Method and device for coating a structured substrate and substrate for carrying out the method

Abstract

The invention relates to a method for depositing one or more layers (28, 29) on a substrate in a CVD reactor (1). Using an optical measuring device (13, 14, 15), an optical measurement value is determined on the upper side of the moving substrate at a measuring point (23, 24, 25) fixed to the housing. In order to be able to carry out this method even with structured substrates (12), it is proposed that the structural elements (21) influencing the optical measurement value do not extend over the entire surface of the substrate (21), but that one or more measuring surfaces (18, 19, 20) are free of these structural elements (21), wherein the optical measurement values are then determined at least on one of the measuring surfaces (18, 19, 20). A computing device (30) can distinguish between the measured values determined at the measuring surfaces (18, 19, 20) and those determined at the structured areas of the upper side of the substrate (12).The invention further relates to a substrate (12) structured in this way.

Description

field of technology

[0001] The invention relates to a method for depositing one or more layers on at least one substrate in a CVD reactor. The CVD reactor has a housing. A process chamber is located within the housing. The floor of the process chamber is formed by a susceptor. The susceptor can be driven in rotation about a rotation axis by a rotary drive. The susceptor supports one or more substrates and is heated by a heating device. A gas inlet element is provided, through which a process gas containing reactive gases is fed into the process chamber. The reactive gases react in the process chamber and in particular on the surface of the substrate heated to a process temperature in such a way that decomposition products of the reactive gases condense as a layer, in particular a crystalline layer, on the surface of the substrate or on a layer already deposited on the surface of the substrate.The process temperature is regulated to a target temperature by controlling the heating device. The actual temperature of the upper side of the substrate facing the process chamber is measured using an optical measuring device. The optical measuring device measures both an emissivity value and a reflectivity value at a measuring point on the surface of the layer growing on top of the moving substrate. The emissivity value can be considered the base value for the pyrometric determination of the temperature. The reflectivity value can be used to make a correction. A laser can be used to determine the reflectivity value, illuminating the surface at the measuring point fixed to the housing. State of the art

[0002] Such a method is described in DE 10 2018 106 481 A1. DE 10 2018 125 431 A1 describes a method for controlling the temperature in a CVD reactor. Summary of the invention

[0003] The invention is based on the object of developing the method described at the outset, by means of which layers with large-area smooth surfaces are applied to a substrate, in such a way as to also coat substrates having structural elements and to provide a device suitable for this purpose.

[0004] The problem is solved by the invention specified in the claims, wherein the subclaims are not only advantageous developments of the independent claims, but also independent solutions to the problem.

[0005] The substrates to be coated according to the invention have structural elements that can be formed by GaN columns, microcolumns, nanocolumns, nanowires, pyramids, depressions, two-dimensional structures, or the like. A method for depositing columnar structures is described, for example, in DE 10 2014 109 335 A1. The substrates to be coated are, in particular, precursors for micro-LED technology. However, structured substrates such as HEMT or 2D can also be used. The structures can have a characteristic lateral length of 1 nm to 100 µm. The structures can be deposited in a preliminary process, in particular using masks. However, it is also possible for the structures to be exposed from a previously deposited layer by an etching process. The substrates can consist of a IV material, a III-V material, or a II-VI material.The structural elements are particularly regularly arranged and can consist of a IV material, a III-V material, or a II-VI material. These structural elements influence the optical measurement value determined by the optical measuring device for determining the surface temperature or a curvature of the substrate.

[0006] US 11,063,181 B2 describes a substrate structured with columnar structures or depressions.

[0007] US 11,600,538 B2 describes a method for determining electronic measurement values ​​on measuring surfaces of a layer deposited on a substrate.

[0008] The method according to the invention initially and essentially provides that the upper side of the substrate is not completely structured with the structural elements, but that the surface has one or more measuring surfaces where the upper side is in particular unstructured, but is in any case designed such that the optical measured values ​​obtained there can be used to determine, for example, a surface temperature or a curvature of the substrate. The optical measured value is determined on at least one of these measuring surfaces. The optical measuring device can be a pyrometer arranged outside the process chamber. There is an optical path between the optical measuring device and the measuring point at which the optical measurement is taken on the upper side of the substrate, for example the measurement of a reflectivity value and an emissivity value. To measure the reflectivity value, the upper side of the substrate is illuminated at the measuring point.In particular, the measuring point is fixed to the housing. It then does not change its position relative to the housing. Its position is only fixed relative to the substrate if it lies in the axis of rotation of the substrate or of the susceptor on which at least one substrate rests. However, the optical measuring device is configured such that when the substrate moves, the measuring point moves relative to the moving surface of the substrate. If it is sufficient to determine only one measured value on the top side of the substrate, the measuring surface can be located in the axis of rotation of the susceptor. If multiple substrates are arranged on the susceptor, or if the susceptor supports a single large substrate, or if multiple heating zones are provided for heating the susceptor, it may be necessary for the measuring point to be located outside the axis of rotation, or for multiple measuring points to be required that are at a distance from the axis of rotation, i.e., arranged eccentrically.In such an arrangement, in which the measuring point, which is preferably fixed to the housing, is spaced from the axis of rotation, both structured regions of the upper side and at least one of the measuring surfaces pass the measuring point during the movement of the substrate. Optical measurement values ​​are continuously determined using the optical measuring device. The measuring point thus moves relative to the substrate, for example on a circular arc around the axis of rotation of the substrate or of the susceptor, essentially sweeping over structured regions. The measuring surface is arranged in such a way, or the substrate with the measuring surface is arranged in such a way, that during the movement of the substrate the measuring point also moves over the measuring surface. In a preferred embodiment, it is provided that the measuring surfaces rotate by the same angle of rotation within a predetermined measuring time.This means that the length of the measuring fields measured in the circumferential direction increases linearly with their distance from the center of rotation.

