Method of extreme ultra-violet lithography, method of performing lithography, and extreme ultra-violet lithography system

Abstract

The present disclosure provides a method for a lithographic system that includes one or more thermal sensors that provide feedback to a thermal management controller. The thermal management controller provides instructions to thermal conditioning assemblies, such as heat exchangers and gas nozzles, to provide cooling of a reticle used in a lithographic system. Embodiments of the present disclosure also relate to a method of extreme ultraviolet lithography, a method of performing lithography, and an extreme ultraviolet lithography system.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to a method of extreme ultraviolet lithography, a method of performing lithography, and an extreme ultraviolet lithography system. Background Art

[0002] The semiconductor integrated circuit (IC) industry has experienced exponential growth. Technological advances in IC materials and design have produced multiple generations of ICs, each with smaller and more complex circuits than the previous generation. 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 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. This scaling down also increases the complexity of processing and manufacturing ICs.

[0003] To achieve these advances, similar developments in IC processing and manufacturing are needed. For example, there is an increased demand to perform higher resolution lithography processes. One lithography technique is extreme ultraviolet (EUV) lithography. EUV lithography employs a scanner that uses light in the extreme ultraviolet region having a wavelength of about 1-100 nm. EUV scanners use reflective rather than refractive optical elements, i.e., mirrors rather than lenses. However, while existing lithography techniques are generally adequate for their intended purposes, they are not completely satisfactory in every respect. Summary of the invention

[0004] Embodiments of the present disclosure provide a method for extreme ultraviolet (EUV) lithography, the method comprising: collecting thermal data associated with an intermediate mask during a lithography process; receiving design data associated with a pattern on the intermediate mask; and using the thermal data and the design data to determine a thermal management action, wherein the thermal management action comprises providing instructions to a thermal regulation component to cool the intermediate mask.

[0005] Another embodiment of the present disclosure provides a method for performing lithography, wherein the method includes: providing a mask to a mask holder of a lithography tool; providing a target substrate to a wafer stage of the lithography tool; transmitting a radiation beam from a source of the lithography tool, wherein the transmitted radiation beam reflects off the mask; providing the reflected radiation beam to the target substrate; and performing thermal control management during the transmission of the radiation beam, wherein the thermal control management includes: receiving a temperature associated with the mask holder, receiving a temperature associated with the mask, modifying an output of a thermal regulation component based on the received temperature, wherein modifying the output includes determining an airflow.

[0006] Another embodiment of the present disclosure provides an extreme ultraviolet (EUV) lithography system, comprising: an intermediate mask holder; a temperature sensor; a first thermal regulation component located in the intermediate mask holder, wherein the first thermal regulation component is used to reduce the temperature of the intermediate mask in the intermediate mask holder; a second thermal regulation component spaced a certain distance from the intermediate mask holder, wherein the second thermal regulation component is used to provide airflow adjacent to the intermediate mask in the intermediate mask holder; and a control module coupled to the temperature sensor, the first thermal regulation component and the second thermal regulation component. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Aspects of the present disclosure are best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that, in accordance with standard practice in the industry, the various components are not drawn to scale. In fact, the dimensions of the various components may be arbitrarily increased or reduced for clarity of discussion.

[0008] Figure 1 is a block diagram of an embodiment of a lithography system having a thermal control module constructed in accordance with some embodiments.

[0009] Figure 2A is a schematic diagram of an EUV mask manufactured according to some embodiments; Figure 2B and Figure 2C is a schematic diagram of the interaction of an EUV mask with environmental conditions of a lithography process according to some embodiments.

[0010] Figure 3 is a diagrammatic representation of molecular structures and interactions occurring in a lithographic environment according to some theories of the present disclosure.

[0011] Figure 4 is a block diagram of an example of a lithography system having a thermal control module according to some implementations of the present disclosure.

[0012] Figure 5 , Figure 6 , Fig. 7A , Fig. 8A and Fig. 9 are schematic diagrams of various embodiments implementing features of thermal control management according to aspects of the present disclosure.

[0013] Figure 7B and Figure 7C is a diagrammatic illustration of exemplary design data that may be used in aspects of the present disclosure.

[0014] Figure 8B is a graphical illustration of an exemplary thermal profile implemented in aspects of the present disclosure.

[0015] Fig.10is a schematic diagram of an embodiment of an EUV lithography system according to some aspects of the present disclosure.

[0016] Fig.11 is a flow chart of an embodiment of a method of developing a thermal control plan according to some aspects of the present disclosure.

[0017] Fig.12 is a flow chart of an embodiment of performing a photolithography process including thermal management according to aspects of the present disclosure. DETAILED DESCRIPTION

[0018] The following disclosure provides many different embodiments or examples for realizing different features. Reference numbers and / or letters may be repeated in the various examples described herein. This repetition is for the purpose of simplicity and clarity, and does not itself indicate the relationship between the various disclosed embodiments and / or configurations. In addition, specific examples of components and arrangements are described below to simplify the present disclosure. Of course, these are only 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 formed to be in direct contact, 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, in the present disclosure, the formation of a component located on another component, connected to another component and / or coupled to another component may include an embodiment in which the component is formed to be in direct contact, and may also include an embodiment in which an additional component may be formed between the components, so that the components may not be in direct contact.

[0019] 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 in itself indicate the relationship between the various embodiments and / or configurations discussed. In addition, in the present disclosure, the formation of a component located on, connected to, and / or coupled to another component may include an embodiment in which the component is formed to be in direct contact, and may also include an embodiment in which an additional component may be formed between the components so that the components may not be in direct contact. In addition, in order to facilitate the present disclosure to describe the relationship between one component and another component, spatial relative terms are used, for example, "lower", "upper", "horizontal", "vertical", "above...", "above...", "below...", "below...", "upward", "downward", "top", "bottom", etc. and their derivatives (e.g., "horizontally", "downward", "upward", etc.). Spatial relative terms are intended to cover different orientations of devices including components. Further, when "about", "approximately", etc. are used to describe a numerical value or a numerical range, the term is intended to include numerical values ​​within a reasonable range, including the described numerical values, such as within + / -10% of the described numerical values ​​or other values ​​understood by those skilled in the art. For example, the term "about 5 nm" includes a size range from 4.5 nm to 5.5 nm.

[0020] The present disclosure includes embodiments of an extreme ultraviolet (EUV) lithography apparatus integrated with an EUV control system, the EUV control system being designed to monitor, analyze and / or control the EUV lithography apparatus and the method of enhancing performance through thermal management performed by the EUV lithography apparatus and the method. The present disclosure also includes a method that uses a control system to monitor thermal conditions and actively adjust and control aspects of the EUV lithography apparatus so that when the EUV lithography apparatus is used in integrated circuit (IC) manufacturing, the lithography process is improved in some embodiments. In particular, the method and the EUV control system are associated with an EUV lithography apparatus for patterning IC structures in advanced technology nodes. The IC structure may include a field effect transistor (FET), a fin FET (FinFET), or a multi-gate device, such as a full-ring gate (GAA) device according to various embodiments.

[0021] However, while the present disclosure provides exemplary systems and methods for implementing EUV lithography, it should be understood that lithography utilizing other wavelengths and other processing steps may benefit from aspects of the present disclosure. Accordingly, the present disclosure includes thermal management of other systems, including other lithography systems.

[0022] Figure 11 is a block diagram of a lithography system 10 constructed according to some embodiments. The lithography system 10 may also be generally referred to as a scanner, which is used to perform a lithography exposure process using a corresponding radiation source and an exposure mode. In an embodiment, the lithography system 10 is an extreme ultraviolet (EUV) lithography system, which is designed to expose a target photoresist layer by EUV light, wherein the photoresist layer is a suitable material sensitive to EUV light.

[0023] In an embodiment, the lithography system 10 includes an EUV source 14 (or simply source 14) for generating EUV radiation 18. In some embodiments, the radiation source 14 uses a laser produced plasma (LPP) mechanism to generate plasma and further generate EUV light from the plasma. For example, the radiation source 14 may include one or more lasers (such as a pulsed carbon dioxide laser) to generate a laser beam. In some embodiments, the laser source includes two laser devices, one for generating a pre-pulse impact on a target material or droplet, and the other for generating a main pulse impact on the target material. The laser may also include one or more laser amplifiers to further amplify the power of the laser beam. In an embodiment, the laser beam is directed through a transparent window integrated with a collector (also referred to as an EUV collector). The collector is designed with appropriate coating materials and shapes to act as a reflector for EUV collection, reflection and focusing. In some embodiments, the coating material of the collector is similar to a reflective multilayer such as an EUV mask discussed below.

[0024] As introduced above, in an embodiment, the laser beam is directed to heat the target material or droplets, thereby generating a high temperature plasma, which further produces EUV radiation (or EUV light) 18. In an embodiment, the target material is tin (Sn). The collector reflects and focuses the EUV radiation 18 for lithography exposure processes, including those discussed with reference to the system 10 below.

