Lithographic apparatus and illumination uniformity correction system

Abstract

To control illumination uniformity so that lithographic tools perform lithography processes as efficiently as possible for maximizing manufacturing capacity and yield rates, minimizing manufacturing defects, and reducing cost per device.SOLUTION: An illumination adjustment apparatus to adjust a cross slot illumination of a beam in a lithographic apparatus includes a plurality of fingers to adjust the cross slot illumination to conform to a selected intensity profile. Each finger has a distal edge that includes at least two segments. The two segments form an indentation of the distal edge.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001]

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 839,088, filed April 26, 2019, which is incorporated herein by reference in its entirety. [Background technology]

[0002]

[0002] The present disclosure relates to lithographic apparatus and illumination uniformity correction systems, for example systems and methods for correcting illumination non-uniformity in lithographic apparatus and systems.

[0003]

[0003] A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. Lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In such cases, a patterning device, alternatively called a mask or reticle, can be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g. comprising part of one or several dies) on the substrate (e.g. a silicon wafer). The transfer of the pattern is typically by 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 which are successively patterned. Conventional lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing the entire pattern onto the target portion in one go, and so-called scanners, in which each target portion is irradiated by scanning the pattern with a radiation beam in a given direction (the "scan" direction) while synchronously scanning the substrate parallel or anti-parallel to the given direction (the "scan" direction). It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.

[0004]

[0004] Another lithography system is an interference lithography system in which there is no patterning device, but rather a light beam is split into two beams and the two beams are made to interfere at a target portion of a substrate through the use of a reflection system. The interference causes a line to be formed in the target portion of the substrate.

[0005]

[0005] A lithographic apparatus typically includes an illumination system that conditions the radiation generated by the radiation source before it is incident on the patterning device. The illumination system may modify one or more characteristics of the radiation, such as, for example, the polarization and / or the 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 actuating fingers that are inserted at the edge of the radiation beam to correct intensity variations. The spatial extent 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 trivial to modify finger parameters from a known processing design, since such modifications may lead to undesired changes in one or more characteristics of the radiation beam.

[0006]

[0006] In order to achieve acceptable image quality at the patterning device and substrate, an illumination beam with controlled uniformity is desirable. Before reflecting off or passing through the patterning device, the illumination beam typically has a non-uniform intensity profile. At various stages of the lithography process, it is desirable for the illumination beam to be controlled to achieve improved uniformity. Uniformity may refer to a constant intensity over a relevant cross-section of the illumination beam, but may also refer to the ability to control the illuminance to achieve a selected uniformity parameter. The patterning device imparts a pattern to a radiation beam, which is projected onto a substrate. The image quality of this projected beam is affected by the uniformity of the beam.

[0007]

[0007] Therefore, in order to maximize manufacturing capacity and yield rate, minimize manufacturing defects, and reduce cost per device, it is desirable to control illumination uniformity so that lithography tools perform the lithography process as efficiently as possible. Summary of the Invention

[0008] In some embodiments, an illumination adjustment device for adjusting crossed slot illumination of a beam in a lithographic apparatus comprises a plurality of fingers configured to adjust the crossed slot illumination to match a selected intensity profile, each finger having a distal edge comprising at least two segments, the at least two segments forming a notch in the distal edge.

[0009] In some embodiments, a uniformity correction system for adjusting crossed slot illumination of a scanned beam in a lithographic apparatus comprises a plurality of fingers configured to adjust the crossed slot illumination to match a selected intensity profile, each finger having a distal edge with at least two teeth.

[0010]

[0010] In some embodiments, a lithographic apparatus comprises an illumination system, an illumination adjuster, a support, and a projection system. The illumination adjuster comprises a plurality of fingers. Each finger has a distal edge comprising at least two segments, the at least two segments forming an indentation of the distal edge. The illumination system is configured to generate a beam of radiation, the beam comprising intersecting slot illumination. The plurality of fingers are configured to adjust the intersecting slot illumination to match a selected intensity profile. The support is configured to support a patterning device configured to impart a pattern to the beam. The projection system is configured to project the patterned beam of radiation onto a substrate.

[0011]

[0011] Further features and advantages of the present invention, as well as 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 described herein for illustrative purposes only. Based on the teachings contained herein, a person skilled in the art will be able to easily conceive further embodiments. [Brief description of the drawings]

[0012]

[0012] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate the invention and, together with the description, serve to further explain the principles of the invention and to enable those skilled in the art to make and use the invention.

[0013] [Figure 1A]

[0013] FIG. 1 shows a schematic diagram of a reflective lithographic apparatus according to some embodiments. [Figure 1B]

[0014] 1 depicts a schematic diagram of a transmissive lithographic apparatus according to some embodiments; [Diagram 2]

[0015] 2 shows a more detailed schematic diagram of a reflective lithographic apparatus according to some embodiments; [Diagram 3]

[0016] 1 shows a schematic diagram of a lithographic cell according to some embodiments. [Figure 4A-4B]

[0017]

[0018] FIG. 4A shows a schematic diagram of a portion of a uniformity correction system according to some embodiments, and FIG. 4B shows a graph of the intensity of crossed slot illumination according to some embodiments. [Diagram 5]

[0019] 1 shows a schematic diagram of a pupil according to some embodiments. [Figure 6]

[0020] 13A-13C show schematic diagrams of distal edges of fingers used in illumination adjusting devices according to some embodiments. [Figure 7]

[0021] 13 shows a bar graph of the resulting local intensity variation for various pupil and finger geometries in accordance with some embodiments.

[0014]

[0022] The features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the drawings, in which like reference numerals identify corresponding elements throughout. In the drawings, like reference numerals generally indicate identical, functionally similar, and / or structurally similar elements. Moreover, the leftmost digit(s) of a reference number generally identifies the drawing in which the reference number first appears. Unless otherwise indicated, the drawings provided throughout this disclosure should not be construed as drawings to scale. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015]

[0023] This specification discloses one or more embodiments incorporating the features of the present invention. The disclosed embodiment or embodiments are merely exemplary of the present invention. The scope of the present invention is not limited to the disclosed embodiment or embodiments. The present invention is defined by the claims appended hereto.

