Particle testing system, sampling strip, projection exposure apparatus and method for testing surface particle contamination

Abstract

The invention relates to a particle testing system (1) for testing particle contamination on a surface (2), comprising a sampling tape (7) for receiving particles (5) and a sampling device (3). The sampling device (3) comprises a roller body (9) which is arranged to guide the sampling tape (7) on an outer surface (10) of the roller body. The sampling device (3) is designed to roll the roller body (9) together with the sampling tape (7) over the surface (2) to be tested in order to transfer particles (5) from the surface (2) to be tested to the sampling tape (7). The sampling device (3) has a guide frame (22) in order to position the sampling device (3) on or adjacent to the surface (2) to be checked. The guide frame (22) has at least one contact interface (24, 25) by which the guide frame (22) rests on the surface (2) to be checked or on another surface. According to the invention, the sampling device (3) has a first measuring device (16) and / or a second measuring device (19). The first measuring device (16) is designed to detect any rotational movement of the roller body (9). The second measuring device (19) is designed to detect any contact pressure of the roller body (9) on the surface (2) to be checked.

Description

[0001] This application claims priority to German Patent Application No. 10 2020 201 935.5, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0002] This invention relates to a particle inspection system for inspecting surface contamination, comprising a sampling strip and a sampling device for picking up particles.

[0003] The present invention also relates to a projection exposure apparatus for semiconductor lithography.

[0004] The present invention also relates to sampling strips for a particle inspection system for inspecting particle contamination on surfaces.

[0005] The present invention also relates to the use of sampling strips, methods for inspecting particle contamination on surfaces, and computer program products having program coding devices for implementing the method of inspecting particle contamination. Background Technology

[0006] Particle analysis for detecting particulate contamination on surfaces can be used in meaningful ways across almost every field of natural science and technology. Particles deposited on the surface to be inspected can be qualitatively and / or quantitatively determined during the entire particle inspection process or through sampling. Particles are typically different types of small objects, such as worn metal, worn plastic, dust, or organic matter—depending on the specific technological application and environment.

[0007] Surface particle contamination needs to be checked frequently, especially during the process of ensuring the technical cleanliness of technical components. This check should ensure that surface particle contamination (e.g., due to the manufacture, maintenance, and / or operation of technical components) is sufficiently low so that the function of the technical equipment is not limited in the short or long term.

[0008] Especially for components of projection lithography (PTC) equipment, such as the surfaces of optical or mechanical parts, ensuring low particle contamination is now of paramount importance. As semiconductor circuits continue to miniaturize, the demands on the resolution and accuracy of PTC equipment are correspondingly increasing. Correspondingly high requirements are also placed on the components used there, which particularly affect the beam path within the PTC equipment. Specifically, due to resolution requirements, the positioning of optical components (such as mirrors in EUV (“Extreme Ultraviolet”) PTC equipment) is now extremely demanding. Due to the high precision required for optical and mechanical components, particle contamination during the manufacturing, maintenance, and operation of PTC equipment must also be considered.

[0009] Various methods are known in practice for inspecting particulate contamination on surfaces. For example, it is known that particulate contamination on surfaces can be detected using a compressed air probe combined with an optical particle counter. However, such methods do not provide reliable options for determining the size of small particles, and therefore are often inaccurate in providing reliable statements about size distribution and particle type.

[0010] It is also known that particle samples can be collected from a surface using sampling strips or adhesive pads (e.g., using so-called particle measurement cards, PMCs), and then optically evaluated using incident or grazing light. However, this does not yield sufficiently meaningful conclusions about size distribution and particle type, as analytical detection using incident or grazing light can lead to a covering effect on the particles, resulting in distortion of the measurement results.

[0011] Furthermore, the problem is that known processes are highly user-dependent, which often leads to low reproducibility in sampling and evaluation, for example, due to manual contact operation of sampling strips with uncertain contact pressure.

[0012] Therefore, known methods for sampling surfaces to detect particle contamination are associated with high inaccuracies. In particular, there is a need to improve known methods to meet the high requirements of particle inspection of components in projection exposure equipment. Summary of the Invention

[0013] In view of the prior art, the object of the present invention is to provide an improved particle inspection system, in particular, which can ensure a reduced tendency to errors when inspecting particle contamination on surfaces.

[0014] Another object of the present invention is to provide an improved projection exposure apparatus for semiconductor lithography, which has a particle inspection system to advantageously inspect the particle contamination of the components of the projection exposure apparatus, particularly in the case of reducing error tendency.

[0015] Finally, another object of the present invention is to provide an improved sampling strip for inspecting particle contamination on surfaces. Another object of the present invention is to provide a method for utilizing the sampling strip.

[0016] Another object of the present invention is to provide an improved method for inspecting particle contamination on surfaces, wherein in particular the tendency to produce errors is reduced. Finally, another object of the present invention is to provide an advantageous computer program product.

[0017] Regarding the particle inspection system, this objective is achieved by the features detailed in claim 1. Regarding the projection exposure apparatus, this objective is achieved by the features of claim 13. Regarding the sampling strip, this objective is achieved by the features of claim 14, and regarding the use of the sampling strip, this objective is achieved by claim 15. Regarding the method for inspecting particle contamination on a surface, this objective is ultimately achieved by claim 16, and regarding the computer program product, this objective is achieved by claim 17.

[0018] The dependent claims and features described below relate to advantageous embodiments and variations of the invention.

[0019] A particle inspection system is provided for inspecting particle contamination on a surface to be inspected. The system has a sampling strip and a sampling device for picking up particles.

[0020] In the context of this invention, particles can be considered to include metallic particles, non-metallic particles, fibers (especially polymer fibers), fragments of foil (metallic foil, non-metallic foil, or composite foil), dust particles, and / or organic particles. In the context of this invention, it is advantageous to sample and inspect particles or fibers, particularly those composed of metal shavings, resin, plastic, or dust.

[0021] In the context of this invention, the surface to be inspected can be considered part of the claimed particle inspection system. However, the surface to be inspected can also be independent of the particle inspection system.

[0022] The sampling strip is preferably made of a strip of material, the width of which is much greater than its thickness.

