Method and system for generating lithographic process perceived pupil profiles

Abstract

A method and system for determining a pupil profile for imaging a pattern on a substrate in a lithographic process is disclosed. Data indicative of a relationship between a lithographic performance change and a source change throughout the pupil plane is obtained, based on which the first pupil profile is optimized to generate a second pupil profile. The second pupil profile is a discrete pupil profile corresponding to a desired free-form pupil profile that can be used to print a pattern on a substrate using a lithographic apparatus. An illumination system (e.g., a field facet mirror) may be configured based on the second pupil profile to print a pattern on the substrate.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to US application 63 / 454,022, filed March 22, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0003] This article describes a lithography apparatus or process, and more specifically a tool for optimizing the irradiation source and / or pattern forming apparatus / design layout used in the lithography apparatus or process. Background Technology

[0004] A lithography apparatus is a machine configured to apply a desired pattern onto a substrate. For example, lithography apparatus can be used to manufacture integrated circuits (ICs). A lithography apparatus can project a pattern (often referred to as a “design layout” or “design”) from a patterning apparatus (e.g., a mask) onto a layer of radiation-sensitive material (resist) disposed on a substrate (e.g., a wafer). This manufacturing process can be called a patterning process or a lithography process. For example, an IC chip in a smartphone can be as small as a human thumb and may contain more than 2 billion transistors. Manufacturing ICs is a complex and time-consuming process where circuit components reside in different layers and involve hundreds of individual steps. Even an error in one step can cause problems with the final IC and potentially lead to device failure. High process yields and high wafer throughput can be affected by the presence of defects.

[0005] The illumination source (“source”) of a lithography apparatus can be optimized, either in conjunction with the patterning apparatus or independently, in an effort to improve overall lithographic fidelity. Conventional techniques use glass disks called diffractive optical elements (DOEs) to shape the light from the source. The light from the source can be characterized using a pupil profile (e.g., an image representing the spatial intensity distribution at the pupil plane). For complex pupil profiles, these DOEs may have to be custom-designed and fabricated. Some types of sources can use programmable arrays of individually adjustable mirrors (e.g., field-faceted mirrors). The source can produce arbitrary pupil profiles in a short duration—thus eliminating the long cycle times associated with DOE design and fabrication.

[0006] Although the number of adjustable mirrors can be as large as several hundred, the adjustable mirrors are still spatially discrete. In some lithographic projection systems, each mirror can be configured to be in one of several (e.g., two to six) discrete states. Due to the discrete nature of the mirrors, the actual pupil profile produced using the array of mirrors is similar to the desired pupil profile, but can still deviate significantly from the desired pupil profile, which is typically a spatially continuous profile. The desired pupil profile can be obtained from source optimization (SO), source mask optimization (SMO), source mask lens optimization (SMLO), an empirical pupil profile, a pupil profile from another lithographic projection system, etc. In EUV sources, this deviation tends to be larger. If the discrete nature of the mirrors is taken into account when optimizing the source, the deviation can be reduced. However, traditional discrete optimization (e.g., branch and bound algorithms) is computationally expensive (the running time can increase exponentially with the number of mirrors). Some discrete pupil profile generators are geometry-based and do not take into account lithographic performance when generating the discrete pupil profile. More specifically, these methods do not distinguish between “more beneficial regions” (e.g., regions with lower lithographic performance cost) and “less beneficial regions” (e.g., regions with higher lithographic performance cost). Some other methods can take into account lithographic performance, but are computationally expensive (e.g., these methods can need to perform a simulation model that simulates the entire lithographic process every time a change is made to the pupil profile to determine whether the pupil profile is optimized). SUMMARY

[0007] In some aspects, the techniques described herein relate to a method for determining a pupil profile for imaging a pattern on a substrate in a lithographic process. The method includes obtaining a first pupil profile for printing a pattern on a substrate using a lithographic apparatus; obtaining data indicative of a relationship between variations in lithographic performance and variations in a source across a pupil plane; and discretizing the first pupil profile based on the data to generate a second pupil profile.

[0008] In some aspects, the techniques described herein relate to a method for determining a pupil profile for imaging a pattern on a substrate in a lithographic process. The method includes obtaining a first pupil profile for printing a pattern on a substrate using a lithographic apparatus; obtaining a lithographic performance based source optimization map indicative of a relationship between variations in lithographic performance and variations in a source across a pupil plane; and using the lithographic performance based source optimization map, generating a discrete pupil profile by iteratively optimizing the first pupil profile until a cost function is minimized.

[0009] In some aspects, the technology described herein relates to an apparatus for determining a pupil profile for imaging a pattern on a substrate in a lithographic process, the apparatus comprising: a memory storing a set of instructions; and a processor configured to execute the set of instructions to cause the apparatus to perform the method of any of the preceding aspects.

[0010] In some aspects, the technology described herein relates to a non-transitory computer readable medium having instructions recorded thereon, which when executed by a computer implement the method of any of the preceding aspects. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a schematic diagram of a lithographic projection apparatus according to an embodiment.

[0012] Figure 2 is a schematic diagram of another lithographic projection apparatus according to an embodiment.

[0013] Figure 3 is a detailed view of a lithographic projection apparatus according to an embodiment.

[0014] Figure 4 is a block diagram of a field facet mirror and a pupil facet mirror of a lithographic apparatus, consistent with various embodiments.

[0015] Figure 5 shows a flow for a lithographic process or patterning simulation method, consistent with various embodiments.

[0016] Figure 6 is a block diagram of a system for generating a source optimization guide (SOG) map, consistent with various embodiments.

[0017] Figure 7 is a block diagram of a system for generating discrete pupil profiles using a source optimization guide map, consistent with various embodiments.

[0018] Figure 8A and Figure 8B is a flow diagram of a method for generating discrete pupil profiles using a source optimization guide map, consistent with various embodiments.

[0019] Figure 9 is a block diagram of a computer system 100 that can aid in the implementation of the systems and methods disclosed herein. DETAILED DESCRIPTION

[0020] Embodiments of generating discrete pupil profiles using source optimization guidance (SOG) maps are disclosed. The source optimization guidance map indicates the relationship between lithographic performance variations and source variations across the pupil plane. In some embodiments, each value on the source optimization guidance map can indicate the effect of source intensity at a specific location on the pupil plane on lithographic performance (e.g., the performance of lithography / lithography processes in imaging patterns on a substrate). For example, the source optimization guidance map represents the gradient of source variations in a lithography apparatus. Increasing source intensity at locations on the pupil plane corresponding to larger positive values ​​in the source optimization guidance map increases lithographic performance costs (e.g., decreases lithography performance), while increasing source intensity at locations corresponding to larger negative values ​​in the source optimization guidance map may decrease lithographic performance costs (e.g., increases lithography performance). Therefore, the desired pupil can be determined by configuring the illumination system (e.g., a field-faceted mirror) to distribute source intensity to selected locations (specifically, locations on the pupil plane corresponding to larger negative values ​​in the source optimization guidance map).

[0021] In some embodiments, the discrete pupil profile generation process includes selecting a state for each of a plurality of field faceted mirrors (FFMs) in an illumination system, based on a source optimization guidance map. Each FFM is associated with a plurality of pupil faceted mirrors (PFMs), and selecting the state of the FFM includes selecting one of the plurality of pupil faceted mirrors that has a low negative value (representing low lithography performance cost) on, for example, the source optimization guidance map, setting the corresponding position on the pupil profile to a first value indicating the presence of source intensity, and setting other positions on the pupil profile corresponding to other pupil faceted mirrors associated with the FFM to a second value indicating the absence of source intensity. The pupil profile can be iteratively optimized by reducing the number of FFMs in each iteration until a cost function is minimized, which can be determined based on the source intensity values ​​in the updated pupil profile and the source optimization guidance map. The above-described method of generating discrete pupil profiles using a source optimization guidance map outperforms conventional discrete optimization techniques. For example, because it eliminates the need to execute a lithography simulation model that simulates the entire lithography process every time the pupil profile is changed, generating discrete pupil profiles using source optimization guidance maps consumes significantly fewer computational resources compared to conventional discrete optimization techniques. Therefore, this embodiment provides an improved discrete pupil profile generation process.

