METHOD AND COMPUTER PROGRAM FOR MACHINING A SURFACE OF AN OBJECT

Abstract

A method for processing a surface (120) of an object, comprising: a. supplying a gas mixture comprising at least a first gas (150) and a second gas (160) to a reaction site (110) on the surface (120) of the object; b. Inducing a reaction, which includes at least a first partial reaction and a second partial reaction, at the reaction site (110) by exposing the reaction site (110) to a beam of energetic particles (115) in a plurality of exposure intervals, wherein b1. the first partial reaction is predominantly mediated by the first gas (150) and the second partial reaction is predominantly mediated by the second gas (160), and wherein b2. there is a gas refresh interval between the respective exposure intervals; c. Setting a first time period for the gas refresh interval, whereby a process rate of the first partial reaction and a process rate of the second partial reaction are present; d. Setting a second time period for the gas refresh interval which causes a relative increase in the process rate of the first partial reaction compared to the process rate of the second partial reaction.

Description

1. Technical area

[0001] The present invention relates to a method, a device and a computer program for processing a surface of an object, in particular a surface of a lithographic mask, for example for repairing one or more defects in such a mask. 2. State of the art

[0002] As a result of the ever-increasing integration density in microelectronics, lithographic masks, often simply called masks, must image ever smaller structural elements into a wafer photoresist layer. To meet these requirements, the exposure wavelength is being shifted to ever shorter wavelengths. Currently, argon fluoride (ArF) excimer lasers, which emit light at a wavelength of 193 nm, are mainly used for exposure purposes. Intensive work is being carried out on light sources that emit in the extreme ultraviolet (EUV) wavelength range (10 nm to 15 nm) and corresponding EUV masks. To increase the resolution of wafer exposure processes, several variants of conventional binary lithographic masks have been developed simultaneously. Examples of these are phase masks or phase-shifting masks and masks for multiple exposure.

[0003] However, due to the ever-shrinking dimensions of the structural elements, lithographic masks cannot always be manufactured without visible or printable defects on a wafer. Due to the costly production of masks, defective masks are repaired whenever possible.

[0004] Two important groups of defects in lithographic masks are dark defects and clear defects.

[0005] Dark defects are areas where absorber or phase-shifting material is present, but should be free of this material. These defects are repaired by removing the excess material, preferably using a local etching process.

[0006] Clear defects, on the other hand, are defects on the mask that exhibit greater light transmission than an identical defect-free reference position upon optical exposure in a wafer stepper or wafer scanner. In mask repair processes, such clear defects can be repaired by depositing a material with suitable optical properties. Ideally, the optical properties of the material used for the repair, and especially those of the material created by the repair, should match those of the absorber or phase-shifting material of the mask.

[0007] A possible method for mask repair is described, for example, in document WO 2009 / 106288 A2.

[0008] US 2006 / 0 099 519 A1 relates to controlling the attenuation and phase of light transmitted through a deposited material, which is particularly suitable for repairing attenuated phase-shift photomasks. The transmission and phase of the repaired area can be controlled. In a preferred embodiment, the phase of the light transmitted through the repaired area is controlled by controlling the thickness of a deposited material, and the transmittance of the repaired area is controlled by controlling the introduction of an impurity into the repair area.

[0009] EP 0 571 727 A1 relates to a method and structure for controlling the deposition of material induced by a focused ion beam. The structure comprises a focused ion beam directed onto a target surface. The ion beam is deflected to locations on the target surface and gated and ungated at desired intervals. The deflection and gated actions are controlled by timers in response to computer signals. A precursor gas is adsorbed onto the target surface, and the ion beam selectively decomposes the adsorbed gas along a desired shape to enable material deposition. The shape of the deposition is determined by a series of consecutive beam spots. The spots can be chosen to overlap with adjacent spots to achieve better edge resolution, but generally, optimal yield is achieved without overlap.The dwell time for each spot is adjusted to achieve a high net yield of deposited material. The beam is guided stepwise to each position in the mold, and the deposition is repeated. Alternatively, the beam could be moved between spots in successive line scans, either stepwise or continuously, but point-by-point sweeping allows for greater control of the feature shape. After all points of the pattern are completed, the process is repeated until a layer of material of the desired thickness is created.

[0010] US 2010 / 0 224 592 A1 relates to electron beam-induced chemical reactions with precursor gases, which are controlled by controlling adsorbate depletion. Adsorbate depletion can be controlled by controlling the beam current, preferably by rapidly blanking the beam, and by cooling the substrate. The beam preferably has a low energy to reduce the interaction volume. By controlling the depletion and interaction volume, the user can produce precise shapes.

[0011] EP 1 664 924 B1 relates to a method for etching a chromium layer in a vacuum chamber, comprising the steps of introducing a halogen compound into the vacuum chamber, directing an electron beam onto the area of ​​the chromium layer to be etched, and introducing an oxygen-containing compound into the vacuum chamber.According to a further aspect, a further method for the high-resolution removal of a layer of metal and / or metal oxide arranged on an insulator or a substrate with poor thermal conductivity relates to the method steps of arranging the layer within a vacuum chamber, bombarding the layer with a focused electron beam with an energy of 3-30 keV, wherein the electron beam is guided such that the energy transfer per time and area causes a local heating of the layer above its melting and / or evaporation point and wherein the removal of the layer takes place without supplying reaction gases into the vacuum chamber.

[0012] US 5,683,547 A relates to a focused energy beam machining method and apparatus for performing local energy beam machining in a focused energy beam irradiation region by irradiating a sample with a focused energy beam such as an ion beam or an electron beam in an etching gas atmosphere. A mixed gas different in composition from any conventional gas is used as the etching gas, and the gas is uniformly supplied to an etching region, and at least one of the components of such a mixed gas is a spontaneously reactive gas for use in spontaneously and isotropically etching the sample. With this arrangement, it is possible to subject a material to local etching for which local etching was not possible because a single etching gas causes too vigorous a reaction or almost no reaction.

[0013] However, both in the production and subsequent processing of modern masks, particularly in mask repair, a number of partial reactions often play a role, each of which is primarily induced or mediated by a specific reaction gas. Due to structural and cycle-time limitations, known devices and methods use a gas mixture containing the various reaction gases in proportion. These gases then diffuse to the reaction site and adsorb onto the surface of the mask. By irradiating the mask with an energetic particle beam, the adsorbed gas molecules can be "activated," triggering the partial reaction they mediate.Furthermore, this may apply not only to the processing of lithographic masks, but more generally to the surface processing of objects in the field of microelectronics, for example when modifying and / or repairing structured wafer surfaces or microchips or the like.

[0014] Since, as mentioned, gas mixtures are traditionally used, the individual partial reactions essentially occur in parallel. Therefore, it has not been possible to date, or only with significantly increased effort, to selectively optimize the exposure settings and other process parameters during object / mask processing for one of the sub-processes without potentially negatively impacting the other sub-processes.

[0015] The present invention is therefore based on the object of providing a method that allows a sub-process to be selectively "picked out" during surface processing, in particular mask processing, and to be "reinforced" over other sub-processes in order to specifically optimize the exposure and process parameters for this sub-process, without requiring the respective reaction gases to be introduced one after the other and then completely pumped out again before the next sub-process is carried out. Furthermore, a corresponding device and a computer program with instructions for carrying out such a method are to be provided. 3. Summary of the invention

[0016] The above objects are at least partially achieved by the various aspects of the present invention as described below.

[0017] In one embodiment, a method for processing a surface of an object comprises the following steps: (a.) supplying a gas mixture comprising at least a first gas and a second gas to a reaction site on the surface of the object; (b.) inducing a (chemical) reaction, which comprises at least a first partial reaction and a second partial reaction, at the reaction site by exposing the reaction site to a beam of energetic particles in a plurality of exposure intervals, wherein the first partial reaction is predominantly mediated by the first gas and the second partial reaction is predominantly mediated by the second gas, and wherein a gas refresh interval lies between the respective exposure intervals; (c.) selecting the first partial reaction in order to increase its process rate relative to a process rate of the second partial reaction; and (d.) Selecting a time duration for the gas refresh interval which causes the relative increase in the process rate of the first partial reaction compared to the process rate of the second partial reaction.

