Gas pressure measuring device for measuring a pressure of a process gas at a working site of an apparatus for particle beam-induced processing

Abstract

Gas pressure measuring device (100) for measuring a pressure (P, P1) of a process gas (304) at a working site (306) of an apparatus (300) for particle beam-induced processing of a photomask (302) for microlithography, comprising: a chamber (102) with an opening (104) on a first side (118) for receiving the process gas (304) and a pressure diaphragm (122) on a second side (124), and a sensor unit (134) for detecting a deflection (A) of the pressure diaphragm (122) for ascertaining a pressure (P1) of the process gas (304) in the chamber (102) as a pressure (P) of the process gas (304) at the working site (306), wherein the gas pressure measuring device (100) is set up to be positioned in the apparatus (300) such that its opening (104) is at the working site (306) of the apparatus (300).

Description

[0001] GAS PRESSURE MEASURING DEVICE FOR MEASURING A PRESSURE OF A PROCESS GAS AT A WORKING SITE OF AN APPARATUS FOR PARTICLE BEAM-INDUCED PROCESSING

[0002] The present invention relates to a gas pressure measuring device for measuring a pressure of a process gas at a working site of an apparatus for particle beam-induced processing of a photomask for microlithography, to an arrangement comprising such a gas pressure measuring device and such an apparatus, to a method of calibrating a gas pressure of a process gas at a working site of such an apparatus, to a method of particle beam-induced processing of a photomask for microlithography and to a method of calibrating such a gas pressure measuring device.

[0003] The content of the priority application DE 10 2024 116 280.5 is incorporated by reference in its entirety.

[0004] Microlithography is used to produce microstructured component parts, for example integrated circuits. The microlithography process is performed using a lithography apparatus comprising an illumination system and a projection system. The image of a mask (reticle) illuminated by means of the illumination system is projected here by means of the projection system onto a substrate, for example a silicon wafer, that has been coated with a light-sensitive layer (photoresist) and is arranged in the image plane of the projection system, in order to transfer the mask structure to the light-sensitive coating of the substrate.

[0005] Driven by the desire for ever smaller structures in the production of integrated circuits, EUV lithography apparatuses which use light at a wavelength in the range of 0.1 nm to 30 nm, in particular 13.5 nm, are currently being developed.

[0006] The photomask used in microlithography (i.e. the lithography mask) has microstructures that are projected onto the substrate in reduced scale. The structures of the photomask themselves are already very small and have dimensions of a few micrometres to a few nanometres, for example. In order to produce microstructured components with high accuracy by microlithography, the structures on the photomasks used also have to manufactured very precisely, and the photomasks have to be free of defects (e.g. defective structures and contaminations). Another reason why a defect-free photomask for microlithography is very important is because a photomask is typically used for a multitude of exposures. Therefore, a high degree of time and effort goes into examining photomasks for defects and repairing defects found.

[0007] Typical defects of photomasks include lack of planned structures, for example because an etching process was unsuccessful, or else the presence of unplanned structures, for example because an etching process proceeded too quickly or had its effect at an incorrect site. These defects can be eliminated by selective etching of excess material or by selective removal (depositing) of additional material at the appropriate positions. This is possible in a very targeted manner, for example, by particle beam-induced processing (e.g. focused electron beam-induced processing, FEBIP). This involves providing a particle beam and a process gas (e.g. etching gas or landfill gas) at a point to be processed on the photomask. The particle beam activates a local chemical reaction between a material of the photomask and the process gas, as a result of which material is locally removed from or deposited on the photomask. In the particle beam-induced processing of a photomask, the local gas pressure and gas composition of the process gas are of crucial importance for the processing operation.

[0008] Against this background, it is an object of the present invention to improve particle beam-induced processing of a photomask for microlithography.

[0009] In a first aspect, a gas pressure measuring device for measuring a pressure of a process gas at a working site of an apparatus for particle beam-induced processing of a photomask for microlithography is proposed. The gas pressure measuring device has: a chamber with an opening on a first side for receiving the process gas and a pressure diaphragm on a second side, and a sensor unit for detecting a deflection of the pressure diaphragm for ascertaining a pressure of the process gas in the chamber as a pressure of the process gas at the working site, wherein the gas pressure measuring device is set up to be positioned in the apparatus such that its opening is at the working site of the apparatus. By measuring the pressure of the process gas at the working site of the apparatus for particle beam-induced processing of a photomask for microlithography, the pressure of the process gas can be detected exactly at the site where the process gas is activated by the particle beam in the processing of the photomask. In addition, the pressure of the process gas can be detected where the process gas is part of a chemical reaction by which the photomask is processed (e.g. etched, or material is deposited thereon). In addition, measuring the pressure of the process gas at the working site of the apparatus can give better control of the pressure of the process gas (e.g. better adjustment). It is thus possible to improve the particle beam-induced processing of the photomask.

[0010] In addition, the proposed gas pressure measuring device has a chamber with an opening through which a sample of the process gas penetrates into the chamber, such that its pressure can be measured therein. This eliminates the need for a gas conduit, such as a gas tube, to guide the process gas from the working site to a location remote from the working site (e.g. to a pressure gauge outside a vacuum chamber of the apparatus). This is advantageous because such a gas conduit has a large surface area that leads to measurement errors in pressure measurement as a result of leaks and desorption.

[0011] The proposed gas pressure measuring device is additionally disposed at the working site of the apparatus, i.e. also within a process atmosphere with very low pressure (e.g. within a high vacuum with a pressure of 107mbar or less and / or within a vacuum chamber of the apparatus). The pressure differential between a process gas pressure to be measured in the chamber of the gas pressure measuring device and an external pressure of the chamber of the gas pressure measuring device is thus much smaller than if a pressure gauge outside the process atmosphere (e.g. outside the vacuum chamber) is used, where the process gas pressure is measured against the atmospheric pressure. Consequently, the proposed gas pressure measuring device can be used to detect very small pressure values, e.g. pressure values in the order of down to 10’6mbar or 107mbar. By contrast, a pressure gauge outside the process atmosphere which is capable of measuring a gas pressure irrespective of the type of gas and also corrosive gases can detect only a measurement range down to about 104mbar. The apparatus for particle beam-induced processing of a photomask for microlithography serves, for example, to repair a defect in the photomask. The defect is, for example, an unwanted structure (e.g. an unwanted absorber structure) of the photomask which is etched with the apparatus. This means that material is removed locally from the photomask in the region of the defect. The defect may also be a missing structure (e.g. a missing absorber structure) of the photomask which is deposited with the apparatus. This means that material (a deposit) is deposited locally on the photomask in the region of the defect.

[0012] The apparatus is used to provide a particle beam, for example an electron beam or an ion beam, and a process gas at a site on the photomask to be processed. The particle beam activates a local chemical reaction between a material of the photomask and the process gas, as a result of which material is locally removed from the photomask or deposited on the photomask.

[0013] The process gas comprises an etching gas for example. The etching gas comprises, for example, xenon difluoride (XeF2), sulfur hexafluoride (SFe), sulfur tetrafluoride (SF4), nitrogen trifluoride (NF3), phosphorus trifluoride (PF3), tungsten hexafluoride (WFe), tungsten hexachloride (WCk), molybdenum hexafluoride (MoFe), hydrogen fluoride (HF), nitrogen oxygen fluoride (NOF) and / or triphosphorus trinitrogen hexafluoride (P3N3F6).

[0014] The process gas includes, for example, a deposition gas and / or precursor gas. Suitable deposition gases and / or precursor gases for deposition or growth of raised structures (e.g. deposits) especially include alkyl compounds of main group elements, metals or transition elements. Examples thereof include cyclopentadi- enyl(trimethyl)platinum (CpPtMes Me = CH4), methylcyclopentadienyl(trime- thyl)platinum (MeCpPtMes), tetramethyltin (SnMe4), trimethylgallium (GaMes), ferrocene (Cp2Fe), bis arylchromium (Ar2Cr), and / or carbonyl compounds of main group elements, metals or transition elements, such as for example chromium hexacarbonyl (Cr(CO)e), molybdenum hexacarbonyl (Mo(CO)e), tungsten hexacarbonyl (W(CO)e), dicobalt octacarbonyl (602(00)3), triruthenium dodecacarbonyl (Ru3(CO)i2), iron pentacarbonyl (Fe(CO)s), and / or alkoxide compounds of main group elements, metals or transition elements, for example tetraethoxysilane (Si(OC2Hs)4), tetraisopropoxytitanium (TiCOCsHy ), and / or halide compounds of main group elements, metals or transition elements, such as for example tungsten hexafluoride (WFe), tungsten hexachloride (WClc), titanium tetrachloride (TiCU), boron trifluoride (BCI3), silicon tetrachloride (SiCU), and / or complexes with main group elements, metals or transition elements, for example copper bis(hexafluoroacetylacetonate) (CulCrFcHChD, dimethylgold trifluoroacety lacetonate (Me^AulCrF.'H 1O2)), and / or organic compounds such as carbon monoxide (CO), carbon dioxide (CO2), aliphatic and / or aromatic hydrocarbons, and the like.