[0022] Figure 1 A lithography apparatus according to one or more embodiments is schematically illustrated. The lithography apparatus includes:

[0023] Irradiation system (irradiator) IL, the irradiation system being configured to modulate radiation beam B (e.g., UV radiation or DUV radiation).

[0024] A first object holder or support structure (e.g., a mask stage) MT is configured to hold a pattern forming apparatus (e.g., a mask) MA and is connected to a first positioner PM, which is configured to precisely position the pattern forming apparatus according to certain parameters.

[0025] A second object holder, such as a substrate holder or substrate stage (e.g., a wafer stage) WT, is configured to hold a substrate (e.g., a resist-coated wafer) W and is connected to a second positioner PW, which is configured to precisely position the substrate according to certain parameters; and

[0026] A projection system (e.g., a refractive projection lens system) PS, which is configured to project a pattern given by a radiation beam B by a pattern forming apparatus MA onto a target portion C (e.g., comprising one or more dies) of a substrate W.

[0027] An irradiation system (IL) may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof, for guiding, shaping, or controlling radiation.

[0028] The support structure holds the patterning apparatus in a manner dependent on the orientation of the patterning apparatus, the design of the lithography equipment, and other conditions, such as whether the patterning apparatus is held in a vacuum environment. The support structure can employ mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning apparatus. The support structure can be a frame or a stage, which may be fixed or movable as needed. The support structure ensures that the patterning apparatus is in a desired position, for example, relative to a projection system. Any use of the terms "mask" or "mask" herein may be considered synonymous with the more general term "patterning apparatus".

[0029] The term "patterning apparatus" as used herein should be broadly understood to refer to any apparatus capable of imparting a pattern to a radiation beam in the cross-section of the beam, thereby forming a pattern in a target portion of a substrate. It should be noted that, for example, if the pattern includes phase-shifting features or so-called auxiliary features, the pattern imparted to the radiation beam may not correspond precisely to the desired pattern on the target portion of the substrate. Typically, the pattern imparted to the radiation beam will correspond to a specific functional layer in a device formed on the target portion, such as an integrated circuit.

[0030] Pattern forming apparatuses can be transmissive or reflective. Examples of pattern forming apparatuses include masks, arrays of programmable mirrors, and programmable LCD panels. Masks are well known in photolithography and include mask types such as binary, alternating phase-shift, and attenuation phase-shift masks, as well as various hybrid mask types. An example of an array of programmable mirrors uses a matrix arrangement of small mirrors, each of which can be individually tilted to reflect the incident radiation beam in different directions. The tilted mirrors impart a pattern to the radiation beam reflected by the mirror matrix.

[0031] The term “projection system” as used herein should be interpreted broadly to encompass any type of projection system suitable for the exposure radiation used or for other factors such as immersion in liquids or vacuum, including refractive, reflective, reflective-refractive, magnetic, electromagnetic, and electrostatic optical systems, or any combination thereof. Any use of the term “projection lens” herein may be considered synonymous with the more general term “projection system.”

[0032] As described herein, the device is transmissive (e.g., employing a transmissive mask). Alternatively, the device may be reflective (e.g., employing a programmable mirror array as described above, or employing a reflective mask).

[0033] Photolithography equipment can be of the type having two substrate stages (dual stages) or more substrate stages (and / or two or more support structures). In such "multi-stage" machines, additional stage / support structures can be used in parallel, or one or more other stage / support structures can be used for exposure while preparation steps are performed on one or more stage / support structures.

[0034] refer to Figure 1 The irradiator IL receives the radiation beam from the radiation source SO. For example, when the source is an excimer laser, the source and the lithography apparatus can be separate entities. In such cases, the source is not considered part of the lithography apparatus, and the radiation beam is transmitted from the source SO to the irradiator IL by means of a beam delivery system BD, which includes, for example, suitable directional mirrors and / or beam expanders. In other cases, for example, when the source is a mercury lamp, the source can be an integral part of the lithography apparatus. The source SO and the irradiator IL, together with the beam delivery system BD, can be referred to as the radiation system when necessary.

[0035] The irradiator IL may include an adjuster AD for adjusting the angular intensity distribution of the radiation beam. Typically, at least the outer and / or inner radial ranges of the intensity distribution in the pupil plane of the irradiator (often referred to as σ_outer and σ_inner, respectively) can be adjusted. Additionally, the irradiator IL may include several other components, such as an integrator IN and a concentrator CO. The irradiator can be used to adjust the radiation beam to have a desired uniformity and intensity distribution in its cross-section.

[0036] A radiation beam B is incident on a patterning apparatus (e.g., a mask) MA held on a support structure (e.g., a mask stage) MT and patterned by the patterning apparatus. After passing through the patterning apparatus MA, the radiation beam B passes through a projection system PS, which focuses the beam onto a target portion C of the substrate W. The substrate stage WT can be precisely moved, for example, to position different target portions C within the path of the radiation beam B, by means of a second positioning device PW and a position sensor IF (e.g., an interferometric device, a linear encoder, or a capacitive sensor). Similarly, for example, after mechanical retrieval from a mask library or during scanning, a first positioning device PM and another position sensor (in…) Figure 1 (Another position sensor not explicitly shown) can be used to precisely position the pattern forming apparatus MA relative to the path of the radiation beam B. Typically, the movement of the support structure MT can be achieved by means of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning) forming the portion of the first positioner PM. Similarly, the movement of the substrate stage WT can be achieved by using a long-stroke module and a short-stroke module forming the portion of the second positioner PW. In the case of a stepper (relative to a scanner), the support structure MT may be connected only to the short-stroke actuator, or it may be fixed. The pattern forming apparatus MA and the substrate W can be aligned using pattern forming apparatus alignment marks M1, M2 and substrate alignment marks P1, P2. Although the illustrated substrate alignment marks occupy dedicated target portions, they can be located in the space between the target portions (these substrate alignment marks are referred to as scribing alignment marks). Similarly, in cases where more than one die is disposed on the pattern forming apparatus MA, the pattern forming apparatus alignment marks can be located between the dies.

[0037] The described device can be used in at least one of the following modes:

[0038] 1. In step mode, while keeping the support structure MT and substrate stage WT essentially stationary, the entire pattern imparting the radiation beam is projected onto the target portion C in a single exposure (i.e., a single static exposure). The substrate stage WT is then shifted along the X and / or Y directions, allowing exposure of different target portions C. In step mode, the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure.

[0039] 2. In the scanning mode, while the support structure MT and the substrate stage WT are scanned synchronously, a pattern imparted to the radiation beam is projected onto the target portion C (i.e., a single dynamic exposure). The velocity and direction of the substrate stage WT relative to the support structure MT can be determined by the (reduced) magnification and image inversion characteristics of the projection system PS. In the scanning mode, the maximum size of the exposure field limits the width of the target portion (along the non-scanning direction) in a single dynamic exposure, while the length of the scanning motion determines the height of the target portion (along the scanning direction).

[0040] 3. In another mode, the support structure MT used to maintain the programmable patterning apparatus is kept substantially stationary, and the pattern imparted by the radiation beam is projected onto the target portion C while the substrate stage WT is moved or scanned. In this mode, a pulsed radiation source is typically used, and the programmable patterning apparatus is updated as needed after each movement of the substrate stage WT or between consecutive radiation pulses during scanning. This mode of operation can be readily applied to maskless lithography utilizing a programmable patterning apparatus (e.g., an array of programmable mirrors of the type described above).

[0041] Alternatively, the above usage patterns or combinations and / or variations of completely different usage patterns may be adopted.

[0042] Figure 2 This is a schematic diagram of another photolithography projection apparatus (LPA) according to an embodiment. The LPA may include a source collector module SO, an irradiation system (irradiator) IL configured to modulate a radiation beam B (e.g., EUV radiation), a support structure MT, a substrate stage WT, and a projection system PS.

[0043] The support structure (e.g., a pattern forming apparatus stage) MT can be configured to support the pattern forming apparatus (e.g., a mask or mask plate) MA and connected to a first positioner PM configured to accurately position the pattern forming apparatus.

[0044] A substrate stage (e.g., a wafer stage) WT can be configured to hold a substrate (e.g., a wafer coated with resist) W and connected to a second locator PW configured to accurately position the substrate.

