Lithography apparatus and illumination uniformity correction system

Abstract

An illumination adjustment device for adjusting cross-slot illumination of a beam in a lithographic apparatus comprises a plurality of fingers to adjust the cross-slot illumination to conform to a selected intensity distribution. Each finger has a distal edge comprising at least two segments. The two segments form an indentation of the distal edge.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 839,088, filed on April 26, 2019, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to a lithographic apparatus and an illumination uniformity correction system, for example, a system and method for correcting illumination non-uniformity in a lithographic apparatus and system. Background Art

[0004] A lithographic apparatus is a machine that applies a desired pattern to a substrate (usually to a target portion of the substrate). A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In this case, a pattern forming device (optionally referred to as a mask or reticle) can be used to produce a circuit pattern to be formed on a single layer of the IC. The pattern can be transferred to a target portion (e.g., including part of a die, one die, or several dies) on a substrate (e.g., a silicon wafer). The transfer of the pattern is usually via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are patterned continuously. Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing the entire pattern to the target portion at the same time; and so-called scanners, in which each target portion is irradiated by scanning the pattern with a radiation beam in a given direction (the "scanning" direction), while simultaneously scanning the target portion parallel or antiparallel to this scanning direction. It is also possible to transfer the pattern from the pattern forming device to the substrate by imprinting the pattern onto the substrate.

[0005] Another lithography system is an interference lithography system, in which there is no patterning device, but rather the beam is split into two beams and the two beams are caused to interfere at a target portion of the substrate using a reflection system. The interference causes a line to be formed at the target portion of the substrate.

[0006] The lithographic apparatus typically includes an illumination system that conditions the radiation generated by the radiation source before it is incident on the pattern forming device. The illumination system may, for example, modify one or more characteristics of the radiation, such as polarization and / or illumination mode. The illumination system may include a uniformity correction system that corrects or reduces non-uniformities (e.g., intensity non-uniformities) present in the radiation. The uniformity correction device may employ an actuating finger that is inserted into the edge of the radiation beam to correct for intensity variations. The spatial width of the illumination that can be adjusted by the uniformity correction system depends, among other things, on the size of the fingers and the size of the actuating device used to move the fingers in the uniformity correction system. It is not unimportant to modify the finger parameters according to a known working design, because such modifications may result in undesired changes in one or more characteristics of the radiation beam.

[0007] In order to achieve tolerances in image quality on the patterning device and substrate, it is desirable to have an illumination beam with controlled uniformity. It is common to have an illumination beam with a non-uniform intensity distribution before being reflected by or transmitted through the patterning device. It is desirable to control the illumination beam to achieve improved uniformity at various stages in the lithography process. Uniformity can refer to a constant intensity across a relevant cross section of the illumination beam, but can also refer to the ability to control the illumination to achieve selected uniformity parameters. The patterning device imparts a pattern onto the radiation beam, which is then projected onto the substrate. The image quality of this projected beam is affected by the uniformity of the beam.

[0008] Therefore, it is desirable to control illumination uniformity so that the lithography tool performs the lithography process as efficiently as possible to maximize manufacturing throughput and profitability, minimize manufacturing defects, and reduce the cost per tool. Summary of the invention

[0009] In some embodiments, an illumination adjustment device for adjusting cross-slot illumination of a beam in a lithographic apparatus includes a plurality of fingers configured to adjust the cross-slot illumination to conform to a selected intensity distribution. Each finger has a distal edge including at least two segments. The at least two segments form an indentation of the distal edge.

[0010] In some embodiments, a uniformity correction system for adjusting cross-slot illumination of a scanned beam in a lithographic apparatus includes a plurality of fingers configured to adjust the cross-slot illumination to conform to a selected intensity distribution. Each finger has a distal edge including at least two teeth.

[0011] In some embodiments, a lithographic apparatus includes an illumination system, an illumination adjustment device, a support, and a projection system. The illumination adjustment device includes a plurality of fingers. Each finger has a distal edge including at least two segments, and the at least two segments form an indentation of the distal edge. The illumination system is configured to generate a radiation beam, the beam including cross-slot illumination. The plurality of fingers are configured to adjust the cross-slot illumination to conform to a selected intensity distribution. The support is configured to support a pattern forming device, the pattern forming device being configured to impart a pattern to the beam. The projection system is configured to project the patterned beam onto a substrate.

[0012] Other features and beneficial effects of the present invention and the structure and operation of various embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be noted that the present invention is not limited to the specific embodiments described herein. Such embodiments are shown herein for illustrative purposes only. Based on the teachings contained herein, additional embodiments will be apparent to those skilled in the relevant art. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and enable one skilled in the relevant art to make and use the invention.

[0014] Figure 1A A schematic diagram of a reflective lithography apparatus according to some embodiments is shown.

[0015] Figure 1B A schematic diagram of a transmissive lithography apparatus according to some embodiments is shown.

[0016] Figure 2 A more detailed schematic diagram of a reflective lithography apparatus according to some embodiments is shown.

[0017] Figure 3 A schematic diagram of a lithography cell is shown in accordance with some embodiments.

[0018] Figure 4A A schematic diagram showing a portion of a uniformity correction system according to some embodiments is shown.

[0019] Figure 4B A graph showing the intensity of cross-slot illumination according to some embodiments.

[0020] Figure 5 A schematic diagram of a pupil is shown in accordance with some embodiments.

[0021] Figure 6 A schematic diagram illustrating the distal edge of a finger used in an illumination modulation device according to some embodiments.

[0022] Figure 7Bar graphs showing the resulting local intensity fluctuations for different pupil and finger geometries according to some embodiments.

[0023] Features and benefits of the present invention will become more apparent from the following detailed description in conjunction with the accompanying drawings, in which like reference symbols identify corresponding elements throughout the text. In the accompanying drawings, like reference numerals generally indicate identical, functionally similar, and / or structurally similar elements. In addition, generally, the leftmost digit of a reference numeral identifies the drawing in which the reference numeral first appears. Unless otherwise specified, the drawings provided throughout this disclosure should not be construed as drawings drawn to scale. DETAILED DESCRIPTION

[0024] This specification discloses one or more embodiments that include the features of the present invention. The disclosed embodiments are merely illustrative of the present invention. The scope of the present invention is not limited to the disclosed embodiments. The present invention is defined by the appended claims.

[0025] The described embodiments and references in this specification to "one embodiment," "an embodiment," "an example embodiment," etc. indicate that the described embodiments may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. In addition, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, it should be understood that it is within the knowledge of those skilled in the art to implement this feature, structure, or characteristic in conjunction with other embodiments, whether or not explicitly described.

