Process reactor and method for producing structures on a substrate

Abstract

The invention relates to a process reactor (10) for the production of structures on a substrate (12) by means of plasma etching with atomic precision and / or plasma-assisted deposition of atomic layers. The process reactor (10) comprises a reaction chamber (16), a table (18) and / or a holder for the substrate (12) in the reaction chamber (16). A gas supply (31) evenly wets the substrate (12) with gas in the reaction chamber (16), with the gas supply (31) consisting of a gas injector (32) comprising a conduit ring (34) with nozzles. The substrate (12) to be processed can be arranged centrally in the conduit ring (34). A pump (60) evacuates the reaction chamber (16). The invention also relates to a method for producing structures on a substrate in a process reactor.

Description

[0001] PROCESS REACTOR AND METHOD FOR THE PRODUCTION OF STRUCTURES ON A SUBSTRATE

[0002] Technical area

[0003] The invention relates to a process reactor for the production of structures on a substrate by means of plasma etching with atomic precision and / or plasma-assisted deposition of atomic layers, comprising: a) a reaction chamber, b) a table and / or holder for the substrate in the reaction chamber, c) a gas supply which uniformly wets the substrate with gas in the reaction chamber, wherein the gas supply consists of a gas injector which comprises a conduit ring with nozzles in which the substrate to be processed can be centrally arranged; d) a pump for evacuating the reaction chamber.

[0004] Furthermore, the invention relates to a method for producing structures on a substrate in a process reactor.

[0005] Description

[0006] Process reactors are used in plasma etching (ALE) and plasma-enhanced deposition (PEALD) of individual atomic layers on a substrate. During deposition, the individual atomic layers are applied to the substrate, such as a semiconductor, using the ALD (Atomic Layer Disposition) or PEALD (Plasma Enhanced ALD) process. This allows the creation of tiny structures or dopings on a substrate, such as those required in industrial chip manufacturing.

[0007] In the PEALD technique, the substrate reacts in a sequential sequence with suitable reaction partners, also called "precursors." This sequential sequence allows precise control of the layer thickness of the atomic layers.

[0008] The PEALD process can be simplified as follows: First, the cleaned surface of the substrate is exposed to a first reactant (usually without plasma) in the reaction chamber of the process reactor. The substrate is often a disk-shaped semiconductor, also referred to as a wafer. It is necessary for adsorption on the surface to be controlled by a self-limiting process. The choice of the appropriate precursor (reactant) is crucial. This prevents more than a monolayer of the first reactant from being adsorbed, regardless of the amount of gas available. Subsequently, the residues of the first reactant are flushed out of the reaction chamber of the process reactor or pumped out using a pump. This prevents a gas-phase reaction with a second reactant.The latter is then passed over the substrate surface in a further step and, in conventional ALD, is reacted using thermal energy. This usually requires a so-called purge cycle in the process reactor.

[0009] The reactivity of the reactants with the substrate can be significantly increased by using a plasma. The plasma is created, for example, by the interaction of an alternating electric field in a capacitively coupled system.

[0010] In this process, it is desirable for the reactants to react with the substrate as uniformly and evenly as possible, both temporally and spatially. PEALD system technology is inherently complex, as the gas flow and other flow-dynamic systems must also accommodate the uniform coupling of RF power (RF = radio frequency).

[0011] Atomic Layer Etching (ALE) is a technique that enables the removal of individual atomic layers. It involves a sequence of chemical modification steps that are as self-limiting as possible and affect only the topmost atomic layer of the substrate. Further etching steps are performed that affect only the chemically modified areas by applying ions with appropriately dosed ion energy. This process requires complex gas handling (inlet and pumping) to achieve removal rates of one atomic layer.

[0012] For PEALD deposition and ALE etching in a process reactor, flow dynamics are an important parameter, especially for the required uniformity. Therefore, the gas must be introduced into the reaction chamber of the process reactor as evenly and symmetrically as possible.

[0013] Different process reactors are used for plasma etching (ALE) and plasma-enhanced deposition (PEALD). The integration of plasma etching (ALE) and plasma-enhanced deposition (PEALD) in a single process reactor—i.e., performing both processes in a single process reactor—can significantly increase the efficiency of semiconductor manufacturing. However, the technical challenge of combining both processes in one reactor, due to their different requirements for process conditions and gas flow, has so far prevented their implementation.

[0014] State of the art

[0015] A gas injector for such ALD, PEALD, or ALE process reactors is known from DE 10 2016 108 845 A1. The gas injector is designed as an annular base body, with gas inlet nozzles arranged symmetrically toward the center within the base body. The inlet nozzles are supplied with gas individually or in groups via gas inlets. For this purpose, at least one bypass is provided to deliver the gas uniformly to the inlet nozzles. This brings the reaction area, in which the substrate is arranged, into contact with the reaction partner for the reaction in a uniform manner, both temporally and spatially.

[0016] EP 0552 491 B1 relates to a plasma etching process using high-frequency plasma processing reactors. In particular, a plasma reactor is described that uses a high-frequency (HF) energy source to electromagnetically couple the associated electromagnetic RF wave to the plasma, with a silicon source in contact with the plasma. Processes are carried out in such a reactor.

[0017] DE 10 2020 107 215 A1 describes a method for processing a semiconductor wafer. The method comprises loading a semiconductor wafer onto an upper surface of a wafer chuck. The method further comprises supplying a gaseous material between the semiconductor wafer and the upper surface of the wafer chuck through a first gas inlet opening and a second gas inlet opening arranged below a fan-shaped portion of the upper surface. The method further comprises supplying a fluid medium into a fluid inlet opening of the wafer chuck and guiding the fluid medium from the fluid inlet opening such that it flows through a plurality of arcuate channels arranged below the fan-shaped portion of the upper surface. The method also comprises supplying a plasma gas over the semiconductor wafer.

