Methods and devices for adjusting a sidewall angle of a pattern element and for examining a defect in a photolithographic mask

Abstract

Method (2800) for setting at least one side wall angle (170, 670, 1970, 2470, 2770, 2780) of at least one pattern element (120, 220, 230, 250, 260, 280, 290) of a photolithographic mask (150, 200, 700), the method comprising the steps: a. Providing at least one precursor gas; b. Providing at least one massive particle beam (910, 1215, 1515, 1930, 2120) that excites a local chemical reaction of the at least one precursor gas; c. Changing at least one parameter of the particle beam (910, 1215, 1515, 1930, 2120) and / or a process parameter during the local chemical reaction to adjust the at least one sidewall angle (170, 670, 1970, 2470, 2770, 2780) of the at least one pattern element (120, 220, 230, 250, 260, 280, 290); and d. Changing the size of a repair shape (2620) in one dimension from the beginning to the end of the local chemical reaction by at least 5% relative to a process resolution limit in one dimension.

Description

[0001] The present invention relates to a method and a device for adjusting a sidewall angle of a pattern element of a photolithographic mask. Furthermore, the present invention relates to a method and a device for inspecting a defect in a photolithographic mask. 2. State of the art

[0002] As a result of the growing integration density in the semiconductor industry, photolithographic masks must image increasingly smaller structures on wafers. One way to address this trend is to use photolithographic masks whose actinic wavelength is shifted to ever shorter wavelengths. Currently, ArF (argon fluoride) excimer lasers, which emit at a wavelength of approximately 193 nm, are frequently used as light sources in photolithography.

[0003] Lithography systems are currently under development that use electromagnetic radiation in the EUV (extreme ultraviolet) wavelength range (preferably in the range from 10 nm to 15 nm). These EUV lithography systems are based on a completely new beam delivery concept that utilizes reflective optical elements, as no materials are currently available that are optically transparent in the specified EUV range. The technological challenges in developing EUV systems are enormous, and enormous development efforts are necessary to bring these systems to industrial readiness.

[0004] Photolithographic masks, exposure masks, photomasks, or simply masks, play a significant role in imaging ever smaller structures in the photoresist arranged on a wafer. With each further increase in integration density, it becomes increasingly important to reduce the minimum feature size of the exposure masks. The manufacturing process for photolithographic masks is therefore becoming increasingly complex, time-consuming, and ultimately expensive. Due to the tiny feature sizes of the pattern elements, errors in mask manufacturing cannot be ruled out. These must be repaired whenever possible.

[0005] The described problem occurs to a greater extent in nanoimprint lithography. In nanoimprint lithography, the structure is transferred from the nanostructured stamp to a positive applied to a substrate at a 1:1 ratio. Therefore, this lithography technique is subject to stricter requirements regarding compliance with feature sizes and sidewall angles. These stricter requirements also apply to the repair of defects in nanoimprint stamps.

[0006] Due to the new beam guidance concept, which uses exclusively reflective optical elements, including the EUV photomask, the latter cannot be exposed perpendicularly. Rather, in current EUV mask exposure systems, the EUV radiation impinges on the patterned surface of the EUV mask at an angle of 5° to 6° from the normal. This oblique incidence of light leads to various difficulties. Some are described in the exemplary documents, and corresponding solutions are proposed therein: US 5,485,497 A, US 7,198,872 B2, and US 9,285,672 B2.

[0007] The repair of mask defects is currently often performed using electron beam-induced local deposition and / or etching processes. Due to the decreasing feature sizes of the structure or pattern elements, the requirements for the repair processes are becoming increasingly challenging. For this reason, in addition to the previously known characterization parameters of photolithographic masks, such as the critical dimension (CD) and / or the edge position, other descriptive parameters are becoming increasingly important. In particular, the edge steepness or the sidewall angle of a structure or pattern element are worth mentioning here.

[0008] As described in DE 10 2019 201 468 A1, when repairing defects in photolithographic masks, the current goal is to achieve a sidewall angle (SWA) or edge steepness of a repaired pattern element that is as close as possible to the reference structure specified by the design. This is typically a sidewall angle of 90°. This is especially true for the correction of photomasks for the EUV wavelength range.

[0009] On the other hand, in the article "Impact of EUV mask absorber sidewall angle on patterning robustness," Proc. SPIE, Vol. 10583, Extreme Ultraviolet (EUV) Lithography IX, 1058314 (19 March 2018), https: / / doi.org / 10.11117 / 12.2296865, the authors LS Mervin III et al. describe simulations that suggest that a sidewall angle deviating from 90° can, under certain circumstances, have favorable properties on the imaging behavior of EUV masks.

[0010] Against this background, the present invention is based on the problem of specifying methods and devices which make it possible to improve the repair of photolithographic masks. 3. Summary of the invention

[0011] According to one embodiment of the present invention, this problem is solved by a method according to claim 1 and a device according to claim 17. In a further embodiment, this problem is solved by a method according to claim 10 and a device according to claim 19.

[0012] In one embodiment, the method for adjusting at least one sidewall angle of at least one pattern element of a photolithographic mask comprises the steps of: (a) providing at least one precursor gas; (b) providing at least one massed particle beam configured to excite a local chemical reaction of the at least one precursor gas; (c) changing at least one parameter of the particle beam and / or a process parameter during the local chemical reaction to adjust the at least one sidewall angle of the at least one pattern element; and (d) changing a size of a repair shape in one dimension from the beginning to the end of the local chemical reaction by at least 5% relative to a process resolution limit in one dimension.

[0013] The method according to the invention enables the targeted adjustment of a sidewall angle of a pattern element of a photolithographic mask. This angle can be within an angular range deviating from 90°. This opens up an additional degree of freedom that can be used to improve the imaging properties of photolithographic masks. This degree of freedom allows, for example, the process window within which a photomask with a defined sidewall angle can be operated to be enlarged. Furthermore, the additional degree of freedom can be used to compensate for other weak points or imperfect or imperfect properties of the mask. The ability to control the edge steepness or the sidewall angle thus allows the optical properties of the photolithographic mask to be improved.

[0014] When repairing embossing stamps (templates) and / or substrates of nanoimprint lithography (NIL), the method according to the invention can be used to meet the stringent requirements regarding edge steepness.

[0015] In this application, the terms edge steepness and sidewall angle are used as synonyms.

[0016] The at least one precursor gas may comprise at least one etching gas and the local chemical reaction may comprise an etching reaction, or the at least one precursor gas may comprise at least one deposition gas and the local chemical reaction may comprise a deposition reaction.

[0017] The at least one mass-carrying particle beam can excite the local chemical reaction at the location of the sidewall angle to be adjusted. The at least one mass-carrying particle beam can excite the local chemical reaction at the location of a defect in the photolithographic mask.

[0018] A mass-bearing particle beam, such as an electron beam or an ion beam, can be focused to a spot diameter in the range of a few nanometers. This enables the execution of a chemical reaction whose reaction area is tightly confined. For example, the diameter of the local chemical reaction can be limited to a small multiple, such as two to five times the spot diameter of the particle beam. A process resolution limit of a local chemical reaction in one dimension can thus be in the range of 1 nm to 30 nm, preferably 2 nm to 20 nm, more preferably 2 nm to 15 nm, and most preferably 2 nm to 10 nm.

[0019] The adjustment of at least one sidewall angle can be performed during a defect repair of the photolithographic mask.

[0020] The angle of a sidewall or the edge steepness of a pattern element of a mask that has an angle of substantially 90° does not represent a defect in the mask, but rather has exactly the value specified by the design. The method according to the invention enables the targeted modification of the angle of a sidewall of a pattern element or its setting to a specific value other than 90° in order to achieve one or more of the advantages described above, for example, an enlargement of the process window. Furthermore, a weak point of the photomask can be compensated for by a targeted adjustment of one or more sidewall angles of one or more pattern elements. A weak point of a photolithographic mask is a parameter that still lies within a specified numerical range, but approaches a range limit.

[0021] Typically, however, the sidewall angle of a pattern element is adjusted in a defined manner during a photomask repair process. Common defects in photolithographic masks are dark defects caused by excess material, such as excess absorber material. The excess material is often removed from the mask by performing an EBIE (electron beam induced etching) process. During the removal of the excess material, the angle of the newly formed sidewall of the pattern element is adjusted to a desired or specified value.

[0022] A defect in the absence of material is called a white defect if the missing material is absorbing material. This defect is corrected by depositing absorbing material, such as chromium or tantalum nitride, for example, in an EBID (electron beam induced deposition) process. During the EBID process, care is taken to ensure that the newly formed sidewall has a sidewall angle within a specified range.

[0023] The method according to the invention can, of course, also be used to adjust a sidewall angle of a phase-shifting element of a phase-shifting mask. Furthermore, the method according to the invention can, of course, also be used to adjust a sidewall angle of an element of a NIL template.

[0024] The term “essentially” here – as elsewhere in the description – means a specification of a measured quantity within the usual measurement errors if state-of-the-art measuring instruments are used to determine the measured quantity.

[0025] Changing the at least one parameter of the at least one particle beam may comprise at least changing one element from the group: - a centrosymmetric adjustment of at least one condenser diaphragm of an imaging system of at least one particle beam source with respect to an optical axis of the mass-bearing particle beam, - a non-circular setting of at least one aperture of the imaging system of the at least one particle beam source, - an adjustment of the imaging system of the at least one particle beam source for tilting the massed particle beam with respect to a perpendicular to the patterned surface of the photolithographic mask, - an adjustment of a deflection system for tilting the massed particle beam with respect to the normal to the patterned surface of the photolithographic mask, and - an adjustment of a beam profile of the massive particle beam during the local chemical reaction.

[0026] In the prior art, a set of parameters characterizing the mass-carrying particle beam is defined at the beginning of a photolithographic mask processing process, and these parameters are used to perform the processing, i.e., adjusting a sidewall angle and / or repairing a defect. Typically, the parameters of the system imaging the mass-carrying partial beam are selected such that the particle beam traverses the optical axis of the imaging system as precisely as possible. This results in an optical image of the particle beam source that exhibits essentially no aberration or only a low aberration component.

[0027] However, the inventors have recognized that it can be advantageous to deliberately guide the particle beam in a direction deviating from the optical axis of the imaging system of the particle beam source if the mass-bearing particle beam is used to initiate a local chemical reaction. It can also be advantageous to select a beam profile that deviates from circular symmetry. These settings increase the aberrations of the generated particle beam. However, these negative effects on the imaging properties of the particle beam are accepted when it is used to stimulate a local chemical reaction, since the particle beam is used merely as an energy supplier. It is even possible that a distorted particle beam generates an energy dose distribution that accelerates the local chemical reaction compared to a largely aberration-free mass-bearing particle beam.

[0028] By changing one or more parameters of the imaging system of the particle beam source during the execution of a local chemical reaction as described above, an additional degree of freedom is opened up, which allows, in addition to repairing a defect, to adapt the edge steepness of a pattern element of a photomask and / or an element of a NIL template to a given angle.

[0029] Condenser diaphragms of current scanning electron microscopes (SEMs) typically range in diameter from 10 µm to 60 µm. A non-centrosymmetric electron beam alignment can be referenced to the center of the circular condenser diaphragm. The two extreme values ​​of the alignment are: the electron beam passes perpendicularly through the center of the condenser diaphragm and the beam passes perpendicularly along one edge of the condenser diaphragm.

[0030] The setting of the at least one non-circular aperture may comprise an eccentricity ε in the range of 0 < ε 0.1, preferably 0 < ε < 0.2, more preferably 0 < ε < 0.5, and most preferably 0 < ε < 0.8.

[0031] Adjusting the imaging system of the at least one particle beam can comprise: changing an angle of incidence of the massed particle beam on a surface of the at least one pattern element in a range from 89° to 91°, preferably from 80° to 93°, more preferably from 70° to 100°, and most preferably from 60° to 120°. Changing within a range can be understood as applying a particle beam with an angle of incidence with at least one numerical value that is approximately at the upper limit of the range (e.g., approximately 93° for the interval 80° to 93°) and / or applying a particle beam with an angle of incidence whose numerical value is approximately at the lower limit of the range (e.g., approximately 80° again for the interval 80° to 93°).

[0032] Changing the beam profile setting may include changing the beam profile setting from a round to an asymmetric beam profile. The asymmetric beam profile may include an elliptical beam profile. The eccentricity ε of an elliptical beam profile may range from 0 ≤ ε < 0.1, preferably 0 ≤ ε < 0.2, more preferably 0 ≤ ε < 0.5, and most preferably 0 ≤ ε < 0.8.

[0033] Changing the at least one process parameter may include at least one element from the group: - dividing a repair form into at least two partial repair forms for processing the at least two partial repair forms with different process parameters, - Changing at least one parameter from the group: a frame refresh time, a dwell time, a distance between adjacent grid points of the mass-carrying particle beam (line step), and an electrical acceleration voltage of the at least one mass-carrying particle beam during the local chemical reaction, - Changing a size of the repair shape during the local chemical reaction, and - Changing a position of the repair mold during the local chemical reaction.

[0034] Currently, defects in photolithographic masks are corrected by determining a set of parameters for the defect repair process. Using this defined set of process parameters, the defect is then removed by scanning the mass-laden particle beam over the defect while providing an appropriate precursor gas, or a sidewall of a pattern element is generated at a specified angle. However, the repair of many defects is significantly more promising if at least one of the process parameters is adapted locally and / or temporally to the specific defect to be repaired during the defect repair process.

[0035] A repair shape describes the projection of a defect to be repaired onto its base surface. Each pixel of the base surface is assigned an energy dose to be deposited, which represents the duration of the local chemical reaction at the corresponding pixel and corresponds to the extent of the defect at that pixel location.

[0036] By dividing a repair shape into two or more partial repair shapes and assigning each partial repair shape a separate set of process parameters, the repair of the defect can be improved and, by means of the additional degree(s) of freedom, an edge steepness formed during the defect repair can be shaped with an angle within a specified interval.

[0037] The repetition time depends heavily on the specific process being performed. One important factor, for example, is the size of the repair mold. Furthermore, the repetition time should be selected so that gas coverage of the repair mold is restored within the repetition time. Taking these constraints into account, the repetition time at the beginning of the local chemical reaction can be in the range of 10 -8 s to 10 -6 s and at the end of which a time duration in the range of 10 -7 s to 10 -5 s have.

[0038] The residence time at the beginning of the local chemical reaction can be in the range of 10 -9 s to 10 -7 s and at the end of which a time duration in the range of 10 -7 s to 10 -6 s have.

