Apparatus and method for processing at least one semiconductor substrate

Abstract

There is provided a device (200) for processing at least one semiconductor substrate (281), the device (200) having: a reactor (220) having a wall that defines a reaction space (221); a locking structure (230) configured to load the reaction space (221) with at least one semiconductor substrate (281) and unload the at least one semiconductor substrate (281) from the reaction space (221) and to lock the reaction space (221) impermeable to hydrofluoric acid; and a heating device (210) configured to set at least one predefined temperature within at least one temperature range in the reaction space (221). The device further has: a gas inlet (240, 250) configured to supply hydrofluoric acid in vapor form to the reaction space (221); a gas outlet (260) configured to discharge hydrofluoric acid in vapor form from the reaction space (221); and a gas supply system (270) coupled to the gas inlet (240, 250) and configured to supply hydrofluoric acid in vapor form to the gas inlet (240, 250) at the predefined temperature.

Description

Field of the Invention

[0001] The present invention relates to a device and a method for processing at least one semiconductor substrate. Background Art

[0002] In the automotive field, with the continued development towards electric vehicles, solutions for power semiconductors for fast and lossless switching are required. Here, the trend towards synchronization from lateral components to vertical components and the trend from the silicon technology established for decades towards so-called "wide bandgap" materials, such as silicon carbide (SiC) or gallium nitride (GaN), has led to the development of new component designs and production processes.

[0003] In the case of SiC, whenever possible, equipment from silicon technology is preferably used. This thus results in cost savings in terms of investment costs through synergistic effects. Independently of this, the selected equipment and processes, especially high-temperature processes (such as oxidation and dopant activation), are tailored specifically for silicon carbide.

[0004] To manufacture power semiconductor components made of silicon carbide, known in the literature as "FinFETs", very thin, free-standing structures (semiconductor fins) with a thickness in the range of 100 nm to 200 nm are required. Here, a possible and simple manufacturing process setup involves generating a structured grid by means of a suitable dry etching process. However, this process alone is insufficient for the generation of thin structures, so that the structures generated in the corresponding grid are further thinned in a subsequent fin formation process ("fin-forming process"). This method involves cyclic oxidation and subsequent removal of the generated SiC oxide, for example, in a bath with an aqueous hydrofluoric acid solution. This sequence of steps is carried out successively several times depending on the initial grid and the desired final thickness of the semiconductor fins. This results in logistical processing costs, transfer costs, and equipment management costs. Summary of the Invention

[0005] The object of the present invention is to provide a device and a method by means of which one or more semiconductor substrates can be processed more cost-efficiently. This enables more cost-efficient manufacture of semiconductor structural elements, such as vertical field-effect transistors, such as FinFETs.

[0006] According to one aspect of the present invention, this object is solved by a device for processing at least one semiconductor substrate. The device has a reactor, which has: a wall that delimits a reaction space; a locking structure that is arranged for loading at least one semiconductor substrate into the reaction space and unloading at least one semiconductor substrate from the reaction space and for being impermeable to hydrofluoric acid A reaction space that can be locked; and a heating device configured to adjust to at least one predetermined temperature within at least one temperature range in the reaction space. The device further has: a gas inlet configured to supply hydrofluoric acid in vapor form to the reaction space; a gas outlet configured to discharge hydrofluoric acid in vapor form from the reaction space; and a gas supply system coupled to the gas inlet and configured to supply hydrofluoric acid in vapor form to the gas inlet at a predetermined temperature. This achieves minimizing the overall logistical costs and the optional waiting time for the equipment to be ready.

