Method and system for determining reticle deformation

Abstract

The present specification discloses a computer system configured to model the shape and / or deformation of a reticle and control the operation of a lithography process using the reticle depending on the modeled shape and / or deformation, wherein to model the shape and / or deformation of the reticle, the computer system is configured to acquire initial reference shape data representing the shape of the reticle, acquire reticle heating calibration (RHC) data including reticle shape data at different reticle temperatures and corresponding reticle alignment (RA) measurement data, generate calibrated reference shape data depending on the initial reference shape data, the RHC data, and the RA measurements, and model the shape and / or deformation of the reticle depending on the calibrated reference shape data.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to EP application EP22216576.3, filed December 23, 2022, which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates to techniques for improving the accuracy of determining deformations of a reticle, depending on which process modifications may be determined and applied to reduce reticle-induced errors in a lithography process. [Background technology]

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

[0004]

[0004] Lithographic apparatus may use electromagnetic radiation to project a pattern onto a substrate. The wavelength of this radiation determines the minimum size of features that can be formed on the substrate. Lithographic apparatus using extreme ultraviolet (EUV) radiation, having a wavelength in the range of 4 to 20 nm, e.g., 6.7 nm or 13.5 nm, may be used to form smaller features on a substrate than lithographic apparatus using deep ultraviolet (DUV) radiation, e.g., having a wavelength of 157 nm, 193 nm, or 248 nm.

[0005] A lithographic apparatus may include a reticle stage to hold a patterning device (e.g., a reticle) for transferring a pattern onto a substrate. Heating and / or cooling of the reticle may cause changes in reticle properties that may affect the path (e.g., focus) of a radiation beam and result in distortions (e.g., overlay errors) on the patterned substrate. The changes in reticle properties can be modeled and corrected using a reticle heating model. Known reticle heating models rely on a sensor-based approach that uses a reticle temperature sensor (RTS) to calibrate the reticle heating model and require a calibration lot of product wafers. In some instances, this approach may be inaccurate and inefficient because the RTS may exhibit errors, causing unnecessary delays and requiring rework of the product wafers.

[0006]

[0006] The shape of the reticle may also be deformed by other influences, such as clamping forces applied to the reticle, all of which may increase distortions (e.g., overlay errors) in the patterned substrate if not addressed. Summary of the Invention

[0007] There is a general need to improve known techniques for determining deformations in reticle features. Depending on the determined deformations, process modifications may be determined and applied to reduce reticle-induced errors in a lithography process. This may avoid reworking of product substrates and / or increase manufacturing throughput and yield of the lithography process.

[0008]

[0008] According to a first aspect of the present invention, there is provided a computer system configured to model the shape and / or deformation of a reticle and control the operation of a lithography process using the reticle in dependence on the modeled shape and / or deformation, wherein, in order to model the shape and / or deformation of the reticle, the computer system is configured to acquire initial reference shape data representing the shape of the reticle, acquire reticle heating calibration (RHC) data including reticle shape data at different reticle temperatures and corresponding reticle alignment (RA) measurement data, generate calibrated reference shape data in dependence on the initial reference shape data, the RHC data and the RA measurement, and model the shape and / or deformation of the reticle in dependence on the calibrated reference shape data.

[0009]

[0009] According to a second aspect of the present invention, there is provided a method comprising modeling the shape and / or deformation of a reticle and controlling the operation of a lithography process using the reticle depending on the modeled shape and / or deformation, wherein modeling the shape and / or deformation of the reticle comprises obtaining initial reference shape data representing the shape of the reticle, obtaining reticle heating calibration (RHC) data including reticle shape data at different reticle temperatures and corresponding reticle alignment (RA) measurement data, generating calibrated reference shape data depending on the initial reference shape data, the RHC data and the RA measurements, and modeling the shape and / or deformation of the reticle depending on the calibrated reference shape data.

[0010]

[0010] According to a third aspect of the present invention, there is provided a system comprising a computer system according to the first aspect and a lithographic apparatus, wherein the computer system is configured to control the operation of the lithographic apparatus.

[0011] According to a fourth aspect of the present invention, there is provided a device manufacturing method using a lithography process, the device manufacturing method including the method according to the second aspect.

[0012] According to a fifth aspect of the present invention, there is provided a non-transitory computer readable medium program comprising computer readable instructions configured to cause a processor to control a lithographic apparatus according to the method of the second aspect.

[0013]

[0013] Implementations of any of the above technologies may include EUV light sources, DUV light sources, systems, methods, processes, devices, and / or apparatus. Details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.

[0014]

[0014] Further features and exemplary aspects of the embodiments, together with the structure and operation of various embodiments, will be described in detail below with reference to the accompanying drawings. It should be noted that the embodiments are not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to those skilled in the art based on the teachings contained herein. [Brief explanation of the drawings]

[0015]

[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments and, together with the description, serve to explain the principles of the embodiments and enable those skilled in the art to make and use the embodiments.

[0016] [Figure 1]

[0016] FIG. 1 is a schematic diagram of a lithographic apparatus according to an exemplary embodiment. [Figure 2A]

[0017] FIG. 1 is a schematic diagram of a lithographic cell according to an exemplary embodiment. [Figure 2B]

[0018] FIG. 1 is a schematic diagram of an integrated lithography system including a computer system for optimizing a lithography process, according to an exemplary embodiment. [Figure 3A]

[0019] FIG. 2 is a schematic bottom perspective view of a reticle stage and a reticle according to an exemplary embodiment. [Figure 3B]

[0020] FIG. 3B is a schematic bottom view of the reticle stage shown in FIG. 3A. [Figure 4A]

[0021] 1 is a schematic top perspective view of a reticle exchange apparatus according to an exemplary embodiment; [Figure 4B]

[0022] 4B is a schematic partial cross-sectional view of the reticle exchange device shown in FIG. 4A. [Figure 5]

[0023] 1 is a schematic diagram of a reticle calibration method according to an exemplary embodiment. [Figure 6]

[0023] FIG. 1 is a schematic diagram of a reticle calibration method according to an exemplary embodiment. [Figure 7]

[0024] FIG. 7 is a schematic diagram of k parameters for the reticle calibration method shown in FIGS. 5 and 6, according to an exemplary embodiment. [Figure 8] FIG. 7 is a schematic diagram of k parameters for the reticle calibration method shown in FIGS. 5 and 6, according to an exemplary embodiment. [Figure 9]

[0025] 1 illustrates a reticle calibration diagram according to an exemplary embodiment. [Figure 10]

[0025] A reticle calibration diagram according to an exemplary embodiment is shown. [Figure 11]

[0026] 1 shows a deterministic reticle heating model. [Figure 12]

[0027] 3 illustrates a deterministic reticle heating model according to a first embodiment. [Figure 13]

[0028] 10 shows the difference in modeled ratio of overlay to reticle temperature as a lot of substrates is processed for both the known model and the model according to the first embodiment. [Figure 14]

[0029] 10A and 10B show schematic diagrams of overlay error that can be caused by reticle temperature if no process is performed that corrects the cause of the overlay error. [Figure 15]

[0030] 1 illustrates a method for obtaining RA measurements for a process performed on a first substrate of a lot of substrates, according to known techniques. [Figure 16]

[0031] 1 illustrates a method for obtaining RA measurements for a process performed on a lot of substrates, according to known techniques. [Figure 17]

[0032] 10 illustrates a technique for obtaining RA measurements for a process performed on a lot of substrates, according to a fourth embodiment. [Figure 18]

[0033] 3 is a flowchart of a process according to the first embodiment. [Figure 19]

[0034] 10 is a flowchart of a process according to a second embodiment. [Figure 20]

[0035] 10 is a flowchart of a process according to a third embodiment. [Figure 21]

[0036] 10 is a flowchart of a process according to a fourth embodiment. [Figure 22]

[0037] 10 is a flowchart of a process according to a fifth embodiment.

[0017]

[0038] Features and example aspects of the embodiments will become more apparent from the detailed description set forth below when considered in conjunction with the drawings, in which like reference numerals identify corresponding elements throughout. In the drawings, like reference numerals generally indicate identical, functionally similar, and / or structurally similar elements. Also, the left-most digit(s) of a reference number generally identifies the drawing in which that reference number first appears. The drawings provided throughout this disclosure should not be construed as drawings to scale unless otherwise indicated. DETAILED DESCRIPTION OF THE INVENTION

[0018]

[0039] This specification discloses one or more embodiments incorporating features of the present invention. The disclosed embodiments are merely exemplary of the present invention. The scope of the present invention is not limited to the disclosed embodiments. The present invention is defined by the claims appended hereto.

[0019]

[0040] References to the described embodiments, and to "one embodiment," "an embodiment," "example embodiment," "exemplary embodiment," and the like, herein indicate that the described embodiment may include a particular feature, structure, or property, but not all embodiments necessarily include such a particular feature, structure, or property. Furthermore, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or property is described in connection with one embodiment, it is understood that it is within the knowledge of one of ordinary skill in the art to implement such feature, structure, or property in connection with other embodiments, whether expressly stated or not.

[0020]

[0041] Spatially relative terms such as "below," "below," "lower," "above," "on," "higher," and the like may be used herein for ease of description to describe the relationship of one element or feature to another element or feature, as shown in the figures. Spatially relative terms are intended to encompass various orientations of the device in use or operation in addition to the orientation shown in the figures. The device may be oriented differently (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein may be similarly interpreted accordingly.

[0021]

[0042] As used herein, the terms "about" or "substantially" or "approximately" refer to a given quantity value that may vary based on a particular technique. Based on a particular technique, the terms "about" or "substantially" or "approximately" may refer to a given quantity value that varies, for example, within 1-15% of the value (e.g., ±1%, ±2%, ±5%, ±10%, or ±15% of the value).

[0022]

[0043] As used herein, the term "parasitic thermal effects" refers to induced or internal stresses and / or deformations of a reticle resulting from, for example, heating and / or cooling the reticle (e.g., by resistive heating, gas flow cooling, exposing the reticle to a radiation dose, etc.) or mechanical pressure, and / or deformations of the reticle resulting from clamping and / or holding the reticle on a reticle stage.

[0023]

[0044] As used herein, the term "non-production substrate" refers to a substrate (e.g., a wafer) that is not part of a production lot and that is not fabricated into a device (e.g., an IC chip) by a lithography process. For example, a non-production substrate may be a chuck temperature control (CTC) wafer or a calibration wafer for a reticle calibration method that adapts a reticle by, for example, calibrating a reticle heating model, exposing the reticle and CTC wafer to a radiation dose, and measuring reticle alignment and / or reticle temperature.

[0024]

[0045] As used herein, the term "production substrate" refers to a substrate (e.g., a wafer) that is part of a production lot and that is fabricated into devices (e.g., IC chips) by a lithographic process. For example, a product substrate can be a wafer (e.g., silicon) for production or a wafer (e.g., silicon) for in-line real-time calibration of a reticle heating model, for example, by exposing a reticle and wafer to a radiation dose and measuring reticle alignment and / or reticle temperature.

[0025]

[0046] As used herein, the term "reticle heating model" refers to reticle alignment and / or reticle shape deformation, and a modal deformation approach (e.g., analysis of different reticle mode shapes) for determining reticle heating effects based on a finite element model (FEM) (e.g., COMSOL). For example, the reticle heating model can be deterministic (e.g., no random future states) or non-deterministic (e.g., including random future states) reticle heating effects. Furthermore, the reticle heating model can be considered a reticle heating execution algorithm (RHEA) that determines baseline reticle heating dynamics using in-line modal calibration. The reticle heating model can be calibrated by exposing a reticle and a non-product substrate to a radiation dose for in-line real-time calibration of the reticle heating model. In some aspects, the reticle heating model can be calibrated, for example, by exposing a reticle and a product substrate to a radiation dose for in-line real-time calibration of the reticle heating model. Other reticle heating models utilize sensor-based approaches (e.g., using RTS measurements) to calibrate the reticle heating model, as described in more detail in U.S. Pat. Nos. 10,429,749, 10,281,825, and U.S. Publication No. 2020 / 0166854, which are incorporated by reference in their entireties.

[0026]

[0047] Reticle heating affects the radiation path and causes changes in reticle properties that can result in manufacturing errors (e.g., overlay). Mechanical deformation of the reticle (e.g., based on reticle temperature) can be calculated and decomposed into k-parameters. Each thermomechanical mode (e.g., eigenvector) can be modeled in time using a modal contribution coefficient μ and a time constant τ. Measured overlay and / or alignment can be used to model drift in the associated k-parameter, which can be used to calculate adjustments to the feedforward parameters μ and τ. The reticle heating model can also include adjusting the feedforward parameters μ and τ. This is described in more detail in U.S. Pat. No. 10,429,749, U.S. Publication No. 2020 / 0166854, and WIPO Publication No. 2021 / 043519, which are incorporated herein by reference in their entireties.

[0027]

[0048] As used herein, the term "finite element model" or "FEM" refers to a method for numerically solving differential equations (e.g., heat conduction equations, structural analysis equations, fluid flow equations, etc.) that arise in a reticle heating model. For example, baseline reticle heating dynamics may be analyzed by FEM through finite element analysis, as described in more detail in U.S. Pat. Nos. 10,429,749, 10,281,825, and U.S. Publication No. 2020 / 0166854, which are incorporated by reference in their entireties.

[0028]

[0049] As used herein, the terms "key performance metrics" or "KPIs" or "k parameters" refer to the coefficients of a polynomial that is fitted to the distortions of the reticle alignment marks and / or edge alignment marks. The k parameters parameterize the distortion of the imaging across the field of each substrate. For example, each k parameter can represent a specific image distortion component (e.g., scaling error, barrel distortion, pincushion distortion, etc.). For example, two important k parameters are k4 (e.g., k4 / my shown in FIG. 7 ), which represents the Y-axis magnification distortion, and k18 (e.g., k18 / cshpy shown in FIG. 8 ), which represents the Y-axis barrel distortion. The k parameters can be used as inputs to the lithography process (e.g., lithography apparatus LA, lithographic cell LC, control system CL) to correct for the distortions. This is described in further detail in U.S. Patent No. 10,429,749, U.S. Publication No. 2020 / 0166854, and WIPO Publication No. 2021 / 043519, which are incorporated by reference herein in their entireties.

[0029]

[0050] As used herein, the term "in-line real-time calibration" refers to calibration of a reticle heating model during actual production of product substrates. For example, calibration lots of product substrates may be avoided, and rework of product substrates for calibration purposes may be reduced or avoided. Calibration may be performed in-line by exposing the reticle and product substrate to a radiation dose. Furthermore, calibration may be performed in real time (e.g., at a real-time frame rate or at a computation speed of 2.56 seconds or less).

[0030]

[0051] Aspects of the present disclosure may be implemented in hardware, firmware, software, or any combination thereof. Aspects of the present disclosure may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, electrical, optical, acoustic, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and the like. Furthermore, firmware, software, routines, and / or instructions may be described herein as performing certain operations. However, it should be understood that such description is merely for convenience and that such operations actually result from a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc.

[0031]

[0052] However, before describing such aspects in more detail, it is helpful to present an exemplary environment in which aspects of the present disclosure may be implemented.

[0032]

[0053] Exemplary Lithography System

[0033]

[0054] 1 shows a lithography system comprising a radiation source SO and a lithography apparatus LA. The radiation source SO is configured to generate a beam of EUV and / or DUV radiation B and to provide the beam of EUV and / or DUV radiation B to the lithography apparatus LA. The lithography apparatus LA comprises an illumination system IL, a support structure MT (e.g. a mask table, reticle table, reticle stage) configured to support a patterning device MA (e.g. a mask, reticle), a projection system PS, and a substrate table WT configured to support a substrate W.

[0034]

[0055] The illumination system IL is configured to condition the EUV and / or DUV radiation beam B before it is incident on the patterning device MA. To that end, the illumination system IL may include a facetted field mirror device 10 and a facetted pupil mirror device 11. Together, the facetted field mirror device 10 and the facetted pupil mirror device 11 impart a desired cross-sectional shape and a desired intensity distribution to the EUV and / or DUV radiation beam B. The illumination system IL may include other mirrors or devices in addition to or instead of the facetted field mirror device 10 and the facetted pupil mirror device 11.

[0035]

[0056] After being so conditioned, the EUV and / or DUV radiation beam B interacts with the patterning device MA. This interaction may be reflective (as shown), which may be favorable for EUV radiation. This interaction may be transmissive, which may be favorable for DUV radiation. As a result of this interaction, a patterned EUV and / or DUV radiation beam B' is produced. The projection system PS is configured to project the patterned EUV and / or DUV radiation beam B' onto the substrate W. To that end, the projection system PS may comprise a plurality of mirrors 13, 14 configured to project the patterned EUV and / or DUV radiation beam B' onto the substrate W held by a substrate table WT. The projection system PS may apply a demagnification factor to the patterned EUV and / or DUV radiation beam B' to thereby form images of features that are smaller than corresponding features on the patterning device MA. For example, a demagnification factor of 4 or 8 may be applied. Although the projection system PS is shown in Figure 1 as having only two mirrors 13, 14, the projection system PS may include a different number of mirrors (for example six or eight mirrors).

