Lithographic apparatus and method of operating same

Abstract

The present disclosure provides a lithographic apparatus and a method of operating a lithographic apparatus. The method comprises the steps of: receiving a reticle assembly comprising a reticle and a pellicle membrane; transporting the mask plate assembly to an exposure tool, and fixing the mask plate assembly on a mask plate carrying table of the exposure tool; determining a scan speed profile based on a risk level associated with the quality of the pellicle membrane; and performing an exposure operation by driving the reticle stage according to the scan speed profile.

Description

Technical Field

[0001] Embodiments of the present application relate to a lithography apparatus and an operating method thereof. Background Art

[0002] The semiconductor integrated circuit (IC) industry has experienced exponential growth. Technological advances in IC materials and design have produced generations of ICs, each smaller and more complex than the previous one. Over the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased, while geometry size (i.e., the size of the smallest component (or line) that can be created using a manufacturing process) has decreased. This scaling down process generally provides benefits by increasing production efficiency and reducing associated costs. However, this scaling down also increases the complexity of IC processing and manufacturing. To achieve these advances, similar developments in IC processing and production are required. For example, there is an increasing need to perform photolithography processes at higher resolutions. Summary of the Invention

[0003] According to one aspect of an embodiment of the present application, a method for operating a photolithography apparatus is provided, comprising: receiving a mask assembly comprising a mask and a pellicle membrane; transporting the mask assembly to an exposure tool, and fixing the mask assembly on a mask carrier of the exposure tool; determining a scanning speed distribution based on a risk level associated with the quality of the pellicle membrane; and performing an exposure operation by driving the mask carrier according to the scanning speed distribution.

[0004] According to another aspect of an embodiment of the present application, a method for operating a lithography device is provided, comprising: receiving a mask assembly, wherein the mask assembly includes a mask and a pellicle membrane; fixing the mask assembly on a mask carrier of an exposure tool; obtaining a pellicle quality index; determining a first scanning speed distribution of the mask carrier based on the pellicle quality index; and performing an exposure operation on a substrate according to the first scanning speed distribution.

[0005] According to another aspect of an embodiment of the present application, a lithography apparatus is provided, comprising: an exposure tool, comprising: a mask carrier operable to fix a mask assembly, wherein the mask assembly includes a mask protected by a pellicle membrane, and the mask carrier is operable to move the mask assembly in a first direction; a substrate carrier operable to fix a substrate, wherein the substrate carrier is operable to move the substrate relative to the mask assembly; and a control unit electrically coupled to the mask carrier; and an inspection tool configured to obtain a deformation level of the thin film, wherein the control unit is configured to determine a scanning speed distribution of the mask carrier based at least on the deformation level of the pellicle membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Various aspects of the present disclosure will be best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be emphasized that, in accordance with standard practice in the industry, various components are not drawn to scale and are used for illustrative purposes only. In fact, the dimensions of various components may be arbitrarily increased or decreased for clarity of discussion.

[0007] Figure 1 is a flow chart illustrating an embodiment of a method of performing acceleration and speed management of a lithography system taking into account diaphragm film quality according to some embodiments of the present disclosure.

[0008] Figure 2 is a schematic diagram of a lithography apparatus according to some embodiments of the present disclosure.

[0009] Figure 3 is a schematic diagram of an exposure tool according to some embodiments of the present disclosure.

[0010] Figure 4A is a schematic cross-sectional view of a reticle assembly according to some embodiments of the present disclosure.

[0011] Figure 4B is a schematic cross-sectional view of a reticle assembly box according to some embodiments of the present disclosure.

[0012] Figure 5 A table showing examples of pellicle membranes according to some embodiments of the present disclosure is shown.

[0013] Figure 6 An embodiment of an Eop trend graph according to some embodiments of the present disclosure is shown.

[0014] Figure 7 A graph showing deformation compared to wafers processed according to some embodiments of the present disclosure is shown.

[0015] Figure 8 is a schematic diagram of an inspection tool according to some embodiments of the present disclosure.

[0016] Figure 9 is a schematic diagram of another inspection tool according to some embodiments of the present disclosure.

[0017] Figure 10 is a schematic diagram of a mask according to some embodiments of the present disclosure.

[0018] Figure 11 is a schematic plan view of a substrate held by a substrate stage according to some embodiments of the present disclosure.

[0019] Figure 12A is a cross-sectional view of an electrostatic chuck and a reticle according to some embodiments of the present disclosure.

[0020] Figure 12B is a schematic diagram of an electrostatic chuck including electrodes according to some embodiments of the present disclosure.

[0021] Figure 12C and Figure 12D is a cross-sectional view of an electrostatic chuck and a reticle according to some embodiments of the present disclosure.

[0022] Figures 13A-13L The diagram schematically depicts exposure operations performed on some illumination areas on a substrate according to some embodiments of the present disclosure.

[0023] Figure 14 A first scanning velocity profile is shown according to some embodiments of the present disclosure.

[0024] Figure 15 A schematic diagram of a lithography system according to some embodiments of the present disclosure is shown.

[0025] Figure 16 is a flow chart illustrating a method for operating an exposure tool according to some embodiments of the present disclosure.

[0026] Figure 17 is a flow chart illustrating a method for operating an exposure tool according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0027] The following disclosure provides many different embodiments or examples for implementing the different features of the present disclosure. Specific embodiments or examples of components and arrangements are described below to simplify the present disclosure. Of course, these are merely examples and are not intended to be limiting. For example, in the following description, forming a first component above or on a second component may include an embodiment in which the first component and the second component are directly in contact with each other, and may also include an embodiment in which an additional component may be formed between the first component and the second component so that the first component and the second component may not be in direct contact. In addition, the present disclosure may repeat reference numbers and / or letters in various examples. This repetition is for the purpose of simplicity and clarity and does not itself indicate the relationship between the various embodiments and / or configurations discussed.

[0028] Furthermore, for ease of description, spacing terms such as "below," "beneath," "lower," "above," "upper," etc., may be used herein to describe the relationship of one element or component to another element or component as illustrated in the figures. Spacing terms are intended to encompass different orientations of the device in use or during operation in addition to the orientations depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and spacing descriptors used herein should be interpreted accordingly.

[0029] As used herein, the terms "first," "second," and "third" describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, or sections should not be limited by these terms. These terms may only be used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Unless the context clearly indicates otherwise, the terms "first," "second," and "third" as used herein do not imply a sequence, order, or importance.

[0030] Although the numerical ranges and parameters describing the broad scope of the present disclosure are approximate, the numerical values ​​described in the specific examples are reported as accurately as possible. However, any numerical value inherently contains certain errors, which are inherently caused by the normal deviation found in the corresponding test measurements. In addition, as used herein, the terms "substantially", "approximately" or "approximately" generally mean within a value or range that can be considered by a person of ordinary skill in the art (for example, within 10%, 5%, 1% or 0.5% of a given value or range). Alternatively, the terms "substantially", "approximately" or "approximately" mean within an acceptable standard error range of the mean value. It will be understood by those of ordinary skill in the art that acceptable standard errors may vary depending on the technology. Except in the operating / working examples, or unless otherwise expressly provided, all numerical ranges, amounts, values ​​and percentages disclosed herein (such as material amounts, durations, temperatures, operating conditions, amount ratios, etc.) should be understood as "substantially", "approximately" or "approximately" in all cases. Therefore, unless otherwise stated, the numerical parameters proposed in this disclosure are approximate values ​​that can be changed as needed. At the very least, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Ranges may be expressed herein as from one endpoint to the other or between two endpoints. Unless otherwise indicated, all ranges disclosed herein include the endpoints.

[0031] In photolithography, a photoresist layer is formed on a substrate and an exposure operation is performed on the photoresist layer through a mask. A mask with a desired pattern is mounted on a mask carrier; the mask may also be referred to as a mask in this article. During the exposure operation, the mask carrier is operable to move the mask in one or more directions as needed so that the mask is properly aligned with respect to the substrate. Therefore, electromagnetic radiation directed at the mask pattern can be projected onto selected areas of the photoresist layer. The electromagnetic radiation may cause a chemical transformation in the selected areas of the photoresist layer. In a subsequent development step, the selected areas or non-selected areas can be removed from the substrate. In this way, the pattern of the mask can be transferred to the photoresist layer, thereby forming a patterned photoresist layer. The substrate can then be further processed (for example, removal, deposition, doping, etc.) by the patterned photoresist layer to form a patterned layer (corresponding to the pattern of the mask) in or on the substrate.

[0032] It is desirable for the pattern of the reticle to have minimal defects to improve production yield. Preventing particles present in the environment from settling on the reticle can be challenging. Therefore, a pellicle membrane (or simply a pellicle) is sometimes used to cover the reticle. The pellicle can be located directly below the reticle and allows radiation, such as extreme ultraviolet (EUV) light, to pass through. Flexure, such as deformation of the pellicle membrane (e.g., sagging outward), can occur. This deformation can be caused by, for example, gravity, the weight of foreign matter deposited on the pellicle membrane, and / or conditions (e.g., pressure) that cause the reticle assembly, including the pellicle, to move.

