DEVICE AND METHOD FOR REMOVAL OF PROCESS GAS FROM VACUUM PROCESSING SYSTEMS AND CORRESPONDING VACUUM PROCESSING SYSTEM

Abstract

The present invention relates to a device for removing process gases from vacuum processing systems, in particular electron beam systems for defect identification during and / or repair of lithography masks, comprising a cooling device (3) with at least one cooling surface (4) for adsorption or condensation of process gases, wherein the device includes thermal insulation (2) of the cooling surface (4) of the cooling device (3) from the environment, which is activatable and deactivatable. The invention further comprises a vacuum processing system with such a device (1) and a method for operating a vacuum processing system.

Description

BACKGROUND OF THE INVENTION AREA OF THE INVENTION

[0001] The present invention relates to a device for removing process gases from vacuum processing systems, in particular electron beam systems for fault identification during and / or repair of lithography masks, with a cooling device for adsorption or condensation of process gases, as well as a vacuum processing system and a method for operating a vacuum processing system with a corresponding device. STATE OF THE ART

[0002] The repair of various types of mask defects in lithography masks for UV (ultraviolet), DUV (deep ultraviolet), and especially EUV (extreme ultraviolet) projection exposure systems utilizes particle beam-based processes with process gas support, particularly electron beam-based processes, also known as focused electron-beam induced processing (FEBIP). Different process gases and mask types are employed for each method. In semiconductor fabrication, it is essential that the changeover between repair processes occurs with minimal downtime between repairs.

[0003] It can happen that process gases remaining in the process chamber, which were used for a first repair process, have a disruptive effect on a second repair process. This disruptive effect can take the following forms: 1) A process gas of the first repair process is only used in the first repair process and interacts in an undesirable way with the subsequent repair process. 2) A repair process and a subsequent repair process require the provision of the same process gas under different conditions, for example, at different gas flows.

[0004] For example, a first repair process for photomasks may use at least one precursor gas, which slows down etching processes. Any precursor remaining in the process chamber after the repair can then lead to an undesirable slowdown of a subsequent second repair process.

[0005] Drift correction markers are often produced using precursors suitable for electron beam-induced deposition. Precursor gas remaining in the chamber can affect subsequent processes, e.g., slowing down the etching process.

[0006] Furthermore, in the future, an increasing number of photomask types with different process conditions will need to be repaired alternately in a single mask repair device. The requirement for this is that the individual repair processes should interfere with each other as little as possible.

[0007] According to the current state of the art, switching between different repair processes requires a waiting period during which the process gas remaining in the chamber is pumped out by the pumping system. This waiting period reduces the throughput. REVELATION OF THE INVENTIONAL TASK OF INVENTION

[0008] It is therefore an object of the present invention to provide a device for removing unwanted process gases from vacuum processing systems, in particular electron beam systems for fault identification during and / or repair of lithography masks, as well as corresponding vacuum processing systems and methods for operating them, which enable rapid changes of workpieces to be processed and / or processing parameters and in particular of process gases, while maintaining high processing quality. Furthermore, the device should be simple in design and reliably operable. TECHNICAL SOLUTION

[0009] The problem described above is solved by a device for removing process gases from vacuum processing systems with the features of claim 1, as well as a vacuum processing system with the features of claim 7 and a method for operating a vacuum processing system with the features of claim 9. Advantageous embodiments are the subject of the dependent claims.

[0010] To solve the problems described, vacuum processing systems, such as mask repair systems, are equipped with switchable cooling traps. The cooling trap is a cooling device that provides a cooled surface in the process chamber, which is thermally isolated from the workpiece being processed, for example, the mask to be repaired.

[0011] The temperature of the cooled surface is low enough to at least reduce the concentration of process gases remaining in the vacuum chamber through condensation, which could interfere with the subsequent repair.

