Plasma electrode that can be moved within a process chamber of a CVD reactor

Abstract

The invention relates to a device for depositing a layer on a substrate (1) in a process chamber (4) arranged in a housing of a CVD reactor (3), with a gas inlet element (5) for introducing gases into the process chamber (4), with a gas outlet surface (8) having a plurality of gas outlet openings (6, 7) through which the gases can flow into the process chamber (4), with at least one plasma electrode (10) that can be supplied with an electrical voltage by a plasma generator (9) and is configured to supply energy to a gaseous starting material in order to generate a plasma, wherein the plasma electrode (10) is arranged to be displaceable in the process chamber (4).

Description

field of technology

[0001] The invention relates to a device for depositing a layer on a substrate in a process chamber arranged in a housing of a CVD reactor, with a gas inlet device for introducing gases into the process chamber, with a gas outlet surface having a plurality of gas outlet openings through which the gases can flow into the process chamber, with at least one plasma electrode that can be supplied with an electrical voltage by a plasma generator and which is configured to supply energy to a gaseous starting material in order to generate a plasma. State of the art

[0002] During the deposition of layers onto substrates in a CVD reactor process chamber, process gases introduced into the chamber via a gas inlet are decomposed pyrolytically or catalytically. The resulting decomposition products crystallize not only on the substrates but also on other surfaces within the process chamber exposed to the process gases. This undesirable parasitic growth generates impurities that contaminate substrates stored in the process chamber during subsequent processes. This reduces the efficiency and reproducibility of these subsequent processes and impairs the growth behavior of the layer being deposited on the substrates.

[0003] To remove such parasitic deposits from the surfaces of the process chamber, cleaning processes are typically carried out within the chamber. These processes involve the introduction of cleaning gases such as Cl₂, HCl, NH₃, H₂, or O₂. For these gases to form the radicals necessary for surface cleaning, comparatively high cleaning temperatures of several hundred degrees Celsius are required within the process chamber for an extended period. Particularly in a CVD reactor, where the walls or ceiling of the process chamber are directly cooled, a high heat output is required to raise the surface temperature of the process chamber, heated by the susceptor through thermal radiation, to the desired cleaning temperature. This results in high energy consumption for the heating equipment required to heat the susceptor.On the other hand, long cleaning processes in practice lead to considerable downtimes during which the CVD reactor is unproductive, meaning no growth processes can be carried out in the process chamber, thus significantly reducing the overall productivity of the CVD reactor.

[0004] EP 2 876 083 B1 discloses a device with a gas inlet element through which various gases can be fed into a process chamber. A plasma electrode, which can be subjected to an electrical voltage, is arranged in the gas inlet element and can be used to ignite a plasma in order to associate or dissociate gaseous starting materials. These gaseous starting materials can be precursor organases used in growth processes or cleaning gases used for cleaning a process chamber. The cleaning gases can be converted into cleaning radicals by means of the plasma to remove deposits from surfaces within the process chamber. The plasma electrode can be a plate forming a plurality of openings, arranged within the gas inlet element between two grounded shield electrodes, also designed as plates.

[0005] US Patent 2002 / 012976 A1 describes a CVD reactor with a showerhead gas inlet through which various process gases are fed into a process chamber. To convert the process gases into radicals, a plate-shaped plasma electrode is provided within the gas inlet above the gas outlet plate, through which the gases flow into the process chamber. To ignite a plasma within the gas inlet, the plate is energized by a voltage source located outside the reactor housing. The plate is contacted by means of an RF rod passing through the housing roof. The gas outlet plate is grounded by contact with the housing roof and acts as the counter electrode.

[0006] US Patent 2010 / 0072054 A1 discloses a CVD reactor with a showerhead-type gas inlet for introducing various gases into a process chamber of the CVD reactor. The gas inlet has a gas outlet plate facing the process chamber, which features a plurality of gas outlet openings through which the gases can flow into the process chamber. The gas outlet plate acts as a plasma electrode, which can be energized by a voltage source located outside the process chamber. A grounded plate located below the gas outlet plate acts as a counter electrode. The plasma is thus generated between the gas outlet plate and the counter electrode.To prevent the released ions and electrons from entering the process chamber, several vertically stacked shielding plates are arranged between the counter electrode and the susceptor, each of which also has numerous gas outlet openings. The shielding plates adsorb the ions and reflect the electrons.

[0007] From DE 10 2011 056 589 A1, a CVD reactor with a gas inlet device designed as a showerhead is known, through which various gases can be fed into a process chamber bounded at the bottom by a heated susceptor. A thermally decoupled shielding plate is provided with respect to a cooled gas outlet surface of the gas inlet device. This shielding plate is spaced from the cooled gas outlet surface of the showerhead by a gap and is heated by conduction or radiation from the susceptor. The shielding plate forms a plurality of gas outlet openings through which the gases can be fed into the process chamber. The shielding plate is arranged in the reactor housing in a height-adjustable manner relative to the showerhead and the susceptor.

[0008] Li et al. (Li, S., Tompa, GS, Moy, K. et al. In-situ plasma cleaning of stainless steel III-V MOCVD growth systems. J. Electron. Mater. 21, 149-156 (1992). https: / / doi.org / 10.1007 / BF02655830) disclose a device and a method for cleaning a process chamber of a MOCVD reactor using a plasma. A susceptor is arranged within the process chamber and is heated by a heating device located below the susceptor. Three electrodes are provided for generating the plasma: a first electrode is located above the susceptor, a second electrode below the heating device, and a third electrode at the bottom of the process chamber. Ar, CH4 (5% in H2), H2, CCl2F2, and Cl2 are introduced into the process chamber as cleaning gases, either individually or in combination. In addition, the plasma was used to etch III-V layers, such as GaAs and InP, onto substrates located on the susceptor. Summary of the invention

[0009] The invention is based on the objective of taking measures to reduce the heat power applied to heating a process chamber of a CVD reactor and / or to selectively remove residues from the surfaces in the process chamber or from objects arranged in the process chamber, as well as a method.