[0033] Due to the need for high throughput, a reticle stage (also known as a mask chuck or stage) moves the reticle at a constant speed along the scan direction during photolithography exposure operations. This high speed, and the acceleration of the reticle to that speed, can exert stress on the pellicle and cause deformation, including damage such as cracking.

[0034] Some embodiments of the present disclosure provide a lithography apparatus and method for operating the same. The apparatus includes a control unit configured to provide a scanning velocity profile, including an acceleration management plan, to the reticle stage based on various factors, including the deformation range of the pellicle membrane. Consequently, image distortion during exposure can be effectively reduced, and the service life of the pellicle membrane can be extended. Advantages of some embodiments include cost savings from reassembling the reticle due to damage to the reticle and / or pellicle, and improved scanner productivity through acceleration and velocity management.

[0035] Figure 11 is a block diagram of a method 100 for performing acceleration and velocity management of a lithography system and reticle stage, specifically considering diaphragm film quality. Method 100 includes block 102, where an initial state index is obtained. In one embodiment, the obtained state index includes one or more of energy on power (EOP) state, wafer movement (WM) state, pellicle type (e.g., diaphragm film design details), initial state of the diaphragm film (e.g., position), and / or other suitable indices. The state index can be obtained from online process data, simulation data, modeling data, experimental data, design databases, process data, reticle data, etc. In one embodiment, obtaining the pellicle state index includes block 104. In block 104, a sag test is performed. The pellicle film can be subjected to a sag test to determine its state. The sag test can be an empirical test that determines the sag value (e.g., displacement distance in microns) of the pellicle film. Blocks 102 and 104 can be performed simultaneously or in an alternating sequence. Method 100 then proceeds to block 106, where a scan velocity profile including an acceleration management plan is generated and / or implemented based on the results of blocks 102 and / or 104. Method 100 then proceeds to block 108, where the wafer is exposed in a photolithography process, thereby implementing the scan velocity profile including the acceleration management plan. In one embodiment, implementation of the plan allows for avoiding pellicle damage, such as cracking. Each of these blocks will be discussed in more detail below.

[0036] Figure 2 2 is a schematic diagram of a lithography apparatus 200 according to some embodiments of the present disclosure. The lithography apparatus 200 includes, for example, an exposure tool 202, an inspection tool 203, and a transfer robot 204. In some embodiments, the lithography apparatus 200 is installed in a clean room. Air controlled to a predetermined temperature circulates in the clean room to keep the internal temperature of the clean room approximately constant or within a predetermined range. Reference atmosphere. In one embodiment, the lithography apparatus 200 can be connected to a load lock chamber (see Figure 15 ), the load lock chamber is used to load the mask assembly 302 (e.g. Figure 4A ) is loaded into and unloaded from the lithographic apparatus 200. The exposure tool 202 is housed in an exposure chamber (not separately shown), and in one embodiment, the inspection tool 203 is located within an inspection chamber (not separately shown). In other embodiments, the inspection tool 203 is separate and distinct from the exposure tool 202 (e.g., offline). The transfer robot 204 loads and unloads the reticle assembly 302 and transports the reticle assembly 302 between the exposure tool 202 and the inspection tool 203. In some embodiments, the inspection tool 203 can be integrated into the exposure tool 202 to reduce the delivery time of the reticle assembly 302 between the exposure tool 202 and the inspection tool 203.

[0037] Figure 3 FIG2 is a schematic diagram of an exposure tool 202 according to some embodiments of the present disclosure. Exposure tool 202 can be used, for example, in the manufacture of integrated circuits. Reticle assembly 302 can be used to provide a desired pattern 302P to be formed on a material layer of the integrated circuit. During an exposure operation, reticle assembly 302 is illuminated by electromagnetic radiation ER_1, where pattern 302P of reticle assembly 302 reflects and patterns electromagnetic radiation ER_1 to form patterned electromagnetic radiation ER_2. Patterned electromagnetic radiation ER_2 is directed onto photoresist layer 322 disposed on substrate 320.

[0038] In some embodiments, exposure tool 202 includes a radiation source 324, a reticle stage 304, a substrate stage 306, an illumination optics module 308, a projection optics module 310, a detector 312, a database 316, and a control unit 314. Radiation source 324 is configured to generate electromagnetic radiation ER_1. In some embodiments, reticle stage 304 secures reticle assembly 302 and provides for precise positioning and movement of the reticle assembly during exposure operations. In some embodiments, substrate stage 306 supports substrate 320 and is capable of moving substrate 320 relative to reticle assembly 302. In some embodiments, illumination optics module 308 is configured to direct electromagnetic radiation ER_1 generated by radiation source 324 toward reticle assembly 302. In some embodiments, projection optics module 310 directs patterned electromagnetic radiation ER_2, which carries an image of a pattern on reticle assembly 302, onto photoresist layer 322.

[0039] In some embodiments, detector 312 can provide information about electromagnetic radiation ER_1 and / or patterned electromagnetic radiation ER_2 to control unit 314. In some embodiments, database 316 contains data for operating exposure tool 202 and data associated with reticle assembly 302 and substrate 320. In some embodiments, control unit 314 is electrically coupled to Figure 3 3. The reticle stage 304, the detector 312, the database 316, and the inspection tool 203 are shown. The control unit 314 can receive information from the radiation source 324, the reticle stage 304, the substrate stage 306, the detector 312, the database 316, and the inspection tool 203, and send control data to the radiation source 324, the reticle stage 304, and the substrate stage 306. In some embodiments, the control unit 314 is configured to control the scanning speed of the reticle stage 304 based on the information provided by the radiation source 324, the detector 312, the database 316, and the inspection tool 203, and the details of the control will be discussed below.

[0040] Radiation source 324 can be any suitable light source, such as an extreme ultraviolet (EUV) source. The EUV source can generate EUV radiation having a wavelength between 1 nm and approximately 100 nm. In some embodiments, the EUV source generates EUV radiation having a wavelength centered around approximately 13.5 nm. The EUV radiation can be generated using a pulsed waveform, and the radiation energy can be represented by the total energy of the EUV pulse applied during the entire exposure operation in joules.

[0041] Because gas molecules tend to absorb EUV radiation, the optical path through which the EUV radiation passes is maintained in a vacuum environment to prevent loss of EUV intensity. In some embodiments, when exposure tool 202 uses EUV radiation, exposure tool 202 is housed in and operates in a vacuum environment. In some embodiments, when exposure tool 202 includes an EUV source, reticle 302 is a reflective reticle. In other embodiments, radiation source 324 may include a light source selected from the group consisting of an ultraviolet (UV) source, a deep ultraviolet (DUV) source, and an X-ray source. Radiation source 324 may alternatively include a particle source selected from the group consisting of an electron beam (E-beam) source, an ion beam source, and a plasma source.

[0042] The reticle assembly 302 is held on the reticle stage 304. In some embodiments, the reticle assembly 302 is held on the reticle stage 304 by electrostatic forces. For example, the reticle stage 304 includes an electrostatic chuck 304e to hold the reticle assembly 302 in place during the exposure operation. Figures 12A-12D The chuck is discussed in more detail below. Reticle stage 304 is operable to move reticle assembly 302 in at least one scanning direction. Reticle stage 304 also has a fine adjustment mechanism for positioning reticle assembly 302 relative to substrate 320 for precise exposure. In some embodiments, reticle stage 304 is designed and operable for translation, rotation, and / or tilt motion.

[0043] In some embodiments, reticle 302 and substrate 320 move synchronously during exposure operations.Substrate stage 306 can have a movement speed proportional to the scanning speed of reticle stage 304.

[0044] During an exposure operation, a portion of reticle assembly 302 is illuminated by electromagnetic radiation ER_1. Illumination optics module 308 can be used to uniformize the intensity distribution of electromagnetic radiation ER_1. Illumination optics module 308 can be used to shape the profile of electromagnetic radiation ER_1 emitted from radiation source 324. For example, when electromagnetic radiation ER_1 passes through illumination optics module 308, it is shaped into a designed profile. As a result, patterned electromagnetic radiation ER_2 has a corresponding profile. In embodiments where exposure tool 202 includes an EUV source, illumination optics module 308 includes various reflective optical components, such as a plane mirror and / or a plurality of mirrors including reflective surfaces having convex or concave spherical or aspherical shapes.

[0045] Projection optics module 310 directs patterned electromagnetic radiation ER_2, bearing an image of the illuminated portion of reticle assembly 302, onto photoresist layer 322. Projection optics module 310 can have a magnification factor (e.g., ¼). The magnification factor refers to the ratio of the size (e.g., area) of electromagnetic radiation ER_1 at reticle assembly 302 to the corresponding size of patterned electromagnetic radiation ER_2 at substrate 320. Projection optics module 310 can have the same magnification factor in the X and Y directions. To achieve synchronized movement of reticle stage 304 and substrate stage 306 during exposure operations, when the magnification factor of projection optics module 310 is ¼, the movement speed of substrate stage 306 during exposure operations is ½ the scanning speed of reticle stage 306. In embodiments where exposure tool 202 includes an EUV source, projection optics module 310 includes various reflective optical components, such as a plane mirror and / or a plurality of mirrors including reflective surfaces having convex and concave spherical or aspherical shapes.