[0026] For ease of description, spatially relative terms such as "below," "beneath," "below," "above," "on," "upper," etc. may be used herein to describe the relationship of one element or feature to another element(s) or feature(s) illustrated in the drawings. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the drawings. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may be interpreted accordingly.

[0027] The term "approximately" as used herein indicates a value of a given quantity that may vary based on a particular technology. Based on a particular technology, the term "approximately" may indicate a value of a given quantity that varies within, for example, 10-30% of the value (e.g., ±10%, ±20%, or ±30% of the value).

[0028] Embodiments of the present disclosure may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present disclosure may also be implemented as instructions stored in a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism 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 a read-only memory (ROM), a random access memory (RAM); a disk storage medium; an optical storage medium; a flash memory device; electrical, optical, acoustic, or other forms of propagation signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. In addition, firmware, software, routines, and / or instructions may be described herein as performing certain actions. However, it should be understood that such descriptions are for simplicity only, and such actions are actually caused by computing devices, processors, controllers, or other devices that execute firmware, software, routines, instructions, etc.

[0029] Before describing such embodiments in further detail, however, it is helpful to present an example environment in which embodiments of the present disclosure may be implemented.

[0030] Example Lithography System

[0031] Figure 1A and 1B Schematic illustrations of lithographic apparatus 100 and lithographic apparatus 100' are shown, respectively, in which embodiments of the present disclosure may be implemented. Each of lithographic apparatus 100 and lithographic apparatus 100' comprises the following: an illumination system (illuminator) IL configured to condition a radiation beam B (e.g., deep ultraviolet or extreme ultraviolet radiation); a support structure (e.g., a mask stage) MT configured to support a pattern forming device (e.g., a mask, a reticle, or a dynamic pattern forming device) MA and connected to a first positioner PM configured to accurately position the pattern forming device MA; and a substrate stage (e.g., a wafer stage) WT configured to hold a substrate (e.g., a resist coated wafer) W and connected to a second positioner PW configured to accurately position the substrate W. The lithographic apparatus 100 and 100' also have a projection system PS configured to project a pattern imparted to the radiation beam B by the pattern forming device MA onto a target portion (e.g., comprising one or more dies) C of the substrate W. In the lithographic apparatus 100, the pattern forming device MA and the projection system PS are reflective. In the lithographic apparatus 100', the patterning device MA and the projection system PS are transmissive.

[0032] The illumination system IL may include various types of optical components, such as refractive, reflective, catadioptric, magnetic, electromagnetic, electrostatic or other types of optical components or any combination thereof, for directing, shaping or controlling the radiation beam B. The illumination system IL may also include an energy sensor ES that provides one or more measurements of, for example, energy per pulse, photon energy, intensity, average power, etc. The illumination system IL may include a measurement sensor MS for measuring the movement of the radiation beam B; and a uniformity compensator UC that allows control of the uniformity of the illumination gap. The measurement sensor MS may also be arranged at other locations. For example, the measurement sensor MS may be located on or near the substrate table WT.

[0033] The support structure MT holds the patterning device MA in a manner that depends on the orientation of the patterning device MA relative to the reference frame, the design of at least one of the lithographic apparatuses 100 and 100', and other conditions (such as whether the patterning device MA is held in a vacuum environment). The support structure MT may use mechanical, vacuum, electromagnetic or other clamping techniques to hold the patterning device MA. The support structure MT may be, for example, a frame or a stage that may be fixed or movable, as desired. By using sensors, the support structure MT may ensure that the patterning device MA is in a desired position, for example relative to the projection system PS.

[0034] The term “patterning device” MA should be broadly interpreted as referring to any device that can be used to impart a radiation beam B with a pattern in its cross-section so as to create a pattern in a target portion C of the substrate W. The pattern imparted to the radiation beam B may correspond to a specific functional layer in the device being created in the target portion C to form an integrated circuit.

[0035] The pattern forming device MA can be a transmissive device (e.g. Figure 1B lithography apparatus 100') or reflective (such as Figure 1A 100). Examples of pattern forming devices MA include reticles, masks, programmable mirror arrays, or programmable LCD panels. Masks are known in lithography and include mask types such as binary, alternating phase shift, or attenuated phase shift, as well as various hybrid mask types. Examples of programmable mirror arrays employ a matrix arrangement of small mirrors, each of which can be individually tilted to reflect an incident radiation beam in different directions. The tilted mirrors impart a pattern into a radiation beam B, which is reflected by the matrix of small mirrors.

[0036] The term "projection system" PS may cover any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and / or electrostatic optical systems or any combination thereof, as appropriate for the exposure radiation used and / or for other factors such as the use of an immersion liquid on the substrate W or the use of a vacuum. A vacuum environment may be used for EUV or electron beam radiation, as other gases may absorb too much radiation or electrons. Therefore, a vacuum environment may be provided to the entire beam path by means of vacuum walls and a vacuum pump.

[0037] The lithographic apparatus 100 and / or lithographic apparatus 100' may be of a type having two (dual stage) or more substrate tables WT (and / or two or more mask tables). In such "multi-stage" machines, additional substrate tables WT may be used in parallel, or preparatory steps may be performed on one or more tables while one or more other substrate tables WT are being used for exposure. In some cases, the additional tables may not be substrate tables WT.

[0038] The lithographic apparatus may also be of a type in which at least part of the substrate may be covered by a liquid having a relatively high refractive index (e.g., water) to fill the space between the projection system and the substrate. Immersion liquid may also be applied to other spaces in the lithographic apparatus, for example, between the mask and the projection system. Immersion techniques are known in the art for increasing the numerical aperture of the projection system. The term "immersion" as used herein does not mean that the structure (such as the substrate) must be immersed in the liquid, but only means that the liquid is located between the projection system and the substrate during exposure.

[0039] refer to Figure 1A and 1B , the illuminator IL receives a radiation beam from a radiation source SO. For example, when the source SO is an excimer laser, the source SO and the lithographic apparatus 100, 100' may be separate physical entities. In this case, the source SO is not considered to form part of the lithographic apparatus 100 or 100', and the radiation beam B is delivered to the lithographic apparatus 100 or 100' by means of a beam delivery system BD (in Figure 1B The radiation is delivered from the source SO to the illuminator IL (including, for example, suitable guide mirrors and / or a beam expander). In other cases, for example, when the source SO is a mercury lamp, the source SO may be an integral part of the lithographic apparatus 100, 100'. The source SO and the illuminator IL (together with the beam delivery system BD, if necessary) may be referred to as a radiation system.