[0010] The problem is solved by the device or method specified in the claims. The dependent claims not only represent advantageous further developments of the technical teachings specified in the dependent claims, but are also independent solutions to the problem.

[0011] The invention essentially provides a plasma electrode arranged within the process chamber of a CVD reactor and capable of being moved. This electrode can be subjected to an electrical voltage by a plasma generator to generate a plasma. The plasma electrode can be positioned anywhere within the process chamber and moved vertically and / or horizontally. Preferably, the plasma electrode is a plate extending horizontally or vertically. Several such movable plasma electrodes can also be provided in a single process chamber. The plasma electrode can preferably be thermally and electrically decoupled from other components arranged within the process chamber or moved from a position of contact with grounded parts of the process chamber to a position at a distance that is electrically isolated from them.One or more counter electrodes, particularly grounded ones, can be provided, formed by other components arranged in the process chamber. For example, the counter electrode can be a wall of the housing surrounding the process chamber, and / or a bottom of the process chamber, and / or a gas inlet through which various gases can be introduced into the process chamber, and / or the susceptor. When a voltage is applied to the plasma electrode, the plasma initially forms between the plasma electrode and the nearest counter electrode, i.e., the counter electrode with the smallest vertical or horizontal distance to the plasma electrode. By increasing the voltage or power applied to the plasma electrode, the extent of plasma propagation within the process chamber can be controlled.The voltage can be adjusted so that the plasma extends beyond the volume formed between the nearest electrodes, covering the entire plasma electrode and the process chamber. The plasma can be excited, for example, by an alternating current (AC) or a direct current (DC). The frequency of the AC voltage can be in the range of Hz, kHz, MHz, or GHz, depending on the plasma power supply used. Plasma excitation can also be achieved with a pulsed waveform, which can be negative or positive (reverse polarity) or include discharge pauses, with the pulsed waveform being repeated at a frequency in the Hz, kHz, or MHz range. Alternatively, the plasma can be excited by a combination of the aforementioned waveforms, for example, by pulsed alternating current.

[0012] In a first embodiment of the invention, the plasma electrode can be configured as a plate or grid arrangement positioned between the gas inlet element and the susceptor. The plate preferably extends over the entire cross-sectional area of ​​the gas inlet element. However, the plate can also extend over only a portion of the cross-sectional area of ​​the gas inlet element. The gas inlet element can be configured as a showerhead, which has a cooled gas outlet surface facing the process chamber with a plurality of gas outlet openings through which gases can be fed into the process chamber. For example, the gas inlet element can be a showerhead and the plasma electrode a shielding plate, as disclosed in DE 10 2021 114 868 A1.

[0013] The plasma electrode, for example the plate, can be electrically connected to the plasma generator, located either outside or inside the reactor housing, by means of a suitable contact element. The contact element can be, for example, an extendable rod, a cable, a folding contact, or a spring. The contact element can, for example, pass through an electrically insulated opening in the reactor housing. The contact element can also pass through the gas inlet, for example, through a channel opening into the gas outlet. The contact element can also be part of a lifting element that allows the plate to be moved within the process chamber. The plate can also be electrically connected to the plasma generator in other ways.

[0014] The plasma electrode can initially be positioned in close proximity to, in particular at a distance of less than 1 mm or in contact with, the cooled gas inlet housing wall, and then moved downwards away from the cooled gas outlet surface of the gas inlet element into a spaced position to thermally and electrically decouple the plasma electrode from the cooled gas inlet housing wall of the gas inlet element. In the spaced position, the plasma electrode can be separated from the gas outlet surface of the gas inlet element by a clearance gap. In the spaced position, the plasma electrode can, in particular, be positioned at a distance of more than 1 mm from the gas outlet surface. In the contact position, the plasma electrode can be in contact with the gas outlet surface, at least partially, or, in particular, be positioned at a distance of less than 1 mm from the gas outlet surface.During a coating process carried out in the process chamber, which in particular does not involve plasma activation, the plasma electrode can preferably be arranged in the contact position. Decomposition products can be deposited on the surface of the plasma electrode facing away from the gas outlet of the gas inlet. The clearance can be increased or decreased by vertically moving the plate. Lifting elements can be provided with which the plasma electrode can be moved vertically. The lifting elements can be insulators or conductors with which the plasma electrode is connected to the plasma generator. The lifting elements can extend from the ceiling, the side walls, or the bottom of the reactor housing. The plate can be moved by means of an electric drive connected to the lifting elements or manually.The plasma electrode can preferably be positioned at a distance from the gas outlet surface of the gas inlet element if a process carried out in the process chamber involves igniting a plasma. In particular, the plasma electrode can only be energized when it is positioned at a distance from the gas outlet surface. For plasma ignition, the distance between the upper surface of the plasma electrode and the gas outlet surface can be, for example, between 1 and 75 mm. If only a process without the use of plasma is carried out in the process chamber, the plasma electrode preferably assumes a small distance, in particular less than 1 mm, from the underside of the gas inlet element, or a contact or bearing position in which the upper surface of the plasma electrode is at least partially in contact with the underside of the gas inlet element facing the process chamber.