[0046] Figure 4A is a schematic cross-sectional view of a mask assembly 302 according to some embodiments of the present disclosure. The mask assembly 302 may be similar to the mask assembly 302 described above. Figure 3 The discussion is basically similar. Figure 4A Reticle assembly 302 includes reticle 402 and pellicle 404. Pattern 302P is formed on the surface of reticle 402. When reticle 402 and pellicle 404 are in good condition, reticle 402 can be used to reproducibly imprint hundreds or thousands of substrates 320. Despite efforts to maintain a clean environment within exposure tool 202, particles may still be present within lithographic apparatus 200. Particles that land on reticle 402 may adversely affect pattern 302P carried by patterned electromagnetic radiation ER_2 and transferred to substrate 320, potentially leading to yield and quality issues. To protect reticle 402 from particle contamination, the pattern of reticle 402 is protected by pellicle 404.

[0047] The pellicle 404 includes a frame 404f together with the pellicle membrane, and the frame 404f holds the pellicle membrane in place. The frame 404f can be set at the edge portion of the pellicle 404. The pellicle membrane can be adhered to the frame 404f with glue or other adhesives. The frame 404f can be any material with high mechanical strength, low dust absorption tendency and light weight. Hard plastic and materials such as aluminum or aluminum alloys can be suitable materials for the frame 404f. The pellicle 404 is designed to have high transmittance to electromagnetic radiation ER_1 and low reflectivity to electromagnetic radiation.

[0048] The pellicle 404 is attached to the reticle 402 via a frame 404f and surrounds the pattern on the reticle 402. Therefore, contaminants that would otherwise be deposited on the pattern 302P of the reticle 402 are blocked by the pellicle 404. In addition, the frame 404f is used to position the pellicle 404 at a sufficient defocus distance from the pattern so that any particles on the pellicle 404 are out of focus during the exposure operation and are not projected onto the target substrate.

[0049] To minimize EUV transmission losses, it may be desirable to make pellicle 404 as thin as possible. In some embodiments, the thickness of pellicle 404 ranges from approximately 15 nm to approximately 50 nm. Pellicle 404 may be a multi-layer structure. In some embodiments, the multi-layer structure is made of a combination of different materials selected for specific purposes (e.g., heat dissipation, strength, uniformity, durability, stability, etc.) and arranged in a desired order.

[0050] Reference Figure 4B , a cross-sectional view of a reticle cassette 406 is shown. The reticle cassette 406 provides storage, transportation, and protection for a reticle (e.g., reticle assembly 302) when loaded into a lithography system such as the lithography apparatus 200. The reticle cassette 406 includes two boxes, an inner box 406A (also referred to as an inner box (EIP)) and an outer box 406B (also referred to as an outer box (EOP)). A restraining mechanism 408 holds the reticle assembly 302. Although not shown, the reticle assembly is placed face down and includes a pellicle arranged on the patterned surface as described above. For example, the pellicle is disposed between the restraining mechanisms 408 below the reticle assembly 302. The restraining mechanisms 408 can be clamps, grooves, pins, fixed blocks, springs, or other suitable devices. An interior space 410 surrounds the reticle assembly 302. The inner box 406A can be made of a metal material such as stainless steel, and the outer box 406B can be made of plastic.

[0051] Figure 5Multiple examples of pellicle membranes according to some embodiments are shown, such as pellicle membrane 404. For ease of reference, exemplary embodiments or exemplary stacks are titled "Type" in the first row of the table. Type 1 pellicle is a five-layer structure, including, from bottom to top, a first silicon nitride (Si3N4) layer, a polysilicon (p-Si) layer, a second silicon nitride layer, a molybdenum (Mo) layer, and a ruthenium (Ru) layer. The polysilicon layer serves as the core layer of the pellicle membrane. The first and second silicon nitride layers can be used to protect the core layer (i.e., the polysilicon layer). The molybdenum layer can support thermal stability, mechanical stability, and chemical durability while having a high EUV transmittance of approximately 90% or more. According to some embodiments, the ruthenium layer has the advantages of achieving the desired light transmission performance and heat dissipation. In some embodiments, the first silicon nitride layer can also be used as an etch stop layer during the manufacturing process of the pellicle membrane, and the second silicon nitride layer can also be used as a diffusion barrier layer between the molybdenum layer and the polysilicon layer.

[0052] The polysilicon layer can have a first thickness that is the maximum thickness among the pellicle membrane layers. The first thickness can be, for example, equal to or less than approximately 40 nm. The first silicon nitride layer can have a second thickness that is less than the first thickness. In one embodiment, the first silicon nitride layer can have a second thickness that is substantially less than the first thickness. Here, the term "substantially less" means at least ten times less. According to some embodiments, the second silicon nitride layer has a third thickness that is less than the second thickness, the molybdenum layer has a fourth thickness that is between the first and second thicknesses, and the ruthenium layer has a fifth thickness that is less than the third thickness. The Type 1 pellicle membrane has an EUV transmittance of approximately 80-85% and an EUV reflectance of approximately 0.05%-0.08%.

[0053] The Type 2 pellicle includes the same stack structure as the Type 1 pellicle. The stack structure of the Type 2 pellicle may be thinner than that of the Type 1 pellicle. For example, in the Type 2 pellicle, the thickness of the polysilicon layer is less than the first thickness of the Type 1 pellicle, thereby increasing EUV transmittance (e.g., from approximately 83% to approximately 88%). The EUV reflectivity of the Type 2 pellicle is approximately 0.03%-0.07%. Furthermore, in the Type 2 pellicle, the thicknesses of the first silicon nitride layer, the second silicon nitride layer, and the ruthenium layer are all less than the corresponding second, third, and fifth thicknesses of the Type 1 pellicle. Furthermore, the thickness of the molybdenum layer of the Type 2 pellicle is greater than the fourth thickness of the Type 1 pellicle.

[0054] For Type 2 and Type 3 pellicles, the first and second nitride layers are N-rich silicon nitride (SiNx) layers. The nitrogen-rich layers are used to increase the mechanical rigidity of the pellicle. In some embodiments, the first silicon nitride layer can have a second thickness, and the second silicon nitride layer can have a third thickness, both of which are Type 1 pellicle thicknesses. Type 3 pellicles can have an EUV transmittance of approximately 83%-88% and an EUV reflectivity of approximately 0.03%-0.07%.

[0055] For Type 3 and Type 4 pellicles, the ruthenium layer is replaced with a ruthenium niobium (RuNb) layer to meet the critical dimension (CD) requirements of the pellicle. The EUV transmittance of the Type 4 pellicle is approximately 84%-88%, and the EUV reflectivity is approximately 0.03%-0.07%.

[0056] The Type 5 pellicle is a three-layer structure comprising, from bottom to top, a first silicon nitride layer, a molybdenum silicide (MoSi) layer, and a second silicon nitride layer. The molybdenum silicide layer serves as the core layer of the pellicle, and the first and second silicon nitride layers serve to protect the molybdenum silicide layer. The sixth thickness of the molybdenum silicide layer is less than the first thickness of the polysilicon layer in the Type 1 pellicle, thereby increasing EUV transmittance (e.g., from approximately 86% to approximately 90%). In some embodiments, the sixth thickness is less than approximately half of the first thickness. The first and second silicon nitride layers can have substantially equal thicknesses, which are slightly greater than the thickness of the first silicon nitride layer in the Type 1 pellicle. The EUV reflectivity of the Type 5 pellicle is approximately 0.02%-0.06%.

[0057] The Type 6 pellicle includes a four-layer structure. Compared to the Type 5 pellicle, the Type 6 pellicle also includes a molybdenum disilicide (MoSi2) layer inserted between the molybdenum silicide layer and the second silicon nitride layer, and the thickness of the molybdenum silicide (MoSi) layer is thinner than that of the Type 5 pellicle. The molybdenum disilicide (MoSi2) layer can be used as a heat dissipation layer to improve the heat dissipation effect, thereby ensuring the performance of the pellicle. More specifically, the heat dissipation layer suppresses the temperature increase of the film surface during the exposure operation, thereby reducing the temperature and improving the thermal performance of the pellicle. The EUV transmittance of the Type 6 pellicle is approximately 86%-90%, and the EUV reflectivity is approximately 0.02%-0.06%.