[0025] Before reaching the target substrate, the generated EUV radiation 18 is processed by a series of optical elements referred to as an optical system. As used herein, the term "optical element" should be broadly interpreted to include, but not necessarily limited to, one or more components that reflect and / or transmit and / or operate on incident light, and includes, but is not limited to, one or more lenses, windows, filters, wedges, prisms, prism gratings, grading, transmission fibers, etalons, diffusers, homogenizers, detectors and other instrument components, apertures, axicons, and reflectors, including multilayer mirrors, near normal incidence mirrors, grazing incidence mirrors, specular reflectors, diffuse reflectors, and combinations thereof. In addition, unless otherwise specified, the term "optical element" as used herein is not meant to be limited to components that operate only in one or more specific wavelength ranges (such as in EUV). However, for ease of explanation, embodiments of the system 10 for EUV wavelengths are discussed herein. As part of the optical system, the system 10 includes an illuminator 20. In various embodiments for EUV lithography, the illuminator 20 includes a reflective optical element, such as a single mirror or a mirror system having a plurality of mirrors, to direct the radiation 18 from the radiation source 14 toward the mask 12. The illuminator 20 may include a field facet (FF) mirror and a pupil facet (PF) mirror. The facet mirror is an optical element that can be used to generate a homogenization of the radiation 18 generated by the EUV source 14.

[0026] After passing through illuminator 20, radiation 18 is provided such that radiation 18 is incident on the exposed surface of mask 12. In this disclosure, the terms mask, photomask, and reticle are used to refer to patterned structure 12 to which incident radiation 18 is provided.

[0027] The lithography system 10 includes a mask holder 16 (also referred to as a stage or chuck) configured to hold, secure, and position a mask 12. In some embodiments, the mask stage 16 includes an electrostatic chuck (e-chuck) to secure the mask 12. Thus, an electronic fixture can be used to secure the mask 12 to the mask stage 16. In some embodiments, the mask stage 16 includes one or more fixtures for securing the mask 12. In an embodiment, the mask stage 16 includes one or more thermal conditioning components 16A to provide cooling or temperature reduction to the mask stage 16, the mask 12 held by the mask stage 16, and / or the surrounding environment. The thermal conditioning component 16A may be operably coupled to a thermal control system 30 discussed below. The thermal conditioning component 16A may include a heat exchanger, a coolant (gas or liquid), a solid cooling module, a heat pipe module, and / or other thermal management components. In an embodiment, the thermal conditioning component 16A includes a coolant. In an embodiment, the thermal conditioning component 16A operates without a coolant. Thermal conditioning assembly 16A may provide for reducing the temperature of mask 12 and / or its surrounding environment (retardant microenvironment). This reduction in temperature may maintain mask 12 and layers formed thereon at a temperature that reduces outgassing, such as reducing bond breakage between atoms of layers of mask 12 due to a reduction in available thermal energy. In some embodiments, mask holder 16 includes a temperature sensor (e.g., a thermocouple) for providing a temperature that is helpful in understanding the function of the thermal conditioning assembly. In certain embodiments, system 10 may also include other thermal conditioning assemblies, such as gas jets or nozzles that provide a gas in the retardant environment (discussed below).

[0028] In an embodiment, the mask 12 is a reflective mask suitable for EUV lithography patterning. The mask 12 of the system 10 is briefly discussed. The mask may include a substrate having a reflector (or reflective layer), such as a multilayer mirror (MLM) disposed on a substrate. An absorption layer may be disposed on the MLM. Typically, areas in the mask where the absorption layer is present absorb incident radiation, while areas in the mask where the absorption layer is not present reflect incident radiation toward a target. The mask 12 may include a substrate having a suitable material, such as a low thermal expansion material (LTEM) or fused quartz, on which the MLM and the absorption layer are formed. In some embodiments, an EUV film is positioned above the mask 12. The EUV film provides a film that protects the EUV mask from contaminant particles or other substances that may damage the mask. The EUV film is typically coupled to the EUV mask by one or more frames. In some embodiments, there is no EUV film.

[0029] The lithography system 10 also includes a projection optical element (sometimes referred to as a projection optical element box (POB)) 22 as part of the optical system. The projection optical element 22 is used to image the pattern of the mask 12 onto a target substrate 24, such as a semiconductor wafer, which is fixed on a substrate stage 26 of the lithography system 10. In the case of EUV lithography embodiments, the projection optical element 22 may include a reflective optical component, including a monolithic mirror and / or a mirror array. The projection optical element may include a pupil phase modulator. EUV light (carrying an image of the pattern defined on the mask 12) is directed from the mask 12 and collected by the projection optical element 22. The illuminator 20 and the projection optical element 22 are sometimes collectively referred to as an optical module of the lithography system 10.

[0030] After projection optics 22, the patterned radiation beam is then delivered to a target substrate 24. Like the optical systems and masks discussed above, the target substrate may be provided in an exposure chamber that is also maintained in a vacuum environment to reduce undesired absorption of radiation 18. The exposure chamber may include a wafer stage 26 to hold a semiconductor substrate (such as a wafer). In various embodiments, target substrate 24 includes a semiconductor wafer, such as a silicon wafer, a germanium wafer, a silicon germanium wafer, a III-V wafer, or other types of wafers as described above or known in the art. Target substrate 24 may be coated with a photoresist layer (e.g., an EUV photoresist layer) that is sensitive to the radiation from source 14. The radiation incident on substrate 24 causes an image of the pattern defined on mask 12 or a portion thereof to be directed onto the semiconductor substrate, or specifically onto a photoresist layer (also referred to as a photoresist layer) coated on the surface of the semiconductor substrate. Portions of the light-sensitive photoresist layer exposed to the radiation undergo a chemical transformation that makes them more or less sensitive to the development process.

[0031] In some embodiments, mask 12 and substrate 24 can be provided in the same environment (e.g., each in a continuous vacuum environment). That is, because gas molecules absorb EUV light, the EUV chamber or portion thereof can be subjected to a vacuum environment to avoid EUV intensity loss. There may be abutment between the photoresist and the intermediate mask, which may increase the possibility of contamination between substrate 24 and mask 12. Aspects of the present disclosure can be used to reduce contamination as discussed herein.

[0032] The lithography system 10 also includes a thermal control system or module 30 coupled to or integrated with the lithography system 10. The thermal control module 30 is designed to have mechanisms for monitoring various parameters (including temperature) of the EUV lithography device, collecting information from various databases, analyzing the collected data and / or parameters, performing simulations, and / or actively adjusting or controlling variables of the lithography system 10. In some embodiments, the thermal control module 30 provides instructions to perform thermal control management of the lithography process provided in the lithography system 10. In some embodiments, the thermal control module 30 provides instructions to adjust or control thermal regulation components including 16A. In some embodiments, the lithography system 10 includes a gas supply module, which is designed to provide gas to the system. In an embodiment, the gas supply module can be operably coupled to the thermal control module 30. The gas supply module can be instructed to provide gas suitable for thermal management of the lithography system 10.

[0033] The thermal control module 30 includes various units, sensors, modules and components that are integrated and configured to perform various functions, including collecting data of the thermal control module 30. In an embodiment, the thermal sensors that provide information to the thermal control module 30 include thermocouples, IR cameras / sensors, UV sensors, light sensors and / or other suitable components. The various parts of the thermal control module 30 can be distributed in various locations, such as partially embedded and configured in the lithography system 10; or partially stand together and couple with the lithography system 10 through Internet communication (such as Internet cable connection, WiFi connection, Bluetooth connection, other suitable connection or combination thereof). The thermal control module 30 can be integrated with other control systems of the lithography system 10. The thermal control module 30 also includes suitable computer hardware, including a processor and memory. The memory includes a computer program executed by the processor, including the analysis of the thermal control module discussed herein.

[0034] Various components including those described above are integrated together and used to perform EUV lithography exposure processes using the lithography system 10. The thermal control module 30 provides for performing lithography processes with thermal management as discussed in further detail below. The lithography system 10 may also include other modules or be integrated (or coupled) with other modules.

[0035] In some embodiments, the lithography system 10 is used to manufacture an integrated circuit (IC) or a portion thereof. In some embodiments, the lithography system 10 is used to form static random access memory (SRAM) and / or other logic circuits, passive components (such as resistors, capacitors, and inductors), and active components (such as p-type FETs (PFETs), n-type FETs (NFETs), fin FETs (FinFETs), metal oxide semiconductor field effect transistors (MOSFETs), complementary metal oxide semiconductor (CMOS) transistors, bipolar transistors, high voltage transistors, high frequency transistors, full gate all around (GAA) devices, and / or other devices). The present disclosure is not limited to any particular semiconductor device.

[0036] As discussed above, aspects of the present disclosure are illustrated by the performance of EUV systems and / or EUV lithography. However, aspects of the present disclosure may also be provided in other systems and / or used to perform lithography processes at other wavelengths. Thus, in some embodiments, source 14 generates radiation 18 having a wavelength such as X-rays, DUV, I-line, G-line, and / or other available wavelengths. Thus, the components of the optical path include components suitable for the selected wavelength, including mirrors, lenses, liquid environments, thin film mirrors, beam splitters, gratings, phase shifter components, etc. Similarly, mask 12 is configured to appropriately pattern the provided radiation, for example, providing a phase shift mask, a transmission mask, and / or other suitable masks.

[0037] Reference now Figure 2A , an exemplary mask or intermediate mask 12 is shown in further detail. Mask 12 may be an EUV mask. In the embodiments described herein, lithography system 10 is an EUV lithography system, and mask 12 is a reflective mask for performing EUV lithography. Thus, generally, areas of mask 12 where absorber layer 206 is present absorb incident radiation, such as radiation 18, while areas of the mask where absorber layer is not present reflect incident radiation toward a target, thereby providing patterned radiation 18.