[0018] DE 10 2019 001 615 A1 presents a plasma-assisted CVD process in which the energy for generating the plasma is not coupled into the CVD reactor through electromagnetic radiation, but rather energy is released through an explosion process, which ultimately generates the plasma. This creates a plasma within the explosion zone with layer-forming and growth-promoting reaction species. These, via the shock front spreading from the explosion site, impinge on the substrate surface, where the thin film to be deposited is formed. The advantage of such a process is film deposition within a very short period of time. However, uniform deposition on a substrate cannot be easily achieved with this process.

[0019] DE 11 2014 005 386 B4 relates to a vapor deposition system designed to perform plasma-activated atomic layer deposition (PEALD) vapor deposition cycles, which can be used to deposit thin-film material layers on exposed surfaces of a solid substrate. The PEALD system includes, in particular, a reaction chamber, a main vacuum pump for establishing a first vacuum pressure in the reaction chamber during non-plasma precursor deposition cycles, and a second vacuum pump for establishing a second, lower vacuum pressure in the reaction chamber during plasma precursor deposition cycles. WO 2007 / 042017 A1 relates to a device and a method for plasma treatment of objects. The device comprises a plasma chamber in which at least one electrode is arranged as an object carrier.Furthermore, at least one wall region of the plasma chamber and / or at least one component arranged in the plasma chamber forms a counterelectrode. A high-frequency unit applies a high-frequency alternating voltage between the electrode and the counterelectrode to generate a plasma in the plasma chamber. The plasma chamber is divided by a separating device into at least two sub-volumes, a first sub-volume for a reactive gas containing the electrode, and a second sub-volume for an inert gas containing a region of the counterelectrode that is active during plasma generation.

[0020] The separation device is designed to enable the electron exchange required for plasma generation between the sub-volumes and to act as a diffusion barrier for the reactive gas. The device and the associated method can reduce deposits on the counter electrode caused by the plasma treatment.

[0021] The known ALD, PEALD, and ALE systems have the disadvantage that the substrates to be treated do not come into uniform contact with their reaction partners via their surfaces. This is caused by an uneven distribution of the reacting gas in the reaction chamber.

[0022] Furthermore, WO 2023 / 147814 A1 discloses a process reactor for plasma etching with atomic precision (ALE) and / or plasma-enhanced deposition (PEALD) of atomic layers on a substrate. It comprises a rotationally symmetric reaction chamber, a centrally positioned table or support for the substrate, a gas supply for uniformly wetting the substrate with gas, a pump for evacuating the chamber, and means for plasma generation. The described embodiment is characterized by the rotationally symmetric arrangement of the reaction chamber and the centrally symmetric positioning of the pump under the table or support. Disclosure of the Invention

[0023] The object of the invention is to avoid the disadvantages of the prior art and to provide a process reactor and a method for an improved and more efficient production of structures on a substrate.

[0024] According to the invention, the object is achieved in that a process reactor for the production of structures on a substrate by means of plasma etching with atomic precision and / or plasma-assisted deposition of atomic layers of the type mentioned above further comprises the following features: e) a first and a second frequency generator for generating high-frequency high voltages; f) a first and a second electrode for generating a high-frequency alternating electric field for the ionization of gas to generate a plasma, wherein the first electrode can be supplied with high voltages of a first frequency by the first frequency generator and with high voltages of a second frequency by the second frequency generator; wherein the second electrode is grounded so that the plasma can be generated in a controlled manner with controllable ion energy.

[0025] A particularly advantageous aspect of the invention lies in the integration of two frequency generators in a process reactor. These frequency generators enable the targeted control and modulation of a generated plasma by using different frequencies for the ionization of gases. Depending on requirements, high voltages with a first frequency or a second frequency can be applied to the first electrode. The proposed process reactor also allows for the addition of a high voltage with a further frequency to an existing high voltage with a specific frequency, so that high voltages of different frequencies are applied simultaneously to the first electrode. This leads to precise control over the ion acceleration, the plasma density, and the electron temperature, which in turn enables efficient, uniform, and controlled deposition or etching at the atomic level on the substrate.Through this targeted manipulation of the plasma, materials with different chemical and physical properties can also be processed efficiently and precisely, which expands the versatility and range of applications of the process reactor.

[0026] The grounded second electrode also contributes to the stabilization of the plasma, which improves process reliability and the quality of the final products.

[0027] Another particularly advantageous aspect of the invention is that the structural design and the possibility of individually adapting the process reactor to different process requirements allow both plasma etching with atomic precision and plasma-assisted deposition of atomic layers to be performed in one and the same process reactor. This enables (automated) sequential processing of a substrate using the aforementioned methods without the need to place the substrate in different process reactors. This is considered a significant departure from the prior art, which previously required different process reactors for plasma etching and plasma-assisted deposition.

[0028] In a preferred embodiment of the process reactor, the first frequency comprises a low frequency and the second frequency a high frequency. The low frequency corresponds to a value selected from the range comprising: 400 kHz to 5 MHz. The low frequency preferably corresponds to a value of 2 MHz. In contrast, the high frequency corresponds to a value selected from the range comprising: 40 MHz to 150 MHz. The high frequency preferably corresponds to a value of 60 MHz. The low frequency serves in particular for ion acceleration, while the high frequency preferably serves for the plasma density and electron temperature. The aforementioned value ranges have proven to be particularly effective. The selection was not made randomly, but rather is based on lengthy research work on the process reactor according to the invention.