[0018] As already mentioned at the beginning, the object whose surface is to be processed may in particular comprise a lithographic mask or be formed as such. However, the scope of application of the disclosed teaching is not limited thereto, but the disclosed teaching can also be used for the surface processing of other objects used in the field of microelectronics, for example for the modification and / or repair of structured wafer surfaces or of the surfaces of microchips, etc. Nevertheless, in the following, the application case of processing a mask surface will mainly be referred to in order to keep the description clear and easy to understand. However, the other possible applications are always included, unless explicitly excluded or physically / technically impossible.

[0019] The disclosed method aims at processing the mask (or more generally the microelectronic object) at or near one of its surfaces. For this purpose, a gas mixture is supplied to the reaction site, i.e. the site at which the processing (e.g., material removal or material deposition) is to take place. While the processing therefore takes place at the boundary region of the surface, it is quite possible that the reaction site also extends several atomic layers deep into the mask and therefore does not lie exclusively “on” the surface (in the mathematically strict sense of a two-dimensional area). The atoms / molecules contained in the gas mixture can, for example, penetrate a certain depth into the mask material and be caused to react there. In other words, the “reaction site at a surface of the mask” includes both a purely superficial processing site and a processing site with a certain depth (e.g.,a few atomic layers deep, as described above).

[0020] The processing method involves a reaction with (at least) two partial reactions or sub-processes, for example an etching and a passivation process or similar (more on this below). The reaction or sub-reactions can in particular be a chemical reaction or chemical reactions. Each of the partial reactions is predominantly mediated by one of the two gases contained in the gas mixture. By "predominantly" it can be meant that without the corresponding gas the partial reaction will not take place, at least not to a noticeable extent, whereas if the gas is present at the reaction site at a certain minimum concentration, the partial reaction can proceed.

[0021] In principle, other gases and / or other substances can also participate in a corresponding partial reaction, but the main contribution to the corresponding partial reaction is made by the first or second gas. Furthermore, it is also conceivable that the first and / or second gas itself contains a mixture of different partial gases. For the sake of simplicity and clarity, however, we will always refer to "the first gas" and "the second gas" below, and the case that each actually involves only a single gas is expressly possible. Specific examples of which gases and partial reactions can be involved are discussed further below.

[0022] To carry out or induce the (chemical) reaction with the partial reactions contained therein, the reaction site to which the two gases have been directed is exposed to a beam of energetic particles (e.g. photons, electrons or ions) in several exposure intervals.

[0023] In the context of the present disclosure, a reaction site can be understood as a pixel or, more generally, a spatial unit at which the processing can be carried out in a locally limited manner by exposure and inducing the reaction or the respective partial reaction(s). The spatial extent of the reaction site can therefore depend, for example, on the type of particle beam used, its focusing, the type of reaction, etc.

[0024] The disclosed method may, as further described below, further comprise the processing of multiple reaction sites (i.e., multiple pixels or such spatial units) in one or more exposure cycles, e.g., along a specific scan pattern (within which individual reaction sites may also occur multiple times) (more details on the term scan pattern below). However, "the reaction site" as used here and in the following always refers to a fixed location (unless otherwise stated or the context indicates otherwise).

[0025] An exposure interval can comprise a single, continuous exposure of the reaction site. However, a sequence of rapidly successive exposure flashes within an exposure interval would also be possible, provided that such an exposure event can still be regarded and described with a good approximation as a temporal unit (e.g., if the durations and / or intervals of the exposure flashes are many times shorter than the quantities relevant to the gas deposition process and the partial reactions, and thus the stepwise exposure is "not noticed" by the gas deposition dynamics and the partial reactions at the reaction site).

[0026] A gas refresh interval occurs between each exposure interval. Since after exposure of the reaction site and the completion of the first and / or second partial reaction in an exposure interval, the gas primarily mediating this reaction is at least partially used up and therefore can no longer be present in sufficient quantity and concentration at the reaction site, the gas refresh interval serves to redirect the corresponding gas to the reaction site, thus enabling a renewed induction of the associated partial reaction in the next exposure interval.

[0027] At this point, the disclosed method intervenes and deliberately selects one of the two partial reactions in order to, as described below, increase its process rate relative to the process rate of the other partial reaction. For simplicity, the following considers the case where the first partial reaction is selected. It could also be the second partial reaction; in this case, the names of the two partial reactions would simply have to be swapped, and the following statements would still apply.

[0028] By relatively increasing the process rate of the selected partial reaction, it is possible to specifically "pick out" this partial reaction and thus, for example, to specifically align the other process parameters, such as the exposure parameters (more details below), to this partial reaction. At a later stage of mask processing, the gas refresh interval can then be changed (again), for example, so that the second partial reaction takes center stage, and then the process parameters can be adjusted to this partial reaction.

[0029] It should be noted at this point that an increase in the process rate of the first partial reaction relative to the process rate of the second partial reaction does not necessarily mean that the process rate of the first partial reaction is then greater in absolute terms than that of the second partial reaction—although this possibility explicitly exists. However, the ratio of the two process rates definitely changes in favor of the first partial reaction.

[0030] How the process rate is to be quantified can depend on the type of processes / sub-reactions involved and / or the surface treatment performed. In general, the process rate can be viewed as the "speed" at which the respective sub-reaction proceeds.

[0031] For an etching / ablation process or a deposition process, the process rate can be quantified, for example, as the (instantaneous or average) material height removed or deposited per exposure interval. A typical order of magnitude for a process rate in this case can be approximately 1 nm - 150 nm per 1000 complete exposure intervals (e.g., assuming a constant interval duration).

[0032] For a passivation or activation process involving surface modification (e.g., oxidation of the surface to passivate it), the process rate can be quantified, for example, by a measure of the surface coverage already achieved. If a passivation process involves, for example, oxidation of the surface, the process rate could be defined as the percentage decrease in the unsaturated bonds at the site to be treated per process pass / exposure interval.

[0033] The person skilled in the art will therefore understand that even if a different quantitative measure of the process rate is used for the different processes / partial reactions, the relative changes in the respective process rates (e.g. expressed in % per exposure interval or per n exposure intervals, e.g. with n = 10, 100 or 1000, etc.) can be compared with one another, and it can thus be determined whether the process rate of the first partial reaction has been increased relative to the process rate of the second partial reaction.

[0034] This change in process rates does not occur by supplying the two gases separately to the reaction site and then sucking them away again, or something similar. Rather, the relative change in process rates occurs through a suitable selection of the gas refreshment interval, i.e., the time period that elapses between two exposure intervals at the reaction site. As already mentioned, the two gases mediating the partial reactions are largely consumed, or at least to a certain extent, during an exposure interval, i.e., they are depleted at the reaction site after the exposure interval. A certain residual amount may remain at the reaction site, but this will generally be insufficient to adequately mediate the corresponding partial reaction in the next exposure interval. Except in a few exceptional cases, the first gas and the second gas will also have different physical properties (e.g.,different diffusion and adsorption properties), which the disclosed method now makes use of: By a suitable selection or change of the duration of the gas refreshment interval, the refreshment process can be shifted in favor of the first gas due to the different deposition dynamics of the two gases, whereby the process rate of the first partial reaction is relatively increased.

[0035] While the relative increase in the process rate of the first partial reaction can be supported by additional measures, such as changing the proportions of both gases in the gas mixture in favor of the first gas, this is not absolutely necessary to achieve a relative increase in the process rate of the first partial reaction, which represents a particular advantage of the invention.