[0023] Preferably, the sampling strip is formed of plastic, such as polymer film, paper, metal (e.g., metal foil) and / or fabric.

[0024] According to the invention, the sampling device has a roller configured to (at least partially) guide the sampling strip on its outer surface.

[0025] The present invention is described below using a single roller as an example. However, in principle, the sampling device may also have more than one roller with the same or different constructions, such as two rollers, three rollers, four rollers, or even more rollers.

[0026] In addition, multiple sampling bars with the same or different structures can be provided, such as two sampling bars, three sampling bars, four sampling bars, or even more sampling bars.

[0027] It is even possible to optionally provide multiple sampling devices with the same or different constructions, such as two sampling devices, three sampling devices, four sampling devices, or even more sampling devices.

[0028] The sampling strip can be partially or completely wrapped around the roller. The sampling strip can run around the roller in exactly one turn, less than one turn, or more than one turn (e.g., two, three, four, five, or more turns).

[0029] According to the invention, the sampling strip is configured such that the roller body rolls against the surface to be inspected together with the sampling strip in order to transfer particles (or particle samples) from the surface to be inspected to the sampling strip.

[0030] A roller body can be installed so that it can rotate about the rotation center axis in the sampling device.

[0031] By placing the roller (along with the sampling strip) on the surface to be inspected, the roller can roll on the surface to be inspected with a defined contact pressure and a subsequent translational motion of the axis of rotation, preferably parallel to the surface to be inspected, so that the particles will gradually transfer from the surface to the sampling strip.

[0032] The sampling strip can remain on the roller during its rolling and is correspondingly fixed to the roller by force-fit, form-fit, and / or adhesive means (preferably reversibly fixed). However, the sampling strip may also detach from the roller while the roller is rolling against the surface to be inspected and thus initially remain on the surface to be inspected. The sampling strip can therefore be fully or partially unfolded from the roller. However, preferably, the sampling strip remains on the roller when the roller is guided or rolls against the surface to be inspected.

[0033] According to the present invention, the sampling device has a first measuring device and / or a second measuring device. The first measuring device is designed to detect any rotational movement of the roller. The second measuring device is designed to detect any contact pressure of the roller on the surface to be inspected.

[0034] The sampling device preferably has a first measuring device and a second measuring device. However, the sampling device may also exclusively have either a first measuring device or a second measuring device. In principle, the sampling device may also have additional measuring devices to allow for further measurements from those mentioned measurements or other measurements.

[0035] Preferably, a sampling device is provided for measurement, while the roller and sampling strip roll together against the surface to be inspected. Measurements can be performed at discrete time intervals or continuously. The measuring device, especially a second measuring device for detecting contact pressure, can, if appropriate, perform measurements even when the roller is stationary.

[0036] Sampling of surfaces can be improved by using a sampling device with a first measuring device and / or a second measuring device, because the user of the sampling device can be guided by the detected measurements and can continuously adjust the rotational motion and / or contact pressure to defined specifications. The measuring device can, in particular, sample defined rolling distances or defined surface areas during sampling. Defined contact angles and release angles relative to the surface to be inspected can also be achieved. Due to the measuring device, the contact pressure and rolling speed during the rolling of the roller against the surface to be inspected can be advantageously reproduced and monitored.

[0037] In an advantageous development of the invention, the sampling strip may have a sampling surface designed to adhesively extract particles from the surface to be inspected. Preferably, the sampling surface faces away from the outer surface of the roller as the sampling strip is guided along the outer surface of the roller.

[0038] In principle, the sampling strip could also have two sampling surfaces on opposite sides. However, preferably, the sampling strip has exactly one sampling surface.

[0039] The surface of the sampling strip opposite the sampling surface can preferably be designed to be bonded to the outer surface of the roller, preferably in a reversible manner, so that the user of the particle inspection system can remove the sampling strip from the roller without damage after sampling the surface, or so that the sampling strip has detached from the roller during surface sampling.

[0040] In one development of the invention, the sampling surface may have a pressure-sensitive adhesive for adhering and extracting particles from the surface to be inspected.

[0041] The pressure-sensitive adhesive used can be preferably optimized because, on the one hand, all particles of the expected type and size adhere to the sampling surface, meaning they can be extracted from the surface to be inspected, and on the other hand, the sampling surface with the pressure-sensitive adhesive can still be removed without leaving any residue on the surface.

[0042] Even without pressure-sensitive adhesives, favorable adhesive properties of the sampling surface can be provided. For example, the material of the sampling surface (or the entire sampling strip) can be designed to allow particles to penetrate into the sampling surface or sampling strip and adhere to the sampling strip, for example, due to microscale interlocking. In principle, any desired adhesive mechanism can be provided to enable particle adsorption onto the sampling strip.

[0043] In one development of the invention, the sampling strip may be formed of a translucent material. Preferably, the sampling strip is transparent.

[0044] The sampling strip can be translucent or transparent, especially orthogonal to the sampling surface. Preferably, the translucency allows particles absorbed on the sampling surface to be visible from the side of the sampling strip opposite to the sampling surface.

[0045] Therefore, particle inspection systems can be provided advantageously for monitoring surface contamination using transparent sampling strips, such as transparent adhesive strips. Sampling strips made of translucent materials, combined with transmission light microscopy, may be particularly advantageous.

[0046] In contrast, existing sampling strips are typically made of opaque materials, so the evaluation of particles captured by the sampling strip is usually performed using grazing light (i.e., using a light source arranged laterally relative to the sampling surface) or incident light. Therefore, the discernibility of particles on the typically darker surface of the sampling strip may be insufficient. Overlay effects can also make accurate determination of particle size difficult or impossible. Since the sampling strip in this context is made of a translucent material, transmitted light can be used to evaluate the particles appearing on the sampling strip. This reduces the tendency for errors, especially in determining particle size.

[0047] In one development of the invention, the roller may be elastically mounted relative to the surface to be inspected in the sampling device, preferably spring-mounted. Preferably, the roller is mounted in the sampling device by means of one or more elastic elements.