[0040] The illuminator IL may comprise an adjuster AD (at Figure 1BIn general, at least the outer and / or inner radial extent (commonly referred to as "σ-outer" and "σ-inner", respectively) of the intensity distribution in a pupil plane of the illuminator can be adjusted. Furthermore, the illuminator IL may include various other components (in Figure 1B The illuminator IL may be used to condition the radiation beam B to have a desired uniformity and intensity distribution in its cross-section. The desired uniformity of the radiation beam B may be maintained by using a uniformity compensator UC. The uniformity compensator UC includes a plurality of protrusions (e.g., fingers) that may be adjusted in the path of the radiation beam B to control the uniformity of the radiation beam B. A sensor ES may be used to monitor the uniformity of the radiation beam B.

[0041] refer to Figure 1A , a radiation beam B is incident on and patterned by a pattern forming device (e.g., a mask) MA, which is held on a support structure (e.g., a mask table) MT. In the lithographic apparatus 100, the radiation beam B is reflected from the pattern forming device (e.g., a mask) MA. After reflection from the pattern forming device (e.g., a mask) MA, the radiation beam B passes through a projection system PS, which focuses the radiation beam B onto a target portion C of a substrate W. With the aid of a second positioner PW and a position sensor IF2 (e.g., an interferometric device, a linear encoder, or a capacitive sensor), the substrate table WT can be precisely moved (e.g., to position different target portions C in the path of the radiation beam B). Similarly, a first positioner PM and a further position sensor IF1 can be used to precisely position the pattern forming device (e.g., a mask) MA relative to the path of the radiation beam B. The pattern forming device (e.g., mask) MA and the substrate W can be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2.

[0042] refer to Figure 1B , the radiation beam B is incident on and patterned by a pattern forming device (e.g., a mask MA) which is held on a support structure (e.g., a mask table MT). After traversing the mask MA, the radiation beam B passes through a projection system PS which focuses the beam onto a target portion C of the substrate W. The projection system has a pupil conjugate PPU to an illumination system pupil IPU. Part of the radiation is emitted from the intensity distribution at the illumination system pupil IPU and traverses the mask pattern without being affected by diffraction at the mask pattern, and produces an image of the intensity distribution at the illumination system pupil IPU. The desired uniformity of the radiation beam B can be maintained by using a uniformity compensator UC to control the uniformity of the radiation beam B. A sensor ES can be used to monitor the uniformity of the radiation beam B.

[0043] The projection system PS projects an image MP' of the mask pattern MP onto a photoresist layer coated on a substrate W, wherein the image MP' is formed by a diffraction beam generated by radiation from an intensity distribution according to the mask pattern MP. For example, the mask pattern MP may include an array of lines and spaces. The diffraction of radiation at the array and different from the zero-order diffraction generates a diverted diffraction beam with a change in direction in a direction perpendicular to the lines. The non-diffracted beam, the so-called zero-order diffraction beam, crosses the pattern without any change in the propagation direction. The zero-order diffraction beam crosses the upper lens or upper lens group of the projection system PS, upstream of the pupil conjugate PPU of the projection system PS to reach the pupil conjugate PPU. A portion of the intensity distribution in the plane of the pupil conjugate PPU and associated with the zero-order diffraction beam is an image of the intensity distribution in the illumination system pupil IPU of the illumination system IL. The aperture device PD is, for example, arranged at or substantially at a plane including the pupil conjugate PPU of the projection system PS.

[0044] The projection system PS is arranged to capture not only the zero-order diffraction beam, but also the first-order or first-order and higher-order diffraction beams (not shown) by means of a lens or lens group L. In some embodiments, dipole illumination for imaging a line pattern extending in a direction perpendicular to the line can be used to exploit the resolution enhancement effect of dipole illumination. For example, the first-order diffraction beam interferes with the corresponding zero-order diffraction beam at the level of the wafer W to produce an image and process window of the line pattern MP at the highest possible resolution (i.e., the available depth of focus combined with the allowable exposure dose deviation). In some embodiments, astigmatism aberrations can be reduced by providing radiation poles (not shown) in the opposite quadrants of the illumination system pupil IPU. In addition, in some embodiments, astigmatism aberrations can be reduced by blocking the zero-order beam in the pupil conjugate PPU of the projection system associated with the radiation poles in the opposite quadrant. This is described in more detail in U.S. Patent No. US 7,511,799 B2, issued on March 31, 2009, which is incorporated herein by reference in its entirety.

[0045] With the help of a second positioner PW and a position sensor IF (e.g. an interferometric device, a linear encoder or a capacitive sensor), the substrate table WT can be precisely moved (e.g. to position a different target portion C in the path of the radiation beam B). Similarly, the first positioner PM and another position sensor ( Figure 1B ) can be used to accurately position the mask MA relative to the path of the radiation beam B (eg after mechanical retrieval from a mask library or during scanning).

[0046] In general, movement of the mask table MT can be achieved with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning), which form part of the first positioner PM. Similarly, movement of the substrate table WT can be achieved using a long-stroke module and a short-stroke module, which form part of the second positioner PW. In the case of a stepper (as opposed to a scanner), the mask table MT can be connected only to a short-stroke actuator or the mask table MT can be fixed. Mask MA and substrate W can be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. Although the substrate alignment marks (as shown) occupy dedicated target portions, they can be located in the space between target portions (called scribe alignment marks). Similarly, in the case where more than one die is provided on the mask MA, the mask alignment marks can be located between the dies.

[0047] The mask table MT and the pattern forming device MA may be in the vacuum chamber V, where the pattern forming device (such as a mask) may be moved into and out of the vacuum chamber V using an in-vacuum robot IVR. Alternatively, when the mask table MT and the pattern forming device MA are outside the vacuum chamber, an out-of-vacuum robot may be used for various transport operations similar to the in-vacuum robot IVR. Both the in-vacuum robot and the out-of-vacuum robot need to be calibrated for smoothly transferring any payload (e.g., a mask) to a transfer station with a fixed kniematic mount.

[0048] The lithographic apparatuses 100 and 100' may be used in at least one of the following modes:

[0049] 1. In step mode, the support structure (e.g. mask table) MT and substrate table WT remain essentially stationary and the entire pattern imparted to the radiation beam B is projected simultaneously onto a target portion C (i.e. a single static exposure). The substrate table WT is then shifted in the X and / or Y direction so that a different target portion C can be exposed.

[0050] 2. In scan mode, the support structure (e.g. mask table) MT and substrate table WT are scanned synchronously and a pattern imparted to the radiation beam B is projected onto a target portion C (i.e. a single dynamic exposure). The velocity and direction of the substrate table WT relative to the support structure (e.g. mask table) MT may be determined by the (de-)magnification and image reversal characteristics of the projection system PS.

[0051] 3. In another mode, the support structure (e.g. mask table) MT remains substantially stationary, holding the programmable patterning device, and the substrate table WT is moved or scanned while a pattern imparted to the radiation beam B is projected onto a target portion C. A pulsed radiation source SO may be employed, and the programmable patterning device updated as required after each movement of the substrate table WT or between successive radiation pulses during a scan. This mode of operation may be readily adapted to maskless lithography which utilizes a programmable patterning device, such as a programmable mirror array.