[0036] For example, the first gas can have a first attachment time at the reaction site and the second gas a second attachment time that is longer than the first attachment time, and the time for the gas refreshment interval can be selected such that it is shorter than the second attachment time. The term "attachment time" can, for example, be understood as the (hypothetical) time after an exposure event / exposure interval at a specific point or location, in particular the reaction site, after which the corresponding gas would be replaced there and would again be present at the same level as before the exposure. In the case considered here, the first gas is a "fast" gas, while the second gas is "slower". By selecting the time for the gas refreshment interval to be shorter than the second attachment time (but e.g., longer than or equal to the first attachment time, or merely slightly shorter than the first attachment time, e.g.,greater than or equal to 50%, or 75%, of the first accumulation time) it can thus be achieved that the first gas has already returned to the reaction site to a noticeable extent, while the second gas is still "on its way there".

[0037] The deposition times for possible gases, as described below, can be determined experimentally, for example - possibly depending on the different types of processes for which a given gas can be used and / or depending on the type and nature of the object surface to be treated - and can be used as input parameters for the process.

[0038] From a theoretical perspective, a comprehensive and generally valid description of the processes involved in such processes is difficult. Some details can be found in the article by Ivo Utke et al., "Resolution in focused electron- and ionbeam induced processing," DOI: 10.1116 / 1.2789441, J. Vac. Sci. Technol. B, Vol. 25, No. 6, Nov / Dec 2007, which is incorporated herein by reference.

[0039] However, with some generality, it can be said that at least the adsorption of the affected gas at the surface from the gas phase, as well as the diffusion along the surface of gas molecules from surrounding areas of the surface, will influence the deposition time. If K and D denote the adsorption and diffusion coefficients, respectively, with respect to these processes, the deposition time can be expressed (in a first approximation) as inversely proportional to the sum of these values: τ ~ (K + D) -1 .

[0040] If direct adsorption is negligible as a contribution to reattachment, ie reattachment depends primarily on the diffusion coefficient, which is quite possible, then (approximately) it would be: τ ~ D -1 .

[0041] Clearly, the deposition times are averages, and the diffusion and adsorption processes are stochastic in nature, so that after the gas refreshment interval has elapsed, a certain amount of the second gas will usually already be present at the reaction site. Relatively speaking, however, the first gas, and thus the first partial reaction, is favored, thus increasing its process rate.

[0042] The duration of the gas refresh interval can in particular be selected such that a concentration of the first gas diffused to the reaction site during the gas refresh interval and adsorbed there on the mask surface is higher than a concentration of the second gas.

[0043] As already mentioned, the disclosed method generally aims initially only at a relative increase in the process rate of the first partial reaction compared to the second partial reaction. Depending on the gases used, the duration of the gas refresh interval can also be selected such that the concentration of the first gas at the reaction site actually exceeds that of the second gas after the gas refresh interval has elapsed. The process rate of the first partial reaction can then also be greater in absolute terms than that of the second partial reaction.

[0044] It should also be noted, however, that a higher concentration of the first gas at the reaction site during irradiation is not always a necessary condition for the process rate of the first partial reaction to be higher, in absolute terms, than that of the second partial reaction. Other factors such as the type and nature of the partial reactions, the irradiation intensity, etc., may also play a role.

[0045] Based on the time selected in step (d), shortening the gas refresh interval can lead to a further relative increase in the process rate of the first partial reaction compared to the process rate of the second partial reaction, particularly if the first gas, as described above, is a "fast" gas compared to the second gas. Conversely, lengthening the gas refresh interval can lead to a relative reduction in the process rate of the first partial reaction compared to the process rate of the second partial reaction, because the "slower" gas then catches up and the reaction it mediates therefore regains relative strength.

[0046] Clearly, there are certain limits to the practical values ​​for the duration of the gas refresh interval. If the duration is chosen so short that even the "fastest" of the gases involved doesn't have enough time to return to the reaction site in sufficient quantities, the mask processing process will come to a standstill. This lower limit will depend not only on the gases used, but also on their partial pressures in the gas mixture, the temperature at which the processing takes place, and other such factors.

[0047] A typical value of a minimum time duration for the gas refresh interval, which may not be undercut, is, for example, 10 µs or 100 µs.

[0048] In general, typical values ​​for the duration of the gas refresh interval, as they can be used in the context of the present invention, are, for example, in the range from 10 µs to 30 ms, or in the range from 100 µs to 30 ms.

[0049] A typical starting point from which the process rates can be changed relative to each other by changing the duration of the gas refresh interval as described herein, thus "separating" the two partial reactions, would be, for example, a gas refresh interval with a duration of 750 µs.

[0050] To explicitly pick out a specific example, consider the case where the first partial reaction is a passivation process and the first gas is H 2 O, while the second partial reaction is an etching process and the second gas is XeF 2(see also option (i) discussed in more detail below with regard to possible process / gas combinations). In this case, the passivation process can be "selected" or "intensified" by a gas refresh interval with a duration in the range of 50 to 250 µs, and the etching process can be "selected" or "intensified" by a gas refresh interval with a duration in the range of 600 to 1200 µs, whereby further adjustments and optimizations can be made within these ranges if necessary (e.g. in iterative test runs / experiments) in order to maintain or further improve the desired "separation" of the partial reactions.

[0051] As a further specific example, the duration of the gas refreshment interval for the relative increase of the process rate of the first partial reaction compared to the process rate of the second partial reaction can, for example, be selected such that it lies in the following interval I, depending on how strongly the process rate of the first partial reaction is to be emphasized, whereby it is assumed that the first and second accumulation times of the gases involved are known and / or have been determined experimentally, for example in the manner outlined above: I=[first accumulation period; second accumulation period).

[0052] Here, the first attachment time is the (average) attachment time of the first gas at the reaction site, and the second attachment time is that of the second gas.

[0053] The method may further include adjusting one or more exposure parameters, specifically to optimize the first partial reaction.

[0054] In principle, the method can also be used to individually adjust or optimize the exposure parameters for two or more partial reactions. However, for the sake of simplicity, the following discusses the case of a process with only two partial reactions, where optimization is performed with respect to the first.

[0055] As already mentioned, the disclosed method can allow the first partial reaction to be "singled out" over the second partial reaction without additional structural changes or changes to the gas mixture. This, in turn, can allow the exposure parameter(s) to be specifically and decisively tailored to the first partial process, i.e., to be optimized for the first partial reaction. Since the second partial reaction has, to a certain extent, taken a back seat, no, or at least only minor, deteriorations in the second partial reaction need to be accepted, compared to a situation in which optimization with regard to the first partial reaction takes place without prior "singling out" of this partial reaction.

[0056] For example, after sufficient processing of the mask (primarily) by the first partial reaction, the second partial reaction can be brought back to the foreground, e.g., by selecting a different time period for the gas refresh interval (e.g., a longer time period in the range greater than or equal to the second deposition time), and the exposure parameter(s) can then be adjusted again, this time with regard to the second partial reaction. In the example mentioned, according to which the second deposition time is longer than the first, the first partial reaction could be carried out in a first step, with the second partial reaction essentially suppressed (by selecting a shorter time period for the gas refresh interval). However, when carrying out the second partial reaction (by selecting the longer time period for the gas refresh interval) in a second step, the first partial reaction would also proceed to a certain extent. It can, e.g.,By predetermining it before the first step, it can be provided that the total duration of the first step for the first partial reaction is based at least in part on the fact that the first partial reaction also takes place in the second step. Thus, for example, it can be provided that a duration of the first step (e.g., in a predetermined manner) depends at least in part on a duration and / or exposure parameters of the second step (and, of course, vice versa).

[0057] The exposure parameter(s) may, for example, include a duration of the individual exposure intervals for the reaction site.