[0048] Because the rollers in the sampling device are mounted by one or more elastic elements, it is advantageous to establish a defined contact pressure of the rollers on the surface to be inspected. This can be achieved, for example, by means of the weight of the sampling device or rollers acting on the elastic element or spring, the separation of the sampling device from the surface to be inspected, and / or the adjustability of the elasticity of the elastic element (or some other effect on the elastic element).

[0049] The contact pressure can be advantageously optimized for different surfaces to be sampled or inspected. For example, the contact pressure on a metal surface (e.g., stainless steel) can be designed to be higher than that on a plastic surface.

[0050] The optimal contact pressure for a given surface type can be determined through simulation or a series of tests to maximize the amount of particles absorbed by the sampling strip.

[0051] Preferably, the roller is connected to the frame assembly of the sampling device via one or more, such as two, three, four or even more, elastic elements, such as springs (including linear springs, such as helical springs or compression springs) or elastic polymers.

[0052] In one development of the invention, the first measuring device may have an optical sensor or a magnetic sensor to detect the rotation angle of the roller, the rotation speed of the roller, and / or the angular velocity of the roller.

[0053] The first measuring device can be designed to detect any dynamic movement of the roller.

[0054] For example, the optical sensor of the first measuring device can be designed to detect one or more optical markers along the circumference of the roller to determine the angular change of the roller, which can then be used to detect the rotational speed and / or angular velocity of the roller.

[0055] Alternatively or additionally, the first measuring device may also have a magnetic sensor, such as one or more reed sensors.

[0056] In principle, the first measuring device may alternatively or additionally include other types of sensors for detecting the dynamic or rolling motion of the roller against the surface to be inspected. The use of optical and / or magnetic sensors is mentioned only as an example.

[0057] In an advantageous development of the invention, the second measuring device may have a force sensor, preferably a force sensor with a spring element, an electrodynamic sensor, or a piezoelectric sensor, to detect the contact pressure of the roller on the surface to be inspected.

[0058] For example, the force sensor or some other sensor in the second measuring device can be designed to detect the extension or deflection of the linear spring or elastic polymer that elastically connects the roller to the frame assembly of the sampling device. By comparing with a reference element, the contact pressure can then be inferred from the deflection of the spring or elastic polymer.

[0059] If the roller is elastically connected to the frame assembly of the sampling device at multiple points, for example by using multiple springs or multiple elastic polymers, then alternatively, multiple second measuring devices or multiple force sensors of a common second measuring device may also be provided to jointly detect the contact pressure of the roller.

[0060] The technical implementation principle described above for forming the force sensor should be considered merely illustrative. In principle, the second measuring device can be designed in any desired manner to detect the contact pressure of the roller on the surface to be inspected.

[0061] In one development of the invention, the sampling device may have a display, particularly an electronic display, to show the user of the sampling device information detected by a first measuring device and / or by a second measuring device.

[0062] The display can therefore advantageously show the user whether the contact pressure and rotational movement of the rollers meet the specifications. Based on the displayed data, the user can thus optimize the contact pressure and / or rotational movement of the rollers, such as the roller speed.

[0063] The rotational motion of the rollers, such as the angular velocity of the rollers rolling against the surface, can be optimized to maximize the amount of particles absorbed by the sampling strip and / or minimize the sampling time.

[0064] As an alternative to or supplement to the use of a display, the sampling device may also have an actuation or mechanical device to limit the contact pressure and / or speed or rotational speed of the roller (preferably but not necessarily based on information detected by means of a first measuring device and / or by means of a second measuring device).

[0065] According to the invention, the sampling device has a guide frame for positioning the sampling device on or next to a surface to be inspected. The guide frame has at least one positioning interface through which the guide frame rests on the surface to be inspected or on another surface (next to the surface to be inspected).

[0066] The guide frame may have one, two, three, four, or even more branches to position the sampling device on or beside the surface to be inspected. More preferably, the guide frame has four branches or four positioning points.

[0067] By using a guide frame, the distance between the sampling device and the surface to be inspected can be defined, thus also defining the distance between the roller and the surface and the contact pressure of the roller. In this way, the contact pressure is particularly likely to be separated from the user, resulting in highly reproducible sampling results.

[0068] Alternatively, the distance between the sampling device or roller and the surface to be inspected can be adjusted by means of a guide frame, such as by using an adjusting screw or a telescopic slider.

[0069] In an advantageous development of the invention, the guide frame may move parallel to or next to the surface to be inspected, so that the roller rolls against the surface to be inspected together with the sampling strip.

[0070] For example, the guide frame may have rollers or wheels to ensure particularly low friction and gentle mobility against or beside the surface to be inspected.

[0071] The rollers or wheels of the guide frame (or some other positioning interface where the guide frame rests against the surface to be inspected or some other surface) may preferably be made of plastic or rubber in order to mechanically soften the surface to be inspected and to leave the lowest level of residue or particles on the surface.

[0072] In an advantageous development of the invention, the sampling device may have an actuator to move the roller parallel to the surface to be inspected, so as to automatically roll the roller and the sampling strip onto the surface to be inspected.

[0073] Preferably, a linear actuator device or linear actuator can be provided. For example, the roller can be movable via a translation unit guided in the track of the sampling device, for example using a cable engaged with the translation unit.

[0074] In one development of the invention, the particle inspection system may have an evaluation device designed to evaluate particles sampled by a sampling strip by means of particle size, particle type, particle quantity and / or particle distribution.

[0075] The evaluation results related to particles can optionally be combined with measurements taken by the evaluation device based on sampling, such as information related to the contact pressure used, the size of the surface portion being examined, and / or the rotational speed of the roller.

[0076] Automated evaluation is preferably performed using control devices, especially image evaluation software.

[0077] The evaluation device can be partially or completely integrated into the sampling device. However, it is preferable that the evaluation device is formed separately from the sampling device. This can advantageously reduce the weight and size of the sampling device.

[0078] The sampling strip can be removed from the roller and / or the surface to be inspected by the user of the particle inspection system after sampling or after particle aspiration, and sent to the evaluation unit for evaluation. For easier removal of the sampling strip, the entire roller can also optionally be removed from the sampling device.