[0039] The distance between adjacent grid points of the massed particle beam can range from 40 nm to 20 nm at the beginning of the local chemical reaction and from 10 nm to 1 nm at its end.

[0040] The acceleration voltage of the massive particle beam can range from 5 keV to 1 keV at the beginning of the local chemical reaction and from 1 keV to 0.1 keV at the end. This acceleration voltage range is particularly applicable to a massive particle beam in the form of an electron beam. Generally, higher acceleration voltages are required for more massive particles, such as ions.

[0041] By adjusting one or more of the last four process parameters, additional degrees of freedom are obtained, which can be used to improve a defect repair and to adjust the edge steepness of one or more edges or side walls generated during the defect repair within a given angular range.

[0042] Furthermore, the provision of the at least one precursor gas can be adapted to the change in one or more process parameters. Providing the at least one precursor gas can include adjusting a gas flow rate, a temperature, and / or a composition of the at least one precursor gas.

[0043] The size of the repair shape may change in one dimension from the beginning to the end of the local chemical reaction by at least 5%, preferably by at least 30%, more preferably by at least 50%, and most preferably by at least 100% relative to a process resolution limit in one dimension.

[0044] By changing a repair shape in one dimension over time, it is possible to adjust the edge steepness of two side walls generated on both sides of the repair shape in a defined manner.

[0045] The position of an edge of the repair shape can change from the beginning to the end of the local chemical reaction by at least 5%, preferably by at least 30%, more preferably by at least 50%, and most preferably by at least 100% relative to a process resolution limit in one dimension.

[0046] Shifting the repair shape in one direction while performing a local chemical reaction allows adjusting an edge steepness in the direction of the shifted repair shape.

[0047] Changing at least one parameter of the particle beam and / or a process parameter during the local chemical reaction can adjust the at least one sidewall angle within a range of 85° to 95°, preferably from 80° to 100°, more preferably from 75° to 105°, and most preferably from 70° to 110°.

[0048] The method according to the invention may further comprise the steps of: (a) interrupting the local chemical reaction; and (b) examining a defect residue of the at least one defect and / or a sidewall generated during the local chemical reaction.

[0049] Furthermore, the method according to the invention can comprise the steps: (c) changing at least one parameter of the particle beam and / or a process parameter that has not been changed so far during the local chemical reaction, if the defect residue under investigation and / or the sidewall generated so require; and (d) continuing the local chemical reaction with the at least one changed parameter or continuing the local chemical reaction with the unchanged parameters if the defect residue under investigation and / or the sidewall generated so do not require.

[0050] Whether a change to one or more previously unchanged parameters is necessary is determined based on the previously generated edge steepness. A change is necessary if the previously generated edge steepness lies outside a specified angle range.

[0051] In the method defined in this application, one or more parameters are changed during the execution of a local chemical reaction. The described method can also be interrupted during its execution, and the remaining defect or the created sidewall can be examined. If the examination results show that the required edge steepness cannot be achieved with the varied parameter(s), one or more of the parameters that have not been changed in the previous course of the repair process can be changed, and the local chemical reaction is continued with the additionally changed parameters. It is possible to change the parameters varied in the previous repair process or to keep them constant.

[0052] In a second embodiment, the method for examining at least one defect of a photolithographic mask with at least one massed particle beam comprises the steps of: (a) providing at least one massed particle beam; and (b) changing an average angle of incidence of the massed particle beam on the at least one defect during the examination of the at least one defect.

[0053] Typically, a massed particle beam impinges perpendicularly on an object to be examined, for example, on a defect in a photolithographic mask. With a small working distance between the photolithographic mask and the part of the particle-optical system facing the mask, these two components can essentially only be aligned parallel to each other, whereby the particle beam impinges essentially perpendicularly on the photolithographic mask. As already explained above, a massed particle beam can be focused to a spot diameter in the range of a few nanometers to the sub-nanometer range. This results in a very high lateral resolution. However, its resolution in the beam direction is significantly lower. When examining a three-dimensional (3D) object with a massed particle beam, its height resolution suffers.Therefore, a 3D object created from the measurement data, such as an image of a defect, is subject to considerable uncertainty. This uncertainty in a 3D image of a defect translates, for example, into a large error interval for the parameters of a repair shape determined from the examinations.

[0054] This uncertainty can be significantly reduced by scanning the defect with the massed particle beam at different angles. This allows a precise 3D contour of the defect under investigation to be determined.

[0055] Typically, a particle beam scans a scan area of ​​a photolithographic mask or defect by scanning the particle beam line by line across the scan area. During the scanning of a line, the angle of incidence of the particle beam on the sample surface changes slightly. This change in the angle of incidence of the particle beam during a line scan, or generally during the scanning of a scan area, does not refer to the change in the angle of incidence on the surface of a photolithographic mask specified above under point (b). To distinguish the change in the angle of incidence defined above from the change in the angle of incidence during a line scan, the term "mean angle of incidence" is introduced. This describes the mean angle at which a particle beam impinges on a sample during a line scan.For example, the mean angle of incidence can be defined as the arithmetic mean of all angles of incidence of a line scan or, in general, of a scan area of ​​the particle beam.

[0056] The at least one defect may include at least one element from the group: - missing material of a pattern element, - excess material of a pattern element, - missing material of a substrate of the photolithographic mask, - excess material of the substrate of the photolithographic mask, - missing material of an element on a NIL substrate and / or a NIL template, - excess material of an element on a NIL substrate and / or a NIL template - a sidewall angle outside a specified range, - a radius of curvature of a side wall of the at least one pattern element to its surface, which is outside a predetermined range, and - a radius of curvature of the side wall of the at least one pattern element to the substrate of the photolithographic mask which is outside a predetermined range.

[0057] Changing the angle of incidence of the at least one mass-carrying particle beam may comprise: deflecting the mass-carrying particle beam in an electric field and / or in a magnetic field.

[0058] The easiest way to change the angle of incidence of a mass-carrying particle beam on a defect is to rotate the mask containing the defect about an axis perpendicular to the normal of the patterned side of the photomask. However, this embodiment often encounters the difficulty that the distance between a beam exit point of an imaging system of a particle beam source of the mass-carrying particle beam and the patterned surface of the mask is often so small that tilting the mask relative to the beam direction of the particle beam is only possible to a limited extent. For the same reason, tilting the imaging system of the particle beam source relative to the patterned surface of a photomask is also often only possible to a limited extent.

[0059] By forming an electric and / or a magnetic field between the beam exit of the mass-carrying particle beam from the imaging system and the mask and / or in the part of the imaging system adjacent to the beam exit, the spatial constraints can be largely avoided and the mass-carrying particle beam can be deflected by a defined angle relative to the optical axis of the imaging system of the particle beam.

[0060] The method for examining at least one defect may further comprise the step of determining a three-dimensional contour of the at least one defect from the measurement data obtained during the examination.

[0061] As explained above, scanning a defect at different angles increases its spatial resolution in the z-direction or in the beam direction. This makes it possible to determine a 3D contour of a defect scanned with a massed sub-beam at different angles with great precision.

[0062] The method for examining at least one defect may further comprise the step of determining parameters of a repair form for the at least one defect examined.

[0063] Based on a parameterized repair shape, i.e., a repair shape whose parameters are defined, a repair device can repair a defect. However, it is also possible for a repair shape to define the setting of a defined sidewall angle for one or more pattern elements whose sidewall angles lie outside a specified angle range. For example, a pattern element may have an edge steepness of essentially 90°, while its sidewall angle should, for example, lie within an angle range of 95° to 98°.

[0064] Changing the angle of incidence may comprise: changing the angle of incidence by > 5°, preferably by > 10°, more preferably by > 20°, and most preferably by > 40° relative to a normal incidence of the at least one massed particle beam onto a substrate of the photolithographic mask.

[0065] The acceleration voltage for examining the at least one defect may range from 100 keV to 0.01 keV, preferably from 20 keV to 0.02 keV, more preferably from 5 keV to 0.05 keV, and most preferably from 3 keV to 0.1 keV.

[0066] If electron beams are used as mass-bearing particles whose acceleration voltage is in the range of 1 keV (kiloelectronvolt), electrical voltages in the range of a few 100 V can generate electric fields that deflect the electron beams by the angles mentioned above.

[0067] The massed particle beam upon impinging on the photolithographic mask may comprise a focus diameter of 0.1 nm to 1000 nm, preferably 0.2 nm to 200 nm, more preferably 0.4 nm to 50 nm, and most preferably 0.5 nm to 20 nm.

[0068] These focus diameters of the massed particle beam are preferably used for examining a defect by illuminating it at different angles of incidence. When adjusting a sidewall angle by performing a local chemical reaction, the focus diameter is generally larger due to the accepted aberrations of the particle beam. This magnification depends on the angle of incidence of the particle beam on the respective defect location. By appropriately adjusting the particle-optical system, the aberrations and thus the magnification of the focus diameter can be minimized.

[0069] The massed particle beam may have an aperture angle of 0.1° to 60°, preferably of 0.2° to 40°, more preferably of 0.5° to 20°, and most preferably of 1° to 10°.

[0070] The larger the particle beam's aperture angle, the smaller its focus diameter. Therefore, particle beams with a large aperture angle are often used to examine a defect, whereas smaller aperture angles can also be used to adjust a sidewall angle using a local chemical reaction—depending on the required precision.

[0071] The at least one mass-carrying particle beam may comprise at least one element from the group: an electron beam, an ion beam, an atom beam and a molecular beam.

[0072] A photolithographic mask may include a transmissive photomask and a reflective photomask. A photolithographic mask may include a binary photomask or a phase-shifting photomask. Furthermore, the photolithographic mask may include a multiple exposure mask.

[0073] A photolithographic mask typically comprises a substrate with structural or pattern elements arranged thereon, or with pattern elements etched into the substrate. In this application, the surface of the photolithographic mask is understood to be an area of ​​a photomask surface that does not have any structural elements that image the incident light.

[0074] A computer program may comprise instructions that, when executed by a computer system, cause the computer system to perform the method steps according to any one of the aspects of adjusting at least one sidewall angle.

[0075] A computer program may comprise instructions that, when executed by a computer system, cause the computer system to perform the method steps according to any one of the aspects of examining the at least one defect.

[0076] In one embodiment, the device for adjusting at least one sidewall angle of at least one pattern element of a photolithographic mask comprises: (a) at least one gas supply system configured to provide at least one precursor gas; (b) at least one particle beam source configured to generate at least one mass-carrying particle beam, wherein the at least one mass-carrying particle beam is configured to excite the at least one precursor gas to a local chemical reaction; and (c) at least one adjustment unit configured to change at least one parameter of the at least one particle beam source and / or at least one process parameter during the local chemical reaction to adjust the at least one sidewall angle of the at least one pattern element;and (d) wherein the adjustment unit is further configured to change a size of a repair shape in one dimension from the beginning to the end of the local chemical reaction by at least 5% relative to a process resolution limit in one dimension.;

[0077] The setting unit may further be designed to receive at least one element from the group: - Measurement data of at least one defect recorded at different angles of incidence, - data of a three-dimensional contour of at least one defect, - parameters of a repair form of at least one defect, - Data of a defect residue of at least one defect, - a side wall angle of at least one pattern element; and - an angle of a generated sidewall.

[0078] The at least one gas supply system can be configured to supply the at least one precursor gas in a predetermined gas flow rate, at a predetermined temperature, and / or in a predetermined precursor gas composition. The gas supply system can comprise at least one element from the group: at least one reservoir configured to store the at least one precursor gas, at least one control valve configured to control a gas flow rate of the at least one precursor gas, at least one gas line system configured to conduct the at least one precursor gas from the at least one reservoir to a point of impact of the mass-bearing particle beam on the photolithographic mask, and at least one nozzle configured to concentrate the precursor gas at the point of impact of the mass-bearing particle beam on the surface of the photolithographic mask.

[0079] The at least one precursor gas may comprise at least one member from the group: at least one etching gas, at least one deposition gas and at least one additive gas.

[0080] The at least one etching gas may comprise at least one halogen-containing compound. A halogen-containing compound may comprise at least one element from the group: fluorine (F2), chlorine (Cl2), bromine (Br2), iodine (I2), xenon difluoride (XeF2), xenon tetrafluoride (XeF4), xenon hexafluoride (XeF6), xenon chloride (XeCl), hydrogen fluoride (HF), argon fluoride (ArF), krypton fluoride (KrF), sulfur difluoride (SF2), sulfur tetrafluoride (SF4), sulfur hexafluoride (SF6), phosphorus trifluoride (PF3), phosphorus pentafluoride (PF5), and nitrosyl chloride (NOCl).

[0081] The at least one deposition gas may comprise at least one element from the group: a metal alkyl, a transition element alkyl, a main group alkyl, a metal carbonyl, a transition element carbonyl, a main group carbonyl, a metal alkoxide, a transition element alkoxide, a main group alkoxide, a metal complex, a transition element complex, a main group complex, and an organic compound.

[0082] The metal alkyl, the transition element alkyl and the main group alkyl may comprise at least one element from the group: cyclopentadienyl (Cp) trimethyl platinum (CpPtMe3), methylcyclopentadienyl (MeCp) trimethyl platinum (MeCpPtMe3), tetramethyltin (SnMe4), trimethylgallium (GaMe3), ferrocene (Cp2Fe), and bis-aryl chromium (Ar2Cr).

[0083] The metal carbonyl, the transition element carbonyl and the main group carbonyl may comprise at least one element from the group: chromium hexacarbonyl (Cr(CO)6), molybdenum hexacarbonyl (Mo(CO)6), tungsten hexacarbonyl (W(CO)6), dicobalt octacarbonyl (Co2(CO)8), triruthenium docadecarbonyl (Ru3(CO) 12 ), and iron pentacarbonyl (Fe(CO)5).

[0084] The metal alkoxide, the transition element alkoxide, and the main group alkoxide may comprise at least one element from the group: tetraethylorthosilicate (TEOS, Si(OC2H5)4) and tetraisopropoxytitanium (Ti(OC3H7)4). The metal halide, the transition element halide, and the main group halide may comprise at least one element from the group: tungsten hexafluoride (WF6), tungsten hexachloride (WCl6), titanium hexachloride (TiCl6), boron trichloride (BCl3), and silicon tetrachloride (SiCl4).

