Method for an extreme ultraviolet lithography, method of performing lithography and extreme ultraviolet lithography system

Abstract

This disclosure provides a method for a lithography system comprising one or more thermal sensors that provide feedback to a thermal management controller. The thermal management controller provides instructions to thermally modulated components, such as heat exchangers and gas injectors, to provide cooling for photomasks used in the lithography system.

Description

Technical Field

[0001] This disclosure relates to extreme ultraviolet (EUV) lithography methods, methods for performing lithography, and EUV lithography systems. Prior Technology

[0002] The semiconductor integrated circuit (IC) industry has experienced exponential growth. Technological advancements in IC materials and design have yielded generation after generation of ICs, each smaller and more complex than the last. Throughout IC development, functional density (the number of interconnects per die area) has generally increased, while geometry (the smallest component (or line) that can be created using manufacturing processes) has decreased. This scaling down of processes typically benefits production efficiency and reduces associated costs. However, this shrinkage also increases the complexity of IC processes and manufacturing.

[0003] To achieve these advancements, similar developments are needed in IC fabrication processes and manufacturing. For example, there is a growing demand for higher-resolution lithography processes. One such lithography technique is extreme ultraviolet (EUV) lithography. EUV lithography uses a scanner that employs light in the extreme ultraviolet region, with wavelengths of approximately 1-100 nm. EUV scanners use reflective optics instead of refractive optics, i.e., mirrors instead of lenses. However, while existing lithography techniques are generally sufficient for their intended purpose, they are not entirely satisfactory in every aspect. Summary of the Invention

[0004] This disclosure relates to an extreme ultraviolet (EUV) lithography method, which includes: collecting thermal data associated with a photomask during a lithography process; receiving design data associated with a pattern on the photomask; and using the thermal data and the design data to determine a thermal management measure, wherein the thermal management measure includes providing an instruction to a thermal conditioning component to cool the photomask.

[0005] This disclosure also relates to 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 is reflected by 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, and modifying an output of a thermal conditioning component based on the received temperature, wherein modifying the output includes determining an airflow.

[0006] This disclosure also relates to an extreme ultraviolet lithography system, comprising: a photomask support; a temperature sensor; a first thermal regulation component in the photomask support, wherein the first thermal regulation component is operable to reduce a temperature of a photomask in the photomask support; a second thermal regulation component spaced apart from the photomask support, wherein the second thermal regulation component is operable to provide an airflow adjacent to a photomask in the photomask support; and a control module coupled to the temperature sensor, the first thermal regulation component, and the second thermal regulation component. Simple Explanation of the Diagram

[0007] The various features disclosed herein can be best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that, in accordance with industry standard practice, the features are not drawn to scale. In fact, for clarity of discussion, the dimensions of the features can be arbitrarily increased or decreased.

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

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

[0010] Figure 3 illustrates the molecular structures and interactions that occur in a lithography environment according to some theories disclosed herein.

[0011] Figure 4 is a block diagram of an embodiment of a lithography system with a thermal control module according to some embodiments of the present disclosure.

[0012] Figures 5, 6, 7A, 8A and 9 are schematic diagrams of different embodiments of the features of thermal control management according to some of the states disclosed herein.

[0013] Figures 7B and 7C are illustrations of exemplary design data that can be used in various forms disclosed herein.

[0014] Figure 8B is an illustration of an exemplary thermal profile implemented in the various samples disclosed herein.

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

[0016] Figure 11 is a flowchart of an embodiment of a method for developing a thermal control plan according to some of the states disclosed herein.

[0017] Figure 12 is a flowchart of an embodiment of performing a lithography process including thermal management according to the present disclosure. Implementation

[0018] The following disclosure provides numerous different embodiments or examples for implementing different features. Component symbols and / or letters may be repeated in the various examples described herein. This repetition is for simplicity and clarity and does not in itself define the relationship between the various embodiments and / or configurations disclosed. Furthermore, specific examples of components and configurations are described below to simplify this disclosure. Of course, these are merely examples and are not intended to be limiting. For example, in the following description, forming a first feature on or over a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. Furthermore, in this disclosure, the formation on, connected to, and / or coupled to another feature may include embodiments in which the features are formed in direct contact, and may also include embodiments in which additional features may be formed, such that the features may not be in direct contact.

[0019] Additionally, element symbols and / or letters may be repeated in various examples in this disclosure. Such repetition is for simplicity and clarity and does not in itself define the relationship between the various embodiments and / or configurations discussed. Furthermore, in the following disclosure, the formation of features on, connected to, and / or coupled to another feature may include embodiments in which features are formed in direct contact, and may also include embodiments in which additional features can be formed, such that features do not need to be in direct contact. Furthermore, spatially related terms, such as “down,” “up,” “horizontal,” “vertical,” “above,” “on,” “below,” “under,” “under,” “top,” “bottom,” and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.), are used for the convenience of understanding the relationship between one feature and another in this disclosure. Spatially related terms are intended to cover different orientations of the device containing the features. Furthermore, when using terms such as "about" or "approximately" to describe numbers or ranges of numbers, the term is intended to cover numbers within a reasonable range that includes the described number, such as within + / - 10% of the described quantity, or other values ​​understood by one of ordinary skill in the art. For example, the term "about 5 nm" covers a size range from 4.5 nm to 5.5 nm.

[0020] This disclosure includes embodiments of extreme ultraviolet (EUV) lithography apparatus integrated with an EUV control system designed to monitor, analyze, and / or control the EUV lithography apparatus and methods for enhancing performance through thermal management. This disclosure also includes a method for using a control system to monitor thermal conditions and actively tune and control various states of the EUV lithography apparatus, thereby improving the lithography process in some embodiments when the EUV lithography apparatus is used in integrated circuit (IC) manufacturing. Specifically, this method and the EUV control system are associated with EUV lithography apparatuses used for patterning IC structures in advanced technology nodes. According to various embodiments, the IC structure may include field-effect transistors (FETs), FinFETs, or multi-gate devices, such as gate-all-around (GAA) devices.

[0021] However, while this disclosure provides exemplary systems and methods for implementing EUV lithography, it should be understood that lithography utilizing other wavelengths and other process steps can benefit from the variations of this disclosure. Therefore, this disclosure includes thermal management of other systems, and other lithography systems.

[0022] Figure 1 is a block diagram of a lithography system 10 constructed according to some embodiments. The lithography system 10, also generally referred to as a scanner, is operable to perform a lithography exposure process using appropriate radiation sources and exposure modes. In one embodiment, the lithography system 10 is an extreme ultraviolet (EUV) lithography system designed to expose a target resist layer by means of EUV light, wherein the resist layer is a suitable material sensitive to EUV light.

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

[0024] As previously described, in this embodiment, the laser beam is guided to heat the target material or droplet, thereby generating a high-temperature plasma, which further generates EUV radiation (or EUV light) 18. In one embodiment, the target material is tin (Sn). The collector reflects and focuses the EUV radiation 18 for use in a lithography exposure process, including the process discussed below with reference to System 10.

[0025] The generated EUV radiation 18 is processed by a series of optical devices, referred to as an optical device group, before reaching the target substrate. As used herein, the term "optical device" is intended to be interpreted broadly as including, but not limited to, one or more components that reflect and / or transmit and / or manipulate incident light, and includes, but is not limited to, one or more lenses, windows, filters, wedges, prisms, gratings, gradings, transmission fibers, etalons, diffusers, homogenizers, detectors and other instrument components, apertures, steering mirrors and mirrors, including multilayer mirrors, near-normal incident mirrors, grazing incident mirrors, specular reflectors, diffusers and combinations thereof. Furthermore, unless otherwise stated, the term "optical element" as used herein is not intended to be limited to components that operate only within one or more specific wavelength ranges (e.g., EUV). However, for ease of explanation, embodiments of system 10 for EUV wavelengths are discussed herein. As part of the optical device group, system 10 includes an illuminator 20. In various embodiments for EUV lithography, illuminator 20 includes reflective optics, such as a single mirror or a mirror system with multiple mirrors, to guide radiation 18 from radiation source 14 toward shield 12. Illuminator 20 may include field facet (FF) mirrors and pupil facet (PF) mirrors. Facet mirrors are optical elements used to homogenize the radiation 18 generated by EUV source 14.

