Reticle adjustment for lithography applications

Abstract

A method for adjusting a reticle includes determining the target operating temperature of the reticle in use. A method includes controlling the temperature of the reticle to approach the target operating temperature of the reticle in use. A method includes exposing the reticle to radiation to perform a manufacturing process.

Description

[Technical Field]

[0001] (Cross-reference of related applications)

[0001] This application claims priority to U.S. Patent Application No. 63 / 522,603, filed on 22 June 2023. This application is incorporated in its entirety by reference.

[0002]

[0002] This disclosure relates to the processing and adjustment of reticles, for example, to the adjustment of reticles in lithography apparatus and systems. [Background technology]

[0003]

[0003] A lithography apparatus is a machine built to apply a desired pattern to a substrate. Lithography apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A lithography apparatus can, for example, project a pattern of a patterning device (e.g., a mask, a reticle) onto a layer of radiation-sensitive material (photoresist, or simply "resist") provided on a substrate.

[0004]

[0004] To project a pattern onto a substrate, a lithography apparatus can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of the features that can be formed on the substrate. For example, using a lithography apparatus that uses extreme ultraviolet (EUV) radiation with a wavelength in the range of 4 to 20 nm, such as 6.7 nm or 13.5 nm, allows for the formation of smaller features on the substrate than a lithography apparatus that uses radiation with a wavelength of, for example, 193 nm.

[0005]

[0005] A lithography apparatus may include a patterning device (e.g., a mask or reticle). An image can be formed on a substrate by transmitting radiation through the patterning device or by reflecting radiation through the patterning device. A film assembly, also called a pellicle, can be provided to protect the patterning device from airborne particles and other forms of contamination. Contamination of the surface of the patterning device may cause manufacturing defects in the substrate.

[0006]

[0006] During use, the reticle is exposed to the radiation beam, which can heat the reticle. To control the temperature of the reticle, cooling can be provided to the reticle, which can be in the form of liquid cooling. The reticle can be supported by a reticle clamp that holds the reticle in place. Although the temperature of the reticle is controllable, the shape of the reticle changes when exposed to the radiation beam, which can cause deformation of the reticle and lead to overlay problems. Some deformation can be corrected by alignment adjustments, but there may be parts of deformation that cannot be corrected by existing methods and therefore cannot be corrected.

[0007]

[0007] Reticles used in lithography wafer processing are subject to conflicting heating and cooling during use. For example, a reticle may be subject to local heating (for example, due to radiation used in wafer processing heating a portion of the reticle) and local cooling (for example, indirectly by contact with a chuck or clamp that is actively cooled to avoid overheating, or directly by blowing cold air onto the reticle). Furthermore, a reticle may undergo large temperature changes during use, heating from an initial temperature close to room temperature to an operating temperature significantly higher than room temperature. As a result, large thermal stress can occur in the reticle during exposure for wafer processing, potentially leading to overlay errors.

[0008]

[0008] As a specific example, the temperature of the reticle can change dramatically during the exposure of the first few wafers in a wafer processing lot. As a result, the reticle in later wafers in a lot is hotter than in the first few, resulting in an "intra-lot" overlay error. A similar effect can be seen in different fields within the same wafer, where the reticle in later fields of a single wafer is hotter than in the first few fields, resulting in an "intra-wafer" overlay. Such temperature changes of the reticle during exposure cause thermal distortion of the reticle, which can lead to in-plane and out-of-plane deformation of the reticle and create the possibility of slippage. These problems can be exacerbated when reticles need to be replaced frequently in wafer processing.

[0009]

[0009] Reticle alignment modeling provides only limited compensation for the above problems. Another method is needed to reduce thermally induced overlay errors. [Overview of the Initiative]

[0010]

[0010] Therefore, it is desirable to reduce the thermal strain experienced by the reticle during use, thereby reducing the resulting overlay errors. As will be discussed below, the reticle and the temperature of the reticle can be controlled to approximately the target operating temperature of the reticle before exposure is performed and wafer processing begins.

[0011]

[0011] In some embodiments, the reticle or reticle blank may include a low-deformation material. In this case, the reticle or reticle blank has a zero-crossing temperature (ZCT) profile and a ZCT gradient profile, and at least one of the ZCT profile and the ZCT gradient profile is non-uniform.

[0012]

[0012] Reticles and reticle blanks used in lithography apparatus and processes may include ultra-low expansion (ULE) glass. ULE can be used because it undergoes very little change in shape when its temperature changes compared to other materials. During use, ULE glass can be heated by absorbing a large amount of energy from the radiation beam. Although the temperature of the reticle can be controlled by cooling, some heating can still occur. The reticle can be supported by a reticle clamp, but it may deform when constrained by the clamp. Some of these deformations can be corrected by aligning the reticle using reference marks on the reticle, but higher-order deformations cannot be corrected by existing means.

[0013]

[0013] Some embodiments of the present disclosure address this drawback by providing a reticle or reticle blank in which one or both of the zero-crossing temperature profile and the ZCT gradient profile are non-uniform. The zero-crossing temperature is the temperature or temperature range in which the thermal expansion of the material constituting the reticle crosses zero. Some materials, such as ULE glass, have a temperature or temperature range in which their coefficient of thermal expansion crosses zero. Around the zero-crossing temperature, the material is dimensionally stable with respect to temperature fluctuations. The zero-crossing temperature gradient is the rate at which the coefficient of thermal expansion changes around the zero-crossing temperature. Existing reticles and reticle blanks are manufactured to have as uniform a ZCT profile as possible. The ZCT gradient profile is based on the length of the annealing process of the material used to form the reticle or reticle blank. This can lead to uncorrectable deformation in use. Some embodiments of the present disclosure provide a reticle or reticle blank having a non-uniform ZCT profile and / or ZCT gradient profile so that different parts of the reticle or reticle blank deform differently during use. This allows the reticle or reticle blank to be configured to have various deformation characteristics during use, and to limit the degree of deformation that cannot be corrected.

[0014]

[0014] The reticle or reticle blank has x, y, and z directions. In some embodiments, at least one of the ZCT profile and the ZCT gradient profile may vary in the y direction. The ZCT profile and / or ZCT gradient profile in the y direction may be configured to be a low-order profile, such as a quadratic profile, which can be easily corrected. If there is no variation in the ZCT profile, the deformation is of a higher order than quadratic and cannot be easily corrected.

[0015]

[0015] In some embodiments, at least one of the ZCT profile and the ZCT gradient profile varies in the region adjacent to the edge of the reticle or reticle blank. Varying the ZCT profile and / or ZCT gradient profile adjacent to the edge of the reticle or reticle blank has been shown to be advantageous in reducing uncorrectable deformation. While not bound by scientific theory, it is thought that the deformation of the edge of the reticle or reticle blank can change in context when supported by a reticle clamp. By varying the ZCT profile and / or ZCT gradient profile as described above, the deformation of the edge of the reticle or reticle blank can be controlled.

[0016]

[0016] In some embodiments, the ZCT of the reticle or reticle blank is elevated at at least one boundary of the reticle or reticle blank. It has been shown that an overlay improvement of more than 35% can be obtained by having an elevated ZCT at the boundary of the reticle. According to some embodiments, the ZCT of the reticle or reticle blank has a range of about ±1°C, about ±2°C, about ±3°C, about ±4°C, about ±5°C, about ±6°C, about ±7°C, about ±8°C, about ±9°C, or about ±10°C. By having a wider range of ZCT, the reticle or reticle blank is dimensionally stable over a wider temperature range. In some embodiments, the ZCT gradient can be about 0.5 ppb / K2 to about 2.5 ppb / K2. The ZCT can be about 1.0 ppb / K2 to about 2.0 ppb / K2. In some embodiments, the ZCT profile and / or ZCT gradient profile have at least one axis of symmetry. The axes of symmetry can be the y-axis, x-axis, and / or z-axis.

[0017]

[0017] In some embodiments, the reticle clamp may include a reticle such as that described herein.

[0018]

[0018] In some embodiments, the lithography apparatus may include a reticle or reticle clamp according to a first or second embodiment of the present disclosure. The lithography apparatus may be a deep ultraviolet (DUV) or extreme ultraviolet (EUV) lithography apparatus.

[0019]

[0019] In some embodiments, a method for mitigating irreparable deformation of a reticle or reticle blank may include providing a reticle or reticle blank having at least one of a ZCT profile and a ZCT gradient profile that is non-uniform throughout the reticle or reticle blank. The non-uniform ZCT profile and / or ZCT gradient profile can reduce the amount of irreparable deformation of the reticle or reticle blank, thereby reducing overlay errors. The method may include varying at least one of the ZCT profile and the ZCT gradient profile in areas adjacent to the edges of the reticle or reticle blank.

[0020]

[0020] In some embodiments, a method for generating a reticle or reticle blank for a lithography process may include: modeling the deformation of the reticle or reticle blank under operating conditions; calculating a ZCT profile and / or ZCT gradient profile of the reticle or reticle blank to reduce the modeled uncorrectable deformation based on the deformation modeling; optionally repeating these steps until the modeled uncorrectable deformation is reduced to a predetermined level; outputting an optimized ZCT profile and / or ZCT gradient profile of the reticle or reticle blank; and generating a reticle or reticle blank having the optimized ZCT profile and / or ZCT gradient profile.