[0058] For example, the duration of the individual exposure intervals can be constant while the first partial reaction is in the foreground, i.e., while its process rate is increased relative to the process rate of the second partial reaction, but the duration can be different in the case where the second partial reaction has been brought back (more) into the foreground. However, the duration for the individual exposure intervals can also vary from interval to interval while the process rate of the first partial reaction is relatively increased, or between different blocks of intervals, etc.

[0059] As already mentioned, it is also possible that the disclosed method includes the processing of several reaction sites (e.g., several pixels), which are exposed to the beam of energetic particles within one exposure cycle during one or more respective exposure intervals.

[0060] Within such an exposure cycle, the reaction sites can, for example, be passed through one after the other and exposed to the beam of energetic particles during a respective exposure interval in order to trigger and carry out the processing reaction(s) at the respective reaction site. However, it is also possible for certain reaction sites to be processed multiple times rather than once within an exposure cycle (e.g. reaction sites where particularly intensive processing is required), with different numbers of repetitions within an exposure cycle being possible for different reaction sites. For such multiple-exposed reaction sites, the duration of the individual exposure intervals does not have to be constant within a given exposure cycle, but can vary across the cycle.

[0061] The process may involve several such exposure cycles, which can be performed successively.

[0062] The duration of the exposure intervals for the individual reaction sites / pixels is also technically referred to as “dwell time (DWT)” with respect to the corresponding reaction site / pixel.

[0063] The exposure parameter(s) that can be adjusted, especially to optimize the first partial reaction, can in this case also include a duration of the respective exposure intervals for the individual reaction sites.

[0064] The exposure of individual reaction sites (e.g., pixels) or clusters of reaction sites (e.g., clusters of pixels) can therefore be individually controlled and adjusted, although this may also vary from cycle to cycle. This allows the exposure to be precisely adjusted and optimized for the first partial reaction. This may offer significant advantages, for example, when using the process for mask repair, since extremely precise and sensitive work is required to achieve the desired correction effect.

[0065] The exposure parameter(s) that can be adjusted specifically to optimize the first partial reaction may further include a scan pattern with which the reaction sites are exposed sequentially within such an exposure cycle.

[0066] Such a scan pattern allows to define the order in which the individual reaction sites (or clusters of reaction sites) are traversed during processing.

[0067] Tuning the scan pattern specifically to the first partial reaction can, for example, involve the first partial reaction affecting only a smaller area than the second partial reaction—or, for example, in pixel terms, only a subset of all pixels. The scan pattern can then be selected accordingly and expanded to cover the larger area at a later time (e.g., when the processing rate of the second partial reaction has been increased again).

[0068] The scan pattern may also include one or more sub-loops that are run through more than once during an exposure cycle, so that the reaction sites contained in the sub-loops are exposed multiple times in one exposure cycle, as explained above.

[0069] This can be particularly advantageous, for example, when individual reaction sites or clusters of reaction sites require particularly intensive processing during the first partial reaction. Provided that sufficient first gas is always available at the corresponding reaction sites (e.g., if the first gas is "fast enough"), these sites can then be processed multiple times within one exposure cycle, thus saving time.

[0070] A change in such a scan pattern and / or the sub-loop(s) contained therein can also be used "indirectly" to influence the duration of the gas refresh interval with respect to a specific reaction location, and thus the relative process rates of the first and second partial reactions at this location. If, for example, a specific reaction location is addressed multiple times within an exposure cycle, the number of other reaction locations that lie between the exposure intervals for the reaction location in question will influence the gas refresh interval with respect to the reaction location in question, which, according to the disclosure, refers to the time period between two exposure intervals / events at this fixed location. For example, ifIf the sub-loop(s) are shortened, fewer other reaction sites will be processed between two exposure intervals at the reaction site in question, which can shorten the time required for the gas refresh interval with respect to the reaction site in question and thus increase the process rate of the first partial reaction compared to that of the second partial reaction (e.g., if the first gas is a "faster" gas than the second gas). Reducing the number of reaction sites processed in an exposure cycle can also lead to this effect, since here, too, a smaller number of other reaction sites need to be processed between two exposure intervals of a given reaction site.

[0071] All this, of course, does not exclude the possibility that the choice of the duration for the gas refreshment interval can also be made in such a way that actual waiting times are part of the process, during which no exposures take place at all, either at the reaction site under consideration itself or at any other reaction sites that may be present and which are processed as part of the process as just described.

[0072] As a specific example, the scan pattern can contain several sub-loops that are run through one after the other. Each reaction location, e.g. each pixel of the area selected as being to be processed, can be assigned to exactly one sub-loop and exposed exactly once in this sub-loop, with neighboring pixels being assigned to different sub-loops. For example, there can be n sub-loops, with only every nth pixel being exposed in each sub-loop. After running through all the sub-loops, all the pixels have been exposed, i.e. processed, exactly once. The area to be processed and the sequence of sub-loops as well as the assignment of the pixels to these can now be selected such that the selected gas refresh interval elapses between two exposures of a given pixel.If necessary, the duration of the exposure intervals for the individual pixels and / or any waiting times between exposure intervals can also be adjusted. This allows the first partial reaction to be used and carried out particularly effectively and time-efficiently.

[0073] In addition to or as an alternative to the above-mentioned options, as already mentioned, further measures can be taken to increase the process rate of the first partial reaction relative to the second partial reaction, i.e., to "pick out" the first partial reaction even more effectively. One possibility already mentioned would be, for example, to change the respective proportions of the two gases in the gas mixture used.

[0074] Another, additional or alternative, possibility is to heat the reaction site (or sites) using a pulsed laser in order to further influence the process rates of the individual partial reactions.

[0075] This requires a certain temperature dependence of the two partial reactions. For example, if the first partial reaction is favored by higher temperatures, heating can enable even better separation of the first partial reaction from the second partial reaction. Conversely, laser heating can, in a sense, "switch the second partial reaction on" again on demand without having to change the gas refresh interval.

[0076] In other words, in this case, two parameters are available – the duration of the gas refresh interval between two exposure intervals at the reaction site and the degree of heating by the pulsed laser – to adjust the relative strength of the two partial reactions at the reaction site. This, in turn, can enable particularly precise adjustment of the exposure parameters and, more generally, particularly targeted process control and processing sequence.

[0077] If several reaction sites are included in the process, further local fine-tuning of the process rates can be achieved by heating the different reaction sites differently.

[0078] The beam of energetic particles can be a laser beam.

[0079] The use of a laser beam can be advantageous because laser devices in a variety of forms are readily available on the market and can be relatively inexpensive.

[0080] The beam of energetic particles can be an electron beam.

[0081] As a beam of massive particles, an electron beam can achieve a high spatial

[0082] resolution (e.g., a small spatial extent of the reaction site). At the same time, the use of electrons can allow conclusions about the progress of the processing by measuring backscattered electrons and / or secondary electrons during mask processing.

[0083] The beam of energetic particles can also be an ion beam.

[0084] An ion beam may offer even better spatial resolution than an electron beam, but beam guidance may be more complicated and unintentional changes or damage to the mask during processing may also play a greater role.

[0085] The first partial reaction may comprise at least one of the following processes: a passivation process, an etching process, a deposition process, an oxidation process.

[0086] The second partial reaction may comprise at least one of the following processes: a passivation process, an activation process, an etching process, a deposition process.

[0087] The process or the induced (chemical) reaction may also include a third partial reaction which is predominantly mediated by a third gas contained in the gas mixture (a fourth, fifth, etc. partial reaction predominantly mediated by a fourth, fifth, etc. gas is also conceivable).

[0088] Exemplary combinations encompassed by the present invention are the following: (i) The first partial reaction is a passivation process and the second partial reaction is an etching process.

[0089] As the first gas, ie as passivation gas, H 2 O can be used.

[0090] As a second gas, ie as etching gas, XeF 2 If necessary, the second gas may also contain admixtures of MoCO and / or NH 3 in small quantities.