[0009] The measured values ​​obtained when the material passes over the structured areas of the upper side differ qualitatively and / or quantitatively from the measured values ​​obtained when the material passes over the measuring surfaces. The optical measured values ​​are evaluated by a computing device. The computing device is programmed in such a way that it can distinguish between the measured values ​​determined at the measuring surfaces and those determined at the structured areas. The computing device can therefore only use those measured values ​​determined at the measuring surfaces to calculate a temperature value or a value for a curvature of the substrate. The measured values ​​measured at the structured areas of the upper side of the substrate can be discarded. However, it is also possible to use these or the other measured values ​​to change other process parameters.

[0010] The measuring surfaces preferably have a sufficiently large smooth surface, for example at least an area of ​​1 mm 2 It is sufficient if the area is not larger than 1000 mm 2is. The surface is coated during the deposition of the layer. Areas located between the structural elements are also coated. The measuring surfaces can have a circular outline. However, the outline of the measuring surfaces can also deviate from a circular shape; for example, the radial extent of the measuring surface can be smaller than the extent of the measuring surface in the direction of rotation. The measuring surface can, for example, have an elliptical shape. It can be sufficient if the extent of the measuring surface in the circumferential direction around the axis of rotation is a maximum of 10 mm. In the radial direction, the measuring surface can be a maximum of 5 mm. The substrate can have a diameter of 30 cm. The measuring surface can be a circular segment that extends around the center of the substrate. The radial width can be up to 5 mm.The circumferential length of the measuring surface can be calculated from the rotational speed of the substrate, the radial distance, the number of measurements required for each revolution and the sensor frequency of the optical measuring device according to the following formula. dx=2π fnvrx d x Length in circumferential direction f Speed ​​(0.4 to 0.91 / sec) n Number of measuring points (1 to 6, preferably 4) v Sensor frequency (100 to 1000 / sec, preferably 200 / sec) r x Radial distance (0 to 75 mm, (preferably 44 mm); 76 to 130 mm (preferably 98 mm); 130 to 150 mm, (preferably 145 mm)).

[0011] The device for depositing layers on structured surfaces is a CVD reactor and can have a circular disk-shaped susceptor made of graphite. The surface of the susceptor can be coated. The coating can be SiC or TaC, or a mixture of these materials. The susceptor is driven by a rotary drive about a rotational axis, which can be the susceptor's axis of symmetry. The susceptor forms the floor of a process chamber. The ceiling of the process chamber can be formed by a gas inlet element, which is a showerhead. The gas inlet element has a gas outlet surface facing the process chamber, which has a plurality of evenly distributed gas outlet openings. The process gas enters the process chamber from the gas outlet openings. The gas outlet surface can be cooled.The gas inlet device has one or more gas distribution chambers into which different reactive gases are fed. The reactive gases exit the gas distribution chambers separately through the gas outlet openings. The one or more optical measuring devices can be arranged outside the housing of the CVD reactor. In this case, passage openings are provided through which an optical path passes through the gas outlet surface. The optical path extends from the measuring point to the optical measuring device. The optical measuring device can have several pyrometers that measure reflectivity or emissivity in the range of different wavelengths. A laser can be provided with which the surface is illuminated to measure reflectivity. The light from the laser is scattered more strongly in the structured areas of the upper side of the substrate than in the smooth areas in the region of the one or more measuring surfaces.The measured values ​​of the reflectivity value measured at a structured area on the top side of the substrate therefore differ at least quantitatively from the measured values ​​measured at a non-structured area on the top side of the substrate.

[0012] A heating device is located beneath the susceptor. This can be an IR heater with lamps that heat the underside of the susceptor. However, it can also be an RF heater that heats the susceptor by generating eddy currents. In particular, the heating device is provided with several separately controllable heating zones. An inner heating zone can be provided, which is located in the region of the center of the susceptor. The inner heating zone can be surrounded by a middle heating zone. The latter, in turn, can be surrounded by an outer heating zone. The several heating zones are arranged, in particular, concentrically around the axis of rotation of the susceptor. In one variant of the invention, each of the heating zones is assigned a measuring point fixed to the housing.Preferably, an optical measuring device is provided for each heating zone, with which a surface temperature of the substrate and / or a value for a local curvature of the substrate can be determined. The computing device is configured such that it uses only those optical measurement values ​​that have been determined at one of the measuring surfaces to determine the surface temperature or the curvature. A control device can be used to control the respective heating zone in such a way that the measured temperature value is adjusted to a setpoint.