[0016]

[0024] References to the described embodiments, and to "one embodiment," "an embodiment," "exemplary embodiment," and the like, herein indicate that the described embodiment may include a particular feature, structure, or characteristic, but each embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is understood that it is within the knowledge of one of ordinary skill in the art to implement such feature, structure, or characteristic in connection with other embodiments, whether or not explicitly described.

[0017]

[0025] Spatially relative terms such as "beneath," "below," "lower," "above," "on," "upper," and the like, may be used herein to facilitate describing the relationship of one element or feature to another element or features, as shown in the figures. The spatially relative terms are intended to encompass various orientations of the device in use or operation in addition to the orientation shown in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may be interpreted accordingly.

[0018]

[0026] The term "about" as used herein refers to a given quantity value that may vary based on a particular technique. Based on a particular technique, the term "about" can refer to a given quantity value that varies within a range of, for example, 10-30% of the value (e.g., ±10%, ±20%, or ±30% of the value).

[0019]

[0027] The embodiments of the present disclosure may be implemented in hardware, firmware, software, or any combination thereof. The embodiments of the present disclosure may also be implemented as instructions stored on a machine-readable medium that 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 read-only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, electrical, optical, acoustic, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Furthermore, firmware, software, routines, instructions may be described herein as performing certain operations. However, it will be appreciated that such descriptions are merely for convenience and that such operations may actually result from a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc.

[0020]

[0028] Before describing such embodiments in detail, it will be useful to provide an example environment in which embodiments of the present disclosure can be implemented.

[0021]

[0029] Exemplary Lithography System

[0030] 1A and 1B are schematic diagrams of lithographic apparatus 100 and lithographic apparatus 100', respectively, in which embodiments of the present disclosure may be implemented. Lithographic apparatus 100 and lithographic apparatus 100' respectively comprise the following: an illumination system (illuminator) IL configured to condition a radiation beam B (e.g. deep ultraviolet radiation or extreme ultraviolet radiation), a support structure (e.g. mask table) MT configured to support a patterning device (e.g. mask, reticle, or dynamic patterning device) MA and connected to a first positioner PM configured to accurately position the patterning device MA, and a substrate table (e.g. wafer table) WT configured to hold a substrate (e.g. resist coated wafer) W and connected to a second positioner PW configured to accurately position the substrate W. Lithographic apparatus 100 and 100' also comprise a projection system PS configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (e.g. comprising one or more dies) of the substrate W. In lithographic apparatus 100, the patterning device MA and the projection system PS are reflective. In lithographic apparatus 100', the patterning device MA and the projection system PS are transmissive.

[0022]

[0031] 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 providing 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 a movement of the radiation beam B, and a uniformity compensator UC that allows the illumination slit uniformity to be controlled. The measurement sensor MS may also be arranged elsewhere. For example, the measurement sensor MS may be on or near the substrate table WT.

[0023]

[0032] The support structure MT holds the patterning device MA in a manner that depends on conditions such as an orientation of the patterning device MA relative to a reference frame, the design of at least one of the lithographic apparatuses 100 and 100', and whether or not the patterning device is held in a vacuum environment. The support structure MT may use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterning device MA. The support structure MT may be, for example, a frame or a table, and may be fixed or movable as required. By using sensors the support structure MT can ensure that the patterning device MA is at a desired position, for example with respect to the projection system PS.

[0024]

[0033] The term "patterning device" MA should be interpreted broadly to refer to any device that can be used to impart a pattern to a radiation beam B in its cross-section to create a pattern in a target portion C of a substrate W. The pattern imparted to the radiation beam B may correspond to a particular functional layer in a device being created in the target portion C to form an integrated circuit.

[0025]

[0034] Patterning device MA can be transmissive (as in lithographic apparatus 100' of FIG. 1B) or reflective (as in lithographic apparatus 100 of FIG. 1A). Examples of patterning devices MA include reticles, masks, programmable mirror arrays, or programmable LCD panels. Masks are well known in lithography, and include mask types such as binary, alternating phase-shift, or attenuated phase-shift masks, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted so as to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern to a radiation beam B that is reflected by the matrix of small mirrors.

[0026]

[0035] As used herein, the term "projection system" PS can include any type of projection system, including refractive, reflective, magnetic, electromagnetic, electrostatic, or any combination thereof, appropriate to the exposure radiation used or other factors such as the use of an immersion liquid 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. A vacuum environment may therefore be provided throughout the beam path using a vacuum wall and vacuum pumps.

[0027]

[0036] 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 a "multi-stage" machine, the additional substrate tables WT may be used in parallel, or one or more substrate tables WT may be used for exposure while preparatory steps are carried out on one or more other tables. In some circumstances the additional tables may not be substrate tables WT.

[0028]

[0037] The lithographic apparatus may be of a type in which at least a portion of the substrate may be covered with a liquid having a relatively high refractive index, such as water, so as to fill a space between the projection system and the substrate. Immersion liquids may also be applied to other spaces in the lithographic apparatus, for example between the mask and the projection system. Immersion techniques are well known in the art for increasing the numerical aperture of projection systems. As used herein, the term "immersion" does not mean that a structure such as the substrate must be submerged in liquid, but rather that a liquid is present between the projection system and the substrate during exposure.

[0029]

[0038] 1A and 1B, the illuminator IL receives a radiation beam from a radiation source SO. The source SO and the lithographic apparatus 100, 100' may be separate physical entities, for example if the source SO is an excimer laser. In this case, the source SO is not considered to form part of the lithographic apparatus 100 or 100' and the radiation beam B passes from the source SO to the illuminator IL via a beam delivery system BD (FIG. 1B), for example with suitable directing mirrors and / or beam expanders. In other cases, the source SO may be an integral part of the lithographic apparatus 100, 100', for example if the source SO is a mercury lamp. The source SO and the illuminator IL, together with the beam delivery system BD, if required, may be referred to as a radiation system.

[0030]

[0039] The illuminator IL may comprise an adjuster AD (FIG. 1B) for adjusting the angular intensity distribution of the radiation beam. Generally, 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 may be adjusted. In addition, the illuminator IL may comprise various other components (FIG. 1B), such as an integrator IN and a condenser CO. The illuminator IL can be used to adjust the radiation beam B to obtain a desired uniformity and intensity distribution in its cross-section. The desired uniformity of the radiation beam B can be maintained by using a uniformity compensator UC. The uniformity compensator UC comprises a number of protrusions (e.g. fingers) that can 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.