[0021]

[0021] According to some aspects, non-correctable deformations of a reticle or reticle blank can be reduced by adjusting the ZCT profile and / or ZCT gradient profile across the entire reticle or reticle blank. In other words, the ZCT and ZCT gradient can be made different at different parts of the reticle or reticle blank. By modeling the deformation of the reticle or reticle blank, the ZCT profile and / or ZCT gradient profile can be adjusted to reduce non-correctable deformations, and then a reticle or reticle blank having a desired ZCT profile and / or ZCT gradient profile can be generated.

[0022]

[0022] In some aspects, the method includes determining a target operating temperature of a reticle in use, controlling the temperature of the reticle to approach the target operating temperature of the reticle in use, and exposing the reticle to radiation to perform a manufacturing process.

[0023]

[0023] In some aspects, the method includes directly measuring the operating temperature of a precursor reticle or a reticle used in a previous manufacturing process. In some aspects, the method includes modeling one or more target operating conditions of the reticle.

[0024]

[0024] In some aspects, the control of the temperature of the reticle can be performed during writing of the reticle, before loading the reticle into the apparatus to perform a manufacturing process, after loading the reticle into the apparatus to perform a manufacturing process, and / or during the manufacturing process. In some aspects, the control of the temperature of the reticle can be performed while the reticle is stored in a reticle library, a reticle handler, or a turret, while the reticle is mounted on a stage or a clamp or a chuck, during the overhead time between exposures of two wafers, and / or during scanning and / or exposure of the reticle.

[0025]

[0025] In some embodiments, one or more areas of the reticle are actively heated during scanning and / or exposure of the wafer. In some embodiments, one or more areas of the reticle are actively heated by heating the reticle using the radiation used in the manufacturing process or by using heat supplied from a source other than the radiation used in the manufacturing process. In some embodiments, a gas jet or infrared light can be used to heat the reticle.

[0026]

[0026] In some embodiments, the method further includes measuring the temperature of the chuck or clamp, modeling the future temperature of the chuck or clamp based on the result of the measurement of the temperature of the chuck or clamp, and controlling the temperature of the chuck or clamp based on the modeling of the future temperature of the chuck or clamp. In another embodiment, this includes modeling the operating temperature of the clamp and / or chuck.

[0027]

[0027] In some embodiments, a system for preconditioning a reticle includes a housing configured to hold one or more reticles, one or more heating elements configured to heat at least one of the one or more reticles, and a controller configured to control the temperature of at least one reticle to a predetermined temperature using the one or more heating elements before exposing the reticle to radiation to perform a manufacturing process. The predetermined temperature can be the predicted operating temperature of the reticle during exposure to the radiation for performing the manufacturing process. The predicted operating temperature of the reticle can be based on the predicted dose of radiation to the reticle.

[0028]

[0028] Additional features of various aspects of the present disclosure are described in detail below with reference to the accompanying drawings. It should be noted that the present disclosure is not limited to the specific aspects described herein. Such aspects are presented herein for illustrative purposes only. Based on the teachings contained herein, additional aspects will be apparent to those skilled in the art. [Brief explanation of the drawing]

[0029]

[0029] The accompanying drawings incorporated herein and forming part of the specification are intended to illustrate the disclosure, to illustrate the principles of the disclosure together with the description, and to enable a person skilled in the art to make and use the embodiments described herein.

[0030] [Figure 1]

[0030] Lithography apparatus according to several embodiments is shown. [Figure 2A]

[0031] Several embodiments of reflective lithography apparatus are shown. [Figure 2B]

[0032] Several embodiments of a transmissive lithography apparatus are shown. [Figure 2C]

[0033] Lithographic cells according to several embodiments are shown. [Figure 3]

[0034] The deformation of the reticle within the reticle clamp according to several embodiments is shown. [Figure 4A-4B]

[0035] The deformation of a reticle having a nominal uniform ZCT and the deformation of a reticle having a secondary ZCT profile in the y-direction are shown according to several embodiments. [Figure 5]

[0036] One exemplary embodiment of a reticle or reticle blank according to several aspects is shown. [Figure 6]

[0037] Several types of reticle stages are shown. [Figure 7]

[0037] Several embodiments of the reticle stage are shown. [Figure 8]

[0038] Several embodiments of reticle exchange devices are shown. [Figure 9]

[0038] Several embodiments of reticle exchange devices are shown. [Figure 10]

[0039] A flowchart illustrating methods for adjusting the reticle according to several embodiments is shown. [Figure 11A]

[0040] Several configurations for adjusting the reticle are shown. [Figure 11B]

[0040] Several configurations for adjusting the reticle are shown. [Figure 11C]

[0040] Several configurations for adjusting the reticle are shown. [Figures 12A-12B]

[0041] The following describes wafer heating during wafer processing without reticle adjustment and wafer heating during wafer processing with reticle adjustment, according to several embodiments. [Figure 13]

[0042] A flowchart illustrating methods for adjusting the reticle according to several embodiments is shown.

[0031]

[0043] The features of this disclosure will become even clearer when the detailed description below is read in conjunction with the drawings. Throughout the drawings, similar reference numerals identify corresponding elements. In the drawings, similar reference numerals generally indicate identical elements, functionally similar elements, and / or structurally similar elements. Also, generally, the leftmost one or more digits of a reference numeral identify the drawing in which that reference numeral first appears. Unless otherwise indicated, the drawings provided throughout this disclosure should not be interpreted as being at a fixed scale. [Modes for carrying out the invention]

[0032]

[0044] The embodiments described herein, and the references thereto such as “one embodiment,” “a certain embodiment,” “an exemplary embodiment,” and “an example embodiment,” indicate that while the described embodiments may include certain features, structures, or characteristics, not all embodiments necessarily include those specific features, structures, or characteristics. Furthermore, such phrases do not necessarily refer to the same embodiment. In addition, if certain features, structures, or characteristics are described in relation to one embodiment, it will be understood that, whether explicitly stated or not, it is within the knowledge of those skilled in the art to implement such features, structures, or characteristics in relation to other embodiments.

[0033]

[0045] To facilitate explanation, spatially relative terms such as "beneath," "below," "lower," "above," "on," and "upper" may be used herein to describe the relationship between one element or feature shown in the figure and one or more other elements or features. Spatially relative terms are intended to encompass various orientations of the device during use or operation, in addition to the orientation shown in the figure. The device may be oriented in other ways (rotated 90 degrees or otherwise), and accordingly, the spatially relative descriptive terms used herein may be interpreted similarly.

[0034]

[0046] Terms such as "about" and "approximately" may be used herein to indicate a value of a given quantity that may vary based on a particular technique. Based on a particular technique, terms such as "about" and "approximately" may indicate a value of a given quantity that varies within, for example, 10 to 30% of that value (e.g., ±10%, ±20%, or ±30% of that value).

[0035]

[0047] Aspects of this disclosure can be implemented in hardware, firmware, software, or any combination thereof. Alternatively, aspects of this disclosure can be implemented as instructions stored on a computer-readable medium that 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, the electrical, optical, acoustic, or other forms of propagating signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Furthermore, firmware, software, routines, and / or instructions may be described herein as performing specific actions. However, such descriptions are merely for convenience, and such actions may be obtained as a result of a computing device, processor, controller, or other device executing firmware, software, routines, instructions, etc. The term “machine-readable medium” may be interchangeable with similar terms such as “computer program product,” “computer-readable medium,” and “non-temporary computer-readable medium.” The term “non-temporary” can be used herein to characterize one or more forms of computer-readable medium, excluding temporary propagating signals.

[0036]

[0048] However, before describing such embodiments in more detail, it is useful to present exemplary environments in which embodiments of this disclosure can be implemented.

[0037]

[0049] Exemplary lithography system

[0050] Figure 1 shows a lithography system according to the present invention. The lithography system includes a radiation source SO and a lithography apparatus LA. The radiation source SO is configured to generate an extreme ultraviolet (EUV) radiation beam B. The lithography apparatus LA comprises an illumination system IL, a support structure MT configured to support a patterning device MA (e.g., a mask), a projection system PS, and a substrate table WT configured to support a substrate W. The illumination system IL is configured to adjust the radiation beam B before it is incident on the patterning device MA. The projection system is configured to project the radiation beam B (which is patterned by the mask MA at this point) onto the substrate W. The substrate W may contain a previously formed pattern. If this is the case, the lithography apparatus aligns the patterned radiation beam B with the previously formed pattern on the substrate W. In this embodiment, a pellicle 15 protecting the patterning device MA is shown in the path of the radiation. The pellicle 15 can be placed in any required position and it will be acknowledged that it may be used to protect any of the mirrors in the lithography apparatus. The patterning device MA is sometimes called a reticle. The support structure MT is sometimes called a reticle stage.