[0013] In a variant of the invention, however, the measuring point can also be non-stationary. For example, means can be provided with which the laser beam or the optical path can be changed, for example, using mirrors. Then the measuring point can also record measured values ​​at different positions within the housing or on the susceptor. For example, an optical measuring device can determine measured values ​​at different heating zones.

[0014] In a variant of the invention, the gas inlet element can also be located in the center of the process chamber. The substrates can be arranged on substrate holders that are rotatable relative to a susceptor. The susceptor can rotate about an axis located at the center of the gas inlet element. The one or more measuring surfaces then move along a cycloid, with the measuring point then being located on the cycloid curve. For this purpose, it is advantageous if the rotational movement of the substrate carrier is synchronized with the rotational movement of the susceptor.

[0015] The substrate used to carry out the method has a top surface that is predominantly provided with structural elements. Only comparatively small surface sections are free of structural elements and have a smooth surface, whereby the surface extension of the measuring surfaces thus formed is sufficiently large that a temperature measurement or a measurement of a curvature of the substrate can be carried out on this measuring surface using a measuring point moving across the substrate surface, which is illuminated in particular by a laser beam. The surface extension of the measuring surface is thus preferably only slightly larger than the area of ​​the light beam illuminating the top side of the substrate, which is required for measuring the reflectivity, or the area used by the pyrometer to measure the reflectivity or emissivity.The area of ​​the measuring fields can, for example, be at least three times as large as this area, but a maximum of ten times as large. The measuring area can extend over at least 1 mm. 2 and a maximum area of ​​1000 mm 2 The area of ​​the substrate should be at least 100 cm 2The substrate can be circular disk-shaped and have a diameter greater than 20 cm. Preferably, a substrate is used which has a standard size of, for example, 30 cm in diameter. The measuring fields are arranged at different radial distances from the center of the substrate. The radial distances can have the values ​​specified above and are in particular approximately 45 mm, 100 mm and 140 mm for a substrate with a radius of 150 mm. While the method is being carried out, the substrate can be rotated about its center. The center of the substrate is preferably located on the axis of rotation. The substrate can be rotated at a speed of 30 to 60 rpm.

[0016] The substrate can be made of one of the materials mentioned above and have structural elements that are, for example, spaced-apart columns, wires, pyramids, depressions, or two-dimensional structures. The structural elements can be made of the materials mentioned above. A characteristic length, for example a diameter of a structural element, can be in the range between 10 nm and 100 µm. The height can also be in the range between 500 nm and 1,000 nm. Preferably, the characteristic length is in the range between 10 nm and 1,000 nm. A typical characteristic length is in the range between 40 and 800 nm. The distance between adjacent structural elements can be in the same range.

[0017] The height of the structural elements, for example the columns, can be in the range between 10 nm and 1000 nm. The thickness of the layer or the layer sequence consisting of several layers that is deposited onto the structural elements, for example on an upwardly facing end face, can also be in the range between 10 nm and 1000 nm. The layer or layer sequence can also be deposited onto the areas of the upper side of the substrate that lie between the structural elements, i.e. in particular also onto the measuring surfaces. The thickness of this layer or layer sequence is preferably smaller than the height of the structural elements, so that the layer deposited onto the structural elements is vertically separated from the layer forming in the intermediate space. Preferably, however, no layer growth takes place between the structural elements.

[0018] The surface of the substrates to be treated can also be formed by a mask, for example a structured mask made of SiN, SiO x , AlO xor Ti. The mask has a number of defined openings in which a layer can grow. The mask thus enables the selective growth of structural elements, for example, vertically growing columns. The mask can also have surface areas that are unstructured. These are the measuring areas described above, at which optical measurement values ​​can be determined. However, it can also be provided that the mask has second, larger openings that form the measuring areas. In the area of ​​this opening, a layer can be deposited in the process. The surface of the mask is preferably a passivated surface on which no layer growth takes place. This then means that no layers are deposited between the openings in the mask. The deposition of the layer is limited to the openings in the mask. The mask can be applied to a GaN layer.The GaN layer can be doped or undoped. The structural elements deposited in the mask openings can be columns or pyramids. However, it is also possible that the edge of the mask opening is overgrown during the deposition of the structural elements or during the deposition of layers on structural elements. For example, it is possible to deposit GaN transistors. Here, the width of the openings in the mask is in a range between 35 and 100 µm. The distance between the structural elements can be approximately 100 µm. The thickness of the columns can range from 1 to 50 µm.

[0019] In one embodiment, a silicon substrate is coated with an AlN layer and / or a GaN layer. The coated substrate is then masked with Ti. N-type GaN or GaN can grow at nucleation sites in the openings of the mask. This creates nanopillars with a height of 500 to 1,000 nm. Their diameter can be 150 to 200 nm. The distance between two nanopillars can be approximately 250 nm.

[0020] In another embodiment, a GaN layer is deposited on a silicon or sapphire substrate using a MOVPE process. A SiN mask is then deposited onto this layer. This can be done using the LPCVD process. The mask has a regular arrangement of circular openings. The openings can be created by reactive ion etching after electron beam lithography. A GaN coating is then applied. This forms a nucleation layer within the opening. Subsequently, InGaN pyramids are deposited. The diameters of the pyramids can be 500 nm. The thickness of the pyramids can be in the range of a few hundred nm. The SiN mask surface forms a passivation layer.