[0058] The above and Figure 5Exemplary thicknesses of the stacks shown include: Type 1, 2.0-3.0 nanometers (nm) of Ru layer, 3.5-4.5 nm of Mo layer, 34-38 nm of pSi and / or 3-3.5 nm of SiN; Type 2, 1.5-2.5 nm of Ru layer, 4.0-5.0 nm of Mo layer, 27-32 nm of pSi and / or 2-2.5 nm of SiN; Type 3, 1.7-2.5 nm of Ru layer, 4.0-5 nm of Mo layer, 26-33 nm of pSi and / or 2.5-3.5 nm of SiN; Type 4, 1.5-3 nm of Ru layer, 4.0-5.0 nm of Mo layer, 27-31 nm of pSi and / or 2.5-3.5 nm of SiN; Type 5, 15-35 nm of MoSi and / or 15-35 nm of SiN 3.5nm-4.5nm; Type 6, MoSi13nm-18nm and / or SiN 3nm-4nm (MoSi2 1:2, MoSi 1:1). These thicknesses are merely exemplary and not limiting unless specifically listed in the following disclosure.

[0059] As discussed above, the pellicle membrane is flexible and has a tendency to deform when exposed to pressure gradients, mechanical vibrations, or mechanical stresses during use or transportation. For example, as the amount of particles attached to the pellicle membrane 404 increases, the pellicle membrane 404 may begin to deform downward due to the weight of the particles. The pellicle membrane 404 may also sag or deform due to gravity. Sagging and its measurement are discussed further below. It is worth noting that the flexibility and sagging / deformation of the pellicle membrane depends on the composition and thickness of the stack. Therefore, a pellicle membrane such as Figure 5 The provided stacking information is included in a database 316 that is available to the controller 314 .

[0060] It should be noted that during the exposure operation, as in Figure 3 In the example discussed in the context of , electromagnetic radiation ER_1 provided by radiation source 324 is guided through illumination optical module 308 and pellicle membrane 404 and reaches mask 402. Patterned electromagnetic radiation ER_2 reflected by the pattern passes through pellicle membrane 404 and is guided to substrate 320 through projection optical module 310. Pellicle membrane 404 can absorb part of the energy of electromagnetic radiation ER_1 and patterned electromagnetic radiation ER_2. The absorbed energy may cause heat energy to be generated on pellicle membrane 404. As a result, the material layer of pellicle membrane 404 may deform or chemically change (e.g., oxidize) due to heat accumulation. When heat-induced deformation occurs, pellicle membrane 404 may lose elasticity or become brittle. As with stacking information, information about the deformation or chemical change of the material layer (e.g., generated by experiments or modeling) may also be provided in database 316.

[0061] During exposure operations, the movement of the reticle stage 304 affects the deformation of the pellicle membrane 404. More specifically, it may be desirable to move the reticle assembly 302 by the reticle stage 304 at high speeds to achieve high throughput. This high speed may introduce undesirable airflow onto the pellicle membrane 404, thereby increasing the likelihood or extent of deformation of the pellicle membrane 404. If the deformation of the pellicle membrane 404 exceeds a tolerable level, the pellicle membrane 404 may break, resulting in damage or contamination of unprotected reticles or other components of the exposure tool 202 (e.g., mirrors of the illumination optics module 308 and projection optics module 310). This may cause downtime in the manufacturing process. Furthermore, the acceleration of the reticle before and between scans (as described below) can affect the deformation of the pellicle membrane 404. Specifically, the deformation of the pellicle membrane 404 may be affected by the acceleration of the reticle stage 304 during the photolithography process, including, for example, acceleration and deceleration relative to the scanning speed maintained in the feature area of ​​the reticle 402. Therefore, in some embodiments, Figure 2 The illustrated inspection tool 203 is configured to measure the level of deformation of the pellicle membrane 404 , as described below.

[0062] The detector 312 is, for example, arranged adjacent to the mask assembly 302. The detector 312 is configured to detect the energy of the patterned electromagnetic radiation ER_2 and provide the detection result to the control unit 314. Figure 3 Only one detector 312 is shown adjacent to pellicle 404, but any suitable number of detectors 312 may be included in exposure tool 202 and positioned at any suitable location near the optical path of patterned electromagnetic radiation ER_2. It should be noted that the location of detector 312 may vary outside the path of ER_2. Furthermore, in some embodiments, detector 312 may be omitted, and the energy may be determined from other sources, such as simulations, modeling, experimental results, calculations from other processes (e.g., photoresist development), and / or other suitable metrics.

[0063] During an exposure operation, radiation source 324 is configured to generate electromagnetic radiation ER_1 having a radiation energy per unit area (also referred to as "process energy," "power energy," or Eop). The provided radiation energy is substantially constant during the exposure operation, while the patterned electromagnetic radiation ER_2 has an exposure energy that is affected by its interaction with components, including pellicle 404, and thus depends on the quality of pellicle 404 (e.g., reflectivity, deformation). More specifically, during EUV irradiation, pellicle 404 may absorb some of the energy of electromagnetic radiation ER_1 and patterned electromagnetic radiation ER_2. The absorbed energy causes pellicle 404 to generate waste heat. Due to the heat, a thin oxide film may form on the surface of the silicon-based layer in pellicle 404. When reticle assembly 302 is repeatedly used, the oxide film may thicken with each exposure operation. The oxide film reduces the transmittance of pellicle 404, thereby reducing the transmitted exposure energy.

[0064] During an exposure operation, the pattern of the mask 402 is transferred to the photoresist layer 322 by exposing portions of the photoresist layer 322 to patterned electromagnetic radiation ER_1, rendering the exposed portions soluble or insoluble in a developer solution. The soluble portions are then removed, thereby forming a patterned photoresist layer on the substrate 320. The substrate 320 can be further processed by the patterned photoresist layer 322 to form desired device features in or on the substrate 320. Therefore, the accuracy of the patterned photoresist layer plays a key role in device performance. Photoresist layer 322 irradiated with patterned electromagnetic radiation ER_2 having a reduced exposure energy can form a patterned photoresist layer having a pattern that does not meet specifications (e.g., line width, line spacing, sidewall angle, etc.). Therefore, it is desirable to maintain the exposure energy required to induce a stable chemical transformation in the exposed areas of the photoresist layer 322 so that the patterned photoresist layer can be manufactured with a high degree of quality control in terms of pattern shape accuracy and uniformity.

[0065] In some embodiments, the control unit 314 is further configured to control the radiation energy of the radiation source 324 to tune the exposure energy of the patterned electromagnetic radiation ER_2. For example, the control unit 314 can be configured to control the radiation energy based on the detection results provided by the detector 312. The radiation energy (Eop) can be proportional to the supply power of the radiation source, and the control unit 314 can control the radiation energy by increasing or decreasing the supply power.

[0066] According to some embodiments, radiation source 324 is configured to generate electromagnetic radiation ER_1 having an initial level of radiation energy. The initial level is determined based on the pattern of photoresist layer 322, pellicle 404, reticle 402, and / or other suitable metrics, and is suitable for providing a precise pattern exposure on photoresist layer 322.

[0067] According to one embodiment, in another exposure operation in which an oxide film is at least partially formed on the pellicle membrane 404 or the pellicle membrane 404 is otherwise degraded, the radiation source 324 is configured to generate electromagnetic radiation ER_1 having an adjusted (increased) level of radiation energy. The adjusted level is determined based on the detection results provided by the detector 312 and / or based on input parameters of the mask stack composition, the number of wafer runs, pattern density or criticality and / or other suitable inputs. The control unit 314 is also configured to determine the adjusted level of radiation energy in response to the determination. The adjusted level can be the difference between the adjusted level and the initial level. In some embodiments, the adjusted level is expressed as a percentage of the radiation and exposure energy. Figure 6 is a schematic graphical representation of energy increases as the number of wafers processed increases. In one embodiment, an energy percentage adjustment is determined, and in some embodiments, the controller 314 determines that the pellicle 404 needs to be replaced after a specific threshold (e.g., 5%-5.5%) of the Eop percentage adjustment is reached. The energy adjustment percentage, Eop, is one of the pellicle quality indices used to determine scan speed plans, including acceleration profile management. For example, as described above, the percentage increase describes an increase in pellicle risk.

[0068] As described above, in addition to the percentage adjustment of energy collected by controller 314 and database 316, controller 314 and database 316 also store and / or collect other pellicle indices that indicate the quality and life of the pellicle. Database 316 may include information about the usage history of reticle 402, the composition of pellicle sheet 404, the usage history of pellicle sheet 404, the deformation level of pellicle sheet 404 provided by an external inspection tool (e.g., device 203), etc. These are all pellicle indices that indicate the quality of the film and are useful for determining the quality of the pellicle. Figure 7 is a trend graph showing deformation or sagging measurements (e.g., sagging values) in microns provided by inspection tools for various reticle assemblies 302 and pellicle membranes 404. In one embodiment, controller 314 obtains the deformation measurements to determine whether pellicle membranes 404 need to be replaced and / or to determine a pellicle quality index used to determine a scan speed plan including acceleration profile management.

[0069] In some embodiments, the control unit 314 is configured to determine the risk level based on one or more received indices, including the indices described above. In one embodiment, the risk level of the pellicle 404 is determined based on the level of deformation (e.g., sagging) of the pellicle 404. Further considerations include the movement speed of the reticle stage 304 previously executed and subsequently planned (e.g., scan speed plan). Another consideration may be the level of regulation of the radiation energy, such as Figure 6Another consideration can be a pellicle index, such as the composition of the pellicle membrane 404. One or more of these factors (pellicle indices) can be used to assign a risk level. The risk level can correspond to an action appropriate for the pellicle, such as requiring replacement, continued use at a standard scanning speed and acceleration profile, or continued use at a modified scanning speed and acceleration profile (e.g., reduced acceleration rate). Control unit 314 can control the scanning speed and acceleration of reticle stage 220 based on the risk level associated with pellicle membrane 404.

