Observation tube with curved gas connection lines placed inside

Abstract

The present invention relates to an observation tube (1) for a gas inlet assembly (2) adjacent to a process chamber (6) of a CVD reactor through a gas outlet plate (5), comprising a main body (1), wherein the main body (1) is designed to be hermetically fitted within boundary walls (4, 4') that vertically delineate at least one gas distribution chamber (3, 3') and bores (47, 47', 47'') of the gas outlet plate (5) arranged vertically above each other when installed in the gas inlet assembly (2), and comprises an observation channel (8) extending along an axis from the top end to the bottom end, through which an optical path (P) can pass, and wherein the gas distribution chambers (3, 3') are fluidly connected to gas connection lines (7, 7', 7a, 7'a, 7b, 7c) that open to the process chamber (6), and the gas connection lines (7a, 7b, 7c, At least some of the 7'a) paths are established along the observation channel (8) and separated from the observation channel (8) through the main body (1), at least in sections.

Description

Technology Field

[0001] The present invention relates to an observation tube for a gas inlet assembly of a CVD reactor, wherein the gas inlet assembly comprises chambers arranged in a plurality of upper and lower sections relative to each other, at least one of the chambers is a gas distribution chamber, the chambers are separated from each other by boundary walls and separated from the process chamber by a gas outlet plate, and a plurality of gas connection lines opening into gas outlet openings are arranged between at least one gas distribution chamber and the gas outlet plate, and process gases from the gas distribution chambers can be supplied to the gas connection lines through the gas inlet openings, and the observation tube is inserted into at least some of the boundary walls and the gas outlet plate, and the observation tube has an observation channel extending along an axis from the top to the bottom, and an optical path can pass through the observation channel across the gas inlet assembly, and the observation channel has a lower opening surface and an upper opening surface, the upper opening surface is located in the upper cross-sectional plane of the observation channel, and the lower cross-sectional plane is located in the projection plane of the upper cross-sectional plane located on the gas outlet plate.

[0002] The present invention also relates to a gas inlet assembly comprising such an observation tube.

[0003] The present invention also relates to a CVD reactor comprising a gas inlet assembly having such an observation tube. Background Technology

[0004] DE 10 2020 112 569 A1 discloses an identical device having a gas inlet assembly for supplying process gases to a process chamber of a CVD reactor. The gas inlet assembly comprises a plurality of gas distribution chambers arranged vertically above and below each other between a cover plate and a gas outlet plate, each gas distribution chamber being connected to gas connection lines opening to the gas outlet plate. The gas outlet openings are uniformly distributed across the front surface of the gas outlet plate facing the process chamber. Additionally, an observation tube is provided that can be inserted into the gas inlet assembly. The observation tube is inserted into an insertion opening arranged in the cover plate and extends to the gas outlet plate. An insertion tube functioning as an observation channel may be inserted into the observation tube, for example, an optical path of a pyrometer extends through the insertion tube. Additionally, the observation channel is used to supply process gases to the process chamber. Process gases are supplied laterally to the observation channel through a flow channel open to the gas distribution chamber and flow out from the observation channel into the process chamber through an opening opening to the gas outlet plate. The observation channel has sections with different diameters, and the uppermost opening cross-section is larger than the lowermost opening cross-section located at the gas outlet plate. The channel opening into the process chamber is located within the projected area of ​​the upper cross-sectional area of ​​the observation tube. This regular distribution of gas outlet openings is interrupted in the frontal area located within the projected area of ​​the upper cross-sectional area of ​​the observation tube. This results in non-uniformity in the supply of process gases.

[0005] The present invention is based on the task of improving the gas inlet assembly of a CVD reactor in a manner advantageous for use.

[0006] The above problem is solved by the invention described in the claims. The dependent claims not only represent advantageous improvements to the independent claims but are also independent solutions to the above problem.

[0007] First, an observation tube is provided for installation in a gas inlet assembly of a CVD reactor comprising a plurality of gas distribution chambers arranged vertically above and below each other between a cover plate and a gas outlet plate. The observation tube extends through these gas distribution chambers to a process chamber located below the gas distribution chambers. An observation channel extends through the observation tube along an axis perpendicular to the gas outlet plate, and an optical path traversing the gas inlet assembly can pass through the observation channel. A plurality of gas connection lines opening into the process chamber may be arranged between the gas distribution chambers and the gas outlet plate. Some of these gas connection lines may be routed through the observation tube outside the observation channel. Process gases from the gas distribution chambers can be separated from each other via the gas connection lines and supplied to the process chamber.

[0008] In a first embodiment, the observation tube may be an integral cylindrical body having a wall (35) through which gas connection lines pass. The observation tube may have an upper cross-sectional area and a lower cross-sectional area. The upper cross-sectional area may be larger than the lower cross-sectional area. An observation channel extending along an axis perpendicular to the gas outlet plate may be arranged within the observation tube. The observation channel may be a bore within the observation tube. However, the observation channel may be, for example, a tubular body inserted into the observation tube. The observation channel may have a plurality of channel sections having different diameters. Preferably, the upper channel section may have an opening area larger than the opening area of ​​the lower channel section. This reduction in diameter may be achieved, for example, by a stepped and / or bent tube section. The upper opening area of ​​the observation channel may be located within the upper cross-sectional area of ​​the observation tube. The lower opening area may be located within the projection plane of the upper cross-sectional area located at the gas outlet plate of the gas inlet assembly. The projection plane may be a plane located in the plane of the gas outlet plate onto which the upper cross-sectional area of ​​the observation tube is mathematically projected. The projection plane may be a plane corresponding to the upper cross-sectional area offset along the axis of the observation channel. The projection plane may correspond to the upper cross-sectional area. The lower cross-sectional area of ​​the observation tube is bounded radially inward by the edge of the lower opening area of ​​the observation channel and bounded radially outward by the edge of the projection plane. Gas connection lines passing through the wall of the observation tube may open into this lower cross-sectional area of ​​the observation channel. Gas connection lines may open into the gas outlet plate itself and / or into outlet extensions arranged on the front of the gas outlet plate facing the process chamber. The outlet extensions may be, for example, cylindrical bodies. However, the outlet extensions may take other shapes. The lower opening of the observation channel may open into the outlet extensions.

[0009] Gas connection lines extend between the gas inlet opening and the gas outlet opening, respectively. The gas outlet openings can be located at the intersections of imaginary grid lines that are regularly distributed across the entire front surface of the gas outlet plate. This regular arrangement pattern extends to the lower cross-sectional area of ​​the observation tube. In this way, the regular distribution of gas outlet openings on the front surface of the gas outlet plate is not interrupted in the region of the lower cross-sectional area.

[0010] In one embodiment, gas outlet openings arranged in outlet extensions may be located at the intersections of imaginary grid lines extending at a 60° angle relative to each other. In this case, three outlet extensions may be located at the vertices of an equilateral triangle, and at the center of the equilateral triangle is one of the gas outlet openings arranged in the gas outlet plate itself. Within the lower cross-sectional area of ​​the observation tube, outlet extensions may be arranged, for example, at the vertices of a regular hexagon. An opening of the observation channel may be located at the center of the circumscribed circle of this hexagon. An opening of the observation channel may be located within the outlet extensions. Gas outlet openings opening into the gas outlet plate itself may be arranged at the vertices of two regular hexagons. The first hexagon may have a smaller circumscribed circle, and the second hexagon may have a larger circumscribed circle than the circumscribed circle of the hexagon having the vertices where the outlet extensions are located. These gas outlet openings may therefore have different radial distances. The arrangement pattern of the gas outlet openings can extend across the entire surface of the gas outlet plate. In particular, the gas outlet openings can be regularly arranged across the entire front surface of the gas outlet plate.

