Method and apparatus 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). An optical measured value is determined by means of an optical measuring device (13, 14, 15) at the top side of the moving substrate at a measurement point (23, 24, 25) fixed to the housing. In order to be able to carry out this method even with structured substrates (12), according to the invention the structural elements (21) that influence the optical measured value do not extend across the entire surface of the substrate (12), but instead one or more measurement surfaces (18, 19, 20) are free of said structural elements (21), the optical measured values then being determined at least at one of said measurement surfaces (18, 19, 20). A computing device (30) can distinguish between the measured values that are determined at the measurement surfaces (18, 19, 20) and those that are determined at the structured regions of the top side of the substrate (12). The invention also relates to a substrate (12) structured in such a manner.

Description

Description Method and device for coating a structured substrate and substrate for carrying out the method 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 controlled by a heater to a target temperature. 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 106481 A1. DE 10 2018 125431 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 102014 109335 A1. The substrates to be coated are, in particular, precursors for micro-LED technology. However, structured substrates can also be used, such as HEMT or 2D. The structures can have a characteristic lateral length of 1 nm to 100 μm. The structures can be deposited in a pre-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 top side of the substrate is illuminated at the measuring point. The measuring point is fixed to the housing. Its position relative to the housing remains unchanged. Its position is opposite. the substrate is only stationary if it lies in the axis of rotation of the substrate or of the susceptor on which the at least one substrate rests. However, the optical measuring device is set up in such a way 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 lie in the axis of rotation of the susceptor. If several substrates are arranged on the susceptor or if the susceptor carries a single large substrate or if several heating zones are provided with which the susceptor is heated, it may be necessary for the measuring point to be located outside the axis of rotation or for several measuring points to be required that are at a distance from the axis of rotation, i.e. are arranged eccentrically.

[0009] The arrangement of the measuring point or measuring surface in the center of a substrate is particularly advantageous when multiple substrates are arranged on a circular arc around the rotational axis of the rotationally driven susceptor. This is the case, for example, when a gas inlet element with gas outlet openings is arranged in the center of the process chamber, generating a horizontal process gas stream flowing radially through the process chamber. The substrates can each lie on a turntable located in a pocket on the surface of the susceptor facing the process chamber. The rotational drive can be provided by a gas cushion. Every point on the substrate surface spaced from the center of the substrate moves on a cycloid during deposition. Only the center of the substrate moves on a circular arc around the rotational axis of the susceptor. This center lies on the rotational axis of the substrate.In such a configuration, the measurement is taken at a measuring point located along the rotational axis of the substrate. The measuring point is spaced from the rotational axis of the susceptor.

[0010] In another embodiment of the invention, the gas inlet element is a showerhead. The gas outlet surface of the gas inlet element forms the process chamber ceiling. A vertical gas flow emerges from the gas outlet openings and is deflected radially outward within the process chamber. In this case, a single substrate can rest on the susceptor, with the susceptor being driven in rotation about a rotational axis. However, it is also possible for multiple substrates to rest at different locations on the upper side of the susceptor facing the process chamber.

[0011] 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.

[0012] The measured values obtained when the surface is overflowing over the structured areas differ qualitatively and / or quantitatively from the measured values obtained when the surface is overflowing over the measuring areas. The optical measurement values are evaluated by a computer. The computer is programmed to distinguish between the measured values determined at the measuring surfaces and those determined at the structured areas. The computer can therefore only use those measured values determined at the measuring surfaces to calculate a temperature value or a value for the 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.

[0013] The one or more 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. d x = 2n fr x 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)).

[0014] 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. Openings are then 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 arranged in the range. different wavelengths to measure reflectivity or emissivity. A laser can be provided to illuminate the surface to measure reflectivity. The laser light is scattered more strongly in the structured areas of the upper side of the substrate than in the smooth areas near the one or more measuring surfaces. The reflectivity values measured at a structured location on the upper side of the substrate therefore differ, at least quantitatively, from the values measured at a non-structured location on the upper side of the substrate.