[0085] The metal complex, the transition element complex and the main group complex may comprise at least one element from the group: copper bis-hexafluoroacetylacetonate (Cu(C5F6HO2)2) and dimethyl gold trifluoroacetylacetonate (Me2Au(C5F3H4O2)).

[0086] The organic compound may comprise at least one element from the group: carbon monoxide (CO), carbon dioxide (CO2), an aliphatic hydrocarbon, an aromatic hydrocarbon, a component of vacuum pump oils, and a volatile organic compound.

[0087] The at least one additive gas may comprise at least one element from the group: an oxidizing agent, a halide, and a reducing agent.

[0088] The oxidizing agent may comprise at least one element from the group: oxygen (O2), ozone (O3), water vapor (H2O), hydrogen peroxide (H2O2), nitrous oxide (N2O), nitrogen oxide (NO), nitrogen dioxide (NO2), and nitric acid (HNO3). The halide may comprise at least one element from the group: chlorine (Cl2), hydrochloric acid (HCl), xenon difluoride (XeF2), hydrogen fluoride (HF), iodine (I2), hydrogen iodide (HI), bromine (Br2), hydrogen bromide (HBr), nitrosyl chloride (NOCl), phosphorus trichloride (PCl3), phosphorus pentachloride (PCl5), and phosphorus trifluoride (PF3). The reducing agent may comprise at least one element from the group: hydrogen (H2), ammonia (NH3), and methane (CH4).

[0089] In addition, the device for adjusting a sidewall angle of at least one pattern element of a photolithographic mask can be designed to carry out the steps of the method defined above for adjusting a sidewall angle of at least one pattern element of a photolithographic mask.

[0090] In a second embodiment, the device for examining at least one defect of a photolithographic mask with at least one mass-carrying particle beam at different angles comprises: (a) at least one particle beam source configured to generate at least one mass-carrying particle beam; and (b) at least one adjustment unit configured to change an angle of incidence of the mass-carrying particle beam during the examination.

[0091] The adjustment unit may further be configured to control the change of the mean angle of incidence of the particle beam on the at least one defect of the photolithographic mask.

[0092] The adjustment unit may comprise at least one element from the group: an electrical deflection system and a magnetic deflection system.

[0093] The electrical deflection system can be part of the particle beam source, in particular, the electrical deflection system can be part of the imaging system of the particle beam source. The magnetic deflection system can be separate from the particle beam source. This means that the magnetic deflection system can be located outside the imaging system of the particle beam source.

[0094] However, it is also possible for both the electrical and magnetic deflection systems to be part of the particle beam source of the mass-carrying particle beam. For example, the electrical deflection system can be arranged in front of an electron-optical lens of the imaging system of the particle beam source, and the magnetic deflection system can be arranged behind an electron-optical lens of the imaging system of the particle beam source.

[0095] The electrical deflection system may comprise at least one pair of deflection plates. The electrical deflection system may comprise at least two pairs of deflection plates arranged parallel to each other. The electrical deflection system may be arranged in front of an electron-optical objective lens of the imaging system of the particle beam source for the massed particle beam.

[0096] The magnetic deflection system may comprise at least one pair of coils. However, the magnetic deflection system may also comprise at least one permanent magnet.

[0097] The device for examining and / or the device for adjusting a sidewall angle may further comprise: at least one sample stage configured to rotate a photolithographic mask about an axis perpendicular to the patterned surface of the photolithographic mask. The at least one sample stage may further be configured to rotate a photolithographic mask by an angle perpendicular to the patterned sample normal. The adjustment unit may further be configured to control or regulate the rotation of the sample stage.

[0098] Viewed in spherical coordinates and assuming that the optical axis of the photolithographic mask is parallel to the z-axis of a spherical coordinate system, the at least one sample stage is configured to change a polar angle between the particle beam and the optical axis. Because the at least one sample stage allows not only a change in the polar angle but also a change in the azimuth angle, improved processing of the photolithographic mask can be performed by means of a local chemical reaction at any location or side of a pattern element of the photomask.

[0099] The imaging system of the particle beam source can be configured to be rotatable about an axis perpendicular to the normal of the patterned surface of a photolithographic mask. The adjustment unit can further be configured to control or regulate the rotation of the imaging system. Furthermore, the particle beam source can be configured to be rotatable about an axis perpendicular to the normal of the patterned surface of a photolithographic mask. Furthermore, the adjustment unit can be configured to control or regulate the rotation of the particle beam source. Furthermore, the adjustment unit can be configured to control or regulate both the sample stage and the imaging system or the particle beam source to change an angle of incidence.

[0100] The at least one sample stage can be rotatable about a third axis, wherein the third axis of rotation of the sample stage is substantially perpendicular to the normal of the patterned surface of the photolithographic mask. It is advantageous if the third axis of rotation is also perpendicular to the second axis of rotation of the sample stage, so that the three axes of rotation of the sample stage form a rectangular coordinate system.

[0101] A combination of changing the mean angle of incidence of the massed particle beam on the surface of the photolithographic mask, which reduces the mean angle of incidence in one direction, and a sample stage rotatable around the optical axis of the photolithographic mask allows the mean angle of incidence of the massed particle beam to be adjusted in two spatial directions. This enables access to any processing location on the photolithographic mask. This allows the adjustment of any sidewall angle of a pattern element of a photolithographic mask.

[0102] Furthermore, the adjustment unit can be configured to deflect the mass-bearing particle beam in two directions. The two deflection directions of the adjustment unit can be substantially at an angle of 90° to each other.

[0103] The device for examining and / or the device for adjusting a sidewall angle of at least one pattern element of a photolithographic mask can further comprise at least one detector configured to detect the particles originating from the photolithographic mask and caused by the massed particle beam. The particles originating from the photolithographic mask can comprise the particle type of the massed particle beam. The particles originating from the photolithographic mask can be different from the particle type of the massed particle beam.

[0104] The device for examining and / or the device for adjusting a sidewall angle may further comprise: an evaluation unit which is designed to analyze the data of the at least one defect recorded at different angles of incidence.

[0105] The evaluation unit can further be configured to generate a three-dimensional contour of the at least one defect from the data recorded at different angles of incidence. In particular, the evaluation unit can generate image data from the scan data of the mass-carrying particle beam. The image data can be stored and / or displayed on a screen of the device for examining at least one defect and / or the device for adjusting a sidewall angle.

[0106] The evaluation unit can further be designed to determine at least one change in the mean angle of incidence of the mass-bearing particle beam on the surface of the photolithographic mask from the analyzed scan data.

[0107] The evaluation unit can also be configured to determine a change to be set in the mean angle of incidence of the mass-bearing particle beam from the kinetic energy of the particle beam for executing the local chemical reaction. Furthermore, the evaluation unit can be configured to determine the change to be set in the mean angle of incidence of the mass-bearing particle beam from a material composition of the local chemical reaction.

[0108] The kinetic energy of the particles of the massed particle beam and the material composition encountered by the particles of the particle beam influence the size of the interaction area of ​​the particle beam with the photolithographic mask and thus the area of ​​the mask that can be affected by the execution of a local chemical reaction.

[0109] The evaluation unit can further be designed to determine an area and a material composition for a locally limited protective layer around a processing location of a defect or a processing location for setting an edge steepness.

[0110] A localized protective layer can be deposited around a defect on the photomask substrate prior to performing a local chemical reaction to protect the mask substrate from damage during the local chemical reaction. A localized protective layer can be removed from the mask substrate after the completion of the local chemical reaction using an EBIE process. Alternatively, a protective layer can be removed from the mask using a mask cleaning step.

[0111] The evaluation unit can further be designed to determine from the analyzed data at least one change to be set in the angle of incidence of the mass-bearing particle beam on the photolithographic mask.

[0112] In addition, the evaluation unit can be designed to determine the parameters of a repair form from the analyzed data.

[0113] The inspection device can transmit the measurement data to the sidewall angle adjustment device, and the sidewall angle adjustment device or its evaluation unit can determine the parameters of a repair shape for eliminating the defect and / or for adjusting the required edge steepness of one or more pattern elements of the mask under inspection. However, it is also possible for the inspection device or its evaluation unit to calculate a parameterized repair shape for repairing the defect and / or for adjusting the edge steepness of one or more sidewalls of one or more pattern elements from the measurement data recorded at different angles and to transmit the parameterized repair shape to the sidewall angle adjustment device.

[0114] Furthermore, both the device for testing and the device for adjusting a sidewall angle can include an evaluation unit. Alternatively, it is also possible for an evaluation unit to be divided between a device for testing and a device for adjusting a sidewall angle. The device for testing and the device for adjusting a sidewall angle can communicate via a wireless or wired interface.

[0115] In addition, it is possible for the device for examining and the device for adjusting a side wall angle to be integrated into a single device.

[0116] The adjustment unit may further be configured to control the change in the angle of incidence of the massed particle beam onto the at least one pattern element of the photolithographic mask based on a parameterized repair shape.

[0117] Furthermore, the adjustment unit can be designed to carry out a change of at least one parameter of the at least one mass-bearing particle beam, a process parameter, and / or the change of the angle of incidence of the mass-bearing particle beam in an automated manner.

[0118] Finally, the device for examining at least one defect of a photolithographic mask can be designed to carry out the steps of the method defined above for examining at least one defect of a photolithographic mask. 4. Description of the drawings

[0119] In the following detailed description, currently preferred embodiments of the invention are described with reference to the drawings, wherein Fig. 1 shows in the upper part a schematic section of an edge of a pattern element of a photolithographic mask, as specified by the design, and in the lower part a defect-free edge of the pattern element of the upper part; Fig. Figure 2a shows a schematic section through a mask for the extreme ultraviolet (EUV) wavelength range, the pattern elements of which have edge steepnesses of α = 90°; Fig. 2b shows the section of the EUV mask of the Fig. 2a, where the sidewall angles (SWA) of the pattern elements open upwards, ie α < 90°; Fig. 2c shows the section of the EUV mask of the Fig. 2a, where the pattern elements have an undercut, ie α > 90°; Fig. 3 schematically shows the impact of EUV radiation on the EUV mask of the partial image of the Fig. 2a and its reflection is illustrated; Fig. 4 schematically shows the incidence of EUV radiation on the EUV mask of the partial image of the Fig. 2b and their reflection by the multilayer structure of the EUV mask; Fig. 5 schematically shows the incidence of EUV radiation on an EUV mask with an open pattern element (α < 90°) and a pattern element with an edge steepness of α = 90°; Fig. 6 A: presents a schematic section through an ideal depression of a photomask, B: shows an ideal edge of a photomask, C: schematically illustrates an Electron Beam Induced Etching (EBIE) process, D: represents a real depression generated by an EBIE process, and E: represents a real edge generated by an EBIE process; Fig. Figure 7 shows a schematic section of an edge of a pattern element of a photolithographic mask having a defect in the form of excess material; Fig. 8 a schematic section of the edge of the pattern element of the Fig. 7 after performing a local chemical reaction or a local repair process to remove the defect according to the prior art; Fig. 9 in the upper part of the picture the lower part of the Fig. 1, where a particle beam with an aperture angle β impinges on the photolithographic mask, and in the lower part of the image the intensity distribution in the focus of the particle beam of the upper part of the image of Fig. 9 illustrated; Fig. 10 an interaction region (“scatter bulb”) of the particle beam of the Fig. 9 when processing an edge or a side wall of the pattern element of the photolithographic mask of the lower part of the Fig. 1 according to the state of the art; Fig. 11 schematically illustrates the execution of a particle beam-induced deposition process according to the prior art; Fig. 12 shows a schematic section through some components of an apparatus for inspecting a photolithographic mask; Fig. 13 an enlarged section of the device of the Fig. 12 with a deflection system in the form of a magnetic deflection system at the output of a column of a scanning electron microscope; Fig. 14 an enlarged section of the device of the Fig. 12 with a deflection system in the form of an electrical deflection system at the sample-side end of the column of the scanning particle microscope; Fig. 15 shows a schematic section through some components of an apparatus for adjusting a sidewall angle of a pattern element of a photolithographic mask; Fig. 16 a schematic section of a combination of the devices of the Fig. 12 and Fig. 15; Fig. 17 shows the examination of an edge of a multilayer structure of an EUV mask with a mass-carrying particle beam deflected from the optical axis; Fig. 18 presents a flowchart of a method for inspecting a defect of a photolithographic mask; Fig. 19 schematically illustrates the etching of a recess and an edge into a sample with a deflected massed particle beam using an EBIE process; Fig. 20 schematically illustrates the execution of an ion beam induced etching process according to the prior art; Fig. 21 schematically illustrates the execution of an ion beam-induced etching process, wherein the ion beam impinges on the sample at an angle of less than 90°; Fig. 22 schematically illustrates the impact of an electron beam deflected from the optical axis with a large aperture angle onto a side wall of a pattern element; Fig. 23 schematically shows the execution of an inspection process or an etching process of the side wall of a pattern element with the electron beam of the Fig. 22; Fig. 24 schematically illustrates the deposition of material onto a pattern element using a deflected electron beam; Fig. 25 schematically presents the etching of a defect using a repair mold according to the prior art; Fig. 26 schematically shows the etching of the defect of the Fig. 25 shows a repair shape changing during the etching process; Fig. 27 shows the generation of different sidewall angles when etching a recess into the substrate of a photomask with a massed particle beam with an asymmetric beam profile; and Fig. 28 shows a flowchart of the method for adjusting a sidewall angle of a pattern element of a photolithographic mask. 5. Detailed description of preferred embodiments

[0120] In the following, currently preferred embodiments of a method according to the invention and of an apparatus according to the invention for adjusting a sidewall angle of a pattern element of a photolithographic mask are explained in more detail. Furthermore, exemplary embodiments of a method according to the invention and of an apparatus according to the invention for examining a defect in a photomask are explained in detail. The methods according to the invention are described using the example of a photomask for the extreme ultraviolet (EUV) wavelength range. However, these are not limited to improving the imaging behavior of EUV masks. Rather, they can be used to correct defects of any type of photomask and to adjust the sidewall angles or edge steepness of pattern elements of any type of photomask. In the following, the term mask or photomask is also intended to include a template for nanoimprint lithography (NIL).

[0121] The devices according to the invention for adjusting a sidewall angle of a pattern element and / or for examining a defect in a photolithographic mask are explained using the example of a modified scanning electron microscope. However, the devices according to the invention can be implemented not only on the basis of a scanning electron microscope. Rather, devices according to the invention can be based on any scanning particle microscope, i.e., a device defined in this application can use any mass-bearing particle type for examining and / or processing a photomask. Furthermore, devices according to the invention and methods according to the invention can be used not only to process photolithographic masks. Rather, the devices and methods explained can be used to analyze and / or process various microstructured components.Examples include wafers, ICs (integrated circuits), MEMSs (micro-electromechanical systems) and PICs (photonic integrated circuits).