[0012] During the repair, the cold trap is isolated from the process chamber, preventing adsorption or condensation of process gas molecules on the cooled surface during this period. The repair process is therefore unaffected. The cold trap is only activated after the repair is complete, i.e., after the supply of process gases has ceased.

[0013] While cold traps for particle beam systems that use process gases are already known in the prior art (US 9 799 490 B2, DE 10 2020 105 706 B4), these cold traps are used continuously during the processing operation.

[0014] The invention thus provides a device for removing process gases from vacuum processing systems, in particular electron beam systems for fault identification during and / or repair of lithography masks, with a cooling device for adsorption or condensation of process gases, wherein the device comprises thermal insulation of the cooling device from the environment, which can be activated and deactivated.

[0015] The activatable and deactivatable thermal insulation can be a movable enclosure or closure relative to the cooling device, wherein the enclosure or closure is movable, in particular displaceable, between a first position in which the space around the cooling device is closed and the thermal insulation is activated, and a second position in which the space around the cooling device is open and the thermal insulation is deactivated. Alternatively or additionally, the cooling device itself can also be designed to be movable.

[0016] The device may include a drive, in particular a mechanical drive, for moving the casing or closure and / or the cooling device.

[0017] The device may include an evacuation and / or purging device for evacuating a space surrounded by thermal insulation and / or for purging the space surrounded by thermal insulation with a gas and / or a fluid.

[0018] The cooling device can provide at least one cooling surface that can be cooled by heat conduction in conjunction with a cold reservoir, by contact with a cooling medium, or by thermoelectric cooling with one or more Peltier elements.

[0019] The at least one cooling surface of the cooling device can also be designed to be heated.

[0020] A vacuum processing system according to the invention, in particular an electron beam system for fault identification during and / or repair of lithography masks, is equipped with a vacuum chamber for receiving a workpiece to be processed and a gas supply device with which at least one process gas can be provided in the vacuum chamber before and / or during processing of a workpiece, as well as with at least one device of the type described above for activating and deactivating an insulation.

[0021] The vacuum processing system can be a mask repair system for repairing lithography masks, especially masks for UV, DUV and EUV lithography or embossing dies for nanoimprint lithography.

[0022] In the inventive method for operating a vacuum processing system, and in particular a vacuum processing system of the type described above, after completion of processing a workpiece in a vacuum chamber of the vacuum processing system, the supply of process gas to the vacuum chamber is stopped and a cooling device with an activatable and deactivatable thermal insulation is activated by deactivating the thermal insulation for adsorption or condensation of process gas, in order to subsequently reactivate the thermal insulation and carry out further processing of another workpiece or of the already processed workpiece with different process parameters.

[0023] During the deactivation of the thermal insulation, the workpiece being processed can be changed.

[0024] After the adsorption or condensation of process gas on at least one cooling surface of the cooling device, the cooling device can be heated and / or a space surrounded by the thermal insulation can be purged and / or evacuated during the activation of the thermal insulation. BRIEF DESCRIPTION OF THE FIGURES

[0025] The attached drawings show in a purely schematic way in Fig. 1 an embodiment of a device according to the invention with a cooling device (cold trap) with spatial thermal insulation from the environment (activated thermal insulation), Fig. 2 the device from Fig. 1 with thermal insulation deactivated, Fig. 3 an embodiment of a system 100 for analyzing and / or processing a workpiece and in Fig. 4 a further embodiment of a cooling device according to the invention that can be activated and deactivated EXAMPLES OF EXECUTION

[0026] Further advantages, characteristics, and features of the present invention will become apparent in the following detailed description of the exemplary embodiments. However, the invention is not limited to these exemplary embodiments.

[0027] The Fig. Figure 1 schematically shows a cooling surface 4, which is separated from the environment, e.g. a vacuum or process chamber 102, by means of an enclosure 2 (see Fig. 3), in which the device is made of Fig. 1 can be arranged in a spatially isolated enclosure. The pressure in the insulating enclosure 2 can be adjusted by a pump device P independently of the environment, e.g., the chamber vacuum of a surrounding vacuum or process chamber 102. Simultaneously, a purge device can be provided to vent and / or purge the enclosure 2 with a gas. The surface 4 to be cooled can also be heated to desorb condensed process gas.

