impossible to measure the radiation and / or one or more characteristics of the lithographic apparatus using the dedicated sensor. Other characteristics can be measured in a limited manner during exposure of a substrate.

[0008] It can be desirable to provide an apparatus that obviates or mitigates one or more problems associated with the prior art. SUMMARY

[0009] According to a first aspect, there is provided a metrology apparatus for a lithographic system, the metrology apparatus comprising: a plurality of independently movable fingers configured to control a shape of an illuminated area of a patterning device, wherein one or more of the independently movable fingers comprises one or more reflective surfaces; and one or more radiation sensors; wherein the one or more reflective surfaces of the one or more independently movable fingers are configured to reflect radiation towards the one or more radiation sensors.

[0010] The term reflect is to be taken to indicate a reflection of a majority, but not the total proportion of incident light. For example, a surface reflecting 60% of the incident intensity can be described as reflecting.

[0011] The one or more reflective surfaces can be configured to reflect at least 60% of light incident on the independently movable finger.

[0012] Advantageously, providing reflective surfaces allows some of the incident radiation that would otherwise be absorbed to be utilised. This allows the radiation beam characteristics of the lithographic system (and in extension the state of the lithographic system itself) to be determined without affecting the exposure of the substrate. Furthermore, reflecting incident radiation from the independently movable fingers reduces their power absorption, thereby avoiding excessive thermal distortion.

[0013] The one or more radiation sensors can be intensity sensors.

[0014] The one or more radiation sensors can be imaging sensors.

[0015] The imaging sensors can be cameras.

[0016] The one or more radiation sensors can be arranged in one or more arrays.

[0017] The one or more reflective surfaces comprise one or more angled reflective surfaces configured to reflect radiation in a direction substantially parallel to the patterning device.

[0018] At least one of the one or more reflective surfaces can have an angle relative to a normal direction of the patterning device of between 30° and 60°.

[0019] The one or more radiation sensors can be positioned to receive radiation in a direction substantially parallel to the patterning device.

[0020] The one or more reflective surfaces can comprise one or more reflective surfaces substantially parallel to the patterning device.

[0021] The one or more radiation sensors may be positioned to receive radiation reflected from one or more reflective surfaces substantially parallel to the pattern forming apparatus.

[0022] The term substantially or substantially parallel to the pattern forming apparatus should be understood to include: radiation propagating between 0° and 15° relative to the pattern forming apparatus.

[0023] The one or more reflective surfaces may include a multilayer structure. The multilayer structure may be a Mo-Si multilayer.

[0024] At least one of the one or more reflective surfaces may be concave.

[0025] The measuring device may also include separate optical elements configured to modulate radiation reflected from the one or more reflective surfaces. The separate optical elements may include reflective elements.

[0026] According to a second aspect, a photolithography system is provided including a measurement apparatus according to the first aspect, wherein the photolithography system further includes: a radiation source; an irradiation system configured to adjust a radiation beam; and a support structure configured to support a pattern forming apparatus capable of imparting a pattern to the radiation beam in a cross-section of the radiation beam to form a patterned radiation beam. The measurement apparatus may include any of the optional features described above.

[0027] According to a third aspect, a method for controlling a lithography system is provided, the lithography system comprising: a radiation source; an irradiation system configured to adjust a radiation beam; and a support structure configured to support a patterning apparatus capable of patterning the radiation beam in a cross-section of the radiation beam to form a patterned radiation beam; a measurement device comprising: a plurality of independently movable fingers configured to control the shape of an irradiated area of ​​the patterning apparatus, wherein one or more of the independently movable fingers include one or more reflective surfaces; and one or more radiation sensors; wherein the one or more reflective surfaces of the one or more independently movable fingers are configured to reflect radiation toward the one or more radiation sensors; wherein the method comprises: measuring characteristics of the reflected radiation using the one or more radiation sensors; determining characteristics of the radiation beam based on the measured characteristics of the reflected radiation; and changing the state of the lithography system in response to the characteristics of the radiation beam.