[0038] The mask 12 includes a substrate 200 having a suitable material, such as a low thermal expansion material (LTEM) or fused silica. Exemplary low thermal expansion materials include quartz and LTEM glass, silicon, silicon carbide, silicon oxide, titanium oxide, Black (trademark of Applied Materials, Inc.), TiO2-doped SiO2, and / or other low thermal expansion substances known in the art. Above substrate 200 are a plurality of reflective layers forming a multilayer (ML) 202. ML 202 includes a plurality of film pairs, such as molybdenum-silicon (Mo / Si) film pairs (e.g., in each film pair, a molybdenum layer is located above or below a silicon layer). Alternatively, the ML may include a molybdenum-beryllium (Mo / Be) film pair, or other suitable material that may be configured to be highly reflective of EUV light. The number of layers, the thickness of the layers, and the materials of the layers are selected based on the exposure radiation and its characteristics (such as wavelength and / or angle of incidence) to provide a desired reflectivity. In an embodiment, a plurality of Mo / Si pairs (e.g., 40 pairs) are formed to provide reflective layer 202. ML 202 forms a multilayer reflector for reflecting incident radiation.

[0039] The mask 12 may also include a capping layer 204. In some embodiments, the capping layer 204 is disposed on the ML 202 to protect the ML 202 from oxidation. In an embodiment, the capping layer 204 is ruthenium (Ru). In an embodiment, the thickness of the capping layer 204 is between about 2 nanometers and 10 nanometers (nm), such as about 3.5 nanometers (nm). An absorption layer 206 may be formed on the capping layer 204. The absorption layer 206 is patterned according to the desired patterning of the radiation beam associated with the component to be manufactured on the target substrate. The absorption layer 206 includes a first absorption layer 206A and a second absorption layer (serving as an anti-reflective coating (ARC)) 206B thereon. In some embodiments, the absorption layer 206 includes boron. Example components include, but are not limited to, TaBN (e.g., 206A) and TaBO (e.g., 206B). In some embodiments, the absorption layer also includes other elements (e.g., chromium). In an embodiment, the thickness of the absorption layer 206A is between about 30nm and 120nm, such as 68nm. In an embodiment, the thickness of the ARC layer is between 1 nm and 10 nm, such as about 2 nm.

[0040] In some embodiments, a conductive backside coating 208 is provided on the opposite side of the substrate 200. The conductive backside coating 208 can be used to secure the mask 12 to an electrostatic chuck, such as described above with reference to FIG. Figure 1 The stage 16 of the photolithography system 10 is depicted. Therefore, in some embodiments, the coating 208 is referred to as a chuck layer. Exemplary electrostatic chuck layer materials include chromium nitride (CrN), chromium oxynitride (CrON), chromium (Cr), tantalum boron nitride (TaBN), tantalum silicide (TaSi), and / or other suitable materials.

[0041] exist Figure 2B, mask 12 is shown in an environment in which a photolithography process is performed using mask 12. EUV radiation beam 18 is incident on mask 12 including absorber layer 206. In an embodiment, EUV radiation beam 18 has a wavelength centered at 13.5 nm. Mask 12 can be in a vacuum environment. In further embodiments, hydrogen is available in the environment, such as Figure 2B 206. In some cases, the incident radiation 18 can provide sufficient energy to release boron atoms from the absorption layer 206. The released boron atoms can bond with available hydrogen. In some cases, the bonding forms BH3. The formed BH3 can be provided in gaseous form. Other compounds can also be formed, including but not limited to diborane. Figure 2C The formation of BH 3 is shown, referred to as outgassing. Thus, outgassed BH 3 may be present in the photolithography system 10 , such as in a vacuum chamber including the mask 12 .

[0042] As reference Figure 1 As shown, the mask 12 can be provided in a continuous environment such that the environment extends from the mask 12 through the projection optical element 22 to the substrate 24. In such an embodiment, outgassing from the target substrate 24 can be mixed with outgassing from the mask 12. Exemplary outgassing from the photoresist includes, but is not limited to, carbon-based components. In some embodiments, the photoresist layer on the target substrate 24 produces outgassing of carbon-based components such as methylamine.

[0043] Outgassing materials from mask 12 and outgassing materials from the photoresist of substrate 24 may mix to form undesirable compounds that provide contaminants to system 10 and its components. Figure 3 In the reaction shown, outgassing components from mask 12 (e.g., Figure 2CBH3 shown) and outgassing compounds (e.g., methylamine, ammonia) from substrate 24 combine to form contaminants, such as methylamine-borane and / or ammonia-borane or variants thereof. In some embodiments, compounds formed by outgassing of mask 12 and substrate 24 can react in the gas phase to form solid phase compounds. For example, in some embodiments, methylamine-borane and / or ammonia-borane are formed as a solid phase. The degassed materials and the products of their reactions can provide contaminants that can attach to system 10, including but not limited to chamber sidewalls, reflectors of the optical path, substrate 24, mask 12, and / or other components. In some embodiments, byproducts form solid phase contaminants that are formed on the surface of mask 12, which changes the reflectivity characteristics of that area of ​​the mask, producing defects that interrupt the patterning of the radiation beam. For example, the defect may provide undesirable absorption or reflection, producing defects in the pattern. When the pattern of mask 12 is repeated on substrate 24, a single mask 12 defect can greatly affect the yield of the device formed on substrate 24 because the defect is repeated in substrate 24.

[0044] The present disclosure provides a system and method that, in some embodiments, is directed to reducing outgassing constituents from the mask 12, thereby reducing contamination generated in the system. In order to reduce outgassing constituents from the mask 12, such as reducing the generation of BH3 discussed above, the thermal conditions of the mask 12 are monitored and adjusted by the thermal management techniques discussed herein. For example, the present disclosure recognizes that less outgassing (e.g., BH3 or derivatives) is generated at lower temperatures of the mask 12. Therefore, in some embodiments, outgassing from the mask 12 generated during the lithography process is reduced by managing (e.g., reducing the temperature) the thermal conditions of the mask holder 16, the mask 12 itself, and / or the surrounding environment of the mask 12. Therefore, in some embodiments, thermal management is used to suppress the generation of boron into the environment by reducing the amount of boron released from the absorber and / or reducing the boron-nitride reaction to provide lower outgassing. It should be noted that the nature of EUV lithography and the reflective mask 12 means that a certain percentage of EUV power is absorbed in the EUV mask, increasing the temperature of the EUV mask. The thermal management of the present disclosure recognizes and addresses this increase in temperature.

[0045] In some studies, it has been shown that in a lithography system (such as the system 10 discussed above), more than half of the defects on the EUV mask come from compounds including boron and nitride. Therefore, the implementation of the present embodiment of reducing boron outgassing can be used to benefit the quality of the EUV lithography process by removing reactants of defect-inducing compounds. It should be noted that this discussion is for the purpose of understanding only, and unless specifically mentioned in the following claims, the present disclosure is not bound by any theory or contamination level resulting therefrom.

[0046] refer to Figure 4, a block diagram of a system 400 including a mask 12 and a mask holder (or stage or chuck) 16 is shown. The system 400 may be included in a lithography system, such as the one described above with reference to Figure 1 The lithography system 10 discussed above. In an embodiment, the mask 12 is an EUV mask, substantially similar to the above Figure 2A discussed.

[0047] The mask stage 16 is divided into a plurality of regions or zones 402. The zones 402 are individually adjustable or configurable portions of the mask stage 16. In an embodiment, the zones 402 are individually configurable to provide different thermal controls. In an embodiment, one or more thermal regulation components are provided in each zone 402. Each zone 402 is coupled to a thermal control module 30. In an embodiment, the thermal control module (or simply the controller) 30 provides instructions to a given zone 402 to achieve a desired temperature set point. Each zone 402 may include a component for reducing the temperature of the zone—a thermal regulation component 408—a heat exchanger, a coolant (gas or liquid), a solid cooling module, a heat pipe module, and / or other cooling components. Each zone 402 may also include a temperature sensor 410. In some embodiments, each zone 402 includes a direct temperature sensor 410 such as a thermocouple. Thermocouples include electronic devices that generate a temperature-dependent voltage that can be related to temperature.

[0048] The mask stage 16 may include a single zone 402 or any number of multiple zones 402. In an embodiment, there are two zones 402 in a given stage 16. In other embodiments, an array of zones 402 is provided. Each zone 402 corresponds to a specific physical portion of the stage 16, and therefore corresponds to a specific physical area of ​​the mask 12 held by the stage 16. The thermal control module 30 monitors (e.g., using feedback from sensors 408, 410) the temperature of each zone 402 individually, and also controls the temperature of each zone individually by providing instructions to thermal regulation components 408 in the stage, such as heat exchangers, coolants (gas or liquid), solid cooling modules, heat pipe modules, and thermal regulation components separate from the stage 16, such as gas jets described below.

