Observation tube incorporating curved gas connection conduits

Abstract

The invention relates to an observation tube (1) for a gas inlet element (2) adjoining a process chamber (6) of a CVD reactor with a gas outlet plate (5), comprising a body (1) designed for sealed introduction, in an installed state in the gas inlet element (2), into an arrangement of bores (47, 47', 47'') one vertically above another in delimiting walls (4, 4') that delimit at least one gas distribution chamber (3, 3') in vertical direction and the gas outlet plate (5), and having an observation channel (8) that extends along an axis from an upper end to a lower end and through which an optical path (P) can pass, wherein the gas distribution chambers (3, 3') are fluidically connected to gas connection conduits (7, 7', 7a, 7'a, 7b, 7c) that open into the process chamber (6) and at least some of the gas connection conduits (7a, 7b, 7c, 7'a) are each guided at least in sections through the body (1) along and separately from the observation channel (8).

Description

Description Observation tube with curved gas connection lines arranged therein Field of technology

[0001] The invention relates to an observation tube for a gas inlet element of a CVD reactor, wherein the gas inlet element has chambers arranged one above the other in several levels, at least one of which is a gas distribution chamber, wherein the chambers are separated from one another by boundary walls and from a process chamber by a gas outlet plate, wherein a plurality of gas connecting lines leading into gas outlet openings are arranged between the at least one gas distribution chamber and the gas outlet plate, into which gas connection lines process gases from the gas distribution chambers can be fed through gas inlet openings, wherein the observation tube is inserted into at least some boundary walls and in the gas outlet plate and has an observation channel extending along an axis from an upper end to a lower end, through which an optical path crossing the gas inlet element can pass,wherein the observation channel has a lower opening area and an upper opening area, wherein the upper opening area lies in an upper cross-sectional area of the observation channel, wherein the lower cross-sectional area lies in a projection area of the upper cross-sectional area lying in the gas outlet plate.

[0002] The invention further relates to a gas inlet device with such an observation tube.

[0003] The invention also relates to a CVD reactor with a gas inlet element having such an observation tube. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 State of the art

[0004] DE 102020112569 A1 discloses a generic device with a gas inlet element for feeding process gases into a process chamber of a CVD reactor. The gas inlet element comprises a plurality of gas distribution chambers arranged vertically one above the other between a ceiling plate and a gas outlet plate, each of which is connected to gas connecting lines leading into the gas outlet plate. The gas outlet openings are evenly distributed across the front side of the gas outlet plate facing the process chamber. Furthermore, an observation tube that can be inserted into the gas inlet element is provided. The observation tube is inserted into an insertion opening arranged in the ceiling plate and extends into the gas outlet plate. An insert tube serving as an observation channel, through which the optical path, for example of a pyrometer, runs, can be inserted into the observation tube.The observation channel is also used to feed a process gas into the process chamber. The process gas is fed laterally into the observation channel via a flow channel open to a gas distribution chamber and flows out of the observation channel into the process chamber through an opening leading into the gas outlet plate. The observation channel has sections of different diameters, with the uppermost opening cross-section being larger than the lowest opening cross-section in the gas outlet plate. The opening of the channel leading into the process chamber lies in the projection of the upper cross-sectional area of the observation tube. This regular distribution of the gas outlet openings is interrupted in the area of the front that lies within the projection of the upper cross-sectional area of the observation tube. This leads to inhomogeneities in the feed of the process gases. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 Summary of the invention

[0005] The invention is based on the object of developing a gas inlet element of a CVD reactor in a manner that is advantageous for use.

[0006] The problem is solved by the invention specified in the claims. The subclaims represent not only advantageous developments of the subordinate claims, but also independent solutions to the problem.

[0007] First and foremost, an observation tube is provided for installation in a gas inlet element of a CVD reactor comprising several gas distribution chambers arranged vertically one above the other between a ceiling plate and a gas outlet plate. The observation tube extends through these gas distribution chambers into a process chamber arranged below the gas distribution chambers. An observation channel runs through the observation tube along an axis perpendicular to the gas outlet plate, through which an optical path crossing the gas inlet element can pass. A plurality of gas connecting lines leading into the process chamber can be arranged between the gas distribution chambers and the gas outlet plate. Some of these gas connecting lines can be routed through the observation tube outside the observation channel.Through the gas connection lines, process gases from the gas distribution chambers can be fed separately into the process chamber.

[0008] In a first embodiment, the observation tube can be a one-piece cylindrical body, through whose walls the gas connection lines run. The observation tube can have an upper and a lower cross-sectional area. The upper cross-sectional area can be larger than the lower cross-sectional area. Within the observation tube, a 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 An observation channel extending along an axis perpendicular to the gas outlet plate can be arranged. The observation channel can be a bore within the observation tube. However, the observation channel can also be, for example, a tubular body inserted into the observation tube. The observation channel can have several channel sections with different diameters. Preferably, an upper channel section can have an opening area that is larger than the opening area of a lower channel section. This reduction in diameter can be realized, for example, by a step and / or a bent tube section. The upper opening area of the observation channel can lie in the upper cross-sectional area of the observation tube. The lower opening area can lie in a projection area of the upper cross-sectional area located in the gas outlet plate of the gas inlet element.The projection surface can be a surface lying in the plane of the gas outlet plate onto which the upper cross-sectional area of the observation tube is mathematically projected. The projection surface can be a surface corresponding to the upper cross-sectional area, offset along the axis of the observation channel. The projection surface can correspond to the upper cross-sectional area. The lower cross-sectional area of the observation tube is bounded radially inward by an edge of the lower opening area of the observation channel and radially outward by an edge of the projection surface. The gas connection lines guided through the wall of the observation tube can open into this lower cross-sectional area of the observation channel. The gas connection lines can open into the gas outlet plate itself and / or into opening extensions arranged on the front side of the gas outlet plate facing the process chamber.The orifices can, for example, be cylindrical bodies. However, they can also form other body shapes. The lower opening of the observation canal can end in an orifice. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15

[0009] The gas connecting lines each extend between a gas inlet and a gas outlet. The gas outlets can be located at the intersection points of imaginary grid lines that are regularly distributed across the entire front of the gas outlet plate. This regular arrangement pattern continues in the lower cross-sectional area of the observation tube. In this way, the regular distribution of the gas outlets on the front of the gas outlet plate is not interrupted in the area of the lower cross-sectional area.

[0010] In one embodiment, the gas outlet openings arranged in the outlet extensions can be located at the intersection points of imaginary grid lines extending at an angle of 60° to one another. Three outlet extensions can be located at the corners of an equilateral triangle, at the center of which lies one of the gas outlet openings arranged in the gas outlet plate itself. Within the lower cross-sectional area of the observation tube, the outlet extensions can be arranged, for example, at the corners of a regular hexagon. The opening of the observation channel can be arranged at the center of the circumcircle of this hexagon. The opening of the observation channel can be arranged in an outlet extension. The gas outlet openings opening into the gas outlet plate itself can be arranged at the corners of two regular hexagons.A first hexagon can have a smaller circumference, and a second hexagon can have a larger circumference, than the circumference of the hexagon whose corners the outlet extensions are located on. These gas outlet openings can thus have different radial spacings. The arrangement pattern of the gas outlet openings can continue across the entire surface of the gas outlet plate. In particular, the gas outlet openings can be arranged regularly across the entire front side of the gas outlet plate. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15

[0011] Some of the gas inlet openings associated with the gas outlet openings in the gas outlet plate can be arranged on a top surface of the cylindrical body of the observation tube. In particular, the gas inlet openings arranged in the top surface can be associated with the gas outlet openings arranged in the orifice extensions. The gas inlet openings can be arranged regularly around the upper opening of the observation channel. For example, the gas inlet openings can be arranged on radial planes extending at a fixed angle to one another, for example, 60°. The arrangement can, for example, correspond to the arrangement of the orifice extensions in the lower cross-sectional area of the observation tube.Thus, the gas inlet openings can be arranged on a regular hexagon whose circumference is larger than the circumference of the hexagon at whose corners the gas outlet openings located in the mouth extensions, associated with the gas inlet openings, are located. The gas inlet openings and gas outlet openings can thus be arranged radially offset from one another.