[0028] Changing the state of the lithography system may include moving one or more of the independently movable fingers.

[0029] Changing the state of the lithography system includes changing the configuration of one or more optical elements of the irradiation system or the configuration of the radiation source.

[0030] The characteristics of the radiation beam can be angular intensity distribution and / or spatial intensity distribution. Attached Figure Description

[0031] Embodiments of the invention will now be described by way of example only with reference to the accompanying illustrative drawings, in which: - Figure 1 A lithography system, including lithography equipment and a radiation source, is described; Figure 2 depicts Figure 2A It is set at the first end position. Figure 1 The diagram shows a schematic plan view of the support structure and pattern forming apparatus of the photolithography equipment. - Figure 2B It is located at the second end position. Figure 1 A schematic plan view of the support structure and pattern forming apparatus shown in the figure; - Figure 3A yes Figure 1 A schematic diagram of the first cross-section of the pattern forming device and the mask shielding plate on the support structure of the lithography equipment; - Figure 3B yes Figure 1 A schematic diagram of the second cross-section of the pattern forming device and the mask shielding plate on the support structure of the lithography equipment; - Figure 4 It is shown that the first configuration is presented Figure 1 A plan view of the y-mask and x-mask (dashed lines) of a lithography equipment; - Figure 5 This is a schematic diagram of a measuring device according to an embodiment of the present disclosure; - Figure 6 It is based on Figure 5 A schematic illustration of a portion of the measuring device in an embodiment; and - Figure 7 This is a schematic illustration of a method for controlling a photolithography system according to an embodiment of the present disclosure. Detailed Implementation

[0032] Figure 1 A lithography system including a radiation source SO and a lithography apparatus LA is shown. The radiation source SO is configured to generate an EUV radiation beam B and provide the EUV radiation beam B to the lithography apparatus LA. The lithography apparatus LA includes an irradiation system IL, a support structure MT configured to support a patterning apparatus MA (e.g., a mask), a projection system PS, and a substrate stage WT configured to support a substrate W. The lithography apparatus LA also includes a measurement device 50 located near the patterning apparatus MA.

[0033] The irradiation system IL is configured to adjust the EUV radiation beam B before it is incident on the pattern forming apparatus MA. Thus, the irradiation system IL may include a faceted field mirror assembly 10 and a faceted pupil mirror assembly 11. Together, the faceted field mirror assembly 10 and the faceted pupil mirror assembly 11 provide the EUV radiation beam B with a desired cross-sectional shape and a desired intensity distribution. The irradiation system IL may include other mirrors or devices besides or replacing the faceted field mirror assembly 10 and the faceted pupil mirror assembly 11.

[0034] The faceted field mirror assembly 10 and the faceted pupil mirror assembly include multiple independently controllable mirror facets. The faceted field mirror 10 is configured to project a spot of EUV radiation onto the mirror facets of the faceted pupil mirror assembly. The orientation of the mirror facets of the faceted pupil mirror assembly 11 defines the angle at which radiation propagates to the patterning apparatus MA. The intensity of the spot on each mirror facet determines the radiation intensity propagating at each angle. The angular intensity distribution of the EUV radiation beam B at the patterning apparatus MA can significantly affect the imaging performance of the lithography equipment LA.

[0035] After this adjustment, the EUV radiation beam B interacts with the patterning apparatus MA. This interaction produces a patterned EUV radiation beam B'. A projection system PS is configured to project the patterned EUV radiation beam B' onto a substrate W. For this purpose, the projection system PS may include a plurality of mirrors 13, 14 configured to project the patterned EUV radiation beam B' onto the substrate W held by the substrate stage WT. The projection system PS may apply a reduction factor to the patterned EUV radiation beam B' to form an image with features smaller than the corresponding features on the patterning apparatus MA. For example, a reduction factor of 4 or 8 may be applied. Although in Figure 1 The projection system PS shown has only two mirrors 13 and 14, but the projection system PS may include a different number of mirrors (e.g., six or eight mirrors).