[0122] The upper part of image 105 of the Fig. 1 schematically shows a section of a portion of a photolithographic mask 100. The mask 100 can be a transmitting or a reflecting mask 100. In the example of Fig. 1, the photomask 100 comprises a substrate 110 and a pattern element 120 or a structural element 120. The substrate 110 can comprise a quartz substrate and / or a material with a low thermal expansion coefficient (LTE (low thermal expansion) substrate). The pattern element 120 can be a structural element 120 of a binary photomask 100. In this case, the pattern element 120 can comprise an element of an absorber structure 120 and, for example, comprise chromium. However, the pattern element 120 can also comprise a structural element 120 of a phase-shifting photomask 100. A phase-shifting mask 100 can be produced, for example, by etching a corresponding pattern into the substrate 110 of the mask 100.Furthermore, it is possible for the pattern element 120 to comprise a structural element 120 that both shifts the phase of the actinic radiation relative to the radiation incident on the substrate 110 and absorbs a portion of the light of the actinic wavelength incident on the pattern element 120. Examples of this are OMOG (opaque MoSi (molybdenum silicide) on glass) masks.

[0123] The upper part of image 105 of the Fig. 1 shows an ideal edge 130 specified by the design or a section through a sidewall 130. The edge 130 of the pattern element 120 is determined by the edge steepness 140 or the sidewall angle 140. Furthermore, the edge 130 or the sidewall 130 is characterized by the radii 135 and 145 or the radii of curvature 135 and 145, with which the sidewall 130 transitions, on the one hand, into the surface 115 of the substrate 110 of the mask 100 and, on the other hand, into the flat surface 125 of the pattern element 120. Typically, the design specifies an edge steepness 140 or a sidewall angle 140 of substantially α = 90°. The radii of curvature 135 and 145 of the edges 130 or the side walls 130 of the pattern elements 120 should be as small as possible, ie as close to zero as possible.

[0124] The lower part of the image 155 of the Fig. 1 presents a section through a pattern element 120 produced on the substrate 110 of the photomask 150, which was manufactured according to the design specifications discussed above. The edge steepness 170 or the sidewall angle 170 of the sidewall 160 or the edge 160 essentially has an angle of α = 90° and thus agrees well with the design specification. The radii of curvature 165 and 175 of the sidewall 160 are not zero but are sufficiently small for the pattern element 120 to fulfill its function. This means that a photolithographic mask 100, whose structural elements 120 have sidewalls 160 or edges 160 with the sidewall angle 170, as shown in the lower partial image 155 of the Fig. 1, meets the specification.

[0125] The Fig. Figure 2a shows a schematic section through a portion of a photolithographic mask 200 for the EUV wavelength range. A multilayer structure 210 is applied to its substrate 110. The multilayer structure may, for example, comprise 20 to 60 alternating layers of molybdenum (Mo) and silicon (Si). Two structural or pattern elements 220 and 230 are deposited on the multilayer structure 210. The pattern elements 220, 230 of the EUV mask 200 may, for example, comprise tantalum nitride (TaN). A coordinate system 235 is drawn in the right-hand pattern element 220, which is used to define an edge steepness 170 or a sidewall angle 170. In the Fig. 2a, the side wall angle 170 of the two pattern elements 220, 230 essentially has a value of α = 90°.

[0126] The Fig. Figure 2b illustrates a section of an EUV mask 240, which is constructed similarly to the EUV mask 200 of the Fig. 2a. In contrast to the EUV mask 200 of the Fig. 2a, the pattern elements 250 and 260 have edge steepnesses 170 that deviate from 90°. The pattern elements 250 and 260 open upwards and, as illustrated by the coordinate system 235, have a sidewall angle 170 that is less than 90°. The opening 245 formed by the pattern elements 250 and 260 becomes larger toward the top.

[0127] The Fig. Figure 2c shows a section of an EUV mask 270 whose pattern elements 280 and 290 have an undercut, i.e., the opening 275 tapers upwards. This configuration is characterized by a sidewall angle α > 90°.

[0128] The Fig. 3 schematically illustrates the exposure of the EUV mask section 200 of the Fig. 2a with light at the actinic wavelength. Since the EUV mask 200 is designed as a reflective mask 200, its illumination occurs at an angle of ≠ 0°. Currently, the angle of the chief ray 310 (CRA or Chief Ray Angle) has a deviation from the normal of the EUV mask 200 in the range of 5° to 6°. In the Fig. 3 - as in the following Fig. 4 and Fig. 5 - the EUV masks are exposed to dipole radiation. This is symbolized by the two beams 320 and 330 incident on the mask 200. The beam 320 is partially shaded or absorbed by the pattern element 230 and strikes the multilayer structure 220 of the EUV mask 200 as a beam of reduced intensity 325. The beam 325 is reflected by the multilayer structure 220 as EUV light beam 360, whereas the light beam 330 is reflected as beam 350. The reference numeral 340 in the Fig. 3 shows the reflected CRA 310. The partial shadowing of the light beam 320 by the pattern element 230 results in a loss of contrast during lithographic imaging through the EUV mask 200. To minimize this problem, the thickness of the absorbing pattern elements 220, 230 of the EUV masks 200 is chosen to be as small as possible. Typical thicknesses of the pattern elements 220, 230 are less than 50 nm.

[0129] The Fig. 4 schematically shows the exposure of the EUV mask section 240 of the Fig. 2b also with light of the actinic wavelength. As in the context of the Fig. 3, the illumination is carried out at an angle of 5° on the CRA 410. Unlike in the Fig. 3, due to the sidewall angle 170 α < 90° of the pattern elements 250 and 260, the beam 420 can impinge unhindered on the multilayer structure 210. As a result, the two incident light beams 420 and 430 are reflected with the same intensity as EUV beams 450 and 460, thus avoiding a loss of contrast when imaging the EUV mask 240.

[0130] The Fig. Figure 5 shows a section of an EUV mask 500, in which the left pattern element 220 has an edge steepness 170 of α = 90°. In contrast, the right pattern element 260 has a sidewall angle 170 α < 90°. An advantage of this edge steepness 170 in the case of a non-perpendicular incidence is in the context of Fig. 4. The light beams 520 and 530 of a dipole radiation source are incident on the multilayer structure 210 of the EUV mask 500. As indicated by the arrow 560 in the Fig. 5, a portion of the EUV radiation reflected by the multilayer structure 210 is absorbed by the pattern element 220. Another portion is reflected by the side wall 570 of the pattern element 220 and forms an interference pattern (in the Fig. 5 not shown) near the side wall 570 of the pattern element 220.

[0131] Due to the reflection at the sidewall 570, which has a sidewall angle α = 90°, a portion of the EUV radiation reflected by the multilayer structure 210 is redistributed. This redistribution can be advantageous depending on the respective application and can positively influence the imaging behavior of the EUV mask 500. This means that an EUV mask 500 whose pattern elements 220, 260 have asymmetric sidewall angles 170 can, in principle, lead to a distribution of the radiation 540, 565 reflected by the EUV mask 500 that can be adjusted by the edge steepness 170, thereby achieving a desired effect.

[0132] The Fig. 6 illustrates in partial image A the generation of a rectangular profile 610 in a photolithographic mask 600, as specified by the design of the mask 600, using an exemplary EBIE (Electron Beam Induced Etching) process. The generation of the rectangular profile 610 can, for example, be carried out in a substrate 110, in a multilayer structure 210, or in a pattern element 220, 230, 250, 260, 280, 290. The radii of curvature 605 and 615 of the rectangular profile 600 have a very small numerical value. Partial image B of the Fig. Figure 6 shows an ideal edge 620 etched into the photomask 600. The radii of curvature 625 and 635 of the ideal edge 620 also have very small values ​​and are very close to an ideal curvature radius of zero.

[0133] Part C of the Fig. Figure 6 schematically illustrates the execution of an EBIE process to generate the rectangular profile 610 of the partial image A of the Fig. 6. A precursor gas in the form of an etching gas 640 is provided in the area of ​​the profile 610 to be created. A focused electron beam 630 or secondary electrons 650 released by the focused electron beam 630 from the material of the photomask 600 induce the EBIE process by breaking down the molecules of the etching gas and thus producing at least one reactive type of particle. These reactive particles react with the material of the photomask 600.

[0134] Although the electron beam 630 is periodically scanned over the base area of ​​the profile, the beam shown in the partial image D of the Fig. The actual EBIE process shown in Figure 6 does not produce the rectangular profile 610 specified by the design, but rather a profile 660 that is more like a trough. The edge steepness 670, or the sidewall angle 670, deviates significantly from the sidewall angle α = 90° required by the design. Furthermore, the radii of curvature 665 and 675 of the produced trough have significantly larger numerical values ​​than the radii of curvature 605 and 615 of the rectangular profile 610.

[0135] Partial image E presents a real edge 680 created using an EBIE process. The edge steepness 670 of the etched edge 680 is significantly smaller than the sidewall angle of α = 90° specified by the design. Furthermore, the actually generated curvature radii 685 and 695 have significantly larger numerical values ​​than the curvature radii 625 and 635 of the ideal edge 620 specified in partial image B.

[0136] As shown in part C of the Fig. 6, the electron beam 630 strikes the photolithographic mask 600 perpendicularly. At least part of the deficiencies illustrated in panels D and E when performing an EBIE process is due to the perpendicular incidence of the electron beam 640 on the photomask 600.

[0137] The Fig. 7 shows a schematic section through a photolithographic mask 700 with a substrate 110 and a pattern element 120 having excess material 750 at the edge 160 or the sidewall 160. The excess material 750 may comprise material of an absorbing or phase-shifting pattern element 120 or material of the substrate 110. However, the defect of excess material 750 may also be a particle that has settled at the edge 160 of the pattern element 120. Excess material 750 in the form of a particle typically has a material composition that differs from that of the photomask 700.

[0138] In the Fig. In the example shown in Figure 7, the excess material defect 750 has the same height as the pattern element 120. However, this is not a prerequisite for applying a method or device described in this application for examining the defect 750 and / or for processing the excess material defect 750 or for adjusting a sidewall angle 170, 670. Rather, the devices explained below can examine and / or process defects of missing and / or excess material 750 that have virtually any shape.

[0139] The Fig. 8 presents the cut of the section of the mask 700 of the Fig. 7 after removing the excess material 750 or the defect of excess material 750 by means of a local particle beam-induced etching process, such as an EBIE process according to the prior art. Fig. 8, it can be seen that the sidewall angle α' of the sidewall 860 created by the local etching process deviates significantly from the angle of α = 90° required by the design. Furthermore, the radii of curvature 880, 885 of the sidewall 860 of the generated pattern element 820 are different from the angle shown in the lower part of the image 155 of the Fig. 1. Furthermore, the local etching process has removed a portion 850 of the substrate 110 of the mask 700 in and around the area previously covered by the excess material 750. As a result of the explained adverse effects of the local etching process, the repaired mask 800 still does not meet the imaging specification specified for the photomask.

[0140] Based on the Fig. 8, the difficulties in processing a defect of excess material 750 by performing a particle beam-induced local etching process were explained above. A second class of frequently occurring defects in photolithographic masks are defects of missing material, such as missing absorber material in binary masks (in the Fig. 8 not shown). Similar to local etching, the local deposition of missing material, such as missing absorber material, using a particle beam-induced deposition process, such as an EBID (Electron Beam Induced Deposition) process, produces edge steepnesses of the sidewalls of the deposited pattern elements that deviate significantly from 90°. Furthermore, the sidewalls formed during the repair cannot be influenced, or can only be influenced to a very limited extent. In addition, the radii of curvature of the deposited pattern elements are often significantly larger than the radii of curvature 165, 175 of pattern elements 120 produced in the original manufacturing process of the defect-free mask 150. Moreover, as a result of the local deposition process, material is deposited in an undesirable manner on parts of the surface 115 of the substrate 110 that should be free of deposited material, or parts of the substrate 110 are etched in an undesirable manner.

[0141] This means that the local deposition process creates a kind of halo around the local processing location. Typically, the additional material deposited on portions of the surface 115 of the substrate 110 and the deficiencies of a local EBID process described above locally impair the functionality of a repaired photolithographic mask.

[0142] Based on the Fig. 9 and Fig. 10, at least some of the reasons for the above-mentioned in the context of Fig. 8 discussed problems.

[0143] The upper part of image 905 of the Fig. 9 reproduces the section of the lower part of the photolithographic mask 150 of the Fig. 1. A particle beam 910 having an aperture angle β strikes the substrate 110 of the mask 150. The aperture angle β can range from fractions of a degree to several degrees. The particle beam 910 strikes the surface 115 of the substrate 110 of the mask 150 essentially perpendicularly.

[0144] The lower part of image 955 of the Fig. 9 shows the intensity distribution of the particle beam 910 in its tip 920 or its focus 920 or at the point of impact of the particle beam 910 on the surface 115 of the substrate 110 of the mask 150 of the Fig. 1. Typically, the particle beam 910 exhibits a Gaussian or Gaussian-like intensity profile at its focus 920. The minimum achievable full width half maximum (FWHM) 950 depends on the particle type of the particle beam 910. Currently, electron beams can be focused at the focus to a spot diameter ranging from the nanometer range to the subnanometer range.

[0145] In order to achieve the highest possible spatial resolution for examining a sample, such as a defect 750, it is necessary to focus the particle beam 910 onto a small spot 950 at the examination location. This often also applies to processing a sample, for example, repairing a defect 750 and / or adjusting a sidewall angle 170, 670 of a pattern element 120 of a photomask 700. Similar to the optical area, the requirement for a small spot diameter in the focus requires a large aperture angle β for the particle beam 910. As shown in the upper part of the image 905 of the Fig. 9, however, a large aperture angle β of the particle beam 910 hinders the accessibility of the particle beam 910 to examination, processing and / or repair locations located near edges 160 or steep side walls 160 of pattern elements 120.