[0012] In addition, gas inlet openings can also be arranged in the outer surface of the cylindrical observation tube. For example, the gas inlet openings can be transverse bores arranged in the wall of the tube body. The gas inlet openings can be arranged regularly on the outer surface in the circumferential direction of the observation tube. The gas inlet openings can each have the same radial distance from one another to the axis of the observation channel. The gas outlet openings can be arranged at the same height or axially offset from one another in the outer surface. The gas inlet openings arranged in the outer surface can be assigned to the gas outlet openings arranged within the lower cross-sectional area of the observation tube in the gas outlet plate itself. For example, some of the gas inlet openings arranged in the outer surface can be assigned to the gas outlet openings that are on the 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 Corners of the first hexagon are arranged in the gas outlet plate itself. Other gas outlet openings can be assigned to the gas outlet openings arranged on the second hexagon in the gas outlet plate. For example, the gas inlet openings can be arranged in pairs in the circumferential direction on the lateral surface. The gas inlet openings of a pair can be arranged in different radial planes, and the respectively assigned gas outlet openings in the same radial plane. However, the gas outlet openings can also be located in radial planes that are different from those of the associated gas inlet openings.

[0013] Due to the different radial distances between the gas inlet openings and the associated gas outlet openings, the gas connection lines may be curved in sections. The gas connection lines may run obliquely to the axis of the observation channel or non-linearly, particularly at the level of the sections of the observation channel where the inner or outer diameter of the observation channel changes.

[0014] Because the cross-sectional area of the upper channel section can be larger than that of the lower channel section, the wall thickness of the observation tube wall in an upper tube section of the cylindrical body of the observation tube, in which the upper channel section is located, can be less than the wall thickness in the lower tube section, in which the lower channel section is located. Therefore, within a radial plane of the observation tube outside the observation channel, a smaller number of gas connection lines can be routed through the upper tube section than through the lower tube section. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15

[0015] The observation tube can be inserted into the gas inlet element in such a way that it forms a continuous connection between the gas distribution chambers arranged vertically one above the other and the process chamber adjacent to the gas outlet plate. The gas distribution chambers can be separated from one another by boundary plates having aligned insertion openings through which the observation tube can be inserted. The cover surface of the observation tube can lie flush in one of the boundary walls. In one embodiment, the tubular body can have at least two tube sections separated from one another by an annular collar. The annular collar can protrude circumferentially from the wall of the tubular body. The edge of the insertion opening in one of the boundary walls can form a step on which the annular collar rests. The annular collar can also lie in a pocket formed by the boundary wall.In this way, axial displacement of the observation tube within the gas inlet device can be prevented.

[0016] In addition, the annular collar can have a recess that serves, for example, as a positioning aid. For example, a projection arranged on the broad side of a boundary wall or a projection formed in the pocket of the boundary wall can engage in the recess. In this engaged position, the rotational position of the observation tube in the insertion opening can be fixed. This ensures that the observation tube lies in the insertion opening in such a way that the arrangement pattern of the gas outlet openings within the lower cross-sectional area of the observation tube fits seamlessly into the arrangement pattern of the gas outlet openings arranged on the gas outlet plate surrounding the insertion opening. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15

[0017] The observation tube can be attached to the insertion opening. The observation tube can, for example, be welded to the boundary walls. However, it can also be detachably connected to the boundary plates. Sealing elements, for example, can be used to seal the gas distribution chambers from one another in the area of the insertion openings.

[0018] The gas inlet openings of the observation tube can be connected to different gas distribution chambers in an axially offset manner. The gas inlet openings arranged in the outer surface can be connected to a first gas distribution chamber arranged above the process chamber when the observation tube is inserted into the gas inlet element. The gas outlet openings arranged in the cover surface of the observation tube can be connected to a second gas distribution chamber arranged above the first gas distribution chamber. A different process gas can be fed into the gas connecting lines via the first gas distribution chamber than via the second gas distribution chamber. For example, a process gas containing elements of main group V can preferably be fed into the process chamber via the first gas distribution chamber. A process gas containing elements of main group III can be fed via the second gas distribution chamber.It is also possible to provide only one gas distribution chamber or more than two gas distribution chambers, each containing different or the same process gases. In addition to gases containing elements from main groups III and V, other gases, such as cleaning gases, can also be fed into the process chamber.

[0019] The topmost of the several vertically arranged gas distribution chambers can be separated from the ceiling plate of the gas inlet element. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 The cover plate can have an insertion opening aligned with the upper opening of the observation tube. An insert tube can be inserted through this insertion opening into the observation tube. An upper tube section of the insert tube can run outside the gas inlet element. The insert tube can extend straight into the observation tube. The insert tube has a cavity which, when inserted, extends the observation channel running through the observation tube. The cavity can have an inner diameter that is constant over the entire length of the insert tube.

[0020] The upper opening of the insert tube can correspond to the upper opening of the observation channel. A sensor, in particular an optical sensor in the form of a pyrometer, can be arranged at or above the upper opening, with its optical path running through the observation channel. The upper opening can be significantly larger than the lower opening of the observation channel. A large upper opening allows for a large optical sensor surface, which in turn enables high measurement accuracy even at low process temperatures. The lower opening area of the observation channel, on the other hand, is selected to represent the smallest possible entry area for the optical path through the observation channel.

[0021] The outer diameter of the insert tube may be larger than the inner diameter of a central channel section of the observation channel running through the observation tube. The central channel section may have a larger inner diameter than the lower channel section adjoining the central channel section. The end face of the wall surrounding the lower opening of the insert tube may be supported on the step arranged between the channel sections or the offset channel section. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15

[0022] The insert tube can be secured to the gas inlet element in a gas-tight manner using a fastener. The fastener can be a flange secured to the outward-facing broad side surface of the cover plate of the gas inlet element by means of a seal.

[0023] A bore, particularly a transverse bore, can be arranged in a pipe section of the insert pipe, forming a flow channel. A process gas can be fed into the observation channel through the flow channel. The bore preferably connects the observation channel to the process chamber, which is closed by the ceiling plate. However, the observation channel can also be fluidly connected to another gas distribution chamber. The process gas fed into the observation channel can, for example, also be a purge gas with which the observation channel can be purged. The process gas flows through the observation channel into the process chamber.

[0024] In a further embodiment, the observation tube can have a plurality of axially spaced-apart annular plates surrounding a cladding tube in which the observation channel is arranged. The spacing between the axially spaced-apart annular plates is designed as an annular groove. The annular plates can be sealingly arranged in bores of the boundary walls. The annular plates can be sealingly connected to an edge of the bores. The cladding tube can have an opening formed by an upper end and an opening formed by a lower end. The upper opening can open into the gas distribution chamber closed by the ceiling plate. The lower opening can open into the process chamber. The cladding tube can have sections with different outer and inner diameters. In the axial direction, the annular plates can be arranged in a groove-shaped manner. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 Outside the cladding tube, several gas connection lines can be routed through the plates at a constant distance and / or in sections parallel to the outer wall of the cladding tube. The gas connection lines can be designed in sections as pipes that run obliquely or non-linearly to the axis of the observation channel. Particularly in transition areas between sections of different outer diameters of the cladding tube, the gas connection lines can be bent in sections. The gas connection lines can be designed as individual gas pipes.

[0025] The ring plates can be arranged within openings in the boundary plates that separate the gas distribution chambers. The diameter of the openings corresponds approximately to the diameter of the ring plates. The cross-sectional area of all ring plates can be the same or different. The cross-sectional area of the upper ring plate can be larger than the cross-sectional area of the lower ring plate that lies in the same plane as the gas outlet plate. The gas connecting lines routed through the ring plates open into an outlet surface that lies in the same plane as the lowest ring plate that lies in an opening in the gas outlet plate. The outlet surface lies within the projection area of the uppermost ring plate. The thickness of the ring plates can be slightly greater than the thickness of the boundary plates. The ring plates can seal the openings gas-tight.For example, sealing elements can be provided to prevent uncontrolled gas flow between the gas distribution chambers through the openings.