[0026] After passing through the illuminator 20, radiation 18 is provided, such that its incident shield 12 exposes the surface. In this disclosure, the terms shield, light shield, and reticle are used to refer to structure 12, which provides patterning of incident radiation 18.

[0027] The lithography system 10 includes a mask holder 16 (also referred to as a stage or chuck) configured to hold, secure, and position the mask 12. In some embodiments, the mask stage 16 includes an electrostatic chuck to secure the mask 12. Thus, an electrostatic clamp can be used to secure the mask 12 to the mask stage 16. In some embodiments, the mask stage 16 includes one or more clamps for securing the mask 12. In one embodiment, the mask stage 16 includes one or more thermal regulation 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 regulation components 16A may be operatively coupled to the thermal control system 30 discussed below. The thermal regulation components 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 embodiments, the thermal regulation components 16A include a coolant. In one embodiment, the thermal regulation components 16A operate without a coolant. The thermal regulation component 16A can be used to reduce the temperature of the mask 12 and / or its surrounding environment (photomask microenvironment). This temperature reduction can maintain the mask 12 and the layers formed thereon at temperatures that reduce degassing, for example, reducing the breaking of bonds between atoms in the layers of the mask 12 due to reduced available thermal energy. In some embodiments, the mask support 16 includes a temperature sensor (e.g., a thermocouple) for providing a temperature that helps in understanding the function of the thermal regulation component. In some embodiments, the system 10 may also include other thermal regulation components, such as gas injectors or nozzles (discussed below) that provide gas in the photomask environment.

[0028] In this embodiment, the mask 12 is a reflective mask suitable for EUV lithography patterning. The mask 12 of system 10 is briefly discussed. The mask may include a substrate having a reflector (or reflective layer) disposed on the substrate, such as a multi-layer mirror (MLM). An absorption layer may be disposed on the MLM. Generally, regions of the mask where the absorption layer is present absorb incident radiation, while regions of the mask where the absorption layer is absent reflect incident radiation toward a target. The mask 12 may include a substrate of a suitable material (e.g., a low thermal expansion material (LTEM) or fused silica), on which the MLM and absorption layer are formed. In some embodiments, an EUV pellicle is positioned over the mask 12. The EUV pellicle provides a thin film that protects the EUV mask from contaminating particles or other objects that may damage the mask. The EUV pellicle is typically coupled to the EUV mask through one or more frames. In some embodiments, the EUV pellicle is not present.

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

[0030] Following the projection optics 22, the patterned radiation beam is then delivered to the target substrate 24. Similar to the optics assembly and mask discussed above, the target substrate can be provided in an exposure chamber, which is also maintained in a vacuum environment to reduce unwanted absorption of radiation 18. The exposure chamber may contain a wafer stage 26 to hold a semiconductor substrate (e.g., a wafer). In various embodiments, the target substrate 24 comprises a semiconductor wafer, such as a silicon wafer, germanium wafer, silicon-germanium wafer, III-V wafer, or other types of wafers as described above or known in the art. The target substrate 24 may be coated with a radiation-sensitive resist layer (e.g., an EUV resist layer) sensitive to the source 14. Radiation incident on the substrate 24 causes an image of the pattern defined on the mask 12, or a portion thereof, to be directed onto the semiconductor substrate, or specifically onto the resist layer (also called a photoresist layer), which is coated on the surface of the semiconductor substrate. Portions of the photoresist layer exposed to radiation undergo a chemical transformation, making them more or less sensitive to the development process.

[0031] In some embodiments, the mask 12 and the 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 a portion thereof can be in a vacuum environment to avoid EUV intensity loss. A contiguity may exist between the photoresist and the photomask, which increases the likelihood of contamination between the substrate 24 and the mask 12. The various embodiments disclosed herein can be used to reduce the contamination 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 as a mechanism for monitoring various parameters (including temperature) of the EUV lithography equipment, collecting information from various databases, analyzing the collected data and / or parameters, performing simulations, and / or actively tuning 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 tune or control a thermal conditioning component including 16A. In some embodiments, the lithography system 10 includes a gas supply module designed to supply gas to the system. In one embodiment, the gas supply module may be operatively coupled to the thermal control module 30. The gas supply module may be instructed to supply gas suitable for the thermal management of the lithography system 10.

[0033] The thermal control module 30 includes various units, sensors, modules, and components integrated and configured to perform various functions, including collecting data for the thermal control module 30. In one embodiment, 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 may be distributed in various locations, such as partially embedded and configured within the lithography system 10; or partially independent and coupled to the lithography system 10 via internet communication (e.g., internet cable connection, WiFi connection, Bluetooth connection, other suitable connection, or combinations thereof). The thermal control module 30 may 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 storage contains computer programs executed by the processor, including the analysis of the thermal control module discussed herein.

[0034] The various components, including those mentioned above, are integrated together and operable 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 or be integrated with (or coupled to) other modules.

[0035] In some embodiments, the lithography system 10 is used to fabricate integrated circuits (ICs) or portions thereof. In some embodiments, the lithography system 10 is used to form passive components including static random access memory (SRAM) and / or other logic circuitry, such as resistors, capacitors, and inductors, and active components such as p-type FETs (PFETs), n-type FETs (NFETs), FinFETs, MOSFETs, CMOS transistors, bipolar transistors, high-voltage transistors, high-frequency transistors, gate-all-around (GAA) devices, and / or other devices. This disclosure is not limited to any particular semiconductor device.

[0036] As previously described, the various aspects of this disclosure are illustrated through the performance of EUV systems and / or EUV lithography. However, the various aspects of this disclosure can also be provided in other systems and / or for performing lithography processes at other wavelengths. Thus, in some embodiments, source 14 generates radiation 18 at wavelengths such as X-rays, DUV, I-rays, G-rays, and / or other available wavelengths. Therefore, components of the optical path include elements suitable for the selected wavelength, including mirrors, lenses, liquid environments, protective mirrors, beam splitters, gratings, phase shifter components, and the like. Similarly, mask 12 is configured to appropriately pattern the provided radiation, for example, providing a phase-shifting mask, a transmission mask, and / or other suitable mask.

[0037] Referring now to Figure 2A, an exemplary mask or photomask 12 is shown in more detail. Mask 12 may be an EUV mask. In the embodiment described herein, lithography system 10 is an EUV lithography system, and mask 12 is a reflective mask for performing EUV lithography. Thus, generally, regions in mask 12 where the absorbing layer 206 is present absorb incident radiation, such as radiation 18, while regions in mask 12 where the absorbing layer is absent reflect incident radiation toward the target, thereby providing patterned radiation 18.

[0038] The mask 12 includes a substrate 200 of a suitable material, such as a low thermal expansion material (LTEM) or fused silica. Exemplary low thermal expansion materials include quartz, as well as LTM glass, silicon, silicon carbide, silicon oxide, titanium oxide, Black Diamond® (a trademark of Applied Materials), TiO2-doped SiO2, and / or other low thermal expansion materials known in the art. Above the substrate 200 are a plurality of reflective layers forming a multilayer (ML) 202. The ML 202 includes a plurality of film pairs, such as molybdenum-silicon (Mo / Si) film pairs (e.g., a molybdenum layer above or below a silicon layer in each pair of films). Alternatively, the ML may include a molybdenum-beryllium (Mo / Be) film pair, or other suitable materials that can be configured to highly reflect EUV light. The number of layers, layer thickness, and layer materials are selected based on the exposed radiation and its characteristics (e.g., wavelength and / or angle of incidence) to provide the desired reflectivity. In one embodiment, a plurality of Mo / Si pairs (e.g., 40 pairs) are formed to provide a reflective layer 202. ML 202 forms a multilayer mirror operable to reflect 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 over the capping layer 204. The absorption layer 206 is patterned according to the desired patterning of the radiation beam associated with the features to be fabricated on the target substrate. The absorption layer 206 includes a first absorption layer 206A and a covered second absorption layer (as an anti-reflective coating (ARC)) 206B. In some embodiments, the absorption layer 206 includes boron. Exemplary compositions 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 30 nm and 120 nm, such as 68 nm. In the embodiments, the thickness of the ARC layer is between 1 nm and 10 nm, for example, about 2 nm.