[0036]

[0057] The substrate W may include a pre-formed pattern, in which case the lithographic apparatus LA aligns the image formed by the patterned EUV and / or DUV radiation beam B' with the pre-formed pattern on the substrate W.

[0037]

[0058] Exemplary Lithographic Cell

[0038]

[0059] FIG. 2A shows a lithographic cell LC, sometimes referred to as a lithocell or cluster. A lithographic apparatus LA may form part of the lithographic cell LC. The lithographic cell LC may also include one or more devices for performing pre-exposure and post-exposure processes on a substrate. These conventionally include a spin coater SC for depositing a resist layer, a developer DE for developing the exposed resist, a chill plate CH, and a bake plate BK. A substrate handler or robot RO retrieves substrates from input / output ports I / O1 and I / O2, moves the substrates between different processing equipment, and delivers the substrates to the loading bay LB of the lithographic apparatus LA. These devices, often collectively referred to as the track, are under the control of a track control unit TCU, which itself is controlled by a supervisory control system SCS, which also controls the lithographic apparatus LA via a lithography control unit LACU. In this way, the different devices can be operated to maximize throughput and processing efficiency.

[0039]

[0060] To ensure that a substrate W to be exposed by the lithographic apparatus LA is exposed correctly and consistently, it is desirable to inspect the substrate to measure properties of the patterned substrate, such as overlay error between subsequent layers, line thickness, critical dimension (CD), etc. For this purpose, an inspection tool (e.g., metrology tool MT) may be included in the lithographic cell LC and / or the lithographic apparatus LA. If an error is detected, adjustments may be made, for example, to the exposure of a subsequent substrate or other processing step to be performed on the substrate W, particularly if inspection is performed before other substrates W of the same batch or lot are subsequently exposed or processed.

[0040]

[0061] The inspection apparatus, which may also be referred to as a metrology apparatus or metrology tool MT, is used to determine the properties of the substrate W, in particular how the properties of different substrates W vary, or how properties associated with different layers of the same substrate W vary from layer to layer. The inspection apparatus may alternatively be constructed to identify defects on the substrate W and may, for example, be part of a lithographic cell LC, integrated into the lithographic apparatus LA, and / or be a stand-alone device. The inspection apparatus may measure properties related to the latent image (e.g., an image in the resist layer after exposure), the semi-latent image (e.g., an image in the resist layer after a post-exposure bake step), the developed resist image (e.g., an image where exposed or unexposed portions of the resist have been removed), or the etched image (e.g., an image after a pattern transfer step such as etching).

[0041]

[0062] Exemplary Computer System

[0042]

[0063] FIG. 2B illustrates a computer system CL, also referred to as a controller or processor. The computer system CL may be integrated into a lithography apparatus LA, be part of a lithography cell LC, and / or be a stand-alone device. The computer system CL is configured to optimize the lithography process, for example, to calibrate a reticle heating model. The patterning process in a lithography apparatus LA is typically one of the most critical steps in processing, requiring high accuracy in the dimensioning and placement of structures on a substrate W. To ensure this high accuracy, three systems can be combined in a so-called “integrated” control environment, as schematically illustrated in FIG. 2B. As illustrated in FIG. 2B, the “integrated” environment may include a lithography apparatus LA, a computer system CL, and a metrology tool MT. For example, the lithography apparatus LA (first system) may be connected to the computer system CL (second system) and the metrology tool MT (third system).

[0043]

[0064] The key to such integrated lithography is optimizing the coordination between these three systems to optimize the lithography process, e.g., by enforcing the overall process window and providing a tight control loop to ensure that the patterning performed by the lithography apparatus LA stays within the process window. A process window defines the range of process parameters, e.g., dose, focus, overlay, etc., within which a particular manufacturing process is defined to result in, e.g., a functional semiconductor device, and is typically the range within which process parameters in the lithography or patterning process are allowed to vary.

[0044]

[0065] The computer system CL may, for example, use the design layout (e.g., a portion thereof) to be patterned to predict which resolution enhancement techniques should be used and perform computational lithography simulations and calculations to determine mask layouts and lithography apparatus settings that maximize the overall process window of the patterning process (indicated by the double-headed arrow at the first scale SC1 in FIG. 2B). Typically, the resolution enhancement techniques are configured to match the patterning capabilities of the lithography apparatus LA. The computer system CL may also be used to detect where within the process window the lithography apparatus LA is currently operating (e.g., using input from the metrology tool MT) to predict whether defects due to suboptimal processing may exist (indicated by the arrow pointing to "0" at the second scale SC2 in FIG. 2B).

[0045]

[0066] The metrology tool MT may provide input to the computer system CL, for example, enabling accurate simulations and predictions. For example, the metrology tool MT may provide alignment information. The metrology tool MT may provide feedback to the lithography apparatus LA (e.g., via the computer system CL) to identify possible drifts in the calibration status of the lithography apparatus LA, for example (as indicated by multiple arrows at the third scale SC3 in FIG. 2B). In a lithography process, it is desirable to frequently measure the structures being created, for example, for process control and verification. Different types of metrology tools MT may be used to measure one or more characteristics related to, for example, the lithography apparatus LA, the patterned substrate W, and / or reticle alignment. This is described in more detail in U.S. Pat. No. 11,099,319 and WIPO Publication No. 2021 / 043519, which are incorporated herein by reference in their entireties.

[0046]

[0067] Exemplary Reticle Stage and Reticle

[0047]

[0068] 3A and 3B show schematic diagrams of an example embodiment of a reticle stage 200. Fig. 3A is a schematic bottom perspective view of the reticle stage 200 and a reticle 300 according to an example embodiment. Fig. 3B is a schematic bottom view of the reticle stage 200 and a reticle 300 shown in Fig. 3A.

[0048]

[0069] Reticle stage 200 (e.g., support structure MT) can be used in a lithographic apparatus (e.g., lithographic apparatus LA) to hold a patterning device (e.g., patterning device MA). Reticle stage 200 can include a bottom stage surface 202, a top stage surface 204, a side stage surface 206, clamps 250, a reticle cage 224, and / or a reticle 300. In some embodiments, reticle stage 200 with reticle 300 can be implemented in lithographic apparatus LA. For example, reticle stage 200 can be a support structure MT in lithographic apparatus LA. In some embodiments, reticle 300 can be disposed on bottom stage surface 202 and held by clamps 250. 3A and 3B, the reticle 300 can be disposed on a clamp 250 (e.g., an electrostatic clamp) at the center of the bottom stage surface 202 with the front side 302 of the reticle facing vertically away from the bottom stage surface 202. In some embodiments, a reticle cage 224 can be disposed on the bottom stage surface 202. For example, as shown in FIGS. 3A and 3B, the reticle 300 can be disposed at the center of the bottom stage surface 202 and secured by a reticle cage 224 adjacent each corner of the reticle 300.

[0049]

[0070] In some lithography apparatuses, such as lithography apparatus LA, a reticle stage 200 having clamps 250 can be used to hold and position a reticle 300 for scanning or patterning operations. In some embodiments, as shown in FIGS. 3A and 3B , the reticle stage 200 can include a first encoder 212 and a second encoder 214 for positioning operations. For example, the first and second encoders 212 and 214 can be interferometers. The first encoder 212 can be attached to the reticle stage 200 along a first direction, such as the horizontal direction (i.e., the X direction). The second encoder 214 can be attached to the reticle stage 200 along a second direction, such as the vertical direction (i.e., the Y direction).

[0050]

[0071] As shown in FIGS. 3A and 3B, the reticle 300 may include a reticle front side 302, alignment marks 310, and / or edge alignment marks 320. The alignment marks 310 are configured to measure reticle alignment between the reticle 300 and a substrate (e.g., substrate W, non-production substrate, or production substrate). In some embodiments, as shown in FIGS. 3A and 3B, one or more alignment marks 310 may be disposed at the corners and / or center of the reticle 300 for RA measurements. The edge alignment marks 320 are configured to measure reticle shape deformation of the reticle 300 due to thermal expansion when the reticle 300 is not within a predetermined temperature range (e.g., 22° C.±0.2° C.). In some embodiments, as shown in FIGS. 3A and 3B, one or more edge alignment marks 320 may be disposed along the peripheral edges (e.g., horizontal and vertical edges) of the reticle 300 for reticle shape deformation (RSD) measurements. In some embodiments, the results of the RA and / or RSD measurements can be converted to reticle temperatures, for example, by FEM, which determines the temperatures based on reticle alignment and / or reticle deformation.

[0051]

[0072] Exemplary Reticle Exchange Apparatus

[0052]

[0073] 4A and 4B show schematic views of an exemplary embodiment of a reticle exchange apparatus 100. Fig. 4A is a schematic top perspective view of the exemplary embodiment of the reticle exchange apparatus 100. Fig. 4B is a schematic partial cross-sectional view of the reticle exchange apparatus 100 shown in Fig. 4A.

[0053]

[0074] The reticle exchange apparatus 100 can be configured to reduce reticle exchange time and thermal stress in the reticle 300, for example, to increase overall throughput in the lithography apparatus LA. In some aspects, the reticle exchange apparatus 100 can reduce stress in the reticle 300 by transferring the reticle 300 from the reticle stage 200 to an in-vacuum robot (IVR) 400. For example, the reticle exchange apparatus 100 can quickly unclamp the reticle 300 from the reticle cage 224 and clamps 250 and transfer the reticle 300 to the IVR 400 to relieve thermal stress in the reticle 300. In some embodiments, reticle exchange apparatus 100 can reduce stress on reticle 300 and increase throughput by unclamping reticle 300, transferring reticle 300 from reticle stage 200 to IVR 400, and quickly returning and clamping reticle 300 to reticle stage 200. As shown in FIGS. 4A and 4B, reticle exchange apparatus 100 can include reticle stage 200, clamp 250, and IVR 400.

[0054]

[0075] The IVR 400 may include a reticle handler 402 having one or more reticle handler arms 404. In some embodiments, the reticle handler 402 may be a rapid exchange device (RED) configured to efficiently rotate and minimize reticle exchange time. The reticle handler arm 404 may include a reticle base plate 406 configured to hold an object, such as a reticle 300. In some embodiments, the reticle base plate 406 may be an extreme ultraviolet internal pod (EIP) for the reticle 300. The reticle base plate 406 includes a reticle base plate front side 407, and the reticle 300 includes a reticle back side 304.

[0055]

[0076] 4A and 4B, the reticle base plate 406 can hold the reticle 300 such that the reticle base plate front side 407 and the reticle back side 304 face the bottom stage surface 202 and the clamp front side 252, respectively. For example, the reticle base plate front side 407 and the reticle back side 304 can face perpendicularly away from the bottom stage surface 202 and the clamp front side 252. As shown in FIG. 4B, the reticle exchange apparatus 100 can include a reticle exchange area 410, which is a cross-sectional area between the clamp 250, the reticle 300, the reticle base plate 406, and the reticle handler arm 404 during the reticle exchange process.

[0056]

[0077] In one example, during a reticle exchange process, reticle handler arm 404 of reticle handler 402 positions reticle 300 on reticle base plate 406 toward clamps 250 in reticle exchange area 410. As described above, handing off the reticle from reticle handler 402 to clamps 250 and vice versa can relieve thermal stresses in reticle 300 and reduce parasitic thermal effects in reticle 300.

[0057]

[0078] Exemplary Reticle Calibration Method

[0058]

[0079] As discussed above, a lithographic apparatus (e.g., lithographic apparatus LA) may include a reticle stage (e.g., support structure MT, reticle stage 200) for holding a patterning device (e.g., patterning device MA, reticle 300) for transferring a pattern onto a substrate (e.g., substrate W). Heating and / or cooling of the reticle can cause changes in reticle properties that can affect the path (e.g., focus) of the radiation beam and result in distortions (e.g., overlay errors) in the patterned substrate. The changes in reticle properties can be modeled and corrected using a reticle heating model. Current reticle heating models rely on sensor-based, application-specific approaches that use an RTS to calibrate the reticle heating model and require a calibration lot of production wafers.

[0059]

[0080] In some instances, this approach can be inaccurate and inefficient because the RTS may exhibit errors, causing unnecessary delays and requiring rework of product wafers. In some embodiments, the RTS has a temperature gradient variation of approximately ±0.6°C, which can cause overlay mismatch of approximately 1 nm / °C. Also, in some embodiments, reticle temperature measurement using the RTS can require approximately 5 seconds per wafer, resulting in additional delays. Furthermore, in some embodiments, preconditioning reticles in an internal reticle library (IRL) can require additional time to adjust (e.g., cool) the reticles to the desired temperature (e.g., 22°C ±0.2°C), and some reticles may be retained in the IRL longer than necessary. For example, preconditioning delays can cause delays of up to 7 minutes each time, potentially resulting in production loss of up to 35 product wafers per occurrence. Additionally, changes in the thermo-mechanical properties of the reticle prior to calibration can amplify and worsen overlay mismatch (e.g., increasing from 1 nm / °C to over 2.1 nm / °C). Additionally, product wafers used for calibration may be reworked over time, which can introduce additional delays and reduce overall throughput.

[0060]

[0081] Aspects of the reticle calibration apparatus, systems and methods discussed below may increase the calibration accuracy and speed of reticle heating models, reduce reticle adjustment time, reduce stress in the reticle, avoid reworking of product substrates, and / or increase manufacturing throughput and yield of the lithography process.

[0061]

[0082] 5-8 illustrate reticle calibration methods 500, 600 according to various exemplary embodiments. FIG. 5 is a schematic diagram of reticle calibration method 500 according to an exemplary embodiment. FIG. 6 is a schematic diagram of reticle calibration method 600 according to an exemplary embodiment. FIG. 7 is a schematic diagram of k4 parameters 700 of reticle calibration method 600 shown in FIG. 6 according to an exemplary embodiment. FIG. 8 is a schematic diagram of k18 parameters 800 of reticle calibration method 600 shown in FIG. 6 according to an exemplary embodiment.

[0062]

[0083] FIG. 5 illustrates a reticle calibration method 500 according to an example embodiment. The reticle calibration method 500 can be configured to reduce the effects of heating and / or cooling the reticle 300 in a lithography process. The reticle calibration method 500 can further be configured to increase the accuracy and speed of calibration of the reticle heating model, thereby increasing the manufacturing throughput and yield of the lithography process. Although the reticle calibration method 500 is illustrated in FIG. 5 as a standalone method and / or system, aspects of the disclosure may be used in conjunction with other apparatus, systems, and / or methods, such as, but not limited to, the lithographic apparatus LA, the lithographic cell LC, the computer system CL, the metrology tool MT, the support structure MT, the patterning device MA, the reticle exchange apparatus 100, the reticle stage 200, the reticle 300, the IVR 400, and / or the reticle calibration method 600.

[0063]

[0084] 5, reticle calibration method 500 may include reticle temperature 502, process flow 504, conditioning stage 510, calibration stage 520, and / or processing stage 530. Conditioning stage 510 may be configured to adjust the initial temperature of reticle 300 to a predetermined temperature. In one embodiment, the initial temperature of reticle 300 may be in a range of about 20° C. to about 24° C., depending on where reticle 300 comes from in the lithography system (e.g., IRL, external metrology tool MT, reticle stage 200, integrated reticle inspection system (IRIS), etc.). For example, reticle 300 may initially be in a “hot” state (e.g., a reticle temperature greater than 22° C.±0.2° C.), a “cold” state (e.g., a reticle temperature less than 22° C.±0.2° C.), and a “fully conditioned” state (e.g., a reticle temperature of 22° C.±0.2° C.). In one embodiment, conditioning step 510 cools and / or heats reticle 300 to a predetermined temperature (eg, 22° C.±0.2° C.), as indicated by adjusted reticle temperature 512 .

[0064]

[0085] In some embodiments, reticle 300 can be conditioned (e.g., heated and / or cooled) by the IRL. For example, reticle 300 can be placed in the IRL for approximately 40 minutes to reach a predetermined temperature (e.g., 22°C ± 0.2°C). In some embodiments, reticle 300 can be conditioned (e.g., heated and / or cooled) by a conditioning slot that rapidly heats and / or cools reticle 300 to a predetermined temperature (e.g., 22°C ± 0.2°C). For example, the conditioning slot can include a resistive heater and / or a nozzle that flows a gas (e.g., air, nitrogen, argon, helium, etc.) over reticle 300 to rapidly heat and / or cool reticle 300 to a predetermined temperature (e.g., 22°C ± 0.2°C) in approximately 5 minutes, for example, for an initial temperature of approximately 22°C ± 2°C.