[0015] The plasma electrode can be heated by the susceptor, for example, by thermal radiation, conduction, induction heating, or by light heating or embedded heating elements, either in the plasma electrode itself or in the susceptor. The gas flowing from the gas inlet can be introduced into the process chamber through gas outlet openings formed by the plasma electrode. The surface temperature of the plasma electrode can be changed by varying the distance between the plate and the heated susceptor, the susceptor temperature, or the temperature of the heating device. Furthermore, the surface temperature of the plasma electrode can also be adjusted by plasma heating, whereby the power applied to the plasma electrode is varied.

[0016] To ignite a plasma in the process chamber, a counter electrode is required. The gas inlet, the housing wall surrounding the process chamber, and / or the susceptor can serve as the counter electrode. Alternatively, another component made of an electrically conductive material and located within the process chamber, but insulated from the plasma electrode, can be used. The counter electrodes can each be grounded.

[0017] A second embodiment of the invention can provide a plasma electrode that is movable within the process chamber of a planetary reactor. The plasma electrode can be an annular plate or grid arrangement extending around the gas inlet element located in the center of the process chamber. Such an annular plate or ring arrangement can be positioned between a process chamber ceiling that bounds the process chamber upwards and a susceptor that bounds the process chamber downwards. The plasma electrode can extend over the entire cross-section of the susceptor surrounding the gas inlet element. Lifting elements can also be provided here, allowing the height of the plasma electrode within the process chamber to be adjusted.

[0018] The plasma electrode can preferably be arranged at a distance from the process chamber ceiling and the susceptor. In another operating position, the plasma electrode can be in contact with the process chamber ceiling. The process chamber ceiling, the susceptor, and the housing wall surrounding the process chamber can each function as a counter electrode.

[0019] The plasma electrode can be, for example, a plate made of graphite or coated graphite. For instance, the plasma electrode could be a graphite plate coated with SiC or TaC. It can also be made of a metal, such as tungsten (W), molybdenum (Mo), or stainless steel (SS). The plate can also be made of a conductive, refractory material, such as tungsten carbide (WC) or molybdenum steel.

[0020] The plasma generated in the process chamber by the plasma electrode can be used, for example, to produce a cleaning gas. A cleaning step can be performed in the process chamber before or after a coating step, in which the gas introduced into the chamber is converted into cleaning radicals or ions. These cleaning radicals can be used to remove residues from the surface of the plasma electrode or other surfaces in the process chamber, for example, through a chemical reaction or ion bombardment. Suitable cleaning gases include halogen gases, reducing gases, oxidizing gases, gases suitable for ion bombardment, or mixtures or compounds thereof. The cleaning gases can be introduced into the process chamber together with a carrier gas.Volatile reaction products from the cleaning reactions can be removed from the process chamber using the carrier gas. For example, a gas mixture containing chlorine gas (Cl₂), oxygen (O₂), and nitrogen (N₂) can be used as the cleaning gas. For example, the gas mixture used for cleaning can contain 20% to 80% Cl₂, 5% to 50% O₂, and 0% to 50% N₂, or in particular, 60% Cl₂, 8% O₂, and 32% N₂.

[0021] The plasma electrode can be moved within the process chamber and precisely directed towards the surface to be cleaned. The distance between the plasma electrode and the surface to be cleaned is preferably adjusted such that the plasma interacts with the surface to remove any residues present. For example, to clean the surface of the susceptor or the surface of substrates mounted on the susceptor, the plate can be moved onto the susceptor.

[0022] The plasma generated by the movable plasma electrode within the process chamber can also be used to associate or dissociate other gases introduced into the process chamber, such as precursor gases used in coating processes. In this way, the activation, i.e., the chemical decomposition of the precursor gases, can be carried out thermally and / or by means of the plasma.

[0023] The invention further provides a method for cleaning surfaces in a device as previously described. The initial position can be one in which the plasma electrode touches or rests against the underside of the gas inlet element, or is arranged at a small distance, in particular less than 1 mm, from the underside. In a first step of the method according to the invention, the plasma electrode, which is in particular designed as a plate, can be moved to a first position at a distance, in particular more than 1 mm, from the gas outlet surface of the gas inlet element. In this first position, the plasma electrode preferably has a smaller distance to the gas outlet surface than to the bottom of the process chamber or to the susceptor.

[0024] In a second step, a first cleaning gas can be fed into the process chamber, which is activated by exposure to a plasma generated by the plasma electrode. The gas inlet and / or the wall and / or the floor of the process chamber can serve as the counter electrode. The plasma can form between the plasma electrode and the nearest component, in this example the gas inlet or the gas outlet surface of the gas inlet.

[0025] The voltage or power can be selectively increased until the plasma extends both above and below the plasma electrode, including the area between the plasma electrode and the susceptor. The plasma can completely surround the plasma electrode. The radicals generated by the plasma activation of the first cleaning gas can be used to remove residues, particularly on the underside of the gas inlet facing the process chamber, as well as on the top and bottom surfaces of the plasma electrode.

[0026] In a third step, the plasma electrode can be moved to a second spacing position, in which the plasma electrode has a greater distance to the gas outlet surface than in the first position. Alternatively, in the second spacing position, the process chamber floor or the susceptor can be moved towards the plasma electrode, so that the vertical distance of the plate to the process chamber floor or the susceptor is smaller than in the first spacing position, with the distance between the plate and the gas outlet surface corresponding to the first spacing.In the second spacing position, the distance between the plasma electrode and the gas outlet surface can preferably be greater than the distance between the plasma electrode and the susceptor. This allows a plasma generated in a fourth step to initially form between the plasma electrode and the susceptor. In this fourth step, the plasma primarily cleans the surface of the susceptor and the surface of the plate facing the susceptor. Due to the smaller distance between the plate and the heated susceptor compared to the first spacing position, the surface temperature of the plate is higher, thus facilitating the cleaning of the underside of the plate.