[0007] According to a further aspect of the invention, this task is solved by a method for processing at least one semiconductor substrate by means of a device constructed according to the aspects described above. The method has: a cycle having thermally oxidizing at least one semiconductor substrate in the reaction space and subsequently removing a part of the oxidized semiconductor material of at least one semiconductor substrate by means of hydrofluoric acid supplied by the gas inlet, wherein the cycle runs at least twice, and wherein the locking structure remains locked from the start of the first run of the cycle until the end of the last run of the cycle. This achieves minimizing the overall logistical costs and the optional waiting time for the equipment to be ready. For example, in a method for manufacturing FinFETs, a complete fin shaping process is achieved in one device in one method step, whereby investment costs and equipment costs can be saved. In addition, multiple replacements of the equipment can be prevented or reduced, and thus logistical costs are reduced and production time is saved. Furthermore, in combination with a surface mask for "fin shaping" of semiconductor fin geometries, better process inspection can be achieved. In addition, the device can provide a tool for the "morphology shaping" described in detail. Description of the Drawings

[0008] Expansion schemes of these aspects are set forth in the dependent claims and the description. Embodiments of the invention are shown in the drawings and are explained in more detail below. The drawings show:

[0009] Figure 1 A schematic diagram showing the flow of a method for processing at least one semiconductor substrate;

[0010] Figure 2 Schematic diagrams showing devices for processing at least one semiconductor substrate according to different embodiments; and

[0011] Figure 3 Flowcharts showing methods for processing at least one semiconductor substrate according to different embodiments. Detailed Description of the Invention

[0012] In the following detailed description, reference is made to the accompanying drawings, which form a part of this specification and in which specific embodiments are shown for purposes of illustration only, in which the present invention may be applied. It goes without saying that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. It goes without saying that the features of the different embodiments described herein may be combined with each other as long as not specifically stated otherwise. Therefore, the following detailed description should not be understood in a limiting sense, and the scope of the present invention is defined by the appended claims. In the drawings, the same or similar elements are provided with the same reference numerals as long as this is expedient.

[0013] A possibility for generating thin semiconductor fins (lateral structural width of 100 nm to 200 nm) in a FinFET lies in the cyclic sequence of oxidizing and removing the generated oxide, as schematically illustrated in Figure 1 As such. Here, a corresponding initial first grid is structured in the semiconductor substrate, for example, a trench structure (groove structure) in a SiC substrate. Starting from this profile, an oxidation process follows, for example, an oxidation process in a high-temperature oxidation device 100. The high-temperature oxidation device 100 has a reactor 110 made of quartz or silicon carbide, an adjustable heating device 111, a device 130 to a gas supply unit, and a silicon carbide substrate 120 in a holder or substrate carrier (also referred to as a boat (Boot)) during the process and during substrate processing.

[0014] After oxidation and transfer 140 of the semiconductor substrate, the oxide is removed wet-chemically in a solution 160 containing hydrofluoric acid, conventionally, for example, in a dipping tank 150. Due to the self-limiting nature of the oxide during the oxidation process, for economic reasons but also from a process technology perspective, it may be advantageous and necessary to run the process in multiple cycles, as indicated by arrows 140 and 140' (etching or removal and transfer). This results in repeated additional costs in terms of logistics and optional time delays due to the necessary equipment changeovers in 140 and 140'.

[0015] For this process, it is essentially immaterial whether it involves a vertical oxidation device or a horizontal oxidation device. Alternatively, the furnace may be arranged in a horizontal embodiment, as schematically illustrated in Figure 2 As such.

[0016] Figure 2Schematic illustration of a device 200 for processing at least one semiconductor substrate 281 according to different embodiments. The device 200 has a reactor 220, gas inlets 240, 250, a gas outlet 260, and a gas supply system 270.

[0017] The reactor 220 has a wall, a locking structure 230, and a heating device 210. The wall defines a reaction space 221. The locking structure 230 is configured to load and unload one or more semiconductor substrates 281 into and from the reaction space 221 and to seal the reaction space 221 in a hydrofluoric acid-impermeable manner. The heating device 210 is configured to set a predetermined temperature within at least one temperature range in the reaction space 221. The predetermined temperature is higher than room temperature or may be higher than the temperature at which the reaction space 221 is loaded with the semiconductor substrate 281. The heating device 210 may be configured to set the predetermined temperature in the reaction space 221 to a temperature within a first temperature range (in which at least one semiconductor substrate is at least thermally oxidized), for example, within a temperature range extending from about 900 °C to 1400 °C. In addition, the heating device 210 may be configured to set the predetermined temperature in the reaction space 221 to a temperature within a second temperature range extending from about 60 °C to about 600 °C, for example, 200 °C to 400 °C.