[0065]

[0086] In some embodiments, the adjusting step 510 may include RA and / or RSD measurements to determine the time at which the reticle 300 reaches a predetermined temperature (e.g., 22°C ± 0.2°C). For example, one or more alignment marks 310 and / or one or more edge alignment marks 320 on the reticle 300 may be measured to determine the adjusted reticle temperature 512. In some embodiments, the RSD measurements may be converted to the adjusted reticle temperature 512 through FEM. In some embodiments, the adjusting step 510 may include RA measurements between the reticle 300 and a non-production substrate. For example, the non-production substrate may include one or more CTC wafers for alignment and / or reticle temperature calibration.

[0066]

[0087] In some embodiments, conditioning step 510 may include conditioning reticle 300 on reticle stage 200 by determining the time at which reticle 300 reaches a predetermined temperature (e.g., 22°C ± 0.2°C) using a certain number of product substrates. For example, when reticle 300 is in a "hot" state (e.g., a reticle temperature greater than 22°C ± 0.2°C), a maximum of about 40 or fewer product substrates (e.g., about 22 to about 26 wafers) may be required to condition the production lot, while when reticle 300 is near a "fully conditioned" state (e.g., 22°C ± 0.2°C), a minimum of about 2 or more product substrates (e.g., about 2 to about 6 wafers) may be required to condition the production lot.

[0067]

[0088] In some embodiments, adjusting step 510 can include adjusting reticle 300 in reticle stage 200 by using decision-based learning and / or machine learning to determine when reticle 300 reaches a predetermined temperature (e.g., 22°C ± 0.2°C). For example, decision-based learning and / or machine learning can include using regression, local regression, nonparametric local regression, kernel regression, multivariate adaptive regression, regression trees, Gaussian process regression, support vector regression, splines, smoothing splines, nearest neighbors, neural networks, adaptive windows, Kalman filtering, linear-quadratic estimation, or combinations thereof.

[0068]

[0089] In some embodiments, the adjusting step 510 may include adjusting the reticle 300 in the reticle stage 200 by determining the time at which the reticle 300 reaches a predetermined temperature (e.g., 22°C ± 0.2°C) using KPIs based on the RA and / or RSD measurements. For example, as shown in Figures 7 and 8, the k4 parameters 700 and / or k18 parameters 800 may be measured, and convergence (e.g., convergence > 90%) of the average k4 parameters 710 and / or average k18 parameters 810 may be used to determine the temperature of the reticle 300 and / or the calibration of the reticle heating model.

[0069]

[0090] Calibration stage 520 can be configured to calibrate the reticle heating model by exposing reticle 300 and a non-production substrate to a radiation dose. In one aspect, the initial temperature of reticle 300 at the start of calibration stage 520 is a predetermined temperature (e.g., 22°C ± 0.2°C) in a “fully conditioned” state. In one aspect, calibration stage 520 further heats reticle 300 to a dose product temperature (e.g., greater than 22°C ± 0.2°C) in a “hot” state, as indicated by calibration reticle temperature 522. In one aspect, during calibration stage 520, a non-production substrate is exposed to a radiation dose to enable in-line calibration of the reticle heating model in the product environment itself. In one aspect, an initial estimate of the parameters (e.g., x) that need to be calibrated is made based on the reticle heating model (e.g., FEM) and the reticle temperature (e.g., calibration reticle temperature 522).

[0070]

[0091] In some embodiments, an initial estimate of the parameters of the reticle heating model may be based on calibration (e.g., RA measurements) of one or more non-production substrates (e.g., CTC wafers). For example, the reticle heating model may be evaluated for one or more non-production substrates, e.g., until convergence (e.g., convergence ≧90%) of the parameters in the reticle heating model is reached. In some embodiments, once calibration of the reticle heating model is completed with one or more non-production substrates, product substrates of a production lot are initiated, and calibration based on RA measurements continues throughout processing stage 530.

[0071]

[0092] In some embodiments, calibration step 520 may include RA and / or RSD measurements to determine the temperature of reticle 300. In some embodiments, calibration step 520 may include in-line real-time calibration of the reticle heating model based on one or more non-production substrates and / or one or more non-production lots. For example, in a particular step (e.g., adjustment step 510), reticle temperatures may be compared between two different non-production substrates and / or non-production lots, and the difference (e.g., differential reticle temperature ΔT) or trend (e.g., ΔT=0.5° C.) may be adjusted in the reticle heating model.

[0072]

[0093] In some embodiments, the calibration step 520 may include evaluating a reticle heating model for each RA measurement between the reticle and a plurality of non-production substrates of a non-production lot. For example, the evaluation may be performed using the following equation: x 新 =x 旧 +γ (x 旧 -RA 結果 ) where γ is a gain value configured to remove noise. For example, γ may be equal to any number in the interval [−1, 1] (e.g., −1, −0.5, −0.1, 0.1, 0.5, 1). For example, evaluating may include measuring RA for each of a plurality of non-production substrates until convergence (e.g., ≧90%) is reached.

[0073]

[0094] In some embodiments, calibration stage 520 can be further configured to adapt (e.g., heat) reticle 300 to a dose temperature by exposing reticle 300 and a non-production substrate to a radiation dose. In one embodiment, the initial temperature of reticle 300 at the start of calibration stage 520 is a predetermined temperature (e.g., 22°C ± 0.2°C) in a "fully conditioned" state. In one embodiment, calibration stage 520 heats reticle 300 to a dose temperature (e.g., about 24°C), as indicated by calibration reticle temperature 522. In some embodiments, calibration stage 520 can include RA and / or RSD measurements to determine the temperature of reticle 300. In some embodiments, the non-production substrate can include one or more CTC wafers for dose calibration.

[0074]

[0095] Processing stage 530 can be configured to process (e.g., fabricate) a product substrate by exposing reticle 300 and product substrate to a radiation dose based on a reticle heating model. In one embodiment, the initial temperature of reticle 300 at the start of processing stage 530 is the dose temperature (e.g., 24° C.). In one embodiment, processing stage 530 further heats reticle 300 to a dose product temperature (e.g., ≧24° C.) in a “hot” state, as shown by processing reticle temperature 532. In one embodiment, during processing stage 530, the product substrate is exposed to a radiation dose, allowing for in-line calibration of the reticle heating model in the product environment itself. In one embodiment, an initial estimate of a parameter (e.g., x) that needs to be calibrated is made based on the reticle heating model (e.g., FEM) and the reticle temperature (e.g., processing reticle temperature 532).

[0075]

[0096] In some embodiments, process stage 530 may be further configured to calibrate the reticle heating model by exposing reticle 300 and product substrates to a radiation dose. In some embodiments, once the calibration of the reticle heating model is completed with one or more non-production substrates (e.g., during calibration stage 520), product substrates of a production lot are initiated, and calibration based on RA measurements continues throughout process stage 530.

[0076]

[0097] In some embodiments, processing stage 530 can include RA and / or RSD measurements to determine the temperature of reticle 300. In some embodiments, processing stage 530 can include in-line real-time calibration of a reticle heating model based on one or more production substrates and / or one or more production lots. For example, at a particular stage (e.g., adjusting stage 510), reticle temperatures can be compared between two different production substrates and / or production lots, and the difference (e.g., differential reticle temperature ΔT) or trend (e.g., ΔT=0.5° C.) can be adjusted in the reticle heating model.

[0077]

[0098] In some embodiments, processing step 530 may include evaluating a reticle heating model for each RA measurement between the reticle and multiple product substrates in a production lot. For example, the evaluation may be performed using the following equation: x 新 =x 旧 +γ (x 旧 -RA 結果 ) where γ is a gain value configured to remove noise. For example, γ may be equal to any number in the interval [−1, 1] (e.g., −1, −0.5, −0.1, 0.1, 0.5, 1). For example, evaluating may include measuring RA for each of a plurality of product substrates until convergence (e.g., ≧90%) is reached.

[0078]

[0099] In some embodiments, reticle calibration method 500 may include performing separate RA and RSD measurements for each stage (e.g., conditioning stage 510, calibration stage 520, and processing stage 530). For example, an RA measurement may be performed at each stage, and an RSD measurement may be performed only once at each stage. In some embodiments, decision-based learning and / or machine learning used in conditioning stage 510 to determine the temperature of reticle 300 may also be used in calibration stage 520 and / or processing stage 530.

[0079]

[0100] In some aspects, reticle calibration method 500 can be implemented by a computer system CL, which can function as a controller and / or processor for controlling the various stages and measurements of reticle calibration method 500. In some aspects, reticle calibration method 500 can be implemented by a lithographic apparatus LA, which can include a controller and / or processor for controlling the various stages and measurements of reticle calibration method 500. In some aspects, reticle calibration method 500 can be implemented by a non-transitory computer readable medium program on a computer system CL, which can function as, for example, a controller and / or processor for controlling the various stages and measurements of reticle calibration method 500.

[0080]

[0101] For example, aspects of reticle calibration method 500 shown in Figure 5 and aspects of reticle calibration method 600 shown in Figure 6 may be similar. Like reference numbers are used to indicate features of the aspect of reticle calibration method 500 shown in Figure 5 and like features of the aspect of reticle calibration method 600 shown in Figure 6.

[0081]

[0102] FIG. 6 illustrates a reticle calibration method 600 according to an example embodiment. The reticle calibration method 600 can be configured to reduce the effects of heating and / or cooling the reticle 300 in a lithography process. The reticle calibration method 600 can further be configured to increase the accuracy and speed of calibration of the reticle heating model, thereby increasing the manufacturing throughput and yield of the lithography process. Although the reticle calibration method 600 is illustrated in FIG. 6 as a standalone method and / or system, aspects of the disclosure may be used in conjunction with other apparatus, systems, and / or methods, such as, but not limited to, the lithographic apparatus LA, the lithographic cell LC, the computer system CL, the metrology tool MT, the support structure MT, the patterning device MA, the reticle exchange apparatus 100, the reticle stage 200, the reticle 300, the IVR 400, and / or the reticle calibration method 500.

[0082]

[0103] 6, reticle calibration method 600 may include reticle temperature 602, process flow 604, conditioning stage 610, stress reduction stage 620, calibration stage 630, and / or processing stage 640. Conditioning stage 610 may be configured to adjust the initial temperature of reticle 300 to a predetermined temperature. In one embodiment, the initial temperature of reticle 300 may be in a range of about 20° C. to about 24° C., depending on where reticle 300 comes from in the lithography system (e.g., IRL, external metrology tool MT, reticle stage 200, IRIS, etc.). For example, reticle 300 may initially be in a “hot” state (e.g., a reticle temperature greater than 22° C.±0.2° C.), a “cold” state (e.g., a reticle temperature less than 22° C.±0.2° C.), and a “fully conditioned” state (e.g., a reticle temperature of 22° C.±0.2° C.). In one embodiment, the conditioning step 610 may include adjusting RA and RSD measurements 611 to determine an initial temperature of the reticle 300. In one embodiment, the conditioning step 610 cools and / or heats the reticle 300 to a predetermined temperature (e.g., 22° C.±0.2° C.), as indicated by adjusted reticle temperature 612 in FIG.

[0083]

[0104] In some embodiments, reticle 300 can be conditioned (e.g., heated and / or cooled) by the IRL. For example, reticle 300 can be placed in the IRL for approximately 40 minutes to reach a predetermined temperature (e.g., 22°C ± 0.2°C). In some embodiments, reticle 300 can be conditioned (e.g., heated and / or cooled) by a conditioning slot that rapidly heats and / or cools reticle 300 to a predetermined temperature (e.g., 22°C ± 0.2°C). For example, the conditioning slot can include a resistive heater and / or a nozzle that flows a gas (e.g., air, nitrogen, argon, helium, etc.) over reticle 300 to rapidly heat and / or cool reticle 300 to a predetermined temperature (e.g., 22°C ± 0.2°C) in approximately 5 minutes, for example, for an initial temperature of approximately 22°C ± 2°C.

[0084]

[0105] In some embodiments, the conditioning step 610 can include one or more RA and RSD measurements to determine the time at which the reticle 300 reaches a predetermined temperature (e.g., 22°C ± 0.2°C). For example, as shown in FIG. 6, an adjusted RA and RSD measurement 611 can be performed to determine the initial temperature of the reticle 300 in the conditioning step 610. For example, one or more alignment marks 310 (shown in FIGS. 3A and 3B) and one or more edge alignment marks 320 (shown in FIGS. 3A and 3B) on the reticle 300 can be measured to determine an adjusted reticle temperature 612. In some embodiments, the RSD measurement can be converted to an adjusted reticle temperature 612 through FEM. In some embodiments, the conditioning step 610 can include one or more RA measurements between the reticle 300 and a non-production substrate. 6, the conditioning stage 610 may include periodically measuring the reticle temperature 602 during the process flow 604 and making an adjusted RA and RSD measurement 611, a second adjusted RA measurement 614 (if needed), a third adjusted RA measurement 616 (if needed), and / or a fourth adjusted RA measurement 618 (if needed) to determine when the reticle 300 reaches a predetermined temperature (e.g., 22°C ± 0.2°C). For example, the non-production substrates may include one or more CTC wafers for alignment and / or reticle temperature calibration.

[0085]

[0106] In some embodiments, conditioning step 610 may include conditioning reticle 300 on reticle stage 200 by determining the time at which reticle 300 reaches a predetermined temperature (e.g., 22°C ± 0.2°C) using a certain number of product substrates. For example, when reticle 300 is in a "hot" state (e.g., a reticle temperature greater than 22°C ± 0.2°C), a maximum of about 40 or fewer product substrates (e.g., about 22 to about 26 wafers) may be required to condition the production lot, while when reticle 300 is near a "fully conditioned" state (e.g., 22°C ± 0.2°C), a minimum of about 2 or more product substrates (e.g., about 2 to about 6 wafers) may be required to condition the production lot.

[0086]

[0107] In some embodiments, the adjusting step 610 may include adjusting the reticle 300 in the reticle stage 200 by using decision-based learning and / or machine learning to determine when the reticle 300 reaches a predetermined temperature (e.g., 22°C ± 0.2°C). For example, the decision-based learning and / or machine learning may include using regression, local regression, nonparametric local regression, kernel regression, multivariate adaptive regression, regression trees, Gaussian process regression, support vector regression, splines, smoothing splines, nearest neighbors, neural networks, adaptive windows, Kalman filtering, linear-quadratic estimation, or combinations thereof. In some embodiments, the timing specifications (e.g., applied Kalman filtering) are aligned with the timing specifications (e.g., process window) of the lithography process with similar accuracy. In some embodiments, the adaptive window may be used to determine whether there is decay and / or drift in the KPIs (e.g., k4 parameters, k18 parameters). For example, four RA measurements (e.g., three previous measurements and the current measurement) may be taken, and a check may be performed to verify whether a change has occurred between the RA measurements. If a change is detected, the adjustment phase 610 continues, whereas if no change is detected, the adjustment phase 610 is completed (e.g., terminated). In some embodiments, the minimum time for the adjustment phase 610 is about 1 minute and the maximum time for the adjustment phase 610 is about 5 minutes.

[0087]

[0108] In some embodiments, the adjusting step 610 may include adjusting the reticle 300 in the reticle stage 200 by determining the time at which the reticle 300 reaches a predetermined temperature (e.g., 22°C ± 0.2°C) using KPIs based on the RA and / or RSD measurements. For example, as shown in Figures 7 and 8, the k4 parameters 700 and / or k18 parameters 800 may be measured, and convergence (e.g., convergence > 90%) of the average k4 parameters 710 and / or average k18 parameters 810 may be used to determine the temperature of the reticle 300 and / or calibration parameters for the reticle heating model. For example, as shown in FIG. 6 , the adjustment stage 610 may include an adjusted RA and RSD measurement 611, a second adjusted RA measurement 614, a third adjusted RA measurement 616, and / or a fourth adjusted RA measurement 618 to measure KPIs (e.g., k4 parameter 700, k18 parameter 800) to determine the time at which the reticle 300 reaches a predetermined temperature (e.g., 22°C ± 0.2°C).

[0088]

[0109] The stress reduction stage 620 can be configured to reduce parasitic thermal effects in the reticle 300. In one embodiment, as shown in FIG. 6, the stress reduction stage 620 can include a removal step 621 and a zero-dose step 622. The removal step 621 can be configured to release stress from the reticle 300 by transferring the reticle 300 from the reticle stage 200 to the IVR 400, thereby reducing parasitic thermal effects. The zero-dose step 622 can be configured to release stress from the reticle 300 by exposing the reticle 300 and the non-product substrate to a zero radiation dose, thereby reducing parasitic thermal effects. In one embodiment, the initial temperature of the reticle 300 at the start of the stress reduction stage 620 is a predetermined temperature (e.g., 22° C.±0.2° C.) in a “fully conditioned” state. In one aspect, stress reduction stage 620 reduces parasitic thermal effects in reticle 300 by releasing stress in reticle 300 in removal step 621, as indicated by stress reduced reticle temperature 624, and then exposing reticle 300 to light in zero dose step 622 to further reduce the parasitic thermal effects. In one aspect, stress reduction stage 620 maintains reticle 300 at a predetermined temperature (e.g., 22°C ± 0.2°C) in a "fully conditioned" state. In one aspect, zero dose step 622 can include zero dose RA and RSD measurements 623 to verify the temperature of reticle 300.