[0091] This combination is useful, for example, when processing HD-PSM materials and HD-PSM masks. (ii) The first partial reaction is an oxidation of the mask surface at the reaction site and the second partial reaction is an etching process.

[0092] The first gas used, ie the oxidizing gas, can be nitrous gases (e.g. N 2 O, NO, NO 2 ), hydrogen oxides (e.g. H 2 O, H 2 O 2 ), molecular or atomic oxygen, and / or ozone are used.

[0093] As a second gas, ie as etching gas, halogen-containing compounds / halides such as halogens (e.g. F 2 , Cl 2 ), hydrogen halides (e.g. HF, HCl), noble gas halides (e.g. XeF 2 ), nitrogen halides (e.g. NF 3 , NOF, NCl 3 , NOCl), halogenated hydrocarbons (e.g. CF 4 , CHF 3 , CC1 4 ), phosphorus halides (e.g. PF 3 , PCl 3 ) s and / or sulfur halides (e.g. SF 6 , SF 4 , SF 2 , SCl 2 , thionyl chloride) are used. (iii) The first partial reaction is an oxidation of the mask surface at the reaction site, and the second partial reaction is an etching process. Furthermore, the method or the induced reaction comprises a third partial reaction, primarily mediated by a third gas contained in the gas mixture, wherein the third partial reaction is a passivation process.

[0094] The first gas used, ie the oxidizing gas, can be nitrous gases (e.g. N 2 O, NO, NO 2 ), hydrogen oxides (e.g. H 2 O, H 2 O 2 ), molecular or atomic oxygen, and / or ozone are used.

[0095] As a second gas, ie as etching gas, halogen-containing compounds / halides such as halogens (e.g. F 2 , Cl 2 ), hydrogen halides (e.g. HF, HCl), noble gas halides (e.g. XeF 2 ), nitrogen halides (e.g. NF 3 , NOF, NCl 3 , NOCl), halogenated hydrocarbons (e.g. CF 4 , CHF 3 , CC1 4 ), phosphorus halides (e.g. PF 3 , PCl 3 ) s and / or sulfur halides (e.g. SF 6 , SF 4 , SF 2 , SCl 2 , thionyl chloride) are used.

[0096] As a third gas, i.e. as a passivation gas, metal carbonyls (e.g. Mo(CO) 6 , Cr(CO) 6 , W(CO) 6 , Fe(CO) 3 ), H 2 O, nitrous gases (e.g. N 2 O, NO, NO 2 ), and / or silicon-containing compounds (e.g. silicates (e.g. TEOS = tetra-ethyl-orthosilicate), silicon isocyanates (e.g. tetraisocyanatosilanes), silanes (e.g. cyclopentasilane), siloxanes and / or silazanes) are used. (iv) The first partial reaction is a deposition process and the second partial reaction is a further reaction to the desired deposition product.

[0097] Here, the first gas, i.e. the deposition gas, can be, for example, silicon-containing compounds (e.g. silicates (e.g. TEOS = tetra-ethyl-orthosilicate), silicon isocyanates (e.g. tetraisocyanatosilanes), silanes (e.g. cyclopentasilane), siloxanes and / or silazanes)) and / or metal carbonyls (e.g. Mo(CO) 6 , Cr(CO) 6, W(CO) 6 , Fe(CO) 5 ) are used.

[0098] As a second gas, ie as a reactant, NH 3 as nitrating agent and / or e.g. H 2 O or NO 2 used as oxidizing agents. Nitrous gases (e.g. N 2 O, NO, NO 2 ), hydrogen oxides (e.g. H 2 O, H 2 O 2 ), molecular or atomic oxygen, and / or ozone are also conceivable as a second gas. (v) The first partial reaction is a deposition process and the second partial reaction is a purification process.

[0099] Here, organometallic compounds (e.g. Pt, Pd, Ru, Re, Rh, Ir, and / or Au-containing precious metal or Cu, Ni, Co, Fe, Mn, Cr, Mo, W, V, Nb, Ta, Zr, Hf compounds) can be used as the first gas, i.e. as the deposition gas.

[0100] As a second gas, ie as a cleaning gas, H 2 O or NO2 for oxidation. Nitrous gases (e.g. N 2 O, NO, NO 2 ), hydrogen oxides (e.g. H 2 O, H 2 O 2 ), molecular or atomic oxygen, and / or ozone. Alternatively or additionally, NOCl or XeF 2 for halogenation. Also conceivable are halogen-containing compounds / halides such as halogens (e.g. F 2 , Cl 2 ), hydrogen halides (e.g. HF, HCl), noble gas halides (e.g. XeF 2 ), nitrogen halides (e.g. NF 3 , NOF, NCl 3 , NOCl), halogenated hydrocarbons (e.g. CF 4 , CHF 3 , CC1 4 ), phosphorus halides (e.g. PF 3 , PCl 3 ) s and / or sulfur halides (e.g. SF 6 , SF 4 , SF 2 , SCl 2 , thionyl chloride).

[0101] In a third partial reaction, the non-vacuum-resistant oxygen or halogen compounds can then decompose and leave behind pure metal compounds.

[0102] At this point, it is emphasized that the combination of partial reactions mentioned as option (v) (i.e., the first partial reaction is a deposition process and the second partial reaction is a purification process, using the gases mentioned and optionally including a third partial reaction in which the non-vacuum-resistant oxygen or halogen compounds decompose and leave behind pure metal compounds) represents an independent invention, which can also be claimed without selection and manipulation of the relative process rates and the gas refreshment interval as described herein. Thus, for example, the present disclosure encompasses as an independent invention a modified process which includes the steps (a.), (b.), (b1.) and (b2.) already described, but not necessarily also steps (c.) and / or (d.), and in which the partial reactions mentioned as option (v) take place.All other optional process steps and modifications described herein can also be combined with this modified process, even if this is not explicitly listed or discussed here for the sake of brevity. Analogous statements also apply to a device and software for implementing such a modified process (see the corresponding explanations below).

[0103] In particular, the disclosed method for correcting a defect of the mask (or a wafer / chip surface, etc., cf. the introductory statements) can be used. Since a high accuracy of the individual processing steps is necessary for this - especially with modern masks and in view of the ever-increasing integration density - the possibility of selectively controlling and accessing individual partial reactions offers new possibilities for optimizing the individual partial reactions, e.g. with regard to the exposure parameters used.

[0104] At this point, it should be noted that although the possible features, options, and modifications of the disclosed method have been described in a specific order up to this point, this is not necessarily intended to express a particular interdependence of the features - unless explicitly stated otherwise. Rather, the various features and options can also be combined in other orders and permutations - as far as physically and technically possible - and such combinations of features or even sub-features are also encompassed by the present invention. Individual features or sub-features can also be omitted if they are unnecessary to achieve the desired technical result.

[0105] A device for processing an object, in particular a lithographic mask, comprises in one embodiment (a.) means for supplying a gas mixture comprising at least a first gas and a second gas to a reaction site on a surface of the object; (b.) means for inducing a (chemical) reaction, which comprises at least a first partial reaction and a second partial reaction, at the reaction site by exposing the reaction site to a beam of energetic particles at exposure intervals, wherein the first partial reaction is predominantly mediated by the first gas and the second partial reaction is predominantly mediated by the second gas, and wherein a gas refresh interval lies between the respective exposure intervals; (c.) means for selecting the first partial reaction in order to increase its process rate relative to a process rate of the second partial reaction; and (d.) Means for selecting a time duration for the gas refresh interval which causes the relative increase in the process rate of the first partial reaction compared to the process rate of the second partial reaction.

[0106] Generally speaking, an advantage of the disclosed method is that it allows for the targeted influencing of individual partial reactions without requiring a fundamentally new design of the devices used for carrying out the process. Thus, if the device described here is intended for mask repair, for example, it can be based on one of the mask repair devices developed and marketed by the applicant.