[0031]

[0040] Referring to FIG. 1A, a radiation beam B is incident on a patterning device (e.g. mask) MA, which is held on a support structure (e.g. mask table) MT, and is patterned by the patterning device. In the lithographic apparatus 100, the radiation beam B is reflected from the patterning device (e.g. mask) MA. After being reflected from the patterning device (e.g. mask) MA, the radiation beam B passes through a projection system PS. The projection system PS 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 accurately moved (e.g. to position a different target portion C in the path of the radiation beam B). Similarly, a first positioner PM and another position sensor IF1 can be used to accurately position the patterning device (e.g. mask) MA with respect to the path of the radiation beam B. Mask alignment marks M1, M2 and substrate alignment marks P1, P2 may be used to align the patterning device (eg mask) MA and substrate W.

[0032]

[0041] Referring to FIG. 1B, a radiation beam B is incident on a patterning device (e.g. mask MA) held on a support structure (e.g. mask table MT) and is patterned by the patterning device. 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 a substrate W. The projection system has a pupil PPU that is conjugate with the illumination system pupil IPU. A portion of the radiation originates from the intensity distribution in the illumination system pupil IPU and traverses the mask pattern without being affected by diffraction at the mask pattern to create an image of the intensity distribution in the illumination system pupil IPU. The desired uniformity of the radiation beam B can be maintained by using a uniformity compensator UC for controlling the uniformity of the radiation beam B. A sensor ES may be used to monitor the uniformity of the radiation beam B.

[0033]

[0042] The projection system PS projects an image MP' of the mask pattern MP. The image MP' is formed on a photoresist layer coated on the substrate W by diffracted beams generated from the mark pattern MP by radiation from the intensity distribution. For example, the mask pattern MP may include an array of lines and spaces. Non-zero order diffraction of radiation at the array generates stimulated diffracted beams redirected perpendicular to the lines. The non-diffracted beams (i.e. the so-called zero order diffracted beams) traverse the pattern without changing their propagation direction. The zero order diffracted beams traverse an upper lens or an upper lens group of the projection system PS upstream of the conjugate pupil PPU of the projection system PS and reach the conjugate pupil PPU. The part of the intensity distribution in the plane of the conjugate pupil PPU associated with the zero order diffracted beam is an image of the intensity distribution in the illumination system pupil IPU of the illumination system IL. The aperture device PD is arranged, for example, in or approximately in a plane containing the conjugate pupil PPU of the projection system PS.

[0034]

[0043] The projection system PS is arranged to capture not only the zeroth order diffracted beam but also the first or higher order diffracted beams (not shown) by means of a lens or lens group L. In some embodiments, the resolution enhancing effect of dipole illumination can be exploited by using a dipole illumination to image a line pattern extending in a direction perpendicular to the line. For example, a first order diffracted beam interferes with a corresponding zeroth order diffracted beam at the level of the wafer W to create an image of the line pattern MP at the highest possible resolution and process window (i.e., usable depth of focus combined with an acceptable exposure dose deviation). In some embodiments, astigmatism can be reduced by providing opposing quadrant poles (not shown) of the illumination system pupil IPU. Furthermore, in some embodiments, astigmatism can be reduced by blocking the zeroth order beam at a conjugate pupil PPU of the projection system associated with the opposing quadrant pole. This is explained in more detail in U.S. Pat. No. 7,511,799 B2, issued Mar. 31, 2009, which is incorporated herein by reference in its entirety.

[0035]

[0044] With the aid 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 accurately moved (e.g. to position a different target portion C in the path of the radiation beam B). Similarly, the mask MA can be accurately positioned with respect to the path of the radiation beam B using the first positioner PM and another position sensor (not shown in FIG. 1B ) (e.g. after mechanical removal of the mask library or during a scan).

[0036]

[0045] In general, movement of the mask table MT may be realized 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 may be realized 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 may be connected to a short-stroke actuator only, or may be fixed. The mask MA and substrate W may be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. The substrate alignment marks as illustrated occupy dedicated target portions, but may also be located in spaces between the target portions (known as scribe-lane alignment marks). Similarly, in situations in which more than one die is provided on the mask MA, the mask alignment marks may be located between the dies.

[0037]

[0046] The mask table MT and patterning device MA may be within a vacuum chamber V. An in-vacuum robot IVR can be used to move the patterning device, such as a mask, in and out of the vacuum chamber V. Alternatively, if the mask table MT and patterning device MA are outside the vacuum chamber, an ex-vacuum robot can be used for various transport operations, similar to the in-vacuum robot IVR. Both the in-vacuum and ex-vacuum robots need to be calibrated for smooth movement of any payload (e.g. a mask) to the fixed kinematic mount of the transfer station.

[0038]

[0047] The depicted lithographic apparatus 100 and 100' can be used in at least one of the following modes:

[0039]

[0048] 1. In step mode, the support structure (e.g. mask table) MT and substrate table WT are kept essentially stationary, while an entire pattern imparted to the radiation beam B is projected onto a target portion C in one go (i.e. a single static exposure), and the substrate table WT is then moved in the X and / or Y direction so that a different target portion C can be exposed.

[0040]

[0049] 2. In scan mode, the support structure (e.g. mask table) MT and the substrate table WT are scanned synchronously while 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 can be determined by the (de-)magnification and image reversal characteristics of the projection system PS.

[0041]

[0050] 3. In another mode, the support structure (e.g. mask table) MT is kept essentially stationary holding a 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 can be used and the programmable patterning device is updated as required after each movement of the substrate table WT, or between successive radiation pulses during a scan. This mode of operation is readily applicable to maskless lithography using a programmable patterning device such as a programmable mirror array.

[0042]

[0051] Combinations and / or variations on the above described modes of use or entirely different modes of use may also be employed.