[0049] To this end, the system 400 also includes one or more gas nozzles (nozzles) 404. In an embodiment, the system 400 includes a plurality of gas nozzles 404, each of which is coupled to the thermal control module 30. The gas nozzles 404 are used to deliver a gas at a certain flow rate. Exemplary gases include, but are not limited to, H, He, Ar, N and / or combinations thereof. In some embodiments, the gas nozzles 404 provide hydrogen. Hydrogen is provided as a suitable gas due to its anti-oxidation, carbon cleaning properties and / or its high EUV transmittance. In an embodiment, the gas nozzles 404 deliver a gas flow for cooling one or more components of the system 400. In some embodiments, the gas nozzles 404 provide a gas flow below room temperature. In an embodiment, there are a plurality of gas nozzles 404, each of which can be individually adjusted or configured by the thermal control module 30. In an embodiment, the gas nozzles 404 are individually configured to provide gases of different flow rates and / or gases of different temperatures. In an embodiment, the thermal control system 30 provides instructions to the gas jets 404 that direct the flow rate and / or gas temperature based on a desired thermal management schedule (eg, cooling) for the mask 12 .

[0050] The system 400 also includes a plurality of sensors 406. The sensors 406 may be IR sensors (also referred to as IR cameras), UV sensors, light sensors, and / or other suitable components. The sensors 406 may be referred to as remote temperature sensing devices because they are not in direct contact with the subject being measured. The plurality of sensors 406 may be used to determine the temperature of the mask 12, the stage 16, and / or one or more zones 402, and / or the temperature in the environment surrounding the mask 12 (shown as a portion of the mask environment 410). In an embodiment, the sensors 406 are infrared (IR) temperature sensors.

[0051] In an embodiment, each zone 402 has an associated remote temperature sensing device, such as an IR sensor, for providing a temperature associated with the zone 402. In an embodiment, each zone 402 has an associated direct temperature sensing device 410, such as a thermocouple, for providing a temperature associated with the zone 402. In an embodiment, the number of each sensor 406 and / or 410 is equal to the number of zones 402. For example, the controller 30 may receive temperature information from a first sensor 406, which the controller 30 may use to provide instructions to a thermal conditioning component and / or gas jets 404 of the first zone 402 to provide thermal cooling of the first zone. The gas jets 404, the thermal conditioning component 408 of the zone 402, and sensors including the remote sensors 406 and the direct sensors 410 (such as thermocouples on the stage 16), together with the controller 30, provide a thermal management system. The thermal management system may be implemented in an EUV lithography system, such as Figure 1In some embodiments, the thermal management system is used to measure and configure or adjust the temperature of the mask 12 so that outgassing from the mask 12 to the mask environment 412 is reduced during the photolithography process.

[0052] Reference now Figure 5 , Figure 6 , Fig. 7A , Fig. 8A and Fig. 9 , respectively, show embodiments of systems 500, 600, 700, 800, and 900 for providing thermal management of a mask or reticle. Systems 500, 600, 700, 800, and 900 are reference Figure 4 An illustrative example of an implementation of system 400 is described. Each of systems 500, 600, 700, 800, and 900 may include additional components and / or may omit one or more components.

[0053] like Figure 5 As shown, system 500 includes mask 12, which can be substantially similar to mask 12 discussed above. In an embodiment, a top layer (ie, Figure 5 In an embodiment, the top layer comprises boron.

[0054] In an embodiment, mask 12 is secured to stage 16 by an electrostatic potential. Other embodiments are possible, including where a clamp secures the reticle to stage 16.

[0055] In an embodiment, the stage 16 can be moved in the X, Y, and / or Z directions by the positioning element 502. In some embodiments, the positioning element 502 includes one or more actuators that can move the stage 16 a specified distance in a specified direction. In some embodiments, the actuator includes a stepper motor, a piezoelectric actuator, a short stroke motor, and / or other components. In some embodiments, the positioning element 502 is coupled to a controller or includes a controller to control one or more stepper motors and / or piezoelectric actuators so that the stage 16 performs the desired movement.

[0056] The stage 16 also includes a thermal conditioning assembly 504. The thermal conditioning assembly 504 may include a heat exchanger, a pipe or channel for providing a coolant, a solid cooling module, a heat pipe module, and / or other thermal cooling components and / or other thermal management components. In an embodiment, the thermal conditioning assembly 504 includes a coolant. The coolant may be a gas or a liquid. In an embodiment, the thermal conditioning assembly 504 operates without a coolant. In the illustrated embodiment, the thermal conditioning assembly 504 is positioned on a side of the positioning element 502 opposite to the mask 12, however other configurations are possible. The thermal conditioning assembly 504 may be substantially similar to the thermal conditioning assembly 16A of the system 10 and / or the thermal conditioning assembly 408 of the system 400.

[0057] Thermocouple 506 is positioned on stage 16. In an embodiment, a thermistor or other temperature measuring device is used instead of, and / or in addition to, thermocouple 506. Thermocouple 506 is used to sense the temperature of stage 16. Thermocouple 506 is coupled to thermal control module 30 and provides thermal control module 30 with temperature data related to the portion of stage 16 on which thermocouple 506 is positioned. Instead of or in addition to thermocouple 506, temperature may be sensed by other direct sensors (e.g., thermistors) or indirect measurement components (such as IR cameras / sensors, UV sensors, light sensors, and / or other suitable components).

[0058] IR module or sensor 508 is positioned adjacent to and at a distance from stage 16. IR module 508 may be substantially similar to the IR module described above with reference to Figure 4 16. In an embodiment, the IR module 508 provides temperature readings of the mask 12, portions of the stage 16, and / or the surrounding environment. The IR module 508 is coupled to the thermal control module 30 and provides temperature data to the thermal control module. Instead of or in addition to the IR module 508, the temperature may be sensed by other indirect sensing components, such as a UV sensor, a light sensor, and / or other suitable components for remotely sensing temperature.

[0059] Based on information received from the thermocouple 506 and the IR module 508, as well as other information (e.g., lithography scan and timing data, mask 12 information, environmental condition data including ambient temperature, lithography parameters (such as described below)), the thermal control module 30 instructs a thermal regulation assembly 504 operably coupled thereto to regulate (e.g., reduce) the temperature of the mask 12, such as by providing additional cooling.

[0060] Figure 6 The system 600 includes many components similar to the system 500, such as the mask 12 and the mask stage 16. However, in the system 600, the stage 16 includes a plurality of thermal adjustment components 602. The thermal adjustment components 602 may include a heat exchanger, a pipe or channel for providing a coolant, and / or other thermal cooling components. In an embodiment of the system 600, two thermal adjustment components 602A and 602B are provided. However, as discussed above with reference to area 402, any number of thermal adjustment components may be provided. In the illustrated embodiment, the thermal adjustment components 602 are positioned on the side of the positioning element 502 opposite to the mask 12, however other configurations are possible. In the illustrated embodiment, the thermal adjustment component 602A is positioned above the first half (e.g., left) of the mask 12, and the thermal adjustment component 602B is positioned above the second half (e.g., right) of the intermediate mask.

[0061] A plurality of thermocouples 506 (506A, 506B) are positioned on the stage 16. In an embodiment, other temperature sensing devices such as thermistors are used instead of or / and in addition to the thermocouples 506. The first thermocouple 506A is positioned on a first portion (e.g., left) of the stage 16, and the second thermocouple 506B is positioned on a second portion (e.g., right) of the stage 16. Thermocouple 506A is used to sense the temperature of a first area of ​​the stage 16; thermocouple 506B is used to sense the temperature of a second area of ​​the stage 16. Each of the thermocouples 506 is coupled to the thermal control module 30 and provides the thermal control module 30 with temperature data associated with the portion (or zone) of the stage 16 on which the thermocouple 506 is positioned.

[0062] A plurality of IR modules 508 are positioned adjacent to the stage 16. The IR modules 508 may be substantially similar to those described above with reference to Figure 4 16 and / or the surrounding environment. In an embodiment, the IR module 508 provides temperature readings of the mask 12, portions of the stage 16, and / or the surrounding environment. In an embodiment, the IR module 508A provides information about a first portion of the mask 12, the stage 16, and / or the surrounding environment; and the IR module 508B provides information about a second portion of the mask 12, the stage 16, and / or the surrounding environment. Each of the IR modules 508A and 508B is coupled to the thermal control module 30 and provides temperature data to the thermal control module 30.

[0063] Based on the information received from the thermocouple 506A, the thermocouple 506B, the IR module 508A, the IR module 508B, and other information (e.g., photolithography scan and timing data, mask 12 information, environmental condition data including ambient temperature), the controller 30 instructs each of the thermal conditioning components 602A and the thermal conditioning components 602 operatively coupled thereto to control the components in a desired manner to regulate the temperature of the first portion and the second portion of the mask 12. Different instructions may be sent to each of the thermal conditioning components 602A and the thermal conditioning components 602B. For example, in an embodiment, the mask 12 information considered by the thermal control module 30 includes the pattern density of the mask 12. In an embodiment, the first portion (e.g., the left) of the mask 12 has a first pattern density, and the second portion (e.g., the right) of the mask 12 has a second pattern density. For example, the first portion may have a greater pattern density than the second portion. In such an embodiment, the controller 30 may provide instructions to the thermal conditioning component 602A to provide additional cooling compared to the instructions provided to the thermal conditioning component 602B. In other words, in some embodiments, thermal control module 30 provides instructions to thermal conditioning component 602A to provide greater cooling than the cooling instructions provided to thermal conditioning component 602B.