[0040] In some embodiments, a conductive back-side coating 208 is disposed on the opposite side of the substrate 200. The conductive back-side coating 208 can be used to attach the mask 12 to an electrostatic chuck, such as the stage 16 of the lithography system 10 described above with reference to FIG. 1. Therefore, in some embodiments, this 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 silicon (TaSi), and / or other suitable materials.

[0041] Figure 2B shows the mask 12 in an environment where a lithography process is being performed using the mask 12. An EUV radiation beam 18 is incident on the mask 12, which contains the absorption layer 206. In one embodiment, the EUV radiation beam 18 is incident on the mask 12. The radiation beam 18 has a wavelength centered at 13.5 nm. The mask 12 may be in a vacuum environment. In a further embodiment, hydrogen is available in the environment, as shown by the representative H atom in Figure 2B. In one embodiment, hydrogen radicals are generated by radiation. 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, this 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 illustrates the formation of BH3, referred to as degassing. Therefore, degassed BH3 can be present in the lithography system 10, for example, in a vacuum chamber containing the mask 12.

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

[0043] The degassed material from shield 12 and the degassed material from the photoresist on substrate 24 may mix to form undesirable compounds that contaminate system 10 and its components. In the reaction shown in FIG3, compounds degassed from shield 12 (e.g., BH 3 shown in FIG2C) and compounds degassed from substrate 24 (e.g., methylamine, ammonia) combine to form contaminants, such as methylamine-borane and / or ammonia-borane or variants thereof. In some embodiments, the compounds formed by the degassed shield 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 in the solid phase. The degassed material and its reaction products can provide contaminants that can adhere to system 10, including but not limited to cavity sidewalls, mirrors of optical paths, substrate 24, shield 12, and / or other features. In some embodiments, byproducts form solid-phase contaminants that form on the surface of shield 12, altering the reflectivity characteristics of that region of the shield, thereby creating a patterned defect that interrupts the radiation beam. For example, defects may provide unwanted absorption or reflection, thus creating defects in the pattern. When the pattern of mask 12 is repeated on substrate 24, a single defect in mask 12 can greatly affect the yield of the device formed on substrate 24 because the defect is repeatedly crossed on substrate 24.

[0044] This disclosure provides systems and methods for reducing degassing components from the mask 12, thereby reducing contamination generated in the system, in some embodiments. To reduce degassing components from the mask 12, such as reducing the generation of BH3 as discussed above, the thermal condition of the mask 12 is monitored and tuned using thermal management techniques discussed herein. For example, this disclosure recognizes that less degassing (e.g., BH3 or its derivatives) is generated at lower temperatures of the mask 12. Therefore, in some embodiments, degassing from the mask 12 generated during the lithography process is reduced by managing (lowering the temperature) the thermal conditions of the mask support 16, the mask 12 itself, and / or the environment surrounding the mask 12. Thus, thermal management in some embodiments is used to provide lower degassing by suppressing boron generation, and by reducing the amount of boron released from the absorber and / or reducing boron nitride reactions that release it into the environment. 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 by the EUV mask, thereby increasing its temperature. The thermal management of this disclosure recognizes and addresses this issue, which would otherwise lead to temperature increases.

[0045] Several studies have shown that more than half of the defects on the EUV mask in lithography systems such as System 10 discussed above originate from compounds containing boron and nitrides. Therefore, the implementation of embodiments of the present invention that reduce boron degassing can benefit the quality of the EUV lithography process by removing reactants that induce defect compounds. It should be noted that this discussion is for comprehension purposes only, and unless expressly stated in the appended claims, this disclosure is not subject to any theory or contaminant permissibility.

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

[0047] The shielding platform 16 is divided into a plurality of regions or zones 402. Zones 402 are individually tuned or configurable portions of the shielding platform 16. In embodiments, zones 402 can be individually configured to provide different thermal controls. In one embodiment, one or more thermal regulation components are provided in each zone 402. Each of the zones 402 is coupled to a thermal control module 30. In one embodiment, the thermal control module (or simply a controller) 30 provides instructions to a given zone 402 to achieve a desired temperature setpoint. Each zone 402 may include components operable to reduce the temperature of that zone—thermal regulation components 408—heat exchangers, coolants (gas or liquid), solid cooling modules, heat pipe modules, 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. A thermocouple includes an electrical device that generates a temperature-dependent voltage.

[0048] The shielding stage 16 may comprise a single zone 402 or any number of zones 402. In one 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 to a specific physical area of ​​the shield 12 held by the stage 16. The thermal control module 30 individually monitors (e.g., using feedback from sensors 408, 410) the temperature of each zone 402 and individually controls the temperature of each area by providing instructions to thermal conditioning components 408 within the stage, such as heat exchangers, coolants (gas or liquid), solid cooling modules, heat pipe modules, and thermal conditioning components other than the stage 16, such as gas injectors described below.

[0049] For this purpose, system 400 also includes one or more gas injectors (or nozzles) 404. In one embodiment, system 400 includes a plurality of gas injectors 404, each coupled to thermal control module 30. The gas injectors 404 are operable 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, gas injectors 404 provide hydrogen. Hydrogen is provided as a suitable gas due to its antioxidant, carbon-cleaning properties, and / or its high EUV transmittance. In one embodiment, gas injectors 404 deliver an airflow operable to cool one or more components of system 400. In some embodiments, gas injectors 404 provide an airflow below room temperature. In one embodiment, there are a plurality of gas injectors 404, each individually tuned or configured by thermal control module 30. In one embodiment, gas injectors 404 are individually configured to provide gas at different flow rates and / or at different temperatures. In one embodiment, the thermal control system 30 provides instructions to the gas injector 404 to guide the flow rate and / or gas temperature based on the required thermal management plan (e.g., cooling) of the shield 12.

[0050] System 400 also includes a plurality of sensors 406. Sensors 406 may be IR sensors (also known as IR cameras), UV sensors, light sensors, and / or other suitable components. Because sensors 406 do not directly contact the body being measured, they may be referred to as remote temperature sensing devices. The plurality of sensors 406 are operable to determine the temperature of one or more of the shield 12, stage 16, and / or zone 402, and / or the temperature of the environment surrounding shield 12, which is a portion of the shield environment 410 shown in the diagram. In one embodiment, sensor 406 is an infrared (IR) temperature sensor.

[0051] In one embodiment, each zone 402 has an associated remote temperature sensing device, such as an IR sensor, operable to provide a temperature associated with that zone 402. In another embodiment, each zone 402 has an associated direct temperature sensing device 410, such as a thermocouple operable to provide a temperature associated with that zone 402. In one embodiment, the number of sensors 406 and / or 410 is equal to the number of zones 402. For example, controller 30 may receive a message about temperature from a first sensor 406, and controller 30 may use this message to instruct the thermal conditioning components and / or gas injectors 404 of the first zone 402 to provide thermal cooling to the first zone. Gas injectors 404, thermal conditioning components 408 of zone 402, and sensors including remote sensors 406 and direct sensors 410 (e.g., thermocouples on stage 16) together with controller 30 provide a thermal management system. The thermal management system can be implemented in an EUV lithography system such as system 10 described in FIG. 1. In some embodiments, the thermal management system is operable to measure and configure or tune the temperature of the mask 12, thereby reducing the degassing from the mask 12 into the mask environment 410 during the lithography process.