[0011] Some of the gas inlet openings assigned to the gas outlet openings of the gas outlet plate may be arranged on the upper surface of the cylindrical body of the observation tube. In particular, the gas inlet openings arranged on the upper surface may be assigned to the gas outlet openings arranged on the outlet extensions. The gas inlet openings may be arranged regularly around the upper opening of the observation channel. For example, the gas inlet openings may be arranged on radial planes that extend at a fixed angle relative to each other, e.g., 60°. This arrangement may correspond, for example, to the arrangement of the outlet extensions in the lower cross-sectional area of ​​the observation tube. Thus, the gas inlet openings may be arranged on the vertices of a regular hexagon, and the circumscribed circle of the regular hexagon is larger than the circumscribed circle of the hexagon where the gas outlet openings arranged on the outlet extensions assigned to the gas inlet openings are located. The gas inlet openings and the gas outlet openings may therefore be arranged radially offset relative to each other.

[0012] Additionally, gas inlet openings may also be arranged on the outer surface of the cylindrical observation tube. For example, the gas inlet openings may be transverse holes arranged on the wall of the tube body. The gas inlet openings may be arranged at regular intervals along the circumferential direction of the observation tube on the outer surface. Each gas inlet opening may have the same radial distance from the axis of the observation channel. Gas outlet openings may be arranged at the same height on the outer surface or axially offset from each other. The gas inlet openings arranged on the outer surface may be assigned to the gas outlet openings arranged within the lower cross-sectional area of ​​the observation tube on the gas outlet plate itself. For example, some of the gas inlet openings arranged on the outer surface may be assigned to the gas outlet openings arranged at the vertices of the first hexagon on the gas outlet plate itself. Others of the gas inlet openings may be assigned to the gas outlet openings arranged on the second hexagon on the gas outlet plate. For example, the gas inlet openings may be arranged in circumferential pairs on the outer surface. A pair of gas inlet openings may be arranged in different radial planes, and the gas outlet openings assigned to each may be arranged in the same radial plane. However, the gas outlet openings may also be located in radial planes different from the radial planes of the corresponding gas inlet openings.

[0013] Due to different radial distances between the gas inlet openings and the gas outlet openings assigned to each of them, the gas connection lines may be bent section by section. In particular, the gas connection lines may extend obliquely or in a non-linear path with respect to the axis of the observation channel in sections of the observation channel where the inner or outer diameter of the observation channel varies.

[0014] Since the cross-sectional area of ​​the upper channel section may be larger than that of the lower channel section, the wall thickness of the wall of the observation tube in the upper tube section of the cylindrical body of the observation tube where the upper channel section is located may be smaller than the wall thickness in the lower tube section where the lower channel section is located. Consequently, within each radial plane of the observation tube outside the observation channel, fewer gas connection lines can be routed through the upper tube section than can be routed through the lower tube section.

[0015] The observation tube can be inserted into the gas inlet assembly in such a manner that it forms a continuous connection between vertically stacked gas distribution chambers and a process chamber adjacent to the gas outlet plate. The gas distribution chambers may be separated from one another by boundary walls having aligned insertion openings into which the observation tube can be inserted. The upper surface of the observation tube may be coplanar with one of the boundary walls. In one embodiment, the tube body may comprise at least two tube sections separated from one another by a ring collar. The ring collar may protrude circumferentially from the wall of the tube body. The edge of the insertion opening of one of the boundary walls may form a step into which the ring collar is seated. The ring collar may also be seated in a pocket formed by the boundary wall. In this way, axial displacement of the observation tube within the gas inlet assembly can be prevented.

[0016] Additionally, the annular collar may have a recess that functions, for example, as a positioning aid. A protrusion arranged on the broad side of the boundary wall or a protrusion formed in a pocket of the boundary wall may engage with the recess. In this engaged position, the rotational position of the observation tube within the insertion opening may be fixed. This ensures that when the observation tube is seated in the insertion opening, the arrangement pattern of gas outlet openings within the lower cross-sectional area of ​​the observation tube is aligned without misalignment with the arrangement pattern of gas outlet openings arranged in the gas outlet plate surrounding the insertion opening.

[0017] The observation tube can be fixed to the insertion opening. For example, the observation tube can be welded to the boundary walls. However, the observation tube may also be detachably connected to the boundary plates. Sealing elements can be used, for example, to seal the gas distribution chambers against each other in the area of ​​the insertion openings.

[0018] The gas inlet openings of the observation tube may be connected to different gas distribution chambers in an axially offset manner. When the observation tube is inserted into the gas inlet assembly, the gas inlet openings arranged on the outer surface may be connected to a first gas distribution chamber located above the process chamber. The gas outlet openings arranged on the upper surface of the observation tube may be connected to a second gas distribution chamber arranged above the first gas distribution chamber. A process gas different from that supplied through the second gas distribution chamber may be supplied through the gas connection lines via the first gas distribution chamber. For example, a process gas containing Group V elements may preferably be supplied to the process chamber through the first gas distribution chamber. A process gas containing Group III elements may be supplied through the second gas distribution chamber. There may be only one gas distribution chamber, or there may be more than two gas distribution chambers, each containing different or the same process gases. In addition to gases containing Group III and Group V elements, other gases, such as cleaning gases, may also be supplied to the process chamber.

[0019] Among a plurality of gas distribution chambers arranged vertically above and below each other, the uppermost gas distribution chamber may be closed at the rear by a cover plate of the gas inlet assembly. The cover plate may have an insertion opening aligned with the upper opening of the observation tube. An insertion tube may be inserted into the observation tube through this insertion opening. The upper section of the insertion tube may extend outside the gas inlet assembly. The insertion tube may extend straight into the observation tube. The insertion tube has a cavity that extends the observation channel extending through the observation tube upon insertion. The cavity may have an inner diameter that remains constant over the entire length of the insertion tube.

[0020] The upper opening of the insertion tube may correspond to the upper opening of the observation channel. A sensor, particularly an optical sensor in the form of a pyrometer, may be positioned at or above the upper opening, and the optical path of said sensor extends through the observation channel. The upper opening may be substantially larger than the lower opening of the observation channel. A large upper opening allows for a large optical sensor area, which enables high measurement accuracy even at low process temperatures. On the other hand, the area of ​​the lower opening of the observation channel is selected to represent the smallest possible incident area for the optical path guided through the observation channel.

[0021] The outer diameter of the insertion tube may be larger than the inner diameter of the intermediate channel section of the observation channel extending through the observation tube. The intermediate channel section may have a larger inner diameter than the lower channel section adjacent to the intermediate channel section. The end face of the wall surrounding the lower opening of the insertion tube may be seated on a stepped or angled channel section arranged between the channel sections.

[0022] The insertion tube can be hermetically secured to the gas inlet assembly by a fastening element. The fastening element may be a flange secured by a gasket to a wide side surface facing outward of the cover plate of the gas inlet assembly.

[0023] Bores, particularly transverse bores, may be arranged in the tube section of the insertion tube to form a flow channel. Process gas may be supplied to an observation channel through the flow channel. The bores preferably connect the observation channel to a process chamber that is closed by a cover plate. However, the observation channel may also be fluidly connected to another gas distribution chamber. The process gas supplied to the observation channel may be, for example, a purge gas used to purge the observation channel. The process gas flows into the process chamber through the observation channel.