[0045] The projection system (e.g., a reflective projection system) PS can be configured to project a pattern, given by the pattern forming apparatus MA to the radiation beam B, onto a target portion C (e.g., comprising one or more dies) of the substrate W.

[0046] As described herein, the LPA can be reflective (e.g., employing a reflective patterning apparatus). It should be noted that because most materials are absorptive in the EUV wavelength range, the patterning apparatus can have a multilayer reflector, which may include, for example, a multilayer stack of molybdenum and silicon. In one example, the multilayer reflector has 40 pairs of molybdenum and silicon layers, where each layer is a quarter wavelength thick. Even smaller wavelengths can be produced using X-ray lithography. Since most materials are absorptive at both EUV and X-ray wavelengths, the patterned absorbent material thin sections on the morphology of the patterning apparatus (e.g., a TaN absorber on top of a multilayer reflector) define the locations where features will be printed (positive resist) or not printed (negative resist).

[0047] The irradiator IL can receive an extreme ultraviolet radiation beam from the source collector module SO. Methods for generating EUV radiation include, but are not limited to, converting a material into a plasma state having at least one element (e.g., xenon, lithium, or tin), wherein one or more emission lines are in the EUV range. In one such method, a plasma commonly referred to as laser-generated plasma (“LPP”) can be generated by irradiating a fuel (such as droplets, streams, or clusters of a material having a line-emitting element) with a laser beam. The source collector module SO may include a laser ( Figure 2 As part of an EUV radiation system (not shown), a laser beam is used to provide excitation of the fuel. The resulting plasma emits output radiation (e.g., EUV radiation), which is collected using a radiation collector located in a source collector module. For example, when a CO2 laser is used to provide the laser beam for fuel excitation, the laser and the source collector module can be separate entities.

[0048] In this case, the laser may not be considered part of the lithography apparatus, and the radiation beam can be delivered from the laser to the source collector module by means of a beam transmission system including, for example, suitable guiding mirrors and / or beam expanders. In other cases, such as when the source is a discharge-generated plasma EUV generator, commonly referred to as a DPP source, the source can be part of the source collector module.

[0049] An irradiator IL may include adjusters for adjusting the angular intensity distribution of the radiation beam. Typically, at least the outer and / or inner radial ranges of the intensity distribution in the pupil plane of the irradiator (often referred to as σ-outer and σ-inner, respectively) can be adjusted. Additionally, the irradiator IL may include various other components, such as faceted fields and pupil reflector devices. The irradiator can be used to adjust the radiation beam to have a desired uniformity and intensity distribution in its cross-section.

[0050] A radiation beam B can be incident on a pattern forming apparatus (e.g., a mask) MA held on a support structure (e.g., a pattern forming apparatus stage) MT and patterned by the pattern forming apparatus. After reflection from the pattern forming apparatus (e.g., the mask) MA, the radiation beam B passes through a projection system PS, which focuses the beam onto a target portion C of the substrate W. The substrate stage WT can be accurately moved, for example, to position different target portions C within the path of the radiation beam B, by means of a second locator PW and a position sensor PS2 (e.g., an interferometer, a linear encoder, or a capacitive sensor). Similarly, a first locator PM and another position sensor PS1 can be used to accurately position the pattern forming apparatus (e.g., the mask) MA relative to the path of the radiation beam B. The pattern forming apparatus (e.g., the mask) MA and the substrate W can be aligned using pattern forming apparatus alignment marks M1, M2 and substrate alignment marks P1, P2.

[0051] The described device LPA can be used in at least one of the following modes: step mode, scan mode, and stationary mode.

[0052] In step mode, the support structure (e.g., patterning apparatus stage) MT and substrate stage WT are kept substantially stationary (i.e., single static exposure) while the entire pattern applied to the radiation beam is projected onto the target portion C in one go. Then, the substrate stage WT is shifted along the X and / or Y directions so that different target portions C can be exposed.

[0053] In scanning mode, while projecting the pattern applied to the radiation beam onto the target portion C, the support structure (e.g., patterning apparatus stage) MT and the substrate stage WT are scanned simultaneously (i.e., single dynamic exposure). The speed and direction of the substrate stage WT relative to the support structure (e.g., patterning apparatus stage) MT can be determined by the magnification (reduction) and image inversion characteristics of the projection system PS.

[0054] In the static mode, the support structure (e.g., the patterning apparatus stage) MT is kept substantially stationary, thereby holding the programmable patterning apparatus in place, and the pattern imparted by the radiation beam is projected onto the target portion C as the substrate stage WT moves or scans. In this mode, a pulsed radiation source is typically used, and the programmable patterning apparatus is updated as needed after each movement of the substrate stage WT or between consecutive radiation pulses during scanning. This operating mode can be readily applied to maskless lithography utilizing a programmable patterning apparatus, such as an array of programmable mirrors as described above.

[0055] Figure 3This is a detailed view of a photolithography projection apparatus according to an embodiment. As shown, the LPA may include a source-collector module SO, an illumination system IL, and a projection system PS. The source-collector module SO is constructed and arranged such that a vacuum environment can be maintained within a closed structure 220 of the source-collector module SO. The EUV radiation-emitting plasma 210 may be formed by a discharge-generated plasma source. EUV radiation may be generated by a gas or vapor, such as Xe gas, Li vapor, or Sn vapor, wherein a very hot plasma 210 is generated to emit radiation in the EUV range of the electromagnetic spectrum. For example, the very hot plasma 210 is generated by a discharge that causes at least partial ionization of the plasma. For example, Xe, Li, Sn vapor, or any other suitable gas or vapor with a partial pressure of 10 Pa may be required to effectively generate radiation. In an embodiment, a plasma of excited tin (Sn) is provided to generate EUV radiation.

[0056] Radiation emitted by the hot plasma 210 is transferred from the source chamber 211 to the collector chamber 212 via an optional gas barrier or contaminant trap 230 (also referred to in some cases as a contaminant barrier or foil trap), which is 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 also include a gas barrier or a combination of a gas barrier and a channel structure. Contaminant traps or contaminant barriers 230 additionally indicated herein include at least a channel structure as known in the art.

[0057] 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 passing through the collector CO may be reflected by a grating spectral filter 240 to be focused onto a virtual source point IF along the optical axis indicated by the dashed line 'O'. The virtual source point IF is often referred to as the intermediate focus, and the source collector module is arranged such that the intermediate focus IF is located at or near the opening 221 in the enclosed structure 220. The virtual source point IF is an image of the radiative emission plasma 210.

[0058] Subsequently, radiation passes through an illumination system IL, which may include a faceted field mirror assembly 22 and a faceted pupil mirror assembly 24, arranged to provide a desired angular distribution of the radiation beam 21 at the patterning apparatus MA, and a desired uniformity of radiation intensity at the patterning apparatus MA. Upon reflection of the radiation beam 21 at the patterning apparatus MA, held by the support structure MT, a patterned beam 26 is formed, and the patterned beam 26 is imaged by the projection system PS through reflective elements 28 and 30 onto the substrate W held by the substrate stage WT.

[0059] Typically, more components than are shown can be present in the illumination optical unit IL and projection system PS. For example, the grating spectral filter 240 may be optionally present depending on the type of photolithography equipment. Furthermore, more mirrors than are shown in the figure, for example, compared to... Figure 3 As shown, one to six additional reflective elements may exist in the projection system PS.

[0060] like Figure 3 As shown, the collector optics CO is depicted as a nested collector with grazing incidence reflectors 253, 254, and 255, which is only an example of a collector (or collector mirror). The grazing incidence reflectors 253, 254, and 255 are configured to be axially symmetrical about the optical axis O, and this type of collector optics CO can be used in conjunction with a discharge-generated plasma source (commonly referred to as a DPP source).