[0018] The gas inlets 240, 250 are at least configured to supply hydrofluoric acid in vapor form (hydrofluoric acid vapor) to the reaction space 221. The gas outlet 260 is configured to discharge hydrofluoric acid in vapor form from the reaction space 221. The gas supply system 270 is coupled to the gas inlets 240, 250 and is configured to supply at least hydrofluoric acid in vapor form to the gas inlets 240, 250 at a predetermined temperature.

[0019] In addition, the wall, the locking structure 230, the gas inlets 240, 250, and the gas outlet 260 may be configured such that hydrofluoric acid in vapor form is supplied from the gas supply system 270 to the gas inlets 240, 250 at a predetermined temperature. The wall, the locking structure 230, the gas inlets 240, 250, and the gas outlet 260 may each be made of a non-oxidizing or low-oxidizing material that is hydrofluoric acid-resistant or substantially hydrofluoric acid-resistant.

[0020] In addition, the device 200 may have a cold trap 290 that is coupled to the gas outlet 260. The cold trap 290 may be coupled to the gas supply system 270 such that liquid hydrofluoric acid is supplied from the cold trap 290 to the gas supply system 270. The cold trap 290 may have a detection device 292 configured to detect hydrofluoric acid.

[0021] In addition, the apparatus 200 may have a vacuum pump system which is coupled to the reactor 220 such that a low pressure or a vacuum can be established in the reaction space 221.

[0022] The heating device 210 may be arranged outside the reaction space of the reactor. The reactor may have, for example, a muffle furnace, where the reaction space 221 is a combustion material chamber and the walls are the muffle furnace. In the simplest case, the heating device may be a resistance heating device. It may be divided into multiple zones. Thermocouples may be arranged at appropriate positions, and the corresponding heating control device may ensure the desired temperature distribution on the tube. Due to the calibration of the internal temperature and the external temperature, the internal thermocouples may be omitted.

[0023] The wall may be configured as a tube or a process tube. In the furnace, a process tube made of silicon carbide or made of a non-oxidizing and hydrofluoric acid-resistant material (such as ceramics) may be provided. The process tube has a corresponding door locking device or tube locking device (that is, a locking structure) for loading or unloading a semiconductor substrate into or from the process tube. Alternatively, a tube made of silicon carbide with an internal tube (also referred to as a "liner") may also be used. The liner may be made of, for example, silicon carbide, ceramics, or sintered boron nitride or the like. This can increase the service life of the apparatus.

[0024] The gas inlets 240, 250 may have one or more gas nozzles 240, 250 which are arranged to disperse at least hydrofluoric acid in vapor form in the reaction space.

[0025] The reactor 220 and all hot components exposed to the process gas (for example, the locking structure 230, the gas nozzles 240 or 250, the area of the gas outlet 260, and the substrate carrier 280 drawn into the reactor) may be produced from silicon carbide or alternatively completely or partially produced from ceramics or coated with ceramics. Alternatively, if other materials are correspondingly suitable for achieving the process temperatures used (for example, up to 1350 °C) and the gas environment (nitrogen, argon, nitrous oxide, oxygen, dry and wet (with water), and a vapor phase containing hydrofluoric acid), then these other materials may be considered.

[0026] In different embodiments, the gas supply system 270 has a large number of valves 271, 272, 273, 274, 275, 276, 277, 27n and steam pressure saturators (also referred to as bubblers) 278, 2710. Different process gases can be introduced directly and / or by means of a carrier gas into the reaction space 221 using the valves 271, 272, 273, 274, 275, 276, 277, 27n. The regulation of the valves can be programmed with a corresponding control device having a correspondingly computer-readable medium.

