Multi-stage optical device with constant magnification and telecentric converter

Abstract

A pre-alignment system includes a common objective lens set configured to collect a diffracted beam from a patterning device, wherein the common objective lens set is further configured to produce telecentricity in object space of the pre-alignment system. The pre-alignment system also includes a multipath sensing array having at least one image lens system, wherein the at least one image lens system includes a telecentric converter lens configured to produce telecentricity in image space of the pre-alignment system.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 897,675, filed on September 9, 2019, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to alignment apparatus and systems, such as alignment sensor apparatus for lithographic apparatus and systems. Background Art

[0004] A lithographic apparatus is a machine that applies a desired pattern to a substrate (typically onto a target portion of the substrate). Lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In this case, a patterning device (alternatively called a mask or reticle) is used to produce the circuit pattern to be formed on a single layer of the IC. This pattern can be transferred to a target portion (e.g., a portion including a die, a die, or several dies) on a substrate (e.g., a silicon wafer). Transfer of the pattern is typically performed by imaging onto a layer of radiation-sensitive material (resist) disposed on the substrate. Typically, a single substrate will contain a network of adjacent target portions patterned sequentially. Known lithographic apparatus include so-called steppers, which irradiate each target location by exposing the entire pattern to the target location at once, and so-called scanners, which irradiate each target location by scanning a radiation beam across the pattern in a given direction (the "scanning" direction) while simultaneously scanning the target location parallel or antiparallel to the scan direction. Patterns can also be transferred from a patterning device to a substrate by printing the pattern onto the substrate.

[0005] During a lithography operation, different processing steps may require different layers to be sequentially formed on a substrate. Therefore, the substrate may need to be positioned with high accuracy or precision relative to a previous pattern formed on the substrate. Typically, alignment marks are placed on the substrate to be aligned and positioned relative to a second object. The lithographic apparatus may use an alignment device to detect the position of the alignment marks and use the alignment marks to align the substrate to ensure accurate exposure from the mask. Misalignment between alignment marks at two different layers is measured as overlay error.

[0006] Therefore, there is a need for a system and method that provides alignment with high accuracy and low variability. Summary of the Invention

[0007] Embodiments of a pre-alignment system are described in this disclosure.

[0008] One aspect of the present disclosure provides a pre-alignment system comprising a common objective lens set configured to collect a diffracted beam from a patterning device, wherein the common objective lens set is further configured to produce telecentricity in an object space of the pre-alignment system. The pre-alignment system also comprises a multipath sensing array having at least one image lens system, wherein the at least one image lens system comprises a telecentric converter lens configured to produce telecentricity in an image space of the pre-alignment system.

[0009] In some embodiments, the telecentric converter lens comprises a single optical lens. In some embodiments, the telecentric converter lens comprises glass, crystal, or plastic. In some embodiments, the telecentric converter lens is formed by CNC cutting, including hot air jet cutting, water jet cutting, and laser cutting.

[0010] In some embodiments, the pre-alignment system further comprises a light source configured to illuminate the patterning device at an oblique angle.

[0011] In some embodiments, the pre-alignment system further comprises a beam splitter configured to split the diffracted beam into two or more diffracted beamlets.

[0012] In some embodiments, the pre-alignment system further comprises a detector for each of the at least one image lens system, wherein the detector is configured to generate a pre-alignment signal based on the diffracted beam.

[0013] Another aspect of the present disclosure provides a lithographic apparatus comprising an illumination system configured to condition a radiation beam, a support structure configured to support a pattern forming device, a substrate table configured to hold a substrate, a projection system configured to project a pattern imparted to the radiation beam by the pattern forming device onto a target portion of the substrate, and a first positioner and a second positioner configured to position the pattern forming device and the substrate, respectively. The first positioner comprises a pre-alignment system having at least two channels. The pre-alignment system comprises a common objective lens group configured to collect a diffracted beam from the pattern forming device and generate telecentricity in an object space of the pre-alignment system. The pre-alignment system further comprises a multi-path sensing array having at least one image lens system. The at least one image lens system comprises a telecentric converter lens configured to generate telecentricity in an image space of the pre-alignment system. The pre-alignment system further comprises a detector for each image lens system in the at least one image lens system, wherein the detector is configured to generate a pre-alignment signal based on the diffracted beam.

[0014] Other 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. These embodiments are presented 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

[0015] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the present invention and, together with the description, serve to explain the principles of the invention and to enable one skilled in the relevant art to make and use the invention.

[0016] Figure 1A is a schematic diagram of a reflective lithography apparatus according to an exemplary embodiment.

[0017] Figure 1B is a schematic diagram of a transmissive lithography apparatus according to an example embodiment.

[0018] Figure 2 is a more detailed schematic diagram of a reflective lithography apparatus according to an exemplary embodiment.

[0019] Figure 3 is a schematic diagram of a lithography cell according to an example embodiment.

[0020] Figure 4 The diagram illustrates a pre-alignment system configured to pre-align a patterning device according to an embodiment of the present disclosure.

[0021] Figure 5 An exemplary doubly telecentric optical system is shown according to an embodiment of the present disclosure.