[0026] The gas connection lines can be routed through vertical bores arranged in the ring plates. Here, too, tolerance-related gaps between the inner wall of the bore and the outer wall of the gas pipes are sealed gas-tight, for example, using sealing elements. The sealing elements can be sealing discs or sealing rings, for example. The ring plates themselves can also be designed as sealing elements.

[0027] As in the first embodiment, an insert tube can be inserted into the observation tube. The insert tube can have sections with different outer and inner diameters. The insert tube can have an upper section with a larger outer diameter than a lower section adjoining the upper section. The lower section can extend into the cladding tube. The lower section can adjoin the upper section, forming a step. The step can rest on the other end edge of the observation tube or on the uppermost ring plate with the interposition of a sealing element, such as a sealing ring. The step can press the sealing element against the opening edge of the cladding tube in such a way that no gas can penetrate from a gas distribution chamber arranged above the cladding tube into a gas distribution chamber below.Gas flow through a tolerance-related gap between the outer wall of the lower section of the insert tube and the inner wall of the upper section of the cladding tube can also be sealed by this sealing element.

[0028] In a further embodiment of the invention, the body of the observation tube can form an annular groove extending in the circumferential direction. The annular groove can be formed by the wall of the body. The annular groove can preferably extend continuously in the circumferential direction over the wall of the body. The annular groove allows access to gas inlet openings arranged within the annular groove. The gas outlet openings 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 can be fluidly connected to the gas connecting lines running through the wall of the observation tube body. The gas connecting lines can each run parallel to the longitudinal axis of the observation tube. However, the gas connecting lines can also be bent, at least in sections. The groove can also extend only in sections in the circumferential direction, with a recess being provided only within the area of the gas inlet openings in order to enable a gas flow from the gas distribution chamber into the gas supply lines running through the wall of the observation tube.

[0029] As in the previously described embodiments, an insert tube can be inserted into the observation tube. When inserted, the insert tube can extend the observation channel formed by the observation tube by a further section. The inner diameter of the observation channel extending through the observation tube and the insert tube can change continuously in sections or over the entire length of the observation tube and the insert tube. For example, the inner diameter can increase from the observation channel of the observation tube into the observation channel section of the insert tube. The inner diameter can also increase continuously from top to bottom over the entire length of the observation channel extending through the observation tube and the insert tube. Preferably, the inner diameter increases starting from the lower or middle channel section of the observation tube.The starting point of the increasing inner diameter of the observation channel is preferably located within the horizontal plane in which the gas distribution chambers are arranged.

[0030] The insert tube may have a sealing ring at its end portion inserted into the observation tube, which seals into a circumferential groove. The 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 Sealing ring prevents gases from flowing uncontrollably from one of the gas distribution chambers through a gap arranged between the outer wall of the end section of the insert tube and the inner wall of the insertion opening of the insert tube into the observation channel.

[0031] The gas outlet openings are arranged at equal distances from one another in the circumferential direction around the observation channel, wherein the gas outlet openings are arranged in an upwardly facing end face of a collar that delimits the annular groove at the bottom.

[0032] The annular groove can preferably be arranged at the level of one of the gas distribution chambers, in particular the first gas distribution chamber, which supplies, for example, hydrides. The gases fed into the gas distribution chamber can flow through the gas inlet openings arranged in the annular groove into the gas lines running through the wall of the observation tube and into the process chamber of the CVD reactor.

[0033] The CVD reactor according to the invention can have a housing that is gas-tight to the outside. A susceptor for holding substrates can be located in the housing below the gas inlet element according to the invention with an inserted observation tube. The susceptor can be heated to a process temperature by means of a heating device arranged below the susceptor. The process chamber can be located between the gas inlet element according to the invention and the susceptor. A gas outlet element can extend annularly around the susceptor. The housing can have a housing cover that forms the cover plate of the gas inlet element, so that the gas inlet element is part of the housing cover. A cooling chamber can be arranged below the gas distribution chambers. The coolant chamber can be directly adjacent to the gas outlet plate. The gas interconnectors 31226N1PCT drg / drag 16 January 2025 Ai 2023-15 The observation tube and the cooling chamber may preferably intersect. The plurality of gas connecting lines extending outside the observation tube through the boundary walls and the gas outlet plate may be configured as small tubes.

[0034] The body of the observation tube can consist of several parts or be a single piece. The observation channel and the gas connection lines can be formed as bores in the body. The observation tube can be manufactured using a 3D printing process or spark erosion. Brief description of the drawings

[0035] Embodiments of the invention are explained below with reference to the attached drawings. They show: Fig. 1 a cross section through a CVD reactor according to the invention with a gas inlet element 2 of a first embodiment, Fig. 2 an enlarged view of the underside of the gas outlet plate 5 in direction II in Figure 1, Fig. 3 the gas inlet element 2 enlarged in detail III in Figure 1 with an observation tube 1 inserted into the boundary walls 4, 4' and the gas outlet plate 5, into which observation tube 1 an insert tube 29 is inserted, Fig. 4 the observation tube 1 according to the embodiment shown in Figures 1, 2 and 3, 31226N1PCT drg / drag January 16, 2025 Ai 2023-15Fig. 5 a section along the line VV in Figure 4, wherein the gas connection lines 7a, 7b connecting the gas distribution chamber 3 with the process chamber 6 can be seen,Fig.6 is a plan view of the front side of the observation tube 1 in direction VI in Figure 5, wherein gas inlet openings 36' connected to the gas connection lines 7'a are arranged around the upper opening 45 of the observation tube 1, Fig. 7 is a section along the line VII-VII in Figure 4, wherein the gas inlet openings 37a, 37b connected to the first gas distribution chamber 3 are arranged in the wall 35 of the observation tube 1, to which the gas connection lines 7a, 7b connect, Fig. 8 is a section along the line VIII-VIII in Figure 6, wherein the gas connection lines 7'a originating in the cover surface 1' and opening into mouth extensions 14 projecting from the observation tube 1 in the direction of the process chamber 6 are shown, Fig. Fig. 9 is a plan view of the underside of the observation tube 1 facing the process chamber 6 in the direction IX in Fig. 4, Fig. 10 is a section along the line XX in Fig. 9;11 is a perspective view of the section in Figure 10, wherein the mouth extensions 14 projecting from the base surface 1'' of the observation tube 1 can be seen, 31226N1PCT drg / drag January 16, 2025 Ai 2023-15Fig. 12 is a perspective view of a second embodiment of the observation tube 1, wherein gas inlet openings 36' and sealed drilled openings 38 connected to the gas connecting lines 7b are arranged on the cover surface 1' of the observation tube 1 around the upper opening 45,Fig. 13 is a plan view of the front side of the observation tube 1 in direction XIII in Figure 12,Fig. 14 is a section along the line XIV-XIV in Figure 13,Fig. Fig. 15 is a section along the line XV-XV in Fig. 13, Fig. 16 is a section along the line XVI-XVI in Fig. 13, Fig. 17 is a section along the line XVII-XVII in Fig. 13, Fig.18 shows a cross section through a CVD reactor according to the invention with a gas inlet element 2 of a second exemplary embodiment, Fig. 19 shows a view of the gas outlet plate 5 of the gas inlet element 2 in the direction XIX in Fig. 18, Fig. 20 shows a section along the line XX-XX in Fig. 19, 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 Fig. 21 shows a cross section through a CVD reactor according to the invention with a third exemplary embodiment of an observation tube 1 inserted into the gas inlet element 2, Fig. Fig. 22 shows a section through the body 1 of the observation tube of the third embodiment, Fig. 23 shows the observation tube 1 according to the third embodiment shown in Figs. 21 and 22, Fig. 24 shows a section along the line XXIV-XXIV in Fig. 22. Description of the embodiments.