[0021] GaN nanowires can also be deposited. The length of the nanowires can range from a few hundred nm to a few micrometers. The spacing between the nanowires can be smaller than their height, reaching approximately 500 nm.

[0022] It is also possible to provide measuring surfaces in surface structures of sapphire, for example in PSS (patterned sapphire substrate), which do not have any structures.

[0023] The following structural elements are particularly considered: GaN columns, micro columns (micro applications), Nanopillars, nanowires (for opto applications), regrown ohmic contacts, vertical bridges (differently doped material, stacked vertically), masked or unmasked areas (with uniform growth, so that there are areas that are not structured, Measurement on the mask (roughness), III-V on 2D materials, 2D layers with free areas. Short description of the drawings

[0024] An embodiment of the invention is explained below with reference to the accompanying drawings. They show: Fig. 1 schematically shows a cross section through a housing 2 of a CVD reactor 1, Fig. 2 shows the top view of a substrate 12 used in carrying out the method, Fig. 3 shows a perspective schematic view of a section of the upper side of the substrate in the region of the edge of a measuring surface 19, Fig. 4 schematically shows a section through a substrate 12 coated with the method, Fig. 5 a representation according to Fig. 2 of a further embodiment, Fig. 6 section VI from Fig. 5. Description of the embodiments

[0025] The device for carrying out the method as described in the Fig. 1, has a housing 2 made of stainless steel and is gas-tight. Located within the housing 1 is a heating device 5 consisting of three RF coils arranged concentrically around a rotational axis D. Each of the RF coils forms a heating zone 6, 7, 8. The heating zones 6, 7, 8 are controlled by a computer device having a control device.

[0026] Above the heating device 5, which extends in a plane, is a susceptor 4 made of graphite. On its side facing away from the heating device 5, the susceptor 4 has a pocket in which a substrate 12 is located, which may, for example, have a diameter of 30 cm or more. The center Z of the substrate 12 lies on the rotation axis D, around which the susceptor 4 can be rotated using a rotary drive device (not shown).

[0027] A process chamber 3 extends above the susceptor 4, the height of which can be 1 to 3 cm. The process chamber 3 is bounded at the top by a gas inlet device 9.

[0028] The gas inlet element 9 has a flat gas outlet surface 10 facing the process chamber 3, in which a plurality of gas outlet openings 11 are located. The gas outlet openings 11 are evenly distributed over the gas outlet surface 10 and are supplied with reactive gases and inert gases from gas distribution chambers (not shown). This is achieved by supply lines 31, which are connected to a gas mixing system (not shown). Different reactive gases can be fed through the supply lines 31 into different gas distribution chambers, from which they pass through the gas outlet openings 11 into the process chamber 3.

[0029] Three pyrometers 13, 14, 15 are provided as optical measuring devices, which can be arranged outside the housing and are connected to the computing device 30. An optical path 16 extends from a measuring point 23, 24, 25 to a pyrometer 13, 14, 15 assigned to the measuring point 23, 24, 25. The optical path 16 runs through a respective passage opening 17 of the gas outlet surface 10 or the gas inlet element 9. The passage opening 17 can be formed by a sleeve.

[0030] Pyrometers 13, 14, and 15 can be multi-channel pyrometers capable of measuring both reflectivity and emissivity values ​​at measuring points 23, 24, and 25. Pyrometers 13, 14, and 15 measure temperature values. Multiple measurements can be taken consecutively at one of the measuring points 23, 24, and 25. Pyrometers 13, 14, and 15, for example, are capable of recording 200 to 1,000 readings per second. Pyrometers 13, 14, and 15 can be single-color pyrometers, allowing them to measure a non-emissivity-corrected temperature. However, pyrometers 13, 14, and 15 can also be two-color pyrometers.

[0031] The measuring points 13, 24, 25 are located on the upper side of the substrate 12 facing the process chamber 3 and are spaced from the rotation axis D by various values, so that the measuring point 23 is spatially assigned to the outer heating zone 6, the measuring point 24 to the middle heating zone 7, and the measuring point 25 to the inner heating zone 8 in order to measure the temperatures of the upper side of the substrate 12, which are influenced by the respective heating zones 6, 7, 8. A control device 32 can be used to control the temperatures of the susceptor 4 or the substrates 12 resting thereon in the heating zones 6, 7, 8.

[0032] The Fig. 2 schematically shows a plan view of the upper side of the substrate 12. The upper side of the substrate 12 is predominantly provided with structural elements 21. The Fig. Figure 3 schematically shows the structural elements 21, greatly enlarged, as columns emerging from a surface 26 of the substrate 12. Reference numerals 18, 19, 20 denote regions of the upper side of the substrate 12 that are unstructured. These regions form measuring surfaces 18, 19, 20 with a smooth surface 26. These unstructured regions can have an area between 10 and 100 mm 2 The plan of the surface may be elliptical, with the semi-major axis of the ellipse extending in the azimuthal direction relative to the center Z of the circular substrate.

[0033] Several measurements can be performed in immediate succession on each of the measuring surfaces 18, 19, and 20. Different temperature values ​​can be measured. These temperatures can be averaged.