[0061] Figure 4 This is a block diagram of the field-faceted mirror and the pupil-faceted mirror of a photolithography apparatus consistent with the various embodiments. In some embodiments, the field-faceted mirror (FFM) (such as field-faceted mirrors 401, 402, 403, and 404) and the pupil-faceted mirror (PFM) 410 are respectively similar to at least the reference reference. Figure 2 The described field-faceted mirror and pupil-faceted mirror, or respectively similar to Figure 3 The faceted field reflector device 22 and the faceted pupil reflector device 24 described herein. As mentioned above, at least refer to... Figure 2As described, the irradiator IL can adjust the angular intensity distribution of the radiation beam. In some embodiments, the irradiator can adjust the angular intensity distribution by using a field-faceted mirror and a pupil-faceted mirror. Furthermore, each field-faceted mirror can be associated with several pupil-faceted mirrors and can be configured (e.g., flipped) to direct radiation to one of those pupil-faceted mirrors. For example, field-faceted mirror 401 can be associated with pupil-faceted mirrors 421, 422, 423, and 424 and can be configured to direct radiation to one of pupil-faceted mirrors 421 to 424. Similarly, field-faceted mirror 403 can be associated with pupil-faceted mirrors 431, 432, 433, and 434 and can be configured to direct radiation to one of pupil-faceted mirrors 431 to 434. In other words, the pupil-faceted mirrors associated with the field-faceted mirrors are inherently mutually exclusive.

[0062] Each field facet mirror can be flipped into (or configured into) one of a plurality of states, and each state allows the field facet mirror to direct radiation to one of the pupil facet mirrors associated with the field facet mirror. For example, when field facet mirror 401 is flipped into a first state, field facet mirror 401 can direct radiation to pupil facet mirror 424; when field facet mirror 401 is flipped into a second state, field facet mirror 401 can direct radiation to pupil facet mirror 422, and so on.

[0063] Figure 5 An exemplary flowchart for modeling and / or simulating a patterning process (or lithography process) is shown below. As will be understood, the model may represent different patterning processes and need not include all the models described below. Source model 500 represents the optical characteristics of the illumination of the patterning apparatus (including radiation intensity distribution, bandwidth, and / or phase distribution). Source model 500 may represent the optical characteristics of the illumination, including but not limited to numerical aperture settings, illumination sigma (σ) settings, and any particular illumination shape (e.g., off-axis radiation shapes such as toroidal, quadrupole, dipole, etc.), where σ (or sigma) is the outer radial extent of the irradiator.

[0064] Projection optics model 510 represents the optical characteristics of the projection optics (including variations in radiation intensity distribution and / or phase distribution caused by the projection optics). Projection optics model 510 can represent the optical characteristics of the projection optics, including aberrations, distortion, one or more refractive indices, one or more physical dimensions, one or more physical dimensions, etc.

[0065] The patterning apparatus / design layout model module 520 captures how design features are laid out in a pattern within the patterning apparatus and may include a representation of the detailed physical properties of the patterning apparatus, such as those described in U.S. Patent No. 7,587,704, which is incorporated herein by reference in its entirety. In an embodiment, the patterning apparatus / design layout model module 520 represents the optical properties (including variations in radiation intensity distribution and / or phase distribution caused by a given design layout) of a design layout (e.g., a device design layout corresponding to features of an integrated circuit, memory, electronic device, etc.), which are representations of the arrangement of features on or formed by the patterning apparatus. Since the patterning apparatus used in a photolithography projection apparatus can be varied, it is desirable to separate the optical properties of the patterning apparatus from the optical properties of the rest of the photolithography projection apparatus, which includes at least an illuminator and projection optics. The purpose of simulation is typically to accurately predict, for example, edge placement and CD, which can then be compared to the device design. The device design is typically defined as a pre-OPC patterning apparatus layout and is provided in a standardized digital file format such as GDSII or OASIS.

[0066] A spatial image 530 can be simulated based on the source model 500, the projection optics model 510, and the pattern forming apparatus / design layout model module 520. The spatial image (AI) is the radiation intensity distribution at the substrate level. The optical properties of the photolithography projection equipment (e.g., the properties of the illumination, the pattern forming apparatus, and the projection optics) determine the spatial image.

[0067] A resist layer on a substrate is exposed to a spatial image, and this spatial image is transferred onto the resist layer as a potential "resist image" (RI). The resist image (RI) can be defined as the spatial distribution of the solubility of the resist in the resist layer. A resist image 550 can be simulated from the spatial image 530 using a resist model 540. The resist model can be used to calculate the resist image from the spatial image; examples of calculating the resist image from the spatial image can be found in U.S. Patent Application Publication No. 8,200,468, the disclosure of which is incorporated herein by reference in its entirety. Resist models typically describe the effects of chemical processes occurring during resist exposure, post-exposure baking (PEB), and development in order to predict, for example, the profile of resist features formed on the substrate, and therefore resist models are generally only related to this property of the resist layer (e.g., the effects of chemical processes occurring during exposure, PEB, and development). In the embodiments, the optical properties of the resist layer (e.g., refractive index, film thickness, propagation, and polarization effects) can be captured as part of the projection optics model 510.

[0068] Therefore, the connection between the optical model and the resist model is typically the simulated spatial image intensity within the resist layer, which is caused by the projection of radiation onto the substrate, refraction at the resist interface, and multiple reflections within the resist film stack. The radiation intensity distribution (spatial image intensity) is transformed into a potential "resist image" by absorbing incident energy, which is further modified by the diffusion process and various loading effects. For full-chip applications, a sufficiently fast and efficient simulation method approximates the true three-dimensional intensity distribution within the resist stack through a two-dimensional spatial (and resist) image.

[0069] In this embodiment, the resist image can be used as input to the post-pattern transfer process model module 560. The post-pattern transfer process model module 560 defines the performance of one or more post-resist development processes (e.g., etching, development, etc.).

[0070] Simulation of the patterning or photolithography process can, for example, predict contours, camber, edge placement (e.g., edge placement error) in the resist and / or etched image. Therefore, the aim of the simulation is to accurately predict, for example, the edge placement of the printed pattern, and / or the spatial image intensity slope, and / or camber. These values ​​can be compared to the expected design to, for example, correct the patterning process, identify the locations of predicted defects, etc. The expected design is typically defined as a pre-OPC design layout, which can be provided in a standardized digital file format such as GDSII or OASIS or other file formats.

[0071] Therefore, the model formulas describe most (if not all) of the physical and chemical processes involved in the entire process, and each model parameter ideally corresponds to a different physical or chemical effect. Thus, the model formulas set an upper limit on the effectiveness of the model in simulating the entire manufacturing process.

[0072] The following paragraphs describe the generation of discrete pupil profiles using source optimization guidance (SOG) maps according to embodiments of the present disclosure. Discrete pupil profiles can be used to configure the sources of a lithography apparatus to produce a desired pupil. The pupil profile (or pupil) describes the spatial intensity distribution at a pupil plane, which is an imaginary plane formed by a pupil faceted mirror in an illumination system, at or adjacent to the pupil faceted mirror. In some embodiments, the pupil profile can be represented using an image. Discrete pupil profiles can indicate the presence or absence of source intensity at specific locations on the pupil plane.

[0073] Figure 6This is a block diagram of a system 600 for generating exemplary source optimization guidance maps, consistent with various embodiments. A source optimization guidance map (or a lithography performance-based source optimization map) indicates the relationship between lithography performance variations and source variations across the pupil plane. In some embodiments, each value on the source optimization guidance map 604 indicates the effect of a source intensity variation at a specific location on the pupil plane on lithography performance (e.g., the performance of the lithography process in imaging a pattern onto a substrate). For example, the source optimization guidance map 604 is a graph of the gradients of source variables of a lithography apparatus. Figure 623 illustrates exemplary values ​​associated with various locations in the source optimization guidance map 604. In some embodiments, increasing the source intensity at locations on the pupil plane corresponding to larger positive values ​​in the source optimization guidance map 604 increases lithography performance costs (e.g., decreases lithography performance), while increasing the source intensity at locations corresponding to larger negative values ​​in the source optimization guidance map 604 decreases lithography performance costs (e.g., increases lithography performance). For example, increasing the source intensity in the first region 621 of the source optimization guide map 604 can result in better lithographic performance (e.g., a more beneficial region) compared to increasing the source intensity in the second region 622 (e.g., a less beneficial region) of the source optimization guide map 604. Therefore, by configuring field faceted mirrors to distribute the source intensity to pupil faceted mirrors corresponding to selected locations (e.g., locations on the pupil plane corresponding to larger negative values ​​on the source optimization guide map 604), the desired pupil profile (e.g., pupil profile 602) can be determined.