[0052] Combinations and / or variations of the described modes of use or entirely different modes of use may also be employed.

[0053] In another embodiment, the lithographic apparatus 100 includes an extreme ultraviolet (EUV) source configured to generate an EUV radiation beam for EUV lithography. Generally, the EUV source is configured in a radiation system, and a corresponding illumination system is configured to condition the EUV radiation beam of the EUV source.

[0054] Figure 2 The lithographic apparatus 100 is shown in more detail, and the lithographic apparatus includes a source collector device SO, an illumination system IL and a projection system PS. The source collector device SO is constructed and arranged so that a vacuum environment can be maintained in a closed structure 220 of the source collector device SO. The EUV radiation emitting plasma 210 can be formed by a discharge plasma source. EUV radiation can be generated by a gas or vapor (such as xenon, lithium vapor or tin vapor), in which a very hot plasma 210 is generated to emit radiation in the EUV range of the electromagnetic spectrum. For example, the extremely hot plasma 210 is generated by a discharge that causes at least partially ionized plasma. For the effective generation of radiation, a partial pressure of xenon, lithium, tin vapor or any other suitable gas or vapor, such as 10 Pascals (Pa), may be required. In some embodiments, an excited tin (Sn) plasma is provided to generate EUV radiation.

[0055] The radiation emitted by the hot plasma 210 is transferred from the source chamber 211 to the collector chamber 212 via an optional gas barrier or contaminant trap 230 (also referred to as a contaminant barrier or foil trap in some cases) positioned in or behind an opening in the source chamber 211. The contaminant collector 230 may include a channel structure. The contaminant collector 230 may also include a gas barrier or a combination of a gas barrier and a channel structure. The contaminant collector or contaminant barrier 230 further indicated herein includes at least a channel structure.

[0056] The collector cavity 212 may include a radiation collector CO, which may be a so-called grazing incidence collector. The radiation collector CO has an upstream radiation collector side 251 and a downstream radiation collector side 252. Radiation traversing the collector CO may be reflected by a grating spectral filter 240 to be focused in a virtual source point IF. The virtual source point IF is often referred to as an intermediate focus, and the source collector arrangement is arranged such that the intermediate focus IF is located at or near an opening 219 in the enclosed structure 220. The virtual source point IF is an image of the radiation emitting plasma 210. The grating spectral filter 240 is particularly useful for suppressing infrared (IR) radiation.

[0057] The radiation then traverses an illumination system IL which may include a faceted field mirror device 222 and a faceted pupil mirror device 224 which are arranged to provide a desired angular distribution of the radiation beam 221 at the patterning device MA and a desired uniformity of radiation intensity at the patterning device MA. When the radiation beam 221 is reflected at the patterning device MA held by the support structure MT, a patterned beam 226 is formed and the patterned beam 226 is imaged by the projection system PS via reflective elements 228, 229 onto a substrate W held by a wafer stage or substrate table WT.

[0058] There may typically be more elements than those shown in the illumination optics unit IL and the projection system PS. Depending on the type of lithographic apparatus, a grating spectral filter 240 may optionally be present. In addition, there may be more than Figure 2 The reflectors shown in FIG. 5 are more numerous than those in FIG. Figure 2 One to six additional reflective elements may also be present in the projection system PS shown in FIG.

[0059] In some embodiments, the illumination optics unit IL may comprise a sensor ES which provides a measurement of one or more of, for example, energy per pulse, photon energy, intensity, average power, etc. The illumination optics unit IL may comprise a measurement sensor MS for measuring the movement of the radiation beam B, and a uniformity compensator UC which allows control of the uniformity of the illumination gap. The measurement sensor MS may also be arranged at other locations. For example, the measurement sensor MS may be on or near the substrate table WT.

[0060] like Figure 2, the collector optics CO is depicted as a nested collector with grazing incidence reflectors 253, 254 and 255, which is only an example of a collector (or collector mirror). The grazing incidence reflectors 253, 254 and 255 are arranged axially symmetrically around the optical axis O, and this type of collector optics CO is preferably used in conjunction with a discharge plasma source (commonly referred to as a DPP source).

[0061] Exemplary Lithographic Cell

[0062] Figure 3 A lithography unit 300 according to some embodiments is shown, sometimes also referred to as a lithography unit or cluster. The lithography apparatus 100 or 100' may form a part of the lithography unit 300. The lithography unit 300 may also include one or more devices to perform pre-exposure processes and post-exposure processes on a substrate. Conventionally, these include: a spin coater SC for depositing a resist layer, a developer DE for developing the exposed resist, a chill plate CH, and a baking plate BK. The substrate handler or robot RO picks up substrates from input / output ports I / O1, I / O2, moves these substrates between different process devices, and delivers them to the feed station LB of the lithography apparatus 100 or 100'. These devices (generally referred to as tracks) are under the control of a track control unit TCU, which itself is controlled by a monitoring system SCS, which also controls the lithography apparatus via a lithography control unit LACU. Therefore, different devices can be operated to maximize production volume and processing efficiency.

[0063] Exemplary Uniformity Correction System

[0064] Figure 4A A uniformity correction system 400 (eg, Figure 1A , Figure 1B and Figure 2 In some embodiments, the uniformity correction system 400 includes one or more sensors 402 (e.g., sensors ES, Figure 1A , 1B and 2) and a plurality of uniformity compensator elements 404 (eg, fingers). Each of the uniformity compensator elements 404 includes a distal edge 406.

[0065] exist Figure 4A4. A cross slot illumination 408 (e.g., a cross section of an illumination beam or an illumination slit) is shown in FIG. The cross slot illumination 408 is represented as a 2D intensity map having different intensity regions 410, 412, and 414. For example, intensity region 410 has a low relative intensity and is positioned on an outer portion of the cross slot illumination 408. In contrast, intensity region 414 has a high relative intensity and is positioned toward a center portion of the cross slot illumination 408. In some embodiments, the cross slot illumination 408 is generated by using a pupil system (not shown) upstream of the uniformity correction system 400 and scanning the beam.

[0066] In some embodiments, the shape of the cross-slot illumination 408 has a substantially arcuate geometry. Each distal edge 406 includes a straight distal edge oriented to approximately follow the curvature of the arcuate geometry. In some embodiments, the shape of the cross-slot illumination 408 has a substantially rectangular geometry (not shown), and each distal edge includes a straight edge oriented to approximately follow the shape of the rectangular geometry. Each uniformity compensator element 404 is attached to a corresponding actuator.