[0089]

[0110] In some embodiments, stress in reticle 300 can be reduced by removing reticle 300 from reticle stage 200 and quickly returning reticle 300 to reticle stage 200. For example, as shown in FIGS. 4A and 4B , reticle 300 can be unclamped from reticle cage 224 and clamps 250 on reticle stage 200, transferred to reticle base plate 406 of IVR 400, and then immediately transferred back to reticle stage 200 and clamped by reticle cage 224 and clamps 250. In some embodiments, stress in reticle 300 can be reduced by exposing reticle 300 and a non-product substrate (e.g., a CTC wafer) to a zero radiation dose. For example, as shown in FIG. 6 , after removal step 621, zero dose step 622 can be initiated and the reticle temperature can be verified again (e.g., via RA and / or RSD measurements). In some embodiments, the stress reduction step 620 can include RA and / or RSD measurements to determine the temperature of the reticle 300. For example, as shown in FIG. 6, zero-dose RA and RSD measurements 623 can be performed in the zero-dose step 622 to verify the initial temperature of the reticle 300. In some embodiments, the non-production substrates can include one or more CTC wafers for zero-dose calibration.

[0090]

[0111] Calibration stage 630 can be configured to calibrate the reticle heating model by exposing reticle 300 and a non-production substrate to a radiation dose. In one embodiment, the initial temperature of reticle 300 at the start of calibration stage 630 is a predetermined temperature (e.g., 22°C ± 0.2°C) in a "fully conditioned" state. In one embodiment, calibration stage 630 can include calibration RA and RSD measurements 631 to verify the temperature of reticle 300. In one embodiment, calibration stage 630 heats reticle 300 to a dose temperature (e.g., greater than 22°C ± 0.2°C), as indicated by calibration reticle temperature 632. In one embodiment, during calibration stage 630, a non-production substrate is exposed to a radiation dose to enable in-line calibration of the reticle heating model in the production environment itself. In one aspect, an initial guess of the parameters (eg, x) that need to be calibrated is made based on a reticle heating model (eg, FEM) and the reticle temperature (eg, calibration reticle temperature 632).

[0091]

[0112] In some embodiments, an initial estimate of the parameters of the reticle heating model may be based on calibration (e.g., RA measurements) of one or more non-production substrates (e.g., CTC wafers). For example, the reticle heating model may be evaluated for one or more non-production substrates, e.g., until convergence (e.g., convergence ≧90%) of the parameters in the reticle heating model is reached. In some embodiments, once calibration of the reticle heating model is completed with one or more non-production substrates, product substrates of a production lot are initiated, and calibration based on RA measurements continues throughout processing stage 640.

[0092]

[0113] In some embodiments, calibration stage 630 may include RA and / or RSD measurements to determine the temperature of reticle 300. For example, as shown in FIG. 6, calibration RA and RSD measurements 631 may be performed to verify the initial temperature of reticle 300 at the start of calibration stage 630. In some embodiments, calibration stage 630 may include in-line real-time calibration of a reticle heating model based on one or more non-production substrates and / or one or more non-production lots. For example, at a particular stage (e.g., adjustment stage 610), reticle temperatures may be compared between two different non-production substrates and / or non-production lots, and the difference (e.g., differential reticle temperature ΔT) or trend (e.g., ΔT=0.5° C.) may be adjusted in the reticle heating model.

[0093]

[0114] In some embodiments, the calibration stage 630 may include evaluating a reticle heating model for each RA measurement between the reticle 300 and a plurality of non-production substrates of a non-production lot. For example, the evaluation may be performed using the following equation: x 新 =x 旧 +γ (x 旧 -RA 結果 ) This may include updating a parameter x (eg, radiation dose, focus, alignment, etc.) of the lithography process by where γ is a gain value configured to remove noise. For example, γ may be equal to any number in the interval [−1, 1] (e.g., −1, −0.5, −0.1, 0.1, 0.5, 1). For example, evaluating may include measuring RA for each of multiple non-production substrates until convergence (e.g., ≧90%) is reached.

[0094]

[0115] In some embodiments, calibration stage 630 may further be configured to adapt (e.g., heat) reticle 300 to a dose temperature by exposing reticle 300 and a non-production substrate to a radiation dose. In one embodiment, the initial temperature of reticle 300 at the start of calibration stage 630 is a predetermined temperature (e.g., 22°C ± 0.2°C) in a “fully conditioned” state. In one embodiment, calibration stage 630 heats reticle 300 to a dose temperature (e.g., approximately 24°C), as indicated by calibration reticle temperature 632. In some embodiments, calibration stage 630 may include RA and / or RSD measurements to determine the temperature of reticle 300. For example, as shown in FIG. 6 , calibration RA and RSD measurements 631 may be performed to verify the initial temperature of reticle 300 during calibration stage 630. In some embodiments, the non-production substrate may include one or more CTC wafers for dose calibration.

[0095]

[0116] Processing stage 640 can be configured to process (e.g., fabricate) a product substrate by exposing reticle 300 and product substrate to a radiation dose based on a reticle heating model. In one embodiment, the initial temperature of reticle 300 at the start of processing stage 640 is the dose temperature (e.g., about 24°C). In one embodiment, processing stage 640 can include process RA and RSD measurements 641 to verify the temperature of reticle 300. In one embodiment, processing stage 640 further heats reticle 300 to a dose product temperature (e.g., ≧24°C) in a “hot” state, as indicated by processing reticle temperature 642. In one embodiment, during processing stage 640, the product substrate is exposed to a radiation dose, allowing for in-line calibration of the reticle heating model in the product environment itself. In one embodiment, an initial estimate of the parameters (e.g., x) that need to be calibrated is made based on the reticle heating model (e.g., FEM) and the reticle temperature (e.g., processing reticle temperature 642).

[0096]

[0117] In some embodiments, process stage 640 may be further configured to calibrate the reticle heating model by exposing reticle 300 and product substrates to a radiation dose. In some embodiments, once the calibration of the reticle heating model is completed with one or more non-production substrates (e.g., during calibration stage 630), product substrates of a production lot are initiated, and calibration based on RA measurements continues throughout process stage 640.

[0097]

[0118] In some embodiments, processing stage 640 can include RA and / or RSD measurements to determine the temperature of reticle 300. For example, as shown in FIG. 6, processing RA and RSD measurements 641 can be performed to verify the initial temperature of reticle 300 at the start of processing stage 640. In some embodiments, processing stage 640 can include in-line real-time calibration of a reticle heating model based on one or more production substrates and / or one or more production lots. For example, at a particular stage (e.g., adjusting stage 610), reticle temperatures can be compared between two different production substrates and / or production lots, and the difference (e.g., differential reticle temperature ΔT) or trend (e.g., ΔT=0.5° C.) can be adjusted in the reticle heating model.

[0098]

[0119] In some embodiments, processing step 640 may include evaluating a reticle heating model for each RA measurement between reticle 300 and multiple product substrates in a production lot. For example, the evaluation may involve evaluating a reticle heating model using the following equation: x 新 =x 旧 +γ (x 旧 -RA 結果 ) where γ is a gain value configured to remove noise. For example, γ may be equal to any number in the interval [−1, 1] (e.g., −1, −0.5, −0.1, 0.1, 0.5, 1). For example, evaluating may include measuring RA for each of a plurality of product substrates until convergence (e.g., ≧90%) is reached.

[0099]

[0120] In some embodiments, reticle calibration method 600 may include performing separate RA and RSD measurements for each stage (e.g., conditioning stage 610, stress reduction stage 620, calibration stage 630, and processing stage 640). For example, an RA measurement may be performed at each stage, and an RSD measurement may be performed only once at each stage. In some embodiments, the decision-based learning and / or machine learning used in conditioning stage 610 to determine the temperature of reticle 300 may also be used in stress reduction stage 620, calibration stage 630, and / or processing stage 640.

[0100]

[0121] In some embodiments, reticle calibration method 600 may utilize a comprehensive reticle heating model that covers all possible heating dynamics. For example, reticle calibration method 600 may avoid calibration stage 630 by using one or more predefined FEMs in the reticle heating model. In some embodiments, reticle calibration method 600 may utilize a central data pool to calibrate the reticle heating model. For example, the central data pool may include baseline and / or statistical values ​​(e.g., parameters of the reticle heating model) based on various internal (e.g., in-resist) data. In some embodiments, reticle calibration method 600 may include a sine sweep exposure for both reticle heating model calibration and lens calibration. For example, by using a sine sweep exposure (e.g., for a fixed period of time), various time constants may be extracted (e.g., using RA and / or RSD measurements) for the reticle heating model parameters and lens parameters for calibration.

[0101]

[0122] In some aspects, reticle calibration method 600 can be implemented by a computer system CL, which can function as a controller and / or processor for controlling the various stages and measurements of reticle calibration method 600. In some aspects, reticle calibration method 600 can be implemented by a lithographic apparatus LA, which can include a controller and / or processor for controlling the various stages and measurements of reticle calibration method 600. In some aspects, reticle calibration method 600 can be implemented by a non-transitory computer readable medium program on a computer system CL, which can function as, for example, a controller and / or processor for controlling the various stages and measurements of reticle calibration method 600.

[0102]

[0123] FIG. 7 illustrates k4 parameters 700 according to an example embodiment. The k4 parameters 700 can be configured to increase the accuracy and speed of calibration of a reticle heating model. The k4 parameters 700 can also be configured to determine the temperature of the reticle 300. The k4 parameters 700 represent Y-axis magnification distortion. Although the k4 parameters 700 are shown in FIG. 7 as a separate method and / or system, aspects of the disclosure may be used in conjunction with other apparatus, systems, and / or methods, such as, but not limited to, lithographic apparatus LA, lithographic cell LC, computer system CL, metrology tool MT, reticle calibration method 500, and / or reticle calibration method 600.

[0103]

[0124] 7, k4 parameters 700 can include intensity (arbitrary units) 702, wafer number 704, and average k4 parameters 710. In some embodiments, k4 parameters 700 can be measured based on distortion in RA and / or RSD measurements to determine the temperature of reticle 300. For example, as shown in FIG. 7, average k4 parameters 710 can be measured across several wafers, and convergence of average k4 parameters 710 (e.g., ≧90%) can be used to determine the temperature of reticle 300 and / or calibration parameters for the reticle heating model of reticle calibration method 500 and / or reticle calibration method 600. In some embodiments, k4 parameters 700 can be measured to determine the time at which reticle 300 reaches a predetermined temperature (e.g., 22° C.±0.2° C.).

[0104]

[0125] FIG. 8 illustrates k18 parameters 800 according to an example embodiment. The k18 parameters 800 can be configured to increase the accuracy and speed of calibration of a reticle heating model. The k18 parameters 800 represent Y-axis barrel shape distortion. Although the k18 parameters 800 are illustrated in FIG. 8 as a separate method and / or system, aspects of the disclosure may be used in conjunction with other apparatus, systems, and / or methods, such as, but not limited to, lithographic apparatus LA, lithographic cell LC, computer system CL, metrology tool MT, reticle calibration method 500, and / or reticle calibration method 600.

[0105]

[0126] 8, k18 parameters 800 can include intensity (arbitrary units) 802, wafer number 804, and average k18 parameters 810. In some embodiments, k18 parameters 800 can be measured based on distortion in RA and / or RSD measurements to determine the temperature of reticle 300. For example, as shown in FIG. 8, average k18 parameters 810 can be measured across several wafers, and convergence (e.g., ≧90%) of average k18 parameters 810 can be used to determine the temperature of reticle 300 and / or calibration parameters for the reticle heating model of reticle calibration method 500 and / or reticle calibration method 600. In some embodiments, k18 parameters 800 can be measured to determine the time at which reticle 300 reaches a predetermined temperature (e.g., 22° C.±0.2° C.).

[0106]

[0127] Exemplary Reticle Calibration Diagram

[0107]

[0128] 9 and 10 illustrate reticle calibration diagrams 900, 1000 for reducing the effects of heating and / or cooling a reticle 300 in a lithography process, according to example embodiments. FIG. 9 illustrates reticle calibration diagram 900 according to example embodiments. It should be understood that not all steps in FIG. 9 are required to practice the disclosure provided herein. Furthermore, some of the steps may be performed simultaneously, sequentially, and / or in a different order than shown in FIG. 9. Reticle calibration diagram 900 will be described with reference to FIGS. 3A, 3B, 4A, 4B, 5, and 6. However, reticle calibration diagram 900 is not limited to these example embodiments.

[0108]

[0129] In step 902, as shown in the examples of FIGS. 3A, 3B, 5, and 6, reticle 300 is conditioned (e.g., heated and / or cooled) to adjust the initial temperature of reticle 300 to a predetermined temperature (e.g., 22°C ± 0.2°C). In some embodiments, reticle 300 may be conditioned (e.g., heated and / or cooled) by an conditioned slot that rapidly heats and / or cools reticle 300 to the predetermined temperature (e.g., 22°C ± 0.2°C). In some embodiments, one or more RA and RSD measurements may be taken to determine the time at which reticle 300 reaches the predetermined temperature (e.g., 22°C ± 0.2°C). In some embodiments, decision-based learning and / or machine learning may be used to determine the time at which reticle 300 reaches the predetermined temperature (e.g., 22°C ± 0.2°C).

[0109]

[0130] In step 904, stress in reticle 300 is reduced (e.g., released) to reduce parasitic thermal effects in reticle 300, as shown in the examples of Figures 3A, 3B, 4A, 4B, and 6. In some embodiments, stress in reticle 300 can be released, thereby reducing parasitic thermal effects, by transferring reticle 300 from reticle stage 200 to IVR 400. In some embodiments, stress in reticle 300 can be released, thereby reducing parasitic thermal effects, by exposing reticle 300 and non-production substrates to a zero radiation dose.

[0110]

[0131] In step 906, the reticle heating model is calibrated by exposing reticle 300 and a non-production substrate to a radiation dose, as shown in the examples of FIGS. 3A, 3B, 5, and 6. In some embodiments, an initial estimate of the parameters of the reticle heating model may be based on calibration (e.g., RA measurements) of one or more non-production substrates (e.g., CTC wafers). In some embodiments, RA measurements and / or RSD measurements may be performed to determine the temperature of reticle 300. In some embodiments, in-line real-time calibration of the reticle heating model may be based on one or more non-production substrates and / or one or more non-production lots. In some embodiments, the reticle heating model may be evaluated for each RA measurement between reticle 300 and multiple non-production substrates in a non-production lot.

[0111]

[0132] In some embodiments, reticle 300 is adapted (e.g., heated) by exposing reticle 300 and a non-production substrate to a radiation dose during step 906. In some embodiments, RA and / or RSD measurements may be performed to determine the temperature of reticle 300. In some embodiments, the non-production substrate may include one or more CTC wafers for dose calibration.

[0112]

[0133] In step 908, product substrates are processed (e.g., manufactured) by exposing reticle 300 and product substrates to a radiation dose based on the reticle heating model, as shown in the examples of FIGS. 3A, 3B, 5, and 6. In some embodiments, RA measurements and / or RSD measurements may be performed to determine the temperature of reticle 300. In some embodiments, in-line real-time calibration of the reticle heating model may be based on one or more product substrates and / or one or more product lots. In some embodiments, the reticle heating model may be evaluated for each RA measurement between reticle 300 and multiple product substrates in a product lot.

[0113]

[0134] FIG. 10 illustrates a reticle calibration diagram 1000 according to an example embodiment. It should be understood that not all steps in FIG. 10 are required to practice the disclosure provided herein. Furthermore, some of the steps may be performed simultaneously, sequentially, and / or in a different order than that shown in FIG. 10. Reticle calibration diagram 1000 will be described with reference to FIGS. 3A, 3B, 4A, 4B, 5, and 6. However, reticle calibration diagram 1000 is not limited to these example embodiments.

[0114]

[0135] In step 1002, as shown in the examples of FIGS. 3A, 3B, 5, and 6, the reticle 300 is heated and / or cooled to a temperature (e.g., 22°C ± 0.2°C) based on the RSD measurement. In some embodiments, the RSD measurement can be converted to a reticle temperature through FEM. In some embodiments, the reticle 300 can be heated and / or cooled by an adjustment slot that rapidly heats and / or cools the reticle 300. In some embodiments, one or more RA and RSD measurements can be taken to determine when the reticle 300 reaches a predetermined temperature (e.g., 22°C ± 0.2°C). In some embodiments, decision-based learning and / or machine learning can be used to determine when the reticle 300 reaches a predetermined temperature (e.g., 22°C ± 0.2°C).

[0115]

[0136] In step 1004, reticle 300 is removed from reticle stage 200 and then returned to reticle stage 200 to release thermal stresses, as shown in the examples of Figures 3A, 3B, 4A, 4B, and 6. In some embodiments, transferring reticle 300 from reticle stage 200 to IVR 400 and quickly returning reticle 300 from IVR 400 to reticle stage 200 can release stresses (e.g., induced stresses, internal strains) in reticle 300, thereby reducing parasitic thermal effects.

