Gas Inlet Components for CVD Reactors

Abstract

The invention relates to an exhaust surface (16) of an inlet element (2) or a shield (14) for an inlet element (2) for a CVD reactor (1), the exhaust surface having a plurality of exhaust openings (7, 17) arranged around a center (10), wherein the center points (8′) of the exhaust openings (7, 17) are located at corner points (8′) of polygonal cells (8) which are designed identically and have a geometric center point (9), wherein the edges (8″) of the cells (8) are defined by intersecting reference lines (13, 13′, 13″), wherein the reference lines (13, 13′, 13″) are each assigned to at least two line groups, and the reference lines of the line groups extend straight and parallel to each other over the entire exhaust surface. According to the invention, the center (10) is spaced from the corner points (8′) by a distance of one third ±10% of the length of the edge.

Description

Technical Field

[0001] The present invention relates to an exhaust surface of an inlet element for a CVD reactor or a shield for an inlet element, wherein the exhaust surface has a plurality of exhaust openings arranged around a center, wherein the midpoints of the exhaust openings are located at the corner points of polygonal units that are identically designed and have geometric midpoints, wherein the edges of the units are defined by intersecting reference lines that are correspondingly assigned to at least two line groups, and the reference lines of the individual line groups extend straight and parallel to each other over the entire exhaust surface.

[0002] The invention further relates to a gas inlet element having such an exhaust surface, a shielding plate fixed to the exhaust surface of the gas inlet element, and a CVD reactor having such a gas inlet element or such a shielding plate. Background Art

[0003] The CVD reactor has a gas inlet element through which process gas can be fed into a heatable treatment chamber. Arranged in the treatment chamber is a substrate which is thermally treated in the CVD reactor, for example, by depositing a layer on the substrate surface.

[0004] Such air inlet elements are described in patent documents DE 10 2011 051 778 A1, EP 1 842 938 A2, DE 10 2009 043 840 A1 and US 2017 / 0167024 A1. Patent document DE'778 describes an air inlet element designed as a shower head. The exhaust opening has a hexagonal arrangement. The midpoint of the exhaust opening is located at the corner point of an equilateral triangle. The edges of the unit formed by the equilateral triangle are respectively formed by reference lines. The reference lines are formed by line groups. Each line group has a plurality of reference lines that are spaced at the same distance and extend parallel to each other. The reference lines of different line groups are inclined 120° relative to each other.

[0005] Patent document US'024 describes a showerhead in which the midpoint of the exhaust opening is located at the intersection of reference lines formed by Fermat spirals.

[0006] Patent document WO 2019 / 199620 A1 describes an air inlet element having a bottom side facing a base body, which bottom side has a plurality of inlet openings and outlet openings regularly distributed on the surface. Summary of the invention

[0007] Such an inlet element is used in a CVD reactor in which a relative rotation occurs between the inlet element or the exhaust surface and the base. The base rotates relative to the fixed inlet element about an axis of rotation. The axis of rotation defines a center. The inlet element can have a circular exhaust surface. Such a circular exhaust surface has a center. A circular exhaust plate forming the exhaust surface has a center. A cylindrical inlet element has an end face forming the exhaust surface, which has a center. The exhaust opening has a defined position relative to such a center.

[0008] During the relative rotation, each exhaust opening sweeps over the annular surface of the base to a certain extent, the midpoint of which is the center, i.e., the axis of rotation. If the center is located at the midpoint of the exhaust opening at the center, an annular surface is left around the circular surface, and no exhaust opening moves above the annular surface during the rotation. A similar situation occurs if the center coincides with the midpoint of the unit, and the corner points of the unit are formed by the midpoints of adjacent exhaust openings. Even in this arrangement, not every arc line arranged around the center extends through at least one exhaust opening. This results in a "gap" in the central area of ​​the exhaust surface, for example a circular one, which may lead to an insufficient supply of process gas to the processing chamber.

[0009] The object of the present invention is to improve the feeding of process gas, in particular in the central region of a treatment chamber, from a process engineering perspective.