[0038]

[0051] The radiation source SO, the illumination system IL, and the projection system PS can all be constructed and positioned to be isolated from the external environment. A gas (e.g., hydrogen) at a pressure lower than atmospheric pressure may be provided within the radiation source SO. A vacuum may be provided within the illumination system IL and / or the projection system PS. A small amount of gas (e.g., hydrogen) at a pressure sufficiently lower than atmospheric pressure may be provided within the illumination system IL and / or the projection system PS.

[0039]

[0052] The radiation source SO shown in Figure 1 is of a type that can be called a laser-generated plasma (LPP) source. The laser, for example, a CO2 laser, is arranged to deposit energy onto a fuel such as tin (Sn) supplied from a fuel ejector via the laser beam. In the following description, tin is mentioned, but any suitable fuel can be used. The fuel can be, for example, in liquid form, or a metal or alloy. The fuel ejector may have a nozzle configured to guide tin, for example, in the form of droplets, along a trajectory toward the plasma-forming region. The laser beam is incident on the tin in the plasma-forming region. The deposition of laser energy onto the tin generates plasma in the plasma-forming region. During the de-excitation and recombination of plasma ions, radiation, including EUV radiation, is emitted from the plasma.

[0040]

[0053] EUV radiation is collected and focused by a near-normal incident radiation collector (sometimes more commonly called a normal incident radiation collector). The collector may have a multilayer structure arranged to reflect EUV radiation (e.g., EUV radiation with a desired wavelength such as 13.5 nm). The collector may have an elliptical configuration with two elliptical foci. The first focus may be in the plasma-forming region, and the second focus may be an intermediate focus. This will be discussed below.

[0041]

[0054] The laser may be separated from the radiation source SO. If this is the case, the laser beam can be transferred from the laser to the radiation source SO by a beam delivery system (not shown) including, for example, a suitable guide mirror and / or beam expander and / or other optical systems. The laser and radiation source SO can be considered together as a radiation system.

[0042]

[0055] The radiation reflected by the collector forms radiation beam B. Radiation beam B is focused at a point to form an image of the plasma-forming region, which acts as a virtual radiation source for the illumination system IL. The point at which radiation beam B is focused can be called the intermediate focus. The radiation source SO is positioned such that the intermediate focus is located at or near the aperture of the closed structure of the radiation source.

[0043]

[0056] The radiant beam B travels from the radiation source SO into an illumination system IL configured to adjust the radiant beam. The illumination system IL may include a faceted field mirror device 10 and a faceted pupil mirror device 11. Both the faceted field mirror device 10 and the faceted pupil mirror device 11 give the radiant beam B a desired cross-sectional shape and a desired angular distribution. The radiant beam B exits the illumination system IL and is incident on a patterning device MA held by a support structure MT. The patterning device MA reflects the radiant beam B and imparts a pattern. The illumination system IL may also include other mirrors or devices in addition to, or instead of, the faceted field mirror device 10 and the faceted pupil mirror device 11.

[0044]

[0057] After being reflected from the patterning device MA, the patterned radiation beam B is incident on the projection system PS. The projection system comprises several mirrors 13, 14 configured to project the radiation beam B onto a substrate W held by a substrate table WT. The projection system PS can form an image of a feature smaller than the corresponding feature on the patterning device MA by applying a reduction factor to the radiation beam. For example, a reduction factor of 4 can be applied. In Figure 1, the projection system PS has two mirrors 13, 14, but the projection system can include any number of mirrors (e.g., six mirrors).

[0045]

[0058] The radiation source SO shown in Figure 1 may include components not shown. For example, a spectral filter may be provided within the radiation source. The spectral filter may be substantially transparent to EUV radiation but substantially block radiation of other wavelengths, such as infrared radiation.

[0046]

[0059] If the patterning device (MA) is left unprotected, contamination may necessitate cleaning or disposal of the MA. Cleaning the MA interrupts valuable manufacturing time, and disposal is costly. Replacing the MA also interrupts valuable manufacturing time.

[0047]

[0060] Figures 2A and 2B show lithography apparatus 200 and lithography apparatus 200', respectively, which can carry out embodiments of the present disclosure. Lithography apparatus 200 and lithography apparatus 200' each include the following structures: an illumination system (illuminator) IL configured to adjust a radiation beam B (e.g., deep ultraviolet or extreme ultraviolet radiation); a support structure (e.g., mask table) MT connected to a first positioner PM configured to support a patterning device (e.g., a mask, reticle, or dynamic patterning device) MA and to precisely position the patterning device MA; and a substrate table (e.g., wafer table) WT connected to a second positioner PW configured to hold a substrate (e.g., a resist-coated wafer) W and to precisely position the substrate W. Lithography apparatus 200 and 200' also include a projection system PS configured to project the pattern applied to the radiation beam B by the patterning device MA onto a target portion (e.g., including one or more dies) C of the substrate W. In lithography apparatus 200, the patterning device MA and projection system PS are reflective. In lithography apparatus 200', the patterning device MA and projection system PS are transmissive.

[0048]

[0061] The illumination system IL may include various types of optical components, such as refractive, reflective, reflector-refracting, magnetic, electromagnetic, electrostatic, and / or other types of optical components, or any combination thereof, for guiding, shaping, or controlling the radiant beam B.

[0049]

[0062] 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 lithography apparatus 200 and 200', and other conditions such as whether the patterning device MA is held in a vacuum environment. The support structure MT can hold the patterning device MA using mechanical, vacuum, electrostatic, or other clamping techniques. The support structure MT can be, for example, a frame or a table, and can be fixed or movable. By using sensors, the support structure MT can ensure that the patterning device MA is in the desired position relative to the projection system PS, for example.

[0050]

[0063] The term "patterning device" (MA) should be broadly interpreted to refer to any device that can be used to impart a pattern to the cross-section of a radiation beam B in order to generate a pattern on a target portion C of a substrate W. The pattern imparted to the radiation beam B may correspond to a specific functional layer within the device that is generated on the target portion C to form an integrated circuit.

[0051]

[0064] The patterning device MA can be transmissive (lithography apparatus 200' in Figure 2B) or reflective (lithography apparatus 200 in Figure 2A). Examples of patterning devices MA include reticles, masks, programmable mirror arrays, or programmable LCD panels. Masks are well known in lithography and include various mask types such as binary masks, Levenson (alternating) phase-shift masks, halftone (attenuated) phase-shift masks, and various hybrid mask types. An example of a programmable mirror array is a matrix array of small mirrors, each of which can be individually tilted to reflect the incident radiation beam in a different direction. The tilted mirrors impart a pattern to the radiation beam B reflected by the matrix of small mirrors.

[0052]

[0065] The term "projection system" PS may encompass any type of projection system, including refractive optical systems, reflective optical systems, reflecting refractive optical systems, magneto-optical systems, electromagnetic optical systems, and electrostatic optical systems, or any combination thereof, depending on the exposure radiation used or other factors such as the use of immersion liquid or vacuum on the substrate W. A vacuum environment may be used for EUV or electron beam radiation because other gases may absorb too much radiation or electrons. Therefore, a vacuum environment can be provided throughout the beam path using vacuum walls and vacuum pumps.

[0053]

[0066] The lithography apparatus 200 and / or lithography apparatus 200' may be of a type having two (dual stage) or more substrate tables WT (and / or two or more mask tables). In such a “multistage” machine, additional substrate tables WT can be used in parallel, or preparation steps can be performed on one or more other tables while one or more substrate tables WT are being used for exposure. In some situations, the additional tables may not be substrate tables WT.

[0054]

[0067] The lithography apparatus may be of a type that can cover at least a portion of the substrate with a liquid having a relatively high refractive index, such as water, to fill the space between the projection system and the substrate. It is also possible to provide immersion liquid to other spaces within the lithography apparatus, such as between the mask and the projection system. Immersion techniques are well known in the art for increasing the numerical aperture of the projection system. As used herein, the term "immersion" does not mean that the substrate or other structure must be submerged in liquid. For example, liquid can be placed between the projection system and the substrate during exposure.

[0055]

[0068] Referring to Figures 2A and 2B, the illuminator IL receives the radiation beam from the radiation source SO. For example, if the radiation source SO is an excimer laser, the radiation source SO and the lithography apparatus 200, 200' can be separate physical entities. In such a case, the radiation source SO is not considered to form part of the lithography apparatus 200 or 200', and the radiation beam B is delivered from the radiation source SO to the illuminator IL using a beam delivery system BD (Figure 2B), which includes, for example, appropriate guide mirrors and / or beam expanders. In other cases, for example, if the radiation source SO is a mercury lamp, the radiation source SO may be an integral part of the lithography apparatus 200, 200'. The radiation system may include the radiation source SO, the illuminator IL, and / or the beam delivery system BD.

[0056]

[0069] The illuminator IL may include an adjuster AD (Figure 2B) for adjusting the angular intensity distribution of the radiated beam. Typically, at least the outer radius range and / or inner radius range (commonly referred to as "σ-outer" and "σ-inner," respectively) of the intensity distribution within the pupil plane of the illuminator can be adjusted. Furthermore, the illuminator IL may include various other components (Figure 2B), such as an integrator IN and a capacitor CO. Using the illuminator IL, the radiated beam B can be adjusted to have the desired uniformity and intensity distribution in cross-section.