[0070] As described above, control unit 314 can receive deformation information (e.g., sagging values) from inspection device 203. That is, in one embodiment, reticle assembly 302 is provided to inspection device 203, which measures the deformation or sagging of pellicle membrane 404. This measurement can be transmitted to controller 314 and / or stored in database 316. In one embodiment, reticle assembly 302 is provided to inspection device 203 using processor 204 at each interval during which wafers are produced using a reticle 402 of reticle assembly 302. For example, a program can be established to perform measurements after exposing a given number of wafers.

[0071] Figure 8 and Figure 9 is a schematic cross-sectional view of an embodiment of a deformation measurement device (such as inspection device 203). Figure 8 An embodiment of performing pellicle deformation measurement while positioned on a reticle is shown; Figure 9 An embodiment of performing pellicle deformation measurement while being disassembled from a reticle is shown. Figure 8 and Figure 9 The inspection tool 203 includes an inspection chamber 800, a holding structure 802, a pressure gauge 804, and an inspection unit 806. The inspection chamber 800 includes a gas inlet 808A for receiving a supply gas and an exhaust port 808B for exhausting the supply gas from the inspection chamber 800. For example, the supply gas is extremely clean dry air (XCDA) gas. The XCDA gas may be useful for reducing humidity in the inspection chamber 800.

[0072] The retaining structure 802 can extend from the inner wall of the inspection chamber 800 and can be used to hold the pellicle membrane 404 to be inspected. In some embodiments, when the pellicle 114 or the mask assembly 302 is attached to the retaining structure 802, the inspection chamber 800 is separated by the pellicle 404 or the mask assembly 302 and includes an upper space and a lower space. The upper and lower spaces are airtight spaces. The pressure difference between the upper and lower spaces may cause the pellicle membrane 404 to deform, wrinkle, break or be damaged in other ways. In some embodiments, the pressure gauge 804 monitors the pressure of the upper and lower spaces of the inspection chamber 800. In some embodiments, the pressure of the inspection chamber 800 is regulated by a pump (not shown) connected to the gas outlet 808B. The pressure gauge 804 and the pump are used to equalize the pressure of the upper and lower spaces.

[0073] In some embodiments, inspection of the pellicle 404 is performed by directing an inspection (light) beam to the pellicle 404 in a darkroom and visually detecting light scattered from deformed areas and / or contaminants. In some embodiments, the inspection unit 806 includes an optical emitter 810 and one or more optical detectors 812. The optical emitter 810 generates an inspection beam I B and will check beam I B Projected onto the pellicle 404. In some embodiments, the inspection beam I B The optical transmitter 810 may include a laser diode to project a laser beam having a relatively small projected area onto the pellicle 404. B There is a wavelength range, and the pellicle membrane 404 can be transparent within the wavelength range.

[0074] The optical detector 812 is checking the beam I B The scattered light is collected after interacting with the pellicle 404. In some embodiments, the optical detector 812 detects the scattered light beam from the illuminated pellicle 404 or matter (such as particles) present on the pellicle 404. Figure 8 In the inspection tool 203 shown, the optical detector 812 also collects the reflected light beam from the reticle 402. The inspection unit 806 can generate an inspection result based on the scattered light. The optical detector 812 can include, but is not limited to, a complementary metal oxide semiconductor (CMOS) sensor or a charge coupled device (CCD).

[0075] Inspection unit 806 may perform an inspection on one or more areas of pellicle membrane 404 and generate an inspection result (e.g., a sagging value) indicating a deformation level of pellicle membrane 404 based on the detected scattered light. Control unit 314 may receive the inspection result and be configured to determine a risk level of rupture of pellicle membrane 404 based on the inspection result.

[0076] As the pellicle sheet 404 undergoes repeated use (e.g., through repeated exposure operations), the deformation level (see arrows) of the pellicle sheet 404 may gradually increase. A greater degree of deformation of the pellicle sheet 404 may cause the optical detector 812 to detect a greater amount of scattered light beams.

[0077] Therefore, the control unit 314 can be configured to collect information from multiple sources including the database 316, the inspection equipment 203, and the exposure tool 202. Based on the collected information, referred to herein as the pellicle quality index (e.g., Eop adjustment, sagging value, pellicle stack composition, original or previous state of the pellicle, exposed wafer), it is used to determine several (three as an example only) risk levels based on the deformation level of the pellicle film 404 and the adjustment level of the radiation energy, the details of which will be discussed below.

[0078] In one example, in response to finding that the pellicle membrane 404 includes a deformation level of less than about 10 μm and a radiation energy adjustment level (e.g., Eop percentage adjustment) of less than about 3%, the control unit 314 is configured to determine that the pellicle membrane 404 is at a low risk of breakage level during the exposure operation. In some embodiments, the pellicle membrane 404 at a low risk of breakage level can be used for subsequent exposure operations including about 1,000 to about 10,000 substrates or wafers. The control unit 314 can be configured to move the reticle stage 304 using a standard scanning speed profile. In one embodiment, when the pellicle membrane 404 is determined to be at a low risk of breakage level, the controller 314 can implement a uniform speed.

[0079] In another example, in response to finding that the pellicle membrane 404 includes a deformation level ranging from about 10 μm to about 20 μm and a radiation energy adjustment level (e.g., Eop percentage adjustment) ranging from about 3% to about 4.5%, the control unit 314 is configured to determine that the pellicle membrane 404 is at a medium risk of rupture during the exposure operation. In some embodiments, the pellicle membrane 404 at the medium risk of rupture level can be used in subsequent exposure operations having about 500 to about 5,000 substrates. The control unit 314 can be configured to move the reticle stage 304 using a standard scanning speed profile. In one embodiment, when the pellicle membrane 404 is determined to be at a medium risk of rupture, the controller 314 can implement a uniform speed. In one embodiment, the acceleration profile can be slightly adjusted (e.g., reduced).

[0080] In another example, in response to finding that pellicle 404 includes a deformation level between approximately 20 μm and approximately 30 μm, and the level of adjustment of the radiation energy (e.g., Eop percentage adjustment) is greater than approximately 4.5%, the control unit 314 is configured to determine that pellicle 404 is at a high risk of rupture during an exposure operation. In some embodiments, pellicle 404 at a high risk of rupture can be used in subsequent exposure operations having approximately 100 to approximately 1,000 substrates. The control unit 314 can be configured to move the reticle stage 304 using a reduced scanning velocity profile that includes reduced acceleration management. In one embodiment, when it is determined that pellicle 404 is at a high risk of rupture, the control unit 314 can be configured to move the reticle stage 304 using a non-uniform velocity. In one embodiment, the acceleration profile can be adjusted more (e.g., reduced). The control unit 314 can provide an alarm or other indication of the pellicle risk level.

[0081] In some embodiments, the control unit 314 can be configured to alert a field technician to replace the diaphragm 404 with a new qualified diaphragm in response to the radiant energy adjustment level (e.g., Eop percentage adjustment) being greater than a tolerable level (e.g., 5% or 5.5%). The control unit 314 can be configured to notify the field technician of the rupture risk level (e.g., low, medium, high).

[0082] Figure 11 is a plan view of a substrate 320 held by a substrate stage 306 according to some embodiments of the present disclosure. Figure 11 As shown, a plurality of shot regions S1 to S20 having predetermined sizes are defined on substrate 320. For example, shot regions S1 to S20 are arranged in a grid pattern on substrate 320. Each shot region S1 to S20 may include one or more die regions (not shown) where integrated circuits will be fabricated. The dashed line labeled P illustrates a process sequence for transferring the pattern on reticle 112 to shot regions S1 to S20.

[0083] Figure 10 Schematically illustrates a top view of a mask 402 according to some embodiments of the present disclosure. The mask 402 includes a component region 1002 and a boundary region 1004 formed at an edge of the component region 1002. The pattern of the mask 402 (e.g., Figure 3 、 Figure 4A The pattern 302P shown in FIG is formed in the feature area 1002. In addition, the boundary area 1004 is used to avoid overexposure from the edge of the mask 402 to the adjacent edges of two adjacent shot areas to be defined on the substrate 320 (see, for example, FIG. Figure 11The portion of the electromagnetic radiation ER_1 projected onto the boundary region 1004 will be absorbed accordingly. Figure 11 When irradiating shot area S8, the pattern in component area 1002 of mask 402 is transferred to shot area S8, and boundary area 1004 is used to at least prevent irradiation onto edges of adjacent shot areas S2, S7, S9, and S14.