[0034] In one variant of the invention, temperature values ​​are measured throughout the entire rotation. An average temperature can be calculated from these temperature values. It can also be provided that an offset is formed between this average temperature and the temperatures measured at the average temperature at the measuring surfaces 18, 19, 20. Such an offset can be continuously re-determined. For example, each rotation can provide an offset value.

[0035] The temperature averaged across the entire wafer can also be determined by a second sensor, such as a pyrometer or a plurality of sensors. Such an arrangement has the advantage that the average temperature can be determined more accurately.

[0036] To control the substrate temperature using the heating device 5 or the heating zones 6, 7, 8, a value can be formed which consists of the sum of the temperature value averaged over the entire revolution and the offset.

[0037] The substrate 12 is a precursor in the manufacture of micro-LEDs. Each of the columns 21 represents a red, blue, or green pixel. The diameters of the columns are preferably less than 1 µm and can be in the above-mentioned range between 10 and 100 nm. The spacing of the columns from one another can have the same values. The columns can be made of Si, GaN, or AlN. These structural elements 21 can have been deposited in a previous process step in a different or in the same CVD reactor, using masks. However, it is also possible to create the structural elements 21 by etching a previously deposited layer. Masks can also be used here.

[0038] In the method according to the invention, the substrate 12 resting on the susceptor 4 is heated to a process temperature. Together with a carrier gas, the reactive gases are fed through the gas outlet openings 11 into the process chamber 3, where the reactive gases chemically react, for example, decompose, and decomposition products are deposited on the substrate 12 as a layer 28 that glows upon excitation. The layers can consist, in particular, of GaN, AlN, InGaN, or AlGaN.

[0039] The Fig. 4 schematically shows a layer structure consisting of two layers 28, 29. A layer sequence 28, 29 deposited during the process has a layer thickness b that can be in the range between 10 and 100 nm. The previously manufactured structural elements 21, which are columns in the example, can have a height a in the range of 10 and 100 nm. It is preferred that the height a of the structural elements 21 is greater than the layer thickness b. The layer or layer sequence 28, 29 deposited on the surface 26 between the structural elements 21 then has a layer thickness that is less than the height a of the structural elements 21.

[0040] During the coating of the substrate 12, but also during the heating of the process chamber 3 prior to the actual coating process, the surface temperature of the substrate 13 is continuously measured at the three measuring points 23, 24, 25 using the optical measuring devices 13, 14, 15. Due to the rotation of the substrate 12 about the rotation axis D, which preferably coincides with the center Z of the substrate 12, the measuring points 23, 24, 25 each move along a circular track 33, 34, 35 around the center Z.

[0041] In each track 33, 34, 35, there is at least one, preferably exactly one, measuring surface 18, 19, 20, which has a smooth surface 26, i.e., is unstructured and lacks structural elements 21. While the measuring point 23, 24, 25 moves over the structured region of the upper side of the substrate 12, the optical measuring devices 13, 14, 15 determine a qualitatively and / or quantitatively different measurement signal than while the measuring point 23, 24, 25 moves over the measuring surface 18, 19, 20. The computing device 30 is capable of detecting these differences and using only the measured values ​​determined while moving over the measuring surfaces 18, 19, 20 for temperature control or for determining a curvature of the substrate.

[0042] The temperature values ​​at the measuring surfaces 18, 19, 20 determined by the computing device 30 are transmitted to the control device 32 as actual values, wherein the control device 32 regulates the surface temperatures of the substrate 12 to a desired value on the basis of these actual values ​​with the heating zones 6, 7, 8 of the heating device 5.

[0043] The invention particularly relates to a method for depositing one or more layers 28, 29 on a substrate 12 in a housing 2 of a CVD reactor 1, during which the substrate 12 is moved about a rotational axis D and an optical measurement value is determined on an upper side of the moving substrate by means of at least one optical measuring device 13, 14, 15 at at least one housing-fixed measuring point 23, 24, 25 remote from the rotational axis D, wherein the upper side of the substrate 12 is predominantly structured with structural elements 21 influencing the optical measurement value and has one or more measuring surfaces 18, 19, 20 at which the upper side is unstructured, wherein during the movement of the substrate 12 both structured regions of the upper side and at least one of the measuring surfaces 18, 19, 20 pass the measuring point 23, 24, 25, wherein the optical measuring device 13, 14,15 continuously determines optical measurement values ​​and a computing device 30 distinguishes between the measurement values ​​determined at the measuring surface 18, 19, 20 and those determined at the structured areas.

[0044] The Fig. 5 and Fig. 6 shows a further embodiment of the invention, in which the measuring surfaces 18, 19, 20 are circular segment surfaces. The width w of the circular segment surfaces is in the range between 1 mm and 5 mm. The diameter of the substrate 12 is approximately 15 mm. The radial distances of the measuring surfaces from the center Z are: Ra approximately 44 mm; Rb approximately 98 mm; and Rc approximately 140 mm.

[0045] The circumferential length d of the measuring surfaces 18, 19, 20 depends on the number of measurements taken on the measuring surface 18, 19, 20 during each revolution, the sensor frequency of the sensor, and the rotational speed of the substrate 12. Typically, the lengths da are 7 mm; db is 15 mm; and dc is 20 mm.