[0052] Referring now to Figures 5, 6, 7A, 8A, and 9, embodiments of systems 500, 600, 700, 800, and 900 providing thermal management for masks or photomasks are shown, respectively. Systems 500, 600, 700, 800, and 900 are illustrative embodiments of the implementation of system 400 described with reference to Figure 4. Each of systems 500, 600, 700, 800, and 900 may include additional components and / or omit one or more components.

[0053] As shown in Figure 5, system 500 includes a shield 12, which may be substantially similar to the shield 12 discussed above. In one embodiment, a top layer of shield 12 is provided for incident radiation (i.e., the downward-facing surface in Figure 5). In one embodiment, the top layer contains boron.

[0054] In one embodiment, the mask 12 is fixed to the stage 16 by electrostatic potential. Other embodiments are also possible, including clamps that fix the mask to the stage 16.

[0055] In one embodiment, stage 16 can be moved along the X, Y, and / or Z directions by means of positioning element 502. In some embodiments, positioning element 502 includes one or more actuators that can move stage 16 a predetermined distance along a predetermined directional direction. In some embodiments, the actuators include stepper motors, piezoelectric actuators, short-stroke motors, and / or other features. In some embodiments, positioning element 502 is coupled to or includes a controller to control one or more stepper motors and / or piezoelectric actuators, causing stage 16 to have a desired movement.

[0056] Platform 16 also includes a thermal regulation component 504. The thermal regulation component 504 may include a heat exchanger, pipes or channels for providing 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 regulation component 504 contains a coolant. The coolant may be a gas or a liquid. In one embodiment, the thermal regulation component 504 operates without a coolant. In the illustrated embodiment, the thermal regulation component 504 is positioned on the side opposite the positioning element 502 to the shield 12; however, other configurations are possible. The thermal regulation component 504 may substantially resemble the thermal regulation component 16A of system 10 and / or the thermal regulation component 408 of system 400.

[0057] Thermocouple 506 is positioned on stage 16. In one embodiment, a thermistor or other temperature measuring device is used in place of thermocouple 506 or / or other components besides thermocouple 506. Thermocouple 506 is operable 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 relating to the portion of stage 16 in which it is located. In place of thermocouple 506 or in addition to thermocouple 506, temperature can be sensed by other direct sensors (e.g., thermistors) or indirect measuring components (e.g., IR cameras / sensors, UV sensors, light sensors, and / or other suitable components).

[0058] An IR module or sensor 508 is positioned adjacent to and at a distance from stage 16. The IR module 508 may be substantially similar to the sensor 406 described above with reference to FIG. 4. In one embodiment, the IR module 508 provides temperature readings for a portion of the shield 12, stage 16, and / or the surrounding environment. The IR module 508 is coupled to and provides temperature data to a thermal control module 30. Instead of or in addition to the IR module 508, temperature may be sensed by other indirect sensing components, such as a UV sensor, a light sensor, and / or other suitable components operable to remotely sense temperature.

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

[0060] System 600 of Figure 6 includes many components similar to those in system 500, such as mask 12 and mask platform 16. However, in system 600, platform 16 includes a plurality of thermal adjustment components 602. Thermal adjustment components 602 may include heat exchangers, pipes or channels for providing coolant, and / or other thermal cooling components. In an embodiment of system 600, two thermal adjustment components 602A and 602B are provided. However, as discussed above with reference to section 402, any number of thermal adjustment components may be provided. In the illustrated embodiment, thermal adjustment components 602 are positioned on the side of positioning element 502 opposite to mask 12; however, other configurations may also be used. In the illustrated embodiment, thermal adjustment component 602A is positioned over a first half (e.g., left) of mask 12, and thermal adjustment component 602B is positioned over a second half (e.g., right) of the mask.

[0061] A plurality of thermocouples 506 (506A, 506B) are positioned on the stage 16. In one embodiment, other temperature sensing devices, such as thermistors, are used instead of thermocouples 506 or / or other elements besides thermocouples 506. A first thermocouple 506A is positioned on a first portion (e.g., the left side) of the stage 16, and a second thermocouple 506B is positioned on a second portion (e.g., the right side) of the stage 16. Thermocouple 506A is operable to sense the temperature of a first region of the stage 16; thermocouple 506B is operable to sense the temperature of a second region of the stage 16. Each thermocouple 506 is coupled to a thermal control module 30 and provides the thermal control module 30 with temperature data relating to that portion (or zone) of the stage 16 on which it is located.

[0062] A plurality of IR modules 508 are positioned adjacent to stage 16. IR modules 508 may be substantially similar to the sensor 406 described above with reference to FIG. 4. In one embodiment, IR modules 508 provide temperature readings of the shield 12, portions of stage 16, and / or the surrounding environment. In one embodiment, IR module 508A provides information about a first portion of shield 12, stage 16, and / or the surrounding environment; IR module 508B provides information about a second portion of shield 12, stage 16, and / or the surrounding environment. IR modules 508A and 508B are each coupled to a thermal control module 30 and provide temperature data to the thermal control module 30.

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

[0064] The system 700 of Figure 7A is similar to the system 600 discussed in Figure 6 and also includes a shield 12 disposed on a stage 16, which may be substantially similar to those discussed above. The stage 16 also includes a plurality of thermal regulating components 602, two of which, 602A and 602B, are shown in the illustrated embodiment of system 700. In the illustrated embodiment, thermal regulating component 602A is positioned above a portion 12' of the shield 12, and thermal regulating component 602B is positioned above a portion 12'' of the shield 12. A plurality of thermocouples 506 and IR modules 508 are included in system 700. Thermocouples 506 and IR modules 508 may be substantially similar to those discussed above. Although two of the thermal regulating components 602, thermocouples 506, and IR modules 508 are shown, any number is possible.

[0065] A thermal control module or controller 30 is operatively coupled to a database 702. Database 702 includes physical structures, such as memory devices having inputs and outputs for data input and output. 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 contain pattern density information associated with mask 12. In one 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 manufacture of the layout of a wafer formed using mask 12, such as design data found in a GDS archive. In one embodiment, database 702 contains information about the pattern density of mask 12, as shown in exemplary design data 704 of FIG7B. In one embodiment, design data 704 shows a larger pattern density at region 12' than at region 12''. In another embodiment, features of design data 704 define active regions, such as fins of FinFET transistors. FIG7C shows another exemplary embodiment of design data 704' for forming mask 12. In one embodiment, design data 704' shows a larger pattern density at region 12' than at region 12''. In another embodiment, these features define contact elements of the transistor.

[0067] In an EUV mask implementation, the features of design data 704 can be defined by a patterned absorption layer. The pattern density of mask 12 can be determined by the ratio of absorbers (e.g., absorption layer 206 described above with reference to FIG. 2A) to exposed reflective ML (e.g., ML 202), the exposed reflective ML also described above with reference to FIG. 2A. In one embodiment, thermal control module 30 is operable to provide a calculated pattern density based on design data stored in database 702.

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

[0069] The thermal control module 30 may include an analysis module with various correlation analysis units that analyze the correlation 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 recognizes that the greater the pattern density of a region of the photomask, 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 commands to the thermal conditioning component 602A, the system 700 can compensate for the additional heat generated. In one embodiment, the additional cooling is used to reduce the temperature of the first portion 12', thereby reducing the generation of degassing such as BH3. It should be noted that the mask 12 is shown as comprising two regions 12' and 12''. However, any number of regions or zones is possible. In some embodiments, the number of regions determines the number of thermocouples 506, IR modules 508, and / or thermal conditioning components 602.