[0029] In a further preferred embodiment of the process reactor, the table and / or the holder comprises the first electrode or is configured as such. Furthermore, a chamber wall and / or a lid preferably comprises the second electrode or is configured as such. This configuration advantageously enables efficient use of the spatial arrangement of the process reactor according to the invention; in this respect, the embodiment enables a compact design. Furthermore, the integration of the electrodes into structural components of the reactor, such as the table or the chamber walls, can simplify the design of the reactor and increase its reliability, since fewer separate components are required and the construction becomes more robust overall.

[0030] In the context of the invention, a lid refers to the upper cover of the reaction chamber. In the aforementioned embodiment, the lid can function as a second electrode or contain one, meaning it is directly involved in the generation and control of the plasma within the chamber. The chamber wall refers, in particular, to the lateral boundaries of the reaction chamber of the process reactor. Like the lid, the chamber wall can serve as a second electrode or contain one.

[0031] In a further preferred embodiment, the first and second electrodes are configured as plates arranged essentially parallel to one another. This configuration enables a very uniform distribution of the plasma within the reaction chamber, as the electrode arrangement and design supports a homogeneous electric field distribution. This leads to more even treatment of the substrate, improves the uniformity of the etching or coating, and reduces potential defects or inhomogeneities on the processed substrate. The distance between the plates should be as small as possible, preferably in the range of 1 mm to 10 mm. A distance of 3 mm has proven particularly suitable. This keeps the reaction chamber containing the plasma small, which significantly accelerates the exchange of reaction gases or cleaning gases.

[0032] In a further preferred embodiment, the reaction chamber is rotationally symmetrical or cylindrical, with the lid and the table and / or the holder preferably forming the parallel plates. The rotationally symmetrical or cylindrical design of the reaction chamber enables a uniform distribution of the reaction medium, which leads to homogeneous reaction conditions within the chamber. The interplay of the rotational symmetry of the reaction chamber and the pump arranged centrally therein ensures a uniform flow in the area of ​​the substrate surface during operation of the system. The pump is arranged below the table and / or the holder. In this way, it is possible to ensure a uniform and even flow during evacuation in the reaction chamber.

[0033] In a further preferred embodiment, the process reactor comprises a control unit, wherein the control unit is configured to control and / or regulate the gas supply, the pump, and the frequency generators in such a way that switching from plasma etching with atomic precision to plasma-assisted deposition of atomic layers, and vice versa, can occur without further manual adjustment of the process reactor. The integration of a control unit enables automated process control and adaptation to different process requirements. The ability to switch between plasma etching and plasma-assisted deposition without manual adjustment increases the flexibility and efficiency of the process reactor for different applications.

[0034] In the context of this invention, a control unit is primarily understood as a functional unit that can monitor, regulate, and control the manufacturing process. This unit can be modular in design to allow flexible adaptation to various control tasks. The control unit preferably comprises a data processing unit equipped with a processor, memory, sensors, and / or communication means.

[0035] In a further preferred embodiment, the nozzles enclosed in the conduit ring are designed as Laval nozzles. Configuring the nozzles as Laval nozzles enables efficient gas acceleration, which leads to improved gas dynamics and reaction kinetics in the process. Laval nozzles can also preferably increase the uniformity of the gas flow, which contributes to a more uniform treatment of the substrate surface and thus to higher quality of the final products.

[0036] In a further preferred embodiment, the line ring comprises multiple gas lines. The inclusion of multiple gas lines in the line ring allows for the simultaneous or sequential supply of different gases. Separate gas routing can also contribute to improved control of the gas composition and concentration, which increases the precision of the chemical processes in the reactor. In particular, the gas supply or line ring is designed to introduce process gases such as O2, N2, HBr, Cl, H2, CH4, CHF3, C4F8, C4F6, SFe, and NF3 into the reaction chamber. The process gases can also be introduced into the reaction chamber as diluted gas mixtures.

[0037] The substrate preferably comprises a silicon wafer, a gallium nitride wafer, a quartz wafer, or a gallium arsenide wafer. The gallium nitride wafer and the gallium arsenide wafer are preferably used in combination with aluminum. The use of different substrate types, such as silicon wafers, gallium nitride wafers, quartz wafers, or gallium arsenide wafers, enables broad applicability of the process reactor for different semiconductor materials and thus high flexibility in semiconductor manufacturing.

[0038] In a further preferred embodiment, the table and / or the holder have a constant first temperature. In contrast, a chamber wall and / or the lid have a constant second temperature. The chamber wall preferably has a first temperature of 90°C, while the table preferably has a second temperature within a range of -50°C to 150°C.

[0039] In a further preferred embodiment, the invention relates to a method for producing structures on a substrate in a process reactor according to one of the preceding embodiments, wherein the method comprises the following steps: a) introducing a substrate into a reaction chamber of the process reactor; and b) carrying out plasma etching with atomic precision on the substrate in the reaction chamber; or c) carrying out plasma-assisted deposition of atomic layers on the substrate in the reaction chamber; or d) successively carrying out plasma etching with atomic precision and plasma-assisted deposition of atomic layers on the substrate in the reaction chamber, wherein the order of the successively carried out

[0040] Processes can vary and the change from plasma etching with atomic precision to plasma-assisted deposition of atomic layers, and vice versa, takes place without further manual adjustment of the process reactor.

[0041] The ability to perform atomic-precision plasma etching and plasma-assisted atomic layer deposition, either separately or in sequential steps, in a single process reactor provides high process flexibility and enables the production of complex structures with precise layer thicknesses. Automated switching between plasma etching and deposition without manual adjustments reduces process time and minimizes the risk of contamination or errors, resulting in higher yield and cost efficiency.