[0079] The evaluation device can be configured to display the evaluation results to the user, for example, using a monitor or printed output. The evaluation device can also be additionally or alternatively configured to record the evaluation results, for example, by recording them on a data storage device and optionally linking them to an identifier for the surface or object / part being inspected.

[0080] In one development of the present invention, the evaluation device may include a light microscope, preferably a transmission light microscope.

[0081] Therefore, the sampling strip can be advantageously examined under a microscope. Transmitted light microscopy is particularly preferred, especially when the sampling strip is translucent. However, alternatively, it is conceivable to use grazing light or incident light for (optical) examination, preferably microscopic examination, especially when the sampling strip is opaque.

[0082] The present invention also relates to a projection exposure apparatus for semiconductor lithography, wherein a particle inspection system (in particular—but not exclusively—according to the details above and below) is provided for inspecting particle contamination on the surface of components of the projection exposure apparatus.

[0083] Projection exposure equipment or its components / parts can advantageously be used to test cleanliness based on particle inspection systems, especially during the manufacturing process.

[0084] The surface of the optical element of the optical unit in the projection exposure apparatus can preferably be inspected. The optical element can be, in particular, a lens or a mirror.

[0085] However, in principle, any component of the projection exposure equipment can be inspected, such as even purely mechanical parts, components of the projection exposure equipment's light source, or the wafer of the projection exposure equipment.

[0086] The inspection of particulate contamination is particularly advantageous for components assembled with other components or mounted on other components during the assembly of projection exposure equipment, or components surrounded by housing components.

[0087] Particle inspection can advantageously be performed during the manufacturing and assembly of the projection exposure equipment, for example, before the parts to be sampled / inspected are assembled. However, particle inspection can also be performed periodically during equipment operation, such as during maintenance intervals, to ensure long-term proper operation of the projection exposure equipment.

[0088] This invention is particularly applicable to microlithography DUV (“deep ultraviolet”) projection exposure equipment, and especially to microlithography EUV projection exposure equipment. Possible uses of this invention also relate to immersion lithography. However, particle sampling in the projection exposure equipment described herein is merely an illustrative application of the invention.

[0089] The present invention also relates to a sampling strip of a particle inspection system for inspecting particle contamination on a surface, having a sampling surface designed to adhesively extract particles from the surface to be inspected, wherein the sampling strip is formed of a translucent material.

[0090] The sampling strip can be designed to be mounted on the outer surface of the roller.

[0091] In one configuration of the sampling strip, the sampling surface may have a pressure-sensitive adhesive for adhering and extracting particles from the surface to be inspected.

[0092] The sampling strip could be sufficiently elastic in a direction orthogonal to the sampling surface to absorb all types and sizes of the desired particles. The deformability or elasticity of the sampling strip can be chosen such that, under the desired contact pressure, the particles can be pressed deep enough into the sampling surface so that the sampling surface can provide sufficient holding force for the particles.

[0093] The thickness of the sampling strip, i.e., its range from the sampling surface to the opposite side of the sampling surface, can be, for example, 0.50 mm to 5.00 mm, preferably 0.75 mm to 3.00 mm, and more preferably 1.00 mm to 2.00 mm. In principle, the thickness can be less than 0.50 mm or greater than 5.00 mm.

[0094] The sampling strip of the present invention is particularly advantageous for inspecting surface particle contamination caused by components of a projection exposure system used for semiconductor lithography.

[0095] The present invention also relates to the use of the sampling strips detailed above and below in the process of evaluating particles sampled by the sampling strips using a transmission light microscope.

[0096] Sampling strips can be advantageously used to monitor contamination or to examine particles, in which case a particular combination of translucent sampling strips and a transmission light microscope can provide especially accurate and repeatable results.

[0097] The results of the sampling can ultimately be used to determine the cleanliness of the sampled surface or component in terms of technical cleanliness when particle contamination exceeds a defined threshold.

[0098] The present invention also relates to a method for inspecting particle contamination on a surface, wherein a roller of a sampling device and a sampling strip guided above the outer surface of the roller are rolled against the surface to be inspected in order to transfer particles from the surface to be inspected onto the sampling strip.

[0099] A first measuring device is provided, which includes the rotational movement of a roller. As an alternative to or supplement to the first measuring device, a second measuring device is provided, which detects the contact pressure of the roller on the surface to be inspected.

[0100] The method of the present invention can advantageously improve the reproducibility and accuracy of particle inspection, especially when sampling particles from the surface to be inspected, because it can at least reduce user dependence.

[0101] The contact operation can be performed with analysis and / or actuation assistance or in a fully automated manner. The rolling of the roller against the surface to be inspected can be assisted by analysis and / or by actuators, or it can be fully automated.

[0102] In an advantageous configuration of the method, the sampling strip may be guided on the outer surface such that the sampling surface of the sampling strip, which is designed to pick up particles from the surface to be inspected, is away from the outer surface of the roller.

[0103] In an advantageous configuration of this method, the sampling surface may also be provided with a pressure-sensitive adhesive for the adhesion and adsorption of particles.

[0104] In one configuration of this method, the sampling strip can also be formed of a translucent material.

[0105] In an advantageous configuration of this method, the roller may be elastically mounted relative to the surface to be inspected in the sampling device, preferably spring-mounted.

[0106] In an advantageous configuration of this method, it may be possible to display to the user of the sampling device the information detected by the first measuring device and / or the information detected by the second measuring device.

[0107] According to the present invention, in the context of this method, the sampling device is positioned on or next to the surface to be inspected via a guide frame. The guide frame has at least one positioning interface through which the guide frame rests on the surface to be inspected or another surface.

[0108] In one configuration of the method, the guide frame can be moved parallel to or adjacent to the surface to be inspected, so that the roller rolls against the surface to be inspected together with the sampling strip.

[0109] In an advantageous configuration of this method, the roller may be moved parallel to the surface to be inspected by an actuator device, so that the roller rolls against the surface to be inspected in an automated manner along with the sampling strip.

[0110] In one configuration of this method, the particles drawn by the sampling strip can be evaluated by particle size, particle type, particle quantity, and / or particle distribution.