[0116]

[0137] In step 1006, reticle 300 and the non-production substrate are exposed to a zero radiation dose to reduce parasitic thermal effects, as shown in the examples of Figures 3A, 3B, and 6. In some embodiments, exposing reticle 300 and the non-production substrate (e.g., a CTC wafer) to a zero radiation dose can release and / or relieve stress (e.g., residual stress) in reticle 300, thereby reducing parasitic thermal effects.

[0117]

[0138] In step 1008, the temperature of reticle 300 is measured based on RSD measurements, as shown in the examples of Figures 3A, 3B, 5, and 6. In some embodiments, RA measurements and / or RSD measurements can be performed to determine the temperature of reticle 300.

[0118]

[0139] In step 1010, reticle 300 and a non-production substrate are exposed to a radiation dose, as shown in the examples of Figures 3A, 3B, 5, and 6. In some embodiments, RA and / or RSD measurements may be performed to determine the temperature of reticle 300. In some embodiments, the non-production substrate may include one or more CTC wafers for dose calibration.

[0119]

[0140] In step 1012, as shown in the examples of FIGS. 3A, 3B, 5, and 6, the temperature of reticle 300 is measured based on RSD measurements, and the reticle heating model is calibrated based on the measured temperature of reticle 300. In some embodiments, RA measurements and / or RSD measurements may be performed to determine the temperature of reticle 300. In some embodiments, an initial estimate of the parameters of the reticle heating model may be based on calibration (e.g., RA measurements) of one or more non-production substrates (e.g., CTC wafers). In some embodiments, RA measurements and / or RSD measurements may be performed to determine the temperature of reticle 300. In some embodiments, in-line real-time calibration of the reticle heating model may be based on one or more non-production substrates and / or one or more non-production lots. In some embodiments, the reticle heating model may be evaluated for each RA measurement between reticle 300 and multiple non-production substrates of a non-production lot.

[0120]

[0141] In step 1014, the product substrate is processed (e.g., manufactured) by exposing the reticle 300 and the product substrate to a radiation dose based on the reticle heating model, as shown in the examples of FIGS. 3A, 3B, 5, and 6. In some embodiments, RA measurements and / or RSD measurements may be performed to determine the temperature of the reticle 300. In some embodiments, the in-line real-time calibration of the reticle heating model may be based on one or more product substrates and / or one or more product lots. In some embodiments, the reticle heating model may be evaluated for each RA measurement between the reticle 300 and multiple product substrates in a product lot.

[0121]

[0142] The above techniques allow for the determination of reticle heating calibration (RHC) data. RHC data provides information about how a reticle heats up from a cold state. RHC data may be used to improve the accuracy of reticle deformation estimates that rely on RA measurements.

[0122]

[0143] 5 and 6 illustrate the conditioning, calibration, and processing stages. During each of these stages, the temperature of the reticle is varied over a temperature range. RA measurements may be performed on the reticle at different temperatures within each temperature range. As described above, a model, such as an FEM model, may be used to determine the stresses and resulting deformations of the reticle. RHC data may be generated based on the RA measurements at different temperatures and the corresponding stresses and deformations at each temperature. The RHC data may then determine how the reticle heats up from a cold state and the resulting stresses and deformations. The deformation may be determined as a deformation mode, such as the k parameter described above.

[0123]

[0144] According to a first embodiment, RHC data is used to improve the accuracy of a reticle heating model. The reticle heating model may include the RHEA described above. The RHEA is a model in which the modeled deformation depends on the RA measurement. It is a deformation technique.

[0124]

[0145] 11 shows a deterministic reticle heating model, which includes an RHEA 1101, a reticle heating module 1102, and an uncertainty module 1103.

[0125]

[0146] Inputs to the RHEA may include a nominal reference state 1104 and RA feedback data 1105. The nominal reference state 1104 is data describing the initial state of the reticle. The nominal reference state 1104 may be retrieved from a library. The RA feedback data 1105 may include operational data such as the administered dose. The RHEA output 1106 may include heating dynamics determined by the RHEA 1101. The RHEA output 1106 may be provided to the reticle heating module 1102.

[0126]

[0147] The uncertainty module 1103 represents contributions to the actual deformation of the reticle that the deterministic reticle heating module cannot predict. Specifically, the uncertainty can include events such as changes in timing or changes that result in different boundary conditions.

[0127]

[0148] The reticle heating module 1102 may determine and output a mode shape that is a determination of the reticle deformation. Depending on the output of the reticle heating model, process modifications may be determined to alter the operation of the lithographic apparatus to at least partially address the reticle deformation.

[0128]

[0149] 11 is that the accuracy of the model is dependent on a reference state 1104 that describes the initial state of the reticle. The reference state 1104 assumes that the reticle is perfectly adjusted. Therefore, if the reticle is not perfectly adjusted, the accuracy of the reticle heating model can be significantly reduced.

[0129]

[0150] The actual arrival temperature of a reticle depends on the history of the reticle and can vary between approximately 20°C and 24°C. For example, if the reticle is transported from outside the lithography tool, the reticle temperature will depend on the temperature in the fab. If the reticle is delivered by a reticle stage, the reticle temperature will depend on the number of exposure processes performed using the reticle and the exposure process dose. If the reticle is delivered from a thermal conditioning slot, the reticle temperature will depend on the type of thermal conditioning slot and the length of time the reticle was in the conditioning slot.

[0130]

[0151] Thus, lithographic apparatus operators are faced with the choice of using improperly adjusted reticles and thus reducing overlay performance, or slowing down the operation of the lithographic apparatus to ensure that all reticles being used are properly adjusted.

[0131]

[0152] According to a first embodiment, the above problem is solved by providing a reticle heating model that can determine reticle deformation with improved accuracy when the reticle is not perfectly adjusted.

[0132]

[0153] Figure 12 illustrates a new deterministic reticle heating model according to the present embodiment. The model according to the present embodiment improves upon the model shown in Figure 11 by applying a calibration to a nominal reference state 1104. The applied calibration improves the accuracy of the model by at least partially reducing the effects of variable initial reticle temperatures.

[0133]

[0154] The model comprises an RHEA 1203, a reticle reference module (RRM) 1202, and a reference masker (RM) module 1201.

[0134]

[0155] The RRM input 1206 may include a nominal reference state. The input nominal reference state may be retrieved from a library and may be the same reference state 1104, which is the nominal data describing the initial state of the reticle, as described above.

[0135]

[0156] The RRM input 1206 may also include the RHC data mentioned above.

[0136]

[0157] The RRM input 1206 may also include reticle handling data, which may be received from the reticle handler 402. The reticle handling data may include data regarding how the reticle has been handled. The reticle handling data may include location data describing where the reticle has been. The reticle handling data may include time data describing how long the reticle has been at each location. The reticle handling data may include thermal data describing the temperature at each location the reticle has been at. The reticle handling data may include data regarding the thermal properties of the reticle at each location.

[0137]

[0158] The RRM input 1206 may also include current and / or previous outputs from the RHEA 1203 and other data.

[0138]

[0159] The RRM 1202 may receive updated input for each lot of substrates being processed and / or whenever there is an event on the reticle handler 402 .

[0139]

[0160] The RRM output 1210 may be data received by the RRM 1202 or data generated dependent on data received by the RRM 1202. The RRM output 1210 may be an input to the RM 1201. The RRM 1202 may provide the RRM output 1210 for each use of a reticle when the first RA measurement using the reticle is made.

[0140]

[0161] RM input 1204 may also include RA measurement data and exposure data. RM input 1204 may be provided to RM 1201 for each use of a reticle when the first RA measurement using the reticle is made.

[0141]

[0162] The RM 1201 may generate a calibrated reference state 1205 that is dependent on the data received by the RM 1201. The calibrated reference state is a determination of the shape and characteristics of the reticle when the reticle is in a cryogenic state. The RM output 1205 comprises the calibrated reference state. The RM 1201 may provide the RM output 1205 for each use of the reticle when the first RA measurement using the reticle is made.

[0142]

[0163] The RHEA 1203 may receive the RM output 1205 as an input.

[0143]

[0164] There may also be a communication path 1208 between the RHEA 1203 and the RRM 1202. The communication path may allow for communication of operational data, such as whether a failure or other processing delay has occurred.

[0144]

[0165] The RHEA input 1204 may also include RA measurement data and exposure data, which may be provided to the RHEA 1203 after each RA measurement and / or exposure process is performed.

[0145]

[0166] The RHEA may also receive RA feedback data 1209. The RA feedback data 1209 may be provided to the RHEA 1203 for each lot of substrates being processed and / or whenever there is an event in the reticle handler 402. The RA feedback data 1209 may be the same as the RA feedback data described above with reference to FIG.

[0146]

[0167] The RHEA 1203 may use the received input to determine heating dynamics. Specifically, the RHEA 1203 may determine the current shape of the reticle by relying on a determination of the shape of the reticle when it is in a cold state, the current temperature of the reticle (which may be inferred from RA measurements), and data regarding how the shape of the reticle changes as it heats from a cold state to the current temperature (provided by RHC data). This may allow the RHEA 1203 to perform more accurate determinations than techniques based solely on the nominal reference state 1104 without calibration that takes into account the current temperature of the reticle.

[0147]

[0168] RHEA output 1207 may include heating dynamics that may be input to reticle heating module 1102 for determining and outputting mode shapes that are determinations of deformation of the reticle, as described above with reference to Figure 11. Alternatively, there may be no reticle heating module 1102, and RHEA output 1207 may include determinations of mode shapes that are determinations of deformation of the reticle.

[0148]

[0169] RHEA output 1207 may be output from RHEA 1203 after each RA measurement and / or exposure process is performed.

[0149]

[0170] The operation of this embodiment is described in more detail below.

[0150]

[0171] At the start of processing a large number of substrates, the temperature of the reticle may be unknown and the reticle may be in a hot or cold state.

[0151]

[0172] RA measurements may be performed. RA measurement results may be input to RM 1201. RM 1201 may determine reference shape data for the reticle using data received by RRM 1202. RM 1201 may estimate reference reticle alignment data as follows:

[0152]

number

[0153]

[0173] In the above formula,

[0154]

number

[0155] is the estimated reference reticle alignment data based on the measured and stored reticle shape data. The measured and stored reticle shape data is filtered as denoted by F(...) to remove existing systematic effects on the reticle heating calibration KPIs (e.g., r4, rl8, rl0, etc.).

[0156]

[0174] The calibration process may separate stress effects from thermomechanical effects of reticle heating behavior. This may distinguish and reduce stress-induced effects. As previously described with reference to FIG. 6, the reticle may be cooled in a conditioning stage in which stress is present in the reticle. A stress reduction stage may then be performed to significantly reduce the stress. The substantially unstressed reticle may then be heated in the calibration and processing stages over a temperature range that substantially overlaps with the temperature range to which the reticle was cooled during the conditioning stage. Stress effects may be determined from a comparison of the stressed state of the reticle to a substantially stress-free state. Specifically, a filtering operation F(...) may be performed to eliminate systematic effects. Stage 1 represents the conditioning stage, and Stage 2,3 When represents the calibration and / or processing step, the comparison of the stressed state of the reticle to the substantially stress-free state is given by Δ 応力 may be determined as follows:

[0157]

number

[0158]

[0175] Δ 応力Using the calibrated reference Ref cal may be determined as follows:

[0159]

number

[0160]

[0176] The calibrated standard may be used to determine the cold state shape of the reticle, which may be used to adequately model the current state of the reticle despite incoming temperature fluctuations of the reticle.

[0161]

[0177] FIG. 13 shows the difference in the modeled ratio of overlay to reticle temperature when multiple substrates W are processed for both the known model 1302 and the new model 1301 according to the present embodiment.

[0162]

[0178] In FIG. 13, the y-axis represents the modeled ratio of overlay to reticle temperature. The x-axis represents the processing time of the substrate lot. The known model 1302 does not use a calibrated reference state of the reticle and incorrectly assumes that the reticle is perfectly adjusted. The model 1301 according to this embodiment improves on the known model by using a calibrated standard to determine a calibrated reference state 1205. The calibrated reference state 1205 may be used for all substrates within each lot. For each individual substrate lot, the reticle's cold state shape may be determined to appropriately determine the reticle's current shape.

[0163]

[0179] This embodiment improves the accuracy of the modeled state of the reticle, which allows for more appropriate process corrections to be applied in response to the modeled reticle deformations, improving overlay performance without reducing the productivity of the system. The performance of the model may be less sensitive to temperature changes of the reticle, thus improving the accuracy of the model when a reticle that is not in a perfectly adjusted state is used. The overlay impact caused by using a hot reticle may be reduced by approximately half, reducing the sensitivity of the system to variations in the applied process corrections. This embodiment does not require a temperature sensor to measure the temperature of the reticle.

[0164]

[0180] According to a second embodiment, a technique is provided to improve the accuracy of the reticle heating model when fast lot transitions occur.

[0165]

[0181] A lithography process performed on a substrate may involve using a first reticle for a lot of substrates, using a second reticle for a lot of substrates, and then reusing the first reticle for a lot of substrates. This may occur, for example, when a first pattern is required for a first layer of substrates, a second pattern is required for a second layer of substrates, and the same first pattern is required again for a third layer of substrates.

[0166]

[0182] Before its first use, the first reticle may initially be in a cold state and conditioned to a condition suitable for use in the IRL. The first reticle may then be heated when used in a first lithography process performed on a lot of substrates. The first reticle then cools down during this period because it is not in use when a lithography process using a second reticle is performed. The first reticle is then reused. The period between the end of the first use of the first reticle and its reuse may not be sufficient for the first reticle to cool down to a cold state.

[0167]

[0183] FIG. 14 shows a schematic diagram of the overlay error that can be caused by reticle temperature if no process is performed that corrects the cause of the overlay error. During period A1, the reticle is in use and heated. During period B, the reticle is not in use and cools down. During period A2, the reticle is reused. FIG. 14 illustrates that if period B is short, the reticle may not be able to cool down to the same low temperature state as at the beginning of period A1. If the reticle heating model assumes that the reticle is in a low temperature state at the beginning of period A2, the modeled reticle deformation will be inaccurate. Therefore, any process corrections determined to address the reticle heating will also be inaccurate. This is sometimes referred to as the ABA lot sequencing problem or the fast lost transition problem.

[0168]

[0184] The present embodiments provide a technique for determining when a fast lot transition occurs, which may be used to improve the accuracy of reticle heating models.

[0169]

[0185] According to this embodiment, the handling of the reticle is tracked and used to generate reticle handling data. The reticle handling data includes data regarding each location the reticle has been at and the amount of time the reticle was at each location. A determination of whether a fast lot transition has occurred is made depending on the reticle handling data and the known thermal properties of the reticle. A decision may then be made as to how to configure the reticle heating model depending on whether a fast lot transition has occurred.

[0170]

[0186] When the reticle is first loaded onto the reticle stage, the reticle heating model is initialized based on the assumption that the reticle is in a cold state. The cold state is the state of the reticle that has been properly adjusted by the IRL. Initializing the reticle heating model may include setting reference data based on the first reticle alignment measurement of a substrate in a lot. The reference data may include, for example, the nominal reference state 1104 described in the first embodiment. All states of the model may be initialized to zero or other default values ​​when the reticle is in a cold state.

[0171]

[0187] Once the first lot of substrates is processed, the state of the reticle heating model is updated to model the heating and resulting reticle deformation that occurs.

[0172]

[0188] After a first lot of substrates has been processed, a lot transition process may occur. All states of the reticle heating model at the end of processing the first lot of substrates are saved. Thereafter, a lithography process may be performed using a different reticle, or no lithography process may be performed.

[0173]

[0189] Reticle handling data may be generated for each reticle that may be used in a lithography process being performed. The reticle handling data may include data regarding how the reticle has been handled. The reticle handling data may include location data that describes locations where the reticle has been. The reticle handling data may include time data that describes how long the reticle has been at each location. The time data may also include data regarding when each lithography process performed using the reticle starts and ends, as well as when other related processes start and end. The reticle handling data may include thermal data that describes the temperature at each location where the reticle has been. The reticle handling data may include data regarding the thermal properties of the reticle at each location. The reticle handling data in this embodiment may be the same as the reticle handling data generated and used in the first embodiment.

[0174]

[0190] According to this embodiment, at the beginning of each reticle reuse process, a determination of the reticle's state is made dependent on the reticle handling data. Specifically, an estimate of the reticle's temperature may be made dependent on the reticle handling data. If the estimated temperature is equal to or greater than a threshold, a determination that the reticle is in a hot state may be made. A determination that the reticle is in a hot state may be equivalent to a determination that a fast lot transition has occurred. If the estimated temperature is less than the threshold, a determination that the reticle is in a cold state may be made. A determination that the reticle is in a cold state may be equivalent to a determination that a fast lot transition has not occurred.