[0074] This disclosure is not limited to any particular method for generating a source optimization guidance map. In some embodiments, the source optimization guidance map 604 can be obtained from a source mask optimization (SMO) process. In some embodiments, the source mask optimization process determines the optimal source and / or mask variables for imaging a pattern onto a substrate. A source and pattern forming apparatus (design layout) optimization method and system that allows simultaneous optimization of the source and pattern forming apparatus using a cost function without constraints is described in commonly assigned international patent application No. PCT / US2009 / 065359, filed November 20, 2009, entitled "Fast Freeform Source and Mask Co-Optimization Method," which is incorporated herein by reference in its entirety. Another source and mask optimization method and system for optimizing a source by adjusting the pixels of a source is described in commonly assigned U.S. Patent Application No. 12 / 813456, filed June 10, 2010, entitled U.S. Patent No. 8,786,824, entitled “Source-Mask Optimization in Lithographic Apparatus”, which is incorporated herein by reference in its entirety.

[0075] The source mask optimization process can optimize source and / or mask variables based on various parameters, such as edge placement error (EPE), wavefront aberration, and critical size (CD). Figure 6 In the example, source mask optimization unit 605 optimizes source and mask variables 606 based on cost function 610, which is determined based on one or more parameters (such as EPE 608). Source and mask variables 606 are input to lithography process unit 625, which, when executed, simulates the lithography process (e.g., at least with reference to...). Figure 5The described process involves calculating various parameters, including EPE 608, at each iteration. Subsequently, the cost function 610 and its gradient (ds / dEPE) relative to EPE 608 are calculated and propagated back to the lithography process unit 625. The lithography process unit 625 transforms the gradient (ds / dEPE) relative to EPE 608 into a gradient (e.g., source gradient (ds / dv)) 609 relative to the source and / or mask variables, which, along with the cost function 610, is sent back to the source mask optimization unit 605 to complete the iteration loop. The source mask optimization unit 605 can continue iterating the optimization of the source and / or mask variables 606 until a condition is met (e.g., minimizing the cost function 610). When this condition is met, the source and / or mask variables 606 are considered optimized, and the source mask optimization process is considered to be in a good convergence phase. For example, pupil profile 602 shows an optimized continuous source intensity distribution on the pupil plane, which can be discretized to produce a discrete pupil profile, as described at least with reference to the following paragraphs. A source optimization guidance map 604 can be generated based on the source gradient (ds / dv) 609 values ​​obtained from a well-converged state of the source mask optimization process. According to embodiments of this disclosure, the source optimization guidance map 604 is used to guide pupil generation, such as a pupil discretization process.

[0076] Figure 7 This is a block diagram of an exemplary system 700 for generating discrete pupil profiles using a source optimization guidance map, consistent with the various embodiments. Figure 8A and Figure 8B These are flowcharts of exemplary methods 800 and 850 for generating discrete pupil profiles using source optimization guidance maps, consistent with the various embodiments.

[0077] At process P810, component 725 of the source optimization guidance map can obtain a first pupil profile. For example, component 725 of the source optimization guidance map can obtain a first pupil profile 705, which can be a discrete pupil profile. In some embodiments, the first pupil profile is a randomly discrete pupil profile, or it is generated from a continuous pupil produced by source mask optimization using any other suitable method.

[0078] At process P820, the source optimization guide map component 725 can obtain data indicating the relationship between lithographic performance variations and source variations throughout the pupil plane. For example, the source optimization guide map component 725 can obtain a source optimization guide map 604 (e.g., as at least referenced). Figure 6 As described, each value on the source optimization guidance diagram 604 indicates the effect of source intensity variation at a specific location on the pupil plane on lithography performance.

[0079] At process P830, the pupil profile generation component 750 discretizes the first pupil profile based on the source optimization guidance map 604 to generate a second pupil profile 760. The second pupil profile 760 may be a discrete pupil profile corresponding to a desired pupil profile for imaging a pattern onto a substrate (e.g., a freeform pupil profile 602 representing a continuous source intensity distribution on the pupil pattern). The second pupil profile 760 may indicate the presence or absence of source intensity at a specific location on the pupil plane. In some embodiments, a first value may be used to indicate the presence of source intensity, and a second value may be used to indicate the absence of source intensity. In some embodiments, the pupil profile generation component 750 may generate the second pupil profile 760 by iteratively optimizing the first pupil profile 705 based on the source optimization guidance map 604 until a specific condition is met. In some embodiments, a cost function determined based on the source intensity in the first pupil profile 705 and the value of the source optimization guidance map is minimized. In some embodiments, generating the second pupil profile 760 may include determining the state of the field-faceted mirror based on the source optimization guidance map 604, as at least with reference to the following... Figure 8B The process described in the text.

[0080] In some embodiments, Figure 8B Method 850 can be used as Figure 8A This is performed as part of process P830. The source optimization guide map component 725 generates a resampled source optimization guide map 710 by interpolating the image representation of the pupil faceted mirror's mesh on the source optimization guide map 604.

[0081] At process P850, the pupil contour generation component 750 can determine the state 712 of each of the multiple field-faceted mirrors based on the source optimization guidance map 604. For example, the pupil contour generation component 750 can determine the state 712 of a particular field-faceted mirror based on one of the pupil-faceted mirrors associated with the field-faceted mirror that has a minimum or maximum negative value on the source optimization guidance map 604. For example, in Figure 7In the example, the first field-faceted mirror 401 is associated with four pupil-faceted mirrors 421 to 424, and because pupil-faceted mirror 422 is located in the maximum negative value on the source optimization guidance map 604, the pupil contour generation component 750 can select pupil-faceted mirror 422. Therefore, the pupil contour generation component 750 can determine the state 712 of the first field-faceted mirror 401 based on the selected pupil-faceted mirror. For example, if the first field-faceted mirror 401 has four states (e.g., states "1" to "4"), and if state "2" corresponds to the position of the first field-faceted mirror 401 that directs radiation to the pupil-faceted mirror 422, then the pupil contour generation component 750 can determine the value of state 712 as "2".

[0082] At process P860, the pupil profile generation component 750 updates the first pupil profile 705 based on the determined state of each of the plurality of field-faceted mirrors. In some embodiments, updating the first pupil profile 705 based on the state 712 of the first field-faceted mirror 401 includes setting the position on the first pupil profile 705 corresponding to the position of the pupil faceted mirror associated with the determined state 712 of the first field-faceted mirror 401 to a first value indicating the presence of source intensity, and setting the position on the first pupil profile 705 corresponding to the position of the pupil faceted mirror associated with other states of the first field-faceted mirror 401 to a second value indicating the absence of source intensity.

[0083] At determination process P870, the pupil profile generation component 750 determines whether specific conditions for optimizing the first pupil profile 705 are met. In some embodiments, a cost function 752 may be calculated based on the source optimization guidance map values ​​and source intensity values ​​in the first pupil profile 705. In some embodiments, the cost function 752 may be the product of the intensity value at each selected location in the first pupil profile and the value of the source optimization guidance map 604 at the selected location. For example, the cost function may be expressed as:

[0084] (Equation 1)

[0085] in, It is the source intensity at position i in the first pupil contour 705, and It is the source optimization guidance map value at the same location in the source optimization guidance map 604. In some embodiments, when the cost function is minimized, specific conditions for optimizing the first pupil profile 705 are satisfied.

[0086] Based on the determination that the cost function 752 has not been minimized, at process P880, the pupil profile generation component 750 reduces the number of field-faceted mirrors (e.g., the number used in process P850), and method 850 continues to process P850 to further determine the state of the field-faceted mirrors. Method 850 continues until the cost function 752 is reduced (e.g., minimized), thereby reducing the number of field-faceted mirrors and further optimizing the first pupil profile 705 in each iteration (e.g., updating based on the state of the field-faceted mirrors).

[0087] Based on the determination that the cost function 752 is minimized, at process P870, method 850 returns to process P830 of method 800, where pupil contour generation component 750 outputs an updated first pupil contour 705 as the second pupil contour 760.

[0088] In some embodiments, the pupil contour generation component 750 may also generate state information of the field-faceted mirrors based on the second pupil contour. For example, the state information may include a determined state of each field-faceted mirror in the illumination system. The state information can be used to configure a photolithography apparatus to print patterns on a substrate. For example, the state information may be input to the photolithography apparatus to cause the apparatus to flip the field-faceted mirrors to their respective states based on the state information. A patterning process can be performed by the photolithography apparatus to print patterns corresponding to a target layout on the substrate.