[0043]

[0052] In a further embodiment, the lithographic apparatus 100 comprises an extreme ultraviolet (EUV) radiation source configured to generate an EUV radiation beam for EUV lithography. Typically, the EUV radiation source is arranged in a radiation system and a corresponding illumination system is configured to condition the EUV radiation beam of the EUV radiation source.

[0044]

[0053] FIG. 2 shows the lithographic apparatus 100 in more detail, comprising a source collector apparatus SO, an illumination system IL, and a projection system PS. The source collector apparatus SO is constructed and arranged such that a vacuum environment can be maintained within an enclosure 220 of the source collector apparatus SO. The EUV radiation emitting plasma 210 can be formed by a discharge produced plasma source. To generate EUV radiation, a very hot plasma 210 can be generated by a gas or vapor, such as, for example, Xe gas, Li vapor, or Sn vapor, emitting radiation in the EUV range of the electromagnetic spectrum. The very hot plasma 210 can be generated, for example, by an electric discharge, producing at least a partially ionized plasma. For efficient radiation generation, a partial pressure of, for example, 10 Pa of Xe, Li, Sn vapor, or any other suitable gas or vapor may be required. In some embodiments, a plasma of excited tin (Sn) is provided to generate the EUV radiation.

[0045]

[0054] Radiation emitted by the high temperature plasma 210 is delivered from the source chamber 211 into the collector chamber 212 via an optional gas barrier or contaminant trap 230 (sometimes also referred to as a contaminant barrier or foil trap) positioned in or behind an opening in the source chamber 211. The contaminant trap 230 may include a channel structure. The contaminant trap 230 may include a gas barrier or a combination of a gas barrier and a channel structure. The contaminant trap or contaminant barrier 230 further illustrated herein includes at least a channel structure.

[0046]

[0055] The collector chamber 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 off a grating spectral filter 240 and focused into a virtual source point IF. The virtual source point IF is commonly referred to as an intermediate focus, and the source collector arrangement is positioned such that the intermediate focus IF is at or near the opening 219 of the enclosure structure 220. The virtual source point IF is an image of the radiation emitting plasma 210. The grating spectral filter 240 is used in particular to suppress infrared (IR) radiation.

[0047]

[0056] The radiation then traverses an illumination system IL, which may comprise a faceted field mirror device 222 and a faceted pupil mirror device 224 arranged to provide a desired angular distribution of the radiation beam 221 at the patterning device MA and to provide a desired radiation intensity uniformity at the patterning device MA. Upon reflection of the radiation beam 221 off the patterning device MA, which is held by the support structure MT, a patterned beam 226 is formed which is imaged by the projection system PS via reflective elements 228, 229 onto the substrate W held by a wafer stage or substrate table WT.

[0048]

[0057] Generally, there may be more elements in the illumination optics unit IL and the projection system PS than are shown. A grating spectral filter 240 may optionally be present depending on the type of lithographic apparatus. Furthermore, there may be more mirrors than shown in Figure 2, for example there may be one to six additional reflective elements in the projection system PS compared to what is shown in Figure 2.

[0049]

[0058] In some embodiments, the illumination optics unit IL may include a sensor ES providing measurements of one or more of, for example, energy per pulse, photon energy, intensity, average power, etc. The illumination optics unit IL may include a measurement sensor MS for measuring the movement of the radiation beam B, and a uniformity compensator UC that allows the illumination slit uniformity to be controlled. The measurement sensor MS may also be arranged elsewhere. For example, the measurement sensor MS may be on or near the substrate table WT.

[0050]

[0059] 2 is shown as a nested collector with grazing incidence reflectors 253, 254, and 255, just as an example of a collector (or collector mirror). Grazing incidence reflectors 253, 254, and 255 are arranged axially symmetrically about optical axis O, and this type of collector system CO is suitable for use in combination with a discharge produced plasma source, often referred to as a DPP source.

[0051]

[0060] Exemplary Lithography Cell

[0061] FIG. 3 shows a lithography cell 300, sometimes called a lithocell or cluster, according to some embodiments. The lithography apparatus 100 or 100′ may form part of the lithography cell 300. The lithography cell 300 may also include one or more devices for performing pre-exposure 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 bake plate BK. A substrate handler, or robot RO, picks up substrates from input / output ports I / O1, I / O2, moves them between the various process devices, and delivers them to a loading bay LB of the lithography apparatus 100 or 100′. Collectively, these devices are often referred to as a track, and are under the control of a track control unit TCU. The TCU is itself controlled by a supervisory control system SCS, which also controls the lithography apparatus via a lithography control unit LACU. These various devices may thus be operated to maximize throughput and processing efficiency.

[0052]

[0062] Exemplary Uniformity Correction System

[0063] 4A illustrates a portion of a uniformity correction system 400 (e.g., uniformity compensator UC of FIGS. 1A, 1B, and 2) according to some embodiments. In some embodiments, the uniformity correction system 400 includes one or more sensors 402 (e.g., sensor ES, FIGS. 1A, 1B, and 2) and a plurality of uniformity compensator elements 404 (e.g., fingers). Each of the uniformity compensator elements 404 includes a distal edge 406.

[0053]

[0064] 4A shows the crossed slot illumination 408 (e.g., a cross-section of an illumination beam or an illumination slit). The crossed slot illumination 408 is represented as a 2D intensity map having various intensity regions 410, 412, and 414. For example, intensity region 410 has a low relative intensity and is disposed at an outer portion of the crossed slot illumination 408. Conversely, intensity region 414 has a high relative intensity and is disposed toward a central portion of the crossed slot illumination 408. In some embodiments, the crossed slot illumination 408 is generated by using a pupil system (not shown) upstream of the uniformity correction system 400 and scanning the beam.

[0054]

[0065] In some embodiments, the shape of the intersecting slot illumination 408 has a substantially arcuate geometry. Each distal edge 406 comprises a straight distal edge oriented to generally follow the curvature of the arcuate geometry. In some embodiments, the shape of the intersecting slot illumination 408 has a substantially rectangular geometry (not shown) and each distal edge comprises a straight edge oriented to generally follow the shape of the rectangular geometry. Each of the uniformity compensator elements 404 is attached to a corresponding actuator.