[0022] Figure 6 The diagram illustrates a pre-alignment system with dual telecentricity according to an embodiment of the present disclosure.

[0023] The features and advantages of the present invention will become apparent from the following detailed description, which is set forth in conjunction with the accompanying 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. Additionally, the left-most digit of a reference numeral generally identifies the drawing in which the reference numeral first appears. Unless otherwise indicated, the drawings provided throughout this disclosure should not be construed as being drawn to scale. DETAILED DESCRIPTION

[0024] This specification discloses one or more embodiments that incorporate the features of the present invention. The disclosed embodiments are intended to illustrate the present invention only. The scope of the present invention is not limited to the disclosed embodiments. The present invention is defined by the claims appended hereto.

[0025] The described embodiments and references to "one embodiment," "an embodiment," "an exemplary embodiment," etc. indicate that the described embodiments may include a particular feature, structure, or characteristic, but not every embodiment needs to include the particular feature, structure, or characteristic. Moreover, these words or 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 such feature, structure, or characteristic in conjunction with other embodiments, whether or not the other embodiments are explicitly described.

[0026] For ease of description, spatially relative terms, such as "below," "beneath," "above," "above," and the like, may be used herein to describe the relationship of one element or feature to other elements or features in the drawings. Spatially relative terms are intended to encompass different orientations of the apparatus or 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 should be interpreted accordingly.

[0027] As used herein, the term "approximately" refers to a value of a given quantity that may vary based on the particular technology. Based on the particular technology, the term "approximately" may refer to a value of a given quantity that varies, for example, by 10%-30% above or below the stated value (e.g., ±10%, ±20%, or ±30% of the stated 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 on a machine-readable medium, which can 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; electrically, optically, acoustically, or in other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and the like. Furthermore, firmware, software, routines, and / or instructions may be described herein as performing specific actions. However, it should be understood that such descriptions are for convenience only and that such actions actually result from a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc.

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

[0030] Exemplary lithography systems

[0031] Figure 1A and Figure 1B Schematic illustrations of a lithographic apparatus 100 and a lithographic apparatus 100', respectively, in which embodiments of the present invention may be implemented. The lithographic apparatus 100 and the lithographic apparatus 100' each comprise 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., a mask table) MT configured to support a patterning device (e.g., a 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., 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 the lithographic apparatus 100 ′ further have a projection system PS configured to project a pattern imparted by the patterning device MA to the radiation beam B onto a target portion C (e.g., comprising one or more dies) of a substrate W. In the lithographic apparatus 100 , the patterning 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 for directing, shaping or controlling the radiation beam B, such as refractive, reflective, catadioptric, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof.

[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 can use mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning device MA. The support structure MT can be, for example, a frame or a table, and the support structure MT can be fixed or movable as desired. By using sensors, the support structure MT can 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 target portion C to be created for forming a device in an integrated circuit.

[0035] The pattern forming device MA can be a transmissive type (such as Figure 1Blithographic apparatus 100 ′) or reflective (as in Figure 1A 100). 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, as well as various hybrid mask types. Examples of programmable mirror arrays use 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 in the radiation beam B that is reflected by the matrix of small mirrors.

[0036] The term "projection system" PS may encompass any type of projection system suitable for the exposure radiation used or for other factors, such as the use of an immersion liquid on the substrate W or the use of a vacuum, including refractive, reflective, catadioptric, magnetic, electromagnetic, and electrostatic optical systems, or any combination thereof. Because other gases may absorb excessive radiation or electrons, a vacuum environment may be used for EUV or electron beam radiation. Thus, a vacuum environment can be maintained throughout the beam path using vacuum walls and a vacuum pump.

[0037] The 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 other substrate tables WT may be used for exposure while preparatory steps are being performed on one or more tables. 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 a portion of the substrate may be covered by a liquid having a relatively high refractive index (e.g., water) so as to fill the space between the projection system and the substrate. Immersion liquid may also be applied to other spaces in the lithographic apparatus, such as the space between the mask and the projection system. Immersion techniques are well known in the art for increasing the numerical aperture of projection systems. The term "immersion" as used herein does not imply that a structure, such as a substrate, is necessarily immersed in the liquid, but only that the liquid is located between the projection system and the substrate during exposure.

[0039] refer to Figure 1A and Figure 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 and 100' may be separate physical entities. In such a case, the source SO is not considered to form part of the lithographic apparatus 100 and 100', and the radiation beam B is provided by means of a beam delivery system BD ( Figure 1B The radiation is transferred from the source SO to the illuminator IL (in the embodiment of the present invention). 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 and 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 for adjusting the angular intensity distribution of the radiation beam ( Figure 1B In general, at least the outer radial extent and / or the 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. In addition, the illuminator IL may include various other components ( Figure 1B ), such as an integrator IN and a condenser CO. The illuminator IL can be used to condition the radiation beam B to have a desired uniformity and intensity distribution in its cross-section.