[0064] Fig. 7A The system 700 is similar to Figure 6The system 600 discussed in , also includes a mask 12 disposed on a stage 16, which can be substantially similar to that discussed above. The stage 16 also includes a plurality of thermal regulation assemblies 602, and in the illustrated embodiment of the system 700, two thermal regulation assemblies 602A and 602B. In the illustrated embodiment, the thermal regulation assembly 602A is positioned over a portion 12' of the mask 12, and the thermal regulation assembly 602B is positioned over a portion 12" of the mask 12. A plurality of thermocouples 506 and IR modules 508 are included in the system 700. The thermocouples 506 and IR modules 508 can be substantially similar to that discussed above. Although two thermal regulation assemblies 602, two thermocouples 506, and two IR modules 508 are shown, any number is possible.

[0065] The thermal control module or controller 30 is operably coupled to a database 702. The database 702 includes physical structures such as memory devices having inputs and outputs for data transfer in and out. Examples of memory devices include non-volatile memory (NVM) devices such as flash memory devices or ferroelectric random access memory (RAM), volatile memory such as static RAM (SRAM) devices, other suitable memory devices, or combinations thereof.

[0066] Database 702 may include pattern density information associated with mask 12. In an embodiment, the pattern density information is design data related to a device to be manufactured using mask 12. The design data may be information about the design and layout of a chip formed using mask 12, such as design data found in a GDS file. In an embodiment, database 702 includes information about the pattern density of mask 12, such as Figure 7B . In an embodiment, the design data 704 shows that the pattern density at the region 12' is greater than the pattern density at the region 12". In a further embodiment, the features of the design data 704 define an active region, such as a fin of a FinFET transistor. Figure 7C Another exemplary embodiment of design data 704' for forming mask 12 is shown. In an embodiment, design data 704' shows that the pattern density at region 12' is greater than the pattern density at region 12". In a further embodiment, these features define contact elements of a transistor.

[0067] In an embodiment of an EUV mask, the features of the design data 704 may be defined by a patterned absorber layer. The pattern density of the mask 12 may be determined by an absorber (such as described above with reference to FIG. Figure 2A The absorbent layer 206 described above) and the exposed reflective ML (such as also referred to above Figure 2AIn an embodiment, the thermal control module 30 is configured to provide a calculated pattern density based on design data stored in the database 702 .

[0068] Based on the information received from the thermocouple 506, the IR module 508, and the database 702, the thermal control module 30 calculates and sends instructions to each of the thermal conditioning components 602A and 602B operatively coupled thereto. The instructions control the thermal conditioning components in a desired manner so as to adjust (e.g., reduce) the temperature of the first portion 12' and the second portion 12" of the mask 12. Different instructions may be sent to each of the thermal conditioning components 602A and 602B. In an embodiment, the first portion 12' has a first pattern density (see Figure 7B and Figure 7C ), and the second portion 12" has a second pattern density less than the first pattern density (see Figure 7B and Figure 7C ). In such an embodiment, thermal control module 30 may provide instructions to thermal conditioning component 602A to provide additional cooling compared to thermal conditioning component 602B.

[0069] The thermal control module 30 may include an analysis module having various correlation analysis units that analyze correlations between various parameters, such as the correlation between pattern density and heat generation. In some embodiments, the analysis module of the thermal control module 30 identifies that the greater the pattern density of an area of ​​the intermediate mask, the greater the heat generated during the EUV lithography process. In other words, exposure of the first portion 12' generates more heat than exposure of the second portion 12". By providing additional cooling instructions to the thermal regulation component 602A, the system 700 can compensate for the additional heat generated. In an embodiment, the additional cooling is used to reduce the temperature of the first portion 12' and thereby reduce the generation of outgassing such as BH3. It should be noted that the mask 12 is shown as including two areas 12' and 12". However, any number of areas or zones is possible. In some embodiments, the number of areas determines the number of thermocouples 506, IR modules 508 and / or thermal regulation components 602.

[0070] Fig. 8A The system 800 is basically similar to Fig. 7AThe system 700 of the present invention also includes a mask 12 disposed on a stage 16 having a plurality of thermal conditioning assemblies, such as thermal conditioning assemblies 602A and 602B. In the illustrated embodiment, thermal conditioning assembly 602A is positioned over portion 12' of mask 12 and thermal conditioning assembly 602B is positioned over portion 12" of mask 12. A plurality of thermocouples 506 and IR modules 508 are included in system 800 and may be substantially similar to those discussed above. Again, while two thermocouples 506 and two IR modules 508 are shown, any number is possible.

[0071] The thermal control module 30 is operatively coupled to a database 702 that is substantially similar to the database described above with reference to Fig. 7A In an embodiment, as discussed above, database 702 includes design data indicating intermediate mask pattern density. Thermal control module 30 is also operably coupled to database 802. Database 802 includes physical structures, such as memory devices having inputs and outputs for data transfer in and out. Examples of memory devices include non-volatile memory (NVM) devices (such as flash memory devices or ferroelectric random access memory (RAM)), volatile memory (such as static RAM (SRAM) devices), other suitable memory devices, or combinations thereof. Database 802 can be separate from database 702 or integrated with database 702.

[0072] Database 802 may include lithography parameters, such as information about a lithography process and / or mask usage for the lithography process. In an embodiment, database 802 includes information about exposure parameters to be employed by system 800. In an embodiment, database 802 includes exposure times for regions of mask 12. In some embodiments, database 802 includes scanner parameters, such as step conditions (e.g., timing) and scan times in the x or y axis directions. In an embodiment, database 802 includes EUV pulse conditions, such as pulse width (e.g., w nanoseconds), pulse repetition or frequency (e.g., f kHz), power (e.g., p W / cm 2 ) and / or energy (mJ / cm 3 ). Database 802 may contain and / or thermal control module 30 may use to calculate energy (E=Pavg / R) and / or power (e.g., Ppeak=Pavg / R*tau, where R is the repetition rate (e.g., 50kHz) and tau is the pulse duration (e.g., 150nm)) for an EUV lithography process. In an embodiment, database 802 includes the number of EUV pulses required to melt a droplet (e.g., Sn), which affects the temperature profile of the system. In an embodiment, database 802 includes a temperature profile indicating the highest temperature during an associated scan condition (discussed below).

[0073] Based on the information received from the thermocouple 506, the IR module 508, the database 702, and the database 802, the thermal control module 30 calculates and sends instructions to each of the thermal adjustment components 602A and the thermal adjustment components 602B operatively coupled thereto to control the components in a desired manner so as to adjust the temperature of the first portion 12' and the second portion 12" of the mask 12 during exposure. Different instructions may be sent to each of the thermal adjustment components 602A and the thermal adjustment components 602B. As discussed above, in an embodiment, the thermal control module 30 receives information from the database 702 that the intermediate mask portion 12' has a first pattern density (see Figure 7B and Figure 7C ), and the intermediate mask portion 12" has a second pattern density less than the first pattern density (see Figure 7B and Figure 7C ). The pattern density can be used by the analysis module to determine cooling requirements (eg, greater pattern density requires greater cooling).

[0074] In an embodiment, the thermal control module 30 receives information including temperature profile data associated with a lithography process using the mask 12 in the system 800 from the database 802. In an embodiment, the thermal control module 30 receives information from the database 802, which the thermal control module 30 uses to calculate the temperature profile data associated with the lithography process using the mask 12 in the system 800. In an embodiment, the thermal control module 30 recognizes that the lithography process to be performed using the intermediate mask 12 has a scanner step condition of n milliseconds of stepping. The analysis module of the thermal control module 30 can determine the thermal condition caused by n milliseconds (e.g., cooling), and / or receive the thermal condition caused by n milliseconds from the database 802. In an embodiment, the thermal control module 30 recognizes that the lithography process to be performed using the mask 12 has a scan duration of m milliseconds (e.g., received from the database 802). The analysis module of the thermal control module 30 can determine the thermal condition caused by m milliseconds (e.g., heating), and / or receive the thermal condition caused by m milliseconds from the database 802.

[0075] In an embodiment, the thermal control module 30 receives temperature profile data from the database 802, and / or an analysis module of the thermal control module 30 can generate temperature profile data (e.g., through simulation) using data from the database 802. The temperature profile data shows the thermal conditions of the mask or a portion thereof over time when the mask or a similarly configured mask is exposed to a lithography process defined by the parameters stored in the database 802. In an embodiment, the thermal control module 30 receives previously acquired data from the database 802 (e.g., by the system 800) showing temperature readings over time when the mask 12 or a similarly configured mask is exposed. In an embodiment, the thermal control module 30 includes an analysis module for generating a temperature profile including the temperature over time when the mask 12 is exposed. Figure 8B 8. Example temperature profile data 804 is shown in FIG. The temperature profile data 804 can be used by an analysis module of the thermal control module 30 to determine cooling requirements over a given time during an exposure process. In an embodiment, the thermal control module 30 provides instructions to the thermal conditioning component 602A to provide a first cooling performance during a first duration of the EUV scan of the mask 12, and to provide a second cooling performance during a second duration after the first duration of the EUV scan of the mask 12.