[0015] The process gas comprises an added gas for example. Added gases include, for example, oxygenous and / or oxidizing gases such as oxygen (O2), ozone (O3), water (H2O), hydrogen peroxide (H2O2), nitrous oxide (N2O), nitric oxide (NO), nitrogen dioxide (NO2), nitric acid (HNO3) and other oxygenous gases, and / or halides such as chlorine (CI2), hydrogen chloride (HC1), hydrogen fluoride (HF), iodine (I2), hydrogen iodide (HI), bromine (Br2), hydrogen bromide (HBr), phosphorus trichloride (PCI3), phosphorus pentachloride (PCI5), phosphorus trifluoride (PF3) and other halogen-containing gases (e.g. CF4, NOCI), and / or reducing gases, such as hydrogen (H2), ammonia (NH3), methane (CH4) and other hydrogenous gases. These added gases can be used, for example, for etching processes, as buffer gases, as passivating media and the like.

[0016] The photomask for microlithography is, for example, a photomask for use in an EUV lithography apparatus. EUV here stands for "extreme ultraviolet" and denotes a wavelength of the operating light of between 0.1 nm and 30 nm, in particular 13.5 nm. At these wavelengths it is necessary to use reflective optical elements, and this applies to the photomask as well. In an EUV lithography apparatus, a beam shaping and illumination system is used to guide EUV radiation to the photomask ("reticle"), which takes the form of a reflective photomask. Therefore, the photomask comprises a layer that reflects EUV radiation and e.g. takes the form of a Bragg mirror, and a structured absorbing layer ("absorber structures") on the reflective surface. Such masks are also referred to as binary lithography masks. The pattern of the structured absorbing layer (i.e. the pattern of the absorber structures) of the photomask is imaged with reduced size on a wafer by means of a projection system of the EUV lithography apparatus. For example, the photomask for microlithography comprises a substrate, a reflective multilayer coating disposed on the substrate and a structured coating disposed thereon. In addition, for example, there may also be a capping layer including ruthenium, for example, disposed between the multilayer coating and the structured coating.

[0017] By way of example, the substrate comprises silicon dioxide (SiO2), for example fused quartz. For example, the multilayer coating comprises an alternating sequence of molybdenum and silicon layers. For example, the structured coating comprises tantalum, one or more tantalum compounds, tantalum nitride and / or tantalum oxide. The substrate, the multilayer coating and / or the structured coating (absorber structures) may also comprise other materials.

[0018] The photomask for microlithography may, however, for example, also be a photomask for use in a DUV lithography system. DUV here stands for "deep ultraviolet" and denotes a wavelength of the working light of between 30 nm and 250 nm, in particular 193 nm or 248 nm. A photomask for a DUV lithography system takes the form in particular of a transmissive optical element (transmissive photomask).

[0019] When the photomask is processed with the apparatus for particle beam-induced processing, the photomask is provided in a process atmosphere of the apparatus. For example, the process atmosphere is an atmosphere with a controlled composition and a controlled pressure (for example in the range from 102to 10’8mbar). For example, the process atmosphere is a high vacuum with a pressure of 107mbar or less. For example, the process atmosphere is provided within an evacuated housing (for example in a vacuum chamber) of the apparatus. In addition, in the processing of the photomask with the apparatus, at least one process gas and the particle beam are provided in the process atmosphere.

[0020] The working site of the apparatus for particle beam-induced processing of a photomask comprises, in particular, a focal point of the particle beam. The working site of the apparatus comprises, in particular, a focal point of the particle beam in a plane of the apparatus which is set up for positioning of the photomask. In a state in which a photomask is positioned in the apparatus for processing the photomask, the working site of the apparatus comprises, in particular, a site on the photomask in which the focused particle beam hits the photomask. For example, the working site of the apparatus comprises a region on the photomask over which the focused particle beam is typically scanned over the photomask in order to repair a typical defect of the photomask. In other words, the working site of the apparatus includes, for example, a typical defect region of the photomask.

[0021] The gas pressure measuring device is disposed in particular in place of a photomask in the apparatus for particle beam-induced processing. This means that either particle beam-induced processing of the photomask takes place or a pressure of a process gas is measured with the gas pressure measuring device. In a state in which the gas pressure measuring device is positioned in the apparatus for measuring the gas pressure, the gas pressure measuring device is positioned in particular in such a way that the opening of the chamber of the gas pressure measuring device is at the working site of the apparatus. In other words, the opening of the chamber of the gas pressure measuring device is exactly at the site where, in the state of processing of a photomask, the process gas and the particle beam meet on the photomask (for example including the defect area of the photomask).

[0022] The gas pressure measuring device is in particular set up for positioning in the process atmosphere and / or within the vacuum chamber of the apparatus for particle beam-induced processing.

[0023] The gas pressure measuring device is set up, for example, for positioning between a sample stage and a gas nozzle of the apparatus for particle beam-induced processing of a photomask.

[0024] The chamber of the gas pressure measuring device serves to accommodate the process gas in order to ascertain a pressure of the process gas in an interior space of the chamber. In particular, the chamber includes the opening through which the process gas can penetrate into the interior space of the chamber. For example, the opening has a round and / or circular shape. However, the opening may also have a different shape. The process gas is fed, for example, from a gas provision device of the apparatus into an exterior space of the chamber adjacent to the opening of the chamber. The process gas then penetrates through the opening into the chamber until a gas pressure of the process gas in the interior space of the chamber is equal to a gas pressure of the process gas in the exterior space of the chamber adjacent to the opening of the chamber.

[0025] The chamber of the gas pressure measuring device is in particular a chamber which is closed apart from the opening. The chamber has a chamber wall that fully encloses the interior space (cavity) of the chamber except for the opening.

[0026] For example, the chamber of the gas pressure measuring device is cuboidal in shape. The chamber of the gas pressure measuring device may, for example, also be cylindrical in shape (for example with a circular base).

[0027] For example, the first and second sides of the chamber are formed correspondingly by a first and second section of the chamber wall. The first and second sections of the chamber wall are arranged in particular in different planes from one another. In addition, the first and second sides of the chamber and hence the first and second sections of the chamber wall are arranged, for example, parallel or at an angle to one another. For example, the second side of the chamber and hence the second section of the chamber wall is arranged opposite (for example also parallel to) the first side of the chamber and hence the first section of the chamber wall. Alternatively, the second side of the chamber and hence the second section of the chamber wall is arranged at an angle (e.g. perpendicular) to the first side of the chamber and hence to the first section of the chamber wall. An angled arrangement has the advantage that the gas pressure measuring device may be of a small design, and it is possible to save build space, especially build height.

[0028] The pressure diaphragm is disposed on the second side of the chamber. The pressure diaphragm is a flexible membrane that forms a section of a chamber wall of the chamber. The pressure diaphragm thus separates the interior space of the chamber from an exterior space of the chamber. An inner face of the pressure diaphragm is thus subject to the gas pressure within the chamber, and an outer face of the pressure diaphragm is subject to a gas pressure in an exterior space of the chamber. The pressure diaphragm is set up to be deflected from a rest position to a deflected position in the event of a pressure differential between the interior space and the exterior space. The extent of deflection depends on the extent of the pressure differential.

[0029] In the present context, a distinction is made in particular between a first exterior space of the chamber and a second exterior space of the chamber. The first exterior space of the chamber is adjacent to the first side of the chamber, in particular adjacent to the opening on the first side of the chamber. The first exterior space of the chamber includes the working site of the apparatus. The process gas is provided in the first exterior space of the chamber, for example by a gas provision device of the apparatus. The second exterior space of the chamber is adjacent to the second side of the chamber. By providing the process gas in the first exterior space of the chamber and penetration of the process gas through the opening into the chamber, a pressure equilibrium is established in the first exterior space of the chamber and the interior space of the chamber. A measurement of the gas pressure of the process gas in the chamber thus allows conclusions to be drawn as to the gas pressure of the process gas in the first exterior space of the chamber and hence at the working site of the apparatus.

[0030] The pressure diaphragm is disposed on the second side of the chamber and hence separates the interior space of the chamber from the second exterior space of the chamber. If there is a pressure differential between a gas pressure of the process gas in the chamber interior space and a gas pressure of a gas in the second exterior space of the chamber, the pressure diaphragm is deflected from its rest position. In particular, if the gas pressure in the interior space of the chamber is greater than in the second exterior space of the chamber, the pressure diaphragm will bulge into the second exterior space of the chamber. The pressure diaphragm is thus designed to determine a pressure of the process gas in the chamber based on a pressure differential from a gas pressure of a gas outside the chamber - in the second exterior space of the chamber. For example, the atmosphere in the second exterior space of the chamber is the process atmosphere, such as a high vacuum (i.e. a pressure of 107mbar or less).