[0042] A person skilled in the art will recognize that the advantages, technical effects, and preferred embodiments discussed in connection with the process reactor according to the invention apply analogously to the method according to the invention for producing structures on a substrate. Likewise, all advantages, technical effects, and preferred embodiments described in the context of the method are transferable to the process reactor.

[0043] In a further preferred embodiment, the method is characterized in that, during the plasma etching with atomic precision and the plasma-assisted deposition of atomic layers, at least one gas is introduced into the reaction chamber via a gas supply, wherein the gas supply consists of a gas injector comprising a conduit ring with nozzles. The use of a gas injector with a conduit ring and nozzles enables a uniform and even distribution of the gases in the reaction chamber, resulting in a homogeneous reaction environment and thus in more uniform etching and deposition processes. The precise gas supply through the gas injector can further improve the efficiency of material consumption and reduce process costs by minimizing gas consumption and increasing process reliability. Furthermore, a second process chamber (either ALD or ALE) can be eliminated.This offers advantages, particularly with regard to energy costs and sustainability.

[0044] In a further preferred embodiment, during the plasma etching with atomic precision and the plasma-assisted deposition of atomic layers, a plasma is ignited via an alternating electric field generated by two electrodes contained in the process reactor, wherein a first electrode is supplied with high voltages of a first frequency by a first frequency generator and with high voltages of a second frequency by a second frequency generator; wherein the second electrode is grounded.

[0045] As already discussed in the context of the process reactor according to the invention, the use of two different frequencies enables differentiated control of the plasma properties, thus achieving more precise adaptation to the specific requirements of the etching or deposition process. In particular, it enables very precise control of the ion energy for the kinetic reaction, independent of plasma density and average electron temperature.

[0046] In a further preferred embodiment, plasma etching is carried out with atomic precision in such a way that the substrate is uniformly wetted with an etching gas via the gas supply, wherein the substrate to be processed is arranged centrally in the conducting ring; an inert gas is introduced into the reaction chamber via the gas supply in order to purge excess etching gas and clean the reaction chamber; a high-frequency alternating electric field is provided to generate a plasma; the reaction chamber is evacuated via a pump.

[0047] The consistent and, if possible, uniform wetting of the substrate with etching gas results in a homogeneous etching rate across the entire substrate surface, which improves the uniformity and quality of the processed structures. The etching gas can be used either in pure form or as a gas mixture. The introduction of an inert gas to purge excess etching gas and clean the reaction chamber minimizes contamination and defects on the substrate. Evacuating the reaction chamber using a pump creates a controlled pressure environment and ensures low pressure throughout the entire process. This increases process stability and reproducibility and maintains a stable plasma.

[0048] In a further preferred embodiment, the plasma-assisted deposition of atomic layers is carried out in such a way that the substrate is uniformly wetted with a gas mixture, which proportionally comprises a precursor gas, via the gas supply, wherein the substrate to be processed is arranged centrally in the conduction ring; a high-frequency alternating electric field is provided to generate a plasma; a reaction gas, such as O2, H2, N2, HCl, Cl2, HBr, NF3, SFe, CF4, C4F6, C4F8, CHF3, CH4, is introduced into the reaction chamber via the gas supply; an inert gas is introduced into the reaction chamber via the gas supply in order to flush out excess precursor gas and / or all reaction products and unwanted gases and to clean the reaction chamber; the reaction chamber is evacuated via a pump.

[0049] The uniform wetting of the substrate with a gas mixture containing a precursor gas enables, in particular, the homogeneous deposition of material layers, resulting in improved layer quality and uniform layer thicknesses. Evacuating the reaction chamber via a pump and purging it with an inert gas results in an effect already described in the course of plasma etching. It is understood that the reaction gases can also be introduced into the reaction chamber in a diluted form as a gas mixture. The precursor gas, on the other hand, can also be introduced into the reaction chamber as a pure gas to wet the substrate.

[0050] In a further preferred embodiment, the following process step is interposed between plasma etching with atomic precision and the plasma-assisted deposition of atomic layers: an inert gas is introduced through a gas supply. The interposition of an inert gas after plasma etching (or after deposition) and before the deposition of atomic layers (or before plasma etching) prevents unwanted chemical reactions and contamination. The introduction of an inert gas contributes to stabilizing the reaction conditions by serving as a buffer between the individual process steps, thus improving process control.

[0051] In a further preferred embodiment, the individual process steps of plasma etching with atomic precision and plasma-assisted deposition of atomic layers are automated via a control unit, wherein the control unit is based on artificial intelligence algorithms. The implementation of artificial intelligence algorithms in the control system enables adaptive process control that can adapt to changing operating conditions in real time, leading to increased efficiency and precision of the process. By utilizing artificial intelligence, the process can integrate self-learning mechanisms that enable continuous optimization of process parameters, thereby improving product quality and reducing scrap rates.

[0052] Further embodiments and advantages emerge from the subject matter of the dependent claims and the drawings with the associated descriptions. Exemplary embodiments are explained in more detail below with reference to the attached drawings. In addition, spatially relative terms such as "beneath", "under", "lower", "above", "upper" and the like may be used in the present text to simplify the description and to describe the relationship of one element or structural element to one or more other elements or structural elements, as illustrated in the figures. The spatially relative terms are intended to include, in addition to the orientation shown in the figures, other orientations of the device during use or operation.The device may also be oriented differently (rotated 90 degrees or oriented differently), and the spatially relative descriptors used in this text may equally be interpreted accordingly.