[0036] The substrate W may include a previously formed pattern. In this case, the photolithography apparatus LA aligns the image formed by the patterned EUV radiation beam B' with the pattern previously formed on the substrate W. The substrate W may be a wafer.

[0037] A relative vacuum, i.e., a small amount of gas (e.g., hydrogen) at a pressure much lower than atmospheric pressure, can be provided in the radiation source SO, the irradiation system IL, and / or the projection system PS.

[0038] The radiation source SO can be a laser-generated plasma (LPP) source, a discharge-generated plasma (DPP) source, a free-electron laser (FEL), or any other radiation source capable of generating EUV radiation.

[0039] Now for reference Figures 2A to 4 Descriptions are provided of some additional features of the lithography apparatus LA of the example type (in particular, some features and components close to the support structure MT).

[0040] In one example, the pattern forming device MA can be a mask.

[0041] The support structure MT can move in the scanning direction to expose a larger area of ​​the pattern forming apparatus MA in a single dynamic scan exposure, as now referenced. Figure 2A and Figure 2B The discussion. Figure 2A and Figure 2B A schematic plan view of the support structure MT and the mask 15 located in two different positions is shown.

[0042] A support structure MT is movably mounted within region 24. The lithography apparatus LA can be considered to include a scanning module operable to move the support structure MT relative to the support frame within region 24. Specifically, the support structure MT can be positioned along the scanning direction (as indicated by arrow 26) at a first end position (e.g., at...). Figure 2A (as shown in) and the second end position (as in) Figure 2B (as shown in the image) move between.

[0043] Unless otherwise illustrated, the following Cartesian coordinate set will be used throughout this specification. The scanning direction is denoted as the y-direction. The direction also in the plane of the support structure MT and perpendicular to the scanning direction is referred to as the non-scanning direction, and this direction is denoted as the x-direction. The normal direction of the plane of the support structure MT is denoted as the z-direction.

[0044] The photolithography apparatus LA is equipped with four masking plates that define the extent of the irradiated field on the substrate W, as now referenced. Figure 3A , Figure 3B and Figure 4As described. When the irradiation system IL is mounted on the support structure MT, the irradiation system IL is operable to irradiate a region of the pattern forming apparatus MA. This region may be referred to as a slit of the irradiation system IL and is at least partially defined by four masking plates that define a generally rectangular area of ​​the pattern forming apparatus capable of receiving radiation. The extent of this generally rectangular area in a first direction (which may be referred to as the x-direction) is defined by a pair of x-masks 32, 34. The extent of the generally rectangular area in a second direction (which may be referred to as the y-direction) is defined by a pair of y-masks 36, 38.

[0045] Each of the shielding plates 32, 34, 36, and 38 is positioned adjacent to, but outside of, the plane of the pattern forming apparatus on the support structure MT. The x-shielding plates 32 and 34 are positioned in the first plane 40, and the y-shielding plates 36 and 38 are positioned in the second plane 42.

[0046] Each of the shielding plates 32, 34, 36, and 38 defines one edge of a rectangular field region 44 in the plane of the pattern forming apparatus MA that can receive radiation. In practice, the illumination system IL can illuminate only a portion of the rectangular field region 44. (As in...) Figure 4 As shown, the irradiation system IL can be arranged to irradiate a curved slit region 46, which can overlap with a portion of a rectangular field region 44 (depending on the position of the y-shielding plates 36, 38).