[0175]

[0191] If the reticle is determined to be in a cold state, the reticle heating model for the process of reusing the reticle is reinitialized similarly to the process performed using the reticle in a cold state. Reinitializing the reticle heating model may include setting reference data based on the first reticle alignment measurement of the substrate in the lot. The reference data may include, for example, the nominal reference state 1104 described in the first embodiment. All states of the model may be initialized to zero or other default values ​​when the reticle is in a cold state.

[0176]

[0192] Alternatively, if the reticle is determined to be in a high temperature state, the reticle heating model for the process that reuses the reticle is initialized using a previously saved state of the reticle heating model at the end of processing a previous lot of substrates that used the reticle, thereby better initializing the model taking into account the state of the reticle.

[0177]

[0193] Advantageously, the reticle handling data allows for the detection of fast lot transitions, such as ABA scenarios, and provides for better initialization of the reticle heating model when the reticle loaded at the start of the process is in a hot state rather than a cold state. The techniques of the present embodiments may significantly reduce errors caused by the sensitivity of the reticle heating model to fast lot transitions. The techniques of the present embodiments may be applied computationally and do not reduce the throughput of the lithography apparatus.

[0178]

[0194] This embodiment may be used with any reticle heating model. This embodiment may be used in combination with the first embodiment. Specifically, determining the state of the reticle may be performed by the RRM 1202, which receives reticle handling data. Thus, the RRM 1202 may be a decision-making module.

[0179]

[0195] According to a third embodiment, a technique is provided for improving the accuracy of the reticle heating model when track disturbances occur.

[0180]

[0196] A track disturbance may be generally defined as any timing anomaly that may occur when a lithography process is performed. Examples of track disturbances include any event that causes an unintended delay in substrate load time, a computer malfunction that delays a commanded operation, or any of the many other unplanned events that may occur.

[0181]

[0197] The same reticle is used during lithography processes on multiple substrates within a lot. Track disturbances can occur during the processing of a lot. Known reticle heating models do not account for track disturbances. Therefore, the occurrence of track disturbances can cause inaccuracies in the reticle heating model to the extent that the effect of the disturbances on the actual thermal state of the reticle is not modeled.

[0182]

[0198] The present embodiment provides a technique for detecting the occurrence of a track disturbance and determining whether it is appropriate to reinitialize a reticle heating model in response to the occurrence of a track disturbance, which may be used to improve the accuracy of the reticle heating model.

[0183]

[0199] According to this embodiment, while the reticle remains loaded and clamped on the reticle stage, processes using the reticle are tracked and used to generate reticle process data. The reticle process data includes timing data for exposure processes performed using the reticle and other processes using the reticle while the reticle is clamped to the stage. A reticle heating model may be established depending on the reticle process data. Specifically, the occurrence and effects of track disturbances may be determined according to the reticle process data and known thermal properties of the reticle. The reticle heating model may then be established depending on whether the track disturbance has substantially affected the thermal properties of the reticle.

[0184]

[0200] This embodiment is described in more detail below.

[0185]

[0201] When a reticle is initially loaded onto the reticle stage, the reticle heating model may be initialized based on the assumption that the reticle is in a cold state. The cold state is the state of the reticle that has been properly adjusted by the IRL. Initializing the reticle heating model may include setting reference data based on a first reticle alignment measurement performed on the first substrate in the lot. The reference data may include, for example, the nominal reference state 1104 described for the first embodiment. All states of the reticle heating model may be initialized to zero or other default values ​​when the reticle is in a cold state.

[0186]

[0202] Once the first lot of substrates is processed, the state of the reticle heating model is updated to model the heating and resulting reticle deformation that occurs.

[0187]

[0203] Reticle process data is generated that includes timing data for exposure processes performed using the reticle, data for the dose of each exposure process, and data for other processes that affect the properties of the reticle while the reticle remains clamped on the reticle stage. The reticle process data may be monitored and used to determine when a track failure has occurred. For example, a track failure may be determined to have occurred if an exposure process has not been performed within an expected time window for the exposure process. The determination that a track failure has occurred may also depend on other parts of the overall lithography system. For example, a determination that a track failure has occurred may depend on the operation of a substrate handler.

[0188]

[0204] If a determination is made that a track failure has occurred, the effect of the track failure on the reticle is determined. The duration of the track failure may be known from reticle process data. The thermal characteristics of the reticle may also be known. The reticle process data and the known thermal characteristics of the reticle may be used to determine whether the duration of the track failure was long enough to significantly change the temperature of the reticle. Specifically, the temperature change of the reticle may be estimated. If the temperature change is equal to or greater than a threshold, it may be determined that a long track failure has occurred. If the temperature change is less than the threshold, it may be determined that a short track failure has occurred.

[0189]

[0205] Use of the reticle, which remains clamped to the stage, is resumed as soon as the track disturbance ends, and a reticle heating model for the reticle is set depending on whether the track disturbance was determined to be a short track disturbance or a long track disturbance.

[0190]

[0206] If the track disturbance is determined to be a short track disturbance, the reticle heating model is configured based on the state of the heating model before the track disturbance occurred, i.e., the reticle heating model may not be effectively reset and may operate as if the track disturbance had not occurred.

[0191]

[0207] If the track fault is determined to be a long track fault, the reticle heating model may be reset as if the reticle were in a cold state. That is, the reticle heating model may be reset to the same states used to initialize the reticle heating model when the reticle was first loaded onto the reticle stage. All states of the reticle heating model may be initialized to zero or other default values ​​when the reticle is in a cold state.

[0192]

[0208] Advantageously, the present embodiment provides a more appropriate setting of the reticle heating model when track disturbances occur. The technique of the present embodiment may significantly reduce errors caused by the sensitivity of the reticle heating model to temperature changes of the reticle due to track disturbances. The technique of the present embodiment may be applied computationally and does not reduce the throughput of the lithographic apparatus.

[0193]

[0209] This embodiment may be used with any reticle heating model. This embodiment may be used in combination with all other embodiments described throughout this document. Specifically, the determination of whether a long track failure or a short track failure has occurred may be performed by RRM 1202. Thus, RRM 1202 may be a decision-making module. RRM 1202 may generate reticle processing data or receive reticle processing data from another source. Known thermal characteristics of the reticle may be stored in RRM 1202 or provided to RRM 1202 from an external database.

[0194]

[0210] According to the fourth embodiment, a new technique for determining and accounting for the effects of clamping force is provided, which may be used in combination with the reticle heating model of the first embodiment and / or any of the techniques of the other embodiments described throughout this document.

[0195]

[0211] As previously explained, the reticle is clamped to the reticle stage 200. A potential problem is that the clamping force holding the reticle can change over time. This can be caused, for example, by frictional stresses locking in between the reticle and the reticle stage 200. Substantial changes in clamping force can occur over a period of approximately 4-8 hours and, if not addressed, can increase overlay error by approximately 2 nm.

[0196]

[0212] It is known to correct for distortion caused by variations in clamping force by using edge mark RA measurements and incorporating the measurement data into a reticle heating model. However, this reduces substrate productivity by approximately 7 substrates per hour. Inaccuracies in each edge mark measurement also reduce the accuracy of the reticle heating model. Edge mark measurements also reduce the resist coating performance of substrates W.

[0197]

[0213] 15 shows a reticle 1501. Reticle 1501 is surrounded by horizontally aligned and vertically aligned edge markers 1502, 1503, 1504, 1505, 1506, and 1507. Horizontally aligned edge markers 1502 and 1503 include upper horizontal edge marker 1502 and lower horizontal edge marker 1503. Vertically aligned edge markers 1504, 1505, 1506, and 1507 include central vertical edge marker 1505, upper vertical edge marker 1504, lower vertical edge marker 1507, and non-central vertical edge marker 1506.

[0198]

[0214] 16 shows how RA measurements are obtained for a process performed on a lot of substrates according to known techniques. For the first substrate in the lot, RA measurements are obtained from all of the horizontally and vertically aligned edge markers 1502, 1503, 1504, 1505, 1506, 1507, as indicated by RA 0. For each subsequent substrate in the lot, RA measurements are obtained from all of the horizontally aligned edge markers 1502, 1503, and at least the central vertical edge marker 1505, as indicated by RA 1 through RA N.

[0199]

[0215] The RA measurements for each substrate may be fed into a reticle heating model and used to determine the overall deformed shape of the reticle. Specifically, measurements from the central vertical edge marker 1505 are used to determine the deformation caused by the clamping effect for each substrate.

[0200]

[0216] 17 illustrates an alternative technique for obtaining RA measurements for a process performed on a lot of substrates, according to an embodiment. For the first substrate in the lot, RA measurements may be obtained from some or all of the horizontally and vertically aligned edge markers 1502, 1503, 1504, 1505, 1506, 1507, as indicated by RA0. For each subsequent substrate in the lot, RA measurements are obtained only from some or all of the horizontally aligned edge markers 1502, 1503, as indicated by RA1 through RAN. Thus, the central vertical edge marker 1505 is measured only for the first substrate, but not for subsequent substrates.

[0201]

[0217] The RA measurements of the first substrate may be fed into a reticle heating model and used to determine the overall deformed shape of the reticle, including the shape of the reticle stage 200 and the effect of the clamps on the reticle stage 200. The same modeled deformation of the clamping effect is then used for the remaining substrates in the lot. Using the same model of clamping effect for each substrate in the lot is appropriate because it typically takes 5-6 minutes to process a lot of substrates, while the clamping effect typically varies over 4-8 hours. Thus, the clamping effect remains substantially unchanged as the lot of substrates is processed.

[0202]

[0218] RA measurements may also be used to separately measure deformations caused by clamping effects and reticle-induced deformations due to reticle heating, etc. System drift caused by clamping effects may then be measured and incorporated into calibrations to improve the accuracy of the modeled deformations.

[0203]

[0219] Advantageously, this embodiment increases substrate processing speed by requiring fewer RA measurements, and it avoids resist degradation that occurs when measuring the central vertical edge marker 1505 for every substrate in a lot.

[0204]

[0220] The RA measurements obtained in this embodiment may be used by a reticle deformation model to determine deformations caused by the clamping effect, and depending on the determined deformations, process modifications may be determined to at least partially address the deformations.

[0205]

[0221] The embodiment includes a reticle deformation model that includes a reticle heating model. Specifically, RA measurements obtained in the embodiment may be used by the aforementioned reticle heating model according to any of the other embodiments described herein. RA measurements of the first substrate in a lot may be used to initialize the reticle heating model.

[0206]

[0222] In a fifth embodiment, a novel technique is provided for determining deformation of a reticle shape caused by clamping of the reticle by a reticle clamp, and the determined deformation may be at least partially addressed.

[0207]

[0223] As previously mentioned, a reticle is fixed to reticle stage 200 by a reticle clamp. The clamping force applied to the reticle by the reticle clamp can deform the shape of the reticle. The distribution of the clamping force, and the resulting deformation of the reticle shape, can depend on the shape of the clamping surface.

[0208]

[0224] Reticle deformation caused by static clamping force can be determined and then addressed. However, a potential problem is that the clamping force holding the reticle is not static. That is, the clamping force can change over time, which can cause the resulting deformation of the reticle shape to change over time. Time-dependent changes in clamping force can be caused, for example, by frictional stresses between the reticle and the reticle stage 200. Substantial changes in clamping force can occur over a period of approximately 4-8 hours, which, if not addressed, can increase overlay error by approximately 2 nm.

[0209]

[0225] Due to the time-varying reticle deformation caused by clamping forces, known techniques often measure global reticle deformation so that the reticle deformation can be addressed. Specifically, known techniques obtain reticle RA and edge mark measurements for each substrate being processed using the reticle. The RA and edge mark measurements are then used to model the deformation of each substrate. Process corrections are then applied to address the determined deformation.

[0210]

[0226] A problem with known techniques is that the time required to obtain RA measurements and edge mark measurements reduces the overall productivity of the lithography system, and any inaccuracy in each edge mark measurement introduces errors, and obtaining edge mark measurements reduces the performance of resist coating on substrates W.

[0211]

[0227] In a fourth embodiment, clamp-induced deformations are determined and provided to a reticle heating model, which determines a total deformation of the reticle dependent on the determined clamp-induced deformations, and the modeled total deformation may then be provided to a deformation-based reticle heating controller.

[0212]

[0228] This embodiment provides a new technique for determining clamp-induced deformation. In contrast to the technique of the fourth embodiment, the determined clamp-induced deformation may be fed directly to a deformation-based reticle heating controller. The determined clamp-induced deformation may not be fed to a reticle heating model, or may be fed directly to both the deformation-based reticle heating controller and the reticle heating model.

[0213]

[0229] In this embodiment, the deformation of the reticle caused by the clamping force is determined in a manner that does not require edge mark measurements for each substrate. The overall deformation of the reticle may be modeled as a combination of contributions to the overall deformation from different deformation modes. This embodiment uses one or more previous measurements to determine the deformation mode caused by the clamping force. The determined deformation mode may be used to determine the reticle deformation caused by the clamping force and to determine appropriate process modifications to at least partially address the resulting reticle deformation. Advantageously, this embodiment increases throughput by requiring fewer edge measurements. Additionally, other problems associated with known techniques may be avoided or mitigated.

[0214]

[0230] When performing a lithography process to form features on a substrate, the shape of a reticle may be deformed by both heating effects and clamping forces applied by the reticle clamps. However, when a reticle is properly adjusted and initially loaded onto a reticle stage, substantially no reticle heating effects are experienced. That is, when a reticle is first used in a cold state, substantially no reticle heating effects are experienced. In the absence of substantial deformation due to reticle heating effects, the reticle clamping forces and the inherent deformation resulting from the cold state of the reticle may be a substantial contributor to overall reticle deformation.

[0215]

[0231] The effect of the resulting global reticle deformation may be measured from inspection of features formed on a substrate. In particular, it is known that features formed on a substrate may be inspected by a metrology apparatus, which may be used to determine one or more performance metrics of a lithography process performed on the substrate, such as overlay error, edge placement error, etc., for a product.

[0216]

[0232] According to this embodiment, a metrology tool is used to determine one or more performance metrics when using a reticle in a cold state. Therefore, the net contributions to the reticle deformation measured by the one or more performance metrics are the reticle deformation caused by clamping forces and the intrinsic deformation due to the cold state of the reticle. A deformation mode of the overall reticle deformation may be determined depending on the one or more performance metrics. The deformation mode may be determined by several known techniques, such as PCA analysis, singular value decomposition, and / or other techniques that may be implemented algorithmically.

[0217]

[0233] The clamping-induced deformation modes may be determined based on the deformation modes determined from one or more performance metrics and predetermined knowledge of the reticle's inherent deformation modes in a cold state. The reticle's inherent deformation modes in a cold state may be obtained from a library. The reticle's inherent deformation modes in a cold state may include data regarding the expected shape and / or deformation of the reticle when the reticle is unclamped and appropriately thermally conditioned to be in a cold state.

[0218]

[0234] Determining the clamp-induced deformation allows for prediction of the overall deformation resulting from using the reticle in a cold state before performing a lithography process using the reticle. The overall deformation may be predicted based on previously determined clamp-induced deformation and knowledge of the cold state of the reticle being used. Process modifications may then be made to at least partially address the predicted overall deformation. The determination and application of the process modifications may be performed inline.

[0219]

[0235] The clamp-induced deformation mode may be determined based on measurements of multiple reticles, each reticle in a cold state. Specifically, when processing multiple lots of substrates, the first use of a reticle in each lot may be the use of the reticle in a cold state. For each use of the reticle in a cold state, the clamp-induced deformation may be determined using the techniques described above. The clamp-induced deformation prediction used may be based on multiple previously determined clamp-induced deformations.

[0220]

[0236] The clamp-induced deformation modes, which may be determined as described above, may be used to calibrate a reticle deformation model to include the effects of reticle clamps. The reticle deformation model may also determine the overall deformation of the reticle depending on the expected deformation modes of the reticle in a cold state and / or reticle heating effects.

[0221]

[0237] According to this embodiment, when processing a lot of substrates, the determination of reticle deformation due to clamping effects is based on the clamp-induced deformation mode obtained as described above. Thus, the clamp-induced deformation is calculated based on one or more previously used reticles in a cold state. Because the processing time for a lot may be a few minutes, whereas a substantial change in clamping force may take 4-8 hours, it is appropriate to use the same recently determined clamp-induced deformation for the entire lot of substrates.

[0222]

[0238] The determined overall deformation of the reticle may include all of the determination of the heating-induced reticle deformation, the expected deformation of the reticle in a cold state, and the determination of the deformation caused by the clamping force, and may then be used to determine a process modification to at least partially address the overall deformation of the reticle.