[0027] For example, nitrogen can be used as a carrier gas, which is introduced into the reaction space 221 by means of the bubbler 278 with, for example, dichloroethylene (DCE) or deionized (DI) water 279. Alternatively or additionally, the carrier gas (for example nitrogen) can be directed via the bubbler 2710 through a solution containing hydrofluoric acid and then the carrier gas can be conducted into the reactor space 221 together with the hydrofluoric acid carried by the carrier gas.

[0028] The pipeline guiding device of the gas supply system 270 can be provided with a chemically resistant hose (for example made of a material containing polytetrafluoroethylene) outside the region loaded with a temperature (T < 60 °C).

[0029] The cold trap 290 can be connected to the gas supply system 270 by means of a reflux pipe 2712. The cold trap 290 is provided for cooling the hydrofluoric acid-containing components from the exhaust gas. Liquid hydrofluoric acid can return from the cold trap 290 via the valve 291 and the reflux pipe 2712 to the corresponding bubbler 2710.

[0030] The reflux pipe 2712 is implemented chemically resistant or correspondingly coated. Furthermore, from a safety technology perspective, the cold trap 290 can include a detection device 292 for hydrofluoric acid or hydrofluoric acid vapor, for example a sensor unit and an analysis and utilization unit.

[0031] Figure 3 A flow chart of a method 300 for processing at least one semiconductor substrate according to different embodiments is shown. The method 300 can be carried out with the previously described device 200.

[0032] The method 300 can include loading 310 the reaction space with at least one semiconductor substrate and closing the locking structure. The locking structure is closed such that the contact area of the reaction space or the wall and the locking structure are hermetically sealed relative to hydrofluoric acid in vapor form.

[0033] In addition, method 300 has a cycle 350. Cycle 350 has at least one thermal oxidation 320 of a semiconductor substrate in a reaction space and subsequent removal 330 of a part of the oxidized semiconductor material of at least one semiconductor substrate by means of hydrofluoric acid conveyed by a gas inlet. Cycle 350 runs at least twice. Cycle 350 can be repeated so frequently until a pre-given material removal from at least one semiconductor substrate is achieved.

[0034] In addition, method 300 can have an opening of a locking structure and unloading 340 of at least one semiconductor substrate from the reaction space. Before opening the locking structure, the method can have a detection of hydrofluoric acid in the gas received from the gas outlet. If hydrofluoric acid cannot be detected in the gas received from the gas outlet, the locking structure can be opened for opening.

[0035] Intuitively, the locking structure remains locked from the first run of cycle 350 until the end of the last run of cycle 350.

[0036] The purpose of the "fin forming process" in manufacturing FinFETs is to generate vertical structures with a thickness of 100 - 200 nanometers by means of cyclic oxidation and subsequent removal of the formed oxide. This cyclic oxidation and subsequent removal of the formed oxidized silicon carbide is performed in situ in the reaction space of the device in a coherent process sequence.

[0037] Then, the method has oxidation and removal of a semiconductor oxide formed by oxidation (for example, oxidation of a silicon carbide substrate and removal of the oxidized silicon carbide from the silicon carbide substrate).

[0038] At the starting point of the method, there is a silicon carbide substrate in the form of a wafer, which has a structured grid (groove structure or trench structure). The grid can be generated with a corresponding structured depth in a dry etching process.

[0039] The semiconductor substrate used (for example, a wafer with a thickness in the range of several hundred micrometers) is held in a substrate carrier (so-called "boat") during the complete process sequence. The substrate carrier can be made of silicon carbide or ceramic (such as boron nitride).

[0040] The substrate carrier can be moved into the reactor or into an internal "liner" (made of SiC or ceramic) by means of a mechanical loading device and placed therein. This can already be done at a standby temperature from room temperature up to several hundred degrees Celsius (for example, in the range of 60°C to 600°C, for example 400°C to 600°C).