[0047] The curved slit region 46 is partially defined by optics within the illumination system IL. Additionally, the curved slit region 46 is partially defined by a plurality of independently movable fingers 47 disposed along one or both curved edges of the curved edge of the curved slit region 46. These plurality of independently movable fingers 47 may be referred to as unicom fingers. The plurality of independently movable fingers 47 are positioned adjacent to shielding plates 32, 34, 36, and 38, such that the shielding plates are positioned between the plurality of independently movable fingers and the pattern forming apparatus MA. The plurality of independently movable fingers 47 may be positioned at different x-positions and are movable in the y-direction to selectively block portions of the radiation beam B generated by the illumination system IL. Controlling the y-position of the movable fingers 47 controls the shape of one or both curved edges of the curved edge of the curved slit region 46. For a given scan rate, the extent of the curved slit region 46 in the scan direction (y-direction) determines the exposure duration at any x-position along the mask 15. The exposure duration, combined with the incident intensity, determines the dose received at any point on the mask 15 and at its conjugate image plane (substrate W). Movable fingers 47 can be used to minimize variations in the radiation dose provided by the radiation beam B at different locations in the non-scanning direction (x-direction). The dose variation in the non-scanning direction is expressed with reference to a parameter known as slit uniformity. Maintaining high slit uniformity is desirable to preserve the optimal performance of the lithography apparatus LA.

[0048] Additionally, the curved slit region 46 may be partially defined by a physical aperture, such as the inlet aperture of the projection system PS.

[0049] Each of the shielding plates 32, 34, 36, and 38 can move independently between a retracted position and an inserted position. In the retracted position, each of the shielding plates 32, 34, 36, and 38 is not positioned in the path of the radiation beam, and in the inserted position, each of the shielding plates 32, 34, 36, and 38 at least partially blocks the radiation beam projected by the irradiation system IL onto the pattern forming apparatus MA. By moving the shielding plates 32, 34, 36, and 38 into the path of the radiation beam, the radiation beam B can be truncated (in the x-direction and / or y-direction), thereby limiting the range of the field region 44 receiving the radiation beam B.

[0050] The x-direction corresponds to the non-scanning direction of the lithography apparatus LA, and the y-direction corresponds to the scanning direction of the lithography apparatus LA. The pattern forming apparatus MA can move through the field region 44 in the y-direction (as indicated again by arrow 26) to expose the entire pattern forming apparatus MA in a single dynamic scan exposure.

[0051] During dynamic exposure of the target area of ​​substrate W, the target area moves through the exposure area. This exposure area is the region in the plane of substrate W that intersects with the radiation beam projected by the irradiation system IL. As the target area of ​​substrate W moves into the exposure area, the first shielding plates 36, 38 move such that only the target area receives radiation (i.e., any part of the substrate outside the target area is not exposed). At the start of the scan exposure, one of the y-shielding plates 36, 38 is positioned in the path of the radiation beam B as a baffle, preventing any part of substrate W from receiving radiation. At the end of the scan exposure, the other y-shielding plate 36, 38 is positioned in the path of the radiation beam B as a baffle, preventing any part of substrate W from receiving radiation. During the middle portion of the scan exposure, when there is no overlap between the exposure area 44 (which receives radiation B) and any adjacent target area of ​​substrate W, both y-shielding plates 36, 38 are positioned in a retracted position.

[0052] The rays of radiation beam B are shown adjacent to each of the shielding plates 32, 34, 36, and 38. It will be understood that each point in the slit region 46 is illuminated with radiation from a range of angles. For example, each point in the slit region 46 may receive a radiation cone. The rays of radiation beam B shown adjacent to each of the shielding plates 32, 34, 36, and 38 indicate the average direction of the radiation received by the pattern forming apparatus MA. The rays of radiation beam B shown adjacent to each of the shielding plates 32, 34, 36, and 38 may be referred to as the main rays. Figure 3A and Figure 3B As can be seen, in this embodiment, when projected onto the xz plane, the main ray of radiation is normally incident on the pattern forming apparatus MA; however, when projected onto the yz plane, the main ray of radiation is normally incident on the pattern forming apparatus MA at an angle of 48°.

[0053] In the following description, where multiple instances of the same component exist, only the selected instance is labeled in the diagram for clarity.