[0146] The Fig. 10 reproduces again the mask section 150 of the Fig. 1, wherein in addition the particle beam 910 of the Fig. 9 impinges on the material of the photolithographic mask 150. The reference numeral 1010 in the Fig. 10 denotes the interaction region that the particle beam 910 creates upon impinging on the substrate 110 of the photolithographic mask 150. When the particle beam 910 impacts the substrate 110, its particles, for example electrons, are scattered in the electrostatic field of the atomic nuclei of the substrate material 110. The energy of the impinging particles of the particle beam 910 creates secondary products in the interaction volume 1010 or the scattering bulb 1010. For example, the scattering processes of the impinging particles with the atomic nuclei transfer energy to the lattice of the substrate material 110 of the mask 150, whereby the substrate material 110 is locally heated. The electrons of the substrate material 110 can also absorb energy from the primary particles of the particle beam 910 impinging on the substrate 110 at point 1020 through scattering processes and be released as secondary electrons and / or as backscattered electrons.The size and shape of the interaction region 1010 depend on the particle type of the particle beam 910 and the kinetic energy of the particles of the particle beam 910 impinging on the substrate 110. Furthermore, the material or material composition of the substrate 110 influences the size and shape of the scattering bulb 1010.

[0147] During a machining process, such as the repair of a defect 750 and / or the adjustment of a sidewall angle 670, molecules of a precursor gas are adsorbed on the surface 115 of the substrate 110 near a location to be machined. Molecules of a precursor gas present in the region of the impact point 1020 of the particle beam 910 on the surface 115 of the substrate 110 of the mask 150, 200 are broken down into their components by the processes occurring in the interaction region 1010—for example, by the absorption of secondary electrons and / or backscattered electrons.

[0148] When the particle beam 910 strikes the substrate 110, the interaction region 1010 or the scattering bulb 1010 lies essentially within the substrate 110 of the mask 150. If the particle beam 910 strikes the edge 160 or the side wall 160 of the pattern element 120 of the mask 150, only a part of the processes taking place in the interaction region 1010 take place in the material of the pattern element 120 of the mask 150. This is shown in the Fig. 10 by the deformed or substantially halved interaction region 1050. A portion of the secondary or backscattered particles 560 generated in the deformed interaction region 1050 can leave the interaction region 1050 and reach the surface 115 of the substrate 110 of the mask 100. This is shown in the Fig. 10 by the arrows 1060. Unlike in the material of the pattern element 120, hardly any interaction processes take place in the vacuum environment in which the mask 150, 200 is typically located during an inspection and / or processing process.

[0149] As already explained above, during a processing process of the photolithographic mask 150, the surface 115 of the substrate 110 of the mask 150 in the region of the edge 160 or the side wall 160 of the pattern element 120 is covered with molecules of the precursor gas 640. The secondary particles 1060 impinging on the surface 115 of the substrate 110, which are released by the particle beam 910 in the deformed interaction region 1050, initiate undesired local processing processes on the substrate 110. If the precursor gas 640 is present in the form of an etching gas 640, this is an etching process of the substrate 110, which, as in the Fig. 8, leads to a local depression 850 of the substrate 110. Precursor gases, which are present in the form of deposition gases, on the other hand, often lead to local undesired deposition processes in the form of a halo, for example, on the substrate 110 of the photolithographic mask 150, 700.

[0150] The diagram 1100 of the Fig. Figure 11 illustrates the correction of a defect of missing material by depositing material 1150 along the sidewall 170 of the pattern element 120 onto the substrate 110 of the photolithographic mask 150. The Fig. Figure 11 illustrates the execution of an EBID process according to the prior art. In the context of Fig. 10, it was explained that the electron beam 910, upon impinging on the surface 115 of the substrate 110 of the mask 150, creates an interaction region 1010 in the substrate. The processes occurring in the interaction region 1010 enable the splitting of the molecules of a precursor gas 640 adsorbed on the surface 115 of the substrate 110. If the molecules of the precursor gas adsorbed on the surface 115 of the substrate 110 are a deposition gas, a constituent or component of the molecules of the deposition gas split by the action of the electron beam 910 can be deposited or deposited on the surface 115 of the substrate 110. For example, a metal carbonyl is split into a metal atom or metal ion and carbon monoxide by the direct action of the electron beam 910.The metal atom can settle on the surface 115 of the substrate 110, while the volatile carbon monoxide molecules can largely leave the processing site.

[0151] By sequentially scanning the focused electron beam 910 over the region of missing material 1150, the missing material is deposited layer by layer on the substrate 110 in the presence of the deposition gas. However, the size of the interaction region 1110 generated by the electron beam 910 in the substrate 110 or in the deposit 1150 or deposited material 1150 prevents the deposition of sidewalls 170 or edges with a sidewall angle 670 of substantially α = 90°. Rather, the size of the interaction region 1110 at least partially determines the size of the edge steepness 1170 α'' of the sidewall 1160 or the edge 1160 of the deposit 1150. Similar to performing a local etching process, the size and shape of the interaction region 1110 depends on the kinetic energy of the electrons of the electron beam 910 and the material composition of the deposit 1150.However, neither performing a local particle beam-induced etching process nor performing a local particle beam-induced deposition process allows setting a sidewall angle of 170, 670, 1170.

[0152] The Fig. 12 shows a schematic section through some important components of a device 1200 that can be used to examine one or more defects 750 of a photolithographic mask 700. The exemplary device 1200 of Fig. 12 comprises a modified scanning particle microscope 1210 in the form of a scanning electron microscope (SEM) 1210.

[0153] The device 1200 has a particle beam source 1205 in the form of an electron beam source 1205, which generates an electron beam 1215 as a mass-carrying particle beam 1215. An electron beam 1215 has the advantage, compared to an ion beam, that the electrons impinging on the sample 1225 or the photolithographic mask 700 can essentially not damage the sample 1225 or the photomask 700. However, it is also possible to use an ion beam, an atom beam, or a molecular beam in the device 1200 to process the sample 1225 (in the Fig. 12 not shown).

[0154] The scanning particle microscope 1210 consists of an electron beam source 1205 and a column 1220 in which the beam optics 1213 is arranged, approximately in the form of an electron optics of the SEM 1210. In the SEM 1210 of the Fig. 12, the electron beam source 1205 generates an electron beam 1215 which is reflected by the imaging elements arranged in the column 1220, which are arranged in the Fig. 12, is directed as a focused electron beam 1215 at location 1222 onto the sample 1225, which may include the photolithographic mask 700. Thus, the beam optics 1213 forms the imaging system 1213 of the electron beam source 1205 of the SEM 1200.

[0155] The imaging elements of the column 1220 of the SEM 1210 can also rasterize or scan the electron beam 1215 across the sample 1225. The sample 1225 can be examined using the electron beam 1215 of the SEM 1210. Typically, the electron beam 1215 impinges perpendicularly on the sample 1225 (in the Fig. 12 (not shown). Rather, the SEM 1210 of the device 1200 has a deflection system 1203. This can deflect the electron beam 1215 from the vertical so that the electron beam 1215 impinges on the sample 1225 at an angle of less than 90°. This allows the sample 1225 to be analyzed in greater detail. The limited spatial resolution of a massive particle beam 1215 in the beam direction can thus be at least partially overcome.

[0156] The backscattered electrons and secondary electrons generated by the electron beam 1215 in the interaction region 1010, 1050, 1110 of the sample 1225 are registered by the detector 1217. The detector 1217, which is arranged in the electron column 1220, is referred to as an "in-lens detector." In various embodiments, the detector 1217 can be installed in the column 1220. The detector 1217 converts the secondary electrons generated by the electron beam 1215 at the measuring point 1222 and / or the electrons backscattered by the sample 1225 into an electrical measurement signal and forwards this to an evaluation unit 1285 of a computer system 1280 of the device 1200. The detector 1217 can contain a filter or a filter system to discriminate the electrons in energy and / or solid angle (in the Fig. 12 is not shown). The detector 1217 is controlled by a setting unit 1290 of the device 1200.

[0157] The exemplary device 1200 may include a second detector 1219. The second detector 1219 may be configured to detect electromagnetic radiation, particularly in the X-ray range. Thus, the detector 1219 enables the analysis of a material composition of the radiation generated by the sample 1225 during its examination. The detector 1219 is also controlled by the adjustment unit 1290.

[0158] Furthermore, the device 1200 may comprise a third detector (in the Fig. 12 not shown). The third detector is often an Everhart-Thornley detector and is typically located outside column 1220. It is generally used to detect secondary electrons.

[0159] The device 1200 may include an ion source that provides ions with low kinetic energy in the region of the sample 1225 (in the Fig. 12 not shown). The ions with low kinetic energy can compensate for charging of the sample 1225. Furthermore, the device 1200 can have a grid at the exit of the column 1220 of the modified SEM 1210 (in the Fig. 12 (also not shown). By applying an electrical voltage to the grid, an electrostatic charge on a sample 1225 can also be compensated. Furthermore, it is possible to ground the grid.

[0160] The sample 1225 is placed on a sample stage 1230 or a sample holder 1230 for examination. A sample stage 1230 is also known in the art as a “stage.” As shown in the Fig. 12 symbolized by the arrows, the sample table 1230 can be moved, for example, by micromanipulators, which are located in the Fig. 12 are not shown, are moved in three spatial directions relative to the column 1220 of the SEM 1210.

[0161] In addition to the translational movement, the sample table 1230 can be rotated at least about one axis that is oriented parallel to the beam direction of the particle beam source 1205. It is also possible for the sample table 1230 to be designed to be rotatable about one or two further axes, wherein these axes are arranged in the plane of the sample table 1230. Preferably, the two or three axes of rotation form a rectangular coordinate system. Fig. 12, the rotation of the sample table 1230 about a rotation axis arranged in the plane of the sample table 1230 is often only possible to a limited extent due to the small distance between the column end and the sample 1225.

[0162] The sample 1225 to be examined can be any microstructured component or part that requires analysis and possibly subsequent processing, for example, the repair of a local defect 750 and / or the adjustment of a sidewall angle 670 of a pattern element 120 of a photolithographic mask 700. For example, the sample 1225 can comprise a transmissive or reflective photomask 700 and / or a template for the nanoimprint technique. The transmissive and reflective photomasks 150, 700 can comprise all types of photomasks, such as binary masks, phase-shifting masks, OMOG masks, or masks for double or multiple exposure.

[0163] The device 1200 of the Fig. 12 may further comprise one or more scanning probe microscopes, for example in the form of an atomic force microscope (AFM) (in the Fig. 12 not shown) that can be used to analyze and / or process the sample 1225.

[0164] The Fig. 12 is operated in a vacuum chamber 1270. To generate and maintain a vacuum required in the vacuum chamber 1270, the SEM 1210 of the Fig. 12 a pump system 1272.

[0165] The device 1200 includes a computer system 1280. The computer system 1280 includes a scanning unit 1282 that scans the electron beam 1215 across the sample 1225. Furthermore, the computer system 1280 includes an adjustment unit 1290 for adjusting the various parameters of the modified scanning particle microscope 1210 of the device 1200 and for changing one or more of these parameters while examining the sample 1225 with the electron beam 1215. Furthermore, the adjustment unit 1290 can control the deflection system 1203 and a rotation of the sample stage 1230.

[0166] Furthermore, the computer system 1280 has an evaluation unit 1285, which analyzes the measurement signals from the detectors 1217 and 1219 and generates an image of the sample 1225 therefrom, which is displayed on the display 1295 of the computer system 1280. In particular, the evaluation unit 1285 is designed to determine the position and contour of a defect of missing material and / or a defect of excess material 750 of a sample 1225, such as the photolithographic mask 700, from the measurement data of the detector 1217. The evaluation unit 1285 can also contain one or more algorithms that make it possible to determine a repair shape corresponding to the analyzed defect 750 of the mask 700. In addition, the evaluation unit 1285 of the computer system 1280 can contain one or more algorithms that can determine the parameters of the deflection system 1203. Examples of deflection systems 1203 for the electron beam 1215 are described below using the Fig. 13 and Fig. 14. The algorithms of the evaluation unit 1285 can be implemented in hardware, software, or a combination thereof. In particular, the algorithm(s) can be implemented in the form of an ASIC (Application Specific Integrated Circuit) and / or an FPGA (Field Programmable Gate Array).

[0167] The computer system 1280 and / or the evaluation unit 1285 may include a memory, preferably a non-volatile memory (in the Fig. 12 not shown), which stores one or more models of repair shapes for different mask types. The evaluation unit 1285 can be configured to calculate a repair shape for the defect(s) 750 of the photolithographic mask 700 from the measurement data of the detector 1217 based on a repair model. Furthermore, the computer system 1280 can have an interface 1287 for exchanging data with the Internet, an intranet, and / or another device, for example, a device for adjusting a sidewall angle. The interface 1287 can comprise a wireless or a wired interface.

[0168] The evaluation unit 1285 and / or the setting unit 1290 can, as in the Fig. 12, be integrated into the computer system 1280. However, it is also possible to implement the evaluation unit 1285 and / or the setting unit 1290 as independent units within or outside the device 1200. In particular, the evaluation unit 1285 and / or the setting unit 1290 can be designed to perform part of their tasks using a dedicated hardware implementation.

[0169] The computer system 1280 may be integrated into the device 1200 or may be configured as a standalone device (in the Fig. 12 not shown). Computer system 1280 may be implemented in hardware, software, firmware, or a combination.

[0170] The diagram 1300 of the Fig. 13 shows an enlarged section of the device 1200 in the region of the point of impact 1322 of the electron beam 1215 on the photolithographic mask 700 of the Fig. 7. In the Fig. In the example shown in Figure 13, the substrate 110 of the photolithographic mask 700 is arranged on the sample stage 1340 by means of a three-point support. The photomask 700 is held in position by the effect of gravity. The section of the diagram 1300 shows two of the three balls 1320 of the three-point support.

[0171] A deflection system 1350 is incorporated into the device 1200 between the output 1390 of the column 1220 of the SEM 1210 and the photomask 700. The deflection system 1350 comprises a magnetic deflection system 1330, which may be implemented, for example, in the form of a pair of coils or one or more permanent magnets (in the Fig. 13 not shown). In the Fig. In the example shown in Figure 13, the magnetic deflection system 1330 generates a magnetic field 1310 whose field lines are perpendicular to the paper plane and directed into the paper plane. The electrons of the electron beam 1215 are deflected by the magnetic field 1310 generated by the magnetic deflection system 1330 as they leave the column 1220, and they reach the point of impact 1322 on the photolithographic mask 700 on a curved path 1315. For example, the electrons of the electron beam 1215 reach the defect of excess material 750. The electron beam 1215 deflected by the magnetic field 1310 of the magnetic deflection system 1330 strikes the mask 700 at an angle φ1, which is smaller than the angle of impact of a non-deflected electron beam φ = 90°. The path 1315 of the electrons extended by the magnetic deflection system 1330 is taken into account when focusing the electron beam 1215.