[0089] The method described above, which uses a source optimization guidance map to generate discrete pupil profiles, outperforms conventional discrete optimization techniques. For example, compared to conventional discrete optimization techniques, it eliminates the need to execute a lithography simulation model that simulates the entire lithography process every time the pupil profile is changed (e.g., at least with reference to...). Figure 5 As required by the process described, using source optimization guidance diagram 604 to generate discrete pupil profiles (e.g., second pupil profile 760) consumes significantly fewer computational resources.

[0090] Figure 9This is a block diagram illustrating a computer system 100 that can assist in implementing the systems and methods disclosed herein. The computer system 100 includes a bus 102 or other communication mechanism for communicating information, and a processor 104 (or multiple processors 104 and 105) coupled to the bus 102 for processing information. The computer system 100 also includes a main memory 106, such as random access memory (RAM) or other dynamic storage device, coupled to the bus 102 for storing instructions and information to be executed by the processor 104. The main memory 106 may also be used to store temporary variables or other intermediate information during the execution of instructions to be executed by the processor 104. The computer system 100 also includes a read-only memory (ROM) 108 or other static storage device coupled to the bus 102 for storing static information and instructions for the processor 104. A storage device 110, such as a magnetic disk or optical disk, is provided and coupled to the bus 102 for storing information and instructions.

[0091] Computer system 100 can be coupled via bus 102 to a display 112 for displaying information to a computer user, such as a cathode ray tube (CRT), flat panel display, or touch panel display. Input device 114, including alphanumeric keys and other keys, is coupled to bus 102 for communicating information and command selections to processor 104. Another type of user input device is a cursor controller 106, such as a mouse, trackball, or cursor direction keys, for communicating directional information and command selections to processor 104 and for controlling cursor movement on display 112. Such input devices typically have two degrees of freedom on two axes (i.e., a first axis (e.g., x) and a second axis (e.g., y)), which allow the device to specify its position in a plane. Touch panel (screen) displays can also be used as input devices.

[0092] According to one embodiment, a portion of an optimized process may be performed by computer system 100 in response to processor 104 executing one or more sequences of one or more instructions contained in main memory 106. These instructions may be read into main memory 106 from another computer-readable medium, such as storage device 110. Execution of the instruction sequences contained in main memory 106 causes processor 104 to perform the process steps described herein. One or more processors arranged in a multiprocessor configuration may also be employed to execute the instruction sequences contained in main memory 106. In alternative embodiments, a hard-wired circuit system may be used instead of or in combination with software instructions. Therefore, the description herein is not limited to any particular combination of hardware circuitry and software.

[0093] As used herein, the term "computer-readable medium" refers to any medium that participates in providing instructions to processor 104 for execution. Such media can take many forms, including but not limited to non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical discs or magnetic disks, such as storage device 110. Volatile media include dynamic memory, such as main memory 106. Transmission media include coaxial cables, copper wires, and optical fibers, including wires containing bus 102. Transmission media can also take the form of sound waves or light waves, such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media, for example, can include floppy disks, floppy disks, hard disks, magnetic tapes, any other magnetic media, CD-ROMs, DVDs, any other optical media, punched cards, paper tapes, any other physical media with a perforated pattern, RAM, PROMs and EPROMs, FLASH-EPROMs, any other memory chips or cartridges, carrier waves as described below, or any other medium from which a computer can read.

[0094] Various forms of computer-readable media can be included to carry one or more sequences of instructions to processor 104 for execution. For example, the instructions may initially be carried on the disk of a remote computer. The remote computer may load the instructions into its dynamic memory and transmit the instructions over a telephone line using a modem. A modem local to computer system 100 may receive data over the telephone line and convert the data into an infrared signal using an infrared transmitter. An infrared detector coupled to bus 102 may receive the data carried in the infrared signal and place the data on bus 102. Bus 102 carries the data to main memory 106, from which processor 104 retrieves and executes instructions. Instructions received by main memory 106 may optionally be stored on storage device 110 before or after execution by processor 104.

[0095] Computer system 100 also preferably includes a communication interface 118 coupled to bus 102. Communication interface 118 provides bidirectional data communication coupled to network link 120 connected to local area network 122. For example, communication interface 118 may be an Integrated Services Digital Network (ISDN) card or modem to provide data communication connectivity to a corresponding type of telephone line. As another example, communication interface 118 may be a local area network (LAN) card to provide data communication connectivity to a compatible LAN. A wireless link may also be implemented. In any such implementation, communication interface 118 transmits and receives electrical, electromagnetic, or optical signals carrying digital data streams representing various types of information.

[0096] Network link 120 typically provides data communication to other data devices via one or more networks. For example, network link 120 may provide connectivity to host computer 124 or data devices operated by Internet Service Provider (ISP) 126 via local area network 122. ISP 126, in turn, provides data communication services via a global packet data communication network now commonly referred to as the "Internet" 128. Both local area network 122 and Internet 128 use electrical, electromagnetic, or optical signals to carry digital data streams. Signals passing through various networks and signals on network link 120 and through communication interface 118 are exemplary forms of carrier waves that carry digital data to and from computer system 100.

[0097] Computer system 100 can send messages and receive data including program code via networks(s), network link 120, and communication interface 118. In the example of the Internet, server 130 can transmit requested code for an application via the Internet 128, ISP 126, local area network 122, and communication interface 118. For example, such a downloaded application can provide illumination optimization for the embodiment. The received code can be executed by processor 104 upon receipt and / or stored in storage device 110 or other non-volatile storage device for later execution. In this way, computer system 100 can obtain application code in carrier form.

[0098] While the concepts disclosed herein can be used for imaging on substrates such as silicon wafers, it should be understood that the disclosed concepts can be used with any type of lithography imaging system, for example, a lithography imaging system for imaging on substrates other than silicon wafers.

[0099] As used herein, the terms “optimized” and “optimization” refer to or indicate adjustments to patterning apparatus (e.g., photolithography equipment), patterning processes, etc., such that the results and / or processes have more desired characteristics, such as higher accuracy of the projection of the designed pattern onto the substrate, a larger process window, etc. Therefore, as used herein, the terms “optimized” and “optimization” refer to or indicate a process of identifying one or more values ​​of one or more parameters that, compared to an initial set of one or more values ​​of one or more parameters, provide an improvement (e.g., local optimum) on at least one relevant metric. “Optimal” and other related terms should be interpreted accordingly. In embodiments, optimization steps may be applied iteratively to provide further improvements on one or more metrics.

[0100] Various aspects of the present invention can be implemented in any convenient form. For example, embodiments can be implemented by one or more suitable computer programs that can be carried on a suitable carrier medium, which can be a tangible carrier medium (e.g., a disk) or an intangible carrier medium (e.g., a communication signal). Embodiments of the present invention can be implemented using suitable devices, which can specifically take the form of a programmable computer running a computer program arranged to implement the methods described herein. Therefore, embodiments of the present disclosure can be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present disclosure can also be implemented as instructions stored on a machine-readable medium that can be read and executed by one or more processors. A machine-readable medium can include any mechanism for storing or transmitting information in a machine-readable (e.g., computing device) form. For example, a machine-readable medium can include read-only memory (ROM); random access memory (RAM); disk storage media; optical storage media; flash memory devices; electrical, optical, acoustic, or other forms of propagation signals (e.g., carrier waves, infrared signals, digital signals, etc.). Furthermore, firmware, software, routines, and instructions can be described herein as performing certain actions. However, it should be understood that such a description is merely for convenience, and such actions are actually produced by a computing device, processor, controller, or other device that executes firmware, software, routines, instructions, etc.

[0101] Embodiments of this disclosure can be further described in the following ways.

[0102] 1. A method for determining a pupil profile for imaging a pattern onto a substrate during photolithography, the method comprising:

[0103] Obtain a first pupil profile for printing a pattern onto a substrate using photolithography equipment;

[0104] Obtain data indicating the relationship between changes in lithographic properties across the pupil plane and source variations; and

[0105] The first pupil contour is optimized based on the data to generate the second pupil contour.