[0028] Is the cooling surface 4, which can be cooled, for example, by a cooling medium C such as liquid nitrogen, released by deactivating the insulation 2, i.e., as in Fig. As shown in Figure 2, when the cooling surface 4 is opened, it comes into contact with the process gases 7 remaining in the surrounding vacuum or process chamber 102, which condense on the cooling surface 4. Accordingly, after completion of a machining or repair process and cessation of the supply of process gas to the surrounding vacuum or process chamber 102 (see Figure 2), the cooling surface 4 can be opened. Fig. 3) the thermally insulating enclosure 2 is opened (= switching on the cold trap), so that gas molecules from the surrounding vacuum or process chamber 102 can adsorb onto the cooling surface 4.

[0029] Fig. Figure 3 shows a schematic view of an embodiment of a system 100 for analyzing and / or processing a workpiece (sample) 10. The system 100 has a vacuum housing 102, the interior of which is kept at a specific vacuum by a vacuum pump 104.

[0030] The system 100 is specifically designed for analyzing and processing samples 10, particularly in the form of lithography masks. For example, the system serves as a verification and / or repair tool for lithography masks, especially for lithography masks used in EUV, DUV, or UV lithography. A sample 10 to be analyzed or processed is placed on a sample stage 11 within the vacuum housing 102. The sample stage 11 of the system 100 is specifically designed to adjust the position of the sample 10 to within a few nanometers in three spatial directions and three rotational axes.

[0031] The system 100 further comprises a delivery unit 106 in the form of an electron column. This includes an electron source 108 for providing an electron beam 110 (particle beam) and an electron microscope 112, which detects the electrons backscattered from the sample 10. An ion beam could also be provided instead of the electron beam 110. An additional detector for secondary electrons may also be provided (not shown). The electron column 106 preferably has its own vacuum housing 113 within the vacuum housing 102. The vacuum housing 113 is evacuated, for example, to a residual gas pressure of 10⁻⁷ mbar to 10⁻⁸ mbar. In this vacuum, the electron beam 110 travels from the electron source 108 until it exits the vacuum housing 113 at its bottom and then falls onto the sample 10.

[0032] The electron column 106, in conjunction with supplied process gases introduced externally by a gas supply unit 114 via a gas line 116 into the area of ​​a focal point of the electron beam 110 on the sample 10, can perform electron-beam induced processing (EBIP). This includes, in particular, the deposition of material onto and / or the etching of material from the sample 10. The system 100 also has a control computer 118, which appropriately controls the electron column 106, the sample stage 11, and / or the gas supply unit 114.

[0033] Furthermore, the system 100 includes a device 1 as described in the Fig. 1 and Fig. The device 1 is shown in Figure 2 and described above. It comprises an activatable or deactivatable cooling unit 3, which can be switched on and off, or opened and closed, by means of a movable enclosure 2 (insulation). When the cooling unit 3 is open or active, process gases 7 can be adsorbed on the cooling surface 4, thus enabling faster changes of the sample 10 and / or the process gases in the vacuum housing 102.

[0034] The insulation 2 can, for example, enclose a cavity with a rectangular wall or a cavity with a round wall and have a rotary closure.

[0035] A cooling device 3 (cold trap) can also contain several cooling surfaces 4, for example in a stacked arrangement, to increase the available surface area.

[0036] Depending on the application, the cooling surface 4 can be extended into and / or out of the insulation or covering 2, as shown in the Fig. 1 and Fig. 2 is shown.

[0037] Accordingly, either the cooling surface 4 can be moved by a mechanical drive and the insulation 2 is fixed, or the insulation 2 is moved by a mechanical drive and the cooling surface 4 is fixed. It is also possible for both the cooling surface 4 and the insulation to be moved by a mechanical drive.