[0084] As described above, the scanning velocity profile (including the steady-state scanning velocity and acceleration profile) of the reticle stage 304 affects the deformation of the pellicle membrane 404. Therefore, the deformation level of the pellicle membrane 404 is monitored during the exposure operation. If the deformation level of the pellicle membrane 404 provided by the inspection tool 203 exceeds a predetermined first threshold, the control unit 314 can determine that the pellicle membrane 404 is susceptible to rupture during the subsequent exposure operation. If the pellicle membrane 404 ruptures or is otherwise damaged during the exposure operation, the reticle 402 is no longer protected and may be scratched or otherwise damaged by the ruptured pellicle membrane 404 itself. Furthermore, the ruptured pellicle membrane 404 may break into pieces, and the debris from the broken pieces of the pellicle membrane 404 may contaminate the surrounding environment. This poses a risk of contaminating the exposure tool 202. Because of this risk, the methods and systems discussed herein address this risk through acceleration management plans and / or removal and replacement of the pellicle membrane.

[0085] On the other hand, if the deformation level of the pellicle film 404 provided by the inspection tool 203 remains below a predetermined second threshold (where the predetermined second threshold is less than the predetermined first threshold), the control unit 314 can determine that the pellicle film 404 has not deformed or has only slightly deformed from its original position, and that the optical, thermal, and mechanical properties of the pellicle film 404 are not adversely affected and require replacement. This is also discussed above with reference to designated risk levels. As discussed, a pellicle film 404 with a deformation level less than the predetermined second threshold can be determined to be at low risk of rupture. Furthermore, if the deformation level of the pellicle film 404 provided by the inspection tool 203 is between the predetermined first and second thresholds, the control unit 314 can determine that the pellicle film 404 is at a medium risk of rupture. Based on the risk level, an acceleration management plan can be implemented. In some embodiments, a deformation inspection of the pellicle film 404 can be performed prior to the exposure operation.

[0086] Figure 12A A cross-sectional view of an electrostatic chuck 1200 for holding a reticle, such as electrostatic chuck 304e of reticle stage 304 described above, is shown. Figure 12B shows a schematic diagram of an electrostatic chuck 1200 according to some embodiments, Figure 12C and Figure 12DA cross-sectional view of a static chuck 1200 and a reticle 402 is shown in accordance with some embodiments. Figure 12C and Figure 12D The electrostatic chuck 1200 can include a holder 1202 and a plurality of electrodes 1204a to 1204d. The holder 1202 can substantially seal the electrodes 1204a to 1204d to protect them from external contaminants (such as moisture and chemicals). In some embodiments, the holder 1202 is made of an insulating material.

[0087] The electrostatic chuck 1200 can be operated in a bipolar arrangement. For example, Figure 12C , a first voltage is applied to electrodes 1204a and 1204b, causing electrostatic charge (e.g., positive charge) to accumulate near electrodes 1204a, 1204b. Electrostatic charge of opposite polarity, e.g., negative charge, accumulates on the left side of reticle 402. Furthermore, a second voltage is applied to electrodes 1204c and 1204d, causing negative charge to accumulate near electrodes 1204c, 1204d. Electrostatic charge of opposite polarity, i.e., positive charge, accumulates on the right side of reticle 402. Thus, force F is generated by the electrostatic attraction between the accumulated charges of opposite polarity, wherein force F holds or secures reticle assembly 302 to reticle stage 304. Force F may be a Coulomb force.

[0088] In one embodiment, the holder 1202 may be an imperfect insulator. Therefore, over a period of time, unwanted electrostatic charge may accumulate within the holder 1202. If a large amount of unwanted electrostatic charge accumulates within the holder 1202, an attractive force may be exerted on the mask assembly 302 even after the voltage supplied to the electrodes 1204a to 1204d is turned off. Because of the attractive force generated, when the mask 402 is released from the mask carrier 304, the position of the mask 402 may change, or the mask 402 may be damaged by the force applied to the mask 402 during the release. By periodically reversing the polarity of the electrodes 1204a to 1204d, the unwanted electrostatic charge accumulated on the holder 1202 can be removed. This can be achieved by switching the polarity of the voltage applied to the electrodes 1204a to 1204d. As Figure 12D As shown, as the polarity of the voltage applied to electrodes 1204a to 1204d switches, negative charge accumulates near electrodes 1204a and 1204b, and positive charge accumulates near electrodes 1207c and 1204d. The positive and negative charges near electrodes 1204a to 1204d can neutralize or deplete unwanted electrostatic charge on holder 1202. In some embodiments, when the polarization is reversed, reticle 402 is released from the electrostatic chuck.

[0089] When the polarization of the electrostatic chuck 1200 is reversed (i.e., during the polarity switching period), an inspection of the pellicle 404, such as the sagging value, can be performed. After the inspection operation (e.g., a deformation test to determine the sagging value), the inspection tool 203 is configured to provide real-time inspection results of the pellicle 404 state to the control unit 314 to update the operating parameters of the exposure tool 202. Performing deformation measurements during the polarity switching period can save time.

[0090] Figures 13A-13L The schematic diagram illustrates scanning and stepping operations performed on two adjacent exposure regions according to some embodiments of the present disclosure. During an exposure operation, electromagnetic radiation ER illuminates a portion of reticle 402. Boundary region 1004 (and feature region 1002) within the illuminated portion patterns electromagnetic radiation ER_1, forming patterned electromagnetic radiation ER_2. Patterned electromagnetic radiation ER_2 is directed onto substrate 320 via projection optics module 310 and defines exposure region R on substrate 320.

[0091] In some embodiments, the projection optics module defines an exposure region R having an area that is reduced by a factor of two or more compared to the area of ​​the patterned electromagnetic radiation ER_1 at the reticle assembly 302. Alternatively, the projection optics module can be designed to define an exposure region R having an area that is greater than or equal to the area of ​​the patterned electromagnetic radiation ER_2 at the reticle 112. In some embodiments, the exposure region R has a rectangular shape, and the length of the exposure region R can be substantially equal to the width of each of the shot regions S1 to S20.

[0092] exist Figure 13A In FIG. 1 , the reticle 402 and the substrate 320 are moved synchronously in D1 with increasing acceleration. The scan is from point A to point B in the boundary region 1004 . Figure 14 The acceleration (ie, the scanning acceleration) is shown. It should be noted that the increasing speed or acceleration rate can be determined by a controller (such as controller 314) based on inputs from the film quality index and / or deformation / sagging test as described above. In other words, Figure 14 Provided by the Accelerated Management Program.

[0093] Figures 13B-13E In the embodiment, the pattern area 1002 of the mask 402 is scanned at a constant speed, as shown in FIG. Figure 14 Specifically, by synchronously moving the reticle 402 and substrate 320 relative to the projection optics module 310, the pattern of the reticle 402 can be transferred to the exposure area S1. In some embodiments, the reticle stage 304 and the substrate stage 306 move synchronously in the first direction D1. In one embodiment, the scanning speed can be determined by the controller 314.

[0094] exist Figure 13F-13G In FIG. 1 , the reticle 402 and the substrate 320 are moved synchronously along the direction D1 at a reduced speed. The scan is from point C to point D of the boundary region 1004 . Figure 14 A deceleration (ie, a reduction in scanning speed) is shown. Note that the reduction in rate may be determined by a controller (eg, controller 314) based on input from the film quality index and / or deformation / sag test as described above. In other words, Figure 14 Provided by the Accelerated Management Program.

[0095] After the first scan operation, the first step operation is performed. Figure 13H and Figure 13I During the first step operation, the reticle stage 304 remains stationary, while the substrate stage 306 moves the substrate 320 in the second direction D2 until the next shot region to be exposed (eg, shot region S2) is aligned with the exposure region R. The second direction D1 is, for example, the X direction.

[0096] Subsequently, a second scanning operation is performed to scan the irradiation area S2. Figures 13I-13K During the second scanning operation, the mask stage 304 moves the mask 402 and the substrate stage 306 moves the substrate 320 in the reverse first direction -D1, thereby scanning the irradiation area S2 from the right side of the irradiation area S2 to the left side of the irradiation area S2. Similarly, the exposure process is performed according to the scanning speed profile including acceleration management (i.e., increase / decrease in speed during the edge area of ​​the scan). When the second scanning operation of the irradiation area S2 is completed, a second stepping operation is performed between the irradiation areas S2 and S3. During the second stepping operation between the irradiation areas S2 and S3, the substrate stage 230 moves the substrate 320 in the second direction D2 to align the irradiation area S3 with the exposure area R, as shown in FIG. Figure 13L It should be noted that the velocity distribution corresponding to the second scanning operation is also given by Figure 14 reflected and may be provided by the controller 314 acceleration management plan.