[0010] The technical problem is solved by the invention specified in the claims, wherein the dependent claims are not only advantageous developments of the invention claimed in the coordinated claims, but also represent independent solutions.

[0011] According to the invention, the position of at least one central exhaust opening is defined with reference to the center of a rotationally symmetrical body, such as an exhaust surface, an exhaust plate, a shield, an air inlet element, etc. It is firstly proposed that, when the exhaust openings are arranged at the corners of identically designed units, the center, i.e., the center point of the circular exhaust surface or the axis of rotation of the base, is offset relative to the corner point and also relative to the center point of the surface of the unit. In an alternative that can also be implemented in combination with the above-mentioned technical solution, the invention proposes that the preferably identically designed exhaust openings constitute central exhaust openings, wherein the center is arranged in the cross section of the exhaust opening and is arranged in particular offset relative to the center point of the preferably circular exhaust opening. In particular, it can be provided that the center is approximately at the edge of the exhaust opening, so that the central exhaust opening rotates around the center to a certain extent during relative rotation. It can also be provided that the distance between the central exhaust opening and the exhaust opening closest to it is less than twice the diameter of the exhaust opening. Advantageously, the distance between the edges of two adjacent exhaust openings is less than the diameter of the exhaust opening, in particular the diameter of the central exhaust opening. In the arrangement structure of the exhaust opening according to the present invention, the circular "gap" described at the beginning will not be formed. Instead, the exhaust opening is arranged on the exhaust surface so that, especially in the area of ​​the center of the exhaust surface, each arbitrary arc line extending around the center intersects with at least one exhaust opening. The reference line whose intersection defines the position of the midpoint of the exhaust opening of the line group can extend straight and parallel to each other on the entire exhaust surface, thereby forming a plurality of regular polygons. A triangular or quadrangular preferably regularly designed polygon can be formed. In this way, the unit defined by the corner points of the reference line and whose edge is the section of the reference line has a geometric midpoint. The midpoint can be the area centroid of the unit. These units constitute the unit at the center. The center is offset relative to each corner point and relative to the midpoint of the surface. The unit can have edges of the same length. The center can be about 1 / 3 ± 10% of the length of the edge from the corner point. The center can be spaced from the corner point in the direction of the angular bisector of the two lines intersecting at the corner point. It can also be provided that the length of the edge is about 7.07 mm ± 10%. The exhaust opening can have a diameter of 4 mm ± 10%. The center can be spaced at a distance of 2 mm ± 10% from the corner point. The arrangement of the exhaust openings on the exhaust surface according to the invention can be realized on the exhaust plate of the intake element. The exhaust plate defines a volume through which a coolant can flow, through which a coolant can flow and / or into which a process gas can be fed, which process gas can enter the process chamber through the exhaust opening. However, it is also provided that the arrangement of the exhaust openings is realized on a shield plate. Such a shield plate is fixed to the intake element adjacent to the exhaust plate. The exhaust opening of the shield plate is aligned with the exhaust opening of the exhaust plate of the intake element. The exhaust plate can consist of metal, refined steel, aluminum or a similar material.The shielding plate can be made of ceramic material, coated graphite or also of metal. The shielding plate can be made of porous material. The shielding plate can have a rough surface.

[0012] The invention also relates to a CVD reactor having a gas-tight and pressure-resistant housing made of metal. An inlet element is located in the housing, the inlet element having the above-mentioned properties and in particular having the shape of a shower head. The exhaust surface extends in the rotation plane of the rotation axis, through which the base is driven to rotate. The upper side of the base forms the bottom surface of the treatment chamber. The exhaust surface of the inlet element forms the upper side of the treatment chamber. The rotation axis of the base defines the center of the inlet element, which, as described above, is offset both relative to the midpoint of the exhaust opening at the center and relative to the midpoint of the unit at the center of the arrangement structure of the exhaust opening. It can be provided that a shielding plate having the above-mentioned properties is arranged between the exhaust plate of the inlet element and the base. The shielding plate can be in contact with the bottom side of the exhaust plate pointing toward the base. However, the shielding plate can also be spaced from the bottom side of the exhaust plate. A temperature control device can be provided. The base can be temperature-controlled by the temperature control device. The temperature control device can be, for example, a heating device. The air inlet element can also have a temperature control device in order to cool or heat the outlet surface.