[0055]

[0066] In some embodiments, the spacing (e.g., pitch or finger pitch) between the centers of each of the uniformity compensator elements 404 along the X direction is approximately between 1-7 mm. The reference XY coordinates provided in FIG. 4A are for ease of discussion and are not limiting. In some embodiments, the pitch of the uniformity compensator elements 404 along the X direction is approximately 4 mm.

[0056]

[0067] The uniformity compensator elements 404 can be fabricated by a variety of fabrication techniques. For example, in some embodiments, the uniformity compensator elements 404 can be fabricated using electrical discharge machining (EDM).

[0057]

[0068] In some embodiments, the uniformity correction system 400 can modify or adjust an illumination beam used in a lithography operation. For example, each of the uniformity compensator elements 404 in the path of the illumination beam (e.g., at least the overlapping crossed slot illuminations 408) can be adjusted using a corresponding actuator to match the intensity profile of the crossed slot illuminations 408 to a selected intensity profile. Examples of the operation of the uniformity compensator 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, both of which are incorporated herein by reference in their entireties.

[0058]

[0069] 4B shows a graph 416 of the intensity of the cross slot illumination 408 according to some embodiments. The vertical axis of the graph 416 represents the scan-integrated intensity I(x) of the cross slot illumination 408. In relation to the scan integration, the intensity of the cross slot illumination 408 can be described in XY coordinates, e.g., I(x,y). This 2D representation can be reduced to a 1D representation of I(x) (e.g., line power, irradiance, or intensity) by integrating along the so-called scan direction. If the intensity variation along the X direction is of interest, then a scan integration is performed in the Y direction, as shown in the following equation:

[0059]

number

[0060]

[0070] The horizontal axis of the graph 416 represents the position of the crossed slot illumination 408 corresponding to a given X-coordinate. A perpendicular line 418 is provided to clarify the correlation between the intensity of the crossed slot illumination 408 and a given X-coordinate. Plot 420 represents an example scan-integrated intensity profile without the uniformity correction system 400 (e.g., the uniformity compensator element 404 is removed from the path of the illumination beam). At least two types of non-uniformities (e.g., non-flat lines) are discernible in the plot 420: (1) an overall trend resembling a spherical mountain, and (2) local intensity variations (e.g., small variations having a spatial frequency between approximately 3-5 mm). Local intensity variations may also be referred to herein as short-range or high-frequency (spatial) variations. To ensure image quality when performing a lithography process using the crossed slot illumination 408, it is important to reduce the two non-uniformities.

[0061]

[0071] In some embodiments, the spherical peak non-uniformity is addressed by using a uniformity correction system 400 for the crossed slot illumination 408. For example, a uniformity compensator element 404 can be inserted and adjusted in the path of the illumination beam to produce the scan integrated intensity profile represented by plot line 422. The scan integrated intensity profile represented by plot line 424 is then desired for the lithography process. Plot line 424 shows the reduction or prevention of local intensity variations (e.g., making the intensity more uniform). Plot line 422 can be produced by using a distal edge 406 with a straight distal edge 426 and / or a chamfered (or beveled) edge 428 oriented to generally follow the geometry of the crossed slot illumination 408. Here, the dotted structure represents an alternative version of the distal edge 426 depicted as a single solid line.

[0062]

[0072] The local intensity variations visible in plots 420 and 422 can be exacerbated by, for example, the spacing between finger centers (i.e., pitch), pupil configuration, intensity gradient, and finger shape. Finger pitch and pupil configuration are related. Pupil configuration refers to the arrangement of one or more illumination apertures upstream of the uniformity correction system and should not be confused with crossed slot illumination 408.

[0063]

[0073] A pupil may have one or more apertures having a particular size, shape, and arrangement. FIG. 5 illustrates pupils 500, 504, and 508 according to some embodiments. The XY coordinate system illustrated in FIG. 5 is intended to match the coordinates of FIGS. 4A and 6 for ease of discussion, and may or may not match other figures or illustrations. In some embodiments, pupil 500 includes two apertures 502 spaced apart by a distance d1 along the X direction. The shape of apertures 502 is elliptical or elliptical-like. The major axes of apertures 502 are generally aligned along the Y direction. In some embodiments, pupil 504 includes two apertures 506 spaced apart by a distance d2 along the Y direction. The shape of apertures 506 is elliptical or elliptical-like. The major axes of apertures 506 are generally aligned along the X direction. Having a two-aperture arrangement, pupil 500 and pupil 504 may be described by the term "dipole" (e.g., dipole pupil). In some embodiments, pupil 508 includes four apertures 510. The apertures 510 are arranged in a rectangular array. The apertures 510 are arranged such that two apertures are separated by a distance d3 along the X direction and two apertures are separated by a distance d4 along the Y direction. The shape of the apertures 506 has at least three-fold symmetry or more (e.g., a circle has infinite axes of symmetry). Having a four-aperture arrangement, the pupil 508 may be described by the term "quadrupole" (e.g., a quadrupole pupil). Other pupil configurations (e.g., aperture shapes, number of apertures, sizes, spatial arrangements, etc.) are possible but are too numerous to list individually. A suitable pupil configuration can reduce the critical dimension of the imaged structure.

[0064]

[0074] As mentioned above, the finger pitch and pupil configuration are related. Referring again to FIG. 4A, a problem arises when the pitch of the uniformity compensator elements 404 matches the spacing of the pupil aperture along the pitch direction used to generate the illumination beam (e.g., d1 of pupil 500 in FIG. 5). If the pitch of the uniformity compensator elements 404 is substantially similar to d1, the local intensity variations are exacerbated by light leakage between the fingers, and the resulting intensity profile resembles that of plot lines 420 and 422. It would be reasonable for a person skilled in the art to try to solve this problem by changing the finger pitch to be substantially different from d1. However, it is not trivial to modify the finger parameters from the known processing design. For example, software modeling can show that changing the finger pitch produces inconsistent results and in some cases amplifies the local intensity variations rather than promoting uniformity. Software modeling can be performed using, for example, ray modeling and / or MATLAB, among others.

[0065]

[0075] Besides modifying the finger pitch, there are other ways that uniformity can be improved more consistently. For example, it can be shown that modifying the shape of the distal edges of the fingers can improve uniformity across various pupil configurations.