[0076] Therefore, in the system 800, the thermal control module 30 may include an analysis module including various correlation analysis units that analyze correlations between various parameters, such as correlations between pattern density and heat generation, and implement into analysis data thereof associated with a temperature profile (e.g., collected through simulation, experimental results, previous product runs, similar reticle, etc.) associated with scanning conditions of the mask 12. In some embodiments, the analysis module of the thermal control module 30 identifies that the greater the pattern density of a region of the reticle, the greater the heat generated during the EUV process. In other words, exposure of intermediate mask portion 12' generates more heat than exposure of intermediate mask portion 12". By providing additional cooling instructions to thermal conditioning component 602A, the system can compensate for the additional generated heat. In some embodiments, the analysis module of thermal control module 30 identifies that a higher temperature of mask 12 is provided during a specific time during the EUV process. By providing additional cooling instructions to thermal conditioning component 602, the system can compensate for the additional generated heat during the appropriate time. In an embodiment, the cooling instructed by thermal control module 30 is used to reduce the temperature of mask 12 and thereby reduce the generation of outgassing such as BH3.

[0077] Fig. 9 The system 900 is similar to Fig. 8AThe system 800 includes a mask 12 disposed on a stage 16, and the stage 16 includes thermal conditioning components 602A and 602B. In the illustrated embodiment, the thermal conditioning component 602A is positioned over a portion 12' of the mask 12, and the thermal conditioning component 602B is positioned over a portion 12" of the mask 12. However, the mask 12 can be divided into any number of portions or regions.

[0078] A plurality of thermocouples 506 and IR modules 508 are included in the system 900. The thermocouples 506 and IR modules 508 can be substantially similar to those discussed above. Although two thermocouples 506 and two IR modules 508 are shown, any number is possible. The thermal control module 30 is operably coupled to the database 702 and the database 802, and the database 702 is substantially similar to those discussed above with reference to FIG. Fig. 7A , Figure 7B , Figure 7C As discussed above, database 802 is substantially similar to Fig. 8A and Figure 8B In an embodiment, as discussed above, database 702 includes design data indicating mask pattern density. In an embodiment, as discussed above, database 802 includes temperature profile data indicating a temperature profile to be expected when scanning mask 12 using system 900. One or more of these components may be omitted in an embodiment of system 900.

[0079] The system 900 also shows a first gas flow 902 and a second gas flow 904. In an embodiment, the first gas flow 902 is provided from a first gas jet 902A and the second gas flow 904 is provided from a second gas jet 902B. The gas jets may be substantially similar to those described above with reference to Figure 4 The gas jet 404 discussed. The first gas stream 902 is provided at a first distance from the mask 12. The second gas stream 904 is provided at a second distance from the mask 12, which second distance may be greater than the first distance. In an embodiment, one or more of the gas streams 902, 904 include laminar flow in the x-direction. The gas streams 902 and 904 may be the same gas (e.g., hydrogen), but this is not required. The flow rate of the gas stream 902 may be different from the flow rate of the gas stream 904.

[0080] In addition, the temperature of gas stream 902 may be different from the temperature of gas stream 904. For example, in an embodiment, gas stream 902 may be about 2°C to about 20°C cooler than gas stream 904. In an embodiment, both gas stream 902 and gas stream 904 are below ambient temperature (e.g., below about 22°C). In an embodiment, gas stream 902 and / or gas stream 904 are greater than about 0°C. In an embodiment, gas stream 904 is about room temperature (e.g., about 22°C), and the temperature of gas stream 902 is lower than the temperature of gas stream 904, such as at least 3°C ​​lower). In an embodiment, gas streams 902 and 904 are provided at a temperature at which condensation does not occur. In some embodiments, the intermediate mask chuck pressure is such that condensation does not occur when the provided gas streams 902, 904 are at a reduced temperature. In an embodiment, the intermediate mask chuck pressure may be between about 5Pa and 100Pa. In a further embodiment, the gas stream includes a gas having a phase transition triple point provided at about 1kPa and 0°C. The gas temperature may be maintained so that the gas stream remains in a gas phase.

[0081] The gas streams 902 and 904 and the gas jets 902A and 902B are controlled by the thermal control module 30. In an embodiment, the thermal control module 30 provides instructions related to the flow rate and / or temperature of the gas streams 902 and 904. The thermal control module 30 uses information provided from the database 702 and / or 802, the thermocouple 506, and the IR module 508 to determine the instructions for the gas streams 902 and 904. The thermal control module 30 can determine the desired cooling of the mask 12 achieved by the combination of the gas streams 902, 904 and the thermal conditioning assembly 602.

[0082] Therefore, in the system 900, the thermal control module 30 may include an analysis module that provides various correlation analysis units that analyze correlations between various parameters, such as correlations between pattern density and heat generation, and are implemented in its analysis data of previous temperature profiles (e.g., collected through simulations, experimental results, previous product runs, similar reticle, etc.) associated with scanning conditions of the mask 12. In some embodiments, the analysis module of the thermal control module 30 identifies that the greater the pattern density of a region of the reticle, the greater the heat generated during the EUV process. In other words, exposure of intermediate mask portion 12' generates more heat than exposure of intermediate mask portion 12". By providing additional cooling instructions to thermal conditioning assembly 602 and / or gas jets 902A and 902B providing gas flows 902 and 904, respectively, the system can compensate for the additional generated heat. In some embodiments, the analysis module of thermal control module 30 identifies that greater heat of mask 12 is generated during a specific time during the EUV process. By providing additional cooling instructions to thermal conditioning assembly 602 and / or gas jets 902A and 902B providing gas flows 902 and 904, respectively, the system can compensate for the additional generated heat at the appropriate time. In an embodiment, the cooling instructed by controller 30 is used to reduce the temperature of mask 12 and thereby reduce the generation of outgassing such as BH3.

[0083] Fig.10 An embodiment of a lithography tool 1000 is shown which is simplified for ease of understanding. In an embodiment, the lithography tool 1000 is an EUV lithography tool. The lithography tool 1000 may be substantially similar to the one described above with reference to FIG. Figure 1 The system 10 is described. Additional components may be added to the lithography tool 1000, and components may be omitted.

[0084] The lithography tool 1000 includes a radiation source 14 that provides a radiation beam 18. In an embodiment, the radiation beam 18 provided by the source 14 has an EUV wavelength. The radiation enters a microenvironment 1004 within a main chamber 1002 of the tool 1000. Within the microenvironment 1004, there is an illuminator assembly 1008 and a projection optics (or POB) assembly 1010. The illuminator assembly 1008 may include a field facet and a pupil facet, and in some embodiments may be substantially similar to the above-referenced embodiment. Figure 1 The projection optics (or POB) assembly 1010 may include a plurality of mirrors and in some embodiments may be substantially similar to the illuminator 20 discussed above. Figure 1 The projection optical element 22 is discussed.

[0085] The microenvironment 1004 defines and contains an optical system or path for the radiation 18. The components 1003 defining the microenvironment may include components that calibrate, direct, modify, and / or contain the radiation 18. The microenvironment 1004 may be a vacuum environment.

[0086] A plurality of gas nozzles are provided in tool 1000. A first gas nozzle 1012, also referred to as a y-nozzle, is provided near the bottom of mask 12. In some embodiments, gas nozzle 1012 is included in or within a reticle masking (REMA) blade (not shown). A gas flow 1012A is provided from nozzle 1012. Gas flow 1012A may be substantially similar to Figure 4 The airflow of the nozzle 404 in the system 400, and / or the airflow 1012A can be substantially similar to the above referenced Fig. 9 904 is depicted. Exemplary gases for the gas stream 1012A provided from the gas jet 1012 include, but are not limited to, H, He, Ar, N, and / or combinations thereof. As discussed above, in embodiments, the gas stream 1012A may be below room temperature.

[0087] The gas nozzle 1014 is disposed at a position further from the bottom of the mask 12. The gas nozzle 1014 may be adjacent to or embedded in the component 1003 defining the microenvironment. A gas flow 1014A is provided from the nozzle 1014. Exemplary gases provided from the gas nozzle 1014 include, but are not limited to, H, He, Ar, N, and / or combinations thereof. In an embodiment, the gas flow 1014A is similar to Figure 4 The airflow from the nozzle 404 in the system 400 and / or the above reference Fig. 9 As discussed above, in embodiments, airflow 1014A may be below room temperature. In some embodiments, airflow 1014A is below room temperature but above the temperature of airflow 1012A. In some embodiments, airflow 1014A is below room temperature but at least 3°C ​​above the temperature of airflow 1012A. In embodiments, airflow 1014A is provided in a channel of component 1003 and released into microenvironment 1004, where airflow 1014A generates upward and downward vertical flows, and in some embodiments, the upward vertical flow is greater than the downward vertical flow.

[0088] The mask 12 is positioned so that the radiation beam is incident on its surface; the mask 12 is held by a mask stage 16. In some embodiments, the mask stage 16 includes a thermal adjustment assembly and / or a thermal sensor, such as discussed above.

[0089] Fig.10 The portion of the mask 12 adjacent to the mask 12 may be referred to as an intermediate mask microenvironment. The intermediate mask microenvironment includes the mask or intermediate mask 12, the mask stage or chuck 16, and thermal conditioning components, such as those described above with respect to Figure 5 , Figure 6, Fig. 7A , Fig. 8A and Fig. 9 For example, the thermal conditioning assembly may provide cooling for one or more regions of the stage 16 , and therefore, the mask 12 .