[0223]

[0239] Advantageously, the present embodiments provide a model that determines the effects of clamping a reticle based on its modes. The techniques of the embodiments may be applied inline to predict changes in reticle deformation. The embodiments avoid the need for inline edge mark measurements of each substrate in a lot. Because the model is modal-based, the modal deformation shape may be adjusted based on the specific characteristics of the reticle and / or reticle clamp and / or how the reticle and / or reticle clamp are used. For example, the modal deformation model may be applied to various reticle layouts. The density of the deformation measurements may also be varied as appropriate to adjust the determination of parameters to correct for the deformation.

[0224]

[0240] This embodiment also allows for the measurement and monitoring of clamping force variations and drift, which provides useful performance information about the reticle clamp.

[0225]

[0241] The techniques of this embodiment may be used in combination with one or more of the techniques of the previous embodiments, particularly with the techniques of the fourth embodiment.

[0226]

[0242] FIG. 18 is a flowchart of the method according to the first embodiment.

[0227]

[0243] In step 1801, the method begins.

[0228]

[0244] In step 1803, initial reference shape data representing the shape of the reticle is obtained.

[0229]

[0245] In step 1805, reticle heating calibration (RHC) data, including reticle shape data and corresponding reticle alignment (RA) measurement data, is acquired at different reticle temperatures.

[0230]

[0246] In step 1807, calibrated reference shape data is generated depending on the initial reference shape data, the RHC data, and the RA measurement.

[0231]

[0247] In step 1809, the shape and / or deformation of the reticle is modeled based on the calibrated reference shape data.

[0232]

[0248] In step 1811, the operation of a lithography process using the reticle is controlled depending on the modeled shape and / or deformation.

[0233]

[0249] In step 1813, the method ends.

[0234]

[0250] FIG. 19 is a flowchart of a method according to the second embodiment.

[0235]

[0251] In step 1901, the method begins.

[0236]

[0252] In step 1903, a reticle heating model is initialized based on reference data of the reticle in a cold state and a first reticle alignment measurement of the reticle when it is used in a lithography process performed on a first lot of substrates.

[0237]

[0253] In step 1905, the state of the reticle heating model is updated as the lithography process is performed on the first lot of substrates.

[0238]

[0254] In step 1907, after the lithography process is performed on the first lot of substrates, the current state of the reticle heating model is stored.

[0239]

[0255] In step 1909, reticle handling data dependent on the handling of the reticle is generated.

[0240]

[0256] In step 1911, depending on the reticle handling data, a determination is made whether the reticle is in a hot or cold state prior to using the reticle in the lithography process performed on the second lot of substrates.

[0241]

[0257] In step 1913, the operation of a lithography process using the reticle is controlled depending on the modeled shape and / or deformation.

[0242]

[0258] In step 1915, the method ends.

[0243]

[0259] FIG. 20 is a flowchart of a method according to the third embodiment.

[0244]

[0260] In step 2001, the method begins.

[0245]

[0261] In step 2003, a reticle heating model is initialized depending on reference data for the reticle in a cold state and a first reticle alignment measurement of the reticle when it is used in a lithography process performed on a lot of substrates.

[0246]

[0262] In step 2005, the state of the reticle heating model is updated as the lithography process is performed on the lot of substrates.

[0247]

[0263] In step 2007, reticle process data is generated.

[0248]

[0264] In step 2009, a determination is made that a long track fault has occurred, dependent upon the reticle process data and known reticle thermal properties.

[0249]

[0265] In step 2011, in response to determining that a long track fault has occurred, the reticle heating model is reset to the same initialization state that was used at the beginning of the execution of the lithography process on the lot of substrates.

[0250]

[0266] In step 2013, the operation of a lithography process using the reticle is controlled depending on the modeled shape and / or deformation.

[0251]

[0267] In step 2015, the method ends.

[0252]

[0268] FIG. 21 is a flowchart of a method according to the fourth embodiment.

[0253]

[0269] In step 2101, the method begins.

[0254]

[0270] In step 2103, before performing a lithography process on a first substrate in the lot of substrates, reticle alignment (RA) measurements are performed using a first plurality of edge markers of the reticle positioned on a first pair of parallel edges of the reticle.

[0255]

[0271] In step 2105, before performing a lithography process on the first substrate, RA measurements are performed using a second plurality of edge markers of the reticle that are positioned on a second pair of parallel edges of the reticle that are perpendicular to the first pair of parallel edges.

[0256]

[0272] In step 2107, determining the shape and / or deformation of the reticle depending on the RA measurements of the first and second plurality of edge markers is performed using a reticle deformation model so that the lithography process performed on the first substrate is controlled depending on the determined shape and / or deformation.

[0257]

[0273] In step 2109, a further RA measurement is performed using only the first plurality of edge markers before performing a lithography process on a second substrate in the lot of substrates.

[0258]

[0274] In step 2111, a determination of the deformation of the reticle when performing the lithography process on the second substrate is made using a reticle deformation model, depending on both the further RA measurement and the RA measurement value obtained before performing the lithography process on the first substrate.

[0259]

[0275] In step 2113, the operation of a lithography process using the reticle is controlled depending on the modeled shape and / or deformation.

[0260]

[0276] In step 2115, the method ends.

[0261]

[0277] FIG. 22 is a flowchart of a method according to the fifth embodiment.

[0262]

[0278] In step 2201, the method begins.

[0263]

[0279] In step 2203, a lithography process is performed on the first substrate using the reticle in a cold state.

[0264]

[0280] In step 2205, one or more performance metrics of the lithography process are determined depending on the inspection of the first substrate.

[0265]

[0281] In step 2207, the clamp-induced deformation modes of the reticle are determined depending on one or more performance metrics.

[0266]

[0282] In step 2209, a process modification is determined and applied to the lithography process performed on the second substrate depending on the determined clamp-induced deformation mode.

[0267]

[0283] In step 2211, the method ends.

[0268]

[0284] The embodiments include several modifications and variations to the above techniques.

[0269]

[0285] In all of the above first to fifth embodiments, the reticle may be the reticle 300 described with reference to Figures 1 to 10. Embodiments also include where different types of reticles are used.

[0270]

[0286] In all of the above first through fifth embodiments, the reticle clamp may be clamp 250 described with reference to Figures 1 through 10. Embodiments also include where different types of reticle clamps are used.

[0271]

[0287] In all of the above first to fifth embodiments, the reticle stage may be reticle stage 200 described with reference to Figures 1 to 10. Embodiments also include where different types of reticle stages are used.

[0272]

[0288] In all of the above first to fifth embodiments, the reticle handler may be reticle handler 402 described with reference to Figures 1 to 10. Embodiments also include where different types of reticle handlers are used.

[0273]

[0289] In all of the above first to fifth embodiments, the substrate may be the substrate W described with reference to Figures 1 to 10. Embodiments also include where different types of substrates are used.

[0274]

[0290] In all of the above first to fifth embodiments, the lithography system may be the lithography system described with reference to Figures 1 to 10. Embodiments also include where different types of lithography systems are used.

[0275]

[0291] In a first embodiment, the RRM 1202 and the RM 1201 are separate modules. An embodiment also includes a single module that performs the tasks of both the RRM 1202 and the RM 1201.

[0276]

[0292] Embodiments may be used with any type of lithography system. For example, the lithography system may be an EUV system or a DUV system. The lithography system may be of any design and is not limited to the specific type of system shown in Figures 1-2B.

[0277]

[0293] In all embodiments, the above determinations may be performed by algorithms implemented in a computer system, which may also rely on the determinations to determine and apply process modifications to control the operation of the lithography system.

[0278]

[0294] Although specific reference may be made herein to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein have other applications, such as, for example, the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, LCDs, thin film magnetic heads, etc. In light of these alternative applications, those skilled in the art will recognize that when the terms "wafer" or "die" are used herein, they may be considered synonymous with the more general terms "substrate" or "target portion," respectively. Substrates referred to herein may be processed, before or after exposure, in, for example, a track unit (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology unit, and / or an inspection unit. Where appropriate, the disclosure herein may apply to these and other substrate processing tools. Furthermore, a substrate may be processed multiple times, for example to produce multi-layer ICs, and thus the term substrate, as used herein, may also refer to a substrate that already includes multiple processed layers.

[0279]

[0295] Although particular reference has been made above to the use of aspects in the field of optical lithography, it should be understood that aspects may also be used in other fields, for example imprint lithography, depending on the context, and are not limited to optical lithography. In imprint lithography, a topography in a patterning device defines the pattern created on a substrate. The topography of the patterning device may be imprinted into a layer of resist supplied to the substrate, and the resist is cured by applying electromagnetic radiation, heat, pressure, or a combination thereof. The patterning device is then removed from the resist, leaving a pattern in it once the resist has hardened.

[0280]

[0296] It is to be understood that the language or terminology herein is for purposes of description and not of limitation, and thus the language or terminology herein should be interpreted by one of ordinary skill in the art in light of the teachings herein.

[0281]

[0297] As used herein, the term "substrate" refers to a material onto which a layer of material is applied. In some aspects, the substrate itself may be patterned, and the material applied thereon may also be patterned or may remain unpatterned.

[0282]

[0298] The following examples are illustrative, but not limiting, of aspects of the present disclosure. Other suitable modifications and adaptations of the variety of conditions and parameters normally encountered in the art and obvious to those skilled in the art are within the spirit and scope of the present disclosure.

[0283]

[0299] Although specific reference may be made herein to the use of the apparatus and / or system in the manufacture of ICs, it should be expressly understood that such apparatus and / or system has many other possible applications. For example, they may be used in the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, LCD panels, thin film magnetic heads, etc. In light of these alternative applications, those skilled in the art will recognize that any use of the terms "reticle," "wafer," or "die" herein should be considered as being substituted for the more general terms "mask," "substrate," or "target portion," respectively.

[0284]

[0300] While specific embodiments have been described above, it will be understood that the embodiments may be practiced otherwise than as described, and such descriptions are not intended to limit the scope of the claims.

[0285]

[0301] It is understood that the "Description of the Invention" section, and not the "Summary" and "Abstract" sections, are intended to be used to interpret the claims. While the "Summary" and "Abstract" sections may describe one or more exemplary embodiments as envisioned by the inventors, they do not describe every exemplary embodiment and therefore are not intended to limit the scope of the embodiments and appended claims in any way.

[0286]

[0302] Aspects of the present invention have been described above using functional building blocks that illustrate implementations of specific functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of description. Alternative boundaries may be defined so long as the specific functions and relationships thereof are appropriately implemented.

[0287]

[0303] The above description of specific embodiments fully discloses the general nature of the embodiments, and thus, by applying knowledge within the skill of the art, such specific embodiments can be readily modified and / or adapted for various uses without undue experimentation and without departing from the general concept of the embodiments. Accordingly, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein.

[0288]

[0304] Embodiments include a first set of clauses numbered as follows: 1. Modeling the shape and / or deformation of the reticle; 1. A computer system configured to control operation of a lithography process using a reticle in dependence on the modeled shape and / or deformation, comprising: To model the shape and / or deformation of the reticle, a computer system Acquire initial reference shape data representing the shape of the reticle; acquiring reticle heating calibration (RHC) data including reticle shape data and corresponding reticle alignment (RA) measurement data at different reticle temperatures; generating calibrated reference shape data dependent on initial reference shape data, RHC data, and RA measurements; A computer system configured to model the shape and / or deformation of the reticle based on the calibrated reference shape data. 2. To generate the RHC data, a computer system: acquiring a first data set including reticle shape data and corresponding RA measurement data at different reticle temperatures as the temperature of the reticle decreases during a first period of time; acquiring a second data set including reticle shape data and corresponding RA measurement data at different reticle temperatures as the temperature of the reticle is increased during a second time period; configured to generate RHC data in dependence on the first data set and the second data set; The computer system of clause A1, wherein the second period of time is after the first period of time, and the process for reducing stress in the reticle is performed between the first period of time and the second period of time. 3. The computer system of clause A2, wherein the computer system is configured to determine the RHC data relying on a comparison of the first data set and the second data set. 4. The computer system of any one of clauses A1-A3, wherein the calibrated reference shape data is dependent on determining the shape of the reticle when the reticle is in a cryogenic state. 5. The computer system of any one of clauses A1-A4, wherein the calibrated reference shape data relies on determining the shape of the reticle when the reticle is heated from a cold state of the reticle to the current temperature. 6. The computer system of any one of clauses A1 to A5, wherein the calibrated reference shape data is relied upon to determine the stress-reduced state of the reticle. 7. Modeling the shape and / or deformation of the reticle; and 1. A method comprising: controlling operation of a lithography process using a reticle in dependence on modeled shapes and / or deformations, the method comprising: Modeling the shape and / or deformation of the reticle obtaining initial reference shape data representing the shape of a reticle; acquiring reticle heating calibration (RHC) data including reticle shape data and corresponding reticle alignment (RA) measurement data at different reticle temperatures; generating calibrated reference shape data dependent on initial reference shape data, RHC data, and RA measurements; and A method comprising modeling a shape and / or deformation of a reticle relying on calibrated reference shape data. 8. acquiring a first data set including reticle shape data and corresponding RA measurement data at different reticle temperatures as the temperature of the reticle decreases during a first period of time; acquiring a second data set including reticle shape data and corresponding RA measurement data at different reticle temperatures as the temperature of the reticle is increased during a second period of time; and generating the RHC data by generating the RHC data in dependence on the first data set and the second data set; The method of clause A7, wherein the second period of time is after the first period of time, and the process for reducing stress in the reticle is performed between the first period of time and the second period of time. 9. The method of clause A8, wherein the RHC data is determined dependent on a comparison of the first data set and the second data set. 10. The method of any one of clauses A7-A9, wherein the calibrated reference shape data relies on determining the shape of the reticle when the reticle is in a cold state. 11. The method of any one of clauses A7-A10, wherein the calibrated reference shape data relies on determining the shape of the reticle when the reticle is heated from a cold state of the reticle to the current temperature. 12. The method of any one of clauses A7 to A11, wherein the calibrated reference shape data is relied upon to determine a stress-reduced state of the reticle. 13. A computer system according to any one of clauses A1 to A6; a lithography apparatus, A system in which a computer system is configured to control the operation of a lithographic apparatus. 14. A device manufacturing method using a lithographic process, the device manufacturing method comprising a method according to any one of clauses A7 to A12. 15. A non-transitory computer readable medium program comprising computer readable instructions configured to cause a processor to control a lithographic apparatus according to the method of any one of clauses A7 to A12.

[0289]

[0305] An embodiment includes a second set of clauses numbered as follows: 1. Determining the shape and / or deformation of the reticle using a reticle heating model; 1. A computer system configured to control operation of a lithography process using a reticle in dependence on the modeled shape and / or deformation, comprising: The computer system initializing a reticle heating model dependent on reference data of the reticle in a cold state and a first reticle alignment measurement of the reticle when the reticle is used in a lithography process performed on a first lot of substrates; updating the state of the reticle heating model when the lithography process is performed on the first lot of substrates; storing a current state of the reticle heating model after the lithography process is performed on the first lot of substrates; generating reticle handling data dependent on the handling of the reticle; determining whether the reticle is in a hot state or a cold state prior to using the reticle in a lithography process performed on a second lot of substrates, dependent on the reticle handling data; if determining that the reticle is in a high temperature state, setting a starting state of the reticle heating model for the lithography process to be performed on the second lot of substrates depending on the state of the stored reticle heating model; and a computer system configured, when determining that the reticle is in a low temperature state, to reinitialize the reticle heating model based on reference data of the reticle in the low temperature state and a first reticle alignment measurement of the reticle when processing a second lot of substrates. 2. The computer system of clause B1, wherein the computer system is further configured to determine a reticle temperature dependent on the reticle handling data. 3. The computer system is configured to determine that the reticle is in a high temperature condition when the determined reticle temperature is above a threshold; The computer system of clause B2, wherein the computer system is configured to determine that the reticle is in a cold state if the determined reticle temperature is below a threshold value. 4. Reticle handling data is location data describing where the reticle is and has been; time data describing how long the reticle was at each location and / or when each of the lithography processes performed using the reticle began and ended; Thermal data describing the temperature at each location where the reticle was located; and Data on the thermal properties of the reticle at each location The computer system of any one of clauses B1 to B3, including one or more of: 5. The computer system of any one of clauses B1 to B4, wherein the first lot of substrates includes the same substrates as the second lot of substrates. 6. Determining the shape and / or deformation of the reticle using the reticle heating model; and 1. A method comprising: controlling operation of a lithography process using a reticle in dependence on modeled shapes and / or deformations, the method comprising: The method is initializing a reticle heating model dependent on reference data of the reticle in a cold state and a first reticle alignment measurement of the reticle when the reticle is used in a lithography process performed on a first lot of substrates; updating the state of the reticle heating model when the lithography process is performed on a first lot of substrates; storing a current state of the reticle heating model after a lithography process is performed on a first lot of substrates; generating reticle handling data dependent on handling of the reticle; determining whether the reticle is in a hot state or a cold state prior to using the reticle in a lithography process performed on a second lot of substrates, dependent on the reticle handling data; if determining that the reticle is in a high temperature state, setting a starting state of the reticle heating model for a lithography process performed on a second lot of substrates depending on the state of the stored reticle heating model; The method includes, when determining that the reticle is in a low temperature state, reinitializing a reticle heating model dependent on reference data of the reticle in the low temperature state and a first reticle alignment measurement of the reticle when processing a second lot of substrates. 7. The method of clause B6, further comprising determining the reticle temperature dependent on the reticle handling data. 8. If the determined reticle temperature is above a threshold, determining that the reticle is in a high temperature state; The method of clause B7, determining that the reticle is in a cold state if the determined reticle temperature is below a threshold. 9. Reticle handling data is location data describing where the reticle is and has been; time data describing how long the reticle was at each location and / or when each of the lithography processes performed using the reticle began and ended; Thermal data describing the temperature at each location where the reticle was located; and Data on the thermal properties of the reticle at each location A method according to any one of clauses B6 to B8, including one or more of: 10. The method of any one of clauses B6 to B9, wherein the first lot of substrates includes the same substrates as the second lot of substrates. 11. A computer system according to any one of clauses B1 to B5, a lithographic apparatus, wherein a computer system is configured to control operation of the lithographic apparatus. 12. A device manufacturing method using a lithography process, the device manufacturing method comprising a method according to any one of clauses B6 to B10. 13. A non-transitory computer readable medium program comprising computer readable instructions configured to cause a processor to control a lithographic apparatus according to the method of any one of clauses B6 to B10.