[0111] In one configuration of this method, the evaluation may be performed by microscopic examination, preferably using transmitted light.

[0112] Finally, the present invention also relates to a computer program product having a program encoding means so as to implement the method according to the details above and below when the program is executed on the control device of the particle inspection system (in particular—but not exclusively—the control device of the particle inspection system according to the details above and below).

[0113] The control device may be in the form of a microprocessor. Instead of a microprocessor, any other device may be provided for implementing the control device, such as an arrangement of one or more discrete electrical components on a printed circuit board, a programmable logic controller (PLC), an application-specific integrated circuit (ASIC), or any other programmable circuit, such as a field-programmable gate array (FPGA), a programmable logic array (PLA), and / or a commercial computer.

[0114] The features already described in connection with the particle inspection system of the present invention can, of course, also be advantageously implemented in the projection exposure apparatus of the present invention, the sampling strip of the present invention, the usage of the present invention, the method of the present invention, and the computer program product of the present invention, and vice versa. Furthermore, the advantages already mentioned in connection with the particle inspection system of the present invention can also be considered relevant to the projection exposure apparatus of the present invention, the sampling strip of the present invention, the usage of the present invention, the method of the present invention, and the computer program product of the present invention, and vice versa.

[0115] Furthermore, it should be noted that terms such as “comprising,” “having,” or “with” do not exclude other features or steps. Additionally, terms such as “a” or “the” that indicate a single step or feature do not exclude multiple features or steps, and vice versa.

[0116] However, in pure embodiments of the invention, the use of the terms "comprising," "having," or "with" to introduce features may also be exhaustive. Therefore, an enumeration of one or more features can be considered exhaustive within the scope of the invention, for example, when each claim is considered individually. As an example, the invention may consist solely of the features specified in claim 1.

[0117] It should be noted that labels such as “first” or “second” are primarily used to distinguish the features of individual devices or methods, and are not necessarily intended to indicate that the features need to be related to each other.

[0118] It should be further emphasized that the values ​​and parameters described in the context also include deviations or variations from the respective specified values ​​or parameters, which are ±10% or less, preferably ±5% or less, more preferably ±1% or less, and very particularly preferably ±0.1% or less, provided that such deviations are not excluded in the practice of implementing the invention. The specification of the ranges of starting and ending values ​​also covers all values ​​and fractions included by the respective specified ranges, particularly the starting and ending values ​​and the corresponding mean.

[0119] The working examples of the invention are explained in more detail below with reference to the accompanying drawings.

[0120] The accompanying drawings illustrate preferred examples of operation in various cases, wherein the individual features of the invention are described in combination with each other. Features of the examples of operation can also be implemented independently of other features of the same examples of operation, and therefore those skilled in the art may readily combine them with features of other examples of operation to form further feasible combinations and sub-combinations. Attached Figure Description

[0121] In the accompanying drawings, the same reference numerals are used for elements that have the same function.

[0122] The attached diagram is shown in schematic form:

[0123] Figure 1 EUV projection exposure equipment;

[0124] Figure 2 DUV projection exposure equipment;

[0125] Figure 3 Projection exposure equipment used for immersion lithography;

[0126] Figure 4 The particle inspection system of the present invention includes a sampling device, a sampling strip, and an evaluation device;

[0127] Figure 5 With enlarged detail illustrations Figure 4 The sampling device in the middle;

[0128] Figure 6 A second working example of a sampling device having a guide frame that can move parallel to the surface to be inspected;

[0129] Figure 7 A third example of a sampling device with an actuator for automated movement of a roller parallel to the surface to be inspected;

[0130] Figure 8 A fourth working example of a sampling device with an evaluation device integrated into the sampling device; and

[0131] Figure 9 The rolling motion of the rollers and sampling strips is shown in a magnified detail illustration. Detailed Implementation

[0132] Figure 1 As an example, a basic setup of an EUV projection exposure apparatus 400 for semiconductor lithography, in which the present invention can be used, is shown. The illumination system 401 of the projection exposure apparatus 400 includes: a radiation source 402 and an optical unit 403 for illuminating a matter field 404 in a matter plane 405. A mask master 406 arranged in the matter field 404 is illuminated, and the mask master is held by a mask master holder 407, schematically illustrated. A projection optical unit 408, schematically illustrated only, is used to image the matter field 404 onto an image field 409 in an image plane 410. The structure on the mask master 406 is imaged onto a photosensitive layer of a wafer 411 arranged in the region of the image field 409 in the image plane 410, and the wafer is held by a wafer holder 412, also partially illustrated.

[0133] Radiation source 402 can emit EUV radiation 413, specifically in the range of 5 nanometers to 30 nanometers. The radiation path of the EUV radiation 413 is controlled using optically distinct and mechanically adjustable optical elements 415, 416, 418, 419, and 420. Figure 1In the case of the EUV projection exposure apparatus 400 illustrated, the optical element is in the form of an adjustable mirror as in a suitable embodiment, which is mentioned below only as an example.

[0134] EUV radiation 413 generated by radiation source 402 is aligned by a concentrator integrated in light source 402, allowing EUV radiation 413 to pass through the central focal point in the region of the intermediate focal plane 414, and then reach field plane mirror 415. Downstream of field plane mirror 415, EUV radiation 413 is reflected by pupil plane mirror 416. By means of pupil plane mirror 416 and optical assembly 417 having mirrors 418, 419, 420, the field plane of field plane mirror 415 is imaged into object field 404.

[0135] Figure 2 An illustrative DUV projection exposure apparatus 100 is shown. The projection exposure apparatus 100 includes an illumination system 103, means for receiving and precisely positioning a mask master stage 104 (which determines the subsequent structure on the wafer 102), a wafer holder 106 for holding, moving and precisely positioning the wafer 102, and an imaging means specifically having a projection lens 107 having a plurality of optical elements 108 held in the lens housing 140 of the projection lens 107 by means of a mounting member 109.

[0136] Optical element 108 can be designed as a separate refractive, diffractive, and / or reflective optical element 108, such as a lens element, a mirror, a prism, a termination plate, etc.