[0067] In some embodiments, the spacing (eg, pitch or finger pitch) between the centers of each uniformity compensator element 404 is between approximately 1 mm-7 mm along the X-direction. Figure 4A The reference XY coordinate system provided in is for ease of discussion and is not limiting. In some embodiments, the pitch of uniformity compensator elements 404 along the X direction is approximately 4 mm.

[0068] Various shaping techniques may be used to fabricate the uniformity compensator element 404. For example, in some embodiments, the uniformity compensator element 404 may be fabricated using electrical discharge machining (EDM).

[0069] In some embodiments, the uniformity correction system 400 can modify or adjust an illumination beam used in a lithography operation. For example, each uniformity compensator element 404 can be adjusted using a corresponding actuator in the path of the illumination beam (e.g., at least overlapping the cross-slot illumination 408) so that the intensity distribution of the cross-slot illumination 408 conforms to a selected intensity distribution. Example operations of uniformity compensators can be found in commonly owned U.S. Patent No. 8,629,973 B2 (filed May 28, 2010) and U.S. Patent No. 9,134,620 B2 (filed April 12, 2012), which are incorporated herein by reference in their entirety.

[0070] Figure 4BA graph 416 of the intensity of the cross-slot illumination 408 is shown according to some embodiments. The vertical axis of the graph 416 represents the scan-integrated intensity I(x) of the cross-slot illumination 408. With respect to the scan integration, the intensity of the cross-slot illumination 408 can be described in terms of an XY coordinate system, e.g., I(x, y). This 2D representation can be simplified to a 1D representation, i.e., I(x) (e.g., line power, irradiance, or intensity), by integrating along the so-called scan direction. If the intensity fluctuations along the X direction are of interest, the scan integration is performed in the Y direction, as shown in the following equation:

[0071]

[0072] The horizontal axis of the graph 416 represents the position corresponding to a given X-coordinate of the cross-slot illumination 408. The vertical line 418 is provided to illustrate the correlation between the cross-slot illumination 408 and the given X-coordinate. The plot line 420 represents an example scan-integrated intensity distribution in the absence of the uniformity correction system 400 (e.g., removing the uniformity compensator element 404 from the path of the illumination beam). In the plot line 420, at least two types of non-uniformities (e.g., non-flat lines) are discernible: (1) a general trend similar to an overall peak and (2) local intensity fluctuations (e.g., small fluctuations with a spatial frequency between about 3 mm-5 mm). The local intensity fluctuations may also be referred to herein as short-range or high-frequency (spatial) fluctuations. In order to ensure image quality when performing a lithography process using the cross-slot illumination 408, it is important to reduce both types of non-uniformities.

[0073] In some embodiments, the overall peak non-uniformity is addressed by using a uniformity correction system 400 for the cross-slot illumination 408. For example, inserting and adjusting a uniformity compensator element 404 in the path of the illumination beam can produce a scan-integrated intensity distribution represented by plot line 422. And, the scan-integrated intensity distribution represented by plot line 424 is desired for the lithography process. Plot line 424 exhibits a reduction or prevention of local intensity fluctuations (e.g., making the intensity more uniform). Plot line 422 can be produced by using a distal edge 406 having a straight distal edge 426 and / or a chamfered (or beveled) edge 428, the straight distal edge 426 being oriented to approximately follow the geometry of the cross-slot illumination 408. Here, the dashed line structure represents an alternative version of the distal edge 426 represented as a single solid line.

[0074] The local intensity fluctuations visible in plot lines 420 and 422 may be exacerbated by, for example, the spacing between the centers of the fingers (i.e., the pitch), the pupil configuration, the intensity gradient, and the finger shape. Finger spacing and pupil configuration are related. Pupil configuration refers to the arrangement of the illumination openings upstream of the uniformity correction system and is not to be confused with cross-slot illumination 408.

[0075] The pupil may have one or more openings of a particular size, shape, and arrangement. Figure 5 Pupils 500, 504, and 508 are shown according to some embodiments. For ease of discussion, Figure 5 The XY coordinate system shown in Figure 4A and Figure 6 The coordinate system of the image processing apparatus 500 is consistent with that of the image processing apparatus 501, and therefore may or may not be consistent with other figures or descriptions. In some embodiments, the pupil 500 includes two openings 502 spaced apart by a distance d1 along the X direction. The shape of the opening 502 is an ellipse or a quasi-ellipse. The major axes of the openings 502 are roughly aligned along the Y direction. In some embodiments, the pupil 504 includes two openings 506 spaced apart by a distance d2 along the Y direction. The shape of the opening 506 is an ellipse or a quasi-ellipse. The major axes of the openings 506 are roughly aligned along the X direction. Due to the double opening arrangement, the pupil 500 and the pupil 504 can be described by the term "dipole" (e.g., a dipole pupil). In some embodiments, the pupil 508 includes four openings 510. The openings 510 are arranged in a rectangular arrangement. The openings 510 are arranged so that the two openings are spaced apart by a distance d3 along the X direction, and the two openings are spaced apart by a distance d4 along the Y direction. The shape of the opening 506 has at least three-fold symmetry or higher symmetry (e.g., a circle has an infinite axis of symmetry). Because of the four-opening arrangement, pupil 508 can be described by the term "quadrupole" (e.g., quadrupole pupil). Other pupil configurations (e.g., opening shapes, number of openings, sizes, spatial arrangements, etc.) are also possible, and are too numerous to list individually. With appropriate pupil configuration, the critical dimensions of lithographic structures can be reduced.

[0076] As mentioned previously, finger spacing and pupil configuration are related. Figure 4A , when the pitch of the uniformity compensator elements 404 is along the pitch used to generate the illumination beam (e.g., Figure 5Problems arise when the direction of the pupil 500 in the image is matched to the spacing of the pupil opening. If the uniformity compensator element 404 and the spacing are substantially similar to d1, light leakage between the fingers will exacerbate local intensity fluctuations, and the resulting intensity distribution will be similar to the intensity distribution of plot lines 420 and 422. It would be reasonable for a technician to try to solve the problem by changing the finger spacing so that it is substantially different from d1. However, it is not easy to modify the finger parameters based on a known working design. For example, software modeling can show that changing the finger spacing will produce inconsistent results - in some cases amplifying local intensity fluctuations rather than promoting uniformity. Software modeling can be performed using, for example, ray modeling and / or MATLAB, among others.

[0077] In addition to modifying the finger spacing, there are other ways to improve uniformity more consistently. For example, it can be shown that modifying the shape of the distal edges of the fingers can improve uniformity across a variety of pupil configurations.

[0078] Figure 6 The distal edge 602 of a finger used in an illumination adjustment device 600 (e.g., a uniformity correction system) is shown according to some embodiments. In some embodiments, the distal edge 602 includes at least two segments (e.g., facets) joined at a vertex. In some embodiments, the distal edge 602 may include at least four, eight, or ten segments. In some embodiments, the distal edge 602 includes at least two, three, four, five, six, seven, eight, or nine vertices.