[0066]

[0076] 6 illustrates a distal edge 602 of a finger used in an illumination adjustment device 600 (e.g., a uniformity correction system) according to some embodiments. In some embodiments, the distal edge 602 comprises at least two segments (facets) joined at one vertex. In some embodiments, the distal edge 602 may comprise at least four, eight, or ten segments. In some embodiments, the distal edge 602 comprises at least two, three, four, five, six, seven, eight, or nine vertices.

[0067]

[0077] In some embodiments, the distal edge 602 comprises segments 604, 606, 608, 610, and 612. The distal edge 602 further comprises segments 614, 616, 618, 620, and 622 that correspond to segments 604, 606, 608, 610, and 612. This correspondence is a mirror correspondence about a center line of symmetry 624. The center line of symmetry 624 passes through a central location of the distal edge 602. The distal edge 602 further comprises vertices 626, 628, 630, and 632. The segments 604, 606, 608, 610, and 612 are joined at vertices 626, 628, 630, and 632 as shown in FIG. 6. The distal edge 602 further comprises vertices 636, 638, 640, and 642. Vertices 636, 638, 640, and 642 correspond to mirror images of vertices 626, 628, 630, and 632 about vertex 634 and centerline of symmetry 624. Segments 614, 616, 618, 620, and 622 are joined at vertices 636, 638, 640, and 642, as shown in Figure 6. The group of segments 604, 606, 608, 610, and 612 is joined with the group of segments 614, 616, 618, 620, and 622 at vertex 634.

[0068]

[0078] In some embodiments, segments 604, 606, 608, 610, 612, 614, 616, 618, 620, and 622 may each be curved or straight. Vertices 626, 628, 630, 632, 634, 636, 638, 640, and 642 may each be acute or curved.

[0069]

[0079] In some embodiments, the illumination adjustment device 600 is configured to adjust the cross slot illumination 646 of a beam in a lithography apparatus. To adjust or correct the uniformity of the cross slot illumination 646, a portion of the distal edge 602 may be protruding (e.g., teeth) or recessed. Software modeling indicates that a geometry of at least one indentation or at least two teeth can improve the uniformity of the cross slot illumination. Thus, in some embodiments, at least two segments of the distal edge 602 are joined at an apex to form the indentation of the distal edge 602 (e.g., segments 606 and 608 joined at apex 628, or segments 610 and 612 joined at apex 632). In some embodiments, the distal edge 602 comprises at least four segments forming at least two indentations of the distal edge 602. In some embodiments, the distal edge 602 comprises at least six segments forming at least three indentations of the distal edge 602. In some embodiments, distal edge 602 includes at least eight segments forming at least four notches on distal edge 602. For simplicity, apexes 628, 632, 638, and 642 may be referred to as notches and apexes 626, 630, 634, 636, and 640 may be referred to as teeth. In some embodiments, distal edge 602 includes at least three, four, or five teeth.

[0070]

[0080] In some embodiments, the width of the distal edge 602 is between approximately 2-12 mm. In some embodiments, the width of the distal edge 602 is approximately 7 mm. The term "width" is used herein to characterize the extent of the distal edge 602 in the X-direction according to the coordinates shown in FIG. 6.

[0071]

[0081] By repeating the fingers, multiple fingers can be constructed for the illumination adjustment device 600, with each finger having a distal edge 602. In some embodiments, the pitch of the fingers of the illumination adjustment device 600 is between approximately 1-7 mm. In some embodiments, the pitch of the fingers of the illumination adjustment device 600 is approximately 4 mm.

[0072]

[0082] The overall orientation of the distal edge 602 with each finger iteration is such that the distal edge 602 is substantially aligned with the geometry of the cross slot illumination 646. Previously, in connection with FIG. 4, the distal edge 426 was shown to be aligned with the local edge of the cross slot illumination 408 (FIG. 4A). Similarly, the cross slot illumination 646 may have a substantially arc-shaped geometry. In some embodiments, the cross slot illumination 646 may have a substantially rectangular geometry. Thus, the orientation of the symmetric centerline 624 (along Y) shown in FIG. 6 should not be construed as limiting. In some embodiments, the symmetric centerline 624 is oriented perpendicular to the local edge of the cross slot illumination. For example, the symmetric centerline 624 may be slanted if the distal edge 602 is slanted similar to the distal edge 426 of FIG. 4. In some embodiments, the distal edge 602 may be substantially asymmetric.

[0073]

[0083] The distal edge 602 can be fabricated by a variety of shaping techniques. For example, in some embodiments, the distal edge 602 can be fabricated by electrical discharge machining (EDM).

[0074]

[0084] In some embodiments, ray modeling and / or MATLAB may be used in combination with a global optimization algorithm (e.g., Monte Carlo) and solver to determine finger geometries (e.g., distal edges 602) that can improve cross-slot illumination uniformity.

[0075]

[0085] FIG. 7 illustrates a bar graph 700 of the resulting local intensity variation for various pupil and finger geometries according to some embodiments. The data for bar graph 700 was generated using the software modeling described above for various permutations of pupil and finger geometries. The bins on the horizontal axis of bar graph 700 represent various pupils. For example, bin 708 (also referred to as "dipole X") corresponds to a pupil with dipole apertures distributed along the X direction (e.g., pupil 500, FIG. 5). bin 710 (also referred to as "dipole Y") corresponds to a pupil with dipole apertures distributed along the Y direction (e.g., pupil 504, FIG. 5). And bin 712 corresponds to a pupil with quadrupole apertures distributed in a square pattern (e.g., pupil 508).

[0076]

[0086] The vertical axis of bar graph 700 represents the maximum local intensity variation expressed as a percentage value. To clarify the units of the vertical axis of bar graph 700, refer to plot lines 422 and 420 and line 430 of FIG. 4B. The important parameter of the local intensity variation is the maximum difference (shown by line 430). In some embodiments, the maximum difference of 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 plot line 422 and multiplied by 100 to arrive at the percentage units shown in bar graph 700. It can be seen that the nominal intensity is approximately 1.94 (arbitrary units), as shown by plot line 424. The nominal intensity can be the average of plot lines 422 or 424, or the global minimum of plot line 420. Those skilled in the art will appreciate that there are several ways to determine the percentage-based local intensity variation. For example, a smoothing algorithm (e.g., a moving average) may be applied to plot line 422 to arrive at plot line 424. The local intensity variation may then be determined as a function of the X coordinate by comparing the values ​​of plot lines 422 and 424. The maximum local intensity variation may then be extracted from the resulting LIF(x).