[0090] The reticle microenvironment also includes components, such as a reticle masking blade (REMA blade), that calibrate, direct, modify, and / or contain radiation 18. In some embodiments, a gas nozzle, such as first gas nozzle 1012, is positioned in the REMA blade.

[0091] Reference now Fig.11 , a method 1100 for providing a thermal control plan is shown. The thermal control plan provided by the method 1100 can be provided to a lithography tool (such as Figure 1 The method 1100 may be implemented by a lithography system 10 and / or by a lithography tool. Figure 1 The discussion is performed by a thermal control module 30 , also referred to as a controller.

[0092] Method 1100 includes operation 1202, wherein pattern density information is received. In an embodiment, the pattern density is collected from a design file associated with the intermediate mask. The design file may be provided in a GDS file format. In an embodiment, the pattern density information may be depicted by regions or zones of the intermediate mask. Figure 7B and Figure 7C Exemplary embodiments of pattern density information are described.

[0093] Method 1100 includes operation 1204, in which lithography parameters including mask usage information are received. Exemplary parameters include parameters such as equivalent power, exposure time, stepping conditions, scanning time, pulse frequency and width, ambient temperature, intermediate mask edge temperature, stepping duration, and / or other lithography parameters that affect thermal conditions of the intermediate mask and / or its surroundings. In an embodiment, 235 W / cm 2 In an embodiment, a middle mask edge temperature is provided that is set to about 24°C. In an embodiment, a step duration is provided that is set to about 60-75 milliseconds. In an embodiment, the lithography parameters also include sensor data from sensors positioned on or around the lithography tool, such as temperature data from thermocouples, IR cameras / sensors, UV sensors, light sensors, and / or other suitable components.

[0094] The method 1100 includes an operation 1206 in which a lithography process is simulated using lithography parameters and pattern density information to determine a thermal profile. The analysis module includes various correlation analysis units that analyze correlations between various parameters, such as correlations between pattern density and thermal conditions of the intermediate mask and / or its surroundings during exposure, correlations between lithography parameters and thermal conditions of the intermediate mask during exposure, and other correlations. Figure 8B Examples of generated thermal profiles are described in . A simulation may show the maximum temperature at one or more times during a simulated lithography process (see Figure 8B ). In an embodiment, the maximum temperature after the first scan is between about 280°C and 350°C, and the maximum temperature after the second scan is between 380°C and 450°C, and the field stepping positioning can occur between the first scan and the second scan. In an embodiment, the simulation can provide an amount of cooling during the field stepping. In an embodiment, cooling of about 150°C and 300°C is provided. In an embodiment, cooling of between about 25% and 75% of the temperature increase provided by the previous scan is provided during the field stepping. The analysis providing the thermal profile can be performed by a controller such as the thermal control module 30.

[0095] The analysis of operation 1206 may also include generating a correlation between the generated thermal profile and outgassing of a component (e.g., a B derivative such as BH3). In an embodiment, the analysis module utilizes simulations, experimental data, and / or chemical reaction analysis to determine, for example, the level of outgassing generated from an absorber layer that defines a pattern density for a given thermal profile. In an embodiment, the analysis module identifies that higher thermal profile temperatures provide greater outgassing.

[0096] The method 1200 includes an operation 1208 in which a thermal management action is determined. The analysis module may generate one or more thermal management actions to reduce the temperature of the mask and / or its surroundings during the lithography process. In an embodiment, the thermal management action includes setting one or more thermal regulation components (e.g., gas jets) positioned in the mask stage and / or remote from the intermediate mask. In an embodiment, the thermal management action is to send instructions to the thermal regulation component, which may be substantially similar to the thermal regulation component described above with reference to FIG. Figure 4 The thermal regulation component 408 or Figures 5 to 9The thermal regulation components 504, 602 discussed above. For example, in some embodiments, the thermal regulation components include a heat exchanger, a pipe or channel for providing a coolant, a solid cooling module, a heat pipe module and / or other thermal cooling components in the intermediate mask stage or chuck and / or other thermal management components. In an embodiment, the thermal management action is to send instructions to the thermal regulation components of one or more gas nozzles, including setting the temperature and / or flow rate of the gas flow from the gas nozzles. The gas nozzles can be substantially similar to those discussed above with reference to gas flow 902, 904 and / or gas nozzles 1012, 1014. The thermal management action may include instructions to adjust the thermal regulation components during a given lithography process. For example, the thermal control plan can reduce the gas nozzle temperature during a scanning process and / or provide additional cooling in the thermal regulation components of the mask stage during a lithography process.

[0097] In an embodiment, rather than issuing instructions directly, method 1100 inputs the determined thermal management actions into the simulation at operation 1206 to determine the thermal profile in an iterative process.

[0098] The method 1100 includes an operation 1210 in which thermal control schedule instructions are implemented during a photolithography process. This embodiment may include setting, adjusting or regulating thermal regulation components of a mask stage and / or gas jets before and during a photolithography process.

[0099] It should be noted that in some embodiments, Fig.11 The method 1100 provides a thermal control plan before performing a lithography process. In some embodiments, the thermal control plan is developed during the lithography process. In one embodiment, the lithography parameters received in operation 1204 include real-time data of the lithography process, such as temperature readings from sensors. Exemplary sensors include thermocouples (such as thermocouples 506A, 506B discussed above) and / or remote sensors (such as IR modules or sensors 508A, 508B discussed above). The real-time data can be used to determine the thermal control plan as discussed in operation 1210. In some embodiments, the method 1100 is performed for each zone of the intermediate mask.

[0100] Fig.12 A flow chart of a method 1300 for performing a photolithography process is shown. The method 1300 may be referred to above. Figure 1 The described lithography system 10 and / or other systems and tools disclosed herein may be implemented.

[0101] Method 1300 includes an operation 1302 of loading a mask or intermediate mask into a lithography system. In an embodiment, an EUV photomask is loaded into an EUV lithography system, which is used to perform an EUV lithography exposure process. The photomask may be substantially similar to mask 12 discussed above. The mask includes an IC pattern to be transferred to a target substrate. Operation 1302 may also include various steps, such as fixing the photomask on a mask stage and performing alignment.

[0102] The method 1300 includes loading a target substrate, such as a semiconductor wafer, into a photolithography system at operation 1304. The target substrate is coated with a photoresist layer. In an embodiment, the photoresist layer is sensitive to EUV radiation.

[0103] The method 1300 includes an operation 1306 of providing and implementing a thermal control plan. The thermal control plan may be provided by a thermal control module, such as the thermal control module 30 discussed above. Providing the thermal control plan includes receiving information about the intermediate mask, including lithography parameters used by the mask, and the temperatures of various components. The thermal control plan utilizes this information to implement a thermal management plan that includes a thermal management action that provides guidance to a thermal conditioning component to reduce the temperature of one or more components of the intermediate mask or lithography system. In some embodiments, the thermal control plan determines a thermal management action that sends instructions to a thermal conditioning component, such as a heat exchanger in a mask holder. In some embodiments, the thermal control plan determines a thermal management action that sends instructions to a thermal conditioning component of one or more gas jets of the lithography system. Thus, implementation of the thermal control plan includes adjusting one or more components (e.g., heat exchangers, gas jets).

[0104] In an embodiment, a thermal control plan is provided by an operation such as that described above with reference to Fig.11 The operations shown in the method 1100 described above are described. In an embodiment, the thermal control plan is updated during the lithography process based on feedback such as received from a temperature sensor. In other words, operation 1306 may occur multiple times during the execution of operation 1308. The thermal control plan may be determined, adjusted, and implemented for the entire intermediate mask. In other embodiments, the thermal control plan may be determined, adjusted, and implemented for individual regions of the intermediate mask.

[0105] Fig.12 An embodiment of a plurality of steps that may be included in operation 1306 of forming a thermal control plan is shown. In step 1306A, data of the lithography system, such as mask usage, is collected. This data may be substantially similar to that described above with reference to Fig. 9 In step 1306B, data of the mask pattern is collected. In an embodiment, the data includes pattern density. The data may be substantially similar to the above reference Fig. 8A The data described in the database 802 and / or Figure 7B , Figure 7C Data shown. In step 1306C, thermal information is collected. The thermal information may include receiving a temperature from a first temperature sensing device such as a direct temperature sensing device (e.g., a thermocouple). The first received temperature may be associated with the mask holder, for example, from a thermocouple positioned directly on the mask holder. The thermal information may include receiving a temperature from a second temperature sensing device such as a remote temperature sensing device (e.g., an IR sensor). The second received temperature may be associated with the intermediate mask, for example, from a remote temperature sensing device directed to the intermediate mask. In some embodiments, a temperature reading is received from each of a plurality of zones of the intermediate mask. In step 1306D, a thermal control plan is formulated. The thermal control plan may be substantially similar to that discussed above and include instructions for thermal regulation components such as components in the mask holder (e.g., heat exchangers, coolants) and / or gas nozzles (e.g., delivering cooling gas). One or more of steps 1306A, 1306B, 1306C, and 1306D may be omitted.