[0024] In an additional embodiment, the observation tube may include a plurality of axially spaced annular plates surrounding a sheath tube in which the observation channel is arranged. The space between the axially spaced annular plates is formed as an annular groove. The annular plates may be arranged and sealed within the bores of the boundary walls. The annular plates may be connected and sealed to the rims (edges) of the bores. The sheath tube may have an opening formed by an upper end and an opening formed by a lower end. The upper opening may open to a gas distribution chamber closed by a cover plate. The lower opening may open to a process chamber. The sheath tube may have sections having different outer and inner diameters. A plurality of gas connection lines may be routed outside the sheath tube by penetrating the annular plates axially, at a certain distance from the outer wall of the sheath tube and / or parallel to each section. The gas connection lines may be formed section by section as tubes extending obliquely or non-linearly with respect to the axis of the observation channel. In particular, in the transition regions between sections of the outer tube having different outer diameters, the gas connection lines can be bent section by section. The gas connection lines can be formed into individual gas pipes.

[0025] Annular plates may be arranged within the openings of boundary plates that separate the gas distribution chambers from one another. The diameters of the openings correspond approximately to the diameters of the annular plates. The cross-sectional areas of all annular plates may be the same or different. The cross-sectional area of ​​the upper annular plate may be larger than that of the lower annular plate located coplanar with the gas outlet plate. Gas connection lines passing through the annular plates open into an outlet area located coplanar with the lowest annular plate, which is located at the opening of the gas outlet plate. The outlet surface is located within the projected plane of the uppermost annular plate. The thickness of the annular plates may be slightly greater than that of the boundary plates. The annular plates may hermetically seal the openings. For example, sealing elements may be provided to prevent uncontrolled gas flow between the gas distribution chambers through the openings.

[0026] Gas connection lines can be routed through vertical bores arranged in annular plates. Here, too, any gaps between the inner walls of the bores and the outer walls of the gas pipes—for example, gaps caused by tolerances—are hermetically sealed, for example, by sealing elements. The sealing elements may be, for example, sealing washers or sealing rings. The annular plates themselves may also be designed as sealing elements.

[0027] As in the first embodiment, an insertion tube may be inserted into an observation tube. The insertion tube may have sections having different outer and inner diameters. The insertion tube may have an upper section having a larger outer diameter than the lower section adjacent to the upper section. The lower section may extend into the sheath tube. The lower section may be adjacent to the upper section while forming a step. The step may be seated on the end face edge of the observation tube or on the uppermost annular plate, with a sealing element—such as a sealing ring—interposed between them. The step may press the sealing element against the opening edge of the sheath tube to prevent gas from penetrating from a gas distribution chamber located above the sheath tube to a gas distribution chamber located below it. Gas flow through the gap resulting from the tolerance between the outer wall of the lower section of the insertion tube and the inner wall of the upper section of the sheath tube may also be sealed by this sealing element.

[0028] In a further embodiment of the present invention, the body of the observation tube may form an annular groove extending in a circumferential direction. The annular groove may be formed by the wall of the body. The annular groove may preferably extend continuously in a circumferential direction across the wall of the body. The annular groove provides access to gas inlet openings arranged within the annular groove. The gas outlet openings may be fluidly connected to gas connection lines extending through the wall of the body of the observation tube. Each gas connection line may extend parallel to the longitudinal axis of the observation tube. However, the gas connection lines may be bent at least in sections. The groove may also extend only in sections in a circumferential direction, in which case recesses are provided only within the area of ​​the gas inlet openings to allow gas flow from the gas distribution chamber to the gas supply lines extending through the wall of the observation tube.

[0029] As in the previously described embodiments, an insertion tube may be inserted into the observation tube. Upon insertion, the insertion tube may extend the observation channel formed by the observation tube by an additional section. The inner diameter of the observation channel extending through the observation tube and the insertion tube may vary section by section or continuously over the entire length of the observation tube and the insertion tube. For example, the inner diameter may increase from the observation channel of the observation tube to the observation channel section of the insertion tube. The inner diameter may also increase continuously from top to bottom over the entire length of the observation channel extending through the observation tube and the insertion 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 insertion tube may have a sealing ring that is seated in a circumferential groove in the end section inserted into the observation tube. The sealing ring prevents uncontrolled gas flow from one of the gas distribution chambers into the observation channel through a gap located between the outer wall of the end section of the insertion tube and the inner wall of the insertion opening of the insertion tube.

[0031] Gas outlet openings are arranged at equal circumferential intervals around the observation channel, and the gas outlet openings are located on the upper end face of the collar defining the lower boundary of the annular groove.

[0032] The annular groove may preferably be located at the height of one of the gas distribution chambers, particularly, for example, a first gas distribution chamber supplying hydrides. Gases supplied to the gas distribution chamber may flow through gas inlet openings arranged in the annular groove into gas lines extending through the walls of the observation tube and into the process chamber of the CVD reactor.

[0033] The CVD reactor according to the present invention may include a housing that is hermetically sealed to the outside. A susceptor for receiving substrates may be located within the housing below a gas inlet assembly into which an observation tube according to the present invention is inserted. The susceptor may be heated to a process temperature by a heating device arranged below the susceptor. A process chamber may be located between the gas inlet assembly and the susceptor according to the present invention. A gas outlet member may extend annularly around the susceptor. The housing may include a housing cover forming a cover plate of the gas inlet assembly, so that the gas inlet assembly becomes part of the housing cover. A cooling chamber may be arranged below the gas distribution chambers. The cooling chamber may be directly adjacent to the gas outlet plate. Gas connection lines and an observation tube may preferably extend across the cooling chamber. A plurality of gas connection lines, which are routed outside the observation tube through boundary walls and a gas outlet plate, may be formed into small tubes.

[0034] The body of the observation tube may be composed of multiple parts or be a single part. Observation channels and gas connection lines may be formed into bores within the body. The observation tube may be manufactured using a 3D printing process or electrical discharge machining. Brief explanation of the drawing

[0035] Examples of the present invention are described below with reference to the accompanying drawings. The drawings represent the following: FIG. 1 is a cross-sectional view of a CVD reactor according to the present invention having a gas inlet assembly (2) of a first embodiment, FIG. 2 is an enlarged view of the lower surface of the gas outlet plate (5) in direction II of FIG. 1. FIG. 3 is an enlarged view of the gas inlet assembly (2) in Section III of FIG. 1, showing an observation tube (1) inserted into boundary walls (4, 4') and a gas outlet plate (5), and an insertion tube (29) inserted into the observation tube (1). FIG. 4 is an observation tube (1) according to the embodiment shown in FIG. 1, FIG. 2 and FIG. 3, FIG. 5 is a cross-sectional view along line VV of FIG. 4, showing gas connection lines (7a, 7b) connecting the gas distribution chamber (3) to the process chamber (6). FIG. 6 is a top view of the end face of the observation tube (1) in direction VI of FIG. 5, in which gas inlet openings (36') connected to gas connection lines (7'a) are arranged around the upper opening (45) of the observation tube (1). FIG. 7 is a cross-sectional view along line VII-VII of FIG. 4, wherein gas inlet openings (37a, 37b) connected to the first gas distribution chamber (3) are arranged on the wall (35) of the observation tube (1), and gas connection lines (7a, 7b) are connected to the gas inlet openings (37a, 37b). FIG. 8 is a cross-sectional view along line VIII-VIII of FIG. 6, showing gas connection lines (7'a) that open into outlet extensions (14) starting from the top surface (1') and protruding from the observation tube (1) toward the process chamber (6). FIG. 9 is a top view of the lower surface of an observation tube (1) facing the process chamber (6) in direction IX of FIG. 4. FIG. 10 is a cross-sectional view along line XX of FIG. 9; FIG. 11 is a perspective view of a section of FIG. 10 showing outlet extensions (14) protruding from the base surface (1'') of the observation tube (1). FIG. 12 is a perspective view of a second embodiment of an observation tube (1), wherein gas inlet openings (36') and sealed boreholes (38) connected to gas connection lines (7b) are arranged on the upper surface (1') of the observation tube (1) around the upper opening (45). FIG. 13 is a top view of the end face of the observation tube (1) in direction XIII of FIG. 12, FIG. 14 is a cross-sectional view along line XIV-XIV of FIG. 13, FIG. 15 is a cross-sectional view along line XV-XV of FIG. 13, FIG. 16 is a cross-sectional view along line XVI-XVI of FIG. 13, FIG. 17 is a cross-sectional view along line XVII-XVII of FIG. 13, FIG. 18 is a cross-sectional view of a CVD reactor according to the present invention having a gas inlet assembly (2) of a second embodiment, FIG. 19 is a drawing of the gas outlet plate (5) of the gas inlet assembly (2) in the direction XIX of FIG. 18, FIG. 20 is a cross-sectional view along line XX-XX of FIG. 19, FIG. 21 is a cross-sectional view of a CVD reactor according to the present invention, showing a third embodiment of an observation tube (1) inserted into a gas inlet assembly (2). FIG. 22 is a cross-sectional view through the main body (1) of the observation tube of the third embodiment, FIG. 23 is an observation tube (1) according to the third embodiment shown in FIG. 21 and FIG. 22, FIG. 24 is a cross-sectional view along line XXIV-XXIV of FIG. 22. Specific details for implementing the invention