[0172] The magnetic deflection system 1330 can generate a homogeneous or an inhomogeneous magnetic field 1310. The strength of the magnetic field 1310 can be adjusted by the adjustment unit 1290 of the computer system 1280, for example, via the strength of the current flow through the coil pair that generates the magnetic field 1310.

[0173] In the Fig. 13, the magnetic deflection system 1330 generates a homogeneous magnetic field 1310 whose field lines pass perpendicularly through the plane of the paper. However, it is also possible for the magnetic deflection system 1330 to generate a second magnetic field whose field lines run parallel to the plane of the paper, for example. With the help of two essentially perpendicular magnetic fields, the magnetic deflection system 1330 can adjust not only the polar angle of the electron beam 1215 but also its azimuth angle by changing the field strength of the two magnetic fields. This enables the electron beam 1215 to reach different sides of a pattern element 120 of a photolithographic mask 700 at the angle of incidence φ1. The magnetic deflection system 1330 can adjust the magnetic field strength, for example by changing the coil current, and thus dynamically during the analysis of the sample 1225 orthe photolithographic mask 700, adapt the angle of incidence φ1 to the defect being examined.

[0174] The magnetic deflection system 1330 is in the Fig. 13 as a separate unit 1350 from the column 1220 of the SEM 1210. However, it is also possible to integrate the magnetic deflection system 1330 into the SEM 1210 at the output of the column 1220 (in the Fig. 13 not shown).

[0175] The diagram 1400 of the Fig. 14 presents a second embodiment of a lowering system 1203, 1350. In the Fig. 14, the deflection system 1203, 1350 comprises an electrical deflection system 1430. The electrical deflection system 1430 is shown in the Fig. 14 is realized by two additional deflection plate pairs 1410 and 1420, which are installed in front of the electron-optical objective lens 1450 of the SEM 1210 in its column 1220. The first deflection plate pair 1410 deflects the electron beam 1215 from the axis 1460 or the electron-optical axis 1460 of the SEM 1210. The second deflection plate pair 1420 is designed and arranged such that the deflected electron beam 1415 essentially passes through the center of the electron-optical objective lens 1450. This beam guidance prevents the deflected electron beam 1415 from suffering significant imaging errors due to the electron-optical objective lens 1450.

[0176] The Fig. 14 shows that the electron beam 1415 deflected by the electrical deflection system 1430 impinges on the sample 1225 at an angle φ2 that is significantly reduced compared to the impingement angle of a non-deflected electron beam 1415. Furthermore, the deflected electron beam 1415 impinges on the surface 115 of the sample 1225 at a location 1422 that is different from the impingement point of a non-deflected electron beam. By varying the electrical voltages applied to the deflection plate pairs 1410 and 1420 of the electrical deflection system 1430, the impingement angle φ2 on the surface 115 of the sample 1225 can be adjusted. Furthermore, by changing the electrical voltages applied to the deflection plate pairs 1410 and 1420, the angle of incidence φ2 can be adjusted during scanning or examining the sample 1225.The adjustment unit 1290 can adjust and control the electrical deflection system 1430. The evaluation unit 1285 can determine the settings of the electrical deflection system 1430 based on the measurement data determined for a defect.

[0177] In the Fig. In the example shown in Figure 14, the electrical deflection system 1430 is designed to deflect the electron beam 1215 in one direction relative to the electron-optical axis 1460. Of course, it is also possible to design the electrical deflection system 1430 such that it can deflect the electron beam 1215 passing through the deflection system 1430 in two different directions relative to the electron-optical axis 1460 of the SEM 1210.

[0178] Furthermore, it is possible to combine a magnetic deflection system 1330 and an electrical deflection system 1430 in a deflection system 1203, 1350. The deflection systems 1330 and 1430 can be used not only for deflecting massive particles in the form of electron beams 910. Rather, these deflection systems 1340 and 1440 can also be used for deflecting ion beams.

[0179] The Fig. 15 shows a schematic section through some important components of a device 1500, with which at least some of the difficulties described above during the local processing of a sample 1525, for example, a photolithographic mask 700, can be avoided. With the device 1500, for example, a defect 750 of a photomask 700 can be corrected and a sidewall angle 170, 670 of a pattern element 120 can be adjusted. The exemplary device 1500 of the Fig. 15 comprises a modified scanning particle microscope 1210, again in the form of a scanning electron microscope (SEM) 1510. To avoid unnecessary length, the parts of the device 1500 which are the same or very similar to the device 1200 of Fig. 12 are no longer described or only very briefly. Instead, the discussion of the Fig. 12.

[0180] The sample 1525 is arranged on a sample stage 1530. The imaging elements of the column 1520 of the SEM 1510 can focus the electron beam 1515 and rasterize or scan it across the sample 1525. The electron beam 1515 of the SEM 1510 can be used to induce a particle beam-induced deposition (EBID) and / or a particle beam-induced etching (EBIE) process. Furthermore, the electron beam 1515 of the SEM 1510 can also be used to analyze the sample 1525 or a defect in the sample 1525, such as the excess material defect 750 of the photolithographic mask 700.

[0181] The backscattered electrons and secondary electrons generated by the electron beam 1515 in the interaction region 1010, 1050, 1110 of the sample 1525 are registered by the detector 1517. The detector 1517, which is arranged in the electron column 1520, is referred to as an "in-lens detector." In various embodiments, the detector 1517 can be installed in the column 1520. The detector 1517 converts the secondary electrons generated by the electron beam 1515 at the measuring point 1522 and / or the electrons backscattered by the sample 1525 into an electrical measurement signal and forwards this to an evaluation unit 1585 of a computer system 1580 of the device 1500. The detector 1517 can contain a filter or a filter system to discriminate the electrons in energy and / or solid angle (in the Fig. 15 (not shown). The detector 1517 is controlled by a setting unit 1590 of the device 1500.

[0182] The second detector 1519 of the device 1500 is designed to detect electromagnetic radiation, particularly in the X-ray range. Thus, the detector 1519 allows the analysis of the radiation generated during a processing process of the sample 1525. The detector 1519 is typically also controlled by the adjustment unit 1590.

[0183] As already explained above, the electron beam 1515 can be used not only to analyze the sample 1525 but also to induce an electron beam-induced deposition process and an EBIE process. Furthermore, the electron beam 1515 of the SEM 1510 of the device 1500 can also be used to perform an EBID process. To perform these processes, the exemplary device 1500 of the Fig. 15 has three different storage containers 1540, 1550 and 1560 for storing different precursor gases.

[0184] The first reservoir 1540 stores a precursor gas, for example, a metal carbonyl, such as chromium hexacarbonyl (Cr(CO)6), or a main group metal alkoxide, such as TEOS. With the aid of the precursor gas stored in the first reservoir 1540, for example, missing material of the photolithographic mask 700 can be deposited onto the mask in a local chemical deposition reaction. Missing material of a mask 700 can include missing absorber material, for example, chromium, missing substrate material 110, such as quartz, missing material of an OMOG mask, such as molybdenum silicide, or missing material of a multilayer structure of a reflective photomask, such as molybdenum and / or silicon.

[0185] As mentioned above in the context of Fig. As described in Figure 10, the electron beam 1515 of the SEM 1510 acts as an energy supplier to split the precursor gas stored in the first reservoir 1540 at the location where material is to be deposited on the sample 1525. This means that by the combined provision of an electron beam 1515 and a precursor gas, an EBID process is carried out for the local deposition of missing material, for example, missing material of the photomask 700. The modified SEM 1510 of the device 1500, in combination with the first reservoir 1540, forms a deposition device.

[0186] An electron beam 1515 can be focused to a spot diameter ranging from the nanometer to the subnanometer range. This allows an EBID process to locally deposit missing material with a spatial resolution in the low single-digit nanometer range. However, as in the context of Fig. 9 discussed - a small focus diameter of the electron beam 1515 with a large opening angle β.

[0187] In the in the Fig. In the device 1500 shown in Figure 15, the second reservoir 1550 stores an etching gas that enables the execution of a local electron beam-induced etching (EBIE) process. Using an electron beam-induced etching process, excess material from the sample 1525, such as the excess material 750 or the defect of excess material 750 from the surface 115 of the substrate 110 of the photolithographic mask 700, can be removed. An etching gas can comprise, for example, xenon difluoride (XeF2), a halogen, or nitrosyl chloride (NOCl). Thus, the modified SEM 1510, in conjunction with the second reservoir 1550, forms a local etching device.

[0188] The third reservoir 1560 can store an additive or additional gas, which can be added as needed to the etching gas held in the second reservoir 1550 or to the precursor gas stored in the first reservoir 1540. Alternatively, the third reservoir 1560 can store a second precursor gas or a second etching gas.

[0189] Each of the reservoirs 1540, 1550 and 1760 has in the Fig. The scanning electron microscope 1510 shown in Figure 15 has its own control valves 1542, 1552, and 1562 to control the amount of the corresponding gas supplied per unit of time, i.e., the gas flow rate at the point 1522 where the electron beam 1515 impinges on the sample 1525. The control valves 1542, 1552, and 1562 are controlled by the adjustment unit 1590. This allows the partial pressure ratios of the gas(es) supplied at the processing location 1522 for performing an EBID and / or EBIE process to be adjusted within a wide range.

[0190] Furthermore, in the exemplary SEM 1510, the Fig. 15 Each reservoir 1540, 1550 and 1560 has its own gas supply system 1545, 1555 and 1565, which ends with a nozzle 1547, 1557 and 1567 near the point of impact 1522 of the electron beam 1515 on the sample 1525.

[0191] The storage containers 1540, 1550 and 1560 can have their own temperature setting element and / or control element, which allows both cooling and heating of the respective storage containers 1540, 1550 and 1560. This allows the storage and in particular the provision of the precursor gas and / or the etching gas(es) 640 at the respective optimal temperature (in the Fig. 15 (not shown). The adjustment unit 1590 can control the temperature adjustment elements and the temperature control elements of the reservoirs 1540, 1550, 1560. During the EBID and EBIE processing operations, the temperature adjustment elements of the reservoirs 1540, 1550, and 1560 can also be used to adjust the vapor pressure of the precursor gases stored therein by selecting an appropriate temperature.

[0192] The device 1500 may include more than one reservoir 1540 for storing two or more precursor gases. Furthermore, the device 1500 may include more than one reservoir 1550 for storing two or more etching gases 640 (in the Fig. 15 not shown).

[0193] The Fig. The scanning electron microscope 1510 shown in Figure 15 is operated in a vacuum chamber 1570. To perform the EBID and EBIE processes, a negative pressure in the vacuum chamber 1570 relative to the ambient pressure is usually required. For this purpose, the SEM 1510 of the Fig. 15, a pump system 1572 for generating and maintaining a required negative pressure in the vacuum chamber 1570. When the control valves 1542, 1552 and 1562 are closed, a residual gas pressure of < 10 -4Pa. The pump system 1572 may comprise separate pump systems for the upper part of the vacuum chamber 1570 for providing the electron beam 1515 of the SEM 1510 and the lower part 1575 or the reaction chamber 1575 (in the Fig. 15 not shown).

[0194] The device 1500 includes a computer system 1580. The computer system 1580 includes a scanning unit 1582 that scans the electron beam 1515 across the sample 1525. Furthermore, the computer system 1580 includes an adjustment unit 1590 for adjusting and controlling the various parameters of the modified scanning particle microscope 1510 of the device 1500. Furthermore, the adjustment unit 1590 can control the rotation of the sample stage 1530. In particular, the adjustment unit 1590 can change one or more parameters of the electron beam 1515 and / or one or more process parameters during a machining process, such as during a repair of a defect 750 and / or during an adjustment of a sidewall angle 170, 670.

[0195] In addition, the computer system 1580 has an evaluation unit 1585, which analyzes the measurement signals from the detectors 1517 and 1519 and generates an image therefrom, which is displayed on the display 1595 of the computer system 1580. In particular, the evaluation unit 1585 is designed to determine the position and a 3D contour of a defect of missing material and / or a defect of excess material 750 of a sample 1525, such as a photolithographic mask 700, from the measurement data of the detector 1517. The evaluation unit 1585 can obtain the measurement data for performing this task via the interface 1587 of the device 1500. Based on this data, the evaluation unit 1585 can determine the parameters of a repair mold with which the identified defect 750 can be repaired.

[0196] However, it is also possible for the device 1500 to determine the measurement data itself using the electron beam 1515 and the detector(s) 1517 and 1519. In an alternative embodiment, the evaluation unit 1585 receives the position and the 3D contour of a defect 750 to be processed from the device 1200 for examining the defect 750. However, it is also possible for the evaluation unit 1585 of the device 1500 to receive the parameters of the repair shape from the device 1200 via its interface 1287.

[0197] The evaluation unit 1585 can further contain one or more algorithms that make it possible to determine a repair shape corresponding to the analyzed defect 750 of the mask 700. Furthermore, the evaluation unit 1585 of the computer system 1580 can contain one or more algorithms. The algorithm(s) can determine a change in the angle of incidence of the electron beam 1515 on the sample 1525, for example, the defect 750 of the pattern element 120 of the photomask 700, from the kinetic energy of the electrons of the particle beam 1515, a material composition to be etched or deposited, and / or the 3D contour of the defect 750.

[0198] Furthermore, algorithms of the evaluation unit 1585 can determine the parameters of a deflection system 1330, 1430, 1503. To do so, they determine a change in the angle of incidence φ of the electron beam 1515 on the sample 1525, so that the EBIE or EBID process initiated by the electron beam 1515 has an edge steepness 670 of a side wall 160 of a pattern element 120 within a predetermined range. Examples of deflection systems for the electron beam 1515 are shown in the Fig. 13 and Fig. 14. The algorithms of the evaluation unit 1585 can be implemented in hardware, software, or a combination thereof.

[0199] The evaluation unit 1585 can further be configured to determine an area and a positioning of a temporary, locally limited protective layer relative to a location to be processed from the measurement data of the detector 1519. Applying a temporary, locally limited protective layer at least partially around a local processing location can largely prevent uninvolved areas of the sample 1525, such as parts of the substrate 110 of the mask 700, from being impaired or damaged during the execution of a local processing process. The setting unit 1590 of the computer system 1580 can control both the deposition of a temporary, locally limited protective layer, for example by means of an EBID process, and its removal, for example by performing an EBIE process.In an alternative embodiment, the temporary, locally limited protective layer can be removed from the sample 1525 in a cleaning process of the sample 1525, such as a wet chemical cleaning process.