[0106] 2. The method according to aspect 1, wherein the first pupil profile is a discrete pupil profile.

[0107] 3. The method according to aspect 1, wherein the data indicates a graph of the gradient of the source variables of the lithography apparatus, wherein each value on the graph indicates the effect of the source intensity variation at a specific location on the pupil plane on the lithography performance.

[0108] 4. The method according to aspect 3, wherein the graph is obtained from a source mask optimization (SMO) process.

[0109] 5. The method according to aspect 3, wherein the graph is obtained by:

[0110] Perform a source mask optimization process configured to determine a pupil profile representing a continuous source intensity distribution on the pupil plane; and

[0111] The graph is generated based on the source intensity gradient values ​​determined during the source mask optimization process.

[0112] 6. The method according to aspect 5, wherein the source mask optimization process is configured to optimize the pupil profile based on edge placement error.

[0113] 7. The method according to aspect 3, wherein the discretization includes iteratively optimizing the first pupil profile based on the graph to generate the second pupil profile.

[0114] 8. The method according to aspect 7, wherein the iterative optimization of the cost function is based on the combination of the graph and the first pupil profile.

[0115] 9. The method according to aspect 8, wherein the cost function is the product of the intensity value at each selected location in the first pupil profile and the value of the graph at the selected location.

[0116] 10. The method according to aspect 7, wherein each iteration includes:

[0117] For each of the multiple field-faceted mirrors in a specific number of field-faceted mirrors of the lithography apparatus, the state of the first field-faceted mirror is determined based on the values ​​in the graph;

[0118] Update the first pupil profile based on the state of the first faceted mirror; and

[0119] Based on the stated state, determine whether the cost function is reduced.

[0120] 11. The method according to aspect 10, further comprising:

[0121] In response to determining that the cost function has not been minimized, the specific number of the field-faceted reflectors is reduced.

[0122] 12. The method according to aspect 10, wherein updating the first pupil profile based on the state of the first field-faceted mirror comprises:

[0123] The position of the first pupil faceted mirror corresponding to the minimum value on the resampled image is obtained from the resampled image, wherein the first pupil faceted mirror is one of a set of pupil faceted mirrors associated with the first field faceted mirror; and

[0124] The first pupil contour is updated by setting the first position on the first pupil profile corresponding to the first pupil faceted mirror to a first value, and setting the positions of the remaining pupil faceted mirrors associated with the first pupil faceted mirror to a second value.

[0125] 13. The method according to aspect 12, wherein the first value indicates the presence of source strength, and the second value indicates the absence of the source strength.

[0126] 14. The method according to aspect 12, wherein the resampled image is generated by interpolating an image representation of the mesh of the pupil faceted mirror in the pupil plane.

[0127] 15. The method according to aspect 1 further includes:

[0128] The second pupil profile is used to generate state information, wherein the state information indicates the state of the corresponding field-faceted mirror for printing a pattern on a substrate for each of a plurality of field-faceted mirrors.

[0129] 16. The method according to aspect 15 further includes:

[0130] The status information is input into the photolithography device; and

[0131] The state of the field-faceted reflector is adjusted based on the state information.

[0132] 17. The method according to aspect 16 further includes:

[0133] A patterning process is performed via the photolithography equipment to print a pattern corresponding to the target layout onto the substrate.

[0134] 18. A method for determining a pupil profile for imaging a pattern onto a substrate during photolithography, the method comprising:

[0135] Obtain a first pupil profile for printing a pattern onto a substrate using photolithography equipment;

[0136] Obtain a source optimization map based on lithography performance, indicating the relationship between lithography performance variations and source variations throughout the pupil plane; and

[0137] Using the source optimization map based on lithography performance, a second pupil profile is generated by iteratively optimizing the first pupil profile until the cost function is minimized.

[0138] 19. The method according to aspect 18, wherein the source optimization map based on lithography performance is a graph of the gradients of the source variables of the lithography apparatus, wherein each value on the graph indicates the effect of the source intensity variation at a specific location on the pupil plane on the lithography performance.

[0139] 20. The method according to aspect 18, wherein the first pupil profile is a discrete pupil profile.

[0140] 21. The method according to aspect 18, wherein generating the second pupil profile comprises: iteratively optimizing the first pupil profile based on the source optimization map based on lithography performance.

[0141] 22. The method according to aspect 21, wherein the iterative optimization is based on a cost function of the combination of the source optimization map based on lithography performance and the first pupil profile.

[0142] 23. The method according to aspect 22, wherein the cost function is the product of the intensity value at each selected location in the first pupil profile and the value of the source optimization map based on lithographic performance at the selected location.

[0143] 24. The method according to aspect 21, wherein each iteration includes:

[0144] For each of the multiple field-faceted mirrors of a specific number of lithography apparatus, the state of the first field-faceted mirror is determined based on the value on the source optimization map based on lithography performance;

[0145] Update the first pupil profile based on the state of the first faceted mirror; and

[0146] Based on the stated state, determine whether the cost function is reduced.

[0147] 25. The method according to aspect 24 further includes:

[0148] In response to determining that the cost function has not been minimized, the specific number of the field-faceted reflectors is reduced.

[0149] 26. The method according to aspect 24, wherein updating the first pupil profile based on the state of the first field-faceted mirror comprises:

[0150] The position of the first pupil faceted mirror corresponding to the minimum value on the resampled image is obtained from the resampled image, wherein the first pupil faceted mirror is one of a set of pupil faceted mirrors associated with the first field faceted mirror; and

[0151] The first pupil contour is updated by setting the first position on the first pupil profile corresponding to the first pupil faceted mirror to a first value, and setting the positions of the remaining pupil faceted mirrors associated with the first pupil faceted mirror to a second value.

[0152] 27. The method according to aspect 26, wherein the first value indicates the presence of source strength, and the second value indicates the absence of the source strength.

[0153] 28. The method according to aspect 26, wherein the resampled map is generated by interpolating the source optimization map based on lithographic performance in the pupil plane on an image representation of the mesh of the pupil faceted mirror.

[0154] 29. The method according to aspect 18, wherein the graph is obtained by:

[0155] Perform a source mask optimization process configured to determine a pupil profile representing a continuous source intensity distribution on the pupil plane; and

[0156] The source optimization map based on lithography performance is generated based on the source intensity gradient value determined during the source mask optimization process.

[0157] 30. The method according to aspect 18 further includes:

[0158] The second pupil profile is used to generate state information, wherein the state information indicates the state of the corresponding field-faceted mirror for printing a pattern on a substrate for each of a plurality of field-faceted mirrors.

[0159] 31. The method according to aspect 29 further includes:

[0160] The status information is input into the photolithography device; and

[0161] The state of the field-faceted reflector is adjusted based on the state information.

[0162] 32. The method according to aspect 30 further includes:

[0163] A patterning process is performed via the photolithography equipment to print a pattern corresponding to the target layout onto the substrate.

[0164] 33. An apparatus for determining a pupil profile for imaging a pattern onto a substrate during a photolithography process, the apparatus comprising:

[0165] Memory, the memory storing instruction sets; and

[0166] A processor configured to execute the set of instructions to cause the device to perform the method according to any of the foregoing aspects.

[0167] 34. A non-transitory computer-readable medium having instructions recorded thereon, which, when executed by a computer, perform the method according to any of the foregoing aspects.

[0168] In the block diagram, the components are depicted as discrete functional blocks, but the embodiments are not limited to systems in which the functions described herein are organized as illustrated. The functionality provided by each component may be provided by software or hardware modules organized differently from those currently described; for example, such software or hardware may be mixed, combined, replicated, decomposed, distributed (e.g., within a data center or geographically), or otherwise organized differently. The functions described herein may be provided by one or more processors of one or more computers that execute code stored on a tangible, non-transitory machine-readable medium. In some cases, a third-party content delivery network may host some or all of the information transmitted over the network, in which case, where the information (e.g., content) is referred to as being provided or otherwise provided, the information may be provided by sending an instruction to retrieve the information from the content delivery network.

[0169] Unless otherwise specified, as is obvious from the discussion, it should be understood that throughout this specification, the use of terms such as “processing,” “computational processing,” “computation,” “determining,” etc., refers to the actions or processes of a particular device (such as a dedicated computer or similar dedicated electronic processing / computing device).