[0046] In one embodiment, the surface of the substrate or the surface of a base layer deposited on a substrate can be provided with a mask. The mask consists of a material whose surface has the property that no III-V layer can be deposited on it. The mask has openings that form the structural elements. Semiconductor layers can be deposited within these openings and grow as pillars on the base layer. In such an embodiment, the measuring surfaces 18, 19, 20 can either be open surfaces that are free of openings, so that an optical measurement value is measured with an optical measuring device in regions of the mask that are free of structural elements.However, it can also be provided that the mask has larger openings that form the measuring surfaces 18, 19, 20, so that an optical measuring device can measure an optical measurement value, initially on the base surface and then on the layer deposited on the base surface during the coating process. The number of measuring points measured during each revolution is preferably four. The effective measuring frequency of a sensor can be in the range between 100 and 1,000 Hz. The maximum sensor frequency can be 2,000 Hz. At a speed between 35 and 60 rpm, the length d of the measuring fields measured in the circumferential direction can then be calculated as a function of the radial distance using the formula given above.

[0047] The above statements serve to explain the inventions covered by the application as a whole, which each independently develop the state of the art by at least the following combinations of features, whereby two, several or all of these combinations of features can also be combined, namely:

[0048] A method which is characterized in that the upper side of the substrate 12 is predominantly structured with structural elements 21, wherein the structural elements 21 influence the optical measured value, and the surface has one or more measuring surfaces 18, 19, 20 at which the upper side is free of the structural elements 21 and in particular unstructured, wherein the optical measured value is determined on at least one of the measuring surfaces 18, 19, 20.

[0049] A method which is characterized in that the measuring point 23, 24, 25 which is fixed to the housing is spaced from the axis of rotation D and in that during the movement of the substrate 12 both structured regions of the upper side and at least one of the measuring surfaces 18, 19, 20 pass the measuring point 23, 24, 25, wherein the optical measuring device 13, 14, 15 continuously determines optical measured values ​​and a computing device 30 distinguishes between the measured values ​​which are determined at the measuring surface 18, 19, 20 and the measured values ​​which are determined at the structured regions.

[0050] A method characterized in that the area of ​​the substrate 12 is at least 100 cm 2 the structural elements 21 have a spatial extent in the range between 1 nm and 100 µm and the measuring surfaces 18, 19, 20 extend over an area of ​​at least 1 mm 2 and a maximum area of ​​1000 mm 2 extend and is smooth.

[0051] A method which is characterized in that a circular disk-shaped substrate 12 having a diameter of at least 30 cm rests concentrically to the axis of rotation D on a susceptor 4 which is driven about the axis of rotation D and which forms the floor of a process chamber 3, the ceiling of which is formed by a gas inlet element 9 which has a multiplicity of gas outlet openings 11 arranged uniformly distributed over a gas outlet surface 10, through which a process gas is fed into the process chamber 3, wherein passage openings 17 penetrate the gas outlet surface 10, through which an optical path 16 extends between the measuring point 23, 24, 25 and the optical measuring device 13, 14, 15 assigned to the measuring point 23, 24, 25.

[0052] A method which is characterized in that optical measurement values ​​are determined at a plurality of measuring surfaces 18, 19, 20, each having a different distance from a center Z of the substrate 12.

[0053] A method characterized in that the substrate 12 consists of a IV material, a III-V material or a II-VI material and / or that the structural elements 21 are regularly arranged and / or that the structural elements 21 consist of a IV material, a III-V material or a II-VI material and / or that the structural elements 21 are spaced-apart columns, wires, pyramids, depressions or two-dimensional structures or openings in a mask and / or that the structural elements 21 consist of Si, GaN or AlN.

[0054] A method characterized in that the optical measured values ​​are emission values ​​and / or reflection values.

[0055] A method which is characterized in that temperature values ​​of the substrate 12 are calculated from the emission values ​​and reflection values ​​determined at the measuring surfaces 18, 19, 20 and the temperature values ​​are used to regulate the temperature of the surface of the substrate against a desired value by means of a heating device 5 and / or that the heating device 5 has a plurality of heating zones 6, 7, 8 and each heating zone 6, 7, 8 is locally assigned a measuring point 23, 24, 25.

[0056] A method which is characterized in that a III-V layer 28, IV layer 28 or II-VI layer 28 is deposited at least on the structural elements 21 and / or that at least one layer 28 consisting of GaN, AIN, InGaN or AlGaN is deposited on the structural elements 21 and / or that the layer thickness b of a layer 28 or layer sequence 28, 29 deposited on the structural elements is less than the height a of the structural elements 21.

[0057] A method which is characterized in that a temperature is controlled with the optical measured values ​​using a heating device 5, in particular in several heating zones 6, 7, 8, wherein a first average temperature is calculated over the entire rotation of the substrate 12 taking into account all measured values ​​and a second average temperature is calculated taking into account only the temperatures measured on the measuring surface 18, 19, 20, wherein an offset is calculated by forming the difference between the second average temperature and the first average temperature and an actual temperature is formed by adding the first average value and the offset, wherein the actual value is used for the temperature control.

[0058] A substrate which is characterized in that the upper side of the substrate 12 is predominantly structured with structural elements 21 influencing the reflection and / or the emission of an unstructured surface of the substrate and has one or more measuring surfaces 18, 19, 20 at which the upper side is free of the structural elements 21 and in particular is unstructured.