[0031] A material of the pressure diaphragm comprises, for example, a material that is resistant to the process gases used in the apparatus for particle beam-induced processing. For example, a material of the pressure diaphragm comprises one or more metals, steel, stainless steel, aluminium, one or more nickel alloys, one or more nickel-copper alloys (e.g. Monel), one or more plastics (e.g. Kapton, polyamide).

[0032] The sensor unit for detecting a deflection of the pressure diaphragm is set up in particular to detect sensor data that are indicative of a deflection of the pressure diaphragm. The sensor unit is additionally set up, for example, to transmit the sensor data detected to a control device. The control device is, for example, part of a higher arrangement including the gas pressure measuring device. The higher arrangement may also include, for example, the apparatus for particle beam-induced processing. The control device may, for example, also be part of the apparatus for particle beam-induced processing.

[0033] For example, the sensor unit is positioned opposite the second side of the chamber.

[0034] For example, the sensor unit is set up to detect a deflection of the pressure diaphragm in the range of about 1 pm to 1 nm.

[0035] For example, the gas pressure measuring device is set up to detect a pressure of the process gas in the range of 0.1 mbar to 107mbar.

[0036] The gas pressure measuring device may also include more than one sensor unit for detecting a deflection of the pressure diaphragm.

[0037] In one embodiment of the first aspect: the pressure diaphragm forms a section of a wall of the chamber and the sensor unit is disposed outside the chamber, the sensor unit is set up to detect a distance between a sensor surface of the sensor unit and a surface of the pressure diaphragm at its maximum deflection, and / or the pressure diaphragm includes an electrically conductive material and the sensor unit is set up to detect a capacitance between the sensor surface of the sensor unit and the pressure diaphragm.

[0038] The pressure diaphragm has the maximum deflection, for example, in a central region of the pressure diaphragm. If the sensor unit is set up to detect the distance between the sensor surface and the surface of the pressure diaphragm, it can also be stated that the sensor unit has a distance sensor. For example, the sensor unit in this case is set up to detect a distance based on a capacitive measurement, a confocal measurement, and / or an interferometric measurement. In the case of a capacitive measurement, the pressure diaphragm includes the electrically conductive material and the sensor unit is set up to detect a capacitance between the sensor surface and the pressure diaphragm and either to give the measured capacitance as sensor data output or to give a distance from the pressure diaphragm determined therefrom as sensor data output.

[0039] A control device as described above may, for example, be set up to determine a pressure of the process gas in the chamber (and hence at the working site of the apparatus) based on sensor data from the sensor unit that include a distance and / or a capacitance. For example, the gas pressure can be determined from the distance detected or directly from the measured capacitance.

[0040] In a further embodiment of the first aspect, the pressure diaphragm includes an electrically conductive material, and the sensor unit is a capacitive sensor unit.

[0041] A capacitive sensor unit has the advantage that it is based on a purely electronic measurement principle and can be connected to devices in the environment via electrical wires (e.g. bushings). A capacitive sensor unit is additionally simple and inexpensive to produce. In addition, a capacitive sensor unit can be provided as a sensor unit with very small and / or compact external dimensions. This is advantageous in order to position the gas pressure measuring device at the working site of the apparatus (i.e. in place of a photomask).

[0042] In a further embodiment of the first aspect, a size and / or a diameter of the opening of the chamber is 100 pm or less, 50 pm or less, 30 pm or less, 10 pm or less and / or 5 pm or less.

[0043] This allows the pressure of the process gas to be measured with high spatial resolution. In particular, the smaller the opening of the chamber of the gas pressure measuring device, the greater the spatial resolution of the pressure measurement.

[0044] Since high spatial variation of the gas pressure of the process gas is to be expected at the working site of the apparatus for particle beam-induced processing, it is advantageous to determine the gas pressure of the process gas with a correspondingly high spatial resolution.

[0045] In a further embodiment of the first aspect, the gas pressure measuring device is set up for positioning within the apparatus such that the first side of the chamber is opposite a gas nozzle of the apparatus.

[0046] What is meant, for example, by the first side of the chamber being opposite the gas nozzle of the apparatus is that a gas stream / gas flow from the gas nozzle of the apparatus flows in the direction of the first side of the chamber of the gas pressure measuring device. For example, the first side of the chamber relative to the gas nozzle of the apparatus is arranged such that a gas flow from the gas nozzle hits the first side of the chamber at an angle between 30° and 90° or between 45° and 90°.

[0047] The gas nozzle of the apparatus is in particular a gas nozzle of a gas provision device of the apparatus. For example, the gas nozzle of the apparatus is a ring nozzle. For example, the apparatus is arranged in such a way that a particle beam is radiated through a centre of the ring nozzle.

[0048] In a further embodiment of the first aspect, the chamber on the first side has a flat outer surface with the opening, and the flat outer surface is set up to completely cover the area of the gas nozzle.

[0049] The gas pressure measuring device is disposed in place of the photomask in the apparatus for particle beam-induced processing of the photomask. In order to be able to infer a gas pressure of the process gas with maximum accuracy with the gas pressure measuring device in the processing of the photomask, it is advantageous when geometric dimensions of the gas pressure measuring device, in particular the chamber, are similar to geometric dimensions of a typical photomask. In the case of a photomask, the surface thereof is sufficiently broad to influence the outflow of the gas flow flowing out of a gas nozzle and hence also increase the gas pressure at the working site. The gas pressure measuring device, in particular the chamber, is therefore geometrically designed so that this behaviour of a photomask is reproduced accordingly.

[0050] The flat outer surface of the chamber is in particular a surface which faces away from an interior space of the chamber and faces towards an exterior space of the chamber (in particular the first exterior space of the chamber).

[0051] The flat outer surface of the chamber includes the opening in particular. It can also be stated that the flat outer surface of the chamber is interrupted by the opening.

[0052] What is meant in particular by the flat outer surface completely covering the area of the gas nozzle is that the flat outer surface completely covers the gas nozzle in relation to an area (e.g. a total area) of the gas nozzle.

[0053] For example, a size of the flat outer surface of the chamber is equal to or greater than an area (e.g. total area) covered by a gas nozzle.

[0054] In a further embodiment of the first aspect, the gas pressure measuring device has at least one temperature sensor for detecting a temperature of the pressure diaphragm and / or the sensor unit.

[0055] The at least one temperature sensor can be used to detect thermal drift in the course of pressure measurement. In particular, a change in temperature of the pressure diaphragm and / or the sensor unit (for example a sensor surface of the sensor unit) can change the pressure dependence of the deflection of the pressure diaphragm so as to alter a degree of deflection of the pressure diaphragm at a particular gas pressure in the chamber depending on temperature. A change in temperature can also change a distance between the pressure diaphragm and the sensor unit, e.g. the sensor surface, in the rest position of the pressure diaphragm. In addition, a change in temperature of the sensor unit may result in a change in sensitivity and / or a zero point of the sensor unit. The at least one temperature sensor is set up to acquire temperature data from the pressure diaphragm and / or the sensor unit. A pressure measurement can then be made with the gas pressure measuring device based on the temperature data acquired. For example, a pressure measurement with the gas pressure measuring device can be conducted only when it is ascertained on the basis of the recorded temperature data that the gas pressure measuring device, e.g. the pressure diaphragm and / or the sensor unit, has thermally stabilized. For example, a pressure measurement with the gas pressure measuring device can also be conducted in such a way that the detected deflection of the pressure diaphragm is calibrated on the basis of the acquired temperature data and a lookup table.

[0056] The gas pressure measuring device may also have more than one temperature sensor for detecting a temperature of the pressure diaphragm and / or the sensor unit.

[0057] In a second aspect, an arrangement comprising an apparatus for particle beam- induced processing of a photomask for microlithography and a gas pressure measuring device as described above is proposed.

[0058] The apparatus for particle beam-induced processing of a photomask for microlithography has a particle beam provision device for provision of an activating particle beam on a surface of the photomask. The apparatus additionally comprises a gas provision device for providing at least one process gas at the surface of the photomask. The at least one process gas especially comprises at least one process gas which is activatable by the particle beam, such that the photomask can be processed by means of the activated process gas.

[0059] For example, the apparatus is a repair apparatus for repairing photomasks for microlithography. For example, the apparatus is a modified scanning electron microscope.

[0060] The apparatus for particle beam-induced processing of a photomask comprises, for example, a sample stage for arranging, holding and positioning the photomask to be processed. The sample stage is actuatable, for example, in two or preferably in three spatial directions. Moreover, the sample stage may be mounted in tiltable and rotatable fashion in order to position the photomask.

[0061] The particle beam provision device comprises, for example, a particle source (e.g. electron source or ion source) for generating the particle beam (e.g. electron beam or ion beam); a particle beam guiding device (e.g. scanning unit) which is set up to direct the particle beam to a particular pixel of a repair region of the photomask; a particle beam shaping device (e.g. particle, electron and / or beam optics unit) which is set up to shape, in particular to focus, the particle beam; and at least one detector for detecting secondary electrons and / or backscattered electrons.