[0070] The system 800 of Figure 8A is substantially similar to the system 700 of Figure 7A, and similarly includes a shield 12 disposed on a stage 16 having a plurality of thermally regulating components, exemplified by thermal regulating components 602A and 602B. In the illustrated embodiment, thermal regulating component 602A is positioned above a portion 12' of the shield 12, and thermal regulating component 602B is positioned above a portion 12'' of the shield 12. A plurality of thermocouples 506 and IR modules 508 are included in the system 800 and can be substantially similar to those discussed above. Furthermore, although two thermocouples 506 and IR modules 508 are shown, any number is possible.

[0071] Thermal control module 30 is operatively coupled to database 702, which is substantially similar to that discussed above with reference to FIG. 7. In one embodiment, as previously described, database 702 contains design data indicating the density of the photomask pattern. Thermal control module 30 is also operatively coupled to database 80. Database 802 contains physical structures, such as memory devices having inputs and outputs for data inflow and outflow. 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 may be separate from or integrated with database 702.

[0072] Database 802 may contain lithography parameters, such as information about the lithography process and / or the masking used in the lithography process. In one embodiment, database 802 contains information about exposure parameters to be implemented by system 800. In one embodiment, database 802 contains the exposure time of the area of ​​mask 12. In some embodiments, database 802 contains scanner parameters, such as step conditions (e.g., timing) and scan time in the x or y axis direction. In an embodiment, database 802 contains EUV pulse conditions, such as pulse width (e.g., w nanoseconds), pulse repetition or frequency (e.g., f kHz), power (e.g., p W / cm²), and / or energy (mJ) / cm³. Database 802 may include and / or thermal control module 30 for calculating energy (E=Pavg / R) and / or power (e.g., Ppeak=Pavg / R*tau, where R is the repetition rate (e.g., 50 kHz) and tau is the pulse duration of the EUV lithography process (e.g., 150 nm). In one embodiment, database 802 contains the number of EUV pulses required to melt the droplet (e.g., Sn) and its impact on the system's temperature profile. In another embodiment, database 802 contains temperature profiles indicating the highest temperature during associated scan conditions (as discussed below).

[0073] Based on information received from thermocouple 506, IR module 508, database 702, and database 802, thermal control module 30 calculates instructions and sends them to each of thermal regulation components 602A and 602B operably coupled thereto, to control the components in a desired manner to regulate the temperature of the first portion 12' and the second portion 12'' of the mask 12 during exposure. Different instructions can be sent to each of the thermal regulation components 602A and 602B. As previously described, in one embodiment, thermal control module 30 receives information from database 702 that the mask portion 12' has a first pattern density (see Figures 7B and 7C) and the mask portion 12'' has a second pattern density (see Figures 7B and 7C), the second pattern density being less than the first pattern density. Cooling requirements (e.g., a larger pattern density requires greater cooling) can be determined by the analysis module using the pattern density.

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

[0075] In one embodiment, the thermal control module 30 receives temperature profile data from a database 802 and / or the analysis module of the thermal control module 30 can use the data from the database 802 to generate temperature profile data (e.g., through simulation). The temperature profile data shows the thermal condition of a mask or a portion thereof over time when a mask or similar structure is exposed to a lithography process defined by parameters stored in the database 802. In one embodiment, the thermal control module 30 receives previously obtained data from the database 802 (e.g., via system 800) showing temperature readings that change over time when a mask 12 or similar structure is exposed. In an embodiment, the thermal control module 30 includes an analysis module operable to generate a temperature profile that includes the temperature changing over time when the mask 12 is exposed. An exemplary temperature profile data 804 is shown in Figure 8B. The analysis module of the thermal control module 30 can use the temperature profile data 804 to determine the cooling requirements for a given time during the 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 EUV scanning of the shield 12, and a second cooling performance during a second duration following the first duration of EUV scanning of the shield 12.

[0076] Therefore, in system 800, the thermal control module 30 may include an analysis module containing various correlation analysis units that analyze the correlation between various parameters, such as the correlation between pattern density and heat generation, and apply this to analytical data associated with the temperature profile of the mask 12 (e.g., collected through simulation, experimental results, previous product runs, similar masks, or the like). In some embodiments, the analysis module of the thermal control module 30 recognizes that the greater the pattern density of a region of the mask, the greater the heat generated during the EUV process. In other words, exposure of mask portion 12' generates more heat than exposure of mask portion 12''. By providing additional cooling commands to the thermal regulation component 602A, the system can compensate for the additional heat generated. In some embodiments, the analysis module of the thermal control module 30 identifies a higher temperature for the mask 12 during a specific time period during the EUV process. By providing additional cooling commands to the thermal regulation component 602A, the system can compensate for the additional heat generated during the appropriate time. In one embodiment, cooling, directed by the thermal control module 30, is used to reduce the temperature of the shielding portion 12, thereby reducing the generation of degassing such as BH 3.

[0077] The system 900 of Figure 9 is similar to the system 800 of Figure 8, including a shield 12 disposed on a platform 16, which includes heat-regulating components 602A and 602B. In the illustrated embodiment, heat-regulating component 602A is positioned above a portion 12' of the shield 12, and heat-regulating component 602B is positioned above a portion 12'' of the shield 12. However, similarly, the shield 12 can be divided into any number of portions or zones.

[0078] A plurality of thermocouples 506 and IR modules 508 are included in system 900. Thermocouples 506 and IR modules 508 may be substantially similar to those discussed above. Although there are two thermocouples 506 and IR modules 508, any number is possible. Thermal control module 30 is operatively coupled to libraries 702 and 802, library 702 being substantially similar to those discussed above with reference to Figures 7A, 7B, and 7C, and library 802 being substantially similar to those discussed above with reference to Figures 8A and 8B. In an embodiment, as previously stated, library 702 contains design data indicating the density of the mask pattern. In one embodiment, as previously stated, library 802 contains temperature profile data indicating the expected temperature profile when scanning mask 12 using system 900. In embodiments of system 900, one or more of these components may be omitted.

[0079] System 900 further illustrates a first airflow 902 and a second airflow 904. In one embodiment, the first airflow 902 is provided by a first gas injector 902A, and the second airflow 904 is provided by a second gas injector 902B. The gas injectors may be substantially similar to the gas injector 404 discussed above with reference to FIG. 4. The first airflow 902 is provided at a first distance from the shield 12. The second airflow 904 is provided at a second distance from the shield 12, which may be greater than the first distance. In one embodiment, one or more of the airflows 902 and 904 comprise laminar flow in the x-direction. Airflows 902 and 904 may both be the same gas (e.g., hydrogen), but this is not necessary. The flow rate of airflow 902 may differ from that of airflow 904.

[0080] Furthermore, the temperature of gas flow 902 can differ from that of gas flow 904. For example, in one embodiment, gas flow 902 can be approximately 2°C to approximately 20°C cooler than gas flow 904. In one embodiment, both gas flow 902 and gas flow 904 are below ambient temperature (e.g., below approximately 22°C). In another embodiment, gas flow 902 and / or gas flow 904 are above approximately 0°C. In one embodiment, gas flow 904 is approximately room temperature (e.g., approximately 22°C), and the temperature of gas flow 904 is lower than that of gas flow 904, for example, at least 3°C ​​lower. In one embodiment, gas flows 902 and 904 are provided at temperatures at which condensation does not occur. In some embodiments, the photomask chuck pressure is such that condensation does not occur at the reduced temperatures of the provided gas flows 902 and 904. In another embodiment, the gas flow comprises a gas having a phase transition triple point provided at approximately 1 kPa and 0°C. The gas temperature can be maintained such that the gas flow remains in the gas phase.