[0013] The exhaust plate and / or the shield plate can consist of graphite or graphite coated with SiC or with TaC. However, the surface of the air intake element is preferably a refined steel surface. The wall of the air intake element and the exhaust plate can thus consist of refined steel. The exhaust opening of the shield plate can be aligned with the exhaust opening of the exhaust plate of the air intake element. However, the exhaust opening of the shield plate can also be offset relative to the exhaust opening of the exhaust plate of the air intake element.

[0014] The invention further relates to a method for operating a CVD reactor as described above, in which method the susceptor is driven in rotation about an axis of rotation defining a center which is offset both relative to a corner point of the cell at the center and relative to a midpoint of a surface of the cell at the center. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be described in detail below based on embodiments. In the accompanying drawings:

[0016] Figure 1 A CVD reactor of a first embodiment is shown schematically in cross section,

[0017] Figure 2 The exhaust surface 16 of the air inlet element 2 is shown according to Figure 1 Bottom view of line II-II in the figure,

[0018] Figure 3 The enlarged view shows Figure 2 Part III,

[0019] Figure 4 The enlarged view shows Figure 3 Local IV in

[0020] Figure 5 The second embodiment corresponds to Figure 1 . DETAILED DESCRIPTION

[0021] Figure 1 and Figure 5 The structure of a CVD reactor is schematically shown, which is preferably an MOCVD reactor, in which a coating process is carried out, in which a III-V substrate or IV substrate, such as a silicon substrate or the like, is coated with a III-V layer. The coating can be, for example, a gallium arsenide layer, a gallium phosphide layer or a gallium nitride layer. For this purpose, a process gas, in particular a gas mixture, is fed into a gas distribution volume 6 of a gas inlet element 2 designed as a shower head via a gas feed line 19. The gas inlet element can have a plurality of gas distribution volumes 6, which are separated from each other and each have an exhaust opening 7 assigned thereto. A gas of a process gas, for example a hydride of an element of the V main group or an organometallic compound of an element of the III main group, is fed into each gas distribution volume 6.

[0022] The susceptor 3 is located below the gas inlet element 6 and is composed of a coated graphite plate. An axis of rotation 18 is provided, about which the susceptor can be driven in rotation in a rotation plane. A heating device 4 is located below the susceptor 3 in order to heat the susceptor 3 to the process temperature. The CVD reactor 1 can be evacuated by a pump connected to an exhaust port (not shown).

[0023] The underside of the exhaust plate 15 with the exhaust openings 7, which faces the base 33, forms the exhaust surface 16. Figure 2 The exhaust surface 16 is shown in Figure 3 The enlarged detail in FIG. 1 shows that the exhaust openings 7 each have a circular basic contour. In the embodiment, all exhaust openings 7 have the same circular basic contour and a diameter of about 4 mm. The distance between the edges of the two exhaust openings 7 closest to each other is smaller than the diameter of the exhaust opening 7.

[0024] The exhaust openings 7 are evenly distributed on the exhaust surface 16 in a hexagonal arrangement. In the present disclosure, the arrangement of the exhaust openings 7 is described with the help of reference lines 13, 13', 13". There are three groups of reference lines 13, 13', 13", wherein the reference lines 13, 13', 13" extend parallel to each other and are spaced the same distance apart. The reference lines of different line groups are inclined 120° relative to each other. Exhaust openings 7 are arranged at all intersections of the reference lines 13, 13', 13". The reference lines 13, 13', 13" thus define a plurality of identically designed units 8, each of which has the shape of an equilateral triangle. In an embodiment not shown, two line groups can have reference lines that are offset by 90° relative to each other, so that the unit 8 has a rectangular or square shape.