[0170] Readers should understand that this application describes several inventions. These inventions have not been divided into multiple separate patent applications, but have been grouped into a single document because their related subject matter contributes to economy in the filing process. However, the individual advantages and aspects of these inventions should not be confused. In some cases, embodiments resolve all the deficiencies pointed out herein; however, it should be understood that the invention is independently useful, and some embodiments resolve only a subset of these problems, or provide other unmentioned benefits that would be obvious to a person skilled in the art upon review of this disclosure. Due to cost limitations, some inventions disclosed herein may not currently be claimed and may be claimed in subsequent applications (such as continuation applications or by amending the current claims). Similarly, due to space limitations, neither the abstract nor the summary section of this document should be considered a comprehensive list containing all such inventions or all aspects of such inventions.

[0171] It should be understood that the specification and drawings are not intended to limit this disclosure to the specific forms disclosed, but rather are intended to cover all modifications, equivalents and alternatives that fall within the spirit and scope of the invention as defined by the appended claims.

[0172] Modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art from this specification. Therefore, this specification and drawings are to be interpreted only as illustrative and intended to teach those skilled in the art the general manner of practicing the invention. It should be understood that the forms of the invention shown and described herein are to be exemplified as embodiments. Elements and materials shown and described herein may be substituted, parts and processes may be reversed or omitted, certain features may be used independently, and features of embodiments or embodiments may be combined, all of which will be apparent to those skilled in the art upon benefiting from this description. Changes may be made to the elements described herein without departing from the spirit and scope of the invention as set forth in the following claims. Titles used herein are for organizational purposes only and are not intended to limit the scope of this description.

[0173] As used herein, the word “may” is used in a permissive sense (i.e., meaning it is possible) rather than in a mandatory sense (i.e., meaning it must). The words “comprising,” “including,” and “including” mean, but are not limited to, those included. As used herein, the singular forms “a,” “an,” and “the” include plural pronouns unless explicitly stated otherwise. Thus, for example, references to an element “a” or “one” include combinations of two or more elements, even though other terms and phrases such as “one or more” are used for one or more elements. As used herein, unless otherwise specifically stated, the term “or” covers all possible combinations except those that are impractical. For example, if a component may comprise A or B, then unless otherwise specifically stated or impractical, the component may comprise A, or B, or A and B. As a second example, if a component may comprise A, B, or C, then unless otherwise specifically stated or impractical, the component may comprise A, or B, or C, or A and B, or A and C, or B and C, or A and B and C.

[0174] Terms describing conditional relationships (e.g., "in response to X, Y", "in the case of X, Y", "if X, Y", "when X, Y", etc.) include causal relationships, where the antecedent is a necessary causal condition, a sufficient causal condition, or a contributing causal condition to the outcome. For example, "state X occurs when condition Y is obtained" is interchangeable with "X occurs only when Y is obtained" and "X occurs in the case of Y and Z". Such conditional relationships are not limited to results immediately following the antecedent, as some results may be delayed, and in a conditional statement, the antecedent is related to its outcome, such as the antecedent being related to the probability of the outcome occurring. Statements that map multiple attributes or functions to multiple objects (e.g., one or more processors performing steps A, B, C, and D) include all attributes or functions mapped to all these objects, as well as subsets of attributes or functions mapped to subsets of attributes or functions (e.g., each of all processors performs steps A through D, and processor 1 performs step A, processor 2 performs a portion of steps B and C, and processor 3 performs a portion of steps C and D), unless otherwise stated. Furthermore, statements that a value or action is "based on" another condition or value include cases where the condition or value is the only factor and cases where the condition or value is one of multiple factors. Unless otherwise stated, statements that "each" instance of a certain set has a certain property should not be interpreted as excluding cases where some other identical or similar members in a larger set do not have that property; that is, "each" does not necessarily mean "every" and "every single". References to range selection include the endpoints of the range.

[0175] In the above description, any process, description, or block in the flowchart should be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a specific logical function or step in the process, and alternative implementations are included within the scope of exemplary embodiments of this improvement, wherein, depending on the function involved, the functions may be performed in a different order than the functions shown or discussed, including substantially simultaneous or in reverse order, as will be understood by those skilled in the art.

[0176] Where certain U.S. patents, U.S. patent applications, or other materials (e.g., articles) have been incorporated by reference, the text of such U.S. patents, U.S. patent applications, and other materials is incorporated by reference only if there is no conflict between such materials and the statements and figures set forth herein. If such conflict occurs, any such conflicting text so incorporated by reference to U.S. patents, U.S. patent applications, and other materials is not incorporated herein by reference.

[0177] While certain embodiments have been described, these embodiments have been presented by way of example only and are not intended to limit the scope of this disclosure. In fact, the novel methods, apparatuses, and systems described herein can be embodied in a variety of other forms; furthermore, various omissions, substitutions, and changes can be made to the form of the methods, apparatuses, and systems described herein without departing from the spirit of this disclosure. The appended claims and their equivalents are intended to cover such forms or modifications that fall within the scope and spirit of this disclosure.

Claims

1. A non-transitory computer-readable medium having instructions recorded thereon, the instructions, when executed by a computer, implementing a method for determining a pupil profile for imaging a pattern onto a substrate during photolithography, the method comprising: Obtain a first pupil profile for printing a pattern onto a substrate using photolithography equipment; Obtain data indicating the relationship between changes in lithographic performance across the pupil plane and changes in the source; as well as The first pupil contour is optimized based on the data to generate the second pupil contour.

2. The medium according to claim 1, wherein, The first pupil profile is a discrete pupil profile.

3. The medium according to claim 1, wherein, The data indicates a graph of the gradient of the source variables of the lithography apparatus, wherein each value on the graph indicates the effect of the source intensity variation at a specific location on the pupil plane on the lithography performance.

4. The medium according to claim 3, wherein, The diagram was obtained in the following way: Perform a source mask optimization process configured to determine a pupil profile representing a continuous source intensity distribution on the pupil plane; as well as The graph is generated based on the source intensity gradient values ​​determined during the source mask optimization process.

5. The medium according to claim 4, wherein, The source mask optimization process is configured to optimize the pupil profile based on edge placement error.

6. The medium of claim 3, the method further comprising discretizing the first pupil profile, and wherein, The optimization includes iteratively optimizing the first pupil contour based on the graph to generate the second pupil contour.

7. The medium according to claim 6, wherein, The cost function is iteratively optimized based on the combination of the graph and the first pupil profile.

8. The medium according to claim 7, wherein, The cost function is the product of the intensity value at each selected location in the first pupil profile and the value of the graph at the selected location.

9. The medium according to claim 6, wherein, Each iteration includes: For each of the multiple field-faceted mirrors in a specific number of field-faceted mirrors of the lithography apparatus, the state of the first field-faceted mirror is determined based on the values ​​in the graph; The first pupil profile is updated based on the state of the first faceted mirror; and Based on the state, determine whether the cost function is reduced.

10. The medium according to claim 9, wherein, Updating the first pupil profile based on the state of the first faceted mirror includes: The position of the first pupil faceted mirror corresponding to the minimum value on the resampled image is obtained from the resampled image, wherein the first pupil faceted mirror is one of a set of pupil faceted mirrors associated with the first field faceted mirror; and The first pupil contour is updated by setting the first position on the first pupil profile corresponding to the first pupil faceted mirror to a first value, and setting the positions of the remaining pupil faceted mirrors associated with the first pupil faceted mirror to a second value.

11. The medium according to claim 10, wherein, The first value indicates the presence of source strength, and the second value indicates the absence of the source strength.

12. The medium according to claim 10, wherein, The resampled image is generated by interpolating the image onto the grid of the pupil facet mirror in the pupil plane.

13. The medium according to claim 1, wherein, The method further includes: The second pupil profile is used to generate state information, wherein the state information indicates the state of the corresponding field-faceted mirror for printing a pattern on a substrate for each of a plurality of field-faceted mirrors.

14. The medium according to claim 13, wherein, The method further includes: The status information is input into the photolithography device; and The state of the field-faceted reflector is adjusted based on the state information.

15. The medium according to claim 14, wherein, The method further includes: A patterning process is performed via the photolithography equipment to print a pattern corresponding to the target layout onto the substrate.

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