[0059] A substrate characterized in that a plurality of measuring surfaces 18, 19, 20 are provided, each having a different distance from a center Z of the circular substrate 12, wherein the surface extension of each of the measuring surfaces 18, 19, 20 is at least a thousand times larger than a spatial extension of a structural element 21.

[0060] A substrate characterized in that the area of ​​the substrate 12 is at least 100 cm 2the structural elements 21 have a spatial extent in the range between 1 nm and 100 µm and the measuring surface 18, 19, 20 extends over an area of ​​at least 1 mm 2 and a maximum area of ​​1000 mm 2 extends and is smooth.

[0061] A substrate characterized in that the substrate 12 consists of a IV material, a III-V material or a II-VI material and / or that the structural elements 21 are regularly arranged and / or that the structural elements 21 consist of a IV material, a III-V material or a II-VI material and / or that the structural elements 21 are spaced-apart columns, wires, pyramids, depressions or two-dimensional structures and / or that the structural elements 21 consist of Si, GaN or AlN and / or that the structural elements 21 are openings in a mask.

[0062] A CVD reactor, characterized in that the computing device 30 is configured to carry out a method according to one of claims 1 to 9.

[0063] A CVD reactor, which is characterized in that a heating device 5 having a plurality of heating zones 6, 7, 8 is arranged below the susceptor 4 and three measuring points 23, 24, 25 are locally assigned to the heating zones 6, 7, 8 and the computing device 30 forms temperature values ​​of the substrate 12 from the optical measured values ​​and a control device of the computing device 30 regulates the temperature of the substrate 12 at the measuring points 23, 24, 25 to a desired value using the temperature values.

[0064] All disclosed features are essential to the invention (individually, but also in combination with one another). The disclosure of the application hereby fully incorporates the disclosure content of the associated / attached priority documents (copy of the prior application), also for the purpose of incorporating features of these documents into claims of the present application. The subclaims, even without the features of a referenced claim, characterize independent inventive developments of the prior art with their features, in particular for filing divisional applications based on these claims. The invention specified in each claim may additionally comprise one or more of the features provided in the above description, in particular with reference numerals, and / or specified in the list of reference numerals.The invention also relates to designs in which individual features mentioned in the above description are not implemented, in particular insofar as they are clearly unnecessary for the respective intended use or can be replaced by other technically equivalent means. List of reference symbols 1 CVD reactor 2 housings 3 Process Chamber 4 Susceptor 5 Heating device 6 outer heating zone 7 middle heating zone 8 inner heating zone 9 Gas inlet organ 10 Gas outlet area 11 Gas outlet opening 12 Substrat 13 pyrometers 14 pyrometers 15 pyrometers 16 optical path 17 Passage opening 18 measuring area 19 Measuring area 20 measuring area 21 Structural element 22 Frontal surface 23 measuring point 24 measuring points 25 measuring points 26 Surface 27 Base layer 28 shift 29 shift 30 computing device 31 supply line 32 Control device 33 Trace of measuring point 23 34 Trace of measuring point 24 35 Trace of measuring point 25 D axis of rotation Z Center a Height of the structural element b Thickness of the coating QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2018 106 481 A1

[0002] DE 10 2018 125 431 A1

[0002] DE 10 2014 109 335 A1

[0005] US 11,063,181 B2

[0006] US 11,600,538 B2

[0007]