[0062] The gas provision device comprises, for example, at least one storage vessel which is set up to store the at least one process gas. The gas provision device can additionally or instead, for example, also comprise at least one gas generation device which is set up to produce the at least one process gas. The gas provision device further comprises at least one gas flow rate adjustment unit which is set up to provide the at least one process gas with a predetermined gas flow rate at the surface of the photomask. The gas provision device further comprises, for example, at least one supply conduit (e.g. a supply duct) which is set up to feed the at least one process gas to the surface of the photomask. The gas provision device further comprises at least one nozzle, for example at the end of the supply conduit, in order to release the at least one process gas at the surface of the photomask.

[0063] The activating particle beam is provided, for example, by means of the particle beam guiding device, successively at each pixel of a region of a defect (e.g. a repair form of the defect) of the photomask. The activating particle beam remains at each pixel for a predetermined dwell time in order to initiate the chemical reaction between the at least one process gas and a mask material at the site of the respective pixel. For example, the dwell time is 100 ns. However, the dwell time may also adopt other values.

[0064] The apparatus for particle beam-induced processing of a photomask and / or the arrangement comprising the apparatus includes a control device, for example. The control device is set up, for example, to receive sensor data from the sensor unit of the gas pressure measuring device. The sensor data are in particular directly or indirectly indicative of a degree of deflection of the pressure diaphragm of the gas pressure measuring device. The sensor data include, merely by way of example, distance data and / or capacitance data from the pressure diaphragm. The control device is also set up, for example, to determine a pressure of the process gas in the chamber of the gas pressure measuring device based on the sensor data as a pressure of the process gas at the working site.

[0065] In one embodiment of the second aspect, the gas pressure measuring device is secured so as to be movable within the apparatus for particle beam-induced processing such that the gas pressure measuring device is movable from a parked position to a working position and back. In the working position, the opening of the chamber of the gas pressure measuring device is disposed at the working site of the apparatus

[0066] In this way, a photomask for processing the photomask and the gas pressure measuring device for measuring a pressure of a process gas may electively be disposed at the working site of the apparatus for particle beam-induced processing. For example, the gas pressure measuring device may first be disposed at the working site of the apparatus in order to measure a pressure of at least one predetermined process gas. A photomask may subsequently be disposed at the working site of the apparatus in order to process the photomask with the at least one predetermined process gas.

[0067] If the gas pressure measuring device is disposed in the working position, the opening of the chamber of the gas pressure measuring device is disposed, for example, opposite a gas nozzle of the gas provision device of the apparatus

[0068] The gas pressure measuring device is secured, for example, to a mount of the apparatus for particle beam -induced processing such that the gas pressure measuring device is movable to the working position by means of the mount.

[0069] The gas pressure measuring device is secured, for example, so as to be movable within the apparatus for particle beam-induced processing such that the gas pressure measuring device is slidable (translational movement) and / or pivotable (rotational movement) from the parked position to the working position and back.

[0070] Merely by way of example, the gas pressure measuring device is secured to the sample stage of the apparatus for particle beam-induced processing. In a first example, a supporting surface of the sample stage has a mask region for positioning of the photomask and a border region other than the mask region (e.g. disjunct from the mask region). In addition, the gas pressure measuring device is secured to the sample stage, for example, in the edge region of the sample stage and can be moved to the working position by means of the displaceable sample stage. In a second example, the gas pressure measuring device is secured to a mount which is secured movably (e.g. pivotably) to the sample stage.

[0071] In one embodiment of the second aspect: the apparatus for particle beam-induced processing comprises at least one gas provision device for providing at least one process gas at the working site, the at least one gas provision device has a gas flow rate adjustment unit for adjusting at least one gas parameter indicative of a gas flow rate of the process gas provided, and the arrangement has a control device designed for the purpose of, for a respective process gas: ascertaining a pressure of the process gas in the chamber of the gas pressure measuring device based on the detected deflection of the pressure diaphragm of the gas pressure measuring device, by ascertaining pressure values of the process gas for different values of the at least one gas parameter indicative of the gas flow rate, and ascertaining a calibration table that has the ascertained pressure values as pressure values of the process gas at the working site of the apparatus assigned to the different values of the at least one gas parameter of the process gas.

[0072] Using the calibration table ascertained, the gas parameter indicative of the gas flow rate (e.g. a temperature and / or a gas flow rate) can be established in a gas provision device for the process gas in question such that it corresponds to the pressure of the process gas at the working site according to the calibration table. For example, the gas provision device has a pressurized gas vessel, and the gas flow rate adjustment unit is set up to adjust a gas flow rate of the process gas (for example directly) (for example also by means of one or more valves).

[0073] For example, the gas provision device has a reservoir for a liquid and / or a solid from which the process gas evaporates. In addition, the gas flow rate adjustment unit is set up, for example, to set a temperature of the liquid or solid such that the resulting vapour pressure determines the gas flow rate of the process gas. In particular, the temperature to be set may be below the ambient temperature.

[0074] The calibration table for a particular process gas includes, in particular, the different values of the gas parameter of the process gas which is indicative of the gas flow rate, and ascertained pressure values of the process gas in the chamber of the gas pressure measuring device and hence at the working site of the apparatus which are assigned to these values of the gas parameter.

[0075] In a third aspect, a method of calibrating a gas pressure of a process gas at a working site of an apparatus for particle beam-induced processing of a photomask for microlithography is proposed. The method comprises the steps ofl al) positioning a gas pressure measuring device, in particular a gas pressure measuring device as described above, in the apparatus such that an opening of a chamber of the gas pressure measuring device is present at the working site of the apparatus, b 1) feeding a process gas to the working site and causing the process gas to penetrate through the opening into the chamber of the gas pressure measuring device, where the process gas is fed in successively with different values of at least one gas parameter indicative of a gas flow rate of the process gas, cl) ascertaining a pressure of the process gas using the gas pressure measuring device depending on the different values of the at least one gas parameter, and dl) ascertaining a calibration table that has the ascertained pressure values as pressure values of the process gas at the working site of the apparatus assigned to the different values of the at least one gas parameter. For example, by the calibration method according to the third aspect, the gas pressure of one or more process gases at the working site of the apparatus can be calibrated prior to each processing operation on a particular photomask with the apparatus or prior to each processing operation on a particular defect of the photomask with the apparatus. Alternatively or additionally, the calibration method according to the third aspect can also be performed after predetermined maintenance periods (for example once or twice per year or in other maintenance periods) and / or after servicing operations on the apparatus and / or a repair of the apparatus.

[0076] For example, steps bl) to dl) can be repeated for further process gases, such that a calibration table is ascertained for each process gas.

[0077] For example, steps bl) to dl) can be performed for all predetermined process gases required for a processing operation on a photomask and / or a processing operation on a particular defect of a photomask. For example, steps bl) to dl) can be performed for all predetermined process gases prior to the beginning of processing of the photomask with the predetermined process gases. Alternatively, in the event of an exchange from processing of the photomask with one process gas to processing of the photomask with a further (different) process gas, steps bl) to dl) may be performed for the further process gas.

[0078] In a fourth aspect, a method of particle beam-induced processing of a photomask for microlithography is proposed. The method comprises the steps of: a2) providing at least one calibration table for at least one process gas, where the calibration table has pressure values of the process gas at a working site of the apparatus assigned to different values of at least one gas parameter of the process gas which is indicative of a gas flow rate, b2) positioning a photomask in the apparatus such that a portion of the photomask to be processed is at the working site, and c2) establishing a predetermined pressure value of the at least one process gas at the working site by adjusting the at least one parameter indicative of the gas flow rate of the at least one process gas based on the at least one calibration table provided, and d2) particle beam-induced processing of the photomask using the at least one process gas and a particle beam.

[0079] For example, the section of the photomask to be processed is a defect region and / or repair region (e.g. a repair shape) of the photomask.

[0080] Consequently, it is first possible to predetermine a pressure value of the at least one process gas at the working site which is required for the processing of the photomask (for example for processing of a predetermined defect of the photomask). It is subsequently possible to establish the pressure value of the at least one process gas which is required at the working site on the basis of the calibration table by adjusting the gas parameter (for example in the gas provision device).

[0081] This allows better adjustability of the pressure of the process gas at the working site (for example including with a higher spatial resolution).

[0082] In one embodiment of the fourth aspect, the at least one calibration table is ascertained and provided on the basis of the above-described method (calibration method) according to the third aspect.

[0083] In a further embodiment of the fourth aspect, the at least one calibration table is ascertained on the basis of the above-described method according to the third aspect by means of a first apparatus for particle beam-induced processing of a photomask for microlithography. In addition, steps b2) to d2) are performed using a second apparatus, different from the first apparatus, for particle beam-induced processing of a photomask for microlithography.