[0054] Figure 5 The measurement apparatus 50 of a photolithography system is schematically illustrated. The measurement apparatus includes a plurality of independently movable fingers 47, each of which includes a first reflective surface 52 and a second reflective surface 54. The measurement apparatus 50 also includes a plurality of radiation sensors. The first reflective surfaces 52 of each of the independently movable fingers 47 are each configured to reflect radiation toward one of the plurality of first radiation sensors 56. The second reflective surfaces 54 of each of the independently movable fingers 47 are each configured to reflect radiation toward one of the plurality of second radiation sensors 58.

[0055] The first reflective surface 52 and the second reflective surface 54 can be configured to reflect at least 60% of the light incident on the first and second reflective surfaces of the independently movable finger.

[0056] Each independently movable finger 47 and its associated first and second sensors can be collectively referred to as a measurement system unit.

[0057] Multiple first radiation sensors 56 and multiple second radiation sensors 58 may be arranged in a first sensor array and a second sensor array, respectively. In some embodiments, both the first radiation sensor 56 and the second radiation sensor 58 may be intensity sensors.

[0058] For example, the plurality of first radiation sensors 56 and the plurality of second radiation sensors 58 may include photodiodes. Alternatively, the plurality of first radiation sensors 56 and the plurality of second radiation sensors 58 may include a water-cooled beam collector for calorimetric monitoring.

[0059] In other embodiments, a plurality of second radiation sensors 58 may additionally or alternatively include an imaging sensor (such as a camera). Typically, the first and second radiation sensors can be any type of radiation sensor.

[0060] Figure 6 The diagram illustrates a measurement system unit of a measurement system 50, in situ with selected components of the illumination system IL of a lithography apparatus LA. The measurement system unit includes an independently movable finger 47, a first radiation sensor 56, and a second radiation sensor 58. A first reflective surface 52 is substantially parallel to a mask 15. A second reflective surface 54 is angled or tilted such that it reflects incident radiation toward the second radiation sensor 58 (e.g., along a direction substantially parallel to the mask 15). The angle of the second reflective surface 54 can be selected based on the orientation and / or position of the independently movable finger 47 relative to other optics of the illumination system IL (e.g., faceted pupil mirror assembly 11) and the second radiation sensor 58. The relative positions and orientations of the second reflective surface 54, other optics of the illumination system IL (e.g., faceted pupil mirror assembly 11), and the second radiation sensor 58 can vary between different embodiments. The angle of the second reflective surface 54 relative to the xz plane can be between 30° and 60°.

[0061] In use, EUV radiation beam B (see...) Figure 1 The reflection from the faceted pupil reflector device 11 to the grazing incidence reflector 62 ( Figure 1 (Not shown in the image). EUV radiation beams consist of radiation propagating in various directions. Figure 6The selected rays of radiation beam B are shown in Figure 68. A first portion of the radiation is incident on the first reflective surface 52 and reflected onto the first sensor 56, as shown in ray 68. A second portion of the radiation is incident on the second reflective surface 54 and reflected onto the second sensor 58, as shown in ray 70. The remaining portions of the radiation are reflected from the grazing incidence mirror 62 onto the mask 15, such as image forming rays 64 and 66. The reflection intensities of the first and second portions of the radiation are measured by the first radiation sensor 56 and the second radiation sensor 58, respectively.

[0062] The second radiation sensor 58 can be integrated into a sleeve 63, which is a pre-existing structure associated with an independently movable finger 47. This avoids using additional space within the irradiation system IL.

[0063] Advantageously, the measurement device 50 allows the use of incident radiation that would otherwise be completely absorbed (if conventional absorbent, independently movable fingers 47 are used). This allows the determination of multiple radiation beam characteristics of the lithography system during the substrate exposure process (and, in the case of extension, the determination of the state of the lithography system itself).