[0107] However, to the applicant's current knowledge, the deliberate selection of individual partial reactions was not provided for in previous apparatuses. In contrast, the device described here allows the targeted highlighting of one of the involved partial processes through a suitable and targeted selection of the duration of the gas refreshment interval, as described in detail above in the discussion of the disclosed method.

[0108] In particular, the device may automatically select the time duration for the gas refresh interval based on the selection of the first partial reaction for the relative amplification of its process rate.

[0109] For example, the first gas can have a first attachment time at the reaction site and the second gas a second attachment time, and the means for selecting the time period for the gas refresh interval selects the time interval based on the first and second attachment times such that the relative increase in the process rate of the first partial reaction compared to the process rate of the second partial reaction is effected, as described above. As mentioned, this can take place automatically. The relevant values ​​and data, e.g. the first and second attachment times for the first and second gases used, can be available to the device as stored values ​​and / or obtained from a database. Or the device contains suitable means for determining these values ​​experimentally, either during operation (i.e. during the processing of the mask itself) or in a dedicated test mode.

[0110] Finally, a computer program may comprise instructions which, when executed, cause a device, for example as described herein, to perform the steps of one of the embodiments of the disclosed method. 4. Short description of the characters

[0111] In the following detailed description, possible embodiments of the invention are described with reference to the figures, wherein the Fig. 1a-c schematically show a mask at different times during processing using an embodiment of the disclosed method; and Fig. Figure 2 shows a schematic diagram of an embodiment of an apparatus as may be used to carry out the disclosed method. 5. Detailed description of possible embodiments

[0112] In the following, embodiments of the present invention are described primarily with reference to the repair of a lithographic mask. However, the invention is not limited thereto and can also be used for other types of mask processing, or more generally for the surface processing of other objects used in the field of microelectronics, e.g., for modifying and / or repairing structured wafer surfaces or microchip surfaces, etc. Even though reference is therefore primarily made below to the application of processing a mask surface in order to keep the description clear and easier to understand, the other possible applications of the disclosed teaching will nevertheless remain apparent to those skilled in the art.

[0113] It is further noted that only individual embodiments of the invention can be described in more detail below. However, those skilled in the art will understand that the features and possible modifications described in connection with these embodiments can also be further modified and / or combined with one another in other combinations or sub-combinations without this departing from the scope of the present invention. Individual features or sub-features can also be omitted if they are unnecessary to achieve the intended result. To avoid unnecessary repetition, reference is made to the statements and explanations in the preceding sections, which also remain valid for the detailed description that follows.

[0114] The Fig. 1a-c schematically illustrate how the duration of the gas refresh interval is used to increase the process rate of a first partial reaction relative to a second partial reaction in one embodiment of the invention.

[0115] The method shown is used to process a lithographic mask 100 (or another microelectronic object, e.g., a wafer or microchip). To process the mask 100, a gas mixture is supplied to a reaction site 110 on a surface 120 of the mask 100. As already mentioned, the reaction site 110 can be located substantially on the surface 120 of the mask 100 or can extend a certain depth (e.g., several atomic layers deep) into the mask 100. In addition, the surface 120, and thus also the reaction site 110, will generally change slightly during processing, e.g., during an etching or deposition process during mask repair.

[0116] The processing is carried out in such a way that the reaction site 110 is exposed in several exposure intervals to a beam of energetic particles which is directed into the Fig. 1a-c by the arrow 115 and the dotted lines to its right and left. Beam 115 can be, for example, a laser beam, an electron beam, or an ion beam.

[0117] In the Fig. 1a-c, the mask 100 is schematically divided into a part 130 (labeled "exposed area"), which is exposed to the light exposure and comprises the reaction site 110 on the mask surface to be processed, as well as adjacent areas 140 (labeled "unexposed area"), which are not exposed to the light exposure and on which, therefore, no processing will take place in the embodiment discussed here. The areas 140 can also be processed in further processing steps (e.g., by successively passing through several reaction sites along a scan pattern over one or more cycles; for the sake of simplicity, this is shown in the Fig. 1a-c but not shown).

[0118] As already explained at the beginning, the term "reaction site" in the context of the present disclosure can be understood as a pixel or, more generally, as a spatial unit at which the processing can be carried out in a locally limited manner by illuminating and inducing the respective partial reaction(s). The spatial extent of the reaction site can therefore depend, for example, on the type of particle beam 115 used, its focusing, the type of reaction, etc. It should be noted that the images of the Fig. 1a-c are only schematic representations which do not necessarily have to reflect the actual conditions to scale.

[0119] The gas mixture supplied to the reaction site 110 contains, in the embodiment shown here, two gases, namely a first gas 150, which is Fig. 1a-c is designated as “Gas 1” and whose gas atoms or molecules are schematically represented by the symbol “°” (open circle), and a second gas 160, which is in the Fig. 1a-c is designated "Gas 2" and whose gas atoms or molecules are schematically represented by the symbol "▼" (downward-pointing, gray-filled triangle). Each of the two gases 150 and 160 predominantly mediates its own partial reaction involved in the mask processing, i.e., the mask processing includes a (chemical) reaction with a first partial reaction, which is primarily mediated by the gas 150, and a second partial reaction, which is primarily mediated by the gas 160. As already described above, "predominantly" can mean that without the corresponding gas, the partial reaction will not take place, at least not to a noticeable extent, whereas if the gas is present at the reaction site with a certain minimum concentration, the partial reaction can take place. The (chemical) reaction with the partial reactions contained therein is induced by exposure to the beam 115 of energetic particles, i.e.triggered or set in motion.

[0120] It should be mentioned at this point that in other embodiments, the gas mixture supplied to the reaction site 110 may also contain further gases, for example a third gas which predominantly mediates a third partial reaction, etc. For the sake of simplicity, however, only the two gases 150 and 160 and the corresponding two partial reactions will be discussed below.

[0121] The gas 150 and / or the gas 160 can also themselves represent a gas mixture.

[0122] The Fig. Figure 1a schematically shows the state after an exposure interval, i.e., after the reaction site 110 has been exposed to the beam 115 of energetic particles. As can be seen, the first and second partial reactions were triggered by the exposure, and by the completion of both partial reactions, both the gas 150 (cf. "°") and the gas 160 (cf. "▼") were essentially consumed, and the gases are therefore depleted or no longer present at the reaction site 110.

[0123] In order to repeat the processing reaction with its partial reactions (mask processing typically involves a number of processing passes, since, for example, an etching or deposition process cannot be performed with the desired accuracy in a single pass), gas must be supplied again. This is achieved by a gas refresh interval, which lies between the individual exposure intervals. During this gas refresh interval, the gases 150 and 160 contained in the gas mixture used diffuse to the reaction site 110 and adsorb there on and / or near the surface 120 of the mask 100 (the gas atoms / molecules may also penetrate a certain depth into the mask 100).

[0124] According to the invention, one of the two partial reactions is deliberately and selectively selected in order to increase its process rate relative to the process rate of the other partial reaction. For the sake of clarity, the partial reaction selected and chosen to increase its process rate is always referred to here as the first partial reaction.

[0125] In order to achieve the relative increase in the process rate of the first partial reaction compared to the second partial reaction, the duration of the gas refreshment interval is appropriately selected or adjusted. Fig. Figure 1b shows schematically the state after the selected gas refresh interval has expired.

[0126] The two gases 150 and 160 shown here differ in their physical and chemical properties. Firstly, as already mentioned, the two gases 150 and 160 mediate different partial reactions. Secondly, they also have different diffusion and adsorption properties with respect to the mask surface 120 at the reaction site 110. This results in the two gases 150 and 160 having different adsorption times, i.e., the time required for them to be sufficiently "refreshed" at the reaction site 110 is different (these are generally average values, as is usual with such thermodynamic processes).