[0036] Figure 1 shows a CVD reactor with a gas-tight housing 23 for depositing, for example, III-V layers on substrates 21. A process chamber 6 is located in the housing 23. The process chamber 6 is bounded at the top by a ceiling plate 24 and at the bottom by a susceptor 22. The susceptor 22 can be made of graphite or the like. The susceptor 22 and the process chamber 6 above it can be heated by means of a heating device 20 arranged below the susceptor 22. This can be done by heat conduction, heat radiation, or induction. The heating device 20 can be, for example, an RF coil or resistance coil. The substrates 21 are arranged on the surface of the susceptor 22 facing the ceiling plate 24 and are thermally treated in the process chamber 6, wherein in particular the III-V layers are deposited on the surface of the substrates.

[0037] A gas inlet element 2 is arranged above the process chamber 6. The gas inlet element 2 comprises several gas distribution chambers 3, 3' arranged vertically one above the other, which are separated from one another by boundary walls 4, 4'. At least one gas supply line 25, 26 opens into each of the gas distribution chambers 3, 3' in order to feed process gases into the gas distribution chambers 3, 3'. The gas inlet element 2 has a gas outlet plate 5 pointing towards the process chamber 6. A plurality of gas connecting lines 7, 7', 7a, 7b, 7'a open into this gas outlet plate 5 to the front side 46 of the gas outlet plate 5, which connect the gas distribution chambers 3, 3' with the process chamber 6.

[0038] First gas connection lines 7, 7a, 7b connected to the first gas distribution chamber 3 open into the gas outlet plate 5 itself. A first process gas, which contains, for example, hydrides of elements from main group V, is preferably fed into the first gas distribution chamber via the gas supply line 25. A second gas distribution chamber 3' is arranged above the first gas distribution chamber 3 and is delimited at the top by the ceiling plate 24. A second process gas can be fed into the second gas distribution chamber 3' via a gas supply line 26. Second gas connection lines 7', 7'a are connected to the second gas distribution chamber 3' and open into outlet extensions 14 projecting from the front side 46 of the gas outlet plate 5. The second process gas preferably contains organometallic compounds of elements from main group III.The first and second process gases are fed into the process chamber 6 together with a carrier gas, for example hydrogen or nitrogen.

[0039] Extending rearward of the gas outlet plate 5 is a cooling chamber 17 into which a coolant can be fed via a coolant inlet 18. The coolant can exit the cooling chamber 17 again through the coolant outlet 19. The cooling chamber 17 is separated from the gas distribution chamber 3 by the boundary wall 4'. The gas connecting lines 7, 7a, 7b, 7', 7'a cross the cooling chamber 17. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15

[0040] Figure 2 shows a section of the front side 46 of the gas outlet plate 5. Gas outlet openings 15, 15', 56, 56a, 56b adjoining the gas connection lines 7, 7a, 7b, 7', 7'a are arranged regularly over the entire surface of the gas outlet plate 5. The first gas connection lines 7, 7a, 7b connected to the first gas distribution chamber 3 open into first gas outlet openings 56, 56a, 56b arranged directly in the gas outlet plate 5. The second gas connection lines 15, 15' connected to the second gas distribution chamber 3' open into gas outlet openings 15, 15' arranged on the front side of the outlet extensions 14.

[0041] The gas outlet openings 15, 15' extend at the intersection points of imaginary grid lines that extend at an angle of 60° on the front side 46. The gas outlet openings 15, 15' are each located at the corners of an equilateral triangle. A gas outlet opening 56a, 56b is arranged at the intersection point of the perpendicular bisectors of the equilateral triangle, which also serve as the angle bisectors. However, the gas outlet openings 15, 15', 56, 56a, 56b can also be arranged according to a different arrangement pattern. According to the invention, an observation channel 8 extending through an observation tube 1 opens where, in the arrangement pattern shown in Figure 2, a gas outlet opening 15, 15' would have to be arranged along one of the grid lines connecting the gas outlet openings 15, 15'.A plurality of gas outlet openings 15' are regularly arranged immediately around the edge 48 delimiting the lower opening 28 of the observation channel 8.

[0042] As shown in Figure 3, the observation tube 1 extends parallel to the gas connecting lines 7, 7a, 7b, 7', 7'a through bores 47, 47', 47'' in the boundary walls 4, 4' and the gas outlet plate 5.31226N1PCT drg / drag 16 January 2025 Ai 2023-15 In the embodiment shown in Figures 1 to 17, the observation tube 1 is a one-piece cylindrical body. The cover surface 1' is flush with the broad side surface of the boundary wall 4 facing the cover plate 24. The base surface 1'' is flush with the gas outlet plate 5.

[0043] An optional annular collar 16 is arranged circumferentially on the wall 35 of the observation tube 1, dividing the observation tube 1 into two tube sections. The annular collar 16 is connected to the wall 35. The annular collar 16 rests on an edge region surrounding the opening 47' of the broad side surface of the boundary wall 4' facing the ceiling plate 24, which separates the second gas distribution chamber 3 from the coolant chamber 17. The annular collar 16 can be designed as a sealing ring that seals the bore 47'. The annular collar 16 can have a recess 57 (see Figure 12), which serves as a positioning aid. A projection (not shown) arranged on the broad side surface of the boundary wall 4' facing the ceiling plate 24 can engage in the recess. In this way, the rotational position of the observation tube is defined.The annular collar 16 can also have several recesses spaced apart at a fixed angle, each of which engages a projection. For example, a sealing ring (not shown) can be interposed between the annular collar 16 and the boundary wall 4'.

[0044] The observation tube 1 has an upper cross-sectional area 11 and a lower cross-sectional area 12. The observation channel 8 extends through the observation tube 1 along an axis running perpendicular to the gas outlet plate 5. The observation channel 8 opens into an orifice extension 14 and has several channel sections 30, 31, 32 with different diameters. An upper channel section 32 has an upper opening area 10 which is larger than the cross-sectional area 9 of the lower channel section 30. The upper opening area 10 of the observation channel 1 lies in the upper cross-sectional area 11 of the observation tube 1. The lower opening area 9 of the observation channel 8 lies in a projection area 13 of the upper cross-sectional area 11 of the observation tube 1, said projection area being located in the gas outlet plate 5.In the embodiment shown in Figure 3, the lower cross-sectional area 12 of the observation tube 1 corresponds to the upper cross-sectional area 11. The lower cross-sectional area 12 is bounded radially inward by the edge 48 of the lower opening area 9 of the observation channel 8 and radially outward by the edge 49 of the projection area 13 (see Figure 2). The projection area is a surface congruent with the upper cross-sectional area 11 in the plane of the gas outlet plate.

[0045] According to the invention, several gas outlet openings 15', 56a, 56b are located in the lower cross-sectional area 12. The gas connecting lines 7a, 7b, 7'a opening into these gas outlet openings 15', 56a, 56b are guided through the wall 35 of the observation tube 1. The second gas connecting lines 7'a connected to the second gas distribution chamber 3' originate in the cover surface 1' of the observation tube 1. The associated second gas inlet openings 36' are arranged around the upper opening 45 of the observation channel 8 on the cover surface 1'. The second gas inlet openings 36' are each arranged in radial planes extending at an angle of 60° to one another and at a constant radial distance from the axis of the observation channel 8. Through the second gas inlet openings 36', the second process gas can flow from the second gas distribution chamber 3' through the second gas connection lines 7'a into the process chamber 6.The second gas outlet openings 15' assigned to the second gas inlet openings 36' are each arranged in a radial plane with the respective second gas inlet opening 36'.31226N1PCT drg / drag January 16, 2025 Ai 2023-15.

[0046] First gas inlet openings 37a, 37b, connected to the first gas connecting lines 7a, 7b, through which the first process gas flows from the first gas distribution chamber 3 into the first gas connecting lines 7a, 7b, are arranged laterally in the wall 45 of the observation tube 1 (see Figure 4).

[0047] As shown in Figure 4, the first gas inlet openings 37a, 37b are arranged in pairs in the wall 45 of the observation tube 1 above the annular collar 16. The gas inlet openings 37a, 37b lie in different radial planes. However, the gas outlet openings 56a, 56b associated with the gas inlet openings 37a, 37b lie in the same radial plane, but have different radial distances from the axis of the observation channel 8.