[0041] refer to Figure 1A , a radiation beam B is incident on a patterning device (e.g., a mask) MA, which is held on a support structure (e.g., a mask table) MT, and is patterned by the patterning device MA. In the lithographic apparatus 100, the radiation beam B is reflected from the patterning device (e.g., a mask) MA. After being reflected from the patterning 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 interferometry 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., a mask) MA relative to the path of the radiation beam B. Mask alignment marks M1, M2 and substrate alignment marks P1, P2 can be used to align the patterning device (e.g., a mask) MA and the substrate W.

[0042] refer to Figure 1B , 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 passing through mask MA, radiation beam B passes through projection system PS, which focuses the beam onto a target portion C of substrate W. The projection system has an illumination system pupil IPU at a pupil conjugate PPU. A portion of the radiation emerges from the intensity distribution at illumination system pupil IPU and passes through the mask pattern without being affected by diffraction at the mask pattern, producing an image of the intensity distribution at illumination system pupil IPU.

[0043] Projection system PS projects an image MP' of a mask pattern MP onto a photoresist layer coated on substrate W, where image MP' is formed by a diffraction beam resulting from the mask pattern MP caused by radiation from an intensity distribution. For example, mask pattern MP can include an array of lines and spaces. Diffraction of radiation at the array, other than the zeroth-order diffraction, produces a diffracted beam having a change in direction perpendicular to the lines. The undiffracted beam (i.e., the so-called zeroth-order diffraction beam) passes through the pattern without any change in propagation direction. The zeroth-order diffraction beam passes through an upper lens or upper lens group of projection system PS (located upstream of the pupil conjugate or conjugate pupil PPU of projection system PS) to reach pupil conjugate PPU. The portion of the intensity distribution in the plane of pupil conjugate PPU and associated with the zeroth-order diffraction beam is an image of the intensity distribution in illumination system pupil IPU of illumination system IL. The hole or aperture arrangement PD is for example arranged at or approximately at a plane of the projection system PS comprising the pupil conjugate PPU.

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

[0045] With the help of a second positioner PW and a position sensor IF (e.g. an interferometry device, a linear encoder, or a capacitive sensor), the substrate table WT can be accurately moved (e.g. in order to position a different target portion C in the path of the radiation beam B). Similarly, the substrate table WT can be accurately moved using a first positioner PM and another position sensor ( Figure 1B ) 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] Typically, 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 the short-stroke actuator only, or may be fixed. Mask alignment marks M1, M2 and substrate alignment marks P1, P2 may be used to align the mask MA with the substrate W. Although the substrate alignment marks (as shown) occupy dedicated target portions, these marks may be located in the spaces between target portions (called scribe line alignment marks). Similarly, in the case where more than one die is provided on the mask MA, the mask alignment marks may be located between the dies.

[0047] The mask table MT and patterning device MA can be located 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. Alternatively, an out-of-vacuum robot (IVR) can be used to perform various transport operations when the mask table MT and patterning device MA are outside the vacuum chamber, similar to the in-vacuum robot (IVR). Both the in-vacuum and out-of-vacuum robots need to be calibrated for smooth transfer of any payload (e.g., a mask) to the transfer station's fixed kinematic support.

[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 are held substantially stationary (i.e. a single static exposure) while the entire pattern imparted to the radiation beam B is projected at one time onto a target portion C. 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 (i.e. single dynamic exposure) as a pattern imparted to the radiation beam B is projected onto a target portion C. 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 is held substantially stationary, thereby 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 used, with 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 applicable to maskless lithography utilizing a programmable patterning device, such as a programmable mirror array.

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

[0053] In a further embodiment, the lithographic apparatus 100 includes an extreme ultraviolet (EUV) source configured to generate an EUV radiation beam for EUV lithography. Typically, 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 greater detail and includes a source collector apparatus SO, an illumination system IL, and a projection system PS. The source collector apparatus SO is constructed and arranged so that a vacuum environment can be maintained within an enclosure 20. The source collector apparatus SO includes a source chamber 11 and a collector chamber 12, and is configured to generate and transmit EUV radiation. EUV radiation can be generated by a gas or vapor (e.g., Xe gas, Li vapor, or Sn vapor), wherein an EUV radiation-emitting plasma 10, i.e., an EUV radiation-emitting plasma 10, is generated to emit radiation in the EUV range of the electromagnetic spectrum. The at least partially ionized EUV radiation-emitting plasma 10 can be generated, for example, by an electrical discharge or a laser beam. A partial pressure of, for example, 10 Pa of Xe, Li, Sn vapor, or any other suitable gas or vapor, may be required to effectively generate the radiation. In an embodiment, an excited tin (Sn) plasma is provided to generate the EUV radiation.

[0055] Radiation emitted by EUV radiation-emitting plasma 10 passes from source chamber 11 into collector chamber 12 via an optional gas barrier or contamination trap 30 (also referred to as a contamination barrier or fin trap in some cases) positioned in or behind an opening of source chamber 11. Contamination trap 30 may include a channel structure. Contamination trap 30 may also include a gas barrier or a combination of a gas barrier and a channel structure. Herein, contamination trap or contamination barrier 30 is further referred to as including at least a channel structure.