[0025] In the exemplary embodiment described, the corner points 8' of the cells 8 are spaced apart from one another by a distance a of 7.07 mm. The exhaust opening 7 has a midpoint coinciding with the corner point 8' and a diameter of approximately 4 mm. Figure 4 The center 10 is shown, which can be the geometric center point of the exhaust surface 16, which coincides with the center of the rotation axis 18 in the described use case. According to the invention, the center 10 is neither located at the geometric center point 9 of the unit 8 nor at the corner point 8' of the unit 8. In the described embodiment, the center 10 is offset by about 2 mm relative to the corner point 8'. The center 10 is located at the edge of the exhaust opening 7.1 in the center. The center can be located on the angle bisector 9, that is, on the line extending through the corner point 8' and the center point 9. The center 10 can be located between the center point 9 of the unit 8 and the center point of the exhaust opening 7.1 in the center. The center 10 can also be the geometric center point of the exhaust plate 15 or the center of the end face of the air inlet element 2, but can also be arranged at any other position in the cross section of the exhaust opening 7.1 in the center, but not arranged at the center point of the cross section.

[0026] In this arrangement, the two exhaust openings 7.2 and 7.3 are spaced at the same distance from the central exhaust opening 7.1. The distance b between the two edges of the central exhaust opening 7.1 and the adjacent exhaust openings 7.2 and 7.3 is smaller than the diameter D, so that the surface of the exhaust opening 7 during a relative rotation about the center 10 sweeps over a circular surface that is slightly larger than the annular spacing surface between the center 10 and the edges of the adjacent exhaust openings 7.2, 7.3.

[0027] As a result, no annular surface is formed which is not swept by the at least one exhaust opening 7 during a relative rotation of the carrier 3 relative to the exhaust surface 16 .

[0028] Figure 5 The embodiment shown is Figure 1The main difference of the embodiment shown is that a shielding plate 14 is arranged on the surface of the exhaust plate 15 pointing toward the process chamber, and the exhaust opening 17 of the shielding plate is aligned with the exhaust opening 7. Figure 2 , Figure 3 and Figure 4 The arrangement shown corresponds to .

[0029] The shield 14 is arranged here so that its exhaust opening 17 is aligned with the exhaust opening 7 of the exhaust plate 15. In an embodiment not shown, in which the shield 14 is spaced apart from the exhaust plate 15, the exhaust opening 17 can also be arranged offset relative to the exhaust opening 7. In this case, however, it is provided that the exhaust opening 17 in the center of the shield 14 has the aforementioned position.

[0030] The above embodiments are used to illustrate the invention generally included in the present application, which expands the prior art at least by the following feature combinations, respectively and independently, wherein two, more or all of these feature combinations can also be combined, namely:

[0031] An exhaust surface 16 of a gas inlet element 2 for a CVD reactor 1 or for a shield 14 of a gas inlet element 2, characterized in that the center 10 is spaced from the corner point (8') by a distance of one third ±10% of the length of the edge.

[0032] An exhaust surface 16 is characterized in that the cells 8 have edges 8' of equal length.

[0033] An exhaust air surface 16 is characterized in that the center 10 is located offset relative to the center point 9 in the surface of the cell 8 .

[0034] An exhaust surface 16 is characterized in that the cells 8 are regular polygons and / or triangles or quadrilaterals.

[0035] An exhaust surface, characterized in that the length of the edge 8" is 7.07 mm ± 10%.

[0036] An air inlet element, characterized by an air outlet surface 16 according to any one of claims 1 to 4.

[0037] An air intake element is characterized in that the exhaust surface 16 is formed by a shielding plate 14, which is arranged on an exhaust surface 15 having exhaust openings 7 arranged in the same structure.

[0038] A CVD reactor 1 having a housing, characterized by an exhaust gas surface according to one of the preceding claims.

[0039] A CVD reactor, characterized in that the exhaust surface 16 is formed by a shielding plate 14, which is arranged on an exhaust surface 15 having exhaust openings 7 with the same arrangement structure.