[0048] The gas outlet openings 15', 56a, 56b are offset radially inward from the respective associated gas inlet openings 36', 37a, 37b. To compensate for this radial offset, the gas connecting lines 7a, 7b, 7'a connecting the gas inlet openings 36', 37a, 37b with the gas outlet openings 15', 56a, 56b are bent in sections.

[0049] In the embodiment of the observation tube 1 shown in Figure 3, the upper channel section 32 has a larger diameter than the middle channel section 31, which in turn has a larger diameter than the lower channel section 30. The diameter reduction is achieved by a bent channel section 53, 53'. Due to the diameter reduction of the observation channel 8, the wall thickness of the observation tube 1 is smaller in the area of the upper channel section 32 than in the area of the middle channel section 31 and the lower channel section 30. Therefore, it is possible to have two 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 first gas connection lines 7a, 7b are to be guided in a radial plane through the wall 35 of the observation tube 1. In the region of the upper channel section 32, however, only a second gas connection line 7'a runs within a radial plane through the wall 35.

[0050] The first gas connection lines 7b and the second gas connection lines 7'a run essentially parallel to the contour of the observation channel 8. At the level of the bent channel sections 35, 35', these gas connection lines 7b, 7'a are bent radially inward or radially outward in sections. The first gas connection lines 7a, on the other hand, run parallel to the first and second gas connection lines 7, 7' arranged outside the observation tube 1 over their entire length.

[0051] An insert tube 29 is inserted into the observation tube 1. For this purpose, the cover plate 24 has an insertion opening 45 that is aligned with the bores 47, 47', 47''. A lower section of the insert tube 29 can be inserted through the insertion opening 45. The lower section of the insert tube 29 extends linearly into the upper tube section of the observation tube 1. The upper end of the insert tube 29 protrudes beyond the cover plate 24 of the gas inlet element 2. Due to the linear extension of the insert tube 29, the optical path can run through the insert tube 29. The upper section forms an upper opening 27, which simultaneously also represents the upper opening of the observation channel 8, 8'. The cavity of the insert tube 29 therefore extends the observation channel 8 running through the observation tube 1 by a second section 8' beyond the cover plate 25 of the gas inlet element 2.A pyrometer or similar device can be connected to the upper opening 27. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15.

[0052] The upper section of the insert tube 29 is adjoined by a flange 34, with which the insert tube 29 can be fastened to the outside of the ceiling plate 24. This is done with the interposition of a sealing ring 39. In this way, the insertion opening 45 is sealed so that no process gas can escape from the second gas distribution chamber 3' through the insertion opening 45 from the gas inlet element 2 through the ceiling plate 24.

[0053] The upper section of the insert tube 29 furthermore has a transverse bore 43 forming a flow channel through which the second process gas can flow from the second gas distribution chamber 3' into the observation channel 8, 8'.

[0054] The inner diameter 51 of the insert tube 29 and thus the diameter of the second section 8' of the observation channel 8 is smaller than the diameter of the upper opening surface 10 of the observation channel 8 and larger than the inner diameter of the middle channel section 31. The lower opening 44 of the insert tube 29 is aligned with the upper opening 27. In the embodiment shown in Figure 3, the upper opening 27 and the lower opening 44 have the same opening area. The peripheral edge 52 of the insert tube 29 surrounding the lower opening 44 is supported on an inclined flank 50 formed by a bent channel section 53. This bent channel section 53 is located at the level of the first gas distribution chamber. mer 3.

[0055] Figure 4 shows the first process gas inlets 37a, 37b arranged in pairs along the circumferential direction of the wall 35. The distance between the process gas inlets 37a, 37b is smaller than the distance between the pairs. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15

[0056] As shown in Figure 5, the first gas inlet opening 37a is arranged only slightly radially offset from its associated gas outlet opening 56a. Therefore, the first gas connection line 7a connecting the first gas inlet opening 37a to the first gas outlet opening 56a extends substantially parallel to the axis of the observation channel 8. The gas connection line 7a is bent vertically downwards from the gas inlet opening 37a toward the base area 1'' of the observation tube 1.

[0057] The first gas connection line 7b connected to the other first gas inlet opening 37b of the pair extends in sections obliquely to the axis of the observation channel 8, since the first gas outlet opening 56b is displaced radially inward relative to the first gas inlet opening 37b assigned to it and is arranged in a different radial plane (see also Figure 7).

[0058] Figure 6 shows a top view of the top surface 1' of the observation tube 1. The second gas inlet openings 6' are arranged at equal distances from one another on an edge surface surrounding the upper opening of the observation tube 1. The second gas inlet openings 6' are arranged at an angle of 60° to one another in radial planes. This arrangement corresponds to the arrangement of the associated gas outlet openings 15' shown in Figure 2, with the second gas outlet openings 15' being displaced radially inward relative to the second gas inlet openings 36' within the respective radial plane.

[0059] As shown in Figure 7, the first gas connection line 7b extends from the second gas inlet opening 37b into a first section horizontal to the axis of the observation channel 8. At this first section 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 As can be seen in Figure 5, a second section runs parallel to the axis of the observation channel 8. Approximately at the level of the bent channel section 53', a third section extends obliquely to the axis of the observation channel 8 and is bent in the direction of the observation channel 8. This third section merges into a fourth section, which again runs parallel to the axis of the observation channel 8 and opens into the gas outlet opening 56b.

[0060] Figure 8 shows the second gas connecting lines 7'a running in the wall 35 of the observation tube 1, which originate from the second gas inlet openings 36' arranged in the cover surface 1' of the observation tube 1 and open into the corresponding gas outlet openings 15' in the orifice extensions 14. The gas outlet openings 15' are offset radially inward relative to the gas inlet openings 36'. This offset is compensated for by a radially inwardly bent section of the second gas connecting lines 7'a at the level of the bent section 53 of the observation channel 8.

[0061] Figure 9 shows the gas outlet surface of the observation tube 1. The gas outlet openings 15', 56a, 56b extend evenly spaced from one another outside the lower opening 28 of the observation channel 8 in the lower cross-sectional area 12 of the observation tube 1. The first gas outlet openings 56a, the first gas outlet openings 56b, and the second gas outlet openings 15' each lie on the corner points of an imaginary hexagon around the opening 28. The circumference of the hexagon formed by the second gas outlet openings 15' is larger than the circumference of the hexagon formed by the first gas outlet openings 56b and smaller than the circumference of the hexagon formed by the first gas outlet openings 56a. The gas outlet openings 15' are located at the center points of the base areas of the 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 cylindrical mouth extensions 14. The area of the gas outlet openings 15', 56a, 56b is essentially the same size. However, the area of the first gas outlet openings 56a, 56b and that of the second gas outlet openings 15' can also be different. The number of first gas outlet openings 56a, 56b within the lower cross-sectional area 12 of the observation tube 1 is twice as large as the number of second gas outlet openings 15'. On the entire area of the gas outlet plate 5, the ratio of second gas outlet openings 56a, 56b to first gas outlet openings 15, 15' is 2 : 1.

[0062] As can be seen in Figures 10 and 11, the first gas outlet openings 56a, 56b are flush with the surface of the gas outlet plate 5. The second gas outlet openings 15', however, are spaced apart from the gas outlet plate 5 due to their arrangement in the front side of the orifice extensions 14. As a result, mixing of the process gases only occurs below the gas outlet plate 5 in the region of the plane of the gas outlet openings 15'.

[0063] The gas connection lines 7a, 7b, 7'a can be bores passing through the wall 35 of the observation tube 1 or tubes inserted into the wall 35.

[0064] Figure 12 shows a further embodiment of an observation tube 1. For manufacturing reasons, it is necessary to drill the individual line sections separately during the manufacture of the gas connecting lines 7b, 7'a, which run partially obliquely to the axis of the observation channel 8. The line sections running parallel to the axis of the observation channel 8 are realized by a bore in the cover surface 1' of the observation tube 1, and the line sections running obliquely to the axis of the observation channel 8 are realized by bores in the wall 35 of the observation tube 1. The resulting drilled openings 38, which do not function as process gas inlets 36', 37a, 37b, are sealed. The first two gas inlet openings 37a, 37b and the sealed bore 38' are arranged as a group of three in the wall 35 of the observation tube 1 at the level of the middle channel section 31.