[0127] In the present case, the gas 150 is a "fast" gas, while the gas 160 is a "slower" gas, ie the gas 150 has a shorter attachment time to the mask surface 120 at the reaction site 110 than the gas 160. Consequently, during the selected gas refresh interval, which here was chosen, for example, to be shorter than the second attachment time, or in particular in the following interval I=[first accumulation period; second accumulation period). the first gas 150 has already had sufficient time to accumulate at the reaction site 110 on the mask surface 120 to such an extent that the first partial reaction can be triggered and carried out again by exposure to the particle beam 115. However, the second gas 160 has not yet accumulated a sufficient amount or at least only a small amount at the reaction site 110, so that the second partial reaction can be carried out in comparison to the situation in Fig. 1a can only occur to a noticeably lesser extent (if at all).

[0128] In the Fig. In the case outlined in Figure 1b, the concentration of the gas 150 diffused to the reaction site 110 and adsorbed there is greater than the concentration of the gas 160 after the end of the gas refreshment interval.

[0129] By selecting the duration of the gas refresh interval, the process rate of the second partial reaction is suppressed relative to the process rate of the first partial reaction, without, for example, having to change anything in the introduced gas mixture (although this would also be conceivable as an alternative or in addition to the approach described here in order to enhance one of the two partial reactions relative to the other). Viewed the other way around, the desired relative increase in the process rate of the first partial reaction relative to the second partial reaction is achieved by the selected duration of the gas refresh interval.

[0130] At this point it should be noted that it is fundamentally conceivable that in the Fig. 1b, the absolute process rate of the second partial reaction is still greater than the absolute process rate of the first partial reaction. This will generally depend on other factors, such as the nature of the two partial reactions, the mask material, etc. In any case, however, a relative shift of the two process rates in favor of the first partial reaction takes place. One conceivable numerical measure to quantify this is, for example, the quotient of the absolute process rates of the first partial reaction to the second partial reaction, which increases in the case shown. However, it is also expressly possible that the process rate of the first partial reaction becomes absolutely greater than the process rate of the second partial reaction.

[0131] Based on the Fig. In the situation outlined in Figure 1b (or a similar situation), shortening the duration of the gas refreshment interval can lead to a further relative increase in the process rate of the first partial reaction compared to the process rate of the second partial reaction, even if this may simultaneously be associated with a decrease in the absolute process rate of the first partial reaction. In this case, the duration of the gas refreshment interval can also be selected to be shorter than the first accumulation period, for example, ≥ 50% of the first accumulation period or ≥ 75% of the first accumulation period. However, there is a certain lower limit to any further shortening of the duration of the gas refreshment interval (e.g., 50% of the first accumulation period), since below this period, even the first gas 150 is no longer “fast” enough, and both partial reactions then effectively come to a standstill.

[0132] On the other hand, an extension of the gas refresh interval time from the Fig. 1b (or a similar situation), the equilibrium will shift back in favor of the second partial reaction, ie, it will lead to a relative reduction of the process rate of the first partial reaction compared to the process rate of the second partial reaction, ie, it will lead to a relative increase of the process rate of the second partial reaction compared to the process rate of the first partial reaction. An example of this case is shown in Fig. 1c shows the situation when a long time period is selected for the gas refresh interval (compared to the time period that leads to the situation in Fig. 1b), in which both the first gas 150 and the second gas 160 have again accumulated to a noticeable extent at the reaction site 110. Compared to the state in Fig. 1b, the process rate of the second partial reaction will be significantly increased. Although the process rate of the first partial reaction is also higher compared to Fig. 1b may be slightly increased, has been found in Fig. 1c, the ratio of the process rates is shifted back toward the second partial reaction. In the limiting case, with a sufficiently long gas refreshment interval, a saturation state can occur in which both gases 150 and 160 are adsorbed in saturated concentrations at reaction site 110, so that a further extension of the gas refreshment interval will no longer lead to any noticeable change in the (relative) process rates.

[0133] Alternatively or in addition to the mechanisms described here, it is also possible to heat the reaction site 110 or the mask 100 and / or mask surface 120 in this area, e.g., using a pulsed laser, in a targeted and controlled manner, in order to influence the process rates of the first and second partial reactions absolutely and / or relative to one another. For example, the process rates of the partial reactions themselves can depend on the temperature, or they can be influenced indirectly by the heating via a temperature dependence of the diffusion and adsorption properties of the gases 150 and 160, or by a combination of direct and indirect influences.

[0134] After the process rate of the first partial reaction has been determined, for example, as in Fig. 1b, relative to the process rate of the second partial reaction, one or more exposure parameters used to expose the reaction site 110 with the particle beam 115 can be adjusted and set to specifically optimize the first partial reaction. As already explained in detail above, this can include various parameters (combinations) and approaches. For example, the exposure times of the multiple exposure intervals can be adjusted.

[0135] Furthermore, the method may comprise the processing of several reaction sites (in the Fig. 1a-c not shown), which are exposed to the beam 115 of energetic particles during one or more respective exposure intervals within an exposure cycle. Preferably, the method comprises a plurality of such exposure cycles. In this case, the one or more exposure parameters used during the exposure with the particle beam 115 can include a duration of the respective exposure intervals for the individual reaction sites. The one or more exposure parameters can also include a scan pattern with which the reaction sites are exposed sequentially. Such a scan pattern can also include one or more sub-loops. These can be run through exactly once during an exposure cycle.However, one or more of the subloops can also be run through more than once during an exposure cycle, so that the reaction sites contained in these subloops are exposed multiple times in one exposure cycle. Details of this have already been discussed in Section 3, to which reference is made.

[0136] The first partial reaction may, for example, comprise a passivation process, an etching process, a deposition process, or an oxidation process. The second partial reaction may, for example, comprise a passivation process, an activation process, an etching process, or a deposition process. Furthermore, the processing of the mask 100 may comprise a third partial reaction that is predominantly mediated by a third gas, etc.

[0137] Specific possibilities and partial reaction combinations as well as suitable gases have already been described above as combination possibilities “(i)”, “(ii)”, “(iii)”, “(iv)” and “(v)”, and for the sake of brevity, reference is therefore made to the above explanations.

[0138] Furthermore, reference is again made to the independent inventive content of option (v) as such, as already explained above.

[0139] Finally, it is again pointed out that the method can be used in particular to correct a defect in the mask 100, i.e. to repair the mask.

[0140] The Fig. 2 schematically shows an embodiment 200 of an apparatus as can be used to carry out the disclosed method for processing a mask 100. For the sake of consistency, the same reference numerals are used with respect to the mask 100 and the gases 150 and 160, etc. as in the Fig. 1a-c. The above statements therefore continue to apply. However, this does not mean that the device 200 is only suitable for carrying out the Fig. 1a-c discussed specific embodiments of the disclosed method.

[0141] Furthermore, devices for mask processing and mask repair are generally known to those skilled in the art. For example, the applicant itself develops and markets devices for mask repair. Device 200 could, for example, be based on one of these devices, and therefore not all details of device 200 will be discussed in detail below.

[0142] The device 200 comprises means 210 for supplying a gas mixture containing at least a first gas 150 ("Gas 1") and a second gas 160 ("Gas 2") to a reaction site 110 on a surface 120 of the mask 100, as well as means 220 for inducing a (chemical) reaction, which includes at least a first partial reaction and a second partial reaction, at the reaction site 110 by exposing the reaction site 110 to a beam of energetic particles in multiple exposure intervals. As already described several times, the first partial reaction is predominantly mediated by the first gas 150 and the second partial reaction is predominantly mediated by the second gas 160. A gas refresh interval lies between the respective exposure intervals.

[0143] The particle beam may, for example, be a laser, electron or ion beam, and the means 220 may be designed accordingly.

[0144] As a further component, the device comprises means 230 for selecting the first partial reaction in order to increase its process rate relative to a process rate of the second partial reaction. The means 230 can be controllable and accessible, for example, via a user interface (hardware or software), thus enabling the user to specifically select a partial reaction in order to then be able to adapt and optimize the exposure parameters and / or other process parameters specifically and purposefully for this partial reaction.