[0015] 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 regulate the respective heating zone in such a way that the measured temperature value is adjusted to a setpoint.

[0016] 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.

[0017] In a variant of the invention, the gas inlet element can also be arranged 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 on a cycloid, whereby the measuring point can then lie 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. However, it is advantageous if the measuring point lies in the center of the substrate or a rotatable carrier for the substrate.

[0018] The substrate used to carry out the method has a top side that is predominantly provided with structural elements. Only comparatively small surface sections are free of structural elements and have a smooth surface, wherein the surface area 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 with a measuring point moving across the substrate surface, which is illuminated in particular by a laser beam. The surface area 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 the measurement of reflectivity is required, or the area used by the pyrometer to measure 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 as this area. 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 that 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.

[0019] 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 nm. 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.

[0020] 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.

[0021] 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 , A1O 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 GaN layer in the openings. The structural elements deposited on the mask 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 the structural elements. For example, it is possible to deposit GaN transistors. In this case, 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.

[0022] 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-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.

[0023] 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. InGaN pyramids are then 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.

[0024] Nanowires made of GaN can also be deposited. The length of the nanowires can range from a few hundred nm to a few micrometers. The spacing of the nanowires can be smaller than the height of the nanowires, reaching approximately 500 nm.

[0025] 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.

[0026] The following structural elements are particularly considered: GaN columns, micro-columns (micro applications), nano-columns, 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

[0027] Embodiments of the invention are 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 of a first embodiment, 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 is a representation according to Figure 2 of a further embodiment, Fig. 6 shows section VI from Figure 5, Fig. 7 is a representation of a third embodiment according to Figure 1, Fig. 8 is a representation of a substrate according to Figure 5 for use in the reactor of the third embodiment. Description of the embodiments

[0028] The device for carrying out the method, as schematically shown in Figure 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 having a control device.

[0029] Above the heating device 5 extending in one plane, there is a susceptor 4 made of graphite, which has a pocket on its side facing away from the heating device 5, in which a substrate 12 is placed, which, for example, has a diameter of 30 cm or more. The center Z of the substrate 12 lies in the rotation axis D, about which the susceptor 4 can be rotated using a rotary drive device (not shown).

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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. With pyrometers 13, 14, and 15 Temperature values are measured. Several 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. This allows a non-emissivity-corrected temperature to be measured. However, pyrometers 13, 14, and 15 can also be two-color pyrometers.

[0034] 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.

[0035] Figure 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. 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 designate 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 of 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.

[0036] 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.

[0037] In one variant of the invention, temperature values are measured throughout the entire rotation. A mean temperature can be averaged from these temperature values. It can also be provided that an offset is formed between this mean temperature and the temperatures measured at the mean temperature at the measuring surfaces 18, 19, 20. Such an offset can be continuously redetermined. For example, each rotation can provide an offset value.

[0038] 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.

[0039] 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.

[0040] 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 be deposited in a previous process step in a different or 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.

[0041] 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.

[0042] Figure 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.

[0043] During the coating of the substrate 12, but also during a 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 around 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.

[0044] 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 has no 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.

[0045] 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.

[0046] 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 with 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, an optical measurement value is determined on an upper side of the moving substrate, wherein the upper side of the substrate 12 is predominantly structured with structural elements 21 influencing the optical measured value and has one or more measuring surfaces 18, 19, 20 on 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 measured values and a computing device 30 differentiates between the measured values which are determined on the measuring surface 18, 19, 20 and those which are determined on the structured regions.

[0047] Figures 5 and 6 show 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 ranges 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.

[0048] 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.

[0049] 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. elements. Semiconductor layers can be deposited within these openings and grow as columns 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 measuring value is measured with an optical measuring device in areas 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 value is measured with an optical measuring device, 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 4. 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.