[0065] As can also be seen in Figure 12, the annular collar 16 surrounding the observation tube 1 in the circumferential direction can be open.

[0066] In the cover surface 1' of the observation tube 1, a second gas inlet opening 36' and a sealed bore opening 38 connected to the first gas connection line 7b are arranged in pairs (see also Figure 13). As shown in Figure 13, the obliquely running line sections of the first gas connection line 7b extend within a plane perpendicular to the cover surface 1'. The obliquely running line section of the second gas connection line 7'a also extends perpendicular to the cover surface 1', but at an angle offset from this plane.

[0067] Figure 14 shows an example of the cross-section of a first gas connection line 7b and a second gas connection line 7'a. The line section of the second gas connection line 7'a, which runs obliquely to the axis of the observation channel 8 at the level of the central channel section 31, has a sealed bore 38' in the wall 35 of the observation tube 1. The seal prevents the process gas from flowing from the first gas distribution chamber 3 into the second gas connection line 7'a, thus preventing premature mixing of the process gases within the gas connection lines (see also Figures 16 and 17). 31226N1PCT drg / drag January 16, 2025 Ai 2023-15

[0068] The first gas connecting lines 7b, which open into the first gas outlet openings 56b, have a sealed bore opening 38 in the end face of the observation tube 1 and a sealed bore opening 38'' in the wall 35 of the observation tube at the level of the lower channel section 30 (see Figures 14 and 17). These prevent, on the one hand, the entry of process gas from the second gas distribution chamber 3' into the first gas connecting lines 7b and, on the other hand, the entry of coolant from the coolant chamber 17 into the first gas connecting lines 7b.

[0069] In Figure 15, the gas connecting lines 7a opening into the first gas outlet openings 56a are connected to a first gas inlet opening 37a in the outer surface of the observation tube 1, through which the process gas can flow from the first gas distribution chamber 3 into the process chamber 6.

[0070] Figure 18 shows a gas inlet element 2 with a third embodiment of the observation tube 1. Two gas distribution chambers 3, 3' are provided, each of which, via associated gas connection lines 7, 7a, 7b, 7', 7'a, is in flow communication with the gas outlet plate 5. The openings 15, 15', 56a, 56b of the gas connection lines 7, 7a, 7b, 7', 7'a in the gas outlet plate 5 are arranged alternately across the cross-sectional area of the gas inlet element 2, as shown in Figure 19. The gas outlet openings 15, 15', 56a, 56b each extend at a uniform distance from one another on imaginary grid lines running at an angle of 90° to one another on the gas outlet surface 54 facing the process chamber 6.According to the invention, the lower opening 28 of a viewing tube 1 extending through a cladding tube 40 of the observation tube 1 opens at an intersection point of an imaginary grid line running through the gas outlet openings 15, 15' and an imaginary grid line running through the gas outlet openings 56, 56b. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15. the observation channel 8. The cladding tube 40 extends parallel and of the same length to the second gas connection lines 7'. The upper opening of the cladding tube 40 opens into the second gas distribution chamber 3'.

[0071] As shown in Figure 20, the observation tube 1 has a plurality of axially spaced-apart annular plates 41, 41', 41'' surrounding the cladding tube 40. Adjacent annular plates 41, 41', 41'' are spaced apart from one another by a spacing gap formed as an annular groove 58. Gas inlet openings (37b) are arranged in the annular groove 58 and are connected to some of the gas connecting lines 7b guided through the annular plates 41, 41', 41''. The annular plates 41, 41', 41'' each lie sealingly in bores 47, 47', 47'' of the boundary walls 4, 4' and the gas outlet plate 5, respectively. In the embodiment shown in Figure 20, the annular plates 41, 41', 41'' have the same cross-sectional area, so that the projection area 13 of the upper cross-sectional area 11 of the observation tube 1 coincides with the lower cross-sectional area 12 of the observation tube 1. However, the annular plates 41, 41', 41'' can also have different cross-sectional areas.For example, the upper annular plate 41 can have a larger cross-sectional area than the lower annular plate 41''. The thickness of the annular plates 41, 41', 41'' can be greater than the thickness of the boundary walls 4, 4' and / or the gas outlet plate 5. According to the invention, some of the gas connection lines 7b, 7'a are routed outside the cladding tube 40 through the annular plates 41, 41', 41''. The gas connection lines 7b, 7'a are designed as tubes that lie sealingly in bores of the annular plates 41, 41', 41''. The gas inlet openings 36', 37b connected to the gas connection lines 7b, 7'a are arranged offset from their respective associated gas outlet openings 15', 56b'. The gas outlet openings 15', 56b are offset radially inward relative to the gas inlet openings 36', 37b. As a result, the gas connecting lines 7b, 7'a are bent in sections.In the embodiment shown in Figure 20, the gas connecting lines 7b, 7'a run at the level of the bent channel section 53' at an angle to the axis of the observation channel 8. The gas connecting lines 7, 7' routed outside the observation tube 1 run parallel to the axis of the observation channel 8.

[0072] The cover plate 24 has an insertion opening 45 into which an insert tube 29 is inserted, the lower end of which is inserted into the cladding tube 40. The cavity 8' of the insert tube 29 forms an extension of the observation channel 8 extending through the observation tube 1. The lower opening area 9 of the observation channel 8 is smaller than the upper opening area 10 of the observation channel 8.

[0073] The insert tube 29 has an upper insert tube section that has a larger outer diameter and inner diameter 51 than the lower insert tube section. The lower insert tube section borders the upper insert tube section, forming a step 42, and extends straight into the cladding tube 40. The lower opening 44 of the insert tube 29 is located approximately at the level of the first gas distribution chamber 3. The lower insert tube section can also be longer and, for example, extend over the entire length of the cladding tube 40. The outer contour of the insert tube 29 can be adapted to the inner contour of the cladding tube 40.

[0074] The step 42 forms a sealing surface, which is adjacent to a first broad side surface of a sealing ring 39. The other broad side surface of the sealing ring 39 rests on the upper opening of the observation tube 1, with the interposition of a sealing ring 39, on the broad side surface of the boundary wall 4 facing the ceiling plate 24. This sealing ring 39 seals an intermediate space 55 that extends between the inner wall of the cladding tube 40 and the outer wall of the lower insert tube section. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15

[0075] As in the embodiment shown in Figure 3, the insert pipe 29 in Figure 20 is fastened to the outside of the ceiling plate 24 by means of a flange 34 with a sealing ring 33 interposed.

[0076] Figures 21 to 24 show a third embodiment of the observation tube 1. The body 1 of the observation tube is essentially cylindrical and, when installed in the gas inlet element 2, extends vertically from an upper gas distribution chamber 3' to the gas outlet plate 5. The body 1 lies sealingly in bores 47, 47', 47'' of the boundary walls that delimit the gas distribution chambers 3, 3' at the bottom and the gas outlet plate 5. For example, the body 1 can be welded to the boundary walls 4, 4' or the gas outlet plate after being inserted into the bores 47, 47', 47''.

[0077] As in the previously described embodiments, the ceiling plate 24 has an insertion opening 45 into which an insert tube 29 is inserted, the lower end of which is inserted into the body 1 of the observation tube. The lower end section of the insert tube 29 forms an annular groove in which a sealing ring 59 is located, which seals the sealing surface between the outer wall of the lower end section of the insert tube 29 and the inner wall of the insertion cavity of the observation tube 1 in a gas-tight manner. The insert tube 29 is fastened to the ceiling plate 24, for example, by means of a flange 34.

[0078] The cavity of the insert tube 29 extends the observation channel 8 running through the body 1 by a second section 8'. The inner diameter of the observation channel 8, 8' increases continuously from a central section 31 of the observation channel 8 into the insert tube 29 or up to an upper end of the insert tube. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 res 29. The inner diameter of the observation channel 8 of the observation tube 1 at an upper end section of the middle channel section 31 corresponds to the inner diameter of the observation channel 8' of the insert tube 29 at the lower end section of the insert tube 29. The starting point of the continuous enlargement of the inner diameter of the observation channel 8, 8' extending through the observation tube body 1 and the insert tube can also lie within the first channel section 30 of the observation tube 1.