[0036] FIG. 1 illustrates a CVD reactor having a hermetic housing (23) for depositing III-V layers on substrates (21), for example. A process chamber (6) is located within the housing (23). The process chamber (6) is bounded by a cover plate (24) at the top and by a susceptor (22) at the bottom. The susceptor (22) may be made of graphite or a similar material. The susceptor (22) and the process chamber (6) located thereon may be heated by a heating device (20) arranged below the susceptor (22). This may be achieved by thermal conduction, thermal radiation, or induction. The heating device (20) may be, for example, an RF coil or a resistance coil. The substrates (21) to be heat-treated in the process chamber (6) are arranged on the surface of the susceptor (22) facing the cover plate (24), and in particular, III-V layers are deposited on the surface of the substrates.

[0037] A gas inlet assembly (2) is arranged above a process chamber (6). The gas inlet assembly (2) includes a plurality of gas distribution chambers (3, 3') arranged vertically above and below each other, separated by boundary walls (4, 4'). At least one gas supply line (25, 26) is opened to each gas distribution chamber (3, 3') to supply process gases to the gas distribution chambers (3, 3'). The gas inlet assembly (2) has a gas outlet plate (5) facing the process chamber (6). A plurality of gas connection lines (7, 7', 7a, 7b, 7'a) are opened to the gas outlet plate (5) facing the front portion (46) of the gas outlet plate (5) to connect the gas distribution chambers (3, 3') to the process chamber (6).

[0038] First gas connection lines (7, 7a, 7b) connected to the first gas distribution chamber (3) are opened into the gas outlet plate (5) itself. For example, a first process gas containing hydrides of Group V elements is preferably supplied to the first gas distribution chamber (3) through a gas supply line (25). A second gas distribution chamber (3') is positioned above the first gas distribution chamber (3) and is bounded upward by a cover plate (24). A second process gas may be supplied to the second gas distribution chamber (3') through a gas supply line (26). Second gas connection lines (7', 7'a) are connected to the second gas distribution chamber (3') and are opened into outlet extensions (14) protruding from the front portion (46) of the gas outlet plate (5). The second process gas preferably contains organometallic compounds of Group III elements. The first and second process gases are supplied to the process chamber (6) together with a carrier gas such as hydrogen or nitrogen.

[0039] A cooling chamber (17) extends behind the gas outlet plate (5), and a coolant can be supplied to the cooling chamber (17) through the coolant inlet (18). The coolant can exit the cooling chamber (17) through the coolant outlet (19). The cooling chamber (17) is separated from the gas distribution chamber (3) by a boundary wall (4'). Gas connection lines (7, 7a, 7b, 7', 7'a) extend across the cooling chamber (17).

[0040] FIG. 2 shows details of the front portion (46) of the gas outlet plate (5). Gas outlet openings (15, 15', 56, 56a, 56b) connected to gas connection lines (7, 7a, 7b, 7', 7'a) are regularly arranged across 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 the first gas outlet openings (56, 56a, 56b) arranged directly on the gas outlet plate (5). The second gas connection lines (7', 7'a) connected to the second gas distribution chamber (3') open into the gas outlet openings (15, 15') arranged on the end face of the outlet extensions (14), respectively.

[0041] Gas outlet openings (15, 15') are located at the intersections of imaginary grid lines extending 60° apart across the front portion (46). Gas outlet openings (15, 15') are each located at the vertices of an equilateral triangle. Gas outlet openings (56a, 56b) are arranged at each intersection of the perpendicular bisectors of the equilateral triangle—which are also angle bisectors. However, gas outlet openings (15, 15', 56, 56a, 56b) may be arranged according to a different arrangement pattern. In the arrangement pattern shown in FIG. 2, an observation channel (8) extending through the observation tube (1) according to the present invention is opened where the gas outlet opening (15, 15') is to be located along one of the grid lines connecting the gas outlet openings (15, 15'). Multiple gas outlet openings (15') are regularly arranged just around the edge (48) that defines the lower opening (28) of the observation channel (8).

[0042] As illustrated in FIG. 3, the observation tube (1) extends parallel to the gas connection lines (7, 7a, 7b, 7', 7'a), respectively, through the bores (47, 47', 47'') of the boundary walls (4, 4') and the gas outlet plate (5). In the embodiment illustrated in FIG. 1 through 17, the observation tube (1) is a single cylindrical body. The upper surface (1') extends coplanarly with the broad side surface of the boundary wall (4) toward the cover plate (24). The lower surface (1'') ends coplanarly with the gas outlet plate (5).

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

[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 perpendicular to the gas outlet plate (5). The observation channel (8) is opened to an outlet extension (14) and includes a plurality of channel sections (30, 31, 32) having different diameters. The upper channel section (32) has an upper opening area (10) that is larger than the cross-sectional area (9) of the lower channel section (30). The upper opening area (10) of the observation channel (8) is located within the upper cross-sectional area (11) of the observation tube (1). The lower opening area (9) of the observation channel (8) is located within the projected area (13) of the upper cross-sectional area (11) of the observation tube (1) located at the gas outlet plate (5). In the embodiment illustrated in FIG. 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 radially inwardly bounded by the edge (48) of the lower opening surface (9) of the observation channel (8) and radially outwardly bounded by the edge (49) of the projection surface (13) (see FIG. 2). The projection surface is a plane that is congruent with the upper cross-sectional area (11) in the plane of the gas outlet plate.

[0045] According to the present invention, some gas outlet openings (15', 56a, 56b) are located in the lower cross-sectional area (12). Gas connection lines (7a, 7b, 7'a) opening into these gas outlet openings (15', 56a, 56b) are routed through the wall (35) of the observation tube (1). Second gas connection lines (7'a) connected to the second gas distribution chamber (3') start from the upper surface (1') of the observation tube (1). Corresponding second gas inlet openings (36') are arranged on the upper surface (1') around the upper opening (45) of the observation channel (8). The second gas inlet openings (36') are arranged on radial planes that extend at an angle of 60° relative to each other 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') to the process chamber (6) through the second gas connection lines (7'a). The second gas outlet openings (15') assigned to the second gas inlet openings (36') are each arranged in the same radial plane as the corresponding second gas inlet opening (36').

[0046] First gas inlet openings (37a, 37b) connected to first gas connection lines (7a, 7b) are arranged on the side of the wall (45) of the observation tube (1) (see FIG. 4), and through these first gas inlet openings (37a, 37b), the first process gas flows from the first gas distribution chamber (3) to the first gas connection lines (7a, 7b).