[0038] The assembly can be equipped with sensors that detect the endpoint when the cooling surface 4 has fully extended into or out of the insulation. Additionally, a locking mechanism can be provided to ensure a tight seal of the insulation.

[0039] The design and operation are such that the risk of particle contamination on the workpiece being processed, e.g., a mask, is minimized. This allows the use of materials that generate as few particles as possible under mechanical stress. The relevant areas can also be partially enclosed with a protective device that captures any particles generated before they can reach the mask. The activation and deactivation of the cooling trap 3 preferably occurs when no photomask or workpiece is present on the sample stage 11. The process of the cooling surface 4 or the insulating enclosure 2 can also be controlled by a computer unit, in particular by the control computer 118 of the vacuum processing system 100.

[0040] One or more switchable cold traps 3 can be placed at several locations in the process or vacuum chamber or the vacuum housing 102. The assembly can be mounted and operated in such a way that the risk of particle contamination on the workpiece 10 being processed is minimized and the travel distance for the sample 10 (mask) being processed is not restricted. The function of other components in the vacuum chamber 102 must also not be impaired.

[0041] Accordingly, the device 1 with the switchable cooling device 3 can be arranged either on the chamber wall of the vacuum chamber 102, in the vicinity of the electron column 106, in the vicinity of the objective of the electron column 106 or on the sample stage 10 in the vicinity of the sample 10 (photomask).

[0042] A special embodiment is in Fig. Figure 4 shows that the insulating casing 2 is opened by means of a movable closure 8, which is actuated by a deflecting mirror 12 with a pin 9 mounted on the test stage 10, analogous to the device from German patent application DE 10 2020 124 307 A1, which, however, serves to actuate a shielding element. Nevertheless, the actuating mechanism from document DE 10 2020 124 307 A1 can be used in the same way for moving the insulation 2 or a closure 8, so that the disclosure content of DE 10 2020 124 307 A1 is fully incorporated herein in this respect.

[0043] The scheme is in Fig. Figure 4 shows the switching on and off of the insulating enclosure 2 using the sample stage 11 of the mask repair system 100. A prism 12 with a pin 9 is mounted on this stage. The pin 9 is threaded through an eyelet of the closure 8. In this way, the insulating enclosure 2 can be opened and closed to the vacuum chamber 102. The threading process can be monitored live with a CCD camera 119 via the mirror-polished surface of the prism 12.

[0044] Fig. Figure 4 shows an embodiment in which the cooling surface 4 is located in the vicinity of a gas nozzle of the vacuum processing system 100. In the example shown, the cooling device 3 is switched on using the sample stage 10.

[0045] This mounting location is advantageous because the capture of process gases after processing or repair takes place near the gas nozzle, i.e., the point of highest gas concentration. Furthermore, the height of sample table 10 and cooling device 3 or apparatus 1 can be adjusted to prevent unwanted contact with sample 10 when the sample 10 is brought close to the gas nozzle.

[0046] The cooling of the cooling surface 4 can be achieved by the following measures: Heat conduction through a cold reservoir 5, which is thermally connected to the cooling surface and contains a cryogen, e.g. liquid nitrogen, as in Fig. 1 and Fig. Figure 2 shows that cooling down to -196°C is possible with liquid nitrogen. This temperature is sufficient to condense many process gases. • Contact of liquid nitrogen with the cooling surface 4. Flow of cold gaseous nitrogen, which is cooled, for example, by liquid nitrogen. Thermoelectric cooling is achieved using an array of Peltier elements. Peltier elements can provide cooling down to a temperature difference of up to 70°C relative to the ambient temperature. Therefore, at an ambient temperature of 20°C, the cooling surface can be cooled down to -45°C.

[0047] In a preferred embodiment, the cooling device 3 can be equipped with a heating function. This allows the cooling surface to be heated to > 0°C, preferably > 50°C, in order to desorb adsorbed gas molecules.