[0081] Airflows 902 and 904, as well as gas injectors 902A and 902B, are controlled by a thermal control module 30. In one embodiment, the thermal control module 30 provides commands related to the flow rate and / or temperature of airflow 902. The thermal control module 30 uses the commands related to the flow rate and / or temperature of airflow 902 provided by the thermal control module 30. The thermal control module 30 uses information provided from databases 702 and / or 802, thermocouple 506, and IR module 508 to determine commands for airflows 902 and 904. The thermal control module 30 can determine that the desired cooling of the shield 12 is achieved by the combination of airflows 902, 904, and thermal conditioning component 602.

[0082] Therefore, in system 900, thermal control module 30 may include an analysis module providing various correlation analysis units that analyze the correlation between various parameters, such as the correlation between pattern density and heat generation, and apply this to the analysis of data from previous temperature profiles associated with the scanning conditions of mask 12 (e.g., collected through simulation, experimental results, previous product runs, similar masks, or the like). In some embodiments, the analysis module of thermal control module 30 recognizes that the greater the pattern density of a region of the mask, the greater the heat generated during the EUV process. In other words, the exposure of mask portion 12' generates more heat than the exposure of mask portion 12''. The system can compensate for the additional heat generated by providing additional cooling commands to thermal conditioning unit 602 and / or gas injectors 902A and 902B that respectively provide airflow 902 and 904. In some embodiments, the analysis module of thermal control module 30 identifies a greater amount of heat generated in mask 12 during a specific time period during the EUV process. By providing additional cooling commands to the thermal conditioning unit 602 and / or the gas injectors 902A and 902B that respectively provide airflow 902 and 904, the system can compensate for additional heat generated over a suitable period of time. In one embodiment, cooling instructed by the controller 30 is used to reduce the temperature of the shielding portion 12, thereby reducing the generation of degassing such as BH 3.

[0083] Figure 10 shows an embodiment of the lithography tool 1000, simplified for ease of understanding. In this embodiment, the lithography tool 1000 is an EUV lithography tool. The lithography tool 1000 can be substantially similar to the system 10 described above with reference to Figure 1. Additional components can be added to the lithography tool 1000, and components can 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 the main chamber 1002 of the tool 1000. Within the microenvironment 1004, there is an illuminator component 1008 and a projection optics (or POB) component 1010. The illuminator component 1008 may include a field plane and a pupil plane, and in some embodiments may be substantially similar to the illuminator 20 discussed above with reference to FIG. 1. The projection optics (or POB) component 1010 may include a plurality of mirrors, and in some embodiments may be substantially similar to the projection optics 22 discussed above with reference to FIG. 1.

[0085] Microenvironment 1004 defines and includes an optical assembly or path for radiation 18. Component 1003 defining the microenvironment may include components for correction, guidance, modification, and / or inclusion of radiation 18. Environment 1004 may be a vacuum environment.

[0086] A plurality of gas nozzles are disposed in tool 1000. A first gas injector 1012 (also referred to as a y-nozzle) is disposed adjacent to the bottom of shield 12. In some embodiments, gas injector 1012 is contained in or between light shield (REMA) blades (not shown). Airflow 1012A is provided from nozzle 1012. Airflow 1012A may be substantially similar to the airflow from injector 404 in system 400 of FIG. 4 and / or airflow 1012A may be substantially similar to the airflow 904 described above with reference to FIG. 9. Exemplary gases of airflow 1012A provided from gas injector 1012 include, but are not limited to, H, He, Ar, N and / or combinations thereof. As previously stated, in one embodiment, airflow 1012A may be below room temperature.

[0087] Gas injector 1014 is positioned at a distance greater than the bottom of shield 12. Gas injector 1014 may be adjacent to or embedded in component 1003 defining the microenvironment. Airflow 1014A is provided from injector 1014. Exemplary gases provided from gas injector 1014 include, but are not limited to, H, He, Ar, N, and / or combinations thereof. In one embodiment, airflow 1014A is similar to the airflow from injector 404 in system 400 of FIG. 4 and / or the aforementioned airflow 904 described with reference to FIG. 9. As previously mentioned, in one embodiment, 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 at least 3°C ​​below room temperature but above the temperature of airflow 1012A. In one embodiment, airflow 1014A is provided in a channel of component 1003 and released into microenvironment 1004, in which 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 shield 12 is positioned such that the radiation beam is incident on its surface; the shield 12 is held by a shield stage 16. In some embodiments, the shield stage 16 includes thermal conditioning components and / or thermal sensors, such as those discussed above.

[0089] The portion of Figure 10 adjacent to the mask 12 can be referred to as the photomask microenvironment. The photomask microenvironment includes the mask or photomask 12 and the mask stage or chuck 16, as well as thermal conditioning components, such as those discussed above with respect to Figures 5, 6, 7A, 8A, and 9. For example, the thermal conditioning components may provide cooling for one of the multiple areas of the stage 16 and the mask 12.

[0090] The photomask microenvironment also includes components for correction, guidance, modification, and / or containing radiation 18, such as photomask shielding blades (REMA blades). In some embodiments, a gas nozzle, such as a first gas nozzle 1012, is positioned within the REMA blade.

[0091] Referring now to Figure 11, a method 1100 for providing a thermal control plan is shown. The thermal control plan provided by method 1100 can be provided to and / or implemented by a lithography tool such as the lithography system 10 of Figure 1. One or more steps of method 1100 can be performed by a thermal control module 30, also known as a controller, as discussed above with reference to Figure 1.

[0092] Method 1100 includes an operation 1202 of receiving pattern density information. In an embodiment, the pattern density is collected from a design file associated with the photomask. The design file may be provided in GDS file format. In an embodiment, the pattern density information may be depicted by regions or areas of the photomask. Exemplary embodiments of pattern density information are described above with reference to Figures 7B and 7C.

[0093] Method 1100 includes operation 1204, wherein lithography parameters containing mask usage information are received. Exemplary parameters include parameters such as equivalent power, exposure time, step conditions, scan time, pulse frequency and width, ambient temperature, mask edge temperature, step duration, and / or other lithography parameters and / or their surrounding environment that affect the thermal conditions of the mask. In one embodiment, an equivalent power of 235 W / cm² is provided. In an embodiment, the provided mask edge temperature is set to approximately 24°C. In an embodiment, a step duration set to approximately 60-75 milliseconds is provided. In an embodiment, the lithography parameters also include sensor data from sensors located 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] Method 1100 includes operation 1206, in which lithography parameters and pattern density information are used to simulate the lithography process to determine a thermal profile. The analysis module includes various correlation analysis units that analyze the correlations between various parameters, such as the correlation between pattern density and thermal conditions of the photomask and / or its surrounding environment during exposure, the correlation between lithography parameters and thermal conditions of the photomask during exposure, and other correlations. An example of the resulting thermal profile is illustrated above with reference to Figure 8B. This simulation can display one or more peak temperatures during the simulated lithography process (see Figure 8B). In an embodiment, the maximum temperature is between approximately 280°C and 350°C after the first scan and between 380°C and 450°C after the second scan, and field stepping positioning can occur between the first and second scans. In an embodiment, the simulation can provide cooling during field stepping. In one embodiment, cooling of approximately 150°C and 300°C is provided. In an embodiment, cooling of approximately 25% to 75% of the temperature rise provided by the previous scan is provided during field stepping. The analysis of the thermal profile can be performed by a controller such as the thermal control module 30.

[0095] The analysis in operation 1206 may also include establishing a correlation between the resulting thermal profile and the degassing of the composition (e.g., a B derivative, such as BH3). In embodiments, the analytical module utilizes simulations, experimental data, and / or chemical reaction analysis to determine, for example, the degassing level generated from an absorber layer defining a pattern density for a given thermal profile. In embodiments, the analytical module recognizes that higher thermal profile temperatures provide greater degassing.