[0057]

[0070] Referring to Figure 2A, the radiant beam B is incident on a patterning device (e.g., a mask) MA held on a support structure (e.g., a mask table) MT, and a pattern is applied by the patterning device MA. In the lithography apparatus 200, the radiant 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 radiant beam B passes through a projection system PS, which focuses the radiant beam B onto a target portion C of the substrate W. A second positioner PW and a position sensor IF2 (e.g., an interference device, a linear encoder, or a capacitance sensor) can be used to precisely move the substrate table WT (e.g., to position various target portions C within the path of the radiant beam B). Similarly, a first positioner PM and another position sensor IF1 can be used to precisely position the patterning device (e.g., a mask) MA relative to the path of the radiant beam B. The patterning device (e.g., a mask) MA and the substrate W can be positioned using mask alignment marks M1, M2 and substrate alignment marks P1, P2.

[0058]

[0071] Referring to Figure 2B, the 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 crossing the mask MA, the radiation beam B passes through a projection system PS, which focuses the beam onto a target portion C of the substrate W. The projection system has a pupil-conjugate PPU relative to the illumination system pupil IPU. A portion of the radiation originates from the intensity distribution in the illumination system pupil IPU, crosses the mask pattern without being affected by diffraction, and generates an image of the intensity distribution in the illumination system pupil IPU.

[0059]

[0072] The projection system PS projects an image of a mask pattern MP onto a photoresist layer coated on a substrate W. This image is formed by a diffracted beam generated from the mask pattern MP by radiation from the intensity distribution. For example, the mask pattern MP may include an array of lines and space. Diffraction of radiation different from zero-order diffraction in the array generates a re-directional diffracted beam whose direction changes perpendicular to the lines. The non-diffracted beam (i.e., the so-called zero-order diffracted beam) traverses the pattern without changing its propagation direction. The zero-order diffracted beam reaches the pupil conjugate PPU upstream of the pupil conjugate PPU of the projection system PS, traversing the upper lens or upper lens group of the projection system PS. The portion of the intensity distribution related to the zero-order diffracted beam within the plane of the pupil conjugate PPU is an image of the intensity distribution in the illumination system pupil IPU of the illumination system IL. For example, an aperture device PD is located on or substantially on the plane containing the pupil conjugate PPU of the projection system PS.

[0060]

[0073] The projection system PS is arranged to capture a zero-order diffraction beam, a primary diffraction beam, and / or higher-order diffraction beams (not shown) (e.g., using lenses or lens groups L). In some embodiments, the resolution-enhancing effect of dipole illumination can be utilized by using dipole illumination to image a line pattern extending perpendicular to the line. For example, the primary diffraction beam interferes with the corresponding zero-order diffraction beam at the wafer W level to produce an image of the line pattern MP with the highest possible resolution and process window (i.e., usable depth of focus combined with an acceptable exposure dose deviation). In some embodiments, astigmatism can be reduced by providing radiating poles (not shown) in opposing quadrants of the illumination system pupil IPU. Furthermore, in some embodiments, astigmatism can be reduced by blocking the zero-order beam in the projection system pupil conjugate PPU related to the radiating poles of the opposing quadrants. This is described in more detail in U.S. Patent No. 7,511,799B2 issued March 31, 2009, which is incorporated in its entirety by reference.

[0061]

[0074] A second positioner PW and position sensor IFD (e.g., an interference device, linear encoder, or capacitive sensor) can be used to precisely move the substrate table WT (e.g., to position various target portions C within the path of the radiation beam B). Similarly, a first positioner PM and another position sensor (not shown in Figure 1B) can be used to precisely position the mask MA relative to the path of the radiation beam B (e.g., after mechanical removal from the mask library or during scanning).

[0062]

[0075] Generally, the movement of the mask table MT can be achieved using long-stroke modules (coarse positioning) and short-stroke modules (fine positioning) that form part of the first positioner PM. Similarly, the movement of the substrate table WT can be achieved using long-stroke modules and short-stroke modules that form part of the second positioner PW. In the case of a stepper (as opposed to a scanner), the mask table MT can be connected to or fixed only to short-stroke actuators. The mask MA and substrate W can be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. The substrate alignment marks (as shown in the figure) occupy dedicated target areas, but they may also be positioned in the space between the target areas (known as scribe line alignment marks). Similarly, in situations where multiple dies are provided on the mask MA, the mask alignment marks may be positioned between those dies.

[0063]

[0076] The mask table MT and patterning device MA may be placed inside the vacuum chamber V. In this case, an in-vacuum robot IVR can be used to move the patterning device, such as a mask, inside and outside the vacuum chamber. Alternatively, if the mask table MT and patterning device MA are outside the vacuum chamber, an out-of-vacuum robot can be used for various transport tasks, similar to the in-vacuum robot IVR. Both in-vacuum and out-of-vacuum robots can be calibrated to smoothly move any payload (e.g., a mask) to a fixed kinematic mount on a transfer station.

[0064]

[0077] Lithography devices 200 and 200' can be used in at least one of the following modes:

[0065] 1. In step mode, the support structure (e.g., mask table) MT and substrate table WT are kept essentially stationary, while the entire pattern applied to the radiation beam B is projected onto the target portion C in one pass (i.e., single static exposure). Next, the substrate table WT is moved in the X and / or Y directions so that another target portion C can be exposed.

[0066] 2. In scan mode, the support structure (e.g., mask table) MT and the substrate table WT are scanned synchronously, while the pattern applied to the radiation beam B is projected onto the target portion C (i.e., single dynamic exposure). The speed and direction of the substrate table WT relative to the support structure (e.g., mask table) MT can be determined by the magnification (reduction) and image inversion characteristics of the projection system PS.

[0067] 3. In another mode, the support structure (e.g., mask table) MT is kept essentially stationary, holding the programmable patterning device, and projects the pattern applied to the radiation beam B onto the target portion C while the substrate table WT is moved or scanned. A pulsed radiation source SO can be used. The programmable patterning device is updated as needed each time the substrate table WT is moved, or between consecutive radiation pulses during scanning. This operating mode is readily available for maskless lithography using programmable patterning devices such as programmable mirror arrays.

[0068]

[0078] Furthermore, combinations and / or variations of the above-mentioned usage modes, or entirely different usage modes, can also be used.

[0069]

[0079] In another embodiment, the lithography apparatus 200 includes an EUV radiation source configured to generate an EUV radiation beam for extreme ultraviolet (EUV) lithography. Generally, the EUV radiation source is configured within a radiation system, and the corresponding illumination system is configured to adjust the EUV radiation beam of the EUV radiation source.

[0070]

[0080] In some embodiments, the lithography apparatus 200' includes a DUV radiation source configured to generate a DUV radiation beam for deep ultraviolet (DUV) lithography. Generally, the DUV radiation source is configured within a radiation system, and the corresponding illumination system is configured to adjust the DUV radiation beam of the DUV radiation source.

[0071]

[0081] Exemplary lithography cell

[0082] Figure 2C shows a lithography cell 202, sometimes called a lithocell or cluster, according to several embodiments. A lithography apparatus 200 or 200' may form part of the lithography cell 200. The lithography cell 202 may also include one or more devices that perform pre-exposure and post-exposure processes on the substrate. Conventionally, these may include a spin coater SC for depositing a resist layer, a developer DE for developing the exposed resist, a cooling plate CH, and a bake plate BK. A substrate handler or robot RO picks up the substrate from input / output ports I / O1 and I / O2, moves them between various process devices, and delivers them to the loading bay LB of the lithography apparatus 200, 200'. These devices are often collectively referred to as a track and are under the control of a track control unit TCU. The TCU itself is controlled by a monitoring and control system SCS. The SCS also controls the lithography apparatus via a lithography control unit LACU. Therefore, these various devices can be operated to maximize throughput and processing efficiency.

[0072]

[0083] Reticle deformation

[0084] Figure 3 shows the deformation of the reticle MA within the reticle clamp 36. The deformation of the reticle MA is minimal at its center. The deformation is maximum at the edge of the reticle in the y-direction 37. In some embodiments, the reticle can be loaded at near ambient temperature, and once imaging of the reticle begins, the outer edge of the reticle expands as this area cools to the operating temperature of the clamp 38, while the imaging area of ​​the reticle expands as the radiated beam heats to the steady-state temperature. The outer edge remains expanded and cold. The further the reticle edge is from the zero-crossing temperature, the greater the distortion in this area of ​​the reticle. This differential distortion causes deformation that cannot be corrected.

[0073]

[0085] Figures 4A and 4B show the deformation of a reticle with a nominally uniform ZCT and a reticle with a secondary ZCT profile in the y-direction. In Figure 4A, reticle 400 has a uniform ZCT profile and / or ZT gradient profile, and the degree of deformation is large at the y-boundary, i.e., at the top and bottom of the grating. Such deformation cannot be corrected by conventional alignment techniques. In such cases, the overlay can be optimized to about 0.5 nm. Figure 4B shows a non-uniform reticle 402 according to this disclosure. The deformation is small at the y-boundary, and the overlay can be optimized to about 0.31 nm.