[0290]

[0306] An embodiment includes a third set of clauses numbered as follows: 1. Determining the shape and / or deformation of the reticle using a reticle heating model; 1. A computer system configured to control operation of a lithography process using a reticle in dependence on the modeled shape and / or deformation, comprising: The computer system initializing a reticle heating model dependent on reference data of the reticle in a cold state and a first reticle alignment measurement of the reticle when the reticle is used in a lithography process performed on a lot of substrates; updating the state of the reticle heating model as the lithography process is performed on the lot of substrates; Generate reticle process data; determining that a long track failure has occurred relying on reticle process data and known thermal characteristics of the reticle; A computer system configured, in response to determining that a long track fault has occurred, to reset the reticle heating model to the same initialization state used at the start of execution of the lithography process on the lot of substrates. 2. The computer system Relying on reticle process data to detect whether a track failure has occurred; determining that a short track failure has occurred relying on reticle process data and known thermal characteristics of the reticle; The computer system of clause C1, configured to, in response to determining that a short track failure has occurred, continue to use a reticle heating model based on the state of the reticle heating model when the track failure was detected. 3. The computer system A determination that the exposure process was not performed within the expected time window of the exposure process; and / or Determining that an unplanned change has occurred in the operation of a portion of a lithography system used to perform a lithography process using a reticle The computer system of clause C2, configured to detect that a track failure has occurred by relying on one or more of: 4. The computer system is configured to determine a temperature of the reticle dependent on the reticle process data and known thermal properties of the reticle; The computer system of any one of clauses C1-C3, wherein determining that a long track fault has occurred depends on a change in temperature of the reticle caused by the track fault being greater than a threshold. 5. The computer system of clause C4 when subordinate to clause C2, wherein determining that a short track fault has occurred is dependent on a change in reticle temperature caused by the track fault being less than a threshold. 6. Reticle process data timing data relating to an exposure process performed using the reticle; Data on the dose of each exposure process, and Data about any process that affects the reticle's properties while the reticle remains clamped on the reticle stage The computer system of any one of clauses C1 to C5, including one or more of: 7. The computer system of any one of clauses C1 to C6, wherein the reticle remains clamped to the reticle stage when a track disturbance occurs. 8. Determining the shape and / or deformation of the reticle using the reticle heating model; and 1. A method comprising: controlling operation of a lithography process using a reticle in dependence on modeled shapes and / or deformations, the method comprising: The method is initializing a reticle heating model dependent on reference data of the reticle in a cold state and a first reticle alignment measurement of the reticle when the reticle is used in a lithography process performed on a lot of substrates; updating the state of the reticle heating model as the lithography process is performed on the lot of substrates; generating reticle process data; determining that a long track failure has occurred relying on reticle process data and known thermal characteristics of the reticle; and The method includes, in response to determining that a long track fault has occurred, resetting the reticle heating model to the same initialization state used at the start of performing a lithography process on the lot of substrates. 9. Relying on reticle process data to detect whether a track failure has occurred; determining that a short track failure has occurred relying on reticle process data and known thermal characteristics of the reticle; and The method of clause C8, further comprising, in response to determining that a short track fault has occurred, continuing to use a reticle heating model based on the state of the reticle heating model when the track fault was detected. 10. Detecting that a track failure has occurred Determining that the exposure process was not performed within an expected time window for the exposure process; and / or Determining that an unplanned change has occurred in the operation of a portion of a lithography system used to perform a lithography process using a reticle. The method according to clause C9, comprising one or more of: 11. Further comprising determining a temperature of the reticle dependent on the reticle process data and known thermal properties of the reticle; The method of any one of clauses C8-C10, wherein determining that a long track fault has occurred depends on a change in temperature of the reticle caused by the track fault being greater than a threshold value. 12. The method of clause C11 when dependent on clause C9, wherein determining that a short track fault has occurred is dependent on the reticle temperature change caused by the track fault being less than a threshold value. 13. Reticle process data timing data relating to an exposure process performed using the reticle; Data on the dose of each exposure process, and Data about any process that affects the reticle's properties while the reticle remains clamped on the reticle stage The method of any one of clauses C8 to C12, including one or more of: 14. The method of any one of clauses C8 to C13, wherein the reticle remains clamped to the reticle stage when a track disturbance occurs. 15. A computer system according to any one of clauses C1 to C7; a lithography apparatus, A system in which a computer system is configured to control the operation of a lithographic apparatus. 16. A device manufacturing method using a lithographic process, the device manufacturing method comprising a method according to any one of clauses C8 to C13. 17. A non-transitory computer readable medium program comprising computer readable instructions configured to cause a processor to control a lithographic apparatus according to the method of any one of clauses C8 to C13.

[0291]

[0307] Embodiments include a fourth set of clauses numbered as follows: 1. Determining the shape and / or deformation of the reticle using a reticle deformation model; 1. A computer system configured to control operation of a lithography process using a reticle in dependence on the modeled shape and / or deformation, comprising: The computer system performing reticle alignment (RA) measurements using a first plurality of edge markers of the reticle positioned on a first pair of parallel edges of the reticle prior to performing a lithography process on a first substrate in the lot of substrates; performing RA measurements using a second plurality of edge markers of the reticle positioned on a second pair of parallel edges of the reticle that are mutually orthogonal to the first pair of parallel edges before performing a lithography process on the first substrate; determining a shape and / or deformation of the reticle in dependence on the RA measurements of the first and second plurality of edge markers using a reticle deformation model such that a lithography process performed on the first substrate is controlled in dependence on the determined shape and / or deformation; performing a further RA measurement using only the first plurality of edge markers before performing a lithography process on a second substrate in the lot of substrates; A computer system configured to determine, using a reticle deformation model, a deformation of the reticle when performing the lithography process on the second substrate, depending on both the further RA measurement and the RA measurement value obtained before performing the lithography process on the first substrate. 2. The lot of substrates includes three or more substrates, and the computer system: performing RA measurements using only the first plurality of edge markers between lithography processes performed on two successive substrates within the lot of substrates; The computer system described in clause D1, which is configured to determine the deformation of the reticle when performing a lithography process on each substrate using a reticle deformation model, depending on both the most recently performed RA measurement and an RA measurement value obtained before performing the lithography process on the first substrate. 3. The reticle deformation model is configured to determine clamp-induced reticle deformation before a lithography process is performed on the first substrate; The computer system of clause D1 or D2, wherein the same determined clamp-induced reticle deformation is used for all of the substrates in the lot. 4. The computer system of any one of clauses D1 to D3, wherein the computer system is configured to include clamp-induced reticle deformations in the initial state of the reticle heating model. 5. Determining the shape and / or deformation of the reticle using the reticle deformation model; and 1. A method comprising: controlling operation of a lithography process using a reticle in dependence on modeled shapes and / or deformations, the method comprising: The method is performing reticle alignment (RA) measurements using a first plurality of edge markers of the reticle positioned on a first pair of parallel edges of the reticle before performing a lithography process on a first substrate in the lot of substrates; performing RA measurements using a second plurality of edge markers of the reticle positioned on a second pair of parallel edges of the reticle, the second pair of parallel edges being mutually orthogonal to the first pair of parallel edges, before performing a lithography process on the first substrate; determining a shape and / or deformation of the reticle in dependence on the RA measurements of the first and second plurality of edge markers using a reticle deformation model such that a lithography process performed on the first substrate is controlled in dependence on the determined shape and / or deformation; performing a further RA measurement using only the first plurality of edge markers before performing a lithography process on a second substrate in the lot of substrates; and The method includes determining, using a reticle deformation model, the deformation of the reticle when performing the lithography process on the second substrate, depending on both the further RA measurement and the RA measurement value obtained before performing the lithography process on the first substrate. 6. The lot of substrates includes three or more substrates, and the method further comprises: performing RA measurements using only the first plurality of edge markers between lithography processes performed on two successive substrates within a lot of substrates; and The method described in clause D5 includes determining the deformation of the reticle when performing a lithography process on each substrate using a reticle deformation model, depending on both the most recently performed RA measurement and an RA measurement value obtained before performing the lithography process on the first substrate. 7. A reticle deformation model determines clamp-induced reticle deformation before a lithography process is performed on a first substrate; The method of clause D5 or D6, wherein the same determined clamp-induced reticle deformation is used for all of the substrates in the lot. 8. The method of any one of clauses D5 to D7, wherein the method includes including clamp-induced reticle deformation in the initial state of the reticle heating model. 9. A computer system according to any one of clauses D1 to D4; a lithography apparatus, A system in which a computer system is configured to control the operation of a lithographic apparatus. 10. A device manufacturing method using a lithographic process, the device manufacturing method comprising a method according to any one of clauses D5 to D8. 11. A non-transitory computer readable medium program comprising computer readable instructions configured to cause a processor to control a lithographic apparatus according to the method of any one of clauses D5 to D8.

[0292]

[0308] Embodiments include a fifth set of clauses numbered as follows: 1. Controlling a lithography process performed on a first substrate using a reticle in a cryogenic state; Determining one or more performance metrics of the lithography process dependent on inspection of the first substrate; determining a clamping-induced deformation mode of the reticle as a function of one or more performance metrics; A computer system configured to determine and control the application of process modifications to a lithography process performed on a second substrate dependent on the determined clamp-induced deformation mode. 2. The computer system of clause E1, wherein the one or more performance metrics are determined dependent on measurements of characteristics of features formed by a lithographic process on the first substrate. 3. The computer system determining a deformation mode of the overall reticle deformation dependent on one or more performance metrics; Obtaining data regarding expected deformation modes of the reticle in a cold state when the reticle is unclamped; and determining a clamping-induced deformation mode dependent on the determined deformation mode of the overall reticle deformation and an expected deformation mode of the reticle in a cold state when the reticle is unclamped; The computer system of clause E1 or E2, configured to determine clamp-induced deformation modes. 4. The computer system of any one of clauses E1 to E3, wherein the first substrate and the second substrate are from different substrate lots. 5. The computer system is configured to determine, for each of a plurality of lots of substrates, a clamping-induced deformation mode of the reticle in a cold state, such that for each lot of substrates, a clamping-induced deformation mode of the reticle used is determined; The computer system of any one of clauses E1 to E4, wherein the computer system is configured to determine and control the application of process modifications to the lithography process dependent on a plurality of determinations of clamp-induced deformation modes. 6. Performing a lithography process on a first substrate using the reticle in a cooled state; Determining one or more performance metrics of the lithography process dependent on inspection of the first substrate; determining clamp-induced deformation modes of the reticle as a function of one or more performance metrics; and The method includes determining and applying a process modification dependent on the determined clamp-induced deformation mode to a lithography process performed on a second substrate. 7. The method of clause E6, wherein the one or more performance metrics are determined in dependence on measurements of characteristics of features formed by a lithographic process on the first substrate. 8. Determine the clamp-induced deformation mode determining a deformation mode of the overall reticle deformation dependent on one or more performance metrics; Obtaining data regarding expected deformation modes of the reticle in a cold state when the reticle is unclamped; and The method of clause E6 or E7, including determining the clamping-induced deformation mode dependent on the determined deformation mode of the overall reticle deformation and the expected deformation mode of the reticle in a cold state when the reticle is unclamped. 9. The method of any one of clauses E6 to E8, wherein the first substrate and the second substrate are from different substrate lots. 10. Further comprising: performing the method using the reticle in a cold state for each of a plurality of lots of substrates, such that for each lot of substrates, the clamping-induced deformation mode of the reticle used is determined; The method of any one of clauses E6-E9, wherein a process modification to be applied to a lithography process is determined dependent on multiple determinations of clamp-induced deformation modes. 11. A computer system according to any one of clauses E1 to E5, a lithography apparatus, A system in which a computer system is configured to control the operation of a lithographic apparatus. 12. A device manufacturing method using a lithographic process, the device manufacturing method comprising a method according to any one of clauses E6 to E10. 13. A non-transitory computer readable medium program comprising computer readable instructions configured to cause a processor to control a lithographic apparatus according to the method of any one of clauses E6 to E10.

[0293]

[0309] The breadth and scope of an embodiment should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

1. Modeling the shape and / or deformation of the reticle; a computer system configured to control operation of a lithography process using the reticle in dependence on the modeled shape and / or deformation, the computer system comprising: To model the shape and / or deformation of the reticle, the computer system: Acquire initial reference shape data representing the shape of the reticle; acquiring reticle heating calibration (RHC) data including reticle shape data and corresponding reticle alignment (RA) measurement data at different reticle temperatures; generating calibrated reference shape data dependent on the initial reference shape data, the RHC data, and the RA measurement; A computer system configured to model the shape and / or deformation of the reticle based on the calibrated reference shape data.

2. To generate the RHC data, the computer system: acquiring a first data set including reticle shape data and corresponding RA measurement data at different reticle temperatures as the temperature of the reticle decreases during a first period of time; acquiring a second data set including reticle shape data and corresponding RA measurement data at different reticle temperatures as the temperature of the reticle is increased during a second period of time; configured to generate the RHC data in dependence on the first data set and the second data set; 2. The computer system of claim 1, wherein the second period of time is after the first period of time, and a process for reducing stress in the reticle is performed between the first period of time and the second period of time.

3. The computer system of claim 2 , wherein the computer system is configured to determine the RHC data dependent on a comparison of the first data set and the second data set.

4. 10. The computer system of claim 1, wherein the calibrated reference shape data relies on determining the shape of the reticle when the reticle is in a cryogenic state.

5. 2. The computer system of claim 1, wherein the calibrated reference shape data relies on determining the shape of the reticle when the reticle is heated from the cold state of the reticle to a current temperature.

6. 10. The computer system of claim 1, wherein the calibrated reference shape data is dependent upon determining a stress-reduced state of the reticle.

7. Modeling the shape and / or deformation of the reticle; and 1. A method comprising: controlling operation of a lithography process using the reticle in dependence on the modeled shape and / or deformation, the method comprising: modeling the shape and / or deformation of the reticle; Obtaining initial reference shape data representing the shape of a reticle; acquiring reticle heating calibration (RHC) data including reticle shape data and corresponding reticle alignment (RA) measurement data at different reticle temperatures; generating calibrated reference shape data dependent on the initial reference shape data, the RHC data, and RA measurements; and modeling the shape and / or deformation of the reticle in dependence on the calibrated reference shape data.

8. acquiring a first data set including reticle shape data and corresponding RA measurement data at different reticle temperatures as the temperature of the reticle decreases during a first period of time; acquiring a second data set including reticle shape data and corresponding RA measurement data at different reticle temperatures as the temperature of the reticle is increased during a second period of time; generating the RHC data in dependence on the first data set and the second data set; 8. The method of claim 7, wherein the second period of time is after the first period of time, and a process for reducing stress in the reticle is performed between the first period of time and the second period of time.

9. The method of claim 8 , wherein the RHC data is determined dependent on a comparison of the first data set and the second data set.

10. 8. The method of claim 7, wherein the calibrated reference shape data relies on determining the shape of the reticle when the reticle is in a cryogenic state.

11. 8. The method of claim 7, wherein the calibrated reference shape data relies on determining the shape of the reticle as it heats from the cold state of the reticle to a current temperature.

12. The method of claim 7 , wherein the calibrated reference shape data is dependent upon a determination of a stress-reduced state of the reticle.

13. The computer system of claim 1; a lithography apparatus, The computer system is configured to control the operation of the lithographic apparatus.

14. A device manufacturing method using a lithography process, comprising the method of claim 7.

15. A non-transitory computer readable medium program comprising computer readable instructions configured to cause a processor to control a lithographic apparatus according to the method of claim 7.

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