[0048] The vacuum processing system 100 and the device 1 with switchable cooling device 3 can be operated in different ways. Example 1

[0049] The following steps can be performed one after the other in the order given: 1. Performing a mask repair with the supply of process gas to vacuum chamber 102 2. Completion of the repair 3. Termination of the process gas supply 4. Activating the cooling device 3 (cold trap) by opening the insulation 2 5. Isolating the cold trap 3 from the vacuum chamber 102 6. Carrying out another repair Example 2

[0050] The following steps can be performed one after the other in the order given: 1. Performing a mask repair with the supply of process gas to vacuum chamber 102 2. Completion of the repair 3. Termination of the process gas supply 4. Activating the cooling device 3 (cold trap) by opening the insulation 2 5. Unloading the first mask 6. Loading a second mask 7. Isolating the cold trap 3 from the vacuum chamber 102 8. Carrying out the mask repair Example 3

[0051] The following steps can be performed one after the other in the order given: 1. Activating the cooling device 3 (cold trap) by opening the insulation 2 2. Adsorption of process gas 3. Spatial isolation of the cooling surface 4 by closing the insulation 2 4. Heating the cooling surface 4 and pumping out desorbed gas molecules 5. Cooling the cooling surface 4 6. Activating the cooling device 3 (cold trap) by opening the insulation 2

[0052] A corresponding repair process may include the following steps: Electron beam-induced deposition of material starting from a precursor gas. • Electron beam-induced etching of mask material using a precursor gas.

[0053] Exposure of the photomask with a precursor gas without the use of an electron beam. The cooling surface can be used to condense the following precursor molecules after a repair process: Separation gases: • (Metal, transition element, main group) alkyls such as cyclopentadienyl (Cp)- or methylcyclopentadienyl (MeCp)-trimethylplatinum (CpPtMe3 or MeCpPtMe3), tetramethyltin SnMe4, trimethylgallium GaMe3, ferrocene Cp2Fe, bis-aryl-chromium Ar2Cr and other such compounds. • (Metal, transition element, main group) carbonyls such as chromium hexacarbonyl Cr(CO)6, molybdenum hexacarbonyl Mo(CO)6, tungsten hexacarbonyl W(CO)6, dicobalt octacarbonyl Co2(CO)8, triruthenium dodecacarbonyl Ru3(CO) 12 , iron pentacarbonyl Fe(CO)5 and other such compounds. • (Metal, transition element, main group) alkoxides such as tetraethoxysilane Si(OC2H5), tetraisopropoxytitanium Ti(OC3H7)4 and other such compounds. • (Metal, transition element, main group) halides such as WF6, WCl6, TiCl6, BCl3, SiCl4 and other such compounds. • (Metal, transition element, main group) complexes such as copper bis-hexafluoroacetylacetonate Cu(C5F6HO2)2, dimethyl gold trifluoroacetylacetonate Me2Au(C5F3H4O2) and other such compounds. • Organic compounds such as CO, CO2, aliphatic or aromatic hydrocarbons, components of vacuum pump oil, volatile organic compounds and other such compounds. Usable auxiliary gases: Oxidizing agents such as O2, O3, H2O, H2O2, N2O, NO, NO2, HNO3 and other oxygen-containing gases. Halides such as Cl2, HCl, XeF2, HF, I2, HI, Br2, HBr, NOCl, PCl3, PCl5, PF3 and other halogenated gases. Reducing gases such as H2, NH3, CH4 and other hydrogen-containing gases.

[0054] The substances listed are not an exhaustive list, but are only examples.