[0056] The collector chamber 12 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 51 and a downstream radiation collector side 52. Radiation passing through the collector CO may be reflected by a grating spectral filter 40 to be focused at a virtual source point IF. The virtual source point IF is often referred to as an intermediate focus, and the source collector apparatus is arranged such that the intermediate focus IF is positioned at or near the opening 19 of the enclosure 20. The virtual source point IF is an image of the radiation-emitting plasma 10. The grating spectral filter 240 is particularly useful for suppressing infrared (IR) radiation.

[0057] The radiation then passes through an illumination system IL, which may include a faceted field mirror arrangement 22 and a faceted pupil mirror arrangement 24, which are arranged to provide a desired angular distribution of the radiation beam 21 at the patterning device MA, and a desired uniformity of radiation intensity at the patterning device MA. When the radiation beam 21 reflects at the patterning device MA (held by the support structure MT), a patterned beam 26 is formed, and is imaged by the projection system PS via reflective elements 28, 29 onto a substrate W held by a wafer stage or substrate table WT.

[0058] Typically there may be more elements present in the illumination optics unit IL and projection system PS than shown. A grating spectral filter 40 may optionally be present depending on the type of lithographic apparatus. Furthermore, there may be more than Figure 2 The reflectors shown in FIG are more reflectors, for example compared to Figure 2 As shown in , there may be one to six additional reflective elements in projection system PS.

[0059] like Figure 2 The collector optics CO illustrated in FIG2 is depicted as a nested collector with grazing incidence reflectors 53, 54 and 55, which is only an example of a collector (or collector mirror). The grazing incidence reflectors 53, 54 and 55 are arranged axially symmetrically around the optical axis O, and this type of collector optics CO is preferably used in combination with a discharge produced plasma source (commonly referred to as a DPP source).

[0060] Exemplary Lithography Cell

[0061] Figure 3A lithography cell 300 is shown, which is sometimes also referred to as a lithocell or cluster. 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 that perform pre-exposure and post-exposure processes on the substrate. Conventionally, these devices 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 transport device or robot RO picks up substrates from input / output ports I / O1 and I / O2, moves substrates between different process equipment, and transfers substrates to a feed station LB of the lithography apparatus 100 or 100'. These devices, often collectively referred to as a track or coating and developing system, are under the control of a track or coating and developing system control unit TCU, which is itself controlled by a supervisory control system SCS, which also controls the lithography apparatus via a lithography control unit LACU. Thus, the different devices can be operated to maximize throughput and processing efficiency.

[0062] Exemplary Pre-Alignment System

[0063] Figure 4 A schematic diagram of a pre-alignment system 400 configured to pre-align a patterning device (e.g., a reticle) 402 is shown according to some embodiments of the present disclosure. In some embodiments, the pre-alignment system 400 may be a Figure 1A and Figure 1B In some embodiments, the pre-alignment system 400 includes at least two channels. In some embodiments, the pre-alignment system 400 includes a light source 404 and a multi-path sensing array 406, wherein the multi-path sensing array 406 provides at least two channels of the pre-alignment system 400.

[0064] Light source 404 is configured to illuminate reticle 402 with a radiation beam 414 of a predetermined wavelength used for reticle pre-alignment. In one embodiment, radiation beam 414 generated by light source 404 is in the near-infrared region between 650 nm and 1000 nm. In another embodiment, radiation beam 414 with a wavelength of 880 nm may be used. As will be appreciated by those skilled in the art, the wavelength of radiation beam 414 generated by light source 404 for reticle pre-alignment may be within other optical ranges, such as visible light between 390 nm and 700 nm. In one embodiment, light source 404 includes dual light sources 404 a and 404 b. In some embodiments, light source 404 may include a single light source or more than two light sources.

[0065] In some embodiments, pre-alignment system 400 is configured to direct radiation beam 414 at an oblique angle onto alignment mark 416 of reticle 402. Depending on the illumination or irradiance, alignment mark 416 can reflect light and produce diffracted beam 418, where an angle θ between diffracted beam 418 and radiation beam 414 corresponds to the diffraction angle.

[0066] In some embodiments, the mask 402 may be a reflective patterning device for extreme ultraviolet (EUV) lithography. Figure 1A and Figure 1B The mask MA is shown, and the alignment mark 416 can be as shown Figure 1A and Figure 1B Alignment marks M1 and M2 are shown.

[0067] In some embodiments, the pre-alignment system 400 is configured to direct the diffracted beam 418 to the multi-path sensing array 406 using a common objective lens set 420 and a beam splitter 412 .

[0068] The multi-path sensing array 406 may include one or more systems, such as an optical system, an imaging system, or a lens system, each of which includes a path, such as an optical path, an optical channel, a lens channel, etc. In one embodiment, the multi-path sensing array 406 includes an upper image lens system 408 and a lower image lens system 410, each corresponding to a channel of the pre-alignment system 400. In this example, the pre-alignment system 400 is also referred to as a bifurcated reflective pre-alignment system. In some embodiments, a beam splitter 412 is positioned between the common objective lens assembly 420 and the upper / lower image lens systems 408 / 410. In some embodiments, the beam splitter 412 may split a received diffracted beam 418 into two diffracted beamlets 418-1 and 418-2. The first diffracted beamlet may be directed to the upper image lens system 408, and the second diffracted beamlet may be directed to the lower image lens system 410. In some embodiments, the image lens system of the multi-path sensing array 406 may further include an independent lens assembly 424.