[0079] In some embodiments, distal edge 602 includes segments 604, 606, 608, 610, and 612. Distal edge 602 also includes segments 614, 616, 618, 620, and 622 corresponding to segments 604, 606, 608, 610, and 612. The correspondence is mirror symmetric about symmetry line 624. Symmetry line 624 passes through the center of distal edge 602. Distal edge 602 also includes vertices 626, 628, 630, and 632. Figure 6 As shown in FIG. 6 , segments 604, 606, 608, 610, and 612 join at vertices 626, 628, 630, and 632. Distal edge 602 also includes vertices 636, 638, 640, and 642. Vertices 636, 638, 640, and 642 have mirror images of vertices 626, 628, 630, and 632 about vertex 634 and line of symmetry 624. Figure 6 As shown in FIG. 6 , segments 614 , 616 , 618 , 620 , and 622 join at vertices 636 , 638 , 640 , and 642 . A group of segments 604 , 606 , 608 , 610 , and 612 joins a group of segments 614 , 616 , 618 , 620 , and 622 at vertex 634 .

[0080] In some embodiments, segments 604, 606, 608, 610, 612, 614, 616, 618, 620, and 622 may be individually curved or straight. Vertices 626, 628, 630, 632, 634, 636, 638, 640, and 642 may be individually pointed or curved.

[0081] In some embodiments, the illumination adjustment device 600 is configured to adjust the cross-slot illumination 646 of the beam in the lithographic apparatus. In order to adjust or correct the uniformity of the cross-slot illumination 646, a portion of the distal edge 602 can protrude outward (e.g., teeth) or be recessed inward. Software modeling shows that the geometric shape of at least one indentation or at least two teeth can improve the uniformity of the cross-slot illumination. Therefore, in some embodiments, at least two segments of the distal edge 602 are joined at the vertex to form an indentation of the distal edge 602 (e.g., segments 606 and 608 are joined at the vertex 628, or segments 610 and 612 are joined at the vertex 632). In some embodiments, the distal edge 602 includes at least four segments, and the at least four segments form at least two indentations of the distal edge 602. In some embodiments, the distal edge 602 includes at least six segments, and the at least six segments form at least three indentations of the distal edge 602. In some embodiments, distal edge 602 includes at least eight segments that form at least four indentations of distal edge 602. For simplicity, we may refer to vertices 628, 632, 638, and 642 as indentations, and vertices 626, 630, 634, 636, and 640 as teeth. In some embodiments, distal edge 602 includes at least three, four, or five teeth.

[0082] In some embodiments, the width of the distal edge 602 is between about 2 mm and 12 mm. In some embodiments, the width of the distal edge 602 is about 7 mm. Here, the term "width" is used to characterize the width of the distal edge 602 according to Figure 6 The span in the X direction of the coordinate system shown in .

[0083] A plurality of fingers for the illumination adjustment device 600 can be constructed by iterating the fingers, each finger having a distal edge 602. In some embodiments, the finger spacing of the illumination adjustment device 600 is between about 1 mm and 7 mm. In some embodiments, the finger spacing of the illumination adjustment device 600 is about 4 mm.

[0084] The general orientation of the distal edge 602 of each finger iteration can be such that the distal edge 602 is substantially aligned with the geometry of the cross-slot illumination 646. Previously with reference to FIG. 4, the distal edge 426 is shown aligned with the local edge of the cross-slot illumination 408 ( Figure 4A ). Similarly, the cross slot illumination 646 can have a substantially arcuate geometry. In some embodiments, the cross slot illumination 646 can have a substantially rectangular geometry. Thus, Figure 6 The orientation of the symmetry line 624 shown in FIG. 4 (along Y) should not be construed as limiting. In some embodiments, the symmetry line 624 is oriented perpendicular to the local edge of the cross-slot illumination. For example, if the distal edge 602 is tilted similar to the distal edge 426 in FIG. 4, the symmetry line 624 may also be tilted. In some embodiments, the distal edge 602 may be substantially asymmetric.

[0085] Various forming techniques can be used to manufacture the distal edge 602. For example, in some embodiments, the distal edge 602 can be manufactured using electrical discharge machining (EDM).

[0086] To solve for finger geometry (eg, distal edge 602) that may improve cross-slot illumination uniformity, in some embodiments, ray modeling and / or MATLAB may be used in conjunction with a global optimization algorithm (eg, Monte Carlo) and solver.

[0087] Figure 7 A bar graph 700 of the resulting local intensity fluctuations for different pupil and finger geometries is shown in accordance with some embodiments. The data in bar graph 700 was generated using software modeling as described above for different arrangements of pupil and finger geometries. The bins on the horizontal axis of bar graph 700 represent different pupils. For example, bin 708 (also referred to as "bipolar X") corresponds to a pupil with bipolar openings distributed along the X direction (e.g., Figure 5 Interval 710 (also referred to as "dipole Y") corresponds to a pupil having dipole openings distributed along the Y direction (e.g., Figure 5 504 in FIG. 5 ). And interval 712 corresponds to a pupil (eg, pupil 508) having quadrupole openings distributed in a square pattern.

[0088] The vertical axis of the bar graph 700 represents the maximum local intensity fluctuation expressed as a percentage value. To clarify the units of the vertical axis of the bar graph 700, we refer to Figure 4B420 and line 430. An important parameter of the local intensity fluctuation is the maximum difference (shown by line 430). In some embodiments, the maximum difference of the plot line 422 shown by line 430 can be expressed as a percentage value. For example, the intensity difference represented by the interval of line 430 can be divided by the nominal (e.g., average) intensity of the plot line 422 and multiplied by 100 to arrive at the percentage units shown in the bar graph 700. It can be seen that the nominal intensity is at about 1.94 (arbitrary units) as indicated by the plot line 424. The nominal intensity can be the average of the plot lines 422 or 424, or the global minimum of the plot line 420. Those skilled in the art will understand that there are many methods for determining the local intensity fluctuation based on percentage. For example, a smoothing algorithm (e.g., a moving average) can be applied to the plot line 422 to arrive at the plot line 424. Then, by comparing the values ​​of the plot lines 422 and 424, the local intensity fluctuation can be determined as a function of the X coordinate. Next, the maximum local intensity fluctuation can be extracted from the resulting LIF(x).

[0089] In bar graph 700, bars 702n, 704n, and 706n (white bars) represent bars that have distal edges (e.g. Figure 4A The maximum local intensity fluctuations caused by the illumination modulating device with fingers having non-recessed geometry at the distal edge 426 in FIG. 702i, 704i and 706i (hatched bars) represent the maximum local intensity fluctuations caused by the use of an illumination modulating device with fingers having a distal edge (particularly as Figure 6 The maximum local intensity fluctuation caused by the illumination adjustment device with fingers with concave geometry at the distal edge 602) shown in FIG.