[0041] After loading 310, the reaction space is locked by means of a locking structure such that no hydrofluoric acid can inadvertently leak out of the reaction space.

[0042] The reaction space can be flushed with nitrogen by means of a gas supply system. Optionally, a combination consisting of a pumping cycle and a flushing cycle can be run by means of an optional vacuum pump system during heating the reaction space to a pre-given temperature (process temperature) by means of a heating device. In the simplest case, the semiconductor substrate is flushed in an inert or slightly oxidized gas environment during heating the reaction space to the process temperature. For this purpose, the gas supply system can supply the necessary gas to the gas inlet, such as nitrogen (N2), argon (Ar), or N2 with 1% oxygen (O2).

[0043] After reaching the process temperature for oxidation (for example, in the case of a silicon carbide substrate, 1000 °C - 1350 °C) and subsequent temperature stabilization, the inert gas phase can be replaced by an oxidizing gas phase by means of the gas supply system.

[0044] The oxidizing gas phase can be a dry or wet oxidation with or without additional chlorine, for example provided by a bubbler with trans-1,2-dichloroethylene (Trans-LC) or a substance with similar properties (such as DCE).

[0045] For example, oxygen and oxygen as a carrier gas can be used by a bubbler (278) with DI water (279) (see Figure 2 ). The oxidation can be terminated after a correspondingly set oxidation time. The reaction space can be flushed with an inert gas. Corresponding to the known and / or pre-determined oxidation rate and oxidation time, a part of the silicon carbide of the semiconductor substrate can be oxidized and exist as silicon carbide oxide.

[0046] Subsequently, the reactor can be flushed with an inert gas and adjusted to the process temperature for the oxide etching step.

[0047] The removal of the oxide of at least one semiconductor substrate is carried out in a gas environment containing hydrofluoric acid. The process temperature can be maintained, for example, at the oxidation temperature (for example, in the range of 1000 °C to 1350 °C). Alternatively, for example, to optimize process control, the pre-given temperature for the etching step can also be lower, for example, a temperature in the temperature range from about 200 °C to about 400 °C.

[0048] The necessary etching time can be determined in advance according to the oxide thickness, process temperature, and the delivered amount of the vaporous hydrofluoric acid-containing solution and set accordingly for the process.

[0049] Hydrofluoric acid in vapor form can be supplied to the reaction space by a gas supply system. To this end, a carrier gas (e.g., N2) can be directed via a bubbler system (2710) through an aqueous solution containing hydrofluoric acid (see Figure 2 ). A carrier gas flow (in the range of several hundred standard cubic centimeters per minute up to several standard liters per minute) can be introduced into the reaction space via a gas supply system and a gas nozzle of a gas inlet. A certain amount of hydrofluoric acid carried along with the carrier gas flow can be released in the hot reaction space in the form of vapor from the gas nozzle at the location of the substrate carrier. The hydrofluoric acid can then etch previously oxidized areas of the silicon carbide wafer.

[0050] All hot surfaces that come into contact with the hydrofluoric acid vapor can or should be produced from resistant silicon carbide, the oxide of which can also be etched. The loss of oxidized SiC components can be kept low by suitable gas guidance, the use of ceramic linings (walls) and areas lined with ceramic, and also by adjusted temperature profiles and adjusted quantities. Alternatively, the hot surfaces can be made of inert ceramics (e.g. boron nitride).

[0051] The remaining gas flow containing hydrofluoric acid can be fed from the reaction space via the gas outlet through the cold trap to the suction device.

[0052] The cold trap can also be implemented in multiple stages corresponding to the distillation column.

[0053] All (cool) components outside the range (approximately) above the process temperature (eg T<60° C.) can accordingly be embodied with a hydrofluoric acid-resistant coating (eg polytetrafluoroethylene or the like) or can be intrinsically resistant to hydrofluoric acid.