[0096] Method 1200 includes operation 1208 of determining thermal management measures. The analysis module can develop thermal management measures or measures to reduce the temperature of the photomask and / or its surrounding environment during the lithography process. In one embodiment, the thermal management measures include setting one or more thermal conditioning components positioned in and / or away from the photomask (e.g., gas injectors). In embodiments, the thermal management measures are instructions sent to the thermal conditioning components, which can be substantially similar to those discussed above with reference to thermal conditioning component 408 of FIG. 4 or thermal conditioning components 504, 602 of FIG. 5 to 9. For example, in some embodiments, the thermal conditioning components include heat exchangers, pipes or channels for providing coolant, solid cooling modules, heat pipe modules and / or other thermal management components and / or other thermal cooling components on the photomask stage or chuck. In one embodiment, the thermal management measures are instructions sent to the thermal conditioning components of one or more gas injectors, including setting the airflow temperature and / or flow rate from the gas injectors. The gas ejector can be substantially similar to those discussed above in reference to airflows 902, 904 and / or gas ejectors 1012, 1014. Thermal management measures may include instructions for adjusting the thermal conditioning components during a given lithography process. For example, a thermal control plan may reduce the gas ejection temperature during the scanning process and / or provide additional cooling in the thermal conditioning components of the masking stage during the lithography process.

[0097] In one embodiment, instead of directly sending instructions, method 1100 inputs the determined thermal management measures into the simulation of operation 1206 to determine the thermal profile during the iterative operation process.

[0098] Method 1100 includes operation 1210, wherein thermal control planning instructions are implemented during the lithography process. This implementation may include setting, adjusting, or tuning the thermal conditioning components and / or gas injectors of the masking stage before and during the lithography process.

[0099] It should be noted that method 1100 of FIG11 provides a thermal control plan prior to performing the lithography process in some embodiments. In some embodiments, the thermal control plan is formulated during the lithography process. In embodiments, 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 the aforementioned thermocouples 506A, 506B, and / or remote sensors such as the aforementioned IR modules or sensors 508A, 508B. Real-time data can be used to determine the thermal control plan, as discussed in operation 1210. In some embodiments, method 1100 is performed on each zone of the photomask.

[0100] Figure 12 shows a flowchart of method 1300 for performing a lithography process. Method 1300 can be implemented by the lithography system 10 described above with reference to Figure 1 and / or other systems and tools disclosed herein.

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

[0102] Method 1300 includes operation 1304 of loading a target substrate, such as a semiconductor wafer, into a lithography system. A photoresist layer is coated on the target substrate. In an embodiment, the photoresist layer is sensitive to EUV radiation.

[0103] Method 1300 includes 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 aforementioned thermal control module 30. Providing the thermal control plan includes receiving information about the temperature of the photomask, lithography parameters (including mask usage), and various components. The thermal control plan uses this information to implement a thermal management plan, which includes thermal management measures that instruct thermal conditioning components to reduce the temperature of the photomask or one or more components of the lithography system. In some embodiments, the thermal control plan determines thermal management measures that send instructions to thermal conditioning components such as heat exchangers in a mask holder. In some embodiments, the thermal control plan determines thermal management measures that send instructions to thermal conditioning components of one or more gas injectors of the lithography system. Therefore, implementation of the thermal control plan includes adjusting one or more components (e.g., heat exchangers, gas injectors).

[0104] In one embodiment, the thermal control plan is provided by, for example, the operation shown in method 1100 described above with reference to FIG11. In one embodiment, the thermal control plan is updated during the lithography process based on received feedback (e.g., from a temperature sensor). In other words, operation 1306 can occur multiple times during the execution of operation 1308. The thermal control plan can be determined, tuned, and implemented for the entire photomask. In other embodiments, the thermal control plan can be determined, tuned, and implemented for individual zones of the photomask.

[0105] Figure 12 illustrates an embodiment of a plurality of steps that may be included in operation 1306 to form a thermal control plan. In step 1306A, data on the lithography system, such as photomask usage, is collected. This data may be substantially similar to the data described above in database 802 as shown in Figure 9. In step 1306B, data on the mask pattern is collected. In this embodiment, the data includes pattern density. This data may be substantially similar to the data described above in database 802 as shown in Figure 8 and / or database 802 as shown in Figures 7B and 7C. In step 1306C, thermal information is collected. The thermal information may include temperature received 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 a mask support, such as a thermocouple directly positioned on the mask support. The thermal information may include temperature received from a second temperature sensing device (e.g., a remote temperature sensing device, such as an IR sensor). The second received temperature may be associated with a photomask, such as from a remote temperature sensing device pointing towards the photomask. In some embodiments, temperature readings are received from each of the plurality of bands of the light source. In step 1306D, a thermal control plan is formulated. The thermal control plan may be substantially similar to that discussed above and includes instructions for thermal regulation components, such as components in the shielding support (e.g., heat exchangers, coolant) and / or gas injectors (e.g., delivering cooling gas). One or more of steps 1306A, 1306B, 1306C, and 1306D may be omitted.

[0106] Method 1300 includes operation 1308 of performing a lithography exposure process on a wafer in a lithography system. In one embodiment, operation 1308 is an EUV lithography operation, and the laser and solder droplet generator 68 are synchronized via a suitable mechanism (e.g., control circuitry with a timer for control and synchronization) (specifically, laser pulses and solder droplet generation are synchronized). The synchronized laser excites the target material droplets and generates plasma, thereby producing EUV radiation. During operation 1308, the generated EUV radiation is irradiated onto a photomask (by means of an illuminator such as illuminator 20) and further projected onto a photoresist layer coated on the wafer (by means of a POB such as optics 22), thus forming a latent image on the photoresist layer. In one embodiment, the lithography exposure process is performed in a scanning mode.

[0107] Specifically, during the lithography exposure process, various instructions for the thermal management plan established in operation 1306 can be implemented simultaneously with or overlapping with the lithography exposure process. For example, method 1300 can continue to collect data at operation 1306 via temperature sensors (e.g., temperature readings via thermocouples, IR sensors, or the like) and analyze the collected data via an analysis module to execute and / or adjust the thermal control plan during the exposure of the mask. For example, in one embodiment, temperature is received from sensors on the mask holder during the lithography process (e.g., during the exposure of the mask to EUV).

[0108] In an embodiment, the thermal control management of method 1300 is used to reduce the temperature of the photomask and / or its surrounding environment. The temperature reduction can decrease degassing from the photomask layers, such as atoms from the absorber layer (e.g., B). In one embodiment, boron degassing is reduced due to the thermal control management. In some embodiments, the reduction in boron degassing reduces the available reactants in the system that could form contaminating compounds, including those discussed in Figure 3 above.

[0109] Method 1300 may include other operations to complete the photolithography patterning process. For example, method 1300 may include operation 1310, forming a photoresist pattern on a substrate having a plurality of openings defined thereon by developing an exposed photoresist layer. In one embodiment, the photoresist layer is positive; the exposed portions of the photoresist layer are removed by a developer. In another embodiment, the photoresist layer is negative; the exposed portions of the photoresist layer are retained; and the unexposed portions are 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, which involves performing a manufacturing process on a wafer through openings in the 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] Therefore, this disclosure provides an exemplary lithography system and method for performing lithography with a thermal control module, which performs thermal control management by providing thermal management measures or instructions to thermally modulated components such as gas injectors and / or mask stage features (e.g., heat exchangers or coolant pipes / channels). In some embodiments, thermal control management takes into account pattern density differences on the mask. In some embodiments, thermal control management takes into account mask usage, such as scan / step time. Thermal control management can be used to sufficiently reduce the temperature of the mask and / or its surrounding environment to reduce degassing of material from the mask (e.g., absorber layer). Reduction of degassing can reduce the mask defect rate by reducing contaminants in the system.

[0112] In one example embodiment, this disclosure provides a method for extreme ultraviolet (EUV) lithography. The method includes collecting thermal data associated with a photomask during the lithography process. The thermal data is used to determine thermal management measures, wherein the thermal management measures include providing instructions to thermal conditioning components to cool the photomask.