[0074]

[0086] Figure 5 shows one exemplary embodiment of a reticle 500 according to the present disclosure. The reticle 500 can be a reticle blank. In the schematic diagram shown in Figure 5, the ZCT of the reticle is illustrated such that the minimum ZCT is given in the center of the reticle and the ZCT increases at the -Y and +Y reticle boundaries. Axes of symmetry may exist along both the y-axis and the x-axis.

[0075]

[0087] By providing a non-uniform ZCT profile or ZCT gradient profile to the reticle or reticle blank, the amount of deformation that cannot be corrected during use can be reduced, improving the overlay accuracy of the equipment in which it is used. Traditionally, reticles and reticle blanks were manufactured with the intention of providing a uniform ZCT profile and / or ZCT gradient profile throughout the reticle or reticle blank.

[0076]

[0088] Exemplary reticle stage

[0089] Figures 6 and 7 show a reticle stage 600 according to several embodiments. The reticle stage 600 may include a stage top surface 602, a stage bottom surface 604, a stage side surface 606, and a clamp 700. In some embodiments, the reticle stage 600 including the clamp 700 can be mounted in a lithography apparatus LA. For example, the reticle stage 600 can support a support structure MT within the lithography apparatus LA. In some embodiments, the clamp 700 can be positioned on the stage top surface 602. As shown in Figure 6, the clamp 700 may be positioned in the center of the stage top surface 602 with the clamp front side 702 facing away from the stage top surface 602 in a perpendicular direction.

[0077]

[0090] For example, in some lithography systems such as lithography apparatus LA, a reticle stage 600 including a clamp 700 can be used to hold and position the reticle for scanning or patterning operations. In one example, the reticle stage 600 can utilize a powerful drive, a large balance mass, and a heavy frame to support it. In one example, the reticle stage 600 may have high inertia and weigh more than 500 kg to propel and position a reticle weighing approximately 0.5 kg. To achieve the reciprocating motion of the reticle that is typically performed in lithography scanning or patterning operations, acceleration and deceleration forces can be provided by a linear motor driving the reticle stage 600.

[0078]

[0091] In some embodiments, as shown in Figures 6 and 7, the reticle stage 600 may include a first encoder 612 and a second encoder 614 for positioning operations. For example, the first and second encoders 612 and 614 may be interferometers. The first encoder 612 may be mounted along a first direction, such as the lateral direction (i.e., the X direction) of the reticle stage 600. The second encoder 614 may be mounted along a second direction, such as the longitudinal direction (i.e., the Y direction) of the reticle stage 600. In some embodiments, as shown in Figures 6 and 7, the first encoder 612 may be orthogonal to the second encoder 614.

[0079]

[0092] As shown in Figures 6 and 7, the reticle stage 600 may include a clamp 700. The clamp 700 is configured to hold the reticle 808 on a fixed surface on the reticle stage 600. The clamp 700 includes a clamp front 702 and can be positioned on the stage top surface 602. In some embodiments, the clamp 700 can use mechanical clamping techniques, vacuum clamping techniques, electrostatic clamping techniques, or other suitable clamping techniques to hold and secure the object. In some embodiments, the clamp 700 can be an electrostatic clamp and may be configured to electrostatically clamp (i.e., hold) an object, such as a reticle, in a vacuum environment. In EUV production performed in a vacuum environment, it may be difficult to use a vacuum clamp to clamp a mask or reticle, and instead one or more electrostatic clamps can be used. For example, the clamp 700 may include an electrode, a resistive layer on the electrode, a dielectric layer on the resistive layer, and a bar protruding from the dielectric layer. When in use, a voltage of, for example, several kV can be applied to the clamp 700. As current flows through the resistive layer, the voltage on the upper surface of the resistive layer becomes substantially the same as the voltage at the electrodes, thereby generating an electric field. The Coulomb force, which is the attractive force between particles with electrically opposite charges, attracts the object to the clamp 700 and holds it in place. In some embodiments, the clamp 700 can be made of a rigid material, such as metal, dielectric, ceramic, or a combination thereof.

[0080]

[0093] Exemplary reticle exchange device

[0094] Figures 8 and 9 show a reticle exchange device 801 according to several embodiments. The reticle exchange device 801 may be configured to minimize reticle exchange time, particle generation, and contact force or stress from the clamp 700 and / or reticle 808, thereby reducing damage to the clamp 700 and reticle 808, and increasing the overall throughput of the reticle exchange process, for example, in a lithography apparatus LA.

[0081]

[0095] As shown in Figures 8 and 9, the reticle exchange device 801 may include a reticle stage 600, a clamp 700, and a vacuum robot 800. The vacuum robot 800 may include a reticle handler 802.

[0082]

[0096] In some embodiments, the reticle handler 802 can be a high-speed exchange device (RED) configured to rotate efficiently and minimize reticle exchange time. For example, the reticle handler 802 can save time by moving multiple reticles from one position to another substantially simultaneously rather than sequentially.

[0083]

[0097] In some embodiments, as shown in Figure 8, the reticle handler 802 may include one or more reticle handler arms 804. The reticle handler arms 804 may include a reticle base plate 806. The reticle base plate 806 may be configured to hold an object, for example, a reticle 808.

[0084]

[0098] In some embodiments, the reticle baseplate 806 can be an extreme ultraviolet inner pod (EIP) for the reticle. In some embodiments, the reticle baseplate 806 includes a front side 807 of the reticle baseplate, and the reticle 808 includes a back side 809 of the reticle.

[0085]

[0099] In some embodiments, as shown in Figures 8 and 9, the reticle base plate 806 can hold the reticle 808 such that the front side 807 of the reticle base plate and the back side 809 of the reticle base plate each face the top surface 602 of the stage and the front side 702 of the clamp. For example, the front side 807 of the reticle base plate and the back side 809 of the reticle base plate can face away from the top surface 602 of the stage and the front side 702 of the clamp perpendicularly.

[0086]

[0100] As shown in Figure 9, the reticle exchange device 801 may include a reticle exchange area 810, which is the cross-sectional area between the clamp 700, the reticle 808, the reticle base plate 806, and the reticle handler arm 804 during the reticle exchange process.

[0087]

[0101] In some embodiments, as shown in Figure 8, the reticle handler arms 804 may be arranged symmetrically with respect to the reticle handler 802. For example, the reticle handler arms 804 may be spaced about 90 degrees, 120 degrees, or 180 degrees apart from each other. In some embodiments, the reticle handler arms 804 may be arranged asymmetrically with respect to the reticle handler 802. For example, two reticle handler arms 804 may be spaced about 135 degrees apart from each other, and two other reticle handler arms 804 may be spaced about 90 degrees apart from each other.

[0088]

[0102] In one example, during the reticle exchange process, the reticle handler arm 804 of the reticle handler 802 positions the reticle 808 on the reticle base plate 806 toward the clamp 700 in the reticle exchange area 810. As described above, the transfer of the reticle from the reticle handler 802 to the clamp 700 involves an unknown reticle position offset, which includes a reticle vertical distance offset (i.e., Z-direction offset) and a reticle tilt offset (i.e., R-direction offset). X Offset and R Y This includes offsets. Any tilt or excessive misalignment between the clamp 700 and the reticle 808 can become a source of particles and may damage the reticle 808 or clamp 700 over time. The back side of the reticle 809 and the front side of the clamp 702 can be aligned on the same plane for final delivery. Despite calibration, variations exist due to the mechanical and positioning tolerances of the reticle, which may result in large corner impacts and unpredictable initial contact points between the clamp 700 and the reticle 808.

[0089]

[0103] In one example, the reticle replacement process may include lowering a reticle stage 600, which includes a clamp 700. This may begin away from the reticle handler 802 and approach the reticle 808 until the clamp 700 contacts the reticle 808, thereby accommodating all possible offsets and / or tilts. During the reticle replacement process, the reticle stage 600, including the clamp 700, may be adjusted using multi-stage movement (e.g., a long-stroke stage (coarse movement), a short-stroke stage (fine movement)).

[0090]

[0104] In some embodiments, as shown in Figure 9, the reticle changing device 801 may include a clamp controller 760. The clamp controller 760 may be coupled to the clamp 700 and configured to control the position of the clamp 700. For example, the clamp controller 760 may be configured to control the reticle stage 600 to allow adaptive movement of the clamp 700. In some embodiments, the clamp controller 760 may control the reticle stage 600 and / or the clamp 700 with a servo motor or servo actuator (i.e., X, Y, Z, R) X , R Y , R Z ) can be coupled to the x, y, and z axes (i.e., X direction, Y direction, Z direction), and also to rotations around the x, y, and z axes (i.e., R X , R Y , R Z The translation of the reticle stage 600, including the clamp 700, can be controlled. Here, the x, y, and z axes are Cartesian coordinates.

[0091]

[0105] Reticle thermal distortion

[0106] The thermal strain of the reticle can be modeled as follows.

[0092]

number

[0093] Here, ε is the thermal strain of the reticle, T0 and T f are the initial temperature and the final temperature of the reticle during exposure or during the process, respectively, and CTE(T) is the coefficient of thermal expansion (CTE) of the reticle.