[0145] Furthermore, the device 200 comprises means 240 for selecting a time duration for the gas refresh interval, which brings about the relative increase in the process rate of the first partial reaction compared to the process rate of the second partial reaction. In particular, after the first partial reaction has been selected by the means 230, which may have a connection 235 to the means 240, the means 240 can automatically select a suitable time duration for the gas refresh interval in order to bring about the relative increase in the process rate of the first partial reaction. Several variants are conceivable for this purpose.

[0146] For example, if the first gas 150 has a first accumulation time at the reaction site 110 and the second gas 160 has a second accumulation time, the means 240 can select the time duration for the gas refreshment interval based on the first and second accumulation times such that the relative increase in the process rate of the first partial reaction compared to the process rate of the second partial reaction is effected. For example, the time duration can be selected to be shorter than the second accumulation time or from the interval I=[first accumulation period; second accumulation period).

[0147] The relevant values ​​and data, e.g. the first and second storage times for the first and second gases 150 and 160 (and possibly other gases), can be available to the device 200 as stored values ​​and / or can be obtained from a database.

[0148] Additionally or alternatively, the device may include suitable means 242 for experimentally determining these and / or other values ​​relevant for the appropriate selection of the time duration, either during operation (i.e., during the processing of the mask 100 itself) or in a dedicated test mode. The means 242 may, for example, comprise a sensor which, in a test mode, records the concentration of the first and second gases 150 and 160 at the reaction site 110 as a function of the elapsed duration of the gas refresh. The means 242 may be connected to or interact with the means 240 in order to enable the means 240 to evaluate such a series of measurements and thus to appropriately select the duration of the gas refresh interval.

[0149] Additionally or alternatively, a manual selection of the time duration for the gas refresh interval may also be possible via the means 240, e.g. via a user interface (hardware-side or software-side).

[0150] The means 240 may have a connection 215 to the means 210, which serve for gas supply, so that the gas supply can take place according to the gas refresh interval selected by the means 240. The means 240 may also have a connection 225 to the means 220, which serve to induce the processing reaction with its partial reactions by exposure, so that the exposure can be suspended during the gas refresh interval.

[0151] Alternatively or in addition to these components, the device can further comprise means 250 for the targeted heating of the reaction site 110 or the mask 100 and / or mask surface 120 in this area. In particular, the means 250 can comprise a pulsed laser. As already described above, the targeted heating can directly and / or indirectly influence the process rates of the first and second partial reactions. The means 250 can be connected to the means 240 via a connection 255, so that the means 240 for selecting the duration of the gas refresh interval and the means 250 for heating can cooperate to effect the desired influence on the process rates of the first and second partial reactions.

[0152] Additionally or alternatively, the means 250 can also be directly connected or interact with the means 210 and 220 (in the Fig.2 not shown) to influence the process rates independently of the means 240.

[0153] Finally, a computer program with instructions causing the device to carry out an embodiment of the disclosed method can be executed, for example in a computing or control unit of a mask processing device.

Claims

[1] A method for processing a surface (120) of an object, comprising: a. supplying a gas mixture comprising at least a first gas (150) and a second gas (160) to a reaction site (110) on the surface (120) of the object; b. Inducing a reaction, which includes at least a first partial reaction and a second partial reaction, at the reaction site (110) by exposing the reaction site (110) to a beam of energetic particles (115) in a plurality of exposure intervals, wherein b1. the first partial reaction is predominantly mediated by the first gas (150) and the second partial reaction is predominantly mediated by the second gas (160), and wherein b2. there is a gas refresh interval between the respective exposure intervals; c. Setting a first time period for the gas refresh interval, whereby a process rate of the first partial reaction and a process rate of the second partial reaction are present; d. Setting a second time period for the gas refresh interval which causes a relative increase in the process rate of the first partial reaction compared to the process rate of the second partial reaction. [2] The method of claim 1, wherein the first gas (150) has a first attachment time to the reaction site (110) and the second gas (160) has a second attachment time that is greater than the first attachment time, and wherein the second time period for the gas refresh interval is set to be less than the second attachment time. [3] Method according to claim 1 or 2, wherein the second time period for the gas refresh interval is set such that a concentration of the first gas (150) diffused to the reaction site (110) and adsorbed there on the surface (120) during the gas refresh interval is higher than a concentration of the second gas (160). [4] Method according to one of claims 1-3, wherein, starting from the second set time period, a shortening of the gas refresh interval leads to a further relative increase in the process rate of the first partial reaction compared to the process rate of the second partial reaction, while an extension of the gas refresh interval leads to a relative reduction in the process rate of the first partial reaction compared to the process rate of the second partial reaction. [5] The method of any one of claims 1-4, further comprising adjusting one or more exposure parameters used to expose the reaction site (110) to the beam, specifically to optimize the first partial reaction. [6] The method of claim 5, wherein the one or more exposure parameters comprise a duration of the individual exposure intervals for the reaction site (110). [7] The method of any one of claims 1-6, wherein the method comprises processing a plurality of reaction sites (110) exposed to the beam of energetic particles (115) during one or more respective exposure intervals within an exposure cycle. [8] The method of claim 7 in combination with claim 5, wherein the one or more exposure parameters comprise a duration of the respective exposure intervals for the individual reaction sites (110). [9] Method according to claim 7 in combination with claim 5 or according to claim 8, wherein the one or more exposure parameters include a scan pattern with which the individual reaction sites (110) are exposed in sequence. [10] The method of claim 9, wherein the scan pattern includes one or more sub-loops that are traversed more than once during an exposure cycle, so that the reaction sites (110) included in the one or more sub-loops are exposed multiple times in one exposure cycle. [11] Method according to one of claims 1-10, further comprising heating the reaction site (110) by a pulsed laser in order to further influence the process rates of the individual partial reactions. [12] The method of any of claims 1-11, wherein the beam of energetic particles (115) is a laser beam. [13] The method of any of claims 1-11, wherein the beam of energetic particles (115) is an electron beam. [14] The method of any of claims 1-11, wherein the beam of energetic particles (115) is an ion beam. [15] The method according to any one of claims 1-14, wherein the first partial reaction comprises at least one of the following processes: a passivation process, an etching process, a deposition process, an oxidation process. [16] The method according to any one of claims 1-15, wherein the second partial reaction comprises at least one of the following processes: a passivation process, an activation process, an etching process, a deposition process. [17] A process according to any one of claims 1-16, wherein the reaction further includes a third partial reaction mediated predominantly by a third gas contained in the gas mixture. [18] The method of any of claims 1-17, wherein the object comprises a lithographic mask (100). [19] The method of claim 18, wherein the method is for correcting a defect of the mask (100). [20] A computer program with instructions which, when executed, cause a device (200) for processing a surface (120) of an object, in particular a surface (120) of a lithographic mask (100), to carry out the method according to any one of claims 1-19; wherein the device (200) for processing a surface (120) of an object comprises: a. means (210) for supplying a gas mixture comprising at least a first gas (150) and a second gas (160) to a reaction site (110) on the surface (120) of the object; b. means (220) for inducing a reaction, which includes at least a first partial reaction and a second partial reaction, at the reaction site (110) by exposing the reaction site (110) to a beam of energetic particles (115) in a plurality of exposure intervals, wherein b1. the first partial reaction is predominantly mediated by the first gas (150) and the second partial reaction is predominantly mediated by the second gas (160), and wherein b2. there is a gas refresh interval between the respective exposure intervals; c. means (240) for automatically setting a first time period for the gas refresh interval, whereby a process rate of the first partial reaction and a process rate of the second partial reaction are present; d. Means (240) for automatically setting a second time period for the gas refresh interval which causes a relative increase in the process rate of the first partial reaction compared to a process rate of the second partial reaction.

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