[0069] In some embodiments, the pre-alignment system 400 further includes a detector 422 and a controller ( Figure 4 Detector 422 may be a sensor or a sensor array. Each sensor may be a light detector (eg, a photodiode), an image sensor, etc. Controller 422 may generate a control signal for pre-aligning reticle 402 based on diffracted beam 418 .

[0070] In some embodiments, the pre-alignment system 400 utilizes Figure 4For example, the pre-alignment system 400 can measure the XY position and orientation of the reticle 402 using the dual channel configuration described in .

[0071] In some embodiments, upper image lens system 408 and lower image lens system 410 can be configured with different configurations to measure different properties of diffracted beam 418. For example, when illuminating reticle 402, incident light (e.g., radiation beam 414) can be diffracted (or, in some embodiments, scattered) by alignment mark 416 on reticle 402 and partially altered. Upon receiving diffracted beam 418, upper image lens system 408 and lower image lens system 410 can provide analysis and measurement of different optical properties of reticle 402. In one example, upper image lens system 408 can receive diffracted beamlet 418-1 and project an image of alignment mark 416 on reticle 402 onto detector 422-1. Similarly, lower image lens system 410 can receive diffracted beamlet 418-2 and project another image of alignment mark 416 onto detector 422-2. In some embodiments, lower image lens system 410 can generate an inverted image of reticle 402 to measure different alignment and / or positioning properties.

[0072] In some embodiments, detector 422 can be configured to measure the X-position and Y-position of reticle 402 by processing an image of alignment marks 416 on reticle 402. Alternatively, detector 422 can be a barcode reader configured to read an identification code of reticle 402. In some embodiments, upper image lens system 408 and lower image lens system 410 can be configured to perform other optical measurements and analyses on the image of reticle 402.

[0073] In some embodiments, the pre-alignment system 400 may further include a patterning device transfer apparatus (e.g., Figure 1B In-vacuum robots (IVRs) can be configured to minimize patterning device (e.g., reticle 402) exchange time, particle generation, and reduce contact forces or stresses from the chuck and / or patterning device. In-vacuum robots (IVRs) can also increase the efficiency of lithography (e.g., in Figure 1A and Figure 1B The overall throughput of the patterning device exchange process in the lithographic apparatus 100 or 100').

[0074] Telecentricity and Exemplary Pre-Alignment Systems

[0075] In some embodiments, the pre-alignment system 400 can be used to align the alignment of the two components at two separate levels or heights (L a and L b) to pre-align the mask 402 (see Figure 4 ). The vertical separation can be, for example, in the range of 1 mm to 100 mm. In some embodiments, telecentricity can be created for pre-alignment system 400, wherein the image magnification of reticle 402 can remain the same as the distance between reticle 402 and common objective lens group 420 changes. In other words, the patterning device (e.g., reticle 402) can be positioned at multiple working distances from common objective lens group 420, and pre-alignment system 400 can be configured so that the patterning device provides the same magnification at the detectors (e.g., detectors 422-1, 422-2, etc.) of each image lens system (e.g., upper / lower image lens systems 408 / 410) in at least one image lens system.

[0076] In some embodiments, the lens has an angular field of view that causes the magnification to decrease as the distance between the lens and the object increases. Therefore, when these lenses are used in a common objective lens set 420, the angular field of view may result in perspective errors. This can cause a decrease in accuracy or precision in measurements when the object (i.e., reticle 402) moves, as the detected image will change. A telecentric lens can eliminate perspective errors by having a constant, zero-angular field of view. A telecentric lens can provide the same field of view of an object at all distances from the lens. In the described example, the telecentric lens creates telecentricity in object space.

[0077] In some embodiments, a telecentric lens can also create telecentricity in image space, where the telecentric lens can be a compound lens with an exit pupil at a large distance. A chief ray passing through the center of the aperture stop can propagate parallel to the optical axis after the optical system.

[0078] Figure 5 An exemplary doubly telecentric optical system 500 is illustrated, in which both object space and image space are telecentric, according to some embodiments. Chief rays can be parallel to the optical axis in both object space and image space. In some embodiments of doubly telecentric optical system 500, the image of object 502 is insensitive to changes in magnification or the position of object 502 or image sensor 503.

[0079] In some embodiments, the bi-telecentric optical system 500 includes a first lens 526 and a second lens 528. Each of the first lens 526 and the second lens 528 may be a relay lens made of an optical lens or lens group that stretches and / or inverts the image of the object 502. In some embodiments, the focal points of the first lens 526 and the second lens 528 may be placed at the same location.

[0080] In some embodiments, the bi-telecentric optical system 500 can provide a magnified image of the object 502. For example, the lithographic apparatus 100 or 100' can be configured to provide a magnification value of the reticle MA in the range of 2 to 6 to achieve high-resolution patterning. In some embodiments, the ratio of the focal lengths of the first lens 526 and the second lens 528 corresponds to the magnification value of the image of the object 502. Therefore, in an optical system with high magnification, achieving bi-telecentricity in a compact design is challenging.