[0047] As illustrated in FIG. 4, the first gas inlet openings (37a, 37b) are arranged in pairs on the wall (45) of the observation tube (1) above the annular collar (16). The gas inlet openings (37a, 37b) are located on different radial planes. However, the gas outlet openings (56a, 56b) assigned to the gas inlet openings (37a, 37b) are located on 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 with respect to the gas inlet openings (36', 37a, 37b) assigned to each. To compensate for this radial offset, the gas connection lines (7a, 7b, 7'a) connecting the gas inlet openings (36', 37a, 37b) to the gas outlet openings (15', 56a, 56b) are bent section by section.

[0049] In the embodiment of the observation tube (1) illustrated in FIG. 3, the upper channel section (32) has a larger diameter than the middle channel section (31), and the middle channel section (31) has a larger diameter than the lower channel section (30). The reduction in diameter is achieved in each case by the offset channel sections (53, 53'). Due to the reduction in the diameter of the observation channel (8), the wall thickness of the observation tube (1) in the area of ​​the upper channel section (32) is smaller than in the areas of the middle channel section (31) and the lower channel section (30). Thus, it is possible to establish the path of two first gas connection lines (7a, 7b) in the radial plane through the wall (35) of the observation tube (1) in the area having a thicker wall thickness. However, in the area of ​​the upper channel section (32), only one second gas connection line (7'a) extends through the wall (35) in the radial plane.

[0050] The first gas connection lines (7b) and the second gas connection lines (7'a) extend substantially parallel to the contour of the observation channel (8). At the height of the bent channel sections (35, 35'), these gas connection lines (7b, 7'a) are each bent radially inward or radially outward section by section. On the other hand, the first gas connection lines (7a) extend parallel to the first and second gas connection lines (7, 7') arranged outside the observation tube (1) along their entire length.

[0051] An insertion tube (29) is inserted into the observation tube (1). To this end, the cover plate (24) is provided with an insertion opening (45) aligned with the bores (47, 47', 47''). The lower section of the insertion tube (29) can be inserted through the insertion opening (45). The lower section of the insertion tube (29) extends straight into the upper tube section of the observation tube (1). The upper end of the insertion tube (29) protrudes beyond the cover plate (24) of the gas inlet assembly (2). Due to the straight extension of the insertion tube (29), an optical path can be extended through the insertion tube (29). The upper section forms an upper opening (27), which also functions as an upper opening of the observation channel (8, 8'). Accordingly, the cavity of the insertion tube (29) extends the observation channel (8), which extends through the observation tube (1), beyond the cover plate (24) of the gas inlet assembly (2) by a second section (8'). A thermometer or similar device may be connected to the upper opening (27).

[0052] The upper section of the insertion tube (29) is connected to a flange (34), and using this flange (34), the insertion tube (29) can be secured to the outside of the cover plate (24). This is done by interposing a sealing ring (39). In this way, the insertion opening (45) is sealed so that process gas from the second gas distribution chamber (3') cannot escape from the gas inlet assembly (2) through the insertion opening (45) to the outside through the cover plate (24).

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

[0054] The inner diameter (51) of the insertion tube (29), and thereby 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 insertion tube (29) is aligned with the upper opening (27). In the embodiment illustrated in FIG. 3, the upper opening (27) and the lower opening (44) have the same opening area. The edge (52) of the insertion tube (29) surrounding the lower opening (44) rests on the inclined surface (50) formed by the bent channel section (53). This bent channel section (53) is located at the height of the first gas distribution chamber (3).

[0055] FIG. 4 shows 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.

[0056] As illustrated in FIG. 5, the first gas inlet (37a) is arranged with only a slight radial offset from the assigned gas outlet (56a). Accordingly, the first gas connection line (7a) connecting the first gas inlet (37a) to the first gas outlet (56a) extends substantially parallel to the axis of the observation channel (8). The gas connection line (7a) starts from the gas inlet opening (37a) and bends vertically downward toward the base surface (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 obliquely with respect to the axis of the observation channel (8) section by section, because the first gas outlet opening (56b) is offset radially inward with respect to the first gas inlet opening (37b) assigned to it and is arranged in a different radial plane (see FIG. 7).

[0058] FIG. 6 shows a top view of the upper surface (1') of the observation tube (1). The second gas inlet openings (36') are arranged at equal intervals on the surrounding surface surrounding the upper opening of the observation tube (1). The second gas inlet openings (36') are arranged in radial planes oriented at an angle of 60° relative to each other. This arrangement corresponds to the arrangement of the corresponding gas outlet openings (15') shown in FIG. 2, wherein the second gas outlet openings (15') are moved radially inward relative to the second gas inlet openings (36') within each radial plane.

[0059] As illustrated in FIG. 7, the first gas connection line (7b) starts from the second gas inlet opening (37b) and extends horizontally from the first section parallel to the axis of the observation channel (8). As illustrated in FIG. 5, following this first section, a second section extends parallel to the axis of the observation channel (8). At the height of the approximately bent channel section (53'), a third section extends obliquely with respect to the axis of the observation channel (8) and curves toward the observation channel (8); this third section transitions into a fourth section that extends parallel to the axis of the observation channel (8) and opens into the gas outlet opening (56b).

[0060] FIG. 8 shows second gas connection lines (7'a) extending through the wall (35) of the observation tube (1), which start from second gas inlet openings (36') arranged on the upper surface (1') of the observation tube (1) and open to corresponding gas outlet openings (15') of the outlet extensions (14). The gas outlet openings (15') are offset radially inward relative to the gas inlet openings (36'). This offset is compensated by the radially inwardly bent section of the second gas connection lines (7'a) at the height of the bent section (53) of the observation channel (8).

[0061] FIG. 9 shows the gas outlet surface of the observation tube (1). Gas outlet openings (15', 56a, 56b) extend outward from the lower opening (28) of the observation channel (8) in the lower cross-sectional area (12) of the observation tube (1), spaced apart from each other at equal intervals. The first gas outlet openings (56a), the first gas outlet openings (56b), and the second gas outlet openings (15') are each located at the vertices of an imaginary hexagon around the opening (28). The circumcircle of the hexagon formed by the second gas outlet openings (15') is larger than the circumcircle of the hexagon formed by the first gas outlet openings (56b) and smaller than the circumcircle of the hexagon formed by the first gas outlet openings (56a). The gas outlet openings (15') are each located at the center of the base surfaces of the cylindrical outlet extensions (14). The areas of the gas outlet openings (15', 56a, 56b) are substantially the same. However, the areas of the first gas outlet openings (56a, 56b) and the second gas outlet openings (15') may differ in size. The number of the first gas outlet openings (56a, 56b) within the lower cross-sectional area (12) of the observation tube (1) is twice the number of the second gas outlet openings (15'). Over the entire surface of the gas outlet plate (5), the ratio of the second gas outlet openings (56a, 56b) to the first gas outlet openings (15, 15') is 2:1.

[0062] As illustrated in FIGS. 10 and 11, the first gas outlet openings (56a, 56b) are coplanar with the surface of the gas outlet plate (5). On the other hand, the second gas outlet openings (15') are spaced apart from the gas outlet plate (5) because they are arranged on the end face of the outlet extensions (14). As a result, the process gases are mixed only in the planar region of the gas outlet openings (15') below the gas outlet plate (5).

[0063] The gas connection lines (7a, 7b, 7'a) may be holes extending through the wall (35) of the observation tube (1) or small tubes inserted into the wall (35).