[0090] At interval 708 including bars 702n and 702i, it is seen that the maximum local intensity fluctuation is reduced from about 0.30% to about 0.24% by using a distal edge with a recess (or toothed) - a reduction of about 20% relative to a non-recessed (or non-toothed) distal edge. The use of a recessed distal edge geometry also reduces the maximum local intensity fluctuation when using a dipole Y (shown by bars 704n and 704i) or a quadrupole pupil (shown by bars 706n and 706i). Thus, embodiments of the present disclosure provide structures and methods for improving uniformity of cross-slot illumination of a beam in a lithographic apparatus.

[0091] In some embodiments using fingers with recessed distal edges, local intensity fluctuations of cross-slot illumination are reduced by at least 5%, 10%, or 20% relative to local intensity fluctuations that would result if non-recessed distal edges were used. In some embodiments using fingers with recessed distal edges, local intensity fluctuations of cross-slot illumination are reduced by at least 0.02%, 0.04%, or 0.06% relative to the nominal intensity of cross-slot illumination.

[0092] The embodiments may be further described using the following terms:

[0093] 1. An illumination adjustment device for adjusting cross-slot illumination of a beam in a lithography device, comprising:

[0094] a plurality of fingers configured to adjust the cross-slot illumination to conform to a selected intensity distribution,

[0095] wherein each finger has a distal edge comprising at least two segments, and

[0096] Wherein said at least two segments form an indentation of said distal edge.

[0097] 2. An illumination modulation device according to clause 1, wherein the at least two segments are straight and / or curved.

[0098] 3. An illumination adjustment device according to item 1, wherein at least a portion of the distal edge is symmetric about a line of symmetry, and the line of symmetry passes through a center position of the distal edge.

[0099] 4. An illumination modulation device according to clause 1, wherein the distal edge comprises at least four segments, wherein the at least four segments form at least two indentations of the distal edge.

[0100] 5. The illumination modulation device according to clause 1, wherein the distal edge comprises at least eight segments, wherein the at least eight segments form at least four indentations of the distal edge.

[0101] 6. An illumination modulation device according to clause 1, wherein the cross-slot illumination comprises a substantially rectangular geometry.

[0102] 7. An illumination modulation device according to item 1, wherein the cross-slot illumination comprises a substantially arcuate geometry.

[0103] 8. The illumination adjustment device of clause 1, wherein the plurality of fingers are mounted on a corresponding plurality of actuators, the plurality of actuators being configured to independently move each of the plurality of fingers to adjust the cross-slot illumination.

[0104] 9. A uniformity correction system for adjusting cross-slot illumination of a scanning beam in a lithography apparatus, comprising:

[0105] a plurality of fingers configured to adjust the cross-slot illumination to conform to a selected intensity distribution,

[0106] Each of the fingers has a distal edge including at least two teeth.

[0107] 10. The uniformity correction system of clause 9, wherein the at least two teeth comprise straight and / or curved segments of the distal edge.

[0108] 11. The uniformity correction system of clause 9, wherein at least a portion of the distal edge is symmetric about a line of symmetry that passes through a center position of the distal edge.

[0109] 12. The uniformity correction system of clause 9, wherein the distal edge comprises at least four teeth.

[0110] 13. The uniformity correction system of clause 9, wherein the at least two teeth engage at an apex such that the apex forms an indentation of the distal edge.

[0111] 14. The uniformity correction system of clause 9, wherein the cross-slot illumination comprises a substantially rectangular geometry.

[0112] 15. The uniformity correction system of clause 9, wherein the cross-slot illumination comprises a substantially arcuate geometry.

[0113] 16. The uniformity correction system of clause 9, wherein the plurality of fingers are mounted on a corresponding plurality of actuators, the plurality of actuators being configured to independently move each of the plurality of fingers to adjust the cross-slot illumination.

[0114] 17. A lithographic apparatus comprising:

[0115] an illumination system configured to generate a radiation beam, the beam comprising cross-slot illumination;

[0116] An irradiation adjustment device, comprising:

[0117] a plurality of fingers configured to adjust the cross-slot illumination to conform to a selected intensity distribution,

[0118] wherein each finger has a distal edge comprising at least two segments, and

[0119] wherein said at least two segments form an indentation of said distal edge,

[0120] a support configured to support a patterning device configured to impart a pattern to the beam; and

[0121] A projection system is configured to project the patterned beam onto a substrate.

[0122] 18. The lithographic apparatus of clause 17, wherein the distal edge comprises at least four segments, wherein the at least four segments form at least two indentations of the distal edge.

[0123] 19. The lithographic apparatus of clause 17, wherein the distal edge comprises at least eight segments, wherein the at least eight segments form at least four indentations of the distal edge.

[0124] 20. The lithographic apparatus of clause 17, wherein:

[0125] The local intensity fluctuation of the cross-slot illumination is based on light leakage between the plurality of fingers; and

[0126] The local intensity fluctuations are reduced by approximately at least 0.02% relative to the nominal intensity of the cross-slot illumination.

[0127] Although specific reference may be made herein to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, LCDs, thin film heads, etc. The skilled person will appreciate that in the case of such alternative applications, any use of the terms "wafer" or "die" herein may be considered synonymous with the more general terms "substrate" or "target portion", respectively. The substrates referred to herein may be processed before or after exposure in, for example, a track unit (a tool that typically applies a resist layer to a substrate and develops the exposed resist), a metrology unit, and / or an inspection unit. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. In addition, the substrate may also be processed more than once, for example to create a multi-layer IC, so the term substrate used herein may also be referred to as a substrate that has included multiple processing layers.

[0128] Although the above may have made specific reference to the use of embodiments of the invention in the context of optical lithography, it will be appreciated that the invention may be used in other applications, such as imprint lithography, and is not limited to optical lithography where circumstances permit. In imprint lithography, the topography in the patterning device defines the pattern created on the substrate. The topography of the patterning device may be pressed into a layer of resist supplied to a substrate, on which the resist is cured by applying electromagnetic radiation, heat, pressure, or a combination thereof. The patterning device is moved out of the resist, leaving a pattern therein after the resist is cured.

[0129] It should be understood that the phrases or terms herein are for the purpose of description and not limitation, so that the terms or phrases of the present disclosure are interpreted by those skilled in the relevant art based on the teachings herein.

[0130] The terms "irradiation adjustment device", "radiation correction system" and the like may be used herein to describe a device that adjusts one or more characteristics of a radiation beam. For example, a uniformity correction system may be referred to as an illumination adjustment device.