Claims

[1] Method for depositing one or more layers (28, 29) on a substrate (12) in a housing (2) of a CVD reactor (1), during which the substrate (12) is moved about a rotational axis (D) and an optical measurement value is determined on the upper side of the moving substrate (12) by means of at least one optical measuring device (13, 14, 15) at a measuring point (23, 24, 25) which is in particular fixed to the housing, characterized by that the upper side of the substrate (12) is predominantly structured with structural elements (21), wherein the structural elements (21) influence the optical measurement value, and the surface has one or more measuring surfaces (18, 19, 20) on which the upper side is free of the structural elements (21) and in particular unstructured, wherein the optical measured value is determined on at least one of the measuring surfaces (18, 19, 20). [2] Method according to claim 1, characterized bythat the measuring point (23, 24, 25) fixed to the housing is spaced from the axis of rotation (D) and that during the movement of the substrate (12) both structured regions of the upper side and at least one of the measuring surfaces (18, 19, 20) pass the measuring point (23, 24, 25), wherein the optical measuring device (13, 14, 15) continuously determines optical measured values and a computing device (30) distinguishes between the measured values determined at the measuring surface (18, 19, 20) and the measured values determined at the structured regions. [3] Method according to one of the preceding claims, characterized by that the area of the substrate (12) is at least 100 cm 2 the structural elements (21) have a spatial extent in the range between 1 nm and 100 µm and the measuring surfaces (18, 19, 20) extend over an area of at least 1 mm 2 and a maximum area of 1000 mm 2 extend and is smooth. [4] Method according to one of the preceding claims, characterized by in that a circular disk-shaped substrate (12) having a diameter of at least 30 cm rests concentrically to the axis of rotation (D) on a susceptor (4) which is driven about the axis of rotation (D) and forms the floor of a process chamber (3), the ceiling of which is formed by a gas inlet element (9) which has a multiplicity of gas outlet openings (11) arranged uniformly distributed over a gas outlet surface (10), through which a process gas is fed into the process chamber (3), wherein passage openings (17) penetrate the gas outlet surface (10), through which passage openings an optical path (16) extends between the measuring point (23, 24, 25) and the optical measuring device (13, 14, 15) assigned to the measuring point (23, 24, 25). [5] Method according to one of the preceding claims, characterized bythat optical measurement values are determined on several measuring surfaces (18, 19, 20), each having a different distance from a center (Z) of the substrate (12). [6] Method according to one of the preceding claims, characterized by that the substrate (12) consists of a IV material, a III-V material or a II-VI material and / or that the structural elements (21) are regularly arranged and / or that the structural elements (21) consist of a IV material, a III-V material or a II-VI material and / or that the structural elements (21) are spaced-apart columns, wires, pyramids, depressions or two-dimensional structures or openings in a mask and / or that the structural elements (21) consist of Si, GaN or AIN. [7] Method according to one of the preceding claims, characterized by that the optical measured values are emission values and / or reflection values. [8] Method according to claim 6, characterized bythat temperature values of the substrate (12) are calculated from the emission values and reflection values determined on the measuring surfaces (18, 19, 20) and the temperature values are used to regulate the temperature of the surface of the substrate against a desired value by means of a heating device (5) and / or that the heating device (5) has several heating zones (6, 7, 8) and each heating zone (6, 7, 8) is locally assigned a measuring point (23, 24, 25). [9] Method according to one of the preceding claims, characterized by that a III-V layer (28), IV layer (28) or II-VI layer (28) is deposited at least on the structural elements (21) and / or that at least one layer (28) consisting of GaN, AIN, InGaN or AlGaN is deposited on the structural elements (21) and / or that the layer thickness (b) of a layer (28) or layer sequence (28, 29) deposited on the structural elements is less than the height (a) of the structural elements (21). [10] Method according to one of the preceding claims, characterized by in that a temperature is controlled in each case with the aid of a heating device (5), in particular in a plurality of heating zones (6, 7, 8), with the optical measured values being used to calculate a first mean temperature over the entire rotation of the substrate (12) taking all measured values into account, and a second mean temperature being calculated taking only the temperatures measured on the measuring surface (18, 19, 20) into account, an offset being calculated by forming the difference between the second mean temperature and the first mean temperature, and an actual temperature being formed by adding the first mean value and the offset, the actual value being used for temperature control. [11] A substrate for use in a method according to any one of the preceding claims, characterized bythat the upper side of the substrate (12) is predominantly structured with structural elements (21) influencing the reflection and / or the emission of an unstructured surface of the substrate and has one or more measuring surfaces (18, 19, 20) at which the upper side is free of the structural elements (21) and in particular is unstructured. [12] Substrate according to claim 11, characterized by that a plurality of measuring surfaces (18, 19, 20) are provided, each having a different distance from a center (Z) of the circular substrate (12), wherein the surface extension of each of the measuring surfaces (18, 19, 20) is at least a thousand times larger than a spatial extension of a structural element (21). [13] Substrate according to claim 11 or 12, characterized by that the area of the substrate (12) is at least 100 cm 2the structural elements (21) have a spatial extent in the range between 1 nm and 100 µm and the measuring surface (18, 19, 20) extends over an area of at least 1 mm 2 and a maximum area of 1000 mm 2 extends and is smooth. [14] Substrate according to one of claims 11 to 13, characterized by that the substrate (12) consists of a IV material, a III-V material or a II-VI material and / or that the structural elements (21) are regularly arranged and / or that the structural elements (21) consist of a IV material, a III-V material or a II-VI material and / or that the structural elements (21) are spaced-apart columns, wires, pyramids, depressions or two-dimensional structures and / or that the structural elements (21) consist of Si, GaN or AlN and / or that the structural elements (21) are openings in a mask. [15] CVD reactor with a process chamber (3), the bottom of which is formed by a susceptor (4) driven about a rotational axis (D) and into which a plurality of gas outlet openings (11) of a gas inlet element (9) open, which are evenly distributed over a gas outlet surface (10), for feeding a process gas into the process chamber (3), wherein an optical path (16) extends through one or more through-openings (17) between a measuring point (23, 24, 25) fixed to the housing and an optical measuring device (13, 14, 15) assigned to the measuring point (23, 24, 25), wherein an optical measured value can be measured on a surface of a substrate (12) carried by the susceptor (4) and moved during the deposition, characterized by that the computing device (30) is configured to carry out a method according to one of claims 1 to 9. [16] CVD reactor according to claim 15, characterized by in that a heating device (5) having a plurality of heating zones (6, 7, 8) is arranged below the susceptor (4) and three measuring points (23, 24, 25) are locally assigned to the heating zones (6, 7, 8) and the computing device (30) forms temperature values of the substrate (12) from the optical measured values and a control device of the computing device (30) controls the temperature of the substrate (12) at the measuring points (23, 24, 25) to a desired value using the temperature values. [17] Process, substrate or CVD reactor, characterized by one or more of the characterizing features of any of the preceding claims.

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