[0084] In particular, the first and second apparatus for particle beam-induced processing is not the same apparatus. However, the first and second apparatus for particle beam-induced processing are similar to one another such that a calibration table determined by means of the first apparatus is usable for the second apparatus. In a fifth aspect, a method of calibrating a gas pressure measuring device as described above is proposed. The method comprises the steps of: a3) feeding a calibration gas at a predetermined pressure to the opening of the chamber of the gas pressure measuring device, b3) causing the calibration gas to penetrate through the opening into the chamber, and c3) ascertaining a pressure of the calibration gas in the chamber based on the detected deflection of the pressure diaphragm of the gas pressure measuring device.

[0085] In this way, it is possible to calibrate the gas pressure measuring device itself - especially prior to use thereof in the apparatus for particle beam-induced processing of a photomask. In particular, it is possible to calibrate the assignment of a pressure value to a degree of deflection of the pressure diaphragm. This also allows compensation for mechanical tolerances, such that it is possible to produce several examples of the gas pressure measuring device that give comparable results. In addition, it is possible to check whether a gas pressure measuring device still fulfils a required accuracy after a certain period of utilization.

[0086] During the performance of the method in the fifth aspect, the gas pressure measuring device is in particular not disposed in the apparatus for particle beam-induced processing of a photomask. Instead, a separate gas provision device is disposed adjacent to the first side of the chamber of the gas pressure measuring device. The separate gas provision device has, for example, a reservoir for a liquid and / or a solid with adjustable temperature, from which the calibration gas evaporates, where the gas pressure is adjustable via the temperature of the liquid or the solid. The separate gas provision device may, for example, also have a pressure vessel, where the gas pressure is adjustable.

[0087] The calibration gas is supplied to the opening of the chamber of the gas pressure measuring device at the predetermined pressure, for example by supplying a predetermined vapour pressure by setting a temperature of a liquid and / or a solid in a reservoir or by setting a reproducible gas flow rate. The gas flow rate can be calculated, for example, by the weight loss of a Knudsen cell. "A" or "an" in the present context should not necessarily be regarded as a restriction to exactly one element. Instead, a plurality of elements, for example two, three or more, may also be provided. Nor should any other numeral used here be understood to the effect that there is a restriction to exactly the stated number of elements. Instead, unless indicated otherwise, numerical variances upward and downward are possible.

[0088] The embodiments and features described for the first aspect are correspondingly applicable to the second to fifth aspects, and vice versa.

[0089] Further possible implementations of the invention also include combinations which have not been mentioned explicitly of features or embodiments described above or hereinafter with regard to the working examples. A person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

[0090] Further advantageous configurations and aspects of the invention are the subject of the dependent claims and of the working examples of the invention that are described hereinafter. The invention is elucidated in detail hereinafter by preferred embodiments with reference to the appended figures.

[0091] Fig. 1 shows a gas pressure measuring device according to a first embodiment;

[0092] Fig. 2 shows a gas pressure measuring device according to a second embodiment;

[0093] Fig. 3 shows an arrangement comprising an apparatus for particle beam-induced processing of a photomask for microlithography in one embodiment;

[0094] Fig. 4 shows a detail from Fig. 3, showing a sample stage of the apparatus in a different position;

[0095] Fig. 5 shows a sample stage of the apparatus from Fig. 3 with a gas pressure measuring device from Fig. 1 or 2 which is movably secured thereto; Fig. 6 shows a gas provision device of the apparatus from Fig. 3 in one embodiment;

[0096] Fig. 7 shows a gas provision device of the apparatus from Fig. 3 in a further embodiment;

[0097] Fig. 8 illustrates functional components of a control device of the arrangement from Fig. 3 in one embodiment;

[0098] Fig. 9 shows a flow diagram of a method of calibrating a gas pressure of a process gas at a working site of an apparatus for particle beam-induced processing of a photomask for microlithography in one embodiment;

[0099] Fig. 10 shows a flow diagram of a method of particle beam-induced processing of a photomask for microlithography in one embodiment; and

[0100] Fig. 11 shows a flow diagram of a method of calibrating a gas pressure measuring device in one embodiment.

[0101] In the figures, identical or functionally identical elements have been given the same reference symbols, unless indicated otherwise. It should also be noted that the representations in the figures are not necessarily true to scale.

[0102] Fig. 1 shows a gas pressure measuring device 100 in a first embodiment. The gas pressure measuring device 100 can be used in an apparatus 300 (Fig. 3) for particle beam-induced processing of a photomask 302 for microlithography. The gas pressure measuring device 100 is set up in particular to determine a pressure P of a process gas 304 (Fig. 3) of the apparatus 300 at a working site 306 of the apparatus 300.

[0103] As can be seen in Fig. 1, the gas pressure measuring device 100 has a chamber 102 for receiving the process gas 304. The reference symbol F indicates a gas flow rate of the process gas 304, which is provided, for example, by a gas provision device 308 of the apparatus 300 (Fig. 3). The chamber 102 has, in particular, an opening 104 through which the process gas 304 can penetrate into an interior space 106 of the chamber 102. For example, the opening 104 has a circular shape! however, the opening may also have a shape other than a circular shape. The chamber 102 comprises a chamber wall 108 with several sections 110, 112, 114, 116. The opening 104 is formed as a passage opening in the chamber wall 108, in particular in a first section 110 of the chamber wall 108. The opening 104 is additionally formed on a first side 118 of the chamber 102. In other words, the first side 118 of chamber 102 is formed by the first section 110 of the chamber wall 108.

[0104] The process gas 304 is fed, for example, from the gas provision device 308 of the apparatus 300 (Fig. 3) into an exterior space 120 of the chamber 102 that adjoins the opening 104 of the chamber 102 (first exterior space 120 of the chamber 102). For example, the gas pressure measuring device 100 is set up for positioning within the apparatus 300 such that the first side 118 of the chamber 102 is opposite a gas nozzle 340 of the apparatus 300 (Fig. 3). The process gas 304 then penetrates through the opening 104 into the interior space 106 of the chamber 102 until a gas pressure Pl of the process gas 304 in the interior space 106 of the chamber 102 is equal to a gas pressure P2 of the process gas 304 in the first exterior space 120 of the chamber 102 adjacent to the opening 104 of the chamber 102.

[0105] The chamber 102 also has a pressure diaphragm 122 on a second side 124 of the chamber 102. The pressure diaphragm 122 can be used to determine the pressure Pl of the process gas 304 in the interior space 106 of the chamber 102. For example, the pressure diaphragm 122 forms a second section 112 of the chamber wall 108. The pressure diaphragm 122 is fixed, for example, at its first end in a section 114 of the chamber wall 108 and is fixed at its second end in a section 116 of the chamber wall 108. In addition, the pressure diaphragm 122 separates the interior space 106 of the chamber 102 from a second exterior space 126 of the chamber 102. The pressure diaphragm 122 is set up, in the event of a pressure differential between the pressure Pl of the process gas 304 in the interior space 106 of the chamber 102 and a pressure P3 of a gas 128 in the second exterior space 126 of the chamber 102, to be deflected from a rest position 130 into a deflected position 132. The extent of deflection A depends on the extent of the pressure differential AP = Pl - P3. As illustrated in Fig. 1, it is not the case that the pressure P2, P3 is the same throughout the exterior space 120, 126 of the chamber 102. Instead, there is a pressure P2 in the first exterior space 120 adjacent to the first side 118 and to the opening 104 of the chamber 102. The first exterior space 120 of the chamber 102 includes, in particular, the working site 306 of the apparatus 300 (Fig. 3). The process gas 304 is provided in the first exterior space 120 of the chamber 102, for example by the gas provision device 308 of the apparatus 300 (Fig. 3). By providing the process gas 304 in the first exterior space 120 of the chamber 102 and penetration of the process gas 304 through the opening 104 into the chamber 102, a pressure equilibrium Pl = P2 is established in the first exterior space 120 and the interior space 106 of the chamber 102. In equilibrium, the pressure Pl in the interior space 106 and the pressure P2 in the first exterior space 120 are the same. A measurement of the gas pressure Pl of the process gas 304 in the interior space 106 of the chamber 102 thus allows conclusions to be drawn as to the gas pressure P2 of the process gas 304 in the first exterior space 120 of the chamber 102 and hence at the working site 306 of the apparatus 300 (Fig. 3).

[0106] In the second exterior space 126 of the chamber 102, which is adjacent to the second side 124 of the chamber 102, there is a gas pressure P3. The deflection A of the pressure diaphragm 122 from its rest position 130 is dependent on the pressure differential AP between the pressure Pl of the process gas 304 in the interior space 106 and the pressure P3 of the gas 128 in the second exterior space 126.

[0107] It should be noted that the pressure P 1 is the pressure established at the site of the opening 104 because of the gas flow rate F. As soon as the gas 304 leaves the supply conduit 338 (Fig.3), the gas molecules are distributed and fill the whole vacuum chamber 310, and a background pressure P3 is established. At the site of the opening 104, however, the pressure Pl is higher than P3, since the gas 304 has not yet been fully distributed there.