[0027] In the fourth step, the voltage or power can be increased to such an extent that the plasma also forms above the plate, i.e., in the area between the plate and the gas inlet. This allows the surface of the plate facing the gas inlet to be cleaned as well.

[0028] In the fourth step, a second cleaning gas is introduced into the process chamber. This gas can be different from or the same as the first. The second cleaning gas can be activated by being exposed to a plasma generated by the plasma electrode, causing the formation of cleaning radicals that can be used for the previously described cleaning of the process chamber surfaces.

[0029] In the fourth step, the surfaces of substrates deposited from the susceptor can also be cleaned using the plasma. Layers deposited on the substrates, native oxides, or contaminants can also be partially or completely removed.

[0030] The cleaning steps described above can also be carried out in a different order; for example, the plasma electrode can first be moved to the second distance position and the susceptor or plasma electrode cleaned, and then moved to the first distance position to clean the gas inlet device.

[0031] In a further embodiment of the method according to the invention, a coating process can be carried out on substrates in the cleaned process chamber after the surfaces have been cleaned. For this purpose, the plasma electrode can be moved from the first or second spacing position to a contact position in which the upper side of the plasma electrode is at least partially in contact with the underside of the gas inlet element, i.e., the gas outlet surface, or is spaced at a small distance, in particular less than 1 mm, from the gas outlet surface.To clean the surface of substrates mounted on the susceptor, suitable cleaning gases include reducing gases, such as hydrogen (H₂) or ammonia (NH₃), halogen gases, such as chlorine (Cl₂) or nitrogen trifluoride (NF₃), sulfur hexafluoride (SF₆) or tetrafluoromethane (CF₄), oxidizing gases, such as oxygen (O₂), or gases suitable for ion bombardment, such as argon (Ar) or mixtures or compounds thereof. The cleaning gases can optionally be introduced into the process chamber together with a carrier gas, such as nitrogen (N₂). After the substrate cleaning step, the plasma electrode can be returned to its original position.Following the relocation of the plasma electrode to the system position, one or more process gases can be introduced into the process chamber, which, through thermal activation, form decomposition products that are deposited as a layer on substrates located on the susceptor.

[0032] In a further embodiment of the invention, the plasma electrode can be positioned at a distance from the gas outlet surface. Subsequently, one or more process gases can be fed into the process chamber, where they are decomposed by a plasma generated by the plasma electrode. The decomposition products are then deposited on the surface of the substrates, forming a coating. Here, the plasma activation of the gases introduced into the process chamber, carried out in the position at a distance, can be combined with the thermal activation of the gases without plasma activation, in which the plasma electrode, particularly in the contact position, rests against the underside of the gas inlet element. Brief description of the drawings

[0033] Exemplary embodiments of the invention are explained with reference to the accompanying drawings. These show: Fig. 1 schematically a cross-section of a process chamber 4 of a CVD reactor 3, with a gas inlet element 5 designed as an example showerhead, wherein a plasma electrode 10, height-adjustable by means of lifting elements 17, is arranged between the gas inlet element 5 and a susceptor 11 which limits the process chamber 4 downwards, and which has a distance H1 to the gas outlet surface 8, Fig. 2 a schematic representation according to Fig. 1, wherein the distance H1 of the plasma electrode 10 to the gas outlet surface 8 is greater than the distance in the Fig. 1 shown vertical position of the plasma electrode 10, Fig. 3 schematically a cross-section of a further embodiment according to the invention of a CVD reactor 3 designed as a planetary reactor, wherein the plasma electrode 10 is designed as an annular plate which is arranged height-adjustable around the gas inlet element 5 located in the center of the process chamber 4 of the planetary reactor 3, Fig. 4 a schematic representation according to Fig. 1, wherein only one lifting element 17, 18 is provided, which is attached to the ceiling of the housing 2 of the CVD reactor 3 and holds the plate 10 in the first distance position, Fig. 5 a schematic representation according to Fig. 4, wherein the plate 10 is arranged in the second spacing position, in which the distance H1 of the plasma electrode 10 to the gas outlet surface 8 is greater than in the Fig. 4 first spacing position shown, Fig. 6 a schematic representation according to Fig. 3, wherein the plasma plate 10 is held by only one lifting element 17, 18 attached to the ceiling of the housing 2 of the CVD reactor 3. Description of the embodiments

[0034] The one in the Fig. 1 and Fig. The CVD reactor 3 shown in Figure 2 has a gas-tight housing 2 in which a process chamber 4 is arranged. The process chamber 4 is bounded above by a gas outlet surface 8 of a gas inlet device 5 and below by a susceptor 11. The height H2 of the process chamber 4 thus corresponds to the vertical distance between the gas outlet surface 8 and the susceptor 11. A plasma electrode 10, designed as a plate extending in the horizontal direction, is arranged between the gas outlet surface 8 of the gas inlet device 5 and the susceptor 11. The plasma electrode 10 is arranged at a distance H1 from the gas outlet surface 8 and extends parallel to the gas outlet surface 8.