[0200] The computer system 1580 and / or the evaluation unit 1585 may include a memory, preferably a non-volatile memory (in the Fig. 15), which stores one or more models of repair shapes for different mask types. The evaluation unit 1585 can be designed to calculate a repair shape for the defects 750 of the photolithographic mask 700 from the measurement data of the detector 1517 based on a repair model. However, it is also possible for the evaluation unit 1585 to receive measurement data from the device 1200 via the interfaces 1287 and 1587 and to determine the parameters of a repair shape on the basis of this data.

[0201] As already mentioned above in the context of Fig. 12, the evaluation unit 1585, as shown in the Fig. 15, be integrated into the computer system 1580. However, it is also possible to implement the evaluation unit 1585 and / or the setting unit 1590 as independent units inside or outside the device 1500. In particular, the evaluation unit 1585 and / or the setting unit 1590 can be designed to perform part of their tasks using a dedicated hardware implementation.

[0202] Finally, the computer system 1580 may be integrated into the device 1500 or may be designed as a standalone device (in the Fig. 15). Computer system 1580 may be implemented in hardware, software, firmware, or a combination thereof.

[0203] The Fig. 16 shows a combination 1600 of devices 1200 and 1500, which can exchange data via interfaces 1287 and 1587 and connection 1650. Thus, device 1200 for examining a defect 750 in a photolithographic mask 700 can transmit measurement data of the defect 750 to device 1500 for adjusting a sidewall angle 170, 670. However, device 1200 can also transmit a determined 3D contour of defect 750 to device 1500. Furthermore, it is possible for device 1200 to transmit the parameters of a repair shape of the identified defect 750 to device 1500 via connection 1650. Furthermore, it is possible for device 1200 to be partially or entirely integrated into device 1500.

[0204] The diagram 1700 of the Fig. Figure 17 schematically presents the examination of an edge 1760 of a mask section of an EUV mask 200 with the device 1200. In a first step, which is shown in the Fig. 17 is illustrated only by the arrow 1710, the electron beam 910 scans the surface 115 of the substrate 110, the surface 215 of the multilayer structure 210, and the edge 1760. The electron beam 910 impinges perpendicularly on the surfaces 115 and 215 of the substrate 110 and the multilayer structure 210.

[0205] In a second step, the adjustment unit 1290 of the device 1200 switches on the electrical deflection system 1430 and applies an electrical voltage to the deflection plate pair(s) 1410, 1420, which were determined by the evaluation unit 1285 of the device 1200 for precisely scanning the edge 1760, which was determined from the measurement data of the first scan. The electrical deflection system 1430 deflects the electron beam 910 from the beam direction 1720, and the deflected electron beam 1730 strikes the edge 1760 of the EUV mask 200 at an incidence angle φ2 that is significantly smaller than 90°. The edge 1760 and the radii of curvature 1755 and 1765 are scanned again with the deflected electron beam 1730. The secondary electrons generated by the electron beam 1730 during scanning of the edge 1760 are in the Fig. 17 by the reference numeral 1750. The secondary electrons 1750 are used to generate an image of the edge 1760 and its surroundings by the evaluation unit 1285.

[0206] From the measurement data of the first scan (with undeflected electron beam 910) and the second scan (with deflected electron beam 1730), the evaluation unit 1285 of the device 1200 generates a realistic image of the mask section of the EUV mask 200. From this image or from the measurement data of the two scans, both the edge steepness 1770 of the edge 1760 and the radii of curvature 1755 and 1765 can be determined with great precision. If, during evaluation of the measurement data, it turns out that the selected deflection angle φ2 is not optimally suited for scanning the edge 1760, a different (smaller or larger) deflection angle φ2 can be selected, and the edge 1760 can be scanned again together with the radii of curvature. Furthermore, it is possible that the evaluation unit 1285 determines a change in the deflection angle φ2 during the scanning of the edge 1760 and the adjustment unit 1290 changes the deflection angle of the electron beam 1730.

[0207] If instead of the edge 1760 a defect 750, as in the context of the Fig. 17, is scanned, the evaluation unit 1285 of the device 1200 can determine a 3D contour of the defect 750 from the measurement data sets of two or more scans of the defect 750, wherein at least one scan is carried out with a deflected mass-carrying particle beam 1730.

[0208] In an alternative embodiment, the inspection of a defect 750 may be performed with the device 1500 for adjusting a sidewall angle 170, 670.

[0209] The flowchart 1800 of the Fig. 18 presents the steps of the method for examining at least one defect 750 of a photolithographic mask 700 with at least one massed particle beam 910. The method begins at step 1810. In the next step 1820, at least one massed particle beam 910 is provided. A massed particle beam 910 preferably comprises an electron beam 910. Then, in step 1830, an average angle of incidence φ1, φ2 of the massed particle beam 910 on at least one defect 750 is changed during the examination of the at least one defect 750. Changing the average angle of incidence φ1, φ2 can be performed using a deflection system 1203, 1330, 1430, 1503. The method ends at step 1840.

[0210] The 1900 diagram of the Fig. 19 schematically shows the etching of a depression into a sample 1910 by performing an EBIE process using the device 1500, wherein the electron beam 1930 impinges on the sample 1910 at an angle φ2 < 90°. The depression can, for example, be a line etched perpendicular to the paper plane into the sample 1910. The sample 1910 can, for example, be the substrate 110, a multilayer structure 210 and / or a pattern element 220 of an EUV mask 200. Partial image A of the Fig. Figure 19 shows the execution of an EBIE process with a deflected electron beam 1930. The etching gas 640 is in the Fig. 19 is suppressed for simplification purposes. The electron beam 910 generated by the particle beam source 1510 travels along the optical axis through the column 1520 of the SEM 1510. The electrical deflection system 1430 deflects the electron beam 1930 from the optical axis of the column 1520 so that it impinges on the surface 1915 of the sample 1910 at an angle φ2 < 90°. The mean direction of the depression generated by the EBIE process is essentially parallel to the direction of the incident electron beam 1930.

[0211] Part B of the Fig. Figure 19 shows the created depression. The two sidewall angles 1970 and 1990 created by the EBIE process are different. However, both depend on the angle of incidence φ2 of the electron beam 1930 on the sample 1910. The two radii of curvature 1925 and 1945 also have different numerical values. The created depression has a rounded portion 1935 at its lower end. To adjust the sidewall angle 1970 and / or the radius of curvature 1925, the angle of incidence φ2 of the electron beam 1930 can be changed during etching of the depression.

[0212] Part C of the Fig. Figure 19 shows the depression of partial image B which is formed after rotating the sample by 180° around the optical axis of column 1520 of the SEM 1510 or by deflecting the electron beam 910 in the opposite direction as in partial image A and widening the depression to a symmetrical depression. As can be seen from partial images A to C of the Fig. As can be seen in Figure 19, using an EBIE process that uses an electron beam 1930 whose angle of incidence φ2 on the sample surface 1915 is less than 90°, a structure can be etched into a sample 1910 whose sidewall angle 1970 can be adjusted by the angle of incidence φ2 on the sample surface 1915. Furthermore, the angle of incidence φ2 influences the radius of curvature 1925 of the transition of the etched structure to the sample surface 1915.

[0213] Part D of the Fig. Figure 19 shows the right edge of the depression in partial image B with the edge steepness 1970, after the part of the sample 1910 to the left of the depression has been etched to a predetermined depth using an EBIE process. For this etching process, the energy-delivering electron beam can impinge on the sample 1910 without deflection (i.e., as electron beam 910) or with deflection (i.e., as electron beam 1930). If the edge steepness 1970 is not within a predetermined interval and / or the radii of curvature 1925 and 1965 do not have the desired numerical values, the etched edge 1960 can be processed again using an EBIE process, with the electron beam 1930 having a different angle of incidence φ2. Of course, it is also possible to change the incidence angle φ2 of the electron beam 1930 during the etching of the recess.

[0214] The 2000 diagram of the Fig. Figure 20 illustrates the etching of an opening 2020 in a pattern element 220 arranged on a multilayer structure 210 of the EUV mask 200. To create the opening 2020, an ion beam 2010 is used—unlike previously—which is incident perpendicularly on the pattern element 220 of the EUV mask 200. Etching with an ion beam 2010 has at least two significant advantages compared to electron beam-induced etching. First, an ion beam can create the opening 2020 by performing a sputtering process. During a sputtering process, the atoms of the lattice of the pattern element 220 are essentially torn from their bonds by momentum transfer by the ions of the ion beam 2010. An etching process performed with an ion beam 2010 is therefore considerably faster than an EBIE process. Second, the ion beam 2010 can often etch the opening 2020 without providing an etching gas 640.

[0215] However, these advantages are offset by equally significant disadvantages. Firstly, the momentum transfer of the massive ions to the atoms of the pattern element 220 causes significant damage to the lattice of the pattern element 220 in the interaction region of the ions with the lattice atoms. Secondly, a significant portion of the ions is incorporated into the damaged lattice of the pattern elements 220 or into the underlying multilayer structure 210, thereby significantly altering the properties, for example, the optical properties, in the interaction region. Fig. 20, the interaction area or the damage area is illustrated by the gray scattering bulb 2030. The creation of the opening 2020 of the pattern element 220 results in the Fig. 20 results in damage to the upper - crucial - layers of the multilayer structure 220.

[0216] The diagram 2100 of the Fig. Figure 21 shows how the disadvantages of an ion beam-induced etching process can be essentially avoided by a non-perpendicular incidence of an ion beam. The ion beam 2010, which travels along the optical axis of a FIB (Focused Ion Beam) device, is deflected by a deflection system 1203, 1330, 1430, 1503 and strikes the surface 225 of the pattern element 220 as a deflected ion beam 2120 at an angle φ3 < 90°. At a flat angle of incidence φ3 << 90° of the ion beam 2120, the sputtering rate and thus the process speed reach their maximum value. In addition, a large portion of the atoms 2150 sputtered by the ion beam 2120 leave the pattern element 220. This is an additional advantage of an etching process performed with a deflected ion beam 2120. At the same time, little energy and ions from the deflected ion beam 2120 are introduced into the pattern element 220.More importantly, however, the etching or sputtering process performed with the deflected ion beam 2120 causes little damage to the multilayer structure 210 below the opening 2030. This means that the optical properties of the multilayer structure 210 are essentially unaffected by the ion beam-induced etching process.

[0217] The Fig. 22 and Fig. 23 illustrate how the Fig. 9 and Fig. 10 explained difficulties in the local examination and / or processing of a sample 1225, 1525, for example the photomask 150, 700, can be largely eliminated by reducing the average angle of incidence of the massed particle beam 1215, 1515, 1930 on the side wall 160 of the pattern element 120. The upper partial image 2205 of Fig. 22 illustrates the impingement of the electron beam 1215, 1515 1930 deflected by the angle φ2 onto the photolithographic mask 150. Exemplary devices for deflecting the electron beam 1215, 1515, 1930 are described in the context of Fig. 13 and Fig. 14 explained.

[0218] The lower part of the image 2255 of the Fig. 22 presents the intensity distribution of the deflected electron beam 1215, 1515, 1930 in its focus 1940. As in the Fig. 22, by reducing the average angle of incidence of the electron beam 1215, 1515, 1930 410 on the side wall 160 of the photolithographic mask 150, 700, the electron beam 1215, 1515, 1930 can be focused at the focal point to a small spot diameter 1980, without the resulting large aperture angle β being significantly shadowed by the pattern element 120 of the photomask 150, 700.

[0219] The Fig. 23 presents interaction regions 2310, 2350 of the electron beam 1215, 1515, 1930 during examination and / or processing, for example, during etching of the side wall 160 of the photolithographic mask 150, 700, wherein the average angle of incidence φ2 of the electron beam 1215, 1515, 1930 on the side wall 160, as indicated in partial image 2205, is less than 90°. The problems of examination and / or processing of the side wall 160 with a non-deflected electron beam have already been discussed in the context of Fig. 10. Unlike in the Fig. 10, when examining and / or processing the sidewall 160 with the incident angle φ2 < 90°, the interaction region 2350 is hardly deformed. This means, for example, that the sidewall 160 can be scanned with the electron beam 1215, 1515, 1930 without the interaction regions 2310 and 2350 causing damage to the substrate 110 of the photomask 150.

[0220] Furthermore, the side wall 160 can be processed with the deflected electron beam 1215, 1515, 1930, for example etched by means of an EBIE process, wherein the edge steepness 170 can be adjusted in the manner shown in the Fig. 23 is not significantly changed. However, this is a consequence of the specifically selected angle of incidence φ2. Furthermore, neither the angle of incidence φ2 nor a process parameter was changed during the etching process. By changing the angle of incidence φ2 and / or a process parameter, the edge steepness 170 can be changed, as in the context of Fig. 19. Another advantage of a deflected electron beam 1215, 1515, 1930 is that the surface 115 of the substrate 110 is not noticeably attacked during the local etching process.

[0221] The diagram 2400 of the Fig. 24 presents the correction of a defect of missing material by depositing material 2420 along the sidewall 160 of the pattern element 120 onto the substrate 110 of the photolithographic mask 150. Unlike when performing the process shown in the Fig. 11, the average angle of incidence of the mass-bearing particle beam 1930 φ2 < 90° on the surface 115, 125, 160 of the photomask 150 was set before the start of the process - similar to the Fig. 22 and Fig. 23 - reduced. The Fig. 24 that the deposit 2420 is deposited with a sidewall 2460 and an edge steepness 2470 that deviates from the angle of 90° specified by the design of the photomask 150. The edge steepness 2470 of the generated sidewall 2460 can be adjusted by selecting the angle of incidence φ2 and in particular by changing it during the deposition process. If necessary, one or more process parameters can also be changed during the deposition process. In addition, the radius of curvature 2475 of the generated sidewall 2460 is not significantly larger than that of a defect-free pattern element 120 of the photomask 150. Moreover, the deposited in the Fig. 24, the deposition process essentially leaves no material 2420 on the surface 115 of the substrate 110 of the photolithographic mask 150.