[0137] Based on the basic functional principle of the projection exposure device 100, the structure introduced into the mask master 105 is imaged onto the wafer 102.

[0138] The illumination system 103 provides a projection beam 111 in the form of electromagnetic radiation, which is required to image the mask master 105 onto the wafer 102. The source for this radiation can be a laser, a plasma source, or the like. The radiation is shaped in the illumination system 103 by optical elements so that the projection beam 111 has desired properties regarding diameter, polarization, wavefront shape, etc., when incident on the mask master 105.

[0139] The image of the mask master 105 is generated by the projection beam 111 and transferred from the projection lens 107 to the wafer 102 in a suitably reduced form. In this case, the mask master 105 and the wafer 102 can move synchronously, such that the area of ​​the mask master 105 is imaged onto the corresponding area of ​​the wafer 102 substantially continuously during the so-called scanning operation.

[0140] Figure 3In an embodiment of a DUV projection exposure apparatus for immersion lithography, a third projection exposure apparatus 200 is illustrated by way of example. For other background information relating to such a projection exposure apparatus 200, see, for example, WO2005 / 069055A2, the contents of which are incorporated herein by reference. Therefore, the exact functions will not be discussed in detail here.

[0141] In accordance with Figure 2 In a manner comparable to the DUV projection exposure apparatus 100, the mask stage 104 is identifiable, and the subsequent structure on the wafer holder 106 or the wafer 102 disposed on the wafer stage is determined by the mask stage. For this purpose, Figure 3 The projection exposure device 200 also has multiple optical elements, particularly lens element 108 and reflector 201.

[0142] The use of this invention is not limited to projection exposure devices 100, 200, and 400, and is particularly not limited to projection exposure devices 100, 200, and 400 having the aforementioned configuration. The analytical arrangement and analytical method of this invention are, in principle, applicable to determining the alignment or position and / or orientation of any optical element.

[0143] The following figures are for illustrative purposes only and illustrate the invention in a highly schematic manner.

[0144] Figure 4 A particle inspection system 1 of the present invention for inspecting particle contamination on a surface 2 is shown. In principle, the particle inspection system 1 can be used to inspect particle contamination on any surface 2 of any component. However, it is particularly advantageous to perform particle inspection on the surface 2 of components of a projection exposure apparatus (e.g., components of one of the projection exposure apparatuses 100, 200, 400 described above). Most preferably, the particle inspection system 1 can be used to inspect the surface 2 of optical elements, such as the surface 2 of one of the optical elements 415, 416, 418, 419, 420, 108, 201 of the optical systems 107, 403, 408 of the projection exposure apparatuses 100, 200, 400. In particular, the particle inspection system 1 can alternatively be applied to inspecting particle contamination on the surface 2 of mechanical components / mechanical parts of a projection exposure apparatus (e.g., one of the projection exposure apparatuses 100, 200, 400 described above). The invention is also applicable, of course, to inspecting particle contamination on the surface 2 of a projection exposure apparatus having a different design than the described projection exposure apparatus.

[0145] In principle, this invention is applicable to inspecting particle contamination on any surface 2, which must meet the particle cleanliness standard.

[0146] The particle inspection system 1 has a sampling device 3 for sampling the surface 2 to be inspected. Figure 5 Show Figure 4 An enlarged illustration of the sampling device.

[0147] The particle inspection system 1 also includes an evaluation device 4, which is designed to evaluate the particle size, particle type, particle quantity, and / or particle distribution by the sampling device 3 (see [reference]). Figure 9 The particle 5 is sampled. A control device 6 can be provided to monitor and / or evaluate and / or control the particle inspection (sampling and / or evaluation). In particular, a computer program product with a program coding device can be provided to run a method for inspecting particle contamination on the surface 2 to be inspected when the program is executed on the control device 6 of the particle inspection system 1.

[0148] The particle inspection system 1 also has a sampling strip 7 for picking up particles 5 from the surface 2 to be inspected. The sampling strip 7 can be specifically designed for the adhesive pickup of particles 5 and for this purpose can, for example, have a sampling surface 8.

[0149] The sampling device 3 may have a roller 9, which is configured to run the sampling strip 7 along its circumference on its outer surface 10 (see...). Figure 9 In particular, the sampling surface 8 of the roller 9, which is away from the outer surface 10. The sampling strip 3 can be configured such that the roller 9 and the sampling strip 7 roll against the surface 2 to be inspected, so as to transfer the particles 5 from the surface 2 to be inspected to the sampling strip 7.

[0150] The sampling device 3 has a gripping element 11 for the user of the particle inspection system 1. The gripping element 11 is connected to the frame assembly 12. However, in principle, the gripping element 11 can be omitted.

[0151] Roller body 9 is mounted around the axis of rotation A (see...) Figure 9 The roller 9 in the sampling device 3 is rotatable and elastically connected to the frame assembly 12 via a frame 13. Because the roller 9 in the sampling device 3 is elastically mounted relative to the surface 2 to be inspected, the contact pressure of the roller 9 on the surface 2 to be inspected can be advantageously analytically defined and / or detected. For this purpose, the frame 13 can be connected to the frame assembly 12 via one or more elastic elements 14, such as spring elements or elastic polymers. In the working example, a linear spring for forming the elastic element 14 is shown as an example.

[0152] The sampling device 3 can be moved by the user with the desired contact pressure over the surface 2 along with the roller 9 and as parallel as possible to the surface 2 to be inspected. As a result, the roller 9 rolls against the surface 2 to be inspected together with the sampling strip 7, and picks up the particles 5 on its sampling surface 8. The sampling surface 8 may have a pressure-sensitive adhesive 15 (see...). Figure 9), used for the adhesive adsorption of particles 5. In principle, any desired adhesive mechanism can be implemented to enable the adsorption of particles 5 on the sampling surface 8; the use of adhesive or pressure-sensitive adhesive 15 is considered only as an example.

[0153] Figure 9 The enlarged detail illustration shows the rolling motion of roller 9 against the surface 2 to be inspected. As an example, Figure 9 The sampling strip 7 shown has the sampling surface 8 mentioned in the case of the pressure-sensitive adhesive 15 used for the adhesive absorption of particles 5, and is formed of a translucent material.