[0035] The gas inlet element 5 is designed in an exemplary showerhead shape, so that the gas inlet element 5 is also referred to as a showerhead. The showerhead shown here is an example only. The showerhead can also have a different design known from the prior art, for example as disclosed in DE 10 2021 114 868 A1. A gas outlet surface 8 extends along the underside of the gas inlet element 5, which has a plurality of gas outlet openings 6 through which gases fed into a gas distribution chamber 20 arranged above the gas outlet surface 8 can be introduced into the process chamber 4. A supply line 14 opens into the gas distribution chamber 20. Several supply lines can also be provided, each connected to a gas distribution chamber 20. Gases supplied from various gas sources 15, 21 can be fed into the gas distribution chamber 20 through the supply lines 14.Gases can be discharged from process chamber 4 via a gas outlet 27. The gases fed into process chamber 4 flow through gas outlet openings 7 arranged in the plasma electrode 10 into a lower section 4' of process chamber 4. The gases can also flow laterally past the plasma electrode 10 into the lower section 4'.

[0036] The process chamber 4 is enclosed by a wall 12. The gas inlet element 5, the wall 12, and the susceptor 11 are grounded and function as counter electrodes to the plasma electrode 10. The counter electrodes 5, 11, 12 are each grounded by means of a grounding cable or grounding connection, which is electrically connected to the respective counter electrode 5, 11, 12 via a contact 23, 24, 25.

[0037] The plasma electrode 10 is electrically connected to a plasma generator 9 by means of a contact element 19, shown here by way of example as a spring. The plasma generator 9 can be used to apply a voltage to the plasma electrode 10. The plasma electrode 10 is configured to apply energy to a gaseous feedstock to generate a plasma. The contact element 19 is electrically insulated from the housing 2. The contact element 19 is guided through a channel formed by the gas inlet 5, and is also electrically insulated from the gas inlet 5, so that the plate 19 contacted by the contact element 19 is electrically insulated from the gas inlet 5 and the housing 2 of the CVD reactor.

[0038] The gas outlet surface 8 is cooled by a cooling element (not shown). The susceptor 11 is heated by a heating device 16. The temperature of the heating device 16 is preferably selected such that the temperature of the surfaces to be cleaned in the process chamber 4 is above the sublimation temperature and / or evaporation temperature of any intermediate products, such as metal chlorides, which are formed by the reaction of the cleaning gases or radicals with parasitic deposits on the surfaces. The plasma electrode 10 is located in the Fig. 1 and Fig. 2 distance positions shown, in which the plasma electrode 10 is arranged at a distance H1 from the gas outlet surface 8 of the gas inlet organ 5, is thermally and electrically decoupled from the cooled gas outlet surface 8 and is heated by thermal conduction or by thermal radiation from the susceptor 11.

[0039] The plasma electrode 10 is designed here as a thin, circular plate and, according to the invention, is arranged in the process chamber 4 in a height-adjustable manner. The plate 10 is supported by retaining elements 18, which can be moved vertically by means of lifting elements 17. The plate 10 can also have a different design, for example as disclosed in DE 10 2021 114 868 A1.

[0040] In Fig. In a first position, the plasma electrode 10, hereinafter also referred to as plate or plasma plate, is arranged in a first spaced position in which the plasma plate 10 has a vertical distance H1 to the gas outlet surface 8. The plasma plate 10 is preferably moved into this position from a contact position in which the distance H1 is preferably less than 1 mm or the plasma plate 10 is at least partially in contact with the gas outlet surface 8 of the gas inlet element 5. In the first spaced position, the distance H1 between the plasma electrode 10 and the gas outlet surface 8 is preferably greater than 1 mm. To ignite a plasma, gas is first introduced into the gap between the plasma plate 10 and the gas outlet surface 8 by means of the gas inlet element 5. This gas flows through the gas outlet openings 7 arranged in the plasma plate 10 into the lower section 4' of the process chamber 4.To ignite a plasma, the plasma electrode 10 is subjected to a voltage by the generator 9. The resulting electric field ignites the plasma. Since in the in . Fig. In the first position of the plasma electrode 10 shown in Figure 1, where the gas inlet element 5 is the counter electrode closest to the plasma electrode 10, the plasma initially forms in the area between the gas inlet element 5 and the plate 10. By increasing the voltage or power, the plasma's propagation area can be further increased so that the plasma can also spread into the lower section 4' of the process chamber 4, i.e., between the plate 10 and the susceptor 11.

[0041] In the first position, the gas outlet surface 8 of the gas inlet organ 5 or the upper surface of the plasma electrode facing the gas outlet surface can be effectively cleaned by means of radicals generated during the plasma activation of the gas introduced into the process chamber 4. By increasing the voltage and the associated increased plasma propagation, not only the upper surface of the plasma electrode plate 10 facing the gas outlet surface 8 is cleaned, but also the underside of the plasma electrode plate 10 facing the susceptor 11. Thus, the entire plasma electrode plate 10 is cleaned.

[0042] In the Fig. 2 The plasma electrode 10 is arranged in a second distance position to the gas outlet surface 8, in which the distance H1 of the plasma electrode 10 to the gas outlet surface 8 is greater than the distance H1 that the plasma electrode plate 10 in the Fig. The first distance position shown in Figure 1 is assumed. The distance H1 is greater than the distance H3 between the plate 10 and the susceptor 11, i.e., the height H3 of the lower section 4' of the process chamber 4, so that a plasma ignited in the process chamber 4 initially forms between the susceptor 11, which acts as a counter electrode, and the plate 10. This plasma can be used to clean the surface of the susceptor 11 and / or the plasma electrode plate 10 itself, the latter having a higher surface temperature due to the smaller distance H3 to the heated susceptor 11 compared to the first distance position, which facilitates the cleaning of the plate 10.

[0043] Alternatively, starting from the first spacing position, the process chamber floor 11 or the susceptor 11 can be moved towards the plate 10 in order to reduce the distance H3 between the plate 10 and the heated susceptor 11.