[0064] Conventional absorptive, independently movable fingers absorb radiation and undergo thermal deformation. This thermal deformation can interfere with the mechanical operation of components and negatively impact the imaging performance of lithography equipment. Reflection of incident radiation by independently movable fingers reduces the power they absorb, thereby minimizing thermal deformation that could interfere with their mechanical operation and affect imaging performance.

[0065] Despite Figure 5 or Figure 6 Not illustrated, but the measuring device may include an actuation system configured to change the position of the first radiation sensor 56 and the second radiation sensor 58. The first radiation sensor 56 and the second radiation sensor 58 may be repositioned by actuation in response to the optical configuration of the illumination system IL and / or the position of the independently movable fingers 47, in order to receive reflected radiation from the first reflective surface 52 and / or the second reflective surface 54. The second radiation sensor 58 may have reduced actuation requirements. In some embodiments, the second radiation sensor 58 may be configured without an actuator. Light reflected by the second reflective surface 54 may be directed toward the second radiation sensor 58 regardless of the y-position of each independently movable finger 47.

[0066] The reflective surfaces 52 and 54 may include a multilayer structure, such as a Mo-Si multilayer.

[0067] The intensity measured by the first radiation sensor 56 and the second radiation sensor 58 of each measurement system unit indicates the radiation intensity at the x-position of each corresponding measurement system unit. In other words, the above-described measurement device provides slit intensity measurement with a resolution corresponding to the pitch of the independently movable fingers 47. By comparing the intensity at each x-position, the intensity distribution along the x-axis and the slit uniformity of the curved slit region 46 can be inferred. It can be deduced that, by utilizing the non-imaging portion of the EUV radiation beam, slit uniformity can be measured in real time during exposure of the substrate W.

[0068] Furthermore, the above intensity measurement results can be used to obtain real-time dose measurement results.

[0069] In some embodiments, the second sensor 58 may additionally or alternatively include an imaging sensor, such as a camera. These imaging sensors can be used to reconstruct at least a partial image of the light pattern on the faceted pupil reflector assembly 11 (i.e., the distribution of spots on the reflector facet 63). The intensity pattern on the faceted pupil reflector assembly 11, combined with knowledge of the configuration of the faceted pupil reflector assembly, provides information about the angular and spatial intensity distribution of the EUV radiation beam incident on the mask 15 at the location of each independently movable finger 47 along the x-axis in the curved slit region 46. Specific angular and spatial intensity distributions of the light can be crucial for maintaining imaging performance.

[0070] Furthermore, tracking the positions of individual spots on the mirror facet 63 of the faceted pupil reflector assembly 11 can be used to measure the alignment drift of optical elements in the illumination system IL. For example, the alignment drift of individual facet fields of the faceted field assembly 10, as well as the alignment drift of the entire faceted field assembly 10, can be measured. Global alignment drift, such as the alignment drift between the illumination system IL and the source SO, can also be detected.

[0071] To image the faceted pupil reflector assembly 11, the measuring device may also include a separate optical element configured to modulate radiation reflected from one or more reflective surfaces. This separate optical element may include reflective elements, such as reflective multilayers.

[0072] Additionally or alternatively, in some embodiments, the second reflective surface 54 may be flat, concave, or convex to form an image at the second radiation sensor 58. In embodiments where the second reflective surface 54 is flat and / or convex, additional optics (e.g., mirrors) may be required to focus onto the sensor(s). Additional optics are also required if a direct line of sight between the sensor and the first reflective surface 52 and the second reflective surface 54 may not be necessary.

[0073] Furthermore, in some embodiments, the independently movable finger 47 and the second radiation sensor 58 can be coupled with... Figure 6 The configurations shown are oriented differently. In one example, the independently movable finger 47 and the second radiation sensor 58 can be flipped so that the independently movable finger 47 is adjacent to the y-shielding plate 38.