[0108] The gas pressure measuring device 100 is set up for positioning in the apparatus 300 (Fig. 3) in such a way that the opening 104 of the chamber 102 is at the working site 306 of the apparatus 300. With the aid of the gas pressure measuring device 100, the pressure P = Pl = P2 of the process gas 304 at the working site 306 of the apparatus 300 can thus be detected. In other words, the pressure P = Pl = P2 of the process gas 304 can be detected at the site of the apparatus 300 where the process gas 304 is activated by a particle beam 318 of the apparatus 300.

[0109] A size and / or a diameter D of the opening 104 of the chamber 102 (Fig. 1) is, for example, 100 pm or less, 50 pm or less, 30 pm or less, 10 pm or less and / or 5 pm or less. The choice of a very small opening 104 allows measurement of the pressure Pl of the process gas 304 with a high spatial resolution.

[0110] The gas pressure measuring device 100 also has a sensor unit 134 for detecting the deflection A of the pressure diaphragm 122, as can be seen in Fig. 1. The sensor unit 134 is disposed outside the chamber 102. The sensor unit 134 is disposed in particular in the second exterior space 126 of the chamber 102 that adjoins the pressure diaphragm 122. The sensor unit 134 is secured, for example, to the chamber 102 (for example the chamber wall 108), as illustrated by way of example in Fig. 1 by a mount 135.

[0111] The sensor unit 134 is set up, for example, to detect a distance B between a sensor surface 136 of the sensor unit 134 and a surface 138 of the pressure diaphragm 122 at its maximum deflection A. For example, the distance B is in the region of 100 pm or less, 50 pm or less, and / or 20 pm or less. In this case, the sensor unit 134 is set up to give distance sensor data SB (Fig. 8) as output (for example to send it to a control device 360). For example, the sensor unit 134 is a capacitive sensor unit set up for capacitative detection of the distance B to the surface 138 of the pressure diaphragm 122. In this case, the pressure diaphragm 122 includes an electrically conductive material, and a capacitance between the sensor surface 136 and the pressure diaphragm 122 is detected by the sensor unit 134 and converted to a distance B. As an alternative to a capacitive sensor unit, the sensor unit 134 in other examples may also be a confocal sensor unit, interferometric sensor unit and / or another type of sensor unit for detecting a distance B.

[0112] The sensor unit 134 may - instead of detecting a distance B between the sensor surface 136 and the surface 138 of the pressure diaphragm 122 - also be set up to detect a different physical quantity from which the extent of deflection A of the pressure diaphragm 122 can be concluded. If the sensor unit 134 is a capacitive sensor unit, it may also be set up to detect the capacitance between the sensor surface 136 and the pressure diaphragm 122 of the sensor unit 134 as the extent of deflection A. In this case, the sensor unit 134 is set up to give capacitive sensor data SK (Fig. 8) as output.

[0113] As shown in Fig. 1, the chamber 102 has, on the first side 118, for example, a flat outer surface 140 with the opening 104. The flat outer surface 140 is set up to completely cover the area of a gas nozzle 340 of the apparatus 300. In Fig. 4, it can be seen that an area R1 of the flat outer surface 140, for example, is larger than an area R2 which is completely covered by the gas nozzle 340 of the apparatus 300. Thus, the gas pressure measuring device 100 has, on the first side 118, a sufficiently extended surface area 140 to influence the outflow of the gas flow F flowing out of a gas nozzle 340 in a similar manner to a photomask 302. The gas pressure measuring device 100, in particular the chamber 102, is thus geometrically designed such that the influence of a photomask 302 on the gas flow is sufficiently reproduced.

[0114] Optionally, the gas pressure measuring device 100 may also have one or more temperature sensors 342, 344 for detecting a temperature Tl, T2 of the pressure diaphragm 122 and / or the sensor unit 134. The one or more temperature sensors 342, 344 can be used to calibrate a thermal drift in the pressure measurement.

[0115] Fig. 1 shows a first embodiment of the gas pressure measuring device 100. In the gas pressure measuring device 100, the first side 118 of the chamber 102 that has the opening 104 is arranged opposite the second side 124 of the chamber 102. In the example of Fig. 1, the first and second sides 118, 124, i.e. the first and second sections 110, 112 of the chamber wall 108, are arranged parallel to each other.

[0116] Fig. 2 shows a second embodiment of the gas pressure measuring device 200. In the gas pressure measuring device 200, the first side 218 of the chamber 202 that has the opening 204 is arranged at an angle (e.g. perpendicularly) to the second side 224 of the chamber 202 with the pressure diaphragm 222. This also means that the first and second sections of the chamber wall are arranged at an angle (e.g. perpendicularly) to one another. In this embodiment, the gas pressure measuring device 200 can be designed in a particularly space-saving manner. The reference numeral 230 indicates a rest position of the pressure diaphragm 222, and the reference numeral 232 indicates a deflected position of the pressure diaphragm 222. Furthermore, the reference numeral 234 in Fig. 2 indicates a sensor unit of similar design to the sensor unit 134 in Fig. 1.

[0117] Fig. 3 shows a schematic drawing of an apparatus 300 for particle beam-induced processing of a photomask 302.

[0118] The apparatus 300 comprises a housing 310 which is evacuated by a vacuum pump 312 to a pressure in the range of 102- 108mbar in order to create a process atmosphere 314 in the housing 310. The apparatus 300 additionally comprises a particle beam provision device 316, disposed in the vacuum housing 310, for provision of a focussed particle beam 118. The particle beam provision device 316 includes a particle source 320 and one or more beam-guiding and / or beamforming units 322, 324 that steer the particle beam 318 in the desired manner onto a surface 326 of the photomask 302. For example, the particle beam provision device 316 is an electron column set up to provide a focused electron beam 318. Moreover, the apparatus 300 comprises one or more detectors 328, for example for detection of secondary electrons.

[0119] The apparatus 300 also comprises a sample stage 330 for holding and positioning the photomask 302 to be processed. The sample stage 330 is actuatable in two or preferably in three spatial directions (arrow C). Moreover, the sample stage 330 may be mounted so as to be tiltable and rotatable in order to position the photomask 302. In particular, the sample stage 330 is mounted with vibration damping and is mechanically decoupled from the rest of the structure (not shown).

[0120] The apparatus 300 further comprises the at least one gas provision device 308 for providing the at least one process gas 304. The at least one gas provision device 308 is, for example, disposed partly outside the housing 310. The at least one gas provision device 308 has at least one reservoir vessel 332 and / or a gas generation device 334. The at least one gas provision device 308 additionally has a gas flow rate adjustment unit 336 for adjusting a gas flow rate F of the process gas 304. In particular, the gas flow rate adjustment unit 336 is set up to adjust at least one gas parameter G indicative of a gas flow rate of the process gas 304 provided.

[0121] In addition, the at least one gas provision device 308 has at least one feed conduit 338 and / or at least one feed duct 338 that leads into the housing 310 and opens into a nozzle 340 at its end. The nozzle 340 is, for example, an annular nozzle from which the process gas 304 exits in a ring shape and is supphed to the working site 306. Fig. 3 shows, as an example, such a ring nozzle in schematic cross section. Although not apparent in Fig. 3, the supply conduit 238' is also fluidi- cally connected to the reservoir vessel 332 and / or the gas generation device 334. In addition to the gas provision device 308 shown, further gas provision devices similar to the gas provision device 308 may be provided in order to feed further process gases to the photomask 302.

[0122] In the apparatus 300, an extraction unit (not shown) may additionally be provided in order to extract surplus process gas 304 from the process atmosphere 314, in particular from the surface 326 of the photomask 302. For this purpose, the suction unit comprises, for example, a further pump.

[0123] The apparatus 300 shown in Fig. 3 for particle beam-induced processing of the photomask 302 may be part of an arrangement 400, which additionally comprises a gas pressure measuring device 100, 200. The gas pressure measuring device 100, 200 may be any of the gas pressure measuring devices 100, 200 described above (Fig. 1, 2). The gas pressure measuring device 100, 200 is used for measuring a gas pressure P of the at least one process gas 304 at the working site 306 of the apparatus 300.

[0124] The gas pressure measuring device 100, 200 may be provided unconnected to the apparatus 300. For example, the gas pressure measuring device 100, 200 may be loaded into the apparatus 300 like a photomask 302 - but in place of a photomask 302 - i.e. positioned on the sample stage 330.

[0125] However, the gas pressure measuring device 100, 200 may also be secured mova- bly in the apparatus 300 in such a way that the gas pressure measuring device 100, 200 is movable from a parked position 402 (Fig. 3) into a working position 404 (Fig. 4) and back. In the working position 404 (Fig. 4), the opening 104, 204 of the chamber 102, 202 of the gas pressure measuring device 100, 200 is positioned at the working site 306 of the apparatus 300. In the parked position 402 (Fig. 3), the working site 306 of the apparatus 300 is free from the gas pressure measuring device 100, 200.