[0044] If one or more substrates 1 are arranged on the susceptor 11, the plasma electrode 10, positioned vertically away from the gas outlet surface 8, can also be used to generate a plasma for pre-cleaning the surface of the substrates 1 or for removing layers deposited on the substrates 1. Such a pre-cleaning step is often necessary to remove organic residues or native oxides that may be present on the substrates due to storage in ambient conditions. After pre-cleaning, the plasma electrode 10 is moved back into the contact position (not shown here), in which the plasma electrode 10 is at least partially in contact with the gas outlet surface 8 or is positioned at a distance H1 of, in particular, less than 1 mm from the gas outlet surface 8, in order to deposit layers onto the cleaned substrates 1 in a coating process.

[0045] Furthermore, according to the invention, it is particularly provided to combine a coating process with a plasma-activated coating process. In a first step of such a process, the plasma electrode 10 is arranged in the contact position, i.e., in contact with or at a small distance H1 of less than 1 mm to the gas outlet surface 8. In a second step, the plasma electrode is then moved away from the gas outlet surface 8 to a distance position in which the distance H1 is greater than 1 mm in order to generate a plasma during the coating.

[0046] In Fig. Figure 3 shows a further embodiment in which several substrates 1 are arranged planetarily around the gas inlet element 5 located in the center of the process chamber 4, on which the susceptor 11 forms the lower boundary of the process chamber 4. These substrates are supported on bearing positions 31. By means of a shaft 13, which is rotatably driven by a rotary drive 26 and is fixedly connected to the susceptor 11, the susceptor 11 and thus the substrates 1 supported on the susceptor 11 can be rotated about a rotational axis D located in the center of the process chamber 4. Therefore, this is referred to as a "planetary reactor" in the following.

[0047] The process chamber 4 is bounded at the top by a process chamber ceiling 30. A height-adjustable plasma electrode 10 is arranged between the process chamber ceiling 30 and the susceptor 11, which is heated by the heating device 16. The plasma electrode 10 is designed as an annular plate that extends around the gas inlet element. The vertical distance H1 of the plate 10 to the gas outlet surface 8 of the gas inlet element 5 can be varied by means of the lifting elements 17.

[0048] The process chamber ceiling 30, the wall 12 surrounding the process chamber 4, and the susceptor 11 optionally function as counter electrodes for the plasma electrode 10. The counter electrodes 11, 12, 30 are, as in the one described in the Fig. 1 and Fig. 2 illustrated embodiment, grounded.

[0049] The plasma electrode 10 is, by default, arranged in the contact position, in which the plasma electrode 10 rests against the gas outlet surface 8 of the gas inlet device 5 or has a distance of, in particular, less than 1 mm to the gas outlet surface 8. For a process that includes plasma excitation, the plasma electrode is moved to a position at a distance from the gas outlet surface 8, in which the plasma electrode plate has a distance H1 of, in particular, more than 1 mm to the gas outlet surface 8.

[0050] Depending on which surface in the process chamber 4 is to be cleaned, or depending on whether substrates 1 located on the susceptor 11 are to be cleaned or layers deposited on the substrates 1 are to be treated, the plate 10 can be moved either towards the process chamber ceiling 30 or towards the susceptor 11.

[0051] In the exemplary embodiments, the plasma electrode 10 can be in contact with the process chamber ceiling 30 or the gas outlet surface 8, at least in some areas, when depositing layers in the process chamber 4.

[0052] The lifting element 17, 18 can be used as an electrical contact to the plasma electrode 10 or can be insulating. In the Fig. 1, Fig. 2 and Fig. In the three illustrated embodiments, the plate 10 is supported by retaining elements 18, which can be moved vertically by means of lifting elements 17 arranged on the bottom of the housing 2 of the CVD reactor. More or fewer retaining elements 17, 18 can also be provided. The plate 10 is, as in the Fig. 1, Fig. 2 and Fig. 3 shown supported at least at two support points by the retaining elements 18.

[0053] The Fig. 4, Fig. 5 and Fig. Figure 6 shows further embodiments of the invention. Fig. 4 and Fig. 5 essentially correspond to the Fig. 1 and Fig. 2 and the Fig. 6 of the Fig. 3, where unlike those in the Fig. 1, Fig. 2 and Fig. In the three illustrated embodiments, only one lifting element 17, 18 is provided, which is also attached to the ceiling of the housing 2 of the CVD reactor 3 and holds the plasma plate 10 at only one support point. However, more than one lifting element 17, 18 can also be provided, which hold the plate 10 at different support points. The support points can, for example, be arranged at opposite edge points of the plate 10.

[0054] The foregoing statements serve to explain the inventions covered by the application as a whole, which each independently further develop the prior art at least through the following combinations of features, whereby two, several or all of these combinations of features may also be combined, namely:

[0055] A device characterized in that the plasma electrode 10 is arranged in a displaceable manner in the process chamber 4.

[0056] A device characterized in that the plasma electrode 10 is a plate arranged between the gas outlet surface 8 of the gas inlet organ 5 and a susceptor 11 which limits the process chamber 4 downwards.

[0057] A device characterized in that a wall 12 surrounding the process chamber 4 and / or a susceptor 11 limiting the process chamber 4 downwards and / or the gas inlet element 5 and / or the process chamber ceiling 30 forms a grounded counter electrode.

[0058] A device characterized in that the plasma electrode 10 is height-adjustable by means of lifting elements 17.

[0059] A device characterized in that the plasma electrode 10 has a plurality of gas outlet openings 7.