[0053] The invention is not intended to be limited solely to these exemplary embodiments. They serve merely to explain the invention in more detail. The present invention is intended to relate to all subject matter that a person skilled in the art would consider obvious for implementing the invention, now and in the future. Furthermore, the content of the cited publications is incorporated into the disclosure of the present application.

[0054] Short description of the drawing

[0055] Fig. 1 shows a schematic diagram of a vertical section through a preferred embodiment of the process reactor according to the invention

[0056] Fig. 2 shows a schematic diagram of a horizontal section through a preferred embodiment of the process reactor according to the invention

[0057] Fig. 3 shows a flow chart of a preferred embodiment of the method according to the invention

[0058] Fig. 4 shows a flow chart of a preferred embodiment of the

[0059] Plasma etching with atomic precision

[0060] Fig. 5 shows a flow diagram of a preferred embodiment of the plasma-assisted deposition of atomic layers

[0061] Preferred embodiment

[0062] Fig. 1 shows a schematic diagram of the vertical section of a process reactor 10 according to the invention for plasma etching with atomic precision of a substrate 12 and / or for plasma-assisted deposition of atomic layers on the substrate 12. In this exemplary embodiment, the process reactor 10 contains a protective housing 14 in which a reaction chamber 16 is provided. While the protective housing 14 can have almost any geometric shape as a housing body, the reaction chamber 16 is designed to be rotationally symmetrical.

[0063] In the present embodiment, reaction chamber 16 is essentially cylindrical. In principle, other rotationally symmetrical geometries of the reaction chamber 16 are also conceivable, such as a conical or spherical reaction chamber 16. The substrate 12 is held centrally on a table 18 within the reaction chamber 16. The table 18 is supported by six tubular profile bodies 20.

[0064] The tubular profile bodies 20 are hollow at their core, creating a cavity 22 within them. Supply and control lines 21, both supply lines 24 and discharge lines 26, are routed from the reaction chamber 16 through the cavity 22 of the tubular profile bodies 20. The supply lines 24 and discharge lines 26 are, for example, required electrical lines, liquid or gas lines. These supply lines 21 are routed through passages 27 in the table 18. In this way, resources can be supplied centrally and symmetrically to the substrate 12 from outside the reaction chamber 16. The tubular profile bodies 20 are designed to be height-adjustable. This is achieved by a telescopic structure of the tubular profile bodies 20, which can change their length via a drive 28.

[0065] The substrate 12 is introduced into the reaction chamber 16 for processing via a vacuum lock 29, and is centrally positioned and fixed on the table 18 – also called a "chuck." The finished substrate 12 is also removed from the reaction chamber 16 through the vacuum lock 29.

[0066] In the reaction chamber 16 of the process reactor 10, a gas supply 31 is provided in the upper region 30. The gas supply 31 is designed as a gas injector 32. From outside the reaction chamber 16, a gas or a gas mixture is fed to the gas injector 32 through a gas line 33. The gas injector 32 consists of a line ring 34 on which numerous Laval nozzles 36 are arranged. The center of the ring-shaped gas injector 32 lies on a central axis 38 of the reaction chamber 16. The Laval nozzles 36 are arranged radially symmetrically around the central axis 38. In this exemplary embodiment, the Laval nozzles 36 point towards the central axis 38 of the reaction chamber 16. To create a uniform and symmetrical distribution of the reaction gas at the Laval nozzles 36, at least one channel is provided as a bypass 40 to the line ring 34.

[0067] Connections 42, 44 serve to connect the gas line 33, such as for helium, and electrical supply and control lines 21 to the process reactor 10. The amount of gas supplied to the gas injector 32 can be regulated via an adjustable control valve 45. In addition, the process reactor has a first and a second electrode 46, 47 for generating a high-frequency alternating electric field for the ionization of gas to generate a plasma. The reactivity of the reactants with the substrate 12 is significantly increased when a plasma is used. The plasma is created by igniting a gas discharge. Argon is a particularly suitable plasma gas for the reaction processes. A sequential sequence is achieved by pulsing the plasma power.

[0068] The second electrode 47 is grounded. The first electrode 46, in contrast, is supplied with high-frequency high voltage, in particular via terminal 55 and electrical supply lines 24. In this context, a first and a second frequency generator 64, 66 are provided for generating high-frequency high voltages, wherein the first electrode 46 can be supplied with high voltages of a first frequency by the first frequency generator 64 and with high voltages of a second frequency by the second frequency generator 66.

[0069] It is preferably provided that high voltages of the second frequency can be added to the high voltages of the first frequency applied to the first electrode 46, and vice versa, so that high voltages of the first and second frequencies are applied to the first electrode 46 simultaneously.

[0070] The proposed process reactor 10 is characterized, among other things, by the fact that the first frequency comprises a low frequency and the second frequency a high frequency. The low frequency can correspond to a value in the range of 400 kHz to 5 MHz, while the high frequency can correspond to a value in the range of 40 MHz to 150 MHz.

[0071] The table 18 comprises the first electrode 46 or can be configured as such. The cover 68 of the process reactor 10, however, has the second electrode 47.

[0072] Furthermore, the process reactor 10 has a control unit 62. The control unit 62 can be divided into individual, separate, processor-controlled modules that perform different tasks. The control unit 62 is particularly configured to control and / or regulate the gas supply 31, the pump 60, and the frequency generators 64, 66 in such a way that switching from plasma etching with atomic precision to plasma-assisted deposition of atomic layers, and vice versa, can occur without further manual adjustment of the process reactor 10.