[0081] In some embodiments, the double telecentric optical system 500 may further include a condensing lens group 530, wherein the condensing lens group 530 has negative optical power and can provide a more compact design for the double telecentric optical system 500. For example, with the addition of the condensing lens group 530, the second lens 528 of the double telecentric optical system 500 may be closer to the first lens 526, such that Figure 5 However, in some embodiments, the overall size of the double telecentric optical system 500 may be limited by the magnification requirements and the size of the condenser lens assembly 530.

[0082] Return Reference Figure 4 , the pre-alignment system 400 can be configured to provide telecentricity in object space, where the image of the reticle 402 is insensitive to the magnification or position of the reticle 402. However, designing a pre-alignment system 400 with a compact size and telecentricity in image space can be challenging. Therefore, the pre-alignment system 400 can be semi-telecentric, and multiple iterations can be performed in compensator adjustment to achieve reliable performance.

[0083] Figure 6 Schematic diagram of a pre-alignment system 600 according to some embodiments of the present disclosure is shown. The pre-alignment system 600 can be similar to the pre-alignment system 400 and also have telecentricity in object space. However, the pre-alignment system 600 can include one or more telecentric converter lenses 640 configured to also provide telecentricity in the image space of the pre-alignment system 600. For example, Figure 6 As shown in , the chief ray in front of the detector 422 is parallel to the optical axis, or equivalently, the pupil is at infinity in image space.

[0084] In some embodiments, telecentric converter lens 640 can be a single optical lens located near the image plane (e.g., near detector 422) to convert diffracted beam 418-1 in image space into a telecentric beam. In other words, telecentric converter lens 640 can create telecentricity in the image space of the image lens systems (e.g., upper image lens system 408 and lower image lens system 410) used in pre-alignment system 600. By using a single optical lens, the optical design can be made compact and the changes from pre-alignment system 400 to pre-alignment system 600 can be minimized.

[0085] In some embodiments, the telecentric converter lens 640 can be made of materials such as glass, crystal, plastic, or any combination thereof. The curvature (e.g., three-dimensional profile) of the telecentric converter lens 640 can be designed based on numerical simulations (e.g., ray tracing). Thus, the three-dimensional (3D) profile or shape of the telecentric converter lens 640 can be custom designed to produce telecentricity for each diffracted beamlet (e.g., 418-1, 418-2, etc.) of the multi-path sensing array 406.

[0086] In some embodiments, numerical simulation using paraxial ray tracing can be used for a pre-aligned system 600 having an optical axis so that the 3D shape of the telecentric converter lens 640 can be obtained without considering surface tilt, surface type (such as splines), holograms, gradient indices, diffraction elements, etc.

[0087] In some embodiments, numerical simulations using true ray tracing can be performed to find the 3D profile of the telecentric converter lens 640. True rays (or exact rays) follow Snell's law. In some embodiments, the simulation program can evaluate the pre-alignment system 600 using two types of true rays (e.g., ordinary rays and reference rays). Ordinary rays can be rays that originate from a given point on the object surface (e.g., the surface of the alignment mark 416 on the patterning device 402) and trace through the pre-alignment system 600 in a predetermined direction. Reference rays can be rays that originate from a given point on the object surface and follow an initially unknown direction. The direction of the reference ray can be determined by requiring the ray to pass through some predetermined internal point in the pre-alignment system 600. In one example, a chief ray can be used as the reference ray, where the chief ray is emitted from the edge of the light field and passes through the center of the aperture stop.

[0088] In some embodiments, a telecentric converter lens 640 with a desired 3D profile can be created based on simulation results. The desired 3D profile of the telecentric converter lens 640 can be created using CNC cutting (e.g., hot air jet cutting, water jet cutting, laser cutting, or a combination thereof). Hot air jet cutting causes cracks in the lens material (e.g., glass) by introducing thermal stress into the material. Because the thermal stress is high in the area impacted by the jet, the crack propagates in the direction of the hot air jet. High-pressure water jets can also cut glass to the desired 3D profile. In some embodiments, both abrasive and non-abrasive water jet cutting techniques can be used for glass cutting. Non-abrasive techniques use only pure deionized high-pressure water, while abrasive cutting techniques can also use abrasive materials such as garnet, olivine, or silica in addition to the high-pressure water. In some embodiments, excimer laser ablation can be used to create the desired 3D profile of the telecentric converter lens 640. High-power lasers such as CO2, Nd:YAG, or argon lasers can be used. In some embodiments, short-pulse lasers in the nanosecond to femtosecond range can be implemented. In some embodiments, the laser may be in continuous wave (CW) mode.In some embodiments, creating the desired 3D profile of the telecentric converter lens 640 may also include grounding, mechanical polishing, molding, milling, or a combination thereof.