[0064] FIG. 12 illustrates another embodiment of the observation tube (1). For manufacturing reasons, when producing gas connection lines (7b, 7'a) that extend obliquely with respect to the axis of the observation channel (8) section by section, it is necessary to bore the individual line sections separately. Line sections extending parallel to the axis of the observation channel (8) are created by drilling holes in the upper surface (1') of the observation tube (1), and line sections extending obliquely with respect to the axis of the observation channel (8) are created by drilling holes in the wall (35) of the observation tube (1). The bore holes (38) thus created, which do not function as process gas inlets (36', 37a, 37b), are sealed. Two first gas inlet openings (37a, 37b) and the sealed bore (38') are arranged in three groups on the wall (35) of the observation tube (1) at the height of the intermediate channel section (31).

[0065] As can be seen in FIG. 12, the annular collar (16) surrounding the observation tube (1) in the circumferential direction can be opened.

[0066] A second gas inlet opening (36') and a sealed bore hole (38) connected to the first gas connection line (7b) are arranged in pairs on the upper surface (1') of the observation tube (1) (see FIG. 13). As shown in FIG. 13, the inclined sections of the first gas connection line (7b) extend in a plane perpendicular to the upper surface (1'). The inclined section of the second gas connection line (7'a) extends in a plane perpendicular to the upper surface (1') but angularly offset from this plane.

[0067] FIG. 14 illustrates an exemplary cross-section of the first gas connection line (7b) and the second gas connection line (7'a). The section of the second gas connection line (7'a) that extends at an angle with respect to the axis of the observation channel (8) at the height of the intermediate channel section (31) has a bore hole (38') sealed in the wall (35) of the observation tube (1). The seal prevents process gas from flowing from the first gas distribution chamber (3) into the second gas connection line (7'a), thereby preventing premature mixing of process gases within the gas connection lines (see FIG. 16 and FIG. 17).

[0068] The first gas connection lines (7b) that open into the first gas outlet openings (56b) have a bore hole (38) sealed at the end face of the observation tube (1) and a bore hole (38'') sealed at the wall (35) of the observation tube (1) at the height of the lower channel section (30) (see FIG. 14 and FIG. 17). On the one hand, these prevent process gas from the second gas distribution chamber (3') from flowing into the first gas connection lines (7b), and on the other hand, prevent coolant from the coolant chamber (17) from flowing into the first gas connection lines (7b).

[0069] In FIG. 15, gas connection lines (7a) that open to the first gas outlet openings (56a) are connected to the first gas inlet opening (37a) on the outer surface of the observation tube (1), and process gas can flow from the first gas distribution chamber (3) to the process chamber (6) through the first gas inlet opening (37a).

[0070] FIG. 18 shows a gas inlet assembly (2) having a third embodiment of an observation tube (1). Two gas distribution chambers (3, 3') are provided and are fluidly connected to a gas outlet plate (5) through gas connection lines (7, 7a, 7b, 7', 7'a) assigned to each of them. The openings (15, 15', 56a, 56b) of the gas connection lines (7, 7a, 7b, 7', 7'a) at the gas outlet plate (5) are arranged alternately distributed across the cross-sectional area of ​​the gas inlet assembly (2), as shown in FIG. 19. The gas outlet openings (15, 15', 56a, 56b) are each spaced equally apart along imaginary grid lines extending at an angle of 90° relative to each other over the gas outlet surface (54) facing the process chamber (6). According to the present invention, the lower opening (28) of the observation channel (8) extending through the outer tube (40) of the observation tube (1) is opened at the intersection of a virtual grid line extending through the gas outlet openings (15, 15') and a virtual grid line extending through the gas outlet openings (56, 56b). The outer tube (40) extends parallel to and of the same length as the second gas connection lines (7'). The upper opening of the outer tube (40) is opened to the second gas distribution chamber (3').

[0071] As illustrated in FIG. 20, the observation tube (1) comprises a plurality of annular plates (41, 41', 41'') that are axially spaced apart from each other and surround the outer tube (40). Adjacent annular plates (41, 41', 41'') are spaced apart from each other by a gap formed by an annular groove (58). Gas inlet openings (37b) are arranged in the annular groove (58), and these gas inlet openings (37b) are connected to some of the gas connection lines (7b) through which paths are established through the annular plates (41, 41', 41''). The annular plates (41, 41', 41'') are each hermetically fitted into the bores (47, 47', 47'') of the boundary walls (4, 4') or the gas outlet plate (5). In the embodiment illustrated in FIG. 20, the annular plates (41, 41', 41'') have the same cross-sectional area, so that the projected area (13) of the upper cross-sectional area (11) of the observation tube (1) corresponds to the lower cross-sectional area (12) of the observation tube (1). However, the annular plates (41, 41', 41'') may have different cross-sectional areas. For example, the upper annular plate (41) may have a larger cross-sectional area than the lower annular plate (41''). The thickness of the annular plates (41, 41', 41'') may be greater than the thickness of the boundary walls (4, 4') and / or the gas outlet plate (5). According to the present invention, some of the gas connection lines (7b, 7'a) are routed through the annular plates (41, 41', 41'') outside the outer tube (40). The gas connection lines (7b, 7'a) are designed as tubes that are hermetically fitted into the 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 the gas outlet openings (15', 56b') assigned to each. The gas outlet openings (15', 56b) are offset radially inward from the gas inlet openings (36', 37b).As a result, the gas connection lines (7b, 7'a) are bent section by section. In the embodiment illustrated in FIG. 20, the gas connection lines (7b, 7'a) are extended at an angle with respect to the axis of the observation channel (8) at the height of the bent channel section (53'). The gas connection lines (7, 7') that are routed outside the observation tube (1) are extended parallel to the axis of the observation channel (8).

[0072] The cover plate (24) has an insertion opening (45) into which an insertion tube (29) is inserted, and the lower end of the insertion tube (29) is inserted into the outer tube (40). The cavity (8') of the insertion tube (29) forms an extension of the observation channel (8) that extends 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 insertion tube (29) has an upper insertion tube section having an outer diameter and inner diameter (51) larger than the lower insertion tube section. The lower insertion tube section is adjacent to the upper insertion tube section, forming a step (42), and extends straight into the outer tube (40). The lower opening (44) of the insertion tube (29) is located approximately at the height of the first gas distribution chamber (3). The lower insertion tube section may be longer and, for example, may extend along the entire length of the outer tube (40). The outer contour of the insertion tube (29) may be aligned with the inner contour of the outer tube (40).

[0074] The step (42) forms a sealing surface adjacent to the first wide side of the sealing ring (39). The other wide side of the sealing ring (39) is seated over the wide side of the boundary wall (4) facing the cover plate (24), with the sealing ring (39) interposed, just like the upper opening of the observation tube (1). This sealing ring (39) seals the gap (55) extending between the inner wall of the outer tube (40) and the outer wall of the lower insertion tube section.

[0075] As in the embodiment shown in FIG. 3, the insertion tube (29) of FIG. 20 is fixed to the outside of the cover plate (24) by a flange (34) with a sealing ring (33) interposed therein.

[0076] FIGS. 21 through 24 illustrate a third embodiment of the observation tube (1). The body (1) of the observation tube is substantially cylindrical and extends vertically from the upper gas distribution chamber (3') to the gas outlet plate (5) when installed in the gas inlet assembly (2). The body (1) is hermetically fitted into the bores (47, 47', 47'') of the boundary walls that define the gas distribution chambers (3, 3') downwardly and into the gas outlet plate (5). For example, after being inserted into the bores (47, 47', 47''), the body (1) may be welded to the boundary walls (4, 4') or the gas outlet plate.

[0077] The cover plate (24) has an insertion opening (45) into which an insertion tube (29) is inserted, as in the previously described embodiments, and the lower end of the insertion tube (29) is inserted into the body (1) of the observation tube. The lower end section of the insertion tube (29) forms a ring groove into which a sealing ring (59) is seated, and this sealing ring (59) hermetically closes the sealing surface between the outer wall of the lower end section of the insertion tube (29) and the inner wall of the insertion cavity of the observation tube (1). The insertion tube (29) is attached to the cover plate (24), for example, by a flange (34).