[0154] like Figure 9 As shown, the sampling strip 7 can be fixed to the outer surface 10 of the roller body 9 such that it detaches from the roller body 9 and remains on the surface 2 when it rolls against the surface 2. Alternatively (preferably), however, the sampling strip 7 remains on the outer surface 10 during the rolling motion of the roller body 9 and only draws particles 5 from the surface 2 when the roller body 9 moves above the surface 2.

[0155] Sampling device 3 may have a first measuring device 16 (see example) Figure 5 The first measuring device 16 is designed to detect any rotational movement of the roller 9. As an example, the first measuring device 16 in the working example has an optical sensor 17 to detect the rotation angle, rotational speed, and / or angular velocity of the roller 9 using optical markers 18 on the roller 9. In the working example, a single marker 18 is shown on the roller 9; in principle, any number of markers 18 can be provided to detect the rotation angle or any change in rotation angle with maximum continuity. As an alternative to the optical sensor 17, a magnetic sensor (e.g., a reed sensor) or other sensors may also be provided. Multiple first measuring devices 16 may also be provided, each having at least one sensor.

[0156] As an alternative to or addition to the first measuring device 16, the sampling device 3 may have a second measuring device 19, which is designed to detect any contact pressure of the roller 9 on the surface 2 to be inspected. For this purpose, the second measuring device 19 may, for example, have a force sensor 20, preferably a force sensor with a spring element, an electrodynamic sensor, or a piezoelectric sensor. In particular, multiple second measuring devices 19 may also be provided, each having one or more sensors or force sensors 20. For example, the number of second measuring devices 19 may correspond to the number of elastic suspension points on the frame 13 of the frame assembly 12, as shown in the working example. However, in principle, the measurement of contact pressure may also be performed at only a single suspension point or a single elastic element 14.

[0157] Measuring devices 16, 19 and their sensors 17, 20 can be mounted on, for example, rack 13 or frame assembly 12. Measuring devices 16, 19 and sensors 17, 20 are shown only schematically in the working example and are shown as black boxes in each case.

[0158] Information detected by the first measuring device 16 and / or by the second measuring device 19 can be provided to the user of the sampling device 3. For this purpose, for example, the electronic display 21 shown can be provided. Using the detected data related to rotational movement and / or contact pressure, the user is positioned to optimize the contact pressure and / or rotational movement and maintain a constant contact pressure and / or rotational movement. In this way, the sampling results can be more reproducible and thus improved.

[0159] Figure 6 A second operational example of the sampling device 3 of the present invention is shown. To further improve the sampling results and, in particular, to further separate it from the user of the particle inspection system 1, the sampling device 3 may have a guide frame 22 for positioning the sampling device 3 on or beside the surface 2 to be inspected. With the guide frame 22, the distance between the frame assembly 12 and the surface 2 to be inspected can be defined, thereby defining the contact pressure of the roller 9. For example, the contact pressure can be defined by modifying the distance D between the frame assembly 12 and the surface 2 to be inspected, or by adjusting the length of individual branches of the guide frame 22. For this purpose, the branches of the guide frame 22 may be adjustable in length, for example, telescopically adjustable, or—as shown—having adjusting screws 23. Alternatively, the contact pressure can be adjusted in another manner, for example, by modifying the elastic element 14 (e.g., via an increase in spring tension).

[0160] The guide frame 22 can move parallel to or on the surface 2 to be inspected, so that the roller 9 rolls against the surface 2 together with the sampling strip 7. For this purpose, Figure 6 In the working example, the guide box 22 has corresponding suitable wheels 24 to ensure minimal frictional resistance and thus ensure smooth movement.

[0161] Figure 6 The sampling device 3 in the second working example is capable of completely separating the contact pressure from the user during sampling on surface 2. In this way, it is particularly possible to ensure a constant and defined predefined contact pressure throughout the sampling process.

[0162] With Figure 7 The third working example of the sampling device shown can further improve the sampling process. Figure 7 The guide frame 22 shown does not have wheels 24, but has a simple positioning interface 25.

[0163] For the sake of simplification, Figure 7 In the middle (and in the following) Figure 8 The guide box 22 (in the middle) is shown in a form that cannot be adjusted in length. However, Figure 7 and 8 The guide frame 22 of the sampling device 3 shown in the working example can also be length-adjustable and has, for example, the adjustment screw 23 described above.

[0164] The actuator device 26 of the sampling device 3 is configured to move the roller 9 parallel to the surface 2 to be inspected, so that the roller 9, together with the sampling strip 7, rolls against the surface 2 to be inspected in an automated manner. The rotational movement of the roller 9 is therefore no longer performed by the user and is thus also separated from the user, which can again improve the sampling results. The actuator device 26 may have a guide rail system, in which case the frame assembly 12 includes one or more rails 27 to move the roller 9 linearly with its frame 13. The roller 9 may be guided in the rails 27 or by means of a translation unit 28.

[0165] For evaluation, the user can remove the sampling strip 7 from the roller 9 and / or surface 2 and feed it to the evaluation device 4 (see [link]). Figure 4 The entire roller 9 can optionally be removed from the sampling device 3. The evaluation device 4 may in particular have a microscope 29, preferably a light microscope. The control device 6 can be configured to automatically evaluate the image information detected by the microscope 29 or the evaluation device 4.

[0166] In a particularly preferred variant, the sampling strip 7 can be formed of a translucent material. Therefore, a transmitted light microscope is well-suited for evaluating the sampled particles 5, whereby the light source 30 of the microscope 29 fully illuminates the sampling strip 7 from the opposite side of the sampling surface 8. For example, the transmitted light microscope can avoid the occlusion effect that occurs under grazing light conditions.

[0167] Figure 8 A fourth working example of the invention is shown, wherein the evaluation device 4 has been integrated into the sampling device 3. For illustrative purposes, in Figure 8 Measuring devices 16 and 19 were omitted.