[0077]

[0087] In bar graph 700, bars 702n, 704n, and 706n (white bars) represent the maximum local intensity variation caused by using an illumination adjustment device with finger geometry that does not have a notched distal edge (e.g., distal edge 426, FIG. 4A ). Bars 702i, 704i, and 706i (shaded bars) represent the maximum local intensity variation caused by using an illumination adjustment device with finger geometry that has a notched distal edge, specifically distal edge 602 shown in FIG.

[0078]

[0088] In bin 708 with bars 702n and 702i, it is seen that the maximum local intensity variation is reduced from approximately 0.30% to approximately 0.24% by using the notched (or toothed) distal edge fingers, a reduction of roughly 20% relative to the non-notched (or toothless) distal edge. Using a notched distal edge geometry also reduces the maximum local intensity variation when using a dipole Y (illustrated by bars 704n and 704i) or quadrupole pupil (illustrated by bars 706n and 706i). Thus, embodiments of the present disclosure provide structures and methods for improving the uniformity of crossed slot illumination of beams in a lithographic apparatus.

[0079]

[0089] In some embodiments using fingers with notched distal edges, the local intensity variation of the crossed slot illumination is reduced by at least 5%, 10%, or 20% relative to results when non-notched distal edges are used. In some embodiments using fingers with notched distal edges, the local intensity variation of the crossed slot illumination is reduced by at least 0.02%, 0.04%, or 0.06% relative to the nominal intensity of the crossed slot illumination.

[0080]

[0090] Embodiments may also be described using the following clauses. 1. An illumination adjustment device for adjusting crossed slot illumination of beams in a lithography apparatus, comprising: a plurality of fingers configured to adjust the cross slot illumination to match a selected intensity profile; Each finger has a distal edge with at least two segments; At least two of the segments form a notch on the distal edge. 2. A light intensity control device as claimed in clause 1, wherein at least two of the segments are straight and / or curved. 3. An illumination adjustment device as claimed in claim 1, wherein at least a portion of the distal edge is symmetrical about a line of symmetry passing through a central position of the distal edge. 4. The illumination control device of clause 1, wherein the distal edge comprises at least four segments, the at least four segments forming at least two notches in the distal edge. 5. The illumination control device of clause 1, wherein the distal edge comprises at least eight segments, the at least eight segments forming at least four notches in the distal edge. 6. The illumination control device of clause 1, wherein the cross slot illumination has a substantially rectangular geometry. 7. The illumination control device of clause 1, wherein the cross slot illumination has a substantially arc-shaped geometry. 8. The illumination adjusting device of clause 1, wherein the plurality of fingers are attached to a corresponding plurality of actuators configured to independently move each of the plurality of fingers to adjust the cross slot illumination. 9. A uniformity correction system for adjusting a crossed slot illumination of a scanning beam in a lithography apparatus, comprising: a plurality of fingers configured to adjust the cross slot illumination to match a selected intensity profile; A uniformity correction system, wherein each finger has a distal edge with at least two teeth. 10. The uniformity correction system of clause 9, wherein at least two teeth have straight and / or curved segments of distal edges. 11. The uniformity correction system of clause 9, wherein at least a portion of the distal edge is symmetrical about a line of symmetry passing through a central location of the distal edge. 12. A uniformity correction system according to clause 9, wherein the distal edge has at least four teeth. 13. A uniformity correction system as in clause 9, wherein at least two teeth are joined at an apex, whereby the apex forms a distal edge notch. 14. The uniformity correction system of clause 9, wherein the crossed slot illumination has a substantially rectangular geometry. 15. The uniformity correction system of clause 9, wherein the crossed slot illumination has a substantially arc-shaped geometry. 16. The uniformity correction system of clause 9, wherein the plurality of fingers are attached to a corresponding plurality of actuators configured to independently move each of the plurality of fingers to adjust the cross slot illumination. 17. An illumination system configured to generate a radiation beam comprising crossed slot illumination; An illuminance adjusting device, a plurality of fingers configured to adjust the cross slot illumination to match a selected intensity profile; Each finger has a distal edge with at least two segments; an illumination control device, the at least two segments forming a notch on a distal edge; a support configured to support a patterning device configured to impart a pattern to the beam; and a projection system configured to project the patterned beam onto a substrate; and 1. A lithographic apparatus comprising: 18. The lithography apparatus of clause 17, wherein the distal edge comprises at least four segments, the at least four segments forming the at least two indentations in the distal edge. 19. The lithography apparatus of clause 17, wherein the distal edge comprises at least eight segments, the at least eight segments forming at least four indentations in the distal edge. 20. Local intensity variations in cross-slot illumination are due to light leakage between multiple fingers; 18. The lithographic apparatus of clause 17, wherein local intensity variations are reduced by approximately at least 0.02% relative to a nominal intensity of the crossed slot illumination.

[0081]

[0091] Although particular reference is made herein to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein has other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, LCDs, thin film magnetic heads, and the like. In light of these alternative applications, those skilled in the art will recognize that the use of the terms "wafer" or "die" herein may be considered synonymous with the more general terms "substrate" or "target portion", respectively. The substrates described herein may be processed, before or after exposure, for example in a track (a tool that typically applies a layer of resist to the substrate and develops the exposed resist), a metrology tool, and / or an inspection tool. Where appropriate, the disclosure herein may be applied to these and other substrate processing tools. Furthermore, the substrate may be processed multiple times, for example to produce a multi-layer IC, and thus the term substrate as used herein may also refer to a substrate that already includes multiple processed layers.

[0082]

[0092] Although particular reference has been made to the use of embodiments of the invention in the field of optical lithography, it should be understood that the invention may also be used in other fields, for example imprint lithography, depending on the context, and is not limited to optical lithography. In imprint lithography, a topography in a patterning device defines the pattern created on a substrate. The topography of the patterning device is imprinted into a layer of resist supplied to the substrate and the resist is cured by application of electromagnetic radiation, heat, pressure or a combination thereof. The patterning device is then removed from the resist leaving a pattern in it once the resist has hardened.