[0054] The cold trap may have a reflux device and / or a reflux line for condensed hydrofluoric acid vapor or liquid hydrofluoric acid. Depending on the concentration, the hydrofluoric acid liquefied in the cold trap may be conveyed back to the container (2711) of the bubbler system (2710) of the gas supply system by means of a reflux line (2712) (see Figure 2 ).

[0055] The cold trap can have a detection device (292) with a sensor for hydrofluoric acid and an analytical utilization unit (see Figure 2 ). The detection device can be arranged at a plurality of different positions and thus ensure an effective rinsing step before a subsequent process step of oxidation or before unloading the processed semiconductor substrate from the reactor.

[0056] Depending on the necessary and desirable thinning of the vertically oriented silicon carbide structure, the processing of the semiconductor substrate can run through multiple cycles 350 in terms of the overall process duration. For this case, after the etching process and after flushing the gas environment containing hydrofluoric acid from the reaction space by means of an inert gas, a renewed oxidation process can be started (see above), followed by a renewed etching step, etc. Here, the number and duration of the cycles 350 are not restricted but can be freely selected.

[0057] After the desired oxide thickness has been produced and its etching has ended, the reaction space can be flushed with an inert gas (such as N2 or Ar). In addition, a pre-given unloading temperature can be set. By means of a sensor for detecting the hydrofluoric acid concentration of the device, it can be checked and ensured that the reaction space is effectively flushed before the reaction space is opened and the substrate carrier with the semiconductor substrate is unloaded 340. Additional evacuation devices and sensors can be provided in the opening area in order to comply with safety regulations.

[0058] In different embodiments, a pre-treatment of the device can be carried out before a further process. For example, for the reproducibility of the process result, it may be advantageous if all components made of silicon carbide have a base oxide layer. Then, the base oxide layer can be etched cyclically in order to be produced again in the oxidation step.

[0059] Such a "base oxide layer" can be achieved, for example, by oxidation without a wafer. The components made of silicon carbide can be arranged such that the material loss caused by back-etching is taken into account. For example, a spare thickness can be provided in the component in order to ensure a sufficient service life of the component.

[0060] Optionally, by means of a suitable process gas guidance and corresponding gas quantity management in the area of the gas nozzle, the spare thickness can be maintained only locally or point by point. Alternatively, a tube ("liner") can be used, which is arranged in the reactor as a muffle furnace. After its service life, it may only be necessary to replace the liner. The service life can also be increased by a corresponding material selection. Thus, the substrate carrier and other components can be made entirely or partly of ceramics or, for example, sintered boron nitride.

[0061] In addition, a ceramic liner can be provided in the "hot area" of the reaction space. Alternatively, a gas nozzle with ceramic cooling tubes or with a ceramic coating can be used. Alternatively, a silicon carbide liner with a spare thickness can be provided, which is deliberately consumed and replaced daily and increases the service life of the tube.

[0062] In various embodiments, in addition to the structured grid, a shaped mask can also be provided on the semiconductor substrate as part of the substrate pretreatment. A corresponding mask material can be provided so as to be able to withstand oxidation processes and / or etching processes. In the case of a silicon carbide substrate, the mask structure can consist of silicon nitride, which is formed in a low-pressure chemical vapor deposition (LPCVD) process. Silicon nitride has a low self-locking oxidation rate and has a significantly lower etching rate in hydrofluoric acid than silicon oxide.

[0063] For the use in the previously described device and the previously described method, it may be advantageous not to use a continuous, integrated silicon nitride layer as a mask structure. Instead, a layer stack consisting of alternating silicon nitride and silicon-rich nitride, ending with silicon nitride, can be used as a mask structure. Silicon nitride has a lower oxidation rate during oxidation and silicon-rich nitride has a lower etching rate due to its higher adjustable silicon content and thus has a higher resistance to vapors containing hydrofluoric acid. By means of adjusting the layer thickness of the silicon-rich silicon nitride layer and the silicon nitride layer, a thin and cost-effectively shaped mask structure is generally possible. The layer stack of silicon nitride layers and silicon-rich silicon nitride layers can be manufactured by gas flow changes in the LPVCD process. The silicon-rich silicon nitride layer has a higher silicon content than the silicon nitride layer.