[0094]

[0107] In some embodiments, the reticle can be composed of a material having an appropriate ZCT. For example, the reticle can be composed of ultra-low expansion (ULE) glass. In the case of such a reticle, also, when the temperature variation from the ZCT (denoted as T in the following equation) is small, the CTE of the reticle can be approximated as a linear function of temperature. ZC The CTE can be approximated as a linear function of temperature. CTE = c*(T - T ZC ) Here, c can be determined as a function (or value) by experiment or simulation. Also, it will be understood by those skilled in the art that, without departing from the present invention, in some embodiments, the CTE of the reticle can be approximated even as a non-linear function.

[0095]

[0108] Summarizing the above equations, the thermal strain of the reticle according to some embodiments is given as follows.

[0096]

Equation

[0097]

[0109] Integrating T from T0 to T f up to T gives the following according to the above equation.

[0098]

Equation

[0099] This can be rewritten as follows.

[0100]

Equation

[0101]

[0110] According to the above equation, the thermal strain ε of the reticle along any z-direction is zero under the following two possible conditions:

[0102]

number

[0103]

[0111] The above condition (1) means that the final temperature of the reticle is equal to (or nearly equal to) the initial temperature of the reticle, and therefore the reticle temperature is nearly constant throughout the process. This condition can be applied to inter-wafer effects.

[0104]

[0112] One non-limiting example of the above is when a relatively cold reticle is loaded into the processing unit. During wafer processing, the reticle is exposed to radiation and gradually warms up, with the temperature of the reticle increasing with each subsequent wafer, and finally stabilizing after several wafers. In this example, the thermal strain resulting from such inter-wafer effects on the reticle can be minimized by adjusting the reticle so that its initial and final temperatures are approximately equal, as shown in equation (1) above.

[0105]

[0113] Considering the above, the thermal strain ε of the reticle can be minimized by reducing the difference between the initial and final temperatures of the reticle during processing. This will be referred to below as "reticle adjustment". Those skilled in the art will recognize that the temperature difference can be considered, for example, the spatial average of the reticle temperature or the local temperature profile of the reticle. The following description provides a method and configuration for minimizing the difference between the initial and final temperatures of a reticle, for example, to reduce interwafer thermal strain effects.

[0106]

[0114] Exemplary reticle adjustment

[0115] As described above, one way to minimize the thermal strain ε of the reticle is to adjust the reticle to minimize the difference between its initial temperature and its final temperature (i.e., target operating temperature). Figure 10 shows flowcharts of methods for adjusting the reticle according to several embodiments. In step 1002, the target operating temperature of the reticle in use can be determined. In step 1004, the temperature of the reticle can be controlled to approach the target operating temperature of the reticle determined in step 1002. In step 1006, the reticle can be exposed to radiation to perform the wafer manufacturing process.

[0107]

[0116] Specifically, in step 1002, the target operating temperature of the reticle in use can be determined. The target operating temperature of the reticle can be determined using any convenient method. For example, in some embodiments, the target operating temperature of the reticle can be determined by directly measuring the operating temperature of a precursor reticle or by directly measuring the operating temperature of a reticle during a previous manufacturing process. In some embodiments, the target operating temperature of the reticle can be determined by modeling one or more target operating conditions of the reticle, such as the predicted dose of radiation on the reticle, the approximate absorption pattern of the reticle, the method of holding the reticle, the cooling environment of the reticle, the transmittance of the reticle, and the field size of the exposed reticle.

[0108]

[0117] In step 1004, the reticle temperature can be controlled to approach the target operating temperature of the reticle determined in step 1002. In some embodiments, a model of the reticle using one or more of the above inputs can be used. In some embodiments, reticle temperature calibration can be used. Without departing from the present invention, it will be acknowledged to those skilled in the art that the reticle temperature can be controlled to approach the target operating temperature of the reticle at various points in the wafer process.

[0109]

[0118] In one non-limiting example, according to several embodiments, the temperature of the reticle can be controlled during writing or manufacturing to approach the target operating temperature of the reticle. Thus, the resulting reticle will be closer to the state of a reticle in use.

[0110]

[0119] In another non-limiting example, according to several embodiments, the temperature of a reticle can be controlled to approach its target operating temperature before loading the reticle into the apparatus for manufacturing. In another non-limiting example, the temperature of a reticle can be controlled while it is stored in the internal reticle library (IRL) or while it is being transferred from the IRL to the reticle stage.

[0111]

[0120] As another example, according to several embodiments, after loading the reticle into the apparatus to perform manufacturing, the temperature of the reticle can be controlled to approach the target operating temperature of the reticle while it is being held before the manufacturing process is executed. For example, the temperature of the reticle can be controlled before manufacturing the first wafer in a lot using the reticle. In some embodiments, the reticle may be held in a reticle handler, turret, reticle library, etc.

[0112]

[0121] In some embodiments, after loading the reticle into the apparatus to perform manufacturing, the temperature of the reticle can be controlled to approach the target operating temperature of the reticle while the reticle is held during the execution of the manufacturing process. In some embodiments, the reticle can be mounted on a stage or clamp, and the temperature of the stage or clamp can be controlled based on the target operating temperature of the reticle. In some embodiments, the temperature of the reticle can be controlled during the overhead time between the exposure of two wafers, or during the scanning and / or exposure of the reticle.

[0113]

[0122] In some embodiments, when the temperature of the reticle is controlled during scanning and / or exposure, one or more areas of the reticle are actively heated. According to some embodiments, heat for actively heating the reticle can be supplied, for example, by radiation used in the manufacturing process. Alternatively, heat for actively heating the reticle can be supplied by a source other than radiation used in the manufacturing process, non-limiting examples of which include one or more gas jets, light (e.g., lasers, light-emitting diodes (LEDs), light bulbs, etc.). In some embodiments, the light for heating the reticle may be provided in the form of multiple independently controllable light sources. In one embodiment, the reticle can be heated by multiple lasers scanning the reticle at the start and / or end of the scanning process. In one embodiment, the multiple lasers may constitute, for example, 10 lasers, but the present invention is not limited to this number, and any suitable number of lasers may be used. In one embodiment, the power of each laser can be modulated based on the portion of the reticle that the laser scans.

[0114]

[0123] In some embodiments, heat can be provided by positioning the reticle near a locally heated surface. In some embodiments, the heat provided by positioning near a locally heated surface can be provided in addition to or in place of other heat sources.

[0115]

[0124] In some embodiments, one or more heat sources can be controlled spatially and / or temporally. In some embodiments, one or more heat sources can be controlled using feedforward control based on modeling and prediction, or feedback control based on temperature measurement.

[0116]

[0125] Those skilled in the art will understand that, for example, the thermal loss during reticle loading can be calibrated by measuring the reticle temperature with IRL and then measuring the same reticle temperature after loading it into a reticle handler. In some embodiments, the temperature control of the reticle before loading can be improved by using the thus calibrated thermal loss as feedback in an iterative process that adjusts the temperature control of the reticle, for example.

[0117]

[0126] Figures 11A, 11B, and 11C show non-limiting examples of the configuration of a system for controlling the temperature of a reticle according to several embodiments. According to several embodiments, a system for preconditioning a reticle may include a housing, one or more heating elements, and a controller that uses one or more heating elements to control the temperature of the reticle to a predetermined temperature.

[0118]

[0127] As shown in Figure 11A, in one non-limiting example, the reticle adjustment system includes a housing comprising an IRL 1110. The IRL 1110 may include a number of slots 1112 for holding reticles, a heating layer 1114 for heating reticles, and a slot 1116 for holding reticles that are actively heated by the heating layer 1114.

[0119]

[0128] In another non-limiting example shown in Figure 11B, the reticle adjustment system includes a housing comprising an IRL 1120. The IRL 1120 may include a plurality of slots 1122. A gas jet 1124 supplied from one side of the IRL can provide heat to one or more of the reticles in the slots 1122. One or more temperature sensors 1126 may be provided in the IRL to measure the temperature of one or more reticles in the slots 1122. A controller (not shown) may be connected to the temperature sensors 1126. The controller can control the temperature of one or more reticles to a predetermined temperature before exposing them to radiation to perform a manufacturing process. In some embodiments, the temperature of the reticles can be controlled using temperature control elements. For example, the temperature control elements may include one or more gas jets, light (e.g., laser, light-emitting diode (LED), light bulb, etc.), a hot plate or thermal mass on the image side of the reticle, a cold plate on the clamp side of the reticle, or any other suitable device. In some embodiments, the temperature control element is also mounted using a chuck or clamp, and can be heated and / or cooled when the reticle is supported by this chuck or clamp. In some embodiments, the temperature profile of the temperature control element (e.g., such as a hot plate and / or cold plate) can be spatially varied (e.g., using a Peltier array, a tunable laser, etc.) to fine-tune one or more temperature profiles. For example, the temperature control element can heat and / or cool the reticle outside the area of ​​the reticle that is exposed to radiation.