[0089] The embodiments may also be described using the following aspects:

[0090] 1. A pre-alignment system having at least two channels, comprising:

[0091] a common objective lens group configured to collect a diffracted beam from a patterning device, wherein the common objective lens group is further configured to create telecentricity in an object space of the pre-alignment system;

[0092] A multi-path sensing array comprising at least one image lens system, wherein the at least one image lens system comprises:

[0093] a telecentric converter lens configured to create telecentricity in image space of the pre-alignment system; and

[0094] a detector for each of the at least one image lens system, wherein the detector is configured to create a pre-alignment signal based on the diffracted beam.

[0095] 2. The pre-alignment system of aspect 1, wherein the telecentric converter lens comprises a single optical lens.

[0096] 3. The pre-alignment system of aspect 2, wherein the telecentric converter lens comprises glass, crystal or plastic.

[0097] 4. The pre-alignment system of aspect 2, wherein the telecentric converter lens is created by CNC cutting, the CNC cutting comprising hot air jet cutting, water jet cutting, and laser cutting.

[0098] 5. The pre-alignment system according to aspect 1, further comprising:

[0099] A light source is configured to illuminate the patterning device at an oblique angle.

[0100] 6. The pre-alignment system according to aspect 1, further comprising:

[0101] A beam splitter is configured to split the diffracted beam into two or more diffracted beamlets.

[0102] 7. A pre-alignment system according to aspect 6, wherein the beam splitter is located between the common objective lens group and the at least one image lens system.

[0103] 8. A pre-alignment system according to aspect 1, wherein the pattern forming device is located at multiple working distances from the common objective lens group, and the pre-alignment system is configured so that the pattern forming device provides the same magnification at the detector of each image lens system in the at least one image lens system.

[0104] 9. A lithographic apparatus comprising:

[0105] an illumination system configured to condition the radiation beam;

[0106] a support structure configured to support a patterning device;

[0107] a substrate stage configured to hold a substrate;

[0108] a projection system configured to project the pattern imparted to the radiation beam by the patterning device onto a target portion of the substrate; and

[0109] a first positioner and a second positioner configured to position the patterning device and the substrate, respectively, wherein the first positioner comprises:

[0110] A pre-alignment system having at least two channels, the pre-alignment system comprising:

[0111] a common objective lens group configured to collect a diffracted beam from the patterning device, wherein the common objective lens group is further configured to generate telecentricity in an object space of the pre-alignment system;

[0112] A multi-path sensing array comprising at least one image lens system, wherein the at least one image lens system comprises:

[0113] a telecentric converter lens configured to create telecentricity in image space of the pre-alignment system; and

[0114] a detector for each of the at least one image lens system, wherein the detector is configured to generate a pre-alignment signal based on the diffracted beam.

[0115] 10. The lithographic apparatus of clause 9, wherein the telecentric converter lens comprises a single optical lens.

[0116] 11. The lithographic apparatus of clause 10, wherein the telecentric converter lens comprises glass, crystal or plastic.

[0117] 12. The lithographic apparatus of clause 10, wherein the telecentric converter lens is created by CNC cutting, the CNC cutting comprising hot air jet cutting, water jet cutting, and laser cutting.

[0118] 13. The lithographic apparatus of clause 9, further comprising:

[0119] A light source is configured to illuminate the patterning device at an oblique angle.

[0120] 14. The lithographic apparatus of clause 9, further comprising:

[0121] A beam splitter is configured to split the diffracted beam into two or more diffracted beamlets.

[0122] 15. The lithographic apparatus of clause 14, wherein the beam splitter is located between the common objective lens group and the at least one image lens system.

[0123] 16. A lithographic apparatus according to aspect 9, wherein the pattern forming device is located at multiple working distances from the common objective lens group, and the pre-alignment system is configured to cause the pattern forming device to provide the same magnification at the detector of each image lens system in the at least one image lens system.

[0124] Although specific reference may be made herein to the use of lithographic equipment in IC manufacturing, it should be understood that the lithographic equipment described herein may have other applications, such as in the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, LCDs, thin film heads, etc. Those skilled in the art will understand that in the context of such alternative applications, any use of the term "substrate" or "target portion" herein may be considered synonymous with the more general term "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 tool, and / or a detection tool. Where applicable, the disclosure herein may be applied to these and other substrate processing tools. In addition, a substrate may be processed more than once, for example to form a multi-layer IC, so that the term "substrate" as used herein may also refer to a substrate that already includes multiple processed layers.

[0125] It should be understood that the phraseology or terminology herein is for the purpose of description rather than limitation, so that the phraseology or terminology of this specification will be interpreted by those skilled in the relevant art based on the teachings herein.

[0126] As used herein, the term "substrate" describes a material onto which a layer of material is added. In some embodiments, the substrate itself can be patterned, and the material added on top of the substrate can also be patterned, or can be left unpatterned.

[0127] Embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present invention may also be implemented as instructions stored on a machine-readable medium, which can 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 propagated signals; and the like. Furthermore, firmware, software, routines, and / or instructions may be described herein as performing specific actions. However, it should be understood that such descriptions are for convenience only and that such actions actually result from a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, and the like.