[0064] The embodiments described and shown in the drawings are selected only as examples. Different embodiments can be combined with each other completely or in terms of individual features. An embodiment can also be supplemented by features of other embodiments. In addition, the described method steps can be implemented repeatedly and in a sequence different from the described sequence. In particular, the present invention is not limited to the specified method.

Claims

1. An apparatus (200) for processing at least one semiconductor substrate (281), the apparatus (200) having: A reactor (220), the reactor having: - A wall that defines a reaction space (221); - A locking structure (230) configured to load at least one semiconductor substrate (281) into the reaction space (221), unload the at least one semiconductor substrate (281) from the reaction space (221), and lock the reaction space (221) against hydrofluoric acid; And - A heating device (210) configured to set at least one predefined temperature within at least one temperature range in the reaction space (221); A gas inlet (240, 250) configured to supply hydrofluoric acid in vapor form to the reaction space (221), A gas outlet (260) configured to discharge hydrofluoric acid in vapor form from the reaction space (221); And A gas supply system (270) coupled to the gas inlet (240, 250) and configured to supply hydrofluoric acid in vapor form to the gas inlet (240, 250) at the predefined temperature, wherein the heating device (210) is configured to set the predefined temperature in the reaction space (221) to a temperature within a first temperature range in which the semiconductor substrate is at least thermally oxidized.

2. The apparatus (200) according to claim 1, Among them, wherein the heating device (210) is configured to set the predefined temperature in the reaction space (221) to a temperature within a temperature range extending from 900 °C to 1400 °C.

3. The apparatus (200) according to claim 1 or 2, Among them, wherein the heating device (210) is further configured to set the predefined temperature in the reaction space (221) to a temperature within a second temperature range extending from 60 °C to 400 °C.

4. The apparatus (200) according to claim 1 or 2, Among them, wherein the wall, the closure structure (230), the gas inlet (240, 250), and the gas outlet (260) are further configured such that hydrofluoric acid in vapor form is supplied from the gas supply system (270) to the gas inlet (240, 250) at the predefined temperature.

5. The apparatus (200) according to claim 1 or 2, Among them, wherein the wall, the closure structure (230), the gas inlet (240, 250), and the gas outlet (260) are each made of a non-oxidizing and hydrofluoric acid-resistant material.

6. The apparatus (200) according to claim 1 or 2, the apparatus further having a cold trap (290) coupled to the gas outlet (260).

7. The apparatus (200) according to claim 6, wherein, The cold trap (290) is coupled to the gas supply system (270) such that liquid hydrofluoric acid is supplied from the cold trap (290) to the gas supply system (270).

8. The apparatus (200) according to claim 6, Among them, wherein the cold trap (290) has a detection device (292) configured to detect hydrofluoric acid.

9. The device (200) according to claim 1 or 2, the device further having a vacuum pump system, the vacuum pump system being coupled to the reactor (220) such that a low pressure or a vacuum can be set in the reaction space (221).

10. A method (300) for processing at least one semiconductor substrate (281) by means of the device (200) according to any one of claims 1 to 9, the method (300) having: A cycle (350), the cycle having a thermal oxidation (320) of the at least one semiconductor substrate in the reaction space (221) and subsequently removing (330) a part of the oxidized semiconductor material of the at least one semiconductor substrate by means of hydrofluoric acid conveyed via the gas inlets (240, 250), wherein, performing the cycle at least twice; wherein the locking structure (230) remains locked from the start of the first run of the cycle until the end of the last run of the cycle.

11. The method (300) according to claim 10, Among them, the at least one semiconductor substrate (281) having a mask structure, wherein the mask structure has a layer stack composed of a silicon nitride layer and a silicon-rich silicon nitride layer.

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