[0097] As the exposure operation progresses, the pattern defined on the reticle 402 is sequentially transferred to the various shot regions S1 to S20 of the substrate 320 by repeating the scanning and stepping operations. In some embodiments, during the exposure operation, the odd-numbered shot regions (e.g., S1, S3, S5, etc.) are scanned from left to right, and the even-numbered shot regions (e.g., S2, S4, S6, etc.) are scanned from right to left. In alternative embodiments, all shot regions S1 to S20 can be scanned in the same direction (e.g., the first direction). In such an embodiment, during the stepping operation, the reticle stage 304 moves the reticle 402 in the opposite first direction -D1. Simultaneously, the substrate stage 306 moves the substrate 320 in the second direction D2 and in the opposite first direction -D1 to align the shot region to be exposed with the exposure region R. Compared to the exposure operation of scanning all the shot regions S1 to S20 in the same direction, the exposure operation of scanning the odd-numbered shot regions S1 to S20 in the reverse first direction -D1 while scanning the even-numbered shot regions S1 to S20 in the first direction D1 can reduce the stepping distance of the shot region R while completing the exposure task of all the shot regions S1 to S20. The scanning speed, acceleration, and deceleration during scanning the boundary region 1004 are provided by the controller 314 according to the acceleration management plan based on the risk of the pellicle 404.

[0098] Figure 15 A schematic diagram of a system 1500 is provided, which can be used with Figure 2 The systems shown are substantially similar and include designations for the surrounding environment. In one embodiment, a load port is provided in an atmosphere area (e.g., a clean room) for receiving a reticle assembly. In one embodiment, the load port receives a reticle cassette, such as Figure 4B A handler or robot is used to retrieve the reticle assembly and provide it to the load lock area. Within the load lock area, a transition to a vacuum atmosphere is provided. A second handler or robot is used to retrieve the reticle and pass it to various processes and features, including a barcode reader (2D BC reader), EUV inner box (EIP library) storage, overlay / replacement / removal features, as shown in the reference Figure 3 The mask carrier, as shown in measurement 203 and as shown in reference Figure 8-Figure 9 Example of the deflection / sagging measurement tool shown.

[0099] Figure 15The lithography system 1500 is shown to include an additional chamber for holding deformation measurements (e.g., a deformation / sag measurement tool). In one embodiment, the vacuum environment is not broken, e.g., maintained, between the tool, such as the deformation measurement tool, and the reticle stage. In other embodiments, the deformation / sag measurement tool is located outside the system (e.g., outside the vacuum chamber that includes the reticle stage for the EUV process). Since the inspection tool is arranged within the lithography system, the delivery time can be shortened. The inspection tool can also be configured to provide dynamic feedback measurement results to the acceleration controller (e.g., controller 314) to provide dynamic feedback to the acceleration controller. Figure 15 The reticle stage within the system provides dynamic feedback of the measurement results.

[0100] In one embodiment, Figure 15 The reticle assembly received at the load port of the system is arranged in an inner box (EIP) having a surrounding outer box (EOP) surrounding the EIP. The box can be the same as the one described above with reference to Figure 4B The cassettes discussed are essentially similar. In one embodiment, the outer cassette is opened in atmosphere to retrieve the inner cassette provided to the load lock. The inner cassette is then moved from the load lock chamber to the EIP library, where it is stored until use. A barcode reader (2D BC reader) can read the barcode on the reticle through a window of the inner cassette before or after storage. In one embodiment, the inner cassette is removed before the reticle is provided to the reticle stage.

[0101] Figure 16 is another flow chart illustrating a method 1600 according to aspects of one or more embodiments of the present disclosure. The method 1600 may be Figure 1Continuation of the method shown. Method 1600 includes block 1602 of receiving a reticle assembly, wherein the reticle assembly includes a reticle protected by a pellicle membrane. In one embodiment, the reticle assembly is disposed in a reticle cassette. Method 1600 also includes step 1604 of transporting the reticle assembly to an exposure tool and securing the reticle assembly to a reticle stage. At block 1606, the method includes obtaining parameters including a risk level of the pellicle membrane. At block 1608, determining a scan speed profile including an acceleration management plan for a scan speed of the reticle stage based at least in part on the risk level of the pellicle membrane. At block 1610, the method includes performing an exposure operation by driving the reticle stage according to the scan speed profile with acceleration management. In one embodiment, the acceleration management and scan speed are generated as described above by obtaining pellicle quality indices, including but not limited to pellicle stack configuration, power measurement (Eop) adjustment, wafer count, and receiving pellicle deformation or sagging measurements. In block 1606, these inputs are used to generate a risk level for the pellicle, which is then used to determine a scan velocity profile in block 1608, including providing a larger acceleration / deceleration rate for high-quality pellicles and a lower acceleration / deceleration rate for low-quality pellicles. In one embodiment, the inputs provided in block 1606 indicate that blocks 1608 and 1610 of method 1600 are omitted and the pellicle is replaced.

[0102] Method 1600 is described to illustrate the concepts of the present disclosure and is not intended to limit the present disclosure. Additional operations may be provided before, during, and after the above method, and for other embodiments of method 1600, some operations described in method 1600 may be replaced, eliminated, or moved.

[0103] Figure 17 Method 1700 is shown and will be described below using the above-described lithographic apparatus 200 as an example, along with aspects of methods 1600 and 100. Method 1700 begins at block 1702, where a reticle assembly, such as reticle assembly 302, is received. Reticle assembly 302 includes reticle 402 having a pattern 302P to be transferred to a material layer (e.g., photoresist 322) of a substrate (e.g., wafer 320). A pellicle membrane 404 of the reticle assembly protects the reticle pattern 302P from contamination.

[0104] Method 1700 continues at block 1704, where the reticle assembly 302 is transported to a tool that can be used with Figure 2 and / or Figure 15 Substantially similar, an exposure tool having a reticle stage is provided. In one embodiment, when the reticle assembly is contained in a cassette structure as described above, block 1704 is performed.

[0105] Method 1700 then proceeds to blocks 1706 and 1708, where operating parameters and a pellicle quality index are collected for the exposure tool. The operating parameters may include acquired state indices, including one or more of energy on power (EOP) state, wafer motion (WM) state, pellicle type (e.g., pellicle film solution details), the original state of the pellicle film (e.g., deformation), a baseline scan speed profile, and / or other suitable parameters. The baseline scan speed profile may include a scan speed (e.g., a uniform speed for scanning component area 1002) and an acceleration profile (e.g., rate and pulse shape). That is, in some embodiments, the scan speed profile includes multiple segments. The segments of the scan speed profile may correspond to component area 1002 and boundary area 1004 of reticle 402. In some embodiments, the scan speed profile includes three segments: an initial segment (e.g., acceleration), a scan segment, and a final segment (e.g., deceleration). In some embodiments, the initial segment, the scan segment, and the final segment are identified based on the boundaries of component area 1002 and boundary area 1004. In one embodiment, the scan speed is a first speed. In another embodiment, the scanning speed is about 300 mm / s. In one embodiment, the acceleration of the scanning speed is given by m / s 2 In one embodiment, the baseline is about 75 m / s 2 .

[0106] Method 1700 then proceeds to block 1708, where a risk level is determined. The parameters of block 1706 may be used to determine the risk level of the pellicle. According to some embodiments, the risk level of the pellicle diaphragm 404 is determined based on a level of deformation of the pellicle diaphragm 404. The degree of deformation of the pellicle diaphragm 404 may be provided by the inspection tool 203. Alternatively, if the inspection tool 203 is not directly coupled to the lithographic apparatus 200, the deformation level of the pellicle diaphragm 404 may be obtained from the inspection tool 203 via the database 316. The risk level of the pellicle diaphragm 404 is determined based on the parameters of block 1706, which may include, in addition to the deformation level of the pellicle diaphragm 404, at least one of the adjustment level of the radiation energy of the radiation source 324, the movement speed of the reticle stage 304, and the composition of the pellicle diaphragm 404. Determining the risk level is discussed above.

[0107] Method 1700 then proceeds to block 1710, where a determination is made as to whether the pellicle is at high risk of rupture. In some embodiments, this determination includes determining a level of deformation of the pellicle membrane 404. This determination may also include determining an adjusted level of radiant energy. In some embodiments, in response to determining that the pellicle membrane 404 is at high risk of rupture, the current pellicle membrane 404 is replaced with a new or qualified pellicle membrane 404 (step 1712), and method 1700 then proceeds back to block 1706.

[0108] The method 1700 then proceeds to block 1714 where a medium risk is determined. If a medium risk is determined, then in block 1716 a new scan profile is generated to reduce the pressure on the reticle 402. Figure 14 As described above, the scanning speed distribution includes an acceleration section, a constant speed section, and a deceleration section. The acceleration section is located at the starting point of the scanning path identified by boundary points A and D. The constant speed section is after the acceleration (speeding up) section, and the deceleration (slowing down) section after the constant speed section is located at the end point of the scanning path. In the acceleration section, the scanning speed increases from 0 to the second speed S2 at an acceleration value. In one embodiment, the acceleration value can remain substantially constant during the acceleration section. In block 1716, the acceleration value can be reduced to reduce the pressure on the mask 402. In the constant speed section, the scanning speed is substantially fixed at the second speed S2. In the deceleration section, the scanning speed is reduced from the second speed S2 to 0 at a deceleration value. During the deceleration section, the deceleration value can remain substantially constant. In block 1716, the deceleration value can be reduced to reduce the pressure on the mask 402. Method 1700 moves reticle stage 304 according to a non-uniform scan velocity profile, which can mitigate undesirable airflow around pellicle membrane 404 and extend the useful life of pellicle membrane 404. In one embodiment, the acceleration / deceleration value can be reduced from the baseline (e.g., from 75 m / s to 2 Reduced to 50m / s 2 In other embodiments, the baseline scan speed profile can include a constant speed, including a constant speed during scanning of the boundary region 1004 of the reticle 402 .