[0074] Although reference Figure 5 and Figure 6 The described measuring device 50 includes a plurality of first radiation sensors 56 and a plurality of second radiation sensors 58, but in some embodiments, a single radiation sensor or any number of radiation sensors may be present. Multiple reflective surfaces may reflect radiation toward a single radiation sensor. Alternatively, each reflective surface may reflect radiation toward multiple radiation sensors.

[0075] Information collected by measurement equipment regarding optical alignment and slit strength can be used to inform the control of the lithography system. Figure 7 A method 100 for controlling a photolithography apparatus is schematically illustrated. (Refer to...) Figure 5 and Figure 6 The method is described using embodiments, but is not limited to its application in a single embodiment. Method 100 can be performed at least in part by a controller including a processor.

[0076] In step S1, the characteristics of reflected radiation are measured using a radiation sensor. The reflected radiation can be reflected from either the first reflective surface 52 or the second reflective surface 54, and is measured by either the first radiation sensor 56 or the second radiation sensor 58, respectively.

[0077] In step S2, the characteristics of radiation beam B are determined based on the measured characteristics of the reflected radiation. The characteristics of radiation beam B include the angular intensity distribution and / or spatial intensity distribution of the radiation beam, slit uniformity, and beam alignment characteristics.

[0078] At decision D1, the characteristics of the radiation beam obtained in step S3 are compared with the desired reference state. If the measured characteristics of the radiation beam deviate sufficiently from the desired reference state, the method proceeds to step S3. If the measured characteristics of the radiation beam are sufficiently close to the desired reference state, the method returns to step S1.

[0079] In step S3, the state of the lithography system is changed in response to the characteristics of the radiation beam B. The state of the lithography system is changed to correct or reduce deviations from the desired reference state.

[0080] The characteristics of the radiation beam can include the slit intensity at each x position and its variation, from which slit uniformity can be calculated. If the slit uniformity deviates from the desired reference state (i.e., the slit uniformity is insufficient), changing the state of the lithography system can include moving one or more of the independently movable fingers 47 to correct for non-uniform illumination of the substrate W.

[0081] The characteristics of the radiation beam may include angular intensity distribution and / or spatial intensity distribution. If the angular intensity distribution and / or spatial intensity distribution of the radiation beam deviates from the desired reference state (e.g., a non-optimal propagation angle), changing the state of the lithography system may include changing the configuration of one or more optical elements of the irradiation system IL and / or the configuration of the radiation source SO (e.g., source plasma position). The configuration of one or more optical elements of the irradiation system may include the orientation of the mirror facets of the faceted field mirror 10.

[0082] The spatial intensity distribution of the radiation beam can also indicate alignment drift between multiple optical components. For example, the alignment between the source SO and the illumination system IL.

[0083] Optionally, the method may also include a calibration step. In one example, prior to substrate exposure, the characteristics of the radiation beam, determined based on the measured characteristics of the reflected radiation, can be compared with the same characteristics measured by other sensors, such as a dose sensor, a wafer-level alignment sensor, and a wafer-level pupil camera. Some calibration measurement comparisons can be performed less frequently than others (e.g., every few days).

[0084] It should be understood that in some embodiments, one or more of these steps may occur in parallel with other steps. In one example, method 100 may be implemented as an open-loop control scheme, a closed-loop feedback control scheme, or a feedforward control scheme.

[0085] While this article provides specific references to the use of lithography equipment in IC manufacturing, it will be understood that the lithography equipment described herein can have other applications. Other potential applications include manufacturing integrated optical systems, guiding and detecting patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin-film magnetic heads, etc.

[0086] Although embodiments of the invention may be specifically referred to herein in the context of lithography equipment, embodiments of the invention can be used in other equipment. Embodiments of the invention can form part of mask inspection equipment, metrology equipment, or any equipment that measures or processes objects such as wafers (or other substrates) or masks (or other patterning apparatus). These devices are generally referred to as lithography tools. Such lithography tools can use vacuum conditions or ambient (non-vacuum) conditions.