[0078] The cavity of the insertion tube (29) extends the observation channel (8) extending through the main body (1) by a second section (8'). The inner diameter of the observation channel (8, 8') increases continuously from the middle channel section (31) of the observation channel (8) to the insertion tube (29), that is, to the upper end of the insertion tube (29). At the upper end section of the middle channel section (31), the inner diameter of the observation channel (8) of the observation tube (1) corresponds to the inner diameter of the observation channel (8') of the insertion tube (29) at the lower end section of the insertion tube (29). The starting point of the continuous increase in the inner diameter of the observation channel (8, 8') extending through the observation tube main body (1) and the insertion tube may be located within the first channel section (30) of the observation tube (1).

[0079] The purge gas can be supplied to the observation channels (8, 8') through a bore (43) that extends horizontally through the wall of the insertion tube (29). A sealing ring (59) seated in an annular groove of the wall of the insertion tube (29) prevents unwanted purge gas flows from entering the second gas distribution chamber (3').

[0080] The inner diameter of the insertion cavity for the insertion tube (29) is formed by the upper channel section (32) of the observation tube (1) and is substantially constant over the entire length of the upper channel section (31) of the main 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) are adjacent to each other, forming a step. The lower end of the insertion tube (29) can be seated on the step.

[0081] The wall (35) of the main body (1) of the observation tube forms an annular groove (58) that extends in a circumferential direction. The annular groove (58) allows gases from the first gas distribution chamber (3) to flow into gas inlet openings (37c) arranged within the wall (35) or the annular groove (58), and these gas inlet openings (37c) are connected to gas connection lines (7c) that extend through the wall (35). The gas connection lines (7c) pass through the wall (35) of the main body (1) and open into gas outlet openings (56c) arranged in the gas outlet plate (5). The gas connection lines (7c) passing through the main body (1) extend in a straight line and parallel to the longitudinal axis of the main body (1). However, the gas connection lines (7c) may be bent in sections as in the previously described embodiments.

[0082] Both the outer wall of the insertion tube (29) and the outer wall of the observation tube (1) have sections having different outer diameters. However, the outer diameter of the insertion tube (29) may be substantially constant over the entire length of the insertion tube (29), as shown in FIG. 3.

[0083] The foregoing descriptions serve to describe the inventions included in the application as a whole, each of which independently advances the prior art through combinations of at least the following features, and two, several, or all of these combinations of features may be combined, namely:

[0084] An observation tube characterized in that at least some of the gas connection lines (7a, 7b, 7c, 7'a) are each routed along the observation channel (8) in at least section by section and separated from the observation channel (8) through the main body (1).

[0085] An observation tube characterized in that the observation tube (1) is an integral body extending along the axis of the observation channel (8) and has a wall (35) on which at least some of the gas connection lines (7a, 7'a, 7b, 7c) are arranged.

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

[0087] An observation tube characterized by gas connection lines (7c) passing through the wall (35) of the main body (1) extending in a straight line and parallel to the longitudinal axis of the main body (1).

[0088] An observation tube characterized in that an insertion tube (29) is inserted into a main body (1), and an observation channel (8) extending through the main body (1) is extended by a second section (8'), and the inner diameter of the observation channel (8, 8') varies continuously at least section by section over the length of the main body (1) and the insertion tube (29).

[0089] An observation tube characterized in that the observation channel (8) and gas connection lines (7a, 7'a, 7b, 7c) are formed by the bores of the main 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 on the upper surface (1') of the main body (1) and the gas outlet openings (15') assigned to the gas inlet openings (36') are arranged on the lower surface (1'') of the main body (1), or some of the gas inlet openings (37a, 37b) are arranged on the wall (35) of the main body (1).

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

[0094] An observation tube characterized in that some of the gas connection lines (7a, 7b, 7'a) that open into the lower cross-sectional area (12) of the observation tube (1) are bent section by section.

[0095] An observation tube characterized by having one or more tube sections, wherein at least two tube sections are separated by an annular collar (16) extending in a circumferential direction that defines the position of the observation tube (1) within a gas inlet assembly (2).

[0096] An observation tube characterized in that the main body (1) of the observation tube is manufactured by a 3D printing process or electrical discharge machining.

[0097] An observation tube characterized in that the main body (1) is formed by annular plates (41, 41', 41'') spaced apart from each other in the axial direction surrounding the observation channel (8), and some of the gas connection lines (7a, 7b, 7'a) are routed through the annular plates (41, 41', 41'') outside the observation channel (8) and open into the lower cross-sectional area (12) of the observation tube (1).

[0098] An observation tube characterized in that the annular plates (41, 41', 41'') have the same diameter as each other, or the diameters of the annular plates (41, 41', 41'') increase in steps starting from the gas outlet plate (5).

[0099] A gas inlet assembly (2) characterized in that at least some of the gas connection lines (7a, 7b, 7'a) are opened into a process chamber (6) within the lower cross-sectional area (12) of the observation tube (1), which is bordered radially inward by the edge (48) of the lower opening surface (9) and radially outward by the edge (49) of the projection surface (13).

[0100] A gas inlet assembly characterized in that gas connection lines (7a, 7b, 7'a) are formed of tubes arranged outside the main body (1) at least in sections.

[0101] A gas inlet assembly characterized by gas inlet openings (36, 36', 37, 37a, 37b) arranged axially offset from one another and connected to different gas distribution chambers (3, 3').

[0102] A CVD reactor comprising a gas inlet assembly (2) and a hermetic housing (23), a susceptor (22) arranged in a process chamber (6) within the housing (23) to accommodate substrates (21), and a heating device (20) controlled by a control device for temperature control of the substrates (21) accommodated by the susceptor (22).

[0103] All disclosed features (individually and in combination with one another) are essential to the present invention. The disclosure of this application fully incorporates the disclosures of the associated / attached priority documents (copies of prior applications), including the inclusion of the features disclosed in those documents in the claims of this application. Dependent claims are intended to characterize an inventive development independent of the prior art by themselves, without the features of the cited claims, and are particularly intended for the purpose of filing divisional applications based on these claims. The invention specified in each claim may further include one or more of the features described in the foregoing description, particularly those indicated by / or indicated by reference numerals or listed in a list of reference numerals. The present invention also relates to embodiments in which some of the features mentioned in the foregoing description are not implemented, particularly where they are recognized as unnecessary in light of their respective intended use or can be replaced by other means having equivalent technical effects. Explanation of the symbols 1 Observation tube, main body 1' Top surface 1'' base 2 gas inlet assembly 3 First gas distribution chamber 3' 2nd gas distribution chamber 4 boundary wall 4' boundary wall 5 Gas outlet plate 6 process chamber 7 gas connection line 7' gas connection line 7a gas connection line 7b gas connection line 7c gas connection line 7'a gas connection line 8 Observation channel 9 Lower opening area 10 Upper opening area 11 upper cross-sectional area 12 lower cross-sectional area 13 Projected area 14 Exit extension 15 gas outlet 15' gas outlet 16 ring collar 17 cooling chamber 18 Coolant inlet 19 Coolant outlet 20 Heating device 21 substrate 22 susceptor 23 Housing 24 Cover plate 25 gas supply line 26 gas supply line 27 upper opening 28 lower opening 29 insertion tube 30 Lower channel section 31 Middle channel section 32 Upper channel section 33 sealing ring 34 flange 35 wall 36 gas inlet opening 36' gas inlet opening 37 gas inlet opening 37a gas inlet opening 37b gas inlet opening 37c gas inlet opening 38 Sealed boreholes 38' Sealed boreholes 38'' Sealed boreholes 39 sealing ring 40 outer tube 41 annular plate 41' annular plate 41'' annular plate 42 Step 43 complement 44 Lower opening of the insertion tube 45 Insertion opening 46 Front 47 Boers 47' Boers 47'' Boers 48 Edge 49 Edge 50 incline 51 Inner diameter of the insertion tube 52 Edge 53 Bent channel section 53' Bent channel section 54 Outer diameter of the insertion tube 55 interval 56 gas outlet opening 56a gas outlet opening 56b gas outlet opening 56c gas outlet opening 57 Recess 58 Ring home P optical path