[0168] exist Figure 8 In this device, both the roller body 9 and the sampling strip 7 are made of a translucent material. A light source 30 disposed within the roller body 9 generates transmitted light even during sampling, so that the particles 5 absorbed on the sampling strip 7 can be evaluated by a microscope 29 while sampling is still in progress. The microscope 29 moves along the frame assembly 12 of the sampling device 3 together with the frame 1 of the roller body 9.

[0169] In this way, the process of removing the sampling strip 7 from the sampling device 3 can be separated from the user or omitted, and the sampling process can be accelerated.

[0170] The sampling and rotational movement of the roller 9 can be matched with or synchronized with the evaluation device 4 to provide sufficient time for the evaluation device 4 to evaluate the sample or particle 5. For example, the rotational movement of the roller 9 can also be cyclical, in which case the roller 9 stops during the evaluation cycle and then moves forward.

Claims

1. A particle inspection system (1) for inspecting particle contamination on a surface (2), comprising a sampling strip (7) for absorbing particles (5) and a sampling device (3), wherein the sampling device (3) has a roller (9) configured to guide the sampling strip (7) on its outer surface (10), and wherein the sampling device (3) is configured to roll the roller (9) together with the sampling strip (7) against the surface (2) to be inspected, so as to transfer particles (5) from the surface (2) to be inspected to the sampling strip (7), wherein, The sampling device (3) has a guide frame (22) for positioning the sampling device (3) on or beside the surface (2) to be inspected, wherein the guide frame (22) has at least one positioning interface (24, 25) through which the guide frame (22) is located on the surface (2) to be inspected or on another surface, and wherein the sampling device (3) a) having a first measuring device (16) designed to detect any rotational movement of the roller (9); and / or b) Having a second measuring device (19) designed to detect any contact pressure of the roller (9) on the surface (2) to be inspected. The roller (9) is elastically mounted in the sampling device (3) relative to the surface (2) to be inspected.

2. The particle inspection system (1) according to claim 1, characterized in that, The sampling strip (7) has a sampling surface (8) designed to adhesively pick up the particles (5) from the surface (2) to be inspected, wherein the sampling surface (8) is away from the outer surface (10) of the roller (9) when the sampling strip (7) is guided along the outer surface (10) of the roller (9).

3. The particle inspection system (1) according to claim 2, characterized in that, The sampling surface (8) has a pressure-sensitive adhesive (15) for adhering and extracting the particles (5) from the surface (2) to be inspected.

4. The particle inspection system (1) according to any one of claims 1 to 3, characterized in that, The sampling strip (7) is made of a translucent material.

5. The particle inspection system (1) according to any one of claims 1 to 3, characterized in that, The roller (9) is spring-mounted in the sampling device (3) relative to the surface (2) to be inspected.

6. The particle inspection system (1) according to any one of claims 1 to 3, characterized in that, The first measuring device (16) has an optical sensor (17) or a magnetic sensor to detect the rotation angle of the roller (9), the rotation speed of the roller (9), and / or the angular velocity of the roller (9).

7. The particle inspection system (1) according to any one of claims 1 to 3, characterized in that, The second measuring device (19) has a force sensor (20) to detect the contact pressure of the roller (9) on the surface (2) to be inspected.

8. The particle inspection system (1) according to claim 7, characterized in that, The force sensor (20) is a force sensor with a spring element, an electrodynamic sensor or a piezoelectric sensor.

9. The particle inspection system (1) according to any one of claims 1 to 3, characterized in that, The sampling device (3) has a display (21) to show the user of the sampling device (3) information detected by the first measuring device (16) and / or by the second measuring device (19).

10. The particle inspection system (1) according to claim 9, characterized in that, The display (21) is an electronic display (21).

11. The particle inspection system (1) according to any one of claims 1 to 3, characterized in that, The guide frame (22) can move parallel to the surface to be inspected (2) on or next to the surface to be inspected (2) so as to roll the roller (9) together with the sampling strip (7) against the surface to be inspected (2).

12. The particle inspection system (1) according to any one of claims 1 to 3, characterized in that, The sampling device (3) has an actuator device (26) to move the roller (9) parallel to the surface (2) to be inspected, so as to automatically roll the roller (9) together with the sampling strip (7) against the surface (2) to be inspected.

13. The particle inspection system (1) according to any one of claims 1 to 3, characterized in that, The particle inspection system (1) has an evaluation device (4) designed to evaluate the particles (5) sampled by the sampling strip (7) according to particle size, particle type, particle quantity and / or particle distribution.

14. The particle inspection system (1) according to claim 13, characterized in that, The evaluation device (4) includes a microscope (29).

15. The particle inspection system (1) according to claim 14, characterized in that, The microscope (29) is a transmission light microscope.

16. A projection exposure apparatus (100, 200, 400) for semiconductor lithography, wherein a particle inspection system (1) as described in any one of claims 1 to 15 is provided for inspecting particle contamination on the surface (2) of a component of the projection exposure apparatus (100, 200, 400).

17. The projection exposure apparatus (100, 200, 400) according to claim 16, characterized in that, The particle inspection system (1) is provided for inspecting the surface (2) of the optical elements (415, 416, 418, 419, 420, 108, 201) of the optical units (107, 403, 408) of the projection exposure device (100, 200, 400).

18. A method for inspecting particle contamination on a surface (2), wherein a roller (9) of a sampling device (3) rolls against the surface (2) to be inspected together with a sampling strip (7) guided above the outer surface (10) of the roller (9) to transfer particles (5) from the surface (2) to be inspected to the sampling strip (7), wherein, The sampling device (3) is positioned on or next to the surface (2) to be inspected via a guide frame (22), wherein the guide frame (22) has at least one positioning interface (24, 25), the guide frame (22) being positioned on the surface (2) to be inspected or on another surface via the at least one positioning interface (24, 25), and wherein a) The first measuring device (16) of the sampling device (3) detects any rotational movement of the roller (9); and / or b) The second measuring device (19) of the sampling device (3) detects any contact pressure of the roller (9) on the surface (2) to be inspected. The roller (9) is elastically mounted in the sampling device (3) relative to the surface (2) to be inspected.

19. A computer program product having program encoding means for implementing the method of claim 18 when the program is executed on the control device (6) of the particle inspection system (1).

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