[0079] A purge gas can be fed into the observation channel 8, 8' via a bore 43 extending horizontally through the wall of the insert tube 29. The sealing ring 59 located in an annular groove in the wall of the insert tube 29 prevents unwanted purge gas flows into the second gas distribution chamber 3'.

[0080] The inner diameter of the insertion cavity for the insert tube 29 formed by an upper channel section 32 of the observation tube 1 is essentially constant over the entire length of the upper channel section 31 of the body 1. The inner diameter of the upper channel section 32 is larger than the inner diameter of the middle channel section 31. The upper channel section 32 and the middle channel section 31 of the observation channel 8 adjoin one another, forming a step. The lower end of the insert tube 29 can rest on the step.

[0081] The wall 35 of the body 1 of the observation tube forms a circumferentially extending annular groove 58. The annular groove 58 allows the inflow of gases from the first gas distribution chamber 3 into gas inlet openings 37c arranged within the wall 35 or annular groove 58, respectively, which are connected to gas connecting lines 7c extending through the wall 35. The gas connecting lines 7c are connected by the 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 Wall 35 of the body 1 and open into gas outlet openings 56c arranged in the gas outlet plate 5. The gas connection lines 7c guided through the body 1 run straight and parallel to the longitudinal axis of the body 1. However, the gas connection lines 7c can also be bent in sections, as in the previously described embodiments.

[0082] Both the outer wall of the insert tube 29 and the outer wall of the observation tube 1 have sections with different outer diameters. However, the outer diameter of the insert tube 29 can also be essentially constant over the entire length of the insert tube 29, as shown in Figure 3.

[0083] 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:

[0084] An observation tube characterized in that at least some of the gas connecting lines 7a, 7b, 7c, 7'a are each guided at least partially along the observation channel 8 and separately therefrom through the body 1.

[0085] An observation tube characterized in that the observation tube 1 is a one-piece body extending along the axis of the observation channel 8, which has a wall 35 in which at least some of the gas connection lines 7a, 7'a, 7b, 7c are arranged. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15

[0086] An observation tube characterized in that the wall 35 of the body 1 forms a circumferentially extending annular groove 58 in which gas inlet openings 37b, 37c connected to the gas connection lines 7b, 7c extending through the wall 35 are arranged.

[0087] An observation tube characterized in that the gas connection lines 7c guided through the wall 35 of the body 1 run straight and parallel to the longitudinal axis of the body 1.

[0088] An observation tube, which is characterized in that an insert tube 29 is inserted into the body 1, the cavity of which extends the observation channel 8 running through the body 1 by a second section 8', wherein the inner diameter of the observation channel 8, 8' changes continuously at least in sections over the length of the body 1 and the insert tube 29.

[0089] An observation tube characterized in that the observation channel 8 and the gas connection lines 7a, 7'a, 7b, 7c are formed by bores in the body 1 of the observation tube.

[0090] An observation tube characterized in that the upper opening area 10 of the observation channel 8 is larger than the lower opening area 9.

[0091] An observation tube characterized in that some of the gas inlet openings 36' are arranged in a cover surface 1' of the body 1, and the gas outlet openings 15' associated with these gas inlet openings 36' are arranged in a base surface 1'' of the body 1, and / or some of the gas inlet openings 37a, 37b are arranged in the wall 35 of the body 1. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15

[0092] An observation tube characterized in that the gas outlet openings 15', 56a, 56b arranged in the lower cross-sectional area 12 of the observation tube 1 are arranged radially offset from the gas inlet openings 36', 37a, 37b assigned to them.

[0093] An observation tube characterized in that some gas inlet openings 36', 37a are located in the same radial plane as the gas outlet openings 15', 56a associated with them and some gas inlet openings 37b are arranged in different radial planes than the gas outlet openings 56b associated with them.

[0094] An observation tube characterized in that some of the gas connecting lines 7a, 7b, 7'a opening into the lower cross-sectional area 12 of the observation tube 1 are bent in sections.

[0095] An observation tube characterized by one or more tube sections, wherein at least two tube sections are separated by an annular collar 16 extending in the circumferential direction and defining the position of the observation tube 1 within the gas inlet element 2.

[0096] An observation tube characterized in that the body 1 of the observation tube is manufactured by a 3D printing process or spark erosion.

[0097] An observation tube, characterized in that the body 1 is formed by axially spaced-apart annular plates 41, 41', 41'' surrounding the observation channel 8, wherein some gas connecting lines 7a, 7b, 7'a are guided outside the observation channel 8 through the annular plates 41, 41', 41'' and open into the lower cross-sectional area 12 of the observation tube 1.

[0098] An observation tube characterized in that the ring plates 41, 41', 41'' have the same diameter among themselves or that the diameters of the ring plates 41, 41', 41'' increase gradually starting from the gas outlet plate 5.

[0099] A gas inlet element 2, which is characterized in that in a lower cross-sectional area 12 of the observation tube 1, which is delimited radially inwardly by an edge 48 of the lower opening area 9 and radially outwardly by an edge 49 of the projection area 13, at least some of the gas connecting lines 7a, 7b, 7'a open into the process chamber 6.

[0100] A gas inlet element, which is characterized in that the gas connecting lines 7a, 7b, 7'a are designed as pipes arranged at least in sections outside the body 1.

[0101] A gas inlet element, which is characterized in that gas inlet openings 36, 36', 37, 37a, 37b arranged axially offset from one another are connected to different ones of the gas distribution chambers 3, 3'.

[0102] A CVD reactor with a gas inlet element 2 and a gas-tight housing 23, a susceptor 22 arranged in the housing 23 in a process chamber 6 for receiving substrates 21, and a heating device 20 controlled by a control device for tempering the substrates 21 received by the susceptor 22. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15

[0103] 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 characterize, even without the features of a referenced claim, with their features, independent inventive developments of the prior art, 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 indicated in the above description, in particular those provided with reference numbers and / or indicated 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 dispensable for the respective intended use or can be replaced by other technically equivalent means. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15. List of reference symbols 1 Observation tube, body 19 Coolant outlet 1' Cover surface 20 Heating device 1'' Base surface 21 Substrate 2 Gas inlet element 22 Susceptor 3 First gas distribution chamber 23 Housing 3' Second gas distribution chamber 24 Cover plate 4 Boundary wall 25 Gas inlet line 4' Boundary wall 26 Gas inlet line 5 Gas outlet plate 27 Upper opening 6 Process chamber 28 Lower opening 7 Gas connection line 29 Insert tube 7' Gas connection line 30 Lower channel section 7a Gas connection line 31 Middle channel section 7b Gas connection line 32 Upper channel section 7c Gas connection line 33 Sealing ring 7'a Gas connection line 34 Flange 8 Observation channel 35 Wall 9 Lower opening surface 36 Gas inlet opening 10 Upper opening surface 36' Gas inlet opening 11 Upper cross-sectional area 37 Gas inlet opening 12 Lower cross-sectional area 37a Gas inlet opening 13 Projection surface 37b Gas inlet opening 14 Mouth extension 37c Gas inlet opening 15 Gas outlet opening 38 Sealed holes 15'Gas outlet opening 38' sealed bores 16 Annular collar 38'' sealed bores 17 Cooling chamber 39 Sealing ring 18 Coolant inlet 40 Cladding tube 31226N1PCT drg / drag January 16, 2025 Ai 2023-1541 Annular plate 41' Annular plate 41'' Annular plate 42 Stufe 43 Hole44 Lower opening, insert tube45 Insert opening46 Front side47 Holes47' Holes47'' Holes 48 Rand 49 Rand 50 Bevel flank 51 Inner diameter of insert tube 52 Edge 53 Cranked channel section 53' Cranked channel section 54 Outer diameter of insert tube 55 Intermediate space 56 Gas outlet opening 56a Gas outlet opening 56b Gas outlet opening 56c Gas outlet opening 57 Recess 58 Annular groove P Optical path 31226N1PCT drg / drag 16 January 2025 Ai 2023-15

Claims

Claims 1. Beobachtungsrohr für ein mit einer Gasaustrittplatte (5) an eine Prozess- kammer (6) eines CVD-Reaktors angrenzendes Gaseinlassorgan (2), mit ei- a body (1) which is designed in such a way that, when installed in the gas inlet element (2), it sealingly engages in vertically superimposed bores (47, 47', 47'') of at least one gas distribution chamber er (3, 3‘) in Vertikalrichtung begrenzenden Begrenzungswänden (4, 4‘) and the gas outlet plate (5), and which has an observation channel (8) extending along an axis from an upper end to a lower end, through which an optical path (P) can pass, wherein the gas distribution chambers (3, 3') are fluidly connected to gas connecting lines (7, 7', 7a, 7'a, 7b, 7c) opening into the process chamber (6), characterized in that at least some of the gas connecting lines (7a, 7b, 7c, 7'a) are each guided at least in sections along the observation channel (8) and separately therefrom through the body (1).