[0120]

[0129] In some embodiments, a given temperature is the predicted operating temperature of the reticle during exposure to radiation, based on measurement and / or modeling. In some embodiments, the predicted operating temperature can be determined using either the measurement or modeling method described above. In some embodiments, the predicted operating temperature of the reticle during exposure can be based on the predicted dose of radiation from the reticle.

[0121]

[0130] Figure 11C shows another non-limiting example. In this example, the reticle adjustment system includes a housing comprising a reticle handler 1130. The reticle handler 1130 includes a turret 1132 and a heating array 1134 for heating the reticle 1136. In one non-limiting example, the heating array 1134 may constitute an array of infrared (IR) light-emitting diodes (LEDs) that can provide heat to the reticle 1136.

[0122]

[0131] Figure 12A shows the reticle temperature (T) as a function of the number of wafers in a processing lot, according to several embodiments. reticle Figure 12A shows an exemplary measurement. In this exemplary measurement, the reticle temperature may not be adequately controlled to approach the target operating temperature of the reticle in use. Therefore, as shown in Figure 12A, the reticle temperature changes significantly from the first wafer to the fifth wafer. On the other hand, as shown in Figure 12B, the reticle temperature can be precisely controlled to approach the target operating temperature of the reticle in use, according to several embodiments. Therefore, Figure 12B shows that the temperature change of the reticle from the first wafer to the fifth wafer is much smaller than in Figure 12A. Accordingly, the thermal strain on the reticle from the first wafer to the fifth wafer is also much smaller, and as a result, the overlay error is minimized.

[0123]

[0132] Figure 13 shows a flowchart of a method for adjusting the reticle according to several embodiments. In step 1302, the temperature of the chuck or clamp capable of holding the reticle can be measured. In step 1304, the future temperature of the chuck or clamp can be modeled. As a non-limiting example, the future temperature of the chuck or clamp may be affected by factors such as the temperature of the reticle in use, the radiation dose on the reticle, the amount of cooling power supplied to the chuck or clamp, and the material properties of the chuck or clamp and the reticle. In step 1306, the temperature of the chuck or clamp can be controlled. As one non-limiting example, the amount of cooling power supplied to the chuck or clamp can be increased or decreased. As another non-limiting example, the temperature of the chuck or clamp can be controlled to vary spatially. For example, the temperature of the chuck or clamp can be controlled so that the area of ​​the reticle outside the area exposed to radiation is heated and / or cooled. In step 1308, the reticle is exposed to radiation to perform the manufacturing process.

[0124]

[0133] In some embodiments, the method steps in Figure 13 can be performed in addition to, in parallel with, or simultaneously with the method steps in Figure 10. In some embodiments, the method steps in Figure 13 can be performed sequentially with the method steps in Figure 10. As an example, according to some embodiments, the temperature of the chuck or clamp can be controlled according to the method steps in Figure 13 while the temperature of the reticle is being controlled according to the method steps in Figure 10. As another example, according to some embodiments, the temperature of the chuck or clamp can be controlled according to the method steps in Figure 13 before or after performing the method steps in Figure 10 while the temperature of the reticle is being controlled.

[0125]

[0134] The method steps in Figures 10 and 13 can be performed in any possible order, and it is not necessary to perform all steps. Furthermore, the method steps described above only reflect an example of the steps, and are not limiting. That is, other method steps and functions can be conceivable based on the embodiments described above.

[0126]

[0135] Another aspect of the present invention

[0136] In some embodiments, the reticle or reticle blank may include a low-deformation material. In this case, the reticle or reticle blank has a ZCT profile and a ZCT gradient profile, and at least one of the ZCT profile and the ZCT gradient profile is non-uniform. The reticle of the reticle blank may include ultra-low expansion glass. The reticle or reticle blank may have x, y, and z directions, and at least one of the ZCT profile and the ZCT gradient profile varies in the y direction. At least one of the ZCT profile and the ZCT gradient profile may vary in a region adjacent to the edge of the reticle or reticle blank. The ZCT of the reticle or reticle blank may be high at at least one boundary of the reticle or reticle blank. The ZCT of the reticle or reticle blank may have a range of about ±1°C, about ±2°C, about ±3°C, about ±4°C, about ±5°C, about ±6°C, about ±7°C, about ±8°C, about ±9°C, or about ±10°C. The ZCT gradient can be approximately 0.5 ppb / K² to approximately 2.5 ppb / K². The ZCT profile and / or ZCT gradient profile may have at least one axis of symmetry.

[0127]

[0137] In some embodiments, the reticle clamp may include a reticle as described herein. In some embodiments, the lithography apparatus may include a reticle or reticle clamp as described herein.

[0128]

[0138] In some embodiments, a method for mitigating uncorrectable deformation of a reticle or reticle blank may include providing a reticle or reticle blank having at least one of a ZCT profile and a ZCT gradient profile that is non-uniform across the entire reticle or reticle blank. The method may include varying at least one of the ZCT profile and the ZCT gradient profile in regions adjacent to the edges of the reticle or reticle blank. The method may include modeling the deformation of the reticle or reticle blank under operating conditions; calculating the ZCT profile and / or ZCT gradient profile of the reticle or reticle blank to reduce the modeled uncorrectable deformation based on the deformation modeling; optionally repeating these steps until the modeled uncorrectable deformation is reduced to a predetermined level; outputting the optimized ZCT profile and / or ZCT gradient profile of the reticle or reticle blank; and generating a reticle or reticle blank having the optimized ZCT profile and / or ZCT gradient profile.

[0129]

[0139] In some embodiments, the reticle, reticle blank, lithography apparatus, or method described above can be used.

[0130]

[0140] Various embodiments of this system and method are disclosed in the following numbered list of clauses.

[0131] 1. A method for adjusting the reticle, Determining the target operating temperature of the reticle in use, Controlling the reticle temperature to approach the target operating temperature of the reticle in use, Methods that include... 2. The method according to Clause 1, wherein determining the target operating temperature includes directly measuring the operating temperature of the precursor reticle or the reticle used in a previous manufacturing process. 3. The method according to Clause 1, wherein determining the target operating temperature includes modeling one or more target operating conditions of the reticle. 4. The method according to Clause 1, wherein the temperature of the reticle is controlled during writing to approach the target operating temperature of the reticle in use. 5. The temperature of the reticle is controlled before loading the reticle into the apparatus to perform the manufacturing process, as described in Clause 1. 6. The temperature of the reticle is controlled while the reticle is stored in the reticle library, as described in Clause 5. 7. The method of Clause 6, wherein the temperature of the reticle is controlled using a temperature control element while the reticle is stored in the reticle library. 8. The temperature control element includes a gas jet, hot plate, heat mass, or cold plate. The method according to Clause 7, wherein the temperature profile of a hot plate, thermal mass, or cold plate is varied spatially and / or temporally to control the temperature of the reticle while the reticle is stored in the reticle library. 9. The temperature of the reticle is controlled after the reticle has been loaded into the apparatus to carry out the manufacturing process, as described in Clause 1. 10. The temperature of the reticle is controlled while the reticle is held in a reticle handler, turret, or reticle library, as described in Clause 9. 11. The reticle temperature is controlled during the manufacturing process as described in Clause 1. 12. The temperature of the reticle is controlled while the reticle is mounted on the stage or clamp, as described in Clause 11. 13. The reticle temperature is controlled during the overhead time between the exposure of two wafers, as described in Clause 12. 14. The temperature of the reticle is controlled during the scanning and / or exposure of the reticle, as described in Clause 12. 15. The method according to Clause 14, wherein one or more areas of the reticle are actively heated during scanning and / or exposure of the wafer. 16. The method of Clause 15, which includes actively heating one or more areas of the reticle using radiation used in the manufacturing process. 17. The method according to Clause 15, which includes actively heating one or more areas of the reticle using heat supplied from a source other than radiation used in the manufacturing process. 18. Using heat supplied from a source other than radiation used in the manufacturing process, including using a gas jet to heat the reticle, as described in Clause 17. 19. Using heat supplied from a source other than radiation used in the manufacturing process, including the use of light, as described in Clause 17. 20. The method according to Clause 19, wherein the light is provided by one or more of a laser, a light-emitting diode (LED), or a light bulb. 21. The method according to Clause 19, wherein the light is provided by multiple light sources that can be controlled separately. 22. Using heat supplied from a source other than radiation used in the manufacturing process, including using a feedforward-controlled heat source or a feedback-controlled heat source, as described in Clause 17. 23. The method of Clause 17, which involves using heat supplied from a source other than radiation used in the manufacturing process, including placing the reticle near a locally heated surface. 24. The method according to Clause 1, wherein the temperature of the reticle is controlled before the first wafer in the lot is manufactured using the reticle. 25. The method according to Clause 1, further comprising controlling the temperature of a chuck or clamp used to hold a reticle based on the target operating temperature of the reticle. 26. Measure the temperature of the chuck or clamp, Based on the results of temperature measurements of the chuck or clamp, the future temperature of the chuck or clamp is modeled, Based on the modeling of the future temperature of the chuck or clamp, the temperature of the chuck or clamp is controlled, The method described in Article 25, further including the method described in Article 25. 27. Modeling the temperature of the chuck or clamp, Based on the results of temperature measurements of the chuck or clamp, the future temperature of the chuck or clamp is modeled, Based on the modeling of the future temperature of the chuck or clamp, the temperature of the chuck or clamp is controlled, The method described in Article 25, further including the method described in Article 25. 28. Measuring and modeling the temperature of the chuck or clamp, Based on the results of measuring and modeling the temperature of the chuck or clamp, the future temperature of the chuck or clamp will be modeled. Based on the modeling of the future temperature of the chuck or clamp, the temperature of the chuck or clamp is controlled, The method described in Article 25, further including the method described in Article 25. 29. A system for preconditioning the reticle, A housing configured to hold one or more reticles, One or more heating elements configured to heat at least one of the reticles, A controller configured to control the temperature of at least one reticle to a predetermined temperature using one or more heating elements before exposing the reticle to radiation in order to perform a manufacturing process, The given temperature is the predicted operating temperature of the reticle during exposure to radiation for carrying out the manufacturing process. The system predicts the operating temperature of the reticle based on the predicted dose of radiation to the reticle.