[0109] Method 1700 then proceeds to block 1718, where a low risk is determined. In response to determining that pellicle membrane 404 is at a low risk of rupture, a baseline scan profile can be maintained in block 1720. The scan profile of block 1716 or 1720 is then used in block 1722 to perform a scan exposure on a substrate (e.g., wafer) 320 provided to exposure tool 202. Method 1700 can be repeated throughout the manufacturing process and life of the reticle assembly and pellicle membrane.

[0110] According to some embodiments of the present disclosure, a method for operating a lithographic apparatus is provided. The method includes the following steps: receiving a reticle assembly including a reticle and a pellicle membrane, transporting the reticle assembly to an exposure tool, and securing the reticle assembly to a reticle stage of the exposure tool. The method also includes determining a scanning speed profile based on a risk level associated with the quality of the pellicle membrane. The method also includes performing an exposure operation by driving the reticle stage according to the scanning speed profile.

[0111] In one embodiment, the method further comprises: measuring a deformation of the pellicle membrane to determine a sagging value; and using the sagging value to determine a scanning speed distribution. In one embodiment, determining the scanning speed distribution comprises determining: an initial segment at the start of a scanning path, driving the reticle stage to move at a first acceleration in the initial segment; a scanning segment after the initial segment, driving the reticle stage at a substantially constant speed in the scanning segment; and a final segment at the end of the scanning path after the scanning segment, driving the reticle stage to move at a first negative acceleration in the final segment. In another embodiment, determining the scanning speed distribution comprises reducing the baseline acceleration to the first acceleration due to the risk level. In some cases, the reticle includes a component area and a boundary area surrounding the component area, and the scanning path begins at a lower boundary of the boundary area and ends at an upper boundary of the edge area.

[0112] In one embodiment, the pellicle membrane is determined to have a risk level based on at least one of its composition, deformation level, radiation energy adjustment level, number of substrates processed, and movement speed of a substrate stage supporting the substrates to be exposed. In another embodiment, the method includes issuing an alarm signal when the radiation energy adjustment level exceeds a tolerable level. In yet another further embodiment, driving the reticle stage according to the scanning speed profile further includes replacing the pellicle membrane with a qualified pellicle membrane in response to the pellicle membrane being at high risk of rupture.

[0113] In one embodiment, the method further includes: removing the reticle assembly from the reticle stage and transporting the reticle assembly to an inspection tool; irradiating the inspection beam onto the pellicle membrane and detecting scattered light beams after the irradiation; and determining a deformation level of the pellicle membrane based on the detected scattered light beams, wherein the deformation level is used to determine the risk level. In another embodiment, irradiating the inspection beam is performed during a polarity switching period of the reticle stage.

[0114] According to some embodiments of the present disclosure, a method for operating a lithographic apparatus includes receiving a reticle assembly. The reticle assembly includes a reticle and a pellicle sheet. The reticle assembly is secured to a reticle stage of an exposure tool. The method further includes obtaining a pellicle quality index and determining a first scanning speed profile for the reticle stage based on the pellicle quality index. An exposure operation is performed on a substrate according to the first scanning speed profile.

[0115] In one embodiment, the method includes: obtaining a pellicle quality index including an energy on power (EOP) state, a wafer movement (WM) state, a pellicle type or a deformation state of a pellicle film of a mask assembly. In some embodiments, the method further includes replacing the pellicle film with a qualified pellicle film in response to the pellicle film being at a high risk of rupture. In one embodiment, obtaining the pellicle quality index includes receiving a sag value from a measuring device. In some embodiments, obtaining the pellicle quality index includes measuring the deformation of the film of the mask assembly before fixing the mask assembly on the mask carrier. In another embodiment, a vacuum atmosphere is maintained between measuring the deformation and fixing the mask assembly on the mask carrier. In one embodiment, the mask assembly is fixed to the mask carrier via an electrostatic chuck, and the measurement of the deformation of the pellicle film includes obtaining the sag value of the pellicle film during a polarity switching period of the electrostatic chuck.

[0116] According to some embodiments of the present disclosure, a lithography apparatus includes an exposure tool, the exposure tool comprising: a reticle stage operable to hold a reticle assembly, wherein the reticle assembly includes a reticle protected by a pellicle membrane, and the reticle stage operable to move the reticle assembly in a first direction; a substrate stage operable to hold a substrate, wherein the substrate stage is operable to move the substrate relative to the reticle assembly; and a control unit electrically coupled to the reticle stage. The lithography apparatus also includes an inspection tool configured to obtain a deformation level of a pellicle, wherein the control unit is configured to determine a scanning speed profile of the reticle stage based at least on the deformation level of the pellicle membrane.

[0117] According to some embodiments of the present disclosure, the apparatus further includes a radiation source configured to generate electromagnetic radiation having radiation energy. The electromagnetic radiation is directed toward a reticle, and the reticle reflects and patterns the electromagnetic radiation to form patterned electromagnetic radiation. The apparatus further includes a detector configured to obtain exposure energy of the patterned electromagnetic radiation and generate a detection result. In some embodiments, the control unit is further configured to tune the radiation energy based on the detection result and determine the adjusted level of the radiation energy.

[0118] The features of several embodiments are summarized above so that those skilled in the art can better understand the various aspects of the present disclosure. Those skilled in the art will appreciate that they can easily use the present disclosure as a basis for designing or modifying other processes and structures for achieving the same purpose and / or achieving the same advantages of the embodiments introduced herein. Those skilled in the art will also appreciate that such equivalent structures do not depart from the spirit and scope of the present disclosure, and that they can make various changes, substitutions, and modifications in the present disclosure without departing from the spirit and scope of the present disclosure.

Claims

1. A method of operating a lithographic apparatus, comprising: receiving a reticle assembly including a reticle and a pellicle sheet; transporting the mask assembly to an exposure tool, and fixing the mask assembly on a mask carrier of the exposure tool; determining a scanning speed profile based on a risk level associated with the quality of the pellicle membrane; as well as An exposure operation is performed by driving the reticle stage according to the scanning speed profile.

2. The method according to claim 1, further comprising: measuring the deformation of the pellicle membrane to determine a sag value; as well as The sag value is used to determine the scanning speed profile.

3. The method according to claim 1, wherein Determining the scanning velocity distribution includes determining: an initial section at a starting point of a scanning path, wherein the reticle stage is driven to move at a first acceleration in the initial section; a scanning section following the initial section, wherein the reticle stage is driven at a substantially constant speed in the scanning section; and A final section at an end of the scanning path following the scanning section, wherein the reticle stage is driven to move at a first negative acceleration in the final section.

4. The method according to claim 3, wherein: Determining the scanning velocity profile includes reducing a baseline acceleration to the first acceleration due to the risk level.

5. The method according to claim 3, wherein: The reticle includes a component area and a boundary area surrounding the component area, and the scanning path starts at a lower boundary of the boundary area and ends at an upper boundary of the edge area.

6. The method according to claim 1, wherein The pellicle is determined to have the risk level based on at least one of a composition of the pellicle, a deformation level of the pellicle, an adjustment level of radiation energy, a number of processed substrates, and a movement speed of a substrate stage supporting a substrate to be exposed.

7. The method according to claim 1, further comprising: removing the reticle assembly from the reticle stage and transporting the reticle assembly to an inspection tool; irradiating an inspection light beam onto the pellicle membrane and detecting a scattered light beam after the irradiation; and A deformation level of the pellicle membrane is determined based on the detected scattered light beam, wherein the risk level is determined using the deformation level.

8. A method of operating a lithographic apparatus, comprising: receiving a mask assembly, wherein the mask assembly includes a mask and a pellicle; Fixing the mask assembly on the mask carrier of the exposure tool; Obtaining the surface film quality index; determining a first scanning speed distribution of the reticle stage based on the pellicle quality index; and An exposure operation is performed on the substrate according to the first scanning speed profile.

9. The method according to claim 8, wherein Obtaining the pellicle quality index includes the power energy state, wafer movement state, pellicle type or deformation state of the pellicle film of the mask assembly.

10. A lithographic apparatus comprising: Exposure tools, including: a reticle stage operable to secure a reticle assembly, wherein the reticle assembly includes a reticle protected by a pellicle membrane, and the reticle stage operable to move the reticle assembly in a first direction; a substrate stage operable to hold a substrate, wherein the substrate stage is operable to move the substrate relative to the reticle assembly; and a control unit electrically coupled to the reticle stage; and an inspection tool configured to obtain a deformation level of the diaphragm sheet, The control unit is configured to determine a scanning speed distribution of the reticle stage based at least on the deformation level of the pellicle membrane.

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