[0126] It should be noted that the particle beam 318 in Fig. 4 is only drawn to indicate the position of the sample stage 330 relative to the particle beam 318. In the working position 404 of the gas pressure measuring device 100, 200 shown in Fig. 4, in which the gas pressure P 1 is measured, only the process gas 304 is provided, but the particle beam 318 is not provided.

[0127] Fig. 3 shows a first example of movable securing of the gas pressure measuring device 100, 200 in the apparatus 300. In the example of Fig. 3, a supporting surface 346 of the sample stage 330 has a mask region 348 for positioning of the photomask 302, and an edge region 350 in which the gas pressure measuring device 100, 200 is secured to the supporting surface 346 of the sample stage 330. With the aid of the displaceable sample stage 330 (arrow C), the gas pressure measuring device 100, 200 can be moved from the parked position 402 (Fig. 3) into the working position (Fig. 4).

[0128] Fig. 5 shows a second example of movable securing of the gas pressure measuring device 100', 200' in the apparatus 300' of an arrangement 400'. In the second example, the gas pressure measuring device 100', 200' is secured to a mount 352 which is secured movably (e.g. pivotably, arrow E) to the sample stage 330'. In particular, the gas pressure measuring device 100', 200', with the aid of the mount 352, is movable (e.g. pivotable) from a parked position 402' into a working position 404'.

[0129] Figures 6 and 7 show two embodiments of gas provision devices 308', 308" of the apparatus 300 from Fig. 3.

[0130] The gas provision device 308' in a first embodiment in Fig. 6 comprises a reservoir vessel 354 with a cooled liquid reservoir 356, from which the process gas 304' evaporates. In addition, the gas flow rate adjustment unit 336' is set up, for example, to adjust a temperature T of the liquid 356 of the liquid reservoir, in order thus to adjust the gas flow rate F' of the process gas 304'.

[0131] The gas provision device 308" in a second embodiment in Fig. 7 comprises, for example, a pressurized gas vessel 358 for receiving the process gas 304". In addition, the gas flow rate adjustment unit 336" is set up to adjust a gas flow rate F" of the process gas 304" (for example also with the aid of one or more valves).

[0132] The arrangement 400 in Fig. 3 additionally includes a control device 360. Fig. 8 illustrates functional components of the control device 360.

[0133] The control device 360 has a first ascertainment device 362 and a second ascertainment device 362. The first ascertainment device 362 is set up to ascertain a pressure P, Pl of the process gas 304 in the chamber 102, 202 of the gas pressure measuring device 100, 200 based on the detected deflection A of the pressure diaphragm 122, 222. In particular, the first ascertainment device 362 is set up to receive sensor data SK, SB from the sensor unit 134, 234 in relation to the deflection A of the pressure diaphragm 122, 222. In addition, the first ascertainment device 362 is set up to ascertain pressure values Pl of the process gas 304 for different values of the at least one gas parameter G indicative of the gas flow rate F.

[0134] The second ascertainment device 362 is set up to ascertain a calibration table K based on the pressure values Pl depending on the gas parameter G indicative of the gas flow rate F. The calibration table K has the different values of the at least one gas parameter G of the process gas 304, and the pressure values Pl ascertained as the pressure values of the process gas 304 at the working site 306 of the apparatus 300 assigned to the different values of the at least one gas parameter G.

[0135] The control device 360 can also be set up to ascertain one calibration table K for each of several process gases 304.

[0136] There follows a description, with reference to Fig. 9, of a method of calibrating a gas pressure Pl of a process gas 304 at a working site 306 of an apparatus 300 for particle beam-induced processing of a photomask 302 for microlithography. In a first step S101 of the method, a gas pressure measuring device 100, 200 (Fig. 1, 2) is disposed in the apparatus 300 such that an opening 104, 204 of a chamber 102, 202 of the gas pressure measuring device 100, 200 is at the working site 306 of the apparatus 300.

[0137] In a second step S102 of the method, a process gas 304 is fed to the working site 306 (i.e. also into the first exterior space 120 of the chamber 102, 202). The process gas 304 supplied penetrates through the opening 104, 204 into the chamber 102, 202 of the gas pressure measuring device 100, 200. In step S102, the process gas 304 is supplied, in particular, successively with different values of at least one gas parameter G indicative of a gas flow rate F of the process gas 304. The gas parameter G indicative of the gas flow rate F of the process gas 304 is, for example, an adjustable temperature T of a liquid reservoir 356 of the gas provision device 308' in Fig. 6 or an adjustable (e.g. directly adjustable) gas flow rate F" of the gas provision device 308" in Fig. 7.

[0138] In a third step S103 of the method, a pressure Pl of the process gas 304 is ascertained using the gas pressure measuring device 100, 200 depending on the different values of the at least one gas parameter G.

[0139] In a fourth step S 104 of the method, a calibration table K that has the pressure values Pl ascertained as pressure values of the process gas 304 at the working site 306 of the apparatus 300 assigned to the different values of the at least one gas parameter G is ascertained.

[0140] The calibration table K ascertained can be used in the processing of a photomask 302 with the apparatus 300. The calibration table K ascertained can be used in particular to establish a gas pressure P, Pl of a process gas 304 at the working site 306 of the apparatus 300 by adjusting the gas parameter G indicative of the gas flow rate F. In other words, the calibration table K ascertained can be used to adjust the gas parameter indicative of the gas flow rate F (e.g. a temperature T and / or a gas flow rate F") in a gas provision device 308, 308', 308" of the apparatus 300 for the process gas 304 in question such that it corresponds to the pressure P, Pl of the process gas 304 at the working site 306 according to the calibration table K.

[0141] There follows a description, with reference to Fig. 10, of a method of particle beam-induced processing of a photomask 302 for microlithography.

[0142] In a first step S201 of the method, at least one calibration table K for at least one process gas 304 is provided. The calibration table K has pressure values P 1 of the process gas 304 at a working site 306 of the apparatus 300 assigned to different values of at least one gas parameter G of the process gas 304 which is indicative of a gas flow rate F.

[0143] Step S201 is executed, for example, by executing steps S 101 to S104 of the abovedescribed calibration method according to Fig. 9 using the apparatus 300.

[0144] Alternatively, the at least one calibration table K is ascertained, for example, by executing steps S 101 to S104 of the above-described calibration method according to Fig. 9 using a first apparatus (not shown) for particle beam-induced processing of a photomask for microlithography. The subsequent steps S202 to S204 of the method of particle beam-induced processing according to Fig. 10 can then be executed using a second apparatus 300 for particle beam-induced processing of a photomask 302 for microlithography, for example using the apparatus 300 in Fig. 3. The first apparatus is, in particular, of similar configuration to the second apparatus 300 (Fig. 3).

[0145] In a second step S202 of the method, a photomask 302 is positioned in the apparatus 300 such that a portion of the photomask 302 to be processed is at the working site 306.

[0146] In a third step S203 of the method, a predetermined pressure value P, Pl of the at least one process gas 304 is established at the working site 306. The predetermined pressure value P, P 1 of the at least one process gas 304 at the working site 306 is established in particular by adjusting the at least one parameter G, T, F" indicative of the gas flow rate F, F', F" of the at least one process gas 304 based on the at least one calibration table K provided. In a fourth step S204 of the method, the photomask 302 is processed in a particle beam-induced manner by means of the at least one process gas 304 and a particle beam 318.

[0147] There follows a description, with reference to Fig. 11, of a method of calibrating a gas pressure measurement device 100, 200.

[0148] In a first step S301 of the method, a calibration gas (e.g. the process gas 304) is fed at a predetermined pressure P2 to the opening 104, 204 of the chamber 102, 202 of the gas pressure measuring device 100, 200.

[0149] In a second step S302 of the method, the calibration gas (e.g. the process gas 304) penetrates through the opening 104, 204 into the chamber 102, 202. The calibration gas (e.g. the process gas 304) penetrates through the opening 104, 204 into the chamber 102, 202 until a pressure equilibrium Pl = P2 (Fig. 1) has been established.

[0150] In a third step S303 of the method, a pressure Pl of the calibration gas (e.g. the process gas 304) is determined in the chamber 102, 202 based on the detected deflection A of the pressure diaphragm 122, 222 of the gas pressure measuring device 100, 200.

[0151] The method according to Fig. 11 can be used to calibrate the gas pressure measuring device 100, 200 even prior to use. In particular, it is possible to calibrate the assignment of a pressure value P 1 to a degree of deflection A of the pressure diaphragm 122, 222. For example, it is possible to check whether a gas pressure measuring device 100, 200 still fulfils the required accuracy after a predetermined period of utilization.