[0073] An annular dynamic pressure generator 48 is provided in the lower region 50, below the table 18. The dynamic pressure generator 48 is an annular screen 54, which is a grounded metal ring with numerous narrow-mesh holes 52 through which a gas can be evacuated. The dynamic pressure generator 48 serves as a dynamic pressure generator for the gas in the reaction chamber 16 and simultaneously limits the expansion of the plasma generated in the reaction chamber 16. The dynamic pressure generator 48 thus also acts as a plasma limiter. The dynamic pressure generator 48 also largely decouples the flow of the lower region 50 from the upper region 30.

[0074] The reaction chamber 16 has a central opening 58 at its bottom 56. A turbopump 60 is flanged centrally symmetrically to this central opening 58. The output of the turbopump 60 is regulated by a processor-controlled control unit 62. The turbopump 60 serves to evacuate the reaction chamber 16. The turbopump 60 ensures that the reaction chamber 16 operates permanently in the low-pressure range.

[0075] The rotationally symmetric reaction chamber 16 and the correspondingly symmetrical arrangements of the components for the gas supply and the evacuation of the gas as a reaction partner for the substrate 12 allow for an extremely uniform flow distribution in the region of the centrally symmetrically arranged substrate 12. This desired uniform distribution results in an equally uniform reaction of the gas as a reaction partner with the substrate 12.

[0076] Fig. 2 shows a schematic diagram of a horizontal section through the process reactor 10 according to the invention shown in Fig. 1. Where the components of the two figures correspond, the same reference numerals are used. As is clearly evident in this illustration of Fig. 2, the components are arranged rotationally symmetrically around the central axis 38. The reaction chamber 16 is provided in the protective housing 14.

[0077] In the reaction chamber 16, the gas injector 32 is arranged centered around the axis 38. Laval nozzles 36 are provided on the line ring 34. Some of the Laval nozzles 36 are supplied with gas from the line ring 34 and the other from the bypass 40. In the present embodiment, the gas injector 32 is supplied with a gas or gas mixture as a reactant from the single gas supply line 33, which is connected to the gas connection 42. The amount of gas supplied to the gas injector 32 via the gas connection 42 is regulated by the control valve 45.

[0078] The table 18, on which the substrate 12 is fixed, is supported by the six tubular profile bodies 20. Both the table 18 or chuck and the substrate 12 are positioned centrally in the reaction chamber 16 below the gas injector 32. The profile bodies 20 are also arranged radially symmetrically around the axis 38.

[0079] The supply lines 24 and, if applicable, also the outlet lines 26 are routed through the profile bodies 20. The supply lines 24 are gas lines through which, for example, the gas helium is transported, or electrical lines through which the first electrode 46 is supplied with high voltage. These lines are sufficiently insulated, if necessary, to prevent electrical arcing caused by the high voltage. Heating elements (not shown) are also supplied with voltage via such supply lines 24. The outlet lines 26 can be, for example, signal lines through which signals from sensors (not shown) or control signals for various components are transmitted.

[0080] This horizontal sectional view clearly shows the mesh-like structure of the dynamic pressure generator 48. The dynamic pressure generator 48 is formed by the grounded metallic annular screen 54 with its holes 52. The dynamic pressure generator 48 also prevents unwanted expansion of the plasma. The dynamic pressure generated by the dynamic pressure generator 48 for a gas or gas mixture to be evacuated optimizes the uniformity of the flow in the upper region 30. The flow behavior below the dynamic pressure generator 48 is largely negligible for the reaction of the substrate 12 with a gas as a reactant.

[0081] The turbopump 60 evacuates the reaction chamber 16. Due to the centrally symmetrical arrangement of the turbopump 60 at the bottom 56 of the reaction chamber 16, the gas or gas mixture is sucked symmetrically through the central opening 58 into the turbopump 60. The radially symmetrical flow paths of the gas or gas mixture are all approximately the same, thereby essentially ensuring optimized uniformity of the flow paths in the region of the substrate 12. The symmetrical flow paths are achieved only by the radially symmetrical arrangements of the components, as well as the rotationally symmetrical reaction chamber 16 and the centrally symmetrically mounted turbopump 60.

[0082] Fig. 3 shows a flow diagram of a preferred embodiment of the method according to the invention for producing structures on a substrate 12 in a process reactor 10, which comprises the following steps:

[0083] A substrate 12 is introduced into a reaction chamber 16 of the process reactor 10. The substrate 12 can then either be subjected to a plasma etching process with atomic precision, or a plasma-assisted deposition of atomic layers onto the substrate 12 can be performed. It is also possible to perform these two processes sequentially, although the order of the processes can vary. Between the plasma etching and the deposition of atomic layers, inert gas is introduced via a gas supply to clean the reaction chamber 16.

[0084] The change between plasma etching and plasma-assisted deposition of atomic layers is automated without further manual adjustment of the process reactor 10.

[0085] Fig. 4 shows a flow diagram of a preferred embodiment of plasma etching with atomic precision. In a first step, a substrate 12 is introduced into the reaction chamber 16 of the process reactor 10. Subsequently, the substrate 12 is evenly wetted with an etching gas via a gas supply 31. The substrate 12 to be processed is positioned centrally in the conduction ring 34.

[0086] An inert gas is introduced into the reaction chamber 16 via the gas supply 31, particularly to flush out excess etching gas and clean the reaction chamber 16. The inert gas is continuously introduced into the reaction chamber 16. In addition, a high-frequency alternating electric field is provided to generate a plasma. Furthermore, the reaction chamber 16 is continuously evacuated by means of a pump 60.

[0087] Fig. 5 shows a flow diagram of a preferred embodiment of plasma-assisted atomic layer deposition. In a first step, a substrate 12 is introduced into the reaction chamber 16 of the process reactor 10. Subsequently, the substrate 12 is uniformly wetted with a gas mixture that partially contains a precursor gas. This occurs via a gas supply 31, and the substrate 12 to be processed is positioned centrally in the conduit ring 34.