[0060] A device characterized in that the plasma electrode 10, starting from a contact position in which the plasma electrode 10 is at least partially in contact with the gas outlet surface 8 of the gas inlet element 5 or the process chamber ceiling 30, or is arranged at a distance H1 to the gas outlet surface 8 or process chamber ceiling 30, which is in particular less than 1 mm, can be moved to one or more distance positions to the gas outlet surface 8 of the gas inlet element 5 for the purpose of generating the plasma, in which the distance H1 of the plasma electrode 10 to the gas outlet surface 8 is in particular greater than 1 mm.

[0061] A method for cleaning surfaces in a process chamber 4 of a device according to one of the preceding claims, comprising the following steps: positioning the plasma electrode 10 starting from a contact position in which the plasma electrode 10 is at least partially in contact with the gas outlet surface 8 of the gas inlet element 5 or the process chamber ceiling 30, or is arranged at a distance H1 to the gas outlet surface 8 or the process chamber ceiling 30, which is in particular less than 1 mm, in a first distance position in which the distance H1 of the plasma electrode 10 to the gas outlet surface 8 is greater than in the contact position, in particular greater than 1 mm; introducing a first cleaning gas into the process chamber 4; plasma activation of the first cleaning gas by applying a voltage to the plasma electrode 10, so that radicals are formed;Removal of residues from the surfaces by reaction with the radicals, in particular from the gas outlet surface 8 of the gas inlet organ 5 and / or the process chamber ceiling (30) and / or the plasma electrode 10 and / or the susceptor 11.;

[0062] A method characterized by the following further steps: positioning the plasma electrode 10 in a second spacing position or relocating the susceptor 11, which delimits the process chamber 4 downwards, to a position in which the first plasma electrode 10 has a smaller distance H3 to the susceptor 11 compared to the first spacing position; introducing the first or a second cleaning gas into the process chamber 4; activating the first or second cleaning gas by a plasma generated by the plasma electrode 10, so that radicals are formed; removing residues from the surfaces, in particular from the plasma electrode 10 and the susceptor 11.

[0063] A process characterized in that the first cleaning gas and / or the second cleaning gas is a halogen gas or a reducing or oxidizing gas or a gas suitable for ion bombardment, or mixtures or compounds thereof, which is optionally fed into the process chamber 4 together with a carrier gas.

[0064] A method characterized in that, in the first and / or second spacing position, residues on surfaces of one or more substrates 1 located on the process chamber floor 11 and / or optionally one or more layers deposited on the substrates 1 are removed with the generated radicals.

[0065] A method characterized in that, after cleaning, a coating process is carried out in the process chamber 4, wherein the plasma electrode 10 is moved into a position in which a top surface of the plasma electrode 10 is at least partially in contact with the gas outlet surface 8 or the process chamber ceiling 30, or is arranged at a distance H1 of less than 1 mm from the gas outlet surface 8 or the process chamber ceiling 30, wherein one or more process gases are introduced into the process chamber 4, wherein decomposition products of the process gases are deposited as a layer on the substrates.

[0066] A method for depositing a layer on a substrate 1 in a process chamber 4 of a CVD reactor 3 according to any one of claims 1 to 5, wherein the process chamber 4 is bounded downwards by a process chamber floor 11 on which one or more substrates 1 are arranged, comprising the following steps: positioning the plasma electrode 10 bounding the process chamber 4 upwards in a spaced position in which the plasma electrode 10 is arranged at an electrically insulating distance to the gas outlet surface 8; introducing one or more process gases into the process chamber 4, wherein the process gases are decomposed by a plasma generated by the plasma electrode 10, the decomposition products of the process gases growing onto the surface of the substrates 1 to form a coating.

[0067] A method characterized in that the voltage or power acting on the plasma electrode 10 is increased in such a way that the plasma spreads both above and below the plasma electrode 10.

[0068] All disclosed features are essential to the invention (individually, but also in combination with one another). The disclosure of this application hereby incorporates in full the disclosure content of the associated / attached priority documents (copy of the earlier application), also for the purpose of including features of these documents in the claims of the present application. The dependent claims, even without the features of a referenced claim, characterize independent inventive developments of the prior art, in particular for the purpose of filing divisional applications based on these claims. The invention specified in each claim may additionally comprise one or more of the features described above, in particular those identified by reference numerals and / or listed in the reference numeral list.The invention also relates to design forms in which individual features mentioned in the preceding description are not realized, in particular insofar as they are recognizably unnecessary for the respective purpose or can be replaced by other technically equivalent means. List of reference symbols 1 substrate 2 cases 3 CVD reactor 4th Trial Chamber 4' lower section of the trial chamber 5 Gas inlet device 6 Gas outlet opening 7 Gas outlet opening 8 Gas outlet area 9 Plasma generator 10 Plasma electrode / plate 11 Susceptor 12 wall 13 shaft 14 Supply line 15 Gas source 16 Heating system 17 Lifting element 18 retaining elements 19 Contact element 20 Gas distribution chamber 21 Gas source 22 Contact 23 Contact 24 Contact 25 Contact 26 Rotary drive 27 Gas outlet 28 Mass flow controllers 29 Mass flow controllers 30 Process chamber ceiling 31 substrate storage space H1 gap height H2 Height Process Chamber H3 Height of the lower section 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] EP 2 876 083 B1

[0004] US 2002 / 012976 A1

[0005] US 2010 / 0072054 A1

[0006] DE 10 2011 056 589 A1

[0007] DE 10 2021 114 868 A1 [0012, 0035, 0039] Cited Non-Patent Literature

[0000] Li et al. (Li, S., Tompa, GS, Moy, K. et al. In-situ plasma cleaning of stainless steel III-V MOCVD growth systems. J. Electron. Mater. 21, 149-156 (1992). https: / / doi.org / 10.1007 / BF02655830