[0113] In a further embodiment, the method includes receiving design data associated with a pattern on a photomask and using the design data to determine thermal management measures. In embodiments, the method includes receiving temperature readings from a thermocouple and receiving temperature readings from an IR sensor. In some embodiments, the thermal management measures include instructing a thermal regulation component of a first gas injector to provide an airflow. In one embodiment, the airflow is below about 22°C. In some embodiments, the thermal management measures provided by this method include instructing a thermal regulation component of a second gas injector to provide another airflow. The airflow from the first gas injector may be at least 3°C ​​cooler than the airflow from the second gas injector. In an embodiment, the thermal management measures instruct a thermal regulation component of a heat exchanger in a photomask chuck used in the lithography process. This method may include instructing the heat exchanger such that instructions are provided to a first component having coolant in a first portion of the photomask chuck, and to a second component having coolant in a second portion of the photomask chuck. The first and second components are independently controllable.

[0114] In another example, a method for performing lithography is implemented. 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 by the mask. The method continues by 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 a temperature associated with the mask. The output of a thermal conditioning component is modified based on the received temperature.

[0115] In a further embodiment, modifying the output of the thermal regulation component includes providing an airflow with a temperature below 22°C. In some embodiments, modifying the output of the thermal regulation component further includes providing coolant to the shield support. In one embodiment, the method includes receiving a first temperature associated with a first region of the shield support and a second temperature associated with a second region of the shield support. The temperatures can be received from an IR sensor. In some embodiments, performing thermal control management further includes receiving the pattern density of the shield and determining an initial output of the thermal regulation component based on the pattern density.

[0116] In another example, this disclosure provides an extreme ultraviolet (EUV) lithography system. The system includes a photomask holder, a temperature sensor, a first thermal regulation component, a second thermal regulation component, and a control module. The first thermal regulation component is operable to reduce the temperature of the photomask within the photomask holder. The second thermal regulation component is operable to provide airflow near the photomask within the photomask holder. The control module is coupled to the temperature sensor, the first thermal regulation component, and the second thermal regulation component.

[0117] In one embodiment, the temperature sensor includes a first thermocouple on a first region of the photomask holder and a second thermocouple on a second region of the photomask holder. In one embodiment, the temperature sensor further includes at least one remote temperature sensing device. In an embodiment, the at least one remote temperature sensing device includes a first IR sensor for sensing the temperature of the first region of the photomask in the photomask holder and a second IR sensor for sensing the temperature of the second region of the photomask in the photomask holder. In one embodiment, the system further includes another temperature regulating component adjacent to the first thermal regulating component, wherein the other thermal regulating component is operable to cool the first region of the photomask in the photomask holder, and the first thermal regulating component is operable to cool the second region of the photomask in the photomask holder.

[0118] The foregoing has outlined the features of several embodiments to enable those skilled in the art to better understand the various aspects of this disclosure. Those skilled in the art should understand that they can readily use this disclosure as a basis for designing or modifying other processes and structures to achieve the same purposes and / or advantages as the embodiments described herein. Those skilled in the art should also recognize that such equivalent constructions do not depart from the spirit and scope of this disclosure, and that they can make various changes, substitutions, and alterations without departing from the spirit and scope of this disclosure.

[0119] 10: Microfilm System / System 12: Mask / Structure / Light Mask / Mask Section 12': Part / Area / First Part / Mask Part 12'': Part / Area / Second Part / Mask Part 14: EUV source / source / radiation source 16: Masking bracket / masking table / table / chuck 16A: Thermal regulation component 18: EUV radiation / radiation / EUV radiation beam / radiation beam 20:Illuminator 22: Projection Optical Components Box / Projection Optical Components / Optical Components 24: Target substrate / substrate 26: Substrate Stage / Wafer Stage 30: Thermal control system / thermal control module / controller 200:Substrate 202: Multilayer / ML / Reflective Layer 204: Capping layer 206: Absorption Layer 206A: First Absorbing Layer / Absorbing Layer 206B: Second Absorbing Layer 208: Conductive back-side coating / coating 400: System 402: Zone / First Zone 404: Gas ejector / ejector 406: Sensor / First Sensor / Remote Sensor 408: Thermal regulation components / sensors 410: Temperature sensor / sensor / shielded environment / direct temperature sensing device / direct sensor 500: System 502: Positioning element 504: Thermal regulation components 506: Thermocouple 506A: Thermocouple / First Thermocouple 506B: Thermocouple / Second Thermocouple 508: IR Module / Sensor 508A: IR Module / Sensor 508B: IR Module / Sensor 600: System 602: Thermal regulation component 602A: Thermal regulation component 602B: Thermal regulation component 700: System 702: Database 704: Design Data 704': Design Data 802: Database 804: Temperature profile data 902: First airflow / airflow 902A: First gas ejector / gas ejector 902B: Second Gas Injector / Gas Injector 904: Second airflow / airflow 1000: Microfilm Tools / Tools 1002: Master Room 1003: Components 1004: Microenvironment / Environment 1008: Lighting components 1010: Projection optical components 1012: First gas injector / gas injector / nozzle / first gas nozzle 1012A: Airflow 1014: Gas ejector / ejector 1014A: Airflow 1100: Method 1202: Operation 1204: Operation 1206: Operation 1208: Operation 1210: Operation 1300: Method 1302: Operation 1304: Operation 1306: Operation 1306A: Steps 1306B: Steps 1306C: Steps 1306D: Steps 1308: Operation 1310: Operation 1312: Operation

Claims

1. An extreme ultraviolet (EUV) lithography method, the method comprising: collecting thermal data associated with a photomask during a lithography process; receiving design data associated with a pattern on the photomask; and using the thermal data and the design data to determine a thermal management measure, wherein the thermal management measure comprises providing an instruction to a thermal conditioning component to cool the photomask.

2. The method as described in claim 1, wherein the design data includes a pattern density.

3. The method of claim 1, wherein the collection of thermal data comprises: receiving a temperature reading from a thermocouple; and receiving a temperature reading from an infrared (IR) sensor.

4. The method as described in claim 1, wherein the thermal management measure provides instructions to the thermal regulation component of a first gas injector to provide an airflow.

5. A method of performing lithography, the method comprising: 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 is reflected by 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 comprises: receiving a temperature associated with the mask holder; receiving a temperature associated with the mask; modifying an output of a thermal conditioning component based on the received temperature, wherein modifying the output comprises determining an airflow; wherein performing the thermal control management further comprises: receiving a pattern density of the mask; and determining an initial output of the thermal conditioning component based on the pattern density.

6. The method of claim 5, wherein modifying the output of the thermal regulation component includes determining that the temperature of the airflow is below 22°C.

7. The method of claim 5, wherein receiving the temperature associated with the shield bracket includes receiving a first temperature associated with a first region of the shield bracket and a second temperature associated with a second region of the shield bracket.

8. An extreme ultraviolet (EUV) lithography system, comprising: a photomask support; a temperature sensor; a first thermal regulation component in the photomask support, wherein the first thermal regulation component is operable to reduce a temperature of a photomask in the photomask support; a second thermal regulation component spaced apart from the photomask support, wherein the second thermal regulation component is operable to provide an airflow adjacent to a photomask in the photomask support; and a control module coupled to the temperature sensor, the first thermal regulation component, and the second thermal regulation component; wherein the control module determines an initial output of the first thermal regulation component and / or the second thermal regulation component based on a pattern density of the photomask.

9. The EUV lithography system as claimed in claim 8, wherein the temperature sensor comprises a first thermocouple on a first region of the photomask support and a second thermocouple on a second region of the photomask support.

10. The EUV lithography system of claim 8 further includes another temperature regulating component adjacent to the first thermal regulating component, wherein the other thermal regulating component is operable to cool a first region of a photomask in the photomask holder, and the first thermal regulating component is operable to cool a second region of the photomask in the photomask holder.

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