[0087] Where circumstances permit, embodiments of the invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the invention may also be implemented by instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any means for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read-only memory (ROM); random access memory (RAM); magnetic storage media; optical memory media; flash memory devices; electrical, optical, acoustic, or other forms of propagation signals (e.g., carrier waves, infrared signals, digital signals, etc.), and so on. Furthermore, firmware, software, routines, and instructions may be described in this invention as performing certain actions. However, it should be understood that such descriptions are merely for convenience, and these actions are in fact generated by a computing device, processor, controller, or other means of executing firmware, software, routines, instructions, etc., and performing such operations enables an actuator or other means to interact with the physical world.

[0088] Although specific embodiments of the invention have been described above, it will be understood that the invention can be practiced in ways other than those described. The above description is intended to be illustrative and not restrictive. Therefore, it will be apparent to those skilled in the art that modifications can be made to the described invention without departing from the scope of the claims set forth below.

Claims

1. A measurement device for a photolithography system, comprising: A plurality of independently movable fingers are configured to control the shape of the irradiated area of ​​the pattern forming apparatus, wherein one or more of the independently movable fingers include one or more reflective surfaces. and One or more radiation sensors; The one or more reflective surfaces of the one or more independently movable fingers are configured to reflect radiation toward the one or more radiation sensors.

2. The measuring device according to claim 1, wherein the one or more radiation sensors are intensity sensors.

3. The measuring device according to claim 1 or 2, wherein the one or more radiation sensors are imaging sensors.

4. The measuring device according to any one of the preceding claims, wherein the one or more radiation sensors are arranged in one or more arrays.

5. The measuring apparatus according to any one of the preceding claims, wherein the one or more reflective surfaces comprise one or more angled reflective surfaces configured to reflect radiation in a direction substantially parallel to the pattern forming apparatus.

6. The measuring device according to claim 5, wherein at least one of the one or more reflective surfaces has an angle between 30° and 60° relative to the normal direction of the pattern forming apparatus.

7. The measuring device according to any one of the preceding claims, wherein the one or more reflective surfaces comprise one or more reflective surfaces substantially parallel to the pattern forming apparatus.

8. The measuring device according to any one of the preceding claims, wherein at least one of the one or more reflective surfaces is concave.

9. A photolithography system comprising a measurement device according to claim 1 or any claim 1, wherein the photolithography system further comprises: Radiation source; An irradiation system configured to modulate a radiation beam; and A support structure configured to support a pattern forming apparatus capable of imparting a pattern to the radiation beam in its cross-section to form a patterned radiation beam.

10. A method for controlling a photolithography system, the photolithography system comprising: Radiation source; An irradiation system configured to modulate a radiation beam; and A support structure configured to support a pattern forming apparatus capable of imparting a pattern to the radiation beam in the cross-section of the radiation beam to form a patterned radiation beam; Measurement equipment, the measurement equipment comprising: A plurality of independently movable fingers, the plurality of independently movable fingers being configured to control the shape of an irradiated area of ​​a pattern forming apparatus, wherein one or more of the independently movable fingers include one or more reflective surfaces; and One or more radiation sensors; The one or more reflective surfaces of the one or more independently movable fingers are configured to reflect radiation toward the one or more radiation sensors; The method includes: The characteristics of reflected radiation are measured using the one or more radiation sensors mentioned above; The characteristics of the radiation beam are determined based on the measured characteristics of the reflected radiation; and The state of the lithography system is changed in response to the characteristics of the radiation beam.

11. The method of claim 10, wherein changing the state of the photolithography system comprises: Move one or more of the independently movable fingers.

12. The method according to claim 10 or 11, wherein changing the state of the photolithography system comprises: Change the configuration of one or more optical elements of the irradiation system or the configuration of the radiation source.

13. The method according to any one of claims 10 to 12, wherein the characteristics of the radiation beam are angular intensity distribution and / or spatial intensity distribution.

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