[0008]

Claims

[1] Device for depositing a layer on a substrate (1) in a process chamber (4) arranged in a housing (2) of a CVD reactor (3), with a gas inlet device (5) for introducing gases into the process chamber (4), with a gas outlet surface (8) having a multitude of gas outlet openings (6, 7) through which the gases can flow into the process chamber (4), with at least one plasma electrode (10) which can be supplied with an electrical voltage by a plasma generator (9) and which is designed to supply energy to a gaseous starting material in order to generate a plasma, characterized by , that the plasma electrode (10) is arranged in a movable manner in the process chamber (4). [2] Device according to claim 1, characterized by, that the plasma electrode (10) is a plate arranged between the gas outlet surface (8) of the gas inlet organ (5) or a process chamber ceiling (30) and a susceptor (11) that limits the process chamber (4) downwards. [3] Device according to any one of the preceding claims, characterized by , that a wall (12) surrounding the process chamber (4) and / or a susceptor (11) limiting the process chamber (4) downwards and / or the gas inlet element (5) and / or the process chamber ceiling (30) forms a grounded counter electrode. [4] Device according to any one of the preceding claims, characterized by , that the plasma electrode (10) is height-adjustable by means of lifting elements (17). [5] Device according to any one of the preceding claims, characterized by , that the plasma electrode (10) has a plurality of gas outlet openings (7). [6] Device according to any one of the preceding claims, characterized by, that the plasma electrode (10) can be moved from a contact position in which the plasma electrode (10) is at least partially in contact with the gas outlet surface (8) of the gas inlet element (5) or with the process chamber ceiling (30) or is arranged at a distance (H1) to the gas outlet surface (8) or the process chamber ceiling (30), which is in particular less than 1 mm, into one or more distance positions to the gas outlet surface (8) of the gas inlet element (5) in which the distance (H1) of the plasma electrode (10) to the gas outlet surface (8) is in particular greater than 1 mm. [7] A method for cleaning surfaces in a process chamber (4) of a device according to one of the preceding claims, comprising the following steps: Positioning the plasma electrode (10) starting from a contact position in which the plasma electrode (10) is at least partially in contact with the gas outlet surface (8) of the gas inlet device (5) or is arranged at a distance (H1) to the gas outlet surface (8) or the process chamber ceiling (30), which is in particular less than 1 mm, in a first distance position in which the distance (H1) of the plasma electrode (10) to the gas outlet surface (8) or the process chamber ceiling (30) is greater than in the contact position, in particular greater than 1 mm; Introducing a first cleaning gas into the process chamber (4); Plasma activation of the first purification gas by applying a voltage to the plasma electrode (10) so that radicals are formed; Removal of residues from the surfaces by reaction with the radicals, in particular from the gas outlet surface (8) of the gas inlet device (5) and / or the process chamber ceiling (30) and / or the plasma electrode (10) and / or the susceptor (11). [8] Method according to claim 7, characterized by the following further steps: Positioning the plasma electrode (10) in a second spacing position or relocating the susceptor (11) which delimits the process chamber (4) downwards to a position in which the first plasma electrode (10) has a smaller distance (H3) to the susceptor (11) compared to the first spacing position; introducing the first or a second cleaning gas into the process chamber (4); activating the first or second cleaning gas by a plasma generated by the plasma electrode (10) so that radicals are formed; removing residues from the surfaces, in particular from the plasma electrode (10) and the susceptor (11). [9] Method according to claim 7, characterized by , that the first cleaning gas and / or the second cleaning gas is a halogen gas or a reducing or oxidizing gas or a gas suitable for ion bombardment or mixtures or compounds thereof, which may be fed into the process chamber (4) together with a carrier gas. [10] Method according to claim 8 or 9, characterized by , that in the first and / or second spacing position, residues on surfaces of one or more substrates (1) located on the process chamber floor (11) and / or possibly one or more layers deposited on the substrates (1) are removed with the generated radicals. [11] Method according to one of claims 8, 9 or 10, characterized by, that after cleaning a coating process is carried out in the process chamber (4), wherein the plasma electrode (10) is moved into a position in which a top side of the plasma electrode (10) is at least partially in contact with the gas outlet surface (8) or the process chamber ceiling (30) or is arranged at a distance (H1) of less than 1 mm from the gas outlet surface (8) or the process chamber ceiling (30), wherein one or more process gases are introduced into the process chamber (4), where decomposition products of the process gases are deposited as a layer on the substrates. [12] Method for depositing a layer on a substrate (1) in a process chamber (4) of a CVD reactor (3) according to any one of claims 1 to 5, wherein the process chamber (4) is bounded downwards by a process chamber floor (11) on which one or more substrates (1) are arranged, comprising the following steps: Positioning the plasma electrode (10) which defines the upper boundary of the process chamber (4) in a position where the plasma electrode (10) is arranged at an electrically insulating distance to the gas outlet surface (8) or the process chamber ceiling (30); Introducing one or more process gases into the process chamber (4), wherein the process gases are decomposed by a plasma generated by the plasma electrode (10), wherein the decomposition products of the process gases grow on the surface of the substrates (1) forming a coating. [13] Method according to any one of claims 8 to 12, characterized by , that the voltage or power acting on the plasma electrode (10) is increased in such a way that the plasma spreads both above and below the plasma electrode (10). [14] apparatus or method, characterized by one or more of the characterizing features of any of the preceding claims.

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