[0088] A high-frequency alternating electric field is provided to generate a plasma. A reaction gas, such as O2 or H2, is introduced into the reaction chamber 16, also via the gas supply 31. An inert gas is continuously supplied to flush out excess precursor gas and / or any reaction products and unwanted gases, and to clean the reaction chamber 16. Furthermore, the reaction chamber 16 is continuously evacuated by means of a pump 60.

[0089] Fig. 6 shows a schematic representation of the coupling of the high-frequency voltages. A multi-frequency tuning device 70 is connected to a first frequency generator 64 and a second frequency generator 66. The first frequency generator 64 is configured to generate high voltages at a high frequency, preferably 60 MHz, while the second frequency generator 66 is set to a lower frequency, preferably 2 MHz. These frequency generators serve to generate a high-frequency alternating electric field required for the ionization of gas and the generation of plasma within a reaction chamber (not shown).

[0090] The multi-frequency tuning device 70 is connected to the first electrode 64 via a high-frequency supply line 72. This is enclosed in the table 18, or the table 18 is configured as such. The first electrode 64 can be selectively subjected to high voltages of the first or second frequency, or a combination of both, in order to precisely control the properties of the plasma and achieve a controllable ion energy.

[0091] List of reference symbols

[0092] 10 Process reactor 55 connection

[0093] 12 Substrate 56 Soil

[0094] 14 protective housing 58 central opening

[0095] 16 reaction chamber 60 pump / turbo pump

[0096] 18 Table 62 Control unit

[0097] 20 tubular profile body 64 first frequency generator

[0098] 21 supply and control lines 66 second frequency generator

[0099] 22 cavity 68 lid

[0100] Multifrequency

[0101] 24 supply lines 70

[0102] Tuning device

[0103] 26 leads 72 high frequency feed

[0104] 27 passages

[0105] 28 Drive

[0106] 29 Vacuum lock

[0107] 30 upper area

[0108] 31 Gas supply

[0109] 32 Gas injector

[0110] 33 Gas pipeline

[0111] 34 cable ring

[0112] 36 Laval nozzles

[0113] 38 Central Axis

[0114] 40 bypass channel

[0115] 42 Gas connection

[0116] 44 connection

[0117] 45 adjustable control valve

[0118] 46 first electrode

[0119] 47 second electrode

[0120] 48 dynamic pressure generators

[0121] 50 lower area

[0122] 52 holes

[0123] 54 Ringsieb

Claims

Patent claims 1. A process reactor (10) for producing structures on a substrate (12) by means of plasma etching with atomic precision and / or plasma-assisted deposition of atomic layers, comprising: a) a reaction chamber (16); b) a table (18) and / or a holder for the substrate (12) in the reaction chamber (16); c) a gas supply (31) which can evenly wet the substrate (12) with gas in the reaction chamber (16), wherein the gas supply (31) consists of a gas injector (32) which comprises a conduit ring (34) with nozzles in which the substrate (12) to be processed can be centrally arranged; d) a pump (60) for evacuating the reaction chamber (16); characterized in that the process reactor (10) further comprises the following features: e) a first and a second frequency generator (64, 66) for generating high-frequency high voltages;f) a first and a second electrode (46, 47) for generating a high-frequency alternating electric field for the ionization of gas to generate a plasma, wherein the first electrode (46) can be supplied with high voltages of a first frequency by the first frequency generator (64) and with high voltages of a second frequency by the second frequency generator (66); wherein the second electrode (47) is grounded so that the plasma can be generated in a controlled manner with controllable ion energy.

2. Process reactor (10) according to claim 1, characterized in that high voltages of the second frequency can be added to the high voltages of the first frequency applied to the first electrode (46), and vice versa, so that high voltages of the first and second frequencies are applied to the first electrode (46) simultaneously.

3. Process reactor (10) according to one of the two preceding claims 1 or 2, characterized in that the first frequency comprises a low frequency and the second frequency comprises a high frequency, wherein the low frequency corresponds to a value selected from the range comprising: 400 kHz to 5 MHz; preferably the low frequency corresponds to a value of 2 MHz; wherein the high frequency corresponds to a value selected from the range comprising: 40 MHz to 150 MHz; preferably the high frequency corresponds to a value of 60 MHz.

4. Process reactor (10) according to one of the preceding claims 1-3, characterized in that the table (18) and / or the holder comprises the first electrode (46) or is designed as such; and a chamber wall and / or a lid (68) comprises the second electrode (47) or is designed as such.

5. Process reactor (10) according to one of the preceding claims 1 - 4, characterized in that the first and second electrodes (46, 47) are designed in the form of plates lying substantially parallel to one another.

6. Process reactor (10) according to claim 4 or 5, characterized in that the reaction chamber (16) is rotationally symmetrical or cylindrical, wherein the cover (68) and the table (18) and / or the holder form the plates lying parallel to one another.

7. Process reactor (10) according to one of the preceding claims 1 - 6, characterized in that the pump (60) is arranged centrally symmetrically below the table (18) and / or the holder on the reaction chamber (16).

8. Process reactor (10) according to one of the preceding claims 1 - 7, characterized in that the process reactor (10) comprises a control unit (62), wherein the control unit (62) is designed to control and / or regulate the gas supply (31), the pump (60) and the frequency generators (64, 66) in such a way that switching from plasma etching with atomic precision to plasma-assisted deposition of atomic layers, and vice versa, can take place without further manual adjustment of the process reactor (10).

9. Process reactor (10) according to one of the preceding claims 1 - 8, characterized in that the nozzles enclosed in the line ring (34) are designed as Laval nozzles (36).