Claims

Claim 1 An observation tube for a gas inlet assembly (2) adjacent to a process chamber (6) of a CVD reactor through a gas outlet plate (5), comprising a main body (1), wherein the main body (1) is designed to be hermetically fitted within boundary walls (4, 4') that vertically delineate at least one gas distribution chamber (3, 3') and bores (47, 47', 47'') of the gas outlet plate (5) arranged vertically above each other when installed in the gas inlet assembly (2), and comprising an observation channel (8) extending along an axis from the top to the bottom, through which an optical path (P) can pass, and wherein the gas distribution chambers (3, 3') are fluidly connected to gas connection lines (7, 7', 7a, 7'a, 7b, 7c) that open to the process chamber (6), and at least of the gas connection lines (7a, 7b, 7c, 7'a) An observation tube characterized in that a portion of each section follows the observation channel (8) and is separated from the observation channel (8) and has a path established through the main body (1). Claim 2 An observation tube according to claim 1, characterized in that the observation tube (1) is an integral body extending along the axis of the observation channel (8) and has a wall (35) on which at least some of the gas connection lines (7a, 7'a, 7b, 7c) are arranged. Claim 3 An observation tube according to claim 2, characterized in that the wall (35) of the main body (1) forms a circumferential annular groove (58), and gas inlet openings (37b, 37c) connected to gas connection lines (7b, 7c) passing through the wall (35) are arranged within the annular groove (58). Claim 4 An observation tube according to claim 3, characterized in that gas connection lines (7c) passing through the wall (35) of the main body (1) extend in a straight line and parallel to the longitudinal axis of the main body (1). Claim 5 An observation tube according to any one of claims 1 to 4, wherein an insertion tube (29) is inserted into the main body (1), and the cavity of the insertion tube (29) extends through the main body (1) to an observation channel (8) by a second section (8'), and the inner diameter of the observation channel (8, 8') varies continuously for at least a section over the length of the main body (1) and the insertion tube (29). Claim 6 An observation tube according to any one of claims 1 to 5, characterized in that the observation channel (8) and the gas connection lines (7a, 7'a, 7b, 7c) are formed by bores of the main body (1) of the observation tube. Claim 7 An observation tube characterized in that, in any one of claims 1 to 6, the upper opening area (10) of the observation channel (8) is larger than the lower opening area (9). Claim 8 An observation tube according to any one of claims 1 to 7, wherein process gases from a gas distribution chamber (3, 3') can be supplied to gas connection lines (7a, 7'a, 7b, 7c) through gas inlet openings (36, 36', 37, 37a, 37b, 37c), and some of the gas inlet openings (36') are arranged on the upper surface (1') of the main body (1) and gas outlet openings (15') assigned to the gas inlet openings (36') are arranged on the lower surface (1'') of the main body (1), or some of the gas inlet openings (37a, 37b) are arranged on the wall (35) of the main body (1). Claim 9 An observation tube according to claim 8, characterized in that gas outlet openings (15', 56a, 56b) arranged in the lower cross-sectional area (12) of the observation tube (1) are arranged radially offset from gas inlet openings (36', 37a, 37b) assigned to them. Claim 10 An observation tube according to claim 8 or 9, characterized in that some gas inlet openings (36', 37a) are located in the same radial plane as the corresponding gas outlet openings (15', 56a), and some gas inlet openings (37b) are arranged in different radial planes as the corresponding gas outlet openings (56b). Claim 11 An observation tube according to any one of claims 7 to 10, characterized in that some of the gas connection lines (7a, 7b, 7'a) that open into the lower cross-sectional area (12) of the observation tube (1) are bent section by section. Claim 12 An observation tube according to any one of claims 1 to 11, characterized by having one or more tube sections, wherein at least two tube sections are separated by an annular collar (16) extending in a circumferential direction that can define the position of the observation tube (1) within the gas inlet assembly (2). Claim 13 An observation tube according to any one of claims 1 to 12, characterized in that the main body (1) of the observation tube is manufactured by a 3D printing process or electrical discharge machining. Claim 14 An observation tube according to any one of claims 7 to 13, wherein the main body (1) is formed by annular plates (41, 41', 41'') spaced apart from each other in the axial direction surrounding the observation channel (8), and some of the gas connection lines (7a, 7b, 7'a) are routed through the annular plates (41, 41', 41'') outside the observation channel (8) and open into the lower cross-sectional area (12) of the observation tube (1). Claim 15 An observation tube according to claim 14, characterized in that the annular plates (41, 41', 41'') have the same diameter as each other, or the diameters of the annular plates (41, 41', 41'') increase in steps starting from the gas outlet plate (5). Claim 16 A gas inlet assembly (2) of a CVD reactor comprising chambers (3, 3') arranged in multiple stages vertically relative to each other, wherein at least one of the chambers (3, 3') is a gas distribution chamber (3, 3'), the chambers (3, 3') are separated from each other by boundary walls (4, 4') and separated from a process chamber (6) by a gas outlet plate (5), and a plurality of gas connection lines (7, 7', 7a, 7b, 7'a) opening into gas outlet openings (15, 15', 56, 56a, 56b) are arranged between at least one of the gas distribution chambers (3, 3') and the gas outlet plate (5), and process gases from the gas distribution chambers (3, 3') can be supplied to the gas connection lines through gas inlet openings (36, 36', 37, 37a, 37b), and observation A tube (1) is inserted into at least some of the boundary walls (4, 4') and the gas outlet plate (5), and the observation tube (1) has an observation channel (8) extending along the axis from the top to the bottom, and an optical path (P) across the gas inlet assembly (2) can pass through the observation channel (8), and the observation channel (8) has a lower opening surface (9) and an upper opening surface (10), the upper opening surface (10) is located in the upper cross-sectional area (11) of the observation tube (1), and the lower opening surface (9) is located in the projected area (13) of the upper cross-sectional area (11) located in the gas outlet plate (5), and the lower cross-sectional area (12) of the observation tube (1) — the lower cross-sectional area (12) is bounded radially inward by the edge (48) of the lower opening surface (9) and the edge (49) of the projected surface (13) A gas inlet assembly (2), characterized in that at least some of the gas connection lines (7a, 7b, 7'a) are opened into the process chamber (6), where the boundary is defined radially outwardly by ―. Claim 17 A gas inlet member according to claim 16, characterized in that the gas connection lines (7a, 7b, 7'a) are formed as tubes arranged outside the main body of the observation tube (1) at least in sections. Claim 18 A gas inlet assembly according to either claim 16 or 17, characterized in that gas inlet openings (36, 36', 37, 37a, 37b) arranged axially offset from one another are connected to different gas distribution chambers (3, 3'). Claim 19 A CVD reactor comprising a gas inlet assembly (2) and a hermetic housing (23) according to any one of claims 16 to 18, a susceptor (22) arranged in a process chamber (6) within the housing (23) to accommodate substrates (21), and a heating device (20) controlled by a control device for temperature control of the substrates (21) accommodated by the susceptor (22). Claim 20 An observation tube, gas inlet assembly, or CVD reactor characterized by one or more of the features of any one of claims 1 to 19.

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