[0050] In the embodiment shown in Figures 7 and 8, the CVD reactor 1 has a gas-tight housing 2 in which a susceptor 4 is located. The susceptor 4 is rotatable about a rotation axis 38 by means not shown. Several substrates 12 are arranged around the rotation axis 38 on the upper side of the susceptor 4 facing the process chamber 3. The substrates 12 have a circular disk shape and can rest on substrate carriers that are not shown in the drawings. The substrate carriers, in turn, are located in a pocket in the upper side of the susceptor 4 and can be driven in rotation by a gas cushion, so that the substrates 12 can rotate about a rotation axis D during the deposition of a layer.

[0051] The axis of rotation D is spaced from the axis 38 in the radial direction, relative to the axis 38.

[0052] Above the susceptor 4 is a process chamber ceiling 37. In the center of the process chamber 3 is a gas inlet element 9 for feeding a process gas into the process chamber 3. The gas inlet element 9 has a gas outlet surface 10, which in this case is formed by a cylindrical surface. This gas outlet surface 10 contains a plurality of gas outlet openings 11, which are evenly distributed over the gas outlet surface 10.

[0053] The process chamber ceiling 37 has a passage opening 17 which lies almost exactly in the axis of rotation D of the substrate 12 or the substrate carrier (not shown).

[0054] An optical path 16, which lies in the rotation axis D, runs through the passage opening 17. Using a pyrometer 13, an optical property of the surface of the substrate 12 can be determined along the optical path 16 in the manner described above.

[0055] With regard to the remaining elements of the CVD reactor 1, such as the heating device 5 with the several heating zones 6, 7, 8, the computing device 30 and the control device 32, reference is made to the above explanations.

[0056] Figure 8 shows a substrate 12 as can be used in the embodiment shown in Figure 7. The measuring surface 18, which is unstructured, is located in the center Z of the substrate 12.

[0057] The reference number 33 illustrates the track of the measuring point 23 over the surface of the substrate 12 when the latter rotates about the axis of rotation D and at the same time the susceptor 4 rotates about the axis of rotation 38.

[0058] 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:

[0059] 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 one or more measuring surfaces 18, 19, 20.

[0060] A method which is characterized 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.

[0061] A method which is characterized in that the housing-fixed measuring point 23, 24, 25 is spaced from the rotation axis D or that the substrate 12 lies on a susceptor 4 which is rotationally driven about a rotation axis 38 and the measuring point 23, 24, 25 lies in the rotation axis D.

[0062] A method characterized in that the area of the substrate 12 is at least 100 cm 2the structural elements 21 have a spatial extension in the range between 1 nm and 100 gm 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.

[0063] 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 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.

[0064] 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.

[0065] 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 AIN.

[0066] A method characterized in that the optical measured values are emission values and / or reflection values.

[0067] 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.

[0068] 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.

[0069] A method which is characterized in that a temperature is controlled with the aid of a heating device 5, in particular in several heating zones 6, 7, 8, with the optical measured values being used to control a temperature over the entire Rotation of the substrate 12, a first average temperature is calculated 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 temperature control.

[0070] 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.

[0071] 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.

[0072] A substrate characterized in that a measuring surface 18 is provided which is arranged in the center Z of the circular substrate 12, wherein the surface extension of the measuring surface 18 is at least a thousand times larger than a spatial extension of a structural element 21.

[0073] A substrate characterized in that the area of the substrate 12 is at least 100 cm 2 the structural elements 21 have a spatial Extension in the range between 1 nm and 100 gm 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.

[0074] 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 AIN and / or that the structural elements 21 are openings in a mask.

[0075] A CVD reactor, characterized in that the computing device 30 is configured to carry out a method according to one of claims 1 to 10.

[0076] 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.