2. Beobachtungsrohr nach Anspruch 1, dadurch gekennzeichnet, dass das Observation tube (1) along the axis of the observation channel als (8) erstreckender einteiliger Körper ist, der eine Wandung (35) auf-in which at least some of the gas connecting lines (7a, 7'a, 7b, 7c) are arranged.

3. Beobachtungsrohr nach Anspruch 2, dadurch gekennzeichnet, dass die Wall (35) of the body (1) forms a circumferentially extending annular groove (58) in which the gas inlet opening connected to the gas connection lines (7b, 7c) extending through the wall (35) en (37b, 37c) angeordnet sind. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 4. Beobachtungsrohr nach Anspruch 3, dadurch gekennzeichnet, dass die the gas connection lines (7c) guided through the wall (35) of the body (1) run straight and parallel to the longitudinal axis of the body (1).

5. Beobachtungsrohr nach einem der vorhergehenden Ansprüche, dadurch characterized in that an insert tube (29) is inserted into the body (1), the cavity of which extends the observation channel (8) running through the body (1) by a second section (8'), wherein the inner diameter of the observation channel (8, 8') changes continuously at least in sections over the length of the body (1) and the insert tube (29).

6. Beobachtungsrohr nach einem der vorhergehenden Ansprüche, dadurch characterized in that the observation channel (8) and the gas connection leitungen (7a, 7’a, 7b, 7c) von Bohrungen in dem Körper (1) des Beobach- tion pipe.

7. Beobachtungsrohr nach einem der vorhergehenden Ansprüche, dadurch characterized in that the upper opening area (10) of the observation channel (8) is larger than the lower opening area (9).

8. Beobachtungsrohr nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass in die Gasverbindungsleitungen (7a, 7’a, 7b, 7c) through gas inlet openings (36, 36', 37, 37a, 37b, 37c) process gases from the en Gasverteilkammern (3, 3‘) einspeisbar sind, wobei einige der Gasein- outlet openings (36') in a cover surface (1') of the body (1) and these G aseintrittsöffnungen (36’) zugeordnete Gasaustrittsöffnungen (15’) in ei- ner base area (1'') of the body (1) and / or some of the gas inlet openings (37a, 37b) are arranged in the wall (35) of the body (1). 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 9. Beobachtungsrohr nach Anspruch 8, dadurch gekennzeichnet, dass in der Gas outlet openings (15', 56a, 56b) arranged in the lower cross-sectional area (12) of the observation tube (1) are arranged radially offset from the gas inlet openings (36', 37a, 37b) assigned to them.

10. Beobachtungsrohr nach Anspruch 8 oder 9, dadurch gekennzeichnet, dasssome gas inlet openings (36', 37a) are located in the same radial plane as the gas outlet openings (15', 56a) assigned to them and some gas inlet openings (37b) are arranged in different radial planes than the gas outlet openings (56b) assigned to them.

11. Beobachtungsrohr nach einem der Ansprüche 7 bis 10, dadurch gekenn- characterized in that some of the gas connecting lines (7a, 7b, 7'a) opening into the lower cross-sectional area (12) of the observation tube (1) are bent in sections.

12. Beobachtungsrohr nach einem der vorhergehenden Ansprüche, gekenn- characterized by one or more pipe sections, wherein at least two pipe sections are separated by an annular collar (16) extending in the circumferential direction and defining the position of the observation tube (1) within the gas inlet element (2).

13. Beobachtungsrohr nach einem der vorhergehenden Ansprüche, dadurch characterized in that the body (1) of the observation tube is manufactured by a 3D printing process or spark erosion.

14. Beobachtungsrohr nach einem der Ansprüche 7 bis 13, dadurch gekenn-characterized in that the body (1) is formed by axially spaced annular plates (41, 41', 41'') surrounding the observation channel (8), 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 wherein some gas connecting lines (7a, 7b, 7'a) are guided outside the observation channel (8) through the ring plates (41, 41', 41'') and open into the lower cross-sectional area (12) of the observation tube (1).

15. Beobachtungsrohr nach Anspruch 14, dadurch gekennzeichnet, dass die Ring plates (41, 41', 41'') have the same diameter among themselves or that the diameters of the ring plates (41, 41', 41'') increase gradually starting from the gas outlet plate (5).

16. Gaseinlassorgan (2) eines CVD-Reaktors mit in mehreren Etagen überei-chambers (3, 3') arranged one above the other, at least one of which is a gas distribution chamber (3, 3'), wherein the chambers (3, 3') are separated from one another by boundary walls (4, 4') and from a process chamber (6) by a gas outlet plate (5), wherein a plurality of gas connecting lines (7, 7', 7a, 7b, 7'a) opening into gas outlet openings (15, 15', 56, 56a, 56b) are arranged between the at least one gas distribution chamber (3, 3') and the gas outlet plate (5), into which gas connection lines process gases from the gas distribution chambers (3, 3') can be fed through gas inlet openings (36, 36', 37, 37a, 37b), wherein in at least some of the boundary walls (4, 4') and in the gas outlet plate (5) an observation r ohr (1) steckt, das einen sich entlang einer Achse von einem oberen Endehas an observation channel (8) extending to a lower end, through which an optical path (P) crossing the gas inlet element (2) can pass, wherein the observation channel (8) has a lower opening surface (9) and an upper opening surface (10), wherein the upper opening surface (9) lies in an upper cross-sectional surface (11) of the observation tube (1), wherein the lower opening surface (9) lies in a projection surface (13) of the upper cross-sectional surface (11) lying in the gas outlet plate (5), characterized in that in a radial 31226N1PCT drg / drag January 16, 2025 Ai 2023-15 at least some of the gas connecting lines (7a, 7b, 7'a) open into the process chamber (6) through the lower cross-sectional area (12) of the observation tube (1) which is delimited inwards by an edge (48) of the lower opening area (9) and radially outwards by an edge (49) of the projection area (13).

17. Gaseinlassorgan nach Anspruch 16, dadurch gekennzeichnet, dass dieGas connection lines (7a, 7b, 7'a) are designed as pipes arranged at least in sections outside the body (1).

18. Gaseinlassorgan nach einem der Ansprüche 16 oder 17, dadurch gekenn- characterized in that axially offset gas inlet openings en (36, 36’, 37, 37a, 37b) mit verschiedenen der Gasverteilkammern (3, 3’) are connected.

19. CVD-Reaktor mit einem Gaseinlassorgan (2) gemäß einem der Ansprü- che 16 bis 18 und einem gasdichten Gehäuse (23), einem in dem Ge- häuse (23) in einer Prozesskammer (6) angeordneten Suszeptor (22) zur Holding substrates (21), a heating device (20) controlled by a control device for tempering the substrates (21) held by the susceptor (22).

20. Beobachtungsrohr, Gaseinlassorgan oder CVD-Reaktor, gekennzeichnet by one or more of the characterizing features of one of the preceding claims. 31226N1PCT drg / drag January 16, 2025 Ai 2023-15

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