[0152] Although the present invention has been described using working examples, it is modifiable in a variety of ways. LIST OF REFERENCE SYMBOLS

[0153] 100, 100' gas pressure measuring device

[0154] 102 chamber

[0155] 104 opening

[0156] 106 interior space

[0157] 108 chamber wall

[0158] 110 ■ 116 section

[0159] 118 side

[0160] 120 exterior space

[0161] 122 pressure diaphragm

[0162] 124 side

[0163] 126 exterior space

[0164] 128 gas

[0165] 130 rest position

[0166] 132 pose

[0167] 134 sensor unit

[0168] 135 mount

[0169] 136 sensor surface

[0170] 138 surface

[0171] 140 outer surface

[0172] 200, 200' gas pressure measuring device

[0173] 202 chamber

[0174] 204 opening

[0175] 218 side

[0176] 222 pressure diaphragm

[0177] 224 side

[0178] 230 rest position

[0179] 232 position

[0180] 234 sensor unit

[0181] 238, 238' supply conduit

[0182] 300, 300' apparatus

[0183] 302 photomask

[0184] 304, 304', 304" process gas

[0185] 306 working site 308, 308', 308" gas provision device

[0186] 310 housing

[0187] 312 vacuum pump

[0188] 314 process atmosphere

[0189] 316 particle beam provision device

[0190] 318 particle beam

[0191] 320 particle source

[0192] 322, 324 unit

[0193] 326 surface

[0194] 328 detector

[0195] 330, 330' sample stage

[0196] 332 reservoir vessel

[0197] 334 gas generation device

[0198] 336, 336', 336" gas flow rate adjustment unit

[0199] 338 supply conduit

[0200] 340 nozzle

[0201] 342, 344 temperature sensor

[0202] 346 supporting surface

[0203] 348 mask region

[0204] 350 edge region

[0205] 352 mount

[0206] 354 reservoir vessel

[0207] 356 liquid reservoir

[0208] 358 compressed gas vessel

[0209] 360 control device

[0210] 362 ascertainment device

[0211] 400, 400' arrangement

[0212] 402, 402' parked position

[0213] 404, 404' working position

[0214] A deflection

[0215] B distance

[0216] C arrow

[0217] D diameter

[0218] E arrow F F' F" gas flow rate

[0219] G parameter

[0220] K calibration table

[0221] P, Pl -P3 pressure AP pressure differential

[0222] Rl, R2 area

[0223] SB sensor data

[0224] SK sensor data

[0225] S101-S104 method steps S201-S204 method steps

[0226] S301-S303 method steps temperature

Claims

CLAIMS1. Gas pressure measuring device (100) for measuring a pressure (P, Pl) of a process gas (304) at a working site (306) of an apparatus (300) for particle beam- induced processing of a photomask (302) for microlithography, comprising: a chamber (102) with an opening (104) on a first side (118) for receiving the process gas (304) and a pressure diaphragm (122) on a second side (124), and a sensor unit (134) for detecting a deflection (A) of the pressure diaphragm (122) for ascertaining a pressure (Pl) of the process gas (304) in the chamber (102) as a pressure (P) of the process gas (304) at the working site (306), wherein the gas pressure measuring device (100) is set up to be positioned in the apparatus (300) such that its opening (104) is at the working site (306) of the apparatus (300).

2. Gas pressure measuring device according to Claim 1, wherein the pressure diaphragm (122) forms a section (112) of a wall (108) of the chamber (102) and the sensor unit (134) is disposed outside the chamber (102), the sensor unit (134) is set up to detect a distance (B) between a sensor surface (136) of the sensor unit (134) and a surface (138) of the pressure diaphragm (122) at its maximum deflection (A), and / or the pressure diaphragm (122) includes an electrically conductive material and the sensor unit (134) is set up to detect a capacitance between the sensor surface (136) of the sensor unit (134) and the pressure diaphragm (122).

3. Gas pressure measuring device according to Claim 1 or 2, wherein the pressure diaphragm (122) includes an electrically conductive material, and the sensor unit (134) is a capacitive sensor unit (134).

4. Gas pressure measuring device according to any of Claims 1 to 3, wherein a size and / or a diameter (D) of the opening (104) of the chamber (102) is 100 pm or less, 50 pm or less, 30 pm or less, 10 pm or less and / or 5 pm or less.

5. Gas pressure measuring device according to any of Claims 1 to 4, wherein the gas pressure measuring device (100) is set up for positioning within theapparatus (300) such that the first side (118) of the chamber (102) is opposite a gas nozzle (340) of the apparatus (300).

6. Gas pressure measuring device according to Claim 5, wherein the chamber (102) on the first side (118) has a flat outer surface (140) with the opening (104), and the flat outer surface (140) is set up to completely cover the area of the gas nozzle (340).

7. Gas pressure measuring device according to any of Claims 1 to 6, comprising at least one temperature sensor (342, 344) for detecting a temperature (Tl, T2) of the pressure diaphragm (122) and / or the sensor unit (134).

8. Arrangement (400) comprising an apparatus (300) for particle beam-induced processing of a photomask (302) for microlithography and a gas pressure measuring device (100) according to any of Claims 1 to 7.

9. Arrangement according to Claim 8, wherein the gas pressure measuring device (100) is secured so as to be movable within the apparatus (300) for particle beam-induced processing such that the gas pressure measuring device (100) is movable from a parked position (402) to a working position (404) and back, and wherein, in the working position (404), the opening (104) of the chamber (102) of the gas pressure measuring device (100) is disposed at the working site (306) of the apparatus (300).

10. Arrangement according to Claim 8 or 9, wherein the apparatus (300) for particle beam -induced processing comprises at least one gas provision device (308) for providing at least one process gas (304) at the working site (306), the at least one gas provision device (308) has a gas flow rate adjustment unit (336) for adjusting at least one gas parameter (G) indicative of a gas flow rate (F) of the process gas (304) provided, and the arrangement (400) has a control device (360) designed for the purpose of, for a respective process gas (304): ascertaining a pressure (Pl) of the process gas (304) in the chamber(A) of the pressure diaphragm (122) of the gas pressure measuring device (100), by ascertaining pressure values (Pl) of the process gas (304) for different values of the at least one gas parameter (G) indicative of the gas flow rate (F), and ascertaining a calibration table (K) that has the ascertained pressure values (Pl) as pressure values (P) of the process gas (304) at the working site (306) of the apparatus (300) assigned to the different values of the at least one gas parameter (G) of the process gas (304).

11. Method of calibrating a gas pressure (P, Pl) of a process gas (304) at a working site (306) of an apparatus (300) for particle beam-induced processing of a photomask (302) for microlithography, comprising the steps of: al) positioning (S101) a gas pressure measuring device (100), in particular a gas pressure measuring device (100) according to any of Claims 1 to 7, in the apparatus (300) such that an opening (104) of a chamber (102) of the gas pressure measuring device (100) is present at the working site (306) of the apparatus (300), bl) feeding (S102) a process gas (304) to the working site (306) and causing the process gas (304) to penetrate through the opening (104) into the chamber (102) of the gas pressure measuring device (100), where the process gas (304) is fed in successively with different values of at least one gas parameter (G) indicative of a gas flow rate (F) of the process gas (304); cl) ascertaining (S103) a pressure (Pl) of the process gas (304) using the gas pressure measuring device (100) depending on the different values of the at least one gas parameter (G), and dl) ascertaining (S104) a calibration table (K) that has the ascertained pressure values (Pl) as pressure values (P) of the process gas (304) at the working site (306) of the apparatus (300) assigned to the different values of the at least one gas parameter (G).

12. Method of particle beam -induced processing of a photomask (302) for microlithography, comprising the steps of: a2) providing (S201) at least one calibration table (K) for at least one process gas (304), where the calibration table (K) has pressure values (P) of the process gas (304) at a working site (306) of the apparatus (300) assigned to differentvalues of at least one gas parameter (G) of the process gas (304) which is indicative of a gas flow rate (F), b2) positioning (S202) a photomask (302) in the apparatus (300) such that a portion of the photomask (302) to be processed is at the working site (306), and c2) establishing (S203) a predetermined pressure value (P) of the at least one process gas (304) at the working site (306) by adjusting the at least one parameter (G) indicative of the gas flow rate (F) of the at least one process gas (304) based on the at least one calibration table (K) provided, and d2) particle beam-induced processing (S204) of the photomask (302) using the at least one process gas (304) and a particle beam (318).

13. Method according to Claim 12, wherein the at least one calibration table (K) is determined and provided on the basis of the method according to Claim 11.

14. Method according to Claim 12 or 13, wherein the at least one calibration table (K) based on the method according to Claim 11 is ascertained by means of a first apparatus for particle beam-induced processing of a photomask (302) for microlithography, and steps b2) to d2) are performed using a second apparatus (300), different from the first apparatus, for particle beam-induced processing of a photomask (302) for microlithography.

15. Method of calibrating a gas pressure measuring device (100) according to any of Claims 1 to 7, comprising the steps of: feeding (S301) a calibration gas (304) at a predetermined pressure (P2) to the opening (104) of the chamber (102) of the gas pressure measuring device (100), causing (S302) the calibration gas (304) to penetrate through the opening (104) into the chamber (102), and ascertaining (S303) a pressure (Pl) of the calibration gas (304) in the chamber (102) based on the detected deflection (A) of the pressure diaphragm (122) of the gas pressure measuring device (100).

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