[0077] All disclosed features are essential to the invention (individually, but also in combination with each other). The disclosure of the application The disclosure content of the associated / attached priority documents (copy of the prior application) is hereby incorporated in its entirety, also for the purpose of incorporating features of these documents into the 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 numbers, and / or specified in the list of reference numbers.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 27 base layer 2 housings 28 layers 3 Process chamber 29 layer 4 Susceptor 30 Calculation device 5 Heating device 31 Supply line 6 outer heating zone 32 control device 7 middle heating zone 33 trace of the measuring point 23 8 inner heating zone 34 trace of the measuring point 24 9 Gas inlet element 35 Trace of the measuring point 25 10 Gas outlet area 36 Process chamber ceiling 11 Gas outlet opening 37 Rotation axis 12 Substrat 13 pyrometers 14 Pyrometer D rotation axis 15 Pyrometer Z Center 16 optical path 17 Passage opening 18 measuring area 19 Measuring area 20 Measuring area a Height of the structural element 21 Structural element b Thickness of the coating 22 Frontal surface 23 measuring point 24 measuring points 25 measuring points 26 Surface

Claims

Claims 1. 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 an axis of rotation (D) and an optical measurement value is determined on the upper side of the moving substrate (12) using at least one optical measuring device (13, 14, 15) at a measuring point (23, 24, 25) that is in particular fixed to the housing, 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 measurement value, and the surface has one or more measurement surfaces (18, 19, 20) at which the upper side is free of the structural elements (21) and in particular is unstructured, wherein the optical measurement value is determined on at least one of the one or more measurement surfaces (18, 19, 20).

2. Method according to claim 1, characterized 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 determined at the measuring surface (18, 19, 20) and the measured values determined at the structured regions.

3. Method according to claim 1 or 2, characterized in that the housing-fixed measuring point (23, 24, 25) is spaced from the axis of rotation (D) or that the substrate (12) lies on a susceptor (4) which is driven in rotation about an axis of rotation (38) and the measuring point (23, 24, 25) lies in the axis of rotation (D).

4. Method according to one of the preceding claims, characterized in that the area of the substrate (12) is at least 100 cm 2the structural elements (21) have a spatial extension in the range between 1 nm and 100 |im 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.

5. Method according to one of the preceding claims, 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 plurality 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).

6. Method according to one of the preceding claims, characterized in that optical measurement values are determined on a plurality of measurement surfaces (18, 19, 20), each having a different distance from a center (Z) of the substrate (12).

7. Method according to one of the preceding claims, 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 AIN.

8. Method according to one of the preceding claims, characterized in that the optical measured values are emission values and / or reflection values.

9. Method according to claim 8, characterized in that 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 a plurality of heating zones (6, 7, 8) and a measuring point (23, 24, 25) is locally assigned to each heating zone (6, 7, 8).

10. Method according to one of the preceding claims, characterized in that at least on the structural elements (21) a III-V layer (28), IV layer (28) or II-VI layer (28) is deposited 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 deposited on the structural elements deposited layer (28) or layer sequence (28, 29) is less than the height (a) of the structural elements (21).

11. Method according to one of the preceding claims, characterized 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) using the optical measured values, 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.

12. Substrate for use in a method according to one of the preceding claims, 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.

13. Substrate according to claim 12, 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 the spatial extent of a structural element (21).

14. Substrate according to claim 12, characterized in that a measuring surface (18) is provided which is arranged in the center (Z) of the circular substrate (12), wherein the surface extension of the measuring surface (18) is at least a thousand times larger than a spatial extension of a structural element (21).

15. Substrate according to claim 12 to 14, characterized in that the surface 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 gm 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.

16. Substrate according to one of claims 12 to 15, 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 AIN and / or that the structural elements (21) are openings in a mask.

17. CVD reactor with a process chamber (3), the bottom of which is formed by a susceptor (4) driven about a rotation axis (D) and into which a plurality of gas outlet openings (11) of a gas inlet element (9), which are arranged uniformly distributed over a gas outlet surface (10), open into the process chamber (3) for feeding a process gas, 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 deposition using the optical measuring device (13, 14, 15) and a computing device (30), characterized in that the computing device (30) is set up to carry out a method according to one of claims 1 to 10.

18. CVD reactor according to claim 17, 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) controls the temperature of the substrate (12) at the measuring points (23, 24, 25) to a desired value using the temperature values.

19. A process, substrate or CVD reactor characterized by one or more of the characterizing features of any one of the preceding claims.

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