[0132]

[0141] The terms “radiation,” “beam,” “light,” and “illumination,” as used herein, can refer to one or more types of electromagnetic radiation, such as ultraviolet (UV) radiation (e.g., with wavelengths λ of 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm), EUV (or soft X-ray) radiation (e.g., with wavelengths in the range of 5 to 100 nm, such as 13.5 nm), or hard X-rays operating at less than 5 nm, and particle beams such as ion beams or electron beams. Generally, radiation with wavelengths of approximately 400 to 700 nm is considered visible radiation. Radiation with wavelengths of approximately 780 to 3000 nm (or above) is considered IR radiation. UV refers to radiation with wavelengths of approximately 100 to 400 nm. In lithography, the term “UV” also applies to wavelengths that can be produced by mercury discharge lamps, namely G-line 436 nm, H-line 405 nm, and / or I-line 365 nm. Vacuum UV, or VUV (i.e., UV absorbed by gas), refers to radiation with wavelengths of approximately 100-200 nm. DUV generally refers to radiation with wavelengths in the range of 126 nm to 428 nm, and in some embodiments, excimer lasers can generate DUV radiation used in lithography equipment. For example, radiation with wavelengths in the range of 5-20 nm can be said to be related to radiation having a specific wavelength band that falls at least part within the range of 5-20 nm.

[0133]

[0142] While some aspects of this disclosure are described in the context of lithography equipment in the manufacture of ICs, it should be understood that the lithography equipment described herein may be used in other applications. Other applications include, for example, the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memory, flat panel displays, LCDs, thin-film magnetic heads, etc. In light of these alternative applications, it will be recognized by those skilled in the art that where the terms “wafer” or “die” are used herein, they may be considered specific examples of the more general terms “substrate” or “target portion,” respectively. The substrate may be processed before or after exposure, for example, with a track unit (usually a tool that coats a layer of resist onto the substrate and develops the exposed resist) and / or a metrology unit. Where appropriate, the aspects disclosed herein may be applied to the above-mentioned and other substrate processing tools. Furthermore, the substrate may be processed multiple times, for example, to produce a multilayer IC, and therefore the term substrate as used herein may also refer to a substrate that already contains multiple processed layers.

[0134]

[0143] Furthermore, while some aspects of this disclosure are described in the context of photolithography, it should be understood that aspects of this disclosure are not limited to photolithography. For example, in imprint lithography, a topography within a patterning device defines the pattern created on the substrate. The topography of the patterning device is imprinted into a resist layer supplied to the substrate, and the resist is cured by applying electromagnetic radiation, heat, pressure, or a combination thereof. The patterning device is removed from the resist, leaving the pattern inside after the resist has cured.

[0135]

[0144] It should be understood that the terms and technical descriptions in this specification are for illustrative purposes only and not for limitation, and therefore, the terms and technical descriptions in this specification should be interpreted by those skilled in the art in light of the teachings contained herein.

[0136]

[0145] The present disclosure has been described above using functional components that exemplify the implementation of specific functions and their relationships. The boundaries of these functional components are arbitrarily defined herein for the sake of explanatory purposes. Alternative boundaries can be defined as long as the specific functions and their relationships are adequately performed. The foregoing descriptions of specific embodiments have sufficiently revealed the overall nature of the present disclosure so that, by applying knowledge of the art, such specific embodiments can be easily modified and / or adapted for various uses without excessive experimentation and without departing from the overall concept of the present disclosure. Accordingly, such adaptations and modifications shall fall within the meaning and scope of equivalents of the disclosed embodiments, based on the teachings and guidance provided herein.

[0137]

[0146] It should be understood that the "Modes for Carrying Out the Invention" section, rather than the "Summary of the Invention" and "Abstract" sections, is intended to be used when interpreting the claims. The "Summary of the Invention" and "Abstract" sections may describe one or more embodiments of the disclosure as envisioned by the inventors, but may not necessarily describe all embodiments, and therefore do not limit the scope of the disclosure and the attached claims in any way. The breadth and scope of the subject matter to be protected is not limited by any of the embodiments described above, but is defined by the following claims and equivalents.

Claims

1. A method for adjusting the reticle, Determining the target operating temperature of the reticle in use, Controlling the temperature of the reticle in use to approach the target operating temperature of the reticle, Methods that include...

2. Determining the target operating temperature is Directly measuring the operating temperature of the precursor reticle or the reticle used in a previous manufacturing process, or Modeling one or more target operating conditions of the aforementioned reticle, The method according to claim 1, including the method described in claim 1.

3. The temperature of the reticle is The reticle is controlled during writing to approach the target operating temperature of the reticle in use, or Controlled before loading the reticle into the apparatus in order to perform the manufacturing process, The method according to claim 1.

4. The temperature of the reticle is controlled while the reticle is stored in the reticle library. While the reticle is stored in the reticle library, the temperature of the reticle is controlled using a temperature control element. The temperature control element includes a gas jet, a hot plate, a heat mass, or a cold plate. The method according to claim 3, wherein the temperature profiles of the hot plate, the thermal mass, or the cold plate are varied spatially and / or temporally to control the temperature of the reticle while the reticle is stored in the reticle library.

5. The temperature of the reticle is controlled after the reticle has been loaded into the apparatus to perform the manufacturing process. The method according to claim 1, wherein the temperature of the reticle is controlled while the reticle is held in a reticle handler, turret, or reticle library.

6. The temperature of the reticle is controlled during the manufacturing process. The temperature of the reticle is controlled while the reticle is mounted on a stage or clamp. The temperature of the reticle is controlled during the overhead time between the exposure of two wafers, or The method according to claim 1, wherein the temperature of the reticle is controlled during scanning and / or exposure of the reticle.

7. The method according to claim 6, wherein one or more areas of the reticle are actively heated during scanning and / or exposure of the wafer.

8. The method according to claim 7, wherein the active heating of one or more areas of the reticle includes heating the reticle using the radiation used in the manufacturing process.

9. Actively heating one or more areas of the reticle includes heating the reticle using heat supplied from a source other than radiation used in the manufacturing process, Using heat supplied from a source other than the radiation used in the manufacturing process is, A gas jet is used to heat the reticle. Using light provided by one or more light sources, such as lasers, light-emitting diodes (LEDs), or light bulbs, or by multiple light sources that can be controlled separately. Using a feedforward-controlled or feedback-controlled heat source, The reticle is positioned near a locally heated surface. The method according to claim 7, including the method described in claim 7.

10. The method according to claim 1, wherein the temperature of the reticle is controlled before the first wafer in a lot is manufactured using the reticle.

11. The method according to claim 1, further comprising controlling the temperature of a chuck or clamp used to hold the reticle based on the target operating temperature of the reticle.

12. Measuring the temperature of the chuck or clamp, Based on the measurement results of the temperature of the chuck or clamp, the future temperature of the chuck or clamp is modeled. Controlling the temperature of the chuck or clamp based on the modeling of the future temperature of the chuck or clamp, The method according to claim 10, further comprising:

13. Modeling the temperature of the chuck or clamp, Based on the measurement results of the temperature of the chuck or clamp, the future temperature of the chuck or clamp is modeled. Controlling the temperature of the chuck or clamp based on the modeling of the future temperature of the chuck or clamp, The method according to claim 10, further comprising:

14. Measuring and modeling the temperature of the chuck or clamp, Based on the results of the measurement and modeling of the temperature of the chuck or clamp, the future temperature of the chuck or clamp is modeled. Controlling the temperature of the chuck or clamp based on the modeling of the future temperature of the chuck or clamp, The method according to claim 10, further comprising:

15. A system for preconditioning the reticle, A housing configured to hold one or more reticles, One or more heating elements configured to heat at least one of the one or more reticles, A controller configured to control the temperature of at least one of the reticles to a predetermined temperature using one or more heating elements before exposing the reticle to radiation in order to perform a manufacturing process, The predetermined temperature is the predicted operating temperature of the reticle during exposure to the radiation for performing the manufacturing process. The predicted operating temperature of the reticle is based on the predicted dose of radiation to the reticle, according to the system.

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