10. Process reactor (10) according to one of the preceding claims 1 - 9, characterized in that Pipe ring (34) comprises several gas pipes.

11. Process reactor (10) according to one of the preceding claims 1 - 10, characterized in that the substrate (12) comprises a silicon wafer, a gallium nitride wafer, a quartz wafer or a gallium arsenide wafer, wherein the gallium nitride wafer and the gallium arsenide wafer are preferably used in combination with aluminum.

12. Process reactor (10) according to one of the preceding claims 1 - 11, characterized in that the gas supply (31) is designed to introduce process gases, such as O2, N2, HBr, Cl, H2, CH4, CHF3, C4F8, C4F6, SFe, NF3, into the reaction chamber (16).

13. Process reactor (10) according to one of the preceding claims 1 - 12, characterized in that the table (18) and / or the holder has a constant first temperature and a chamber wall and / or a lid (68) has a constant second temperature.

14. A method for producing structures on a substrate (12) in a process reactor (10) according to one of the preceding claims, wherein the method comprises the following steps: a) introducing a substrate (12) into a reaction chamber (16) of the process reactor (10); and b) Performing plasma etching with atomic precision on the substrate (12) in the reaction chamber (16); or c) performing plasma-assisted deposition of atomic layers on the substrate (12) in the reaction chamber (16); or d) successively performing plasma etching with atomic precision and plasma-assisted deposition of atomic layers on the substrate (12) in the reaction chamber (16), wherein the order of the successively performed processes can vary and the change from plasma etching with atomic precision to plasma-assisted deposition of atomic layers, and vice versa, takes place without further manual adjustment of the process reactor (10).

15. The method according to claim 14, characterized in that in the course of the plasma etching with atomic precision and the plasma-assisted deposition of atomic layers, at least one gas is introduced into the reaction chamber via a gas supply, wherein the gas supply consists of a gas injector comprising a conducting ring with nozzles.

16. Method according to one of the preceding claims 14 - 15, characterized in that in the course of the plasma etching with atomic precision and the plasma-assisted deposition of atomic layers, a plasma is ignited via an alternating electric field which is generated by two electrodes (46, 47) included in the process reactor (10), wherein a first electrode (46) is supplied with high voltages of a first frequency by a first frequency generator (64) and with high voltages of a second frequency by a second frequency generator (66); wherein the second electrode (47) is grounded.

17. The method according to claim 16, characterized in that high voltages of the second frequency are added to the high voltages of the first frequency applied to the first electrode (46), or high voltages of the first frequency are added to the high voltages of the second frequency applied to the first electrode (46), so that high voltages of the first and second frequencies are applied to the first electrode (46) simultaneously.

18. Method according to one of the preceding claims 16 - 17, characterized in that the first frequency comprises a low frequency and the second frequency comprises a high frequency, wherein the low frequency corresponds to a value selected from the range comprising: 400 kHz to 5 MHz; preferably the low frequency corresponds to a value of 2 MHz; wherein the high frequency corresponds to a value selected from the range comprising: 40 MHz to 150 MHz; preferably the high frequency corresponds to a value of 60 MHz.

19. Method according to claim 18, characterized in that the low frequency serves for ion acceleration and the high frequency for plasma density and electron temperature.

20. Method according to one of the preceding claims 14 - 19, characterized in that the plasma etching is carried out with atomic precision in such a way that the substrate (12) is uniformly wetted with an etching gas via the gas supply (31), wherein the substrate (12) to be processed is arranged centrally in the conducting ring (34); an inert gas is introduced into the reaction chamber (16) via the gas supply (31) in order to purge excess etching gas and to clean the reaction chamber (16); a high-frequency alternating electric field is provided to generate a plasma; the reaction chamber (16) is evacuated via a pump (60).

21. Method according to one of the preceding claims 14-19, characterized in that the plasma-assisted deposition of atomic layers is carried out in such a way that the substrate (12) is uniformly wetted with a gas mixture, which partially comprises a precursor gas, via the gas supply (31), wherein the substrate (12) to be processed is arranged centrally in the conduction ring (34); a high-frequency alternating electric field is provided to generate a plasma; a reaction gas, such as O2, H2, N2, HCl, Cl2, HBr, NF3, SFe, CF4, C4F6, C4F8, CHF3, CH4, is introduced into the reaction chamber (16) via the gas supply (31); an inert gas is introduced into the reaction chamber (16) via the gas supply (31) in order to flush out excess precursor gas and / or all reaction products and unwanted gases and to clean the reaction chamber (16); the reaction chamber (16) is evacuated via a pump (60).

22. Method according to one of the preceding claims 14 - 21, characterized in that the plasma etching with atomic precision and the plasma-assisted deposition of atomic layers are interposed by the following method step: an inert gas is introduced by a gas supply.

23. Method according to one of the preceding claims 14 - 22, characterized in that the substrate (12) comprises a silicon wafer, a gallium nitride wafer, a quartz wafer or a gallium arsenide wafer, wherein the gallium nitride wafer and the gallium arsenide wafer are preferably used in combination with aluminum.

24. Method according to one of the preceding claims 14 - 23, characterized in that the table (18) and / or the holder is tempered to a constant first temperature and a chamber wall to a constant second temperature.

25. Method according to one of the preceding claims 14 - 24, characterized in that the individual method steps of plasma etching with atomic precision and plasma-assisted deposition of atomic layers are carried out automatically via a control unit (629).

26. Method according to claim 25, characterized in that the control is based on artificial intelligence algorithms.

27. Use of the process reactor (10) according to one of the preceding claims 1 - 13 for the production of structures on a substrate (12).

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