[0128] The accompanying examples are illustrative rather than limiting embodiments of the present disclosure. Other suitable modifications and adjustments to the various conditions and parameters normally encountered in the art (and which will be apparent to those skilled in the relevant art) will fall within the spirit and scope of the present disclosure.

[0129] Although specific reference may be made herein to the use of the apparatus and / or system according to the present invention in the manufacture of ICs, it should be clearly understood that such apparatus and / or system has many other possible applications. For example, it may be used to manufacture integrated optical systems, guidance and detection patterns for magnetic domain memories, LCD panels, thin film magnetic heads, etc. Those skilled in the art will understand that in the context of such alternative applications, any use of the terms "reticle," "wafer," or "die" herein should be considered to be replaceable with the more general terms "mask," "substrate," and "target," respectively.

[0130] While specific embodiments of the present 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.

[0131] 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, exemplary embodiments of the present invention as contemplated by the inventors, and thus, are not intended to limit the present invention and the appended claims in any way.

[0132] The present invention has been described above with the aid of functional building blocks that illustrate the implementation 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.

[0133] The foregoing description of the specific embodiments will sufficiently reveal the general nature of the invention so that others, by applying knowledge within the art, can readily modify and / or adapt these specific embodiments for various applications without undue experimentation and without departing from the general concepts of the invention. Therefore, based on the teaching and guidance presented herein, such modifications and adaptations are intended to fall within the meaning and range of equivalents of the disclosed embodiments.

[0134] 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. A pre-alignment system having at least two channels, comprising: a common objective lens group configured to collect a diffracted beam from a patterning device, wherein the common objective lens group is further configured to create telecentricity in an object space of the pre-alignment system; A multi-path sensing array comprising at least one image lens system, wherein the at least one image lens system comprises: a telecentric converter lens configured to create telecentricity in image space of the pre-alignment system; and a detector for each of the at least one image lens system, wherein the detector is configured to generate a pre-alignment signal based on the diffracted beam; Wherein the at least two channels provide analysis and measurement of different optical properties of the patterning device, and the three-dimensional profile or shape of the telecentric converter lens is customized for each channel.

2. The pre-alignment system according to claim 1, wherein: The telecentric converter lens includes a single optical lens.

3. The pre-alignment system according to claim 2, wherein: The telecentric converter lens comprises glass, crystal or plastic.

4. The pre-alignment system according to claim 2, wherein: The telecentric converter lens is manufactured by CNC cutting, which includes hot air jet cutting, water jet cutting and laser cutting.

5. The pre-alignment system according to claim 1 , further comprising: A light source is configured to illuminate the patterning device at an oblique angle.

6. The pre-alignment system according to claim 1 , further comprising: A beam splitter is configured to split the diffracted beam into two or more diffracted beamlets.

7. The pre-alignment system according to claim 6, wherein: The beam splitter is located between the common objective lens group and the at least one image lens system.

8. The pre-alignment system according to claim 1, wherein: The patterning device is located at a plurality of working distances from the common objective lens group, and the pre-alignment system is configured such that the patterning device provides the same magnification at a detector of each of the at least one image lens system.

9. A lithographic apparatus comprising: an illumination system configured to condition the radiation beam; a support structure configured to support a patterning device; a substrate stage configured to hold a substrate; a projection system configured to project the pattern imparted to the radiation beam by the patterning device onto a target portion of the substrate; as well as a first positioner and a second positioner, the first positioner and the second positioner being configured to position the patterning device and the substrate, respectively, wherein the first positioner comprises: A pre-alignment system having at least two channels, the pre-alignment system comprising: a common objective lens group configured to collect a diffracted beam from the patterning device, wherein the common objective lens group is further configured to generate telecentricity in an object space of the pre-alignment system; A multi-path sensing array comprising at least one image lens system, wherein the at least one image lens system comprises: a telecentric converter lens configured to create telecentricity in image space of the pre-alignment system; and a detector for each of the at least one image lens system, wherein the detector is configured to generate a pre-alignment signal based on the diffracted beam; Wherein the at least two channels provide analysis and measurement of different optical properties of the patterning device, and the three-dimensional profile or shape of the telecentric converter lens is customized for each channel.

10. The lithographic apparatus according to claim 9, wherein The telecentric converter lens includes a single optical lens.

11. The lithographic apparatus according to claim 10, wherein: The telecentric converter lens comprises glass, crystal or plastic.

12. The lithographic apparatus according to claim 10, wherein: The telecentric converter lens is manufactured by CNC cutting, which includes hot air jet cutting, water jet cutting and laser cutting.

13. The lithographic apparatus according to claim 9, further comprising: A light source is configured to illuminate the patterning device at an oblique angle.

14. The lithographic apparatus according to claim 9, further comprising: A beam splitter is configured to split the diffracted beam into two or more diffracted beamlets.

15. The lithographic apparatus of claim 14, wherein: The beam splitter is located between the common objective lens group and the at least one image lens system.

16. The lithographic apparatus according to claim 9, wherein: The patterning device is located at a plurality of working distances from the common objective lens group, and the pre-alignment system is configured such that the patterning device provides the same magnification at a detector of each of the at least one image lens system.

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