[0106] Method 1300 includes operation 1308 by performing a lithography exposure process on a wafer in a lithography system. In an embodiment, operation 1308 is an EUV lithography operation, and the laser and the tin droplet generator are synchronized (specifically, the laser pulse and the tin droplet generation are synchronized) by a suitable mechanism (such as a control circuit with a timer) to control and synchronize both. The synchronized laser excites the target material droplets and generates plasma, thereby generating EUV radiation. During operation 1308, the generated EUV radiation is irradiated on a photomask (through an illuminator such as illuminator 20) and further projected on a photoresist layer coated on the wafer (through a POB such as optical element 22), thereby forming a latent image on the photoresist. In an embodiment, the lithography exposure process is implemented in a scanning mode.

[0107] In particular, during the lithography exposure process, the various instructions of the thermal management plan formulated in operation 1306 can be implemented simultaneously or overlapping with the lithography exposure process. For example, the method 1300 can continue at operation 1306 to collect data (e.g., temperature readings via thermocouples, IR sensors, etc.) via a temperature sensor, and analyze the collected data via an analysis module to execute and / or adjust the thermal control plan during exposure of the mask. For example, in an embodiment, during the lithography process (e.g., during exposure of the mask to EUV), the temperature is received from a sensor (e.g., a thermocouple or an indirect sensor such as an IR sensor) on the mask holder 16.

[0108] In an embodiment, the thermal management of method 1300 is used to reduce the temperature of the intermediate mask and / or its surrounding environment. The reduction in temperature can provide reduced outgassing from the intermediate mask layer, such as atoms (e.g., B) from the absorber layer. In an embodiment, due to the thermal management, outgassing of boron is reduced. In some embodiments, the reduction in outgassing of boron reduces the available reactants for forming contaminant compounds in the system, including the above Figure 3 discussed in .

[0109] Method 1300 may include other operations to complete the photolithography patterning process. For example, method 1300 may include operation 1310, which forms a photoresist pattern having a plurality of openings defined thereon on a substrate by developing the exposed photoresist layer. In one example, the photoresist layer is positive; the exposed portion of the photoresist layer is removed by a developer. In another example, the photoresist layer is negative; the exposed portion of the photoresist layer remains; and the unexposed portion is removed by a developer.

[0110] Method 1300 may also include other operations, such as various baking steps. As an example, method 1300 may include a post-exposure baking (PEB) step between operations 1310 and 1312. Method 1300 may also include other operations, such as operation 1312 of performing a manufacturing process on a wafer through an opening of a photoresist pattern provided by method 1300. In one example, the manufacturing process includes applying an etching process to a semiconductor substrate or a material layer thereon using the photoresist pattern as an etching mask. In another example, the manufacturing process includes performing an ion implantation process on a semiconductor substrate using the photoresist pattern as an implantation mask. After operation 1312, the photoresist layer may be removed by wet stripping or plasma ashing.

[0111] Thus, the present disclosure provides an exemplary lithography system having a thermal control module and a method of performing lithography, which implements thermal control management by providing thermal management actions or instructions to thermal regulation components such as gas jets and / or mask stage components such as heat exchangers or coolant pipes / channels. In some embodiments, the thermal control management takes into account pattern density differences on the mask. In some embodiments, the thermal control management takes into account mask usage such as scan / step time. The thermal control management can be used to sufficiently reduce the temperature of the intermediate mask and / or its surrounding environment to reduce outgassing of material from the intermediate mask (e.g., an absorber layer). The reduction in outgassing can provide a reduced intermediate mask defect rate by reducing contaminants in the system.

[0112] In one example aspect, the present disclosure provides a method for extreme ultraviolet (EUV) lithography. The method includes collecting thermal data associated with an intermediate mask during a lithography process. And using the thermal data to determine a thermal management action, wherein the thermal management action includes providing instructions to a thermal regulation component to cool the intermediate mask.

[0113] In a further embodiment, the method includes receiving design data associated with a pattern on a reticle, and using the design data to determine a thermal management action. In an embodiment, the method includes receiving a temperature reading from a thermocouple and receiving a temperature reading from an IR sensor. In some embodiments, the thermal management action includes providing instructions to a thermal regulation component of a first gas jet to provide a gas flow. In an embodiment, the gas flow is below about 22°C. In some embodiments, the method provides a thermal management action including providing instructions to a thermal regulation component of a second gas jet to provide another gas flow. The gas flow from the first gas jet may be at least 3°C ​​cooler than the gas flow from the second gas jet. In an embodiment, the thermal management action is to provide instructions to a thermal regulation component of a heat exchanger in a reticle chuck used in a lithography process. The method may include providing instructions to a heat exchanger such that the instructions are provided to a first component having a coolant in a first portion of the reticle chuck, and to a second component having a coolant in a second portion of the reticle chuck. The first component and the second component are individually controllable.

[0114] In another example aspect, a method of performing lithography is performed. The method includes providing a mask to a mask holder of a lithography tool, and providing a target substrate to a wafer stage of the lithography tool. A radiation beam is transmitted from a source of the lithography tool. The transmitted radiation beam is reflected off the mask. The method continues to include providing the reflected radiation beam to the target substrate. During the transmission of the radiation beam, thermal control management is performed. The thermal control management includes receiving a temperature associated with the mask holder and receiving a temperature associated with the mask. An output of a thermal regulation component is modified based on the received temperature.

[0115] In a further embodiment, modifying the output of the thermal conditioning assembly includes providing an airflow having a temperature below 22°C. In some embodiments, modifying the output of the thermal conditioning assembly also includes providing a coolant to the mask holder. In an embodiment, the method includes receiving a first temperature associated with a first area of ​​the mask holder and a second temperature associated with a second area of ​​the mask holder. The temperature can be received from an IR sensor. In some embodiments, performing thermal control management also includes receiving a pattern density of the mask and determining an initial output of the thermal conditioning assembly based on the pattern density.

[0116] In yet another example aspect, the present disclosure provides an extreme ultraviolet (EUV) lithography system. The system includes a reticle holder, a temperature sensor, a first thermal adjustment component, a second thermal adjustment component, and a control module. The first thermal adjustment component is used to reduce the temperature of the reticle in the reticle holder. The second thermal adjustment component is used to provide an airflow adjacent to the reticle in the reticle holder. The control module is coupled to the temperature sensor, the first thermal adjustment component, and the second thermal adjustment component.

[0117] In an embodiment, the temperature sensor includes a first thermocouple located on a first region of the intermediate mask holder and a second thermocouple located on a second region of the intermediate mask holder. In an embodiment, the temperature sensor further includes at least one remote temperature sensing device. In an implementation, the at least one remote temperature sensing device includes a first IR sensor and a second IR sensor, the first IR sensor being used to sense a temperature of a first region of the intermediate mask in the intermediate mask holder and the second IR sensor being used to sense a temperature of a second region of the intermediate mask in the intermediate mask holder. In an embodiment, the system further includes another thermal conditioning component adjacent to the first thermal conditioning component, wherein the other thermal conditioning component is used to cool the first region of the intermediate mask in the intermediate mask holder, and the first thermal conditioning component is used to cool the second region of the intermediate mask in the intermediate mask holder.

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

Claims

1. A method for extreme ultraviolet (EUV) lithography, the method comprising: collecting thermal data associated with a reticle during a lithography process; receiving design data associated with a pattern on the intermediate mask; as well as A thermal management action is determined using the thermal data and the design data, wherein the thermal management action includes providing instructions to a thermal regulation component to cool the reticle.

2. The method according to claim 1, wherein: The design data includes pattern density.

3. The method according to claim 1, wherein: Collecting the thermal data includes: receiving a temperature reading from a thermocouple; and Receives temperature readings from an infrared (IR) sensor.

4. The method according to claim 1, wherein: The thermal management action is providing the instruction to the thermal regulation component of the first gas jet to provide gas flow.

5. The method according to claim 4, wherein: The air flow was below 22°C.

6. The method according to claim 4, wherein: The thermal management actions also include providing the instructions to the thermal regulation component of the second gas outlet to provide another gas flow.

7. The method according to claim 6, wherein: The gas flow from the first gas jet is at least 3°C ​​cooler than the gas flow from the second gas jet.

8. The method according to claim 1, wherein: The thermal management action is providing the instruction to the thermal regulation component of the heat exchanger in the reticle chuck used in the photolithography process.

9. A method of performing photolithography, wherein: The method comprises: providing the mask to a mask holder of a lithography tool; providing a target substrate to a wafer stage of the lithography tool; transmitting a radiation beam from a source of the lithography tool, wherein the transmitted radiation beam reflects off the mask; providing the reflected radiation beam to the target substrate; and During the delivery of the radiation beam, thermal control management is performed, wherein the thermal control management comprises: receiving a temperature associated with the mask holder, receiving a temperature associated with the mask, An output of the thermal conditioning component is modified based on the received temperature, wherein modifying the output includes determining an airflow.

10. An extreme ultraviolet (EUV) lithography system comprising: a reticle holder; Temperature sensor; a first thermal adjustment component located in the intermediate mask holder, wherein the first thermal adjustment component is used to reduce the temperature of the intermediate mask in the intermediate mask holder; a second thermal conditioning assembly spaced a distance from the reticle holder, wherein the second thermal conditioning assembly is configured to provide airflow adjacent to the reticle in the reticle holder; and A control module is coupled to the temperature sensor, the first thermal regulation component, and the second thermal regulation component.

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