[0055] Although the present invention has been described in detail with reference to the exemplary embodiments, it is obvious to those skilled in the art that the invention is not limited to these exemplary embodiments, but rather that modifications are possible in such a way that individual features can be omitted or different combinations of features can be implemented without departing from the scope of protection of the appended claims. In particular, the present disclosure includes all combinations of the individual features shown in the various exemplary embodiments, so that individual features that are only described in connection with one exemplary embodiment can also be used in other exemplary embodiments or in combinations of individual features not explicitly shown. REFERENCE MARK LIST 1 Device 2 Insulation or covering 3 Cooling device or cold trap 4 cooling surfaces 5 cold storage tanks 6 pump 7 adsorbed process gas 8 Closure 9 pen 10 Sample or workpiece to be processed or mask 11 Sample table 12 deflecting mirrors 100 vacuum processing systems 102 vacuum housings 104 Vacuum pump 106 electron column 108 electron source 110 electron beam 112 Electron microscope 113 Vacuum housings 114 Gas supply unit 116 Gas pipeline 118 tax calculators 119 Camera QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 9 799 490 B2

[0013] DE 10 2020 105 706 B4

[0013] DE 10 2020 124 307 A1

[0042]

Claims

Device for removing process gases from vacuum processing systems (100), in particular electron beam systems for fault identification during and / or repair of lithography masks, with a cooling device (3) having at least one cooling surface (4) for adsorption or condensation of process gases, characterized in that the device comprises a thermal insulation (2) of the cooling surface (4) of the cooling device (3) from the environment, which is activatable and deactivatable. Device according to claim 1, characterized in that the activatable and deactivatable thermal insulation (2) is a covering (2) or a movable closure (8) relative to the cooling device (3), wherein the covering (2) or the closure (8) is movable, in particular displaceable, between a first position in which the space around the cooling surface (4) of the cooling device (3) is closed and the thermal insulation (2) is activated, and a second position in which the space around the cooling surface (4) of the cooling device (3) is open and the thermal insulation (2) is deactivated. Device according to claim 2, characterized in that the device comprises a drive, in particular a mechanical drive for moving the covering (2) or the closure (8) and / or the cooling device (3) or parts thereof. Device according to one of the preceding claims, characterized in that the device comprises an evacuation and / or flushing device (6) for evacuating a space surrounded by the thermal insulation (2) and / or for flushing the space surrounded by the thermal insulation (2) with a gas or a fluid. Device according to one of the preceding claims, characterized in that the at least one cooling surface (4) of the cooling device (3) can be cooled by heat conduction in conjunction with a cold reservoir (5), by contact with a cooling medium or by thermoelectric cooling with one or more Peltier elements. Device according to one of the preceding claims, characterized in that at least one cooling surface (4) of the cooling device (3) is designed to be heated. Vacuum processing system, in particular electron beam systems for fault identification during and / or repair of lithography masks, comprising a vacuum chamber (102) for receiving a workpiece (10) to be processed and a gas supply device (114) with which at least one process gas can be provided in the vacuum chamber (102) before and / or during processing of a workpiece (10), and comprising at least one device (1) according to one of the preceding claims. Vacuum processing system according to claim 7, characterized in that the vacuum processing system (100) is a mask repair system for repairing lithography masks, in particular masks for EUV lithography. Method for operating a vacuum processing system (100), in particular a vacuum processing system (100) according to one of claims 7 to 8, in which, after completion of processing a workpiece (10) in a vacuum chamber (102) of the vacuum processing system (100), a supply of process gas to the vacuum chamber (102) is stopped and a cooling device (3) with an activatable and deactivatable thermal insulation (2) is activated by deactivating the thermal insulation for adsorption or condensation of process gas, in order to subsequently reactivate the thermal insulation (2) and carry out further processing of one or the workpiece (10). Method according to claim 9, characterized in that the workpiece (10) to be processed is changed during the deactivation of the thermal insulation (2). Method according to claim 9 or 10, characterized in that after the adsorption or condensation of process gas on at least one cooling surface (4) of the cooling device (3) during the activation of the thermal insulation (2), the cooling surface (4) of the cooling device (3) is heated and / or a space surrounded by the thermal insulation (2) is purged and / or evacuated.

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