[0222] The diagram 2500 of the Fig. 25 shows the correction of a defect 2550 adjacent to a pattern element 2500 of a photomask according to a prior art method. The pattern element 2510 can be arranged, for example, on a substrate 110 of a mask 150 or on a multilayer structure 220 of an EUV mask 200. The defect 2550 is repaired using an EBIE process. A top view of a repair mold 2520, which is used to correct the defect 2550, is arranged below the defect 2550. The gray-shaded areas 2530, 2535, and 2540 represent the areas exposed by the repair mold 2520 during the etching process of the defect above the defect 2550. This means that by rasterizing the repair mold 2520 over the defect 2550, this successively exposes the gray-shaded areas 2530, 2535, and 2540 of the defect 2550.

[0223] When exposing or scanning the defect 2550, as specified by the repair mold 2520, an etching gas 640, for example xenon difluoride (XeF2) or generally a halogen-containing gas, is provided over the defect 2550 (in the Fig. 25 not shown). The process parameters, such as the repetition time, i.e. the time period until the electron beam 910 returns to the same point within the repair shape, the dwell time, i.e. the length of time the electron beam 910 stays on a grid point, the spacing of the individual grid points, and the acceleration voltage of the electrons of the electron beam 910, are determined before the EBIE process is carried out. The area 2530 indicates the first scan of the repair shape 2520 over the defect 2550. The area 2535 indicates a scan of the repair shape over the defect 2550 approximately halfway through the etching time for removing the defect 2550. Halfway through the defect 2550 can, for example, be reached after several thousand executions of the repair shape 2520 over the defect 2550. The area 2540 describes the execution of the repair shape 2520 at the end of the etching process. Time is running out in the example of Fig. 25 from top to bottom. As can be seen from the exposed areas 2530, 2535, and 2540, the area exposed by the repair mold 2520 does not change during the etching process.

[0224] Curve 2560 specifies an etch profile in the x- and z-directions of the newly formed sidewall of pattern element 2510 by the etching process. The etch profile resulting at edge 2580 generates an edge steepness 2570 or a sidewall angle 2570, which is determined by the repair shape 2520 and the process parameters. The edge steepness 2570 has an angle that is significantly smaller than a design-specified angle of 90°.

[0225] The diagram 2600 of the Fig. 26 gives again the initial situation of the Fig. 25 with the defect 2550 adjacent to a pattern element 2510. Unlike in the Fig. 25 will be in the Fig. 26, however, the area of ​​the defect 2550 exposed by the repair mold 2620 increases during the etching process, ie with increasing number of defect exposures 2630, 2635 and 2640 by the electron beam 910. This is shown in the Fig. 26 is illustrated by the arrows 2605 and 2615. This dynamic change of the exposed area from 2630 to 2640 leads to the etch profile 2660 at the edge 2680 of the forming sidewall of the pattern element 2510. By dynamically increasing the area exposed by the repair shape 2620, the edge steepness 2670 of the sidewall of the pattern element 2510 forming in the etching process increases. This means that by dynamically changing the repair shape 2620, the sidewall angle 2570 of the newly formed sidewall can be adjusted.

[0226] Instead of or in addition to changing the repair shape 2620, one or more process parameters of the EBIE process may be changed during the execution of the etching process (in the Fig. 26 not shown).

[0227] Diagram 2700 of the Fig. Figure 27 presents, in the upper part of image A, a substrate 2710 of a photomask into which a recess 2720 was again etched using an EBIE process. The recess 2720 was subsequently filled by depositing a metal 2730. During the etching of the recess 2720, the electron beam 910 had an asymmetric beam profile. Fig. 27, the two white, subsequently added lines indicate the edge steepnesses 2770, 2780 of the depression 2720. As can be seen from the partial image A of the Fig. As can be seen from Figure 27, the asymmetric beam profile of the electron beam 910 translates into a left sidewall angle of 2770 and a right sidewall angle of 2780, which have different numerical values.

[0228] The lower part B of the Fig. Figure 27 shows the etching of a recess 2750, where the asymmetry of the beam profile was swapped by 180°. Fig. 27 illustrates that by changing one or more parameters of the massed particle beam 910, a depression with adjustable sidewall angles 2770, 2780 can be generated.

[0229] Finally, the flowchart 2800 presents the Fig.28 the steps of the method for setting at least one sidewall angle 170, 670, 1970, 2470, 2770, 2780 of a pattern element 120, 220, 230, 250, 260, 280, 290, of a photolithographic mask 150, 200, 700. The method begins at step 2810. In the next step 2820, at least one precursor gas is provided. One or more precursor gases can be stored in one of the reservoirs 1540, 1550, 1560 of the device 1500 and can be guided by means of a gas line system 1545, 1555, 1565 to the location where the massed particle beam 910, 1215, 1515, 1930 impinges on a sample 1225, 1525.

[0230] Then, in step 2830, at least one mass-carrying particle beam 910, 1215, 1515, 1930, 2120 is provided, which excites a local chemical reaction of the at least one precursor gas. In step 2840, at least one parameter of the particle beam and / or a process parameter is changed during the local chemical reaction to adjust the at least one sidewall angle 170, 670, 1970, 2470, 2770, 2780 of the at least one pattern element. The method ends in step 2850.

Claims

[1] Method (2800) for setting at least one sidewall angle (170, 670, 1970, 2470, 2770, 2780) of at least one pattern element (120, 220, 230, 250, 260, 280, 290) of a photolithographic mask (150, 200, 700), the method comprising the steps of: a. Providing at least one precursor gas; b. Providing at least one mass-bearing particle beam (910, 1215, 1515, 1930, 2120) which excites a local chemical reaction of the at least one precursor gas; c. Changing at least one parameter of the particle beam (910, 1215, 1515, 1930, 2120) and / or a process parameter during the local chemical reaction to adjust the at least one sidewall angle (170, 670, 1970, 2470, 2770, 2780) of the at least one pattern element (120, 220, 230, 250, 260, 280, 290); and d. Changing a size of a repair shape (2620) in one dimension from the start to the end of the local chemical reaction by at least 5% relative to a process resolution limit in one dimension. [2] Method (2800) according to the preceding claim, wherein the at least one mass-bearing particle beam (910, 1215, 1515, 1930, 2120) excites the local chemical reaction at the location of the sidewall angle (170, 670, 1970, 2470, 2770, 2780) to be set. [3] Method (2800) according to one of the preceding claims, wherein the adjustment of the at least one sidewall angle (170, 670, 1970, 2470, 2770, 2780) occurs during a defect repair of the photolithographic mask (150, 200, 700). [4] Method (2800) according to one of the preceding claims, wherein changing at least one parameter of the at least one particle beam (910, 1215, 1515, 1930, 2120) comprises changing at least one element from the group: - a centrosymmetric adjustment of at least one condenser diaphragm of an imaging system (1213, 1513) of at least one particle beam source (1205, 1505) with respect to an optical axis of the mass-bearing particle beam (910, 1215, 1515, 1930, 2120), - a non-circular setting of at least one aperture of the imaging system (1213, 1513) of the at least one particle beam source (1205, 1505), - an adjustment of the imaging system (1213, 1513) of the at least one particle beam source (1205, 1505) for tilting the massed particle beam (910, 1215, 1515, 1930, 2120) with respect to a normal of a patterned surface of the photolithographic mask (150, 200, 700), - an adjustment of a deflection system (1350) for tilting the massed particle beam (910, 1215, 1515, 1930, 2120) with respect to the normal of the patterned surface of the photolithographic mask (150, 200, 700), and - an adjustment of a beam profile of the massive particle beam (910, 1215, 1515, 1930, 2120) during the local chemical reaction. [5] Method (2800) according to one of the preceding claims, wherein changing the at least one process parameter comprises at least one element from the group: - dividing a repair form (2520, 2620) into at least two partial repair forms for processing the at least two partial repair forms with different process parameters, - Changing at least one parameter from the group: a repetition time, a dwell time, a distance between adjacent grid points of the mass-carrying particle beam (910, 1215, 1515, 1930, 2120) and an electrical acceleration voltage of the at least one mass-carrying particle beam (910, 1215, 1515, 1930, 2120) during the local chemical reaction, - changing a size of the repair shape (2620) during the local chemical reaction; and - Changing a position of the repair form (2520, 2620) during the local chemical reaction. [6] The method (2800) of any preceding claim, wherein the size of a repair shape (2620) in one dimension changes from the beginning to the end of the local chemical reaction by at least 30% relative to a process resolution limit in one dimension. [7] The method (2800) of any preceding claim, wherein the position of an edge of a repair shape (2520, 2620) changes from the beginning to the end of the local chemical reaction by at least 5% relative to a process resolution limit in one dimension. [8] Method (2800) according to one of the preceding claims, further comprising the steps of: a. interrupting the local chemical reaction; and b. Examining a defect residue of the at least one defect (750) and / or a sidewall (2460) generated during the local chemical reaction. [9] Method (2800) according to the preceding claim, further comprising the steps of: c. Changing at least one parameter of the particle beam (910, 1215, 1515, 1930, 2120) and / or a process parameter that has not been changed so far during the local chemical reaction, if the defect residue being examined and / or the sidewall (2460) generated so require; and d. Continuing the local chemical reaction with the at least one changed parameter or continuing the local chemical reaction with the unchanged parameters if the examined defect residue and / or the generated sidewall (2460) do not require this. [10] Method (1800) for examining at least one defect (750) of a photolithographic mask (150, 200, 700) with at least one massed particle beam (910, 1215, 1515, 1930, 2120), the method comprising the steps of: a. Providing at least one mass-bearing particle beam (910, 1215, 1515, 1930, 2120); and b. Changing an average angle of incidence (φ1, φ2, φ3) of the massed particle beam (910, 1215, 1515, 1930, 2120) on the at least one defect (750) during the examination of the at least one defect (750). [11] Method (1800) according to the preceding claim, wherein the at least one defect (750) comprises at least one element from the group: - missing material of a pattern element (120, 220, 230, 250, 260, 280, 290), - excess material of a pattern element (120, 220, 230, 250, 260, 280, 290), - missing material of a substrate (110) of the photolithographic mask (150, 200, 700), - excess material of the substrate (110) of the photolithographic mask (150, 200, 700), a sidewall angle (170, 670, 1970, 2470, 2770, 2780) outside a predetermined range, - missing material of an element on a NIL substrate and / or a NIL template, - excess material of an element on a NIL substrate and / or a NIL template, - a sidewall angle (170, 670, 1970, 2470, 2770, 2780) outside a specified range, - a radius of curvature (1935, 1945) of a side wall (1960) of the at least one pattern element (170, 670, 1970, 2470, 2770, 2780) to its surface, which is outside a predetermined range, and - a radius of curvature (1935, 1945) of the side wall (1960) of the at least one pattern element (170, 670, 1970, 2470, 2770, 2780) to the substrate (110) of the photolithographic mask (150, 200, 700) which is outside a predetermined range. [12] The method (1800) of claim 10 or 11, wherein changing the mean angle of incidence (φ1, φ2, φ3) of the at least one mass-carrying particle beam (910, 1215, 1515, 1930, 2120) comprises: deflecting the mass-carrying particle beam (910, 1215, 1515, 1930, 2120) in an electric field and / or in a magnetic field. [13] The method (1800) of any of claims 10-12, further comprising the step of: determining parameters of a repair shape (2520, 2620) for the at least one defect (750) under investigation. [14] Method (1800) according to one of claims 10-13, wherein changing the average angle of incidence (φ1, φ2, φ3) comprises: changing the angle of incidence by > 5° relative to a normal incidence of the at least one mass-bearing particle beam (910, 1215, 1515, 1930, 2120) onto a substrate (110) of the photolithographic mask (150, 200, 700). [15] A computer program comprising instructions which, when executed by a computer system, cause the computer system to carry out the method steps of any one of claims 1 to 9. [16] A computer program comprising instructions which, when executed by a computer system, cause the computer system to carry out the method steps of any one of claims 10 to 14. [17] Device (1500) for adjusting at least one side wall angle (170, 670, 1970, 2470, 2770, 2780) of at least one pattern element (170, 670, 1970, 2470, 2770, 2780) of a photolithographic mask (160, 200, 700), comprising: a. at least one gas supply system (1540, 1542, 1545, 1547, 1550, 1552, 1555, 1547, 1560, 1562, 1565, 1567) configured to provide at least one precursor gas; b. at least one particle beam source (1205, 1505) configured to generate at least one mass-carrying particle beam (910, 1215, 1515, 1930, 2120), wherein the at least one mass-carrying particle beam (910, 1215, 1515, 1930, 2120) is configured to excite the at least one precursor gas to a local chemical reaction; and c. at least one adjustment unit (1590) which is designed to change at least one parameter of the at least one particle beam source (1205, 1505) and / or at least one process parameter during the local chemical reaction for adjusting the at least one sidewall angle (170, 670, 1970, 2470, 2770, 2780) of the at least one pattern element (120, 220, 230, 250, 260, 280, 290); d. wherein the adjustment unit (1590) is further configured to change a size of a repair shape (2620) in one dimension from the beginning to the end of the local chemical reaction by at least 5% relative to a process resolution limit in one dimension. [18] Device (1500) according to the preceding claim, wherein the setting unit (1590) is further configured to receive at least one element from the group: - measurement data of at least one defect (750) recorded at different angles of incidence (φ1, φ2, φ3), - data of a three-dimensional contour of at least one defect (750), - parameters of a repair form (2520, 2620) of at least one defect (750), - data of a defect residue of at least one defect (750), - a side wall angle (170, 670, 1970, 2470, 2770, 2780) of at least one pattern element (120, 220, 230, 250, 260, 280, 290), and - an angle of a generated side wall (2460). [19] Device (1200) for examining at least one defect (750) of a photolithographic mask (150, 200, 750) with at least one massed particle beam (910, 1215, 1515, 1930, 2120) at different angles, comprising: a. at least one particle beam source (1205) configured to generate at least one mass-bearing particle beam (910, 1215, 1515, 1930, 2120); and b. at least one adjustment unit (1290) designed to change an average angle of incidence (φ1, φ2, φ3) of the mass-bearing particle beam (910, 1215, 1515, 1930, 2120) during the examination. [20] Device (1200) according to the preceding claim, wherein the adjustment unit (1290) is further configured to control the changing of the mean angle of incidence (φ1, φ2, φ3) of the massed particle beam (910, 1215, 1515, 1930, 2120) on the at least one pattern element (120, 220, 230, 250, 260, 280, 290) of the photolithographic mask (150, 200, 700) on the basis of a parameterized repair shape (2520, 2620).

Images