[0083]

[0093] It is to be understood that the phraseology or terminology used herein is for the purpose of description and not of limitation, and thus, the terminology or terminology used herein should be interpreted by one of skill in the art in light of the disclosure herein.

[0084]

[0094] Terms such as "illuminance adjustment device," "radiation correction system," and the like may be used herein to describe devices that adjust one or more characteristics of a radiation beam. For example, a uniformity correction system may be referred to as an illumination adjustment device.

[0085]

[0095] Terms such as "radiation", "beam", "light", "illumination" and the like as used herein may encompass any type of electromagnetic radiation, such as, for example, 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 5-20 nm, such as 13.5 nm), or hard x-ray operating below 5 nm, as well as particle beams such as ion beams or electron beams. Generally, radiation having a wavelength between about 400 nm and about 700 nm is considered visible radiation. Radiation having a wavelength between about 780-3000 nm (or greater) is considered infrared radiation. UV generally refers to radiation with wavelengths between 100-400 nm. Within lithography, the term "UV" also applies to wavelengths that may be produced by mercury discharge lamps, namely G-line 436 nm, H-line 405 nm, and / or I-line 365 nm. Vacuum UV, or VUV (i.e. UV absorbed by gases), generally refers to radiation having a wavelength between 100 and 200 nm. Deep UV (DUV) generally refers to radiation having a wavelength ranging from 126 nm to 428 nm, and in some embodiments, excimer lasers can generate DUV radiation for use in lithographic apparatus. It should be understood that radiation having a wavelength in the range of, for example, 5-20 nm, relates to radiation having a certain wavelength band, at least a portion of which is within the range of 5-20 nm.

[0086]

[0096] The term "substrate" as used herein describes a material onto which a layer of material is added. In some embodiments, the substrate itself may be patterned, and the material added onto it may also be patterned or may remain unpatterned.

[0087]

[0097] Although specific reference may be made in this text to the use of the apparatus and / or system according to the invention in the manufacture of ICs, it should be explicitly understood that such an apparatus and / or system has many other possible applications, such as in integrated optical systems, guidance and detection patterns for magnetic domain memories, LCD panels, thin film magnetic heads, etc. In light of these alternative applications, those skilled in the art will recognize that any use of the terms "reticle," "wafer," or "die" herein may be considered synonymous with the more general terms "mask," "substrate," or "target portion," respectively.

[0088]

[0098] While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. This description is not intended to limit the invention.

[0089]

[0099] It is understood that the "Description of the Invention" section is intended to be used to interpret the claims, rather than the "Summary" and "Abstract" sections. The "Summary" and "Abstract" sections may describe one or more exemplary embodiments of the invention as envisioned by the inventors, but cannot describe all exemplary embodiments, and thus are not intended to limit the scope of the invention and the appended claims in any way.

[0090]

[0100] The present invention has been described above using functional components and their relationships that illustrate specific functional examples. The boundaries of these functional components are arbitrarily defined in this specification for the convenience of description. Alternative boundaries can be defined as long as the specific functions and their relationships are appropriately performed.

[0091]

[0101] The foregoing description of specific embodiments fully discloses the general nature of the present invention, such that those skilled in the art can, without undue experimentation, readily modify and / or adapt such specific embodiments to various applications without departing from the general concept of the present invention. Accordingly, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein.

[0092]

[0102] 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. 1. An illumination adjustment device for adjusting crossed slot illumination of beams in a lithography apparatus, comprising: a plurality of fingers configured to adjust the cross slot illumination to match a selected intensity profile; Each finger has a distal edge with at least two segments; The at least two segments form an indentation in the distal edge.

2. The illumination adjusting device of claim 1 , wherein the at least two segments are straight and / or curved.

3. The illumination adjusting device of claim 1 , wherein at least a portion of the distal edge is symmetrical about a line of symmetry passing through a central location of the distal edge.

4. the distal edge comprises at least four segments; The illumination control device of claim 1 , wherein the at least four segments form at least two indentations in the distal edge.

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

6. The illumination control device of claim 1 , wherein the intersecting slot illuminators have a substantially rectangular geometry.

7. The illumination control device of claim 1 , wherein the intersecting slot illuminators have a substantially arc-shaped geometry.

8. 2. The illumination adjusting device of claim 1, wherein the plurality of fingers are attached to a corresponding plurality of actuators configured to independently move the each of the plurality of fingers to adjust the cross slot illumination.

9. 1. A uniformity correction system for adjusting a crossed slot illumination of a scanning beam in a lithographic apparatus, comprising: a plurality of fingers configured to adjust the cross slot illumination to match a selected intensity profile; A uniformity correction system, wherein each finger has a distal edge with at least two teeth.

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 passing through a central location of the distal edge.

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

13. The uniformity correction system of claim 9 , wherein the at least two teeth are joined at an apex, whereby the apex forms a notch in the distal edge.

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

15. The uniformity correction system of claim 9 , wherein the crossed slot illumination comprises a substantially arc-shaped geometry.

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

17. an illumination system configured to generate a radiation beam comprising crossed slot illumination; an illumination adjustment device comprising a plurality of fingers configured to adjust the cross slot illumination to conform to a selected intensity profile, each finger having a distal edge comprising at least two segments, the at least two segments forming an indentation of the distal edge; a support configured to support a patterning device configured to impart a pattern to the beam; and a projection system configured to project the patterned beam onto a substrate; and A lithographic apparatus comprising:

18. the distal edge comprises at least four segments; The lithographic apparatus of claim 17 , wherein the at least four segments form at least two indentations in the distal edge.

19. the distal edge comprises at least eight segments; The lithographic apparatus of claim 17 , wherein the at least eight segments form at least four indentations in the distal edge.

20. the local intensity variation of the cross slot illumination is based on light leakage between the plurality of fingers; 18. The lithographic apparatus of claim 17, wherein the local intensity variations are reduced by approximately at least 0.02% relative to a nominal intensity of the crossed slot illumination.

Images