[0131] As used herein, the terms "radiation", "beam", "light", "irradiation" and the like may encompass all types of electromagnetic radiation, such as ultraviolet (UV) radiation (e.g., having a wavelength λ of 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm), extreme ultraviolet (EUV or soft X-ray) radiation (e.g., having a wavelength in the range of 5 nm-20 nm, such as 13.5 nm) or hard X-rays operating at less than 5 nm, and particle beams, such as ion beams or electron beams. In general, radiation having a wavelength between about 400 nm and about 700 nm is considered visible radiation; radiation having a wavelength between about 780 nm-3000 nm (or greater) is considered IR radiation. UV refers to radiation having a wavelength of approximately 100 nm-400 nm. In lithography, the term "UV" also applies to wavelengths that can be produced by mercury discharge lamps: G-line 436 nm; H-line 405 nm and / or I-line 365 nm. Vacuum UV or VUV (i.e., UV absorbed by gases) refers to radiation having a wavelength of approximately 100 nm-200 nm. Deep UV (DUV) generally refers to radiation having a wavelength between 126 nm and 428 nm; and in some embodiments, an excimer laser may produce DUV radiation for use within a lithographic apparatus. It will be appreciated that radiation having a wavelength in the range of, for example, 5 nm-20 nm relates to radiation having a particular wavelength band, at least in part, within the range of 5 nm-20 nm.

[0132] The term "substrate" as used herein describes a material on which a layer of material is added. In some embodiments, the substrate itself may be patterned, and the material added on top of it may also be patterned, or may remain unpatterned.

[0133] Although specific reference may be made herein to the use of the apparatus and / or system according to the present invention in IC manufacturing, it should be clearly understood that such an apparatus and / or system has many other possible applications. For example, it can be used to manufacture integrated optical systems, guidance and detection patterns for magnetic domain memories, LCD panels, thin film magnetic heads, etc. It will be understood by those skilled in the art that in the case of such alternative applications, any use of the terms "reticle", "wafer" or "die" herein should be considered to be replaced by the more general terms "mask", "substrate" and "target portion", respectively.

[0134] While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. The description is not intended to limit the invention.

[0135] It should be understood that the detailed description section, rather than the summary and abstract sections, is intended to be used to interpret the claims. The summary and abstract sections may set forth one or more but not all of the exemplary embodiments of the present invention as contemplated by the inventors, and therefore are not intended to limit the present invention and the appended claims in any way.

[0136] The present invention has been described above with the aid of functional building blocks that illustrate implementations of specific functions and their relationships. For ease of description, the boundaries of these functional building blocks have been arbitrarily defined herein. Alternative boundaries may be defined as long as the specific functions and their relationships are appropriately performed.

[0137] The foregoing description of the specific embodiments will reveal the general nature of the invention so fully that others can easily modify and / or adapt these specific embodiments by applying knowledge in the art and without undue experimentation without departing from the general concept of the invention. Therefore, based on the teachings and guidance presented herein, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments.

[0138] The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

1. An illumination adjustment device for adjusting cross-slot illumination of a beam in a lithography device, comprising: a plurality of fingers configured to adjust the cross-slot illumination to conform to a selected intensity distribution, wherein each finger has a distal edge comprising a plurality of segments, and wherein the plurality of segments form a plurality of indentations of the distal edge such that a portion of the plurality of indentations resides near the middle of the cross-slot illumination, on either side of the plurality of indentations, and Wherein at least a portion of the distal edge is aligned with a portion of a shape illuminated by the cross-slot at a corresponding finger.

2. The illumination adjustment device according to claim 1, wherein the plurality of segments are straight and / or curved.

3. The illumination adjustment device according to claim 1, wherein at least a portion of the distal edge is symmetric about a symmetry line, and the symmetry line passes through a center position of the distal edge.

4. The illumination adjustment device according to claim 1, wherein the distal edge includes at least four segments, wherein the at least four segments form at least two indentations of the distal edge.

5. The illumination adjustment device of claim 1, wherein the distal edge comprises at least eight segments, wherein the at least eight segments form at least four indentations of the distal edge.

6. The illumination modulation device of claim 1, wherein the cross-slot illumination comprises a substantially rectangular geometry.

7. The illumination modulation device of claim 1, wherein the cross-slot illumination comprises a substantially arcuate geometry.

8. The illumination adjustment device of claim 1, wherein the plurality of fingers are mounted on a corresponding plurality of actuators, the plurality of actuators being configured to independently move each of the plurality of fingers to adjust the cross-slot illumination.

9. A uniformity correction system for adjusting cross-slot illumination of a scanning beam in a lithography apparatus, comprising: a plurality of fingers configured to adjust the cross-slot illumination to conform to a selected intensity distribution, Each finger has a distal edge comprising at least two teeth and at least a portion of the distal edge is aligned with a portion of a shape illuminated by the cross-slot at the corresponding finger.

10. The uniformity correction system of claim 9, wherein the at least two teeth comprise straight and / or curved segments of the distal edge.

11. The uniformity correction system of claim 9, wherein at least a portion of the distal edge is symmetric about a line of symmetry that passes through a center position of the distal edge.

12. The uniformity correction system of claim 9, wherein the distal edge includes at least four teeth.

13. The uniformity correction system of claim 9, wherein the at least two teeth meet at an apex such that the apex forms an indentation of the distal edge.

14. The uniformity correction system of claim 9, wherein the cross-slot illumination comprises a substantially rectangular geometry.

15. The uniformity correction system of claim 9, wherein the cross-slot illumination comprises a substantially arcuate geometry.

16. The uniformity correction system of claim 9, wherein the plurality of fingers are mounted on a corresponding plurality of actuators configured to independently move each of the plurality of fingers to adjust the cross-slot illumination.

17. A lithographic apparatus comprising: an illumination system configured to generate a radiation beam, the beam comprising cross-slot illumination; An irradiation adjustment device, comprising: a plurality of fingers configured to adjust the cross-slot illumination to conform to a selected intensity distribution, wherein each finger has a distal edge comprising a plurality of segments, and wherein the plurality of segments form a plurality of indentations of the distal edge such that a portion of the plurality of indentations resides near the middle of the cross-slot illumination, on either side of the plurality of indentations, and wherein at least a portion of said distal edge is aligned with a portion of a shape illuminated by said cross-slot at a corresponding finger, a support configured to support a patterning device configured to impart a pattern to the beam; as well as A projection system is configured to project the patterned beam onto a substrate.

18. The lithographic apparatus according to claim 17, wherein: The local intensity fluctuation of the cross-slot illumination is based on light leakage between the plurality of fingers; and The local intensity fluctuations are reduced by approximately at least 0.02% relative to the nominal intensity of the cross-slot illumination.

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