[0040] A gas inlet element 2 with an exhaust surface for a CVD reactor is characterized by a shielding plate 14 arranged on the surface of an exhaust plate 15 facing the process chamber, the exhaust opening 17 of the shielding plate being aligned with the exhaust opening 7 of the gas inlet element 2.

[0041] An exhaust surface of an inlet element 2 for a CVD reactor 1 or a shielding plate 14 for the inlet element 2, characterized in that a first distance corresponds at most to the radius of the exhaust openings 7, 17 and a second distance of the midpoint 8' of the exhaust opening 7, 17 at the center relative to the midpoint 8' of the exhaust opening 7, 17 closest to the exhaust opening 7, 17 at the center is less than the sum of the diameters D of the two exhaust openings 7, 17, and / or the center 10 of the exhaust surface 16 is located in the surface of the unit 8 offset both relative to the corner point 8' and relative to the midpoint 9, and / or the length of the edge 8" is less than twice the diameter of the exhaust openings 7, 17, and / or the exhaust openings 7, 17 have a diameter of 4 mm±10%, and / or the center 10 is located on the edge of the exhaust openings 7, 17, and / or the center 10 is offset by 2 mm±10% relative to the corner point 8'.

[0042] An exhaust surface, characterized in that the center 10 is spaced apart from the corner point 8′ in the direction of the angle bisector 12 of two reference lines 13, 13′, 13″ intersecting at the corner point 8′, and / or the length of the edge 8″ is 7.07 mm±10%, and / or the exhaust openings 7, 17 designed identically to each other have a circular basic contour, and / or the length of the edge 8″ is less than twice the diameter of the exhaust openings 7, 17, and / or the exhaust openings 7, 17 have a diameter of 4 mm±10%, and / or the center 10 is located on the edge of the exhaust openings 7, 17, and / or the center 10 is offset by 2 mm±10% relative to the corner point 8′.

[0043] A method for operating a CVD reactor 1, characterized in that a susceptor 3 is rotated about an axis of rotation 18 relative to an inlet element 2 fixed to a housing, wherein a center 10 of an exhaust surface 16 is located in the axis of rotation 18 and is located in the surface of the unit offset both relative to a corner point 8′ and relative to a center point 9.

[0044] However, the diameter of the exhaust openings 7, 17 can also be less than 2 mm, for example, the diameter can be 1.65 mm. In this case, the distance between two adjacent exhaust openings can be 7.07 mm. The midpoint of the exhaust opening closest to the center of the exhaust surface can be spaced 2.3 mm from the center.

[0045] All disclosed features (as individual features or in combination of features) are essential to the invention. Therefore, the disclosure of the present application also includes the entire disclosure of the relevant / attached priority document (copy of the prior application), for which reason the features of the priority document are also incorporated into the claims of the present application. Dependent claims indicate independent and inventive extensions of the prior art by their features even without the features of the cited claims, and in particular divisional applications can be filed on the basis of these dependent claims. The utility model given in each claim may additionally have one or more features that are particularly provided with figure numerals in the preceding description and / or given in the list of figure numerals. The invention also relates to a variety of design methods, in which certain features mentioned in the above description are not implemented, in particular when they are considered to be insignificant for the corresponding purpose of use or can be replaced by other means with the same technical effect.

[0046] Reference numerals list

[0047] 1 CVD reactor

[0048] 2 Intake components

[0049] 3 Base

[0050] 4 Temperature control device

[0051] 5 Matrix

[0052] 6 Gas distribution volume

[0053] 7 Exhaust opening

[0054] 8 units

[0055] 8′ corner point

[0056] 8" Edge

[0057] 9 Midpoint

[0058] 10 Center

[0059] 11 Polygonal faces

[0060] 12 Angle Bisector

[0061] 13 Straight Line

[0062] 14 Shield

[0063] 15 Exhaust plate

[0064] 16 Exhaust surface

[0065] 17 Exhaust opening

[0066] 18 Rotation axis

[0067] 19 Gas input pipeline

Claims

1. An exhaust surface (16) for a gas inlet element (2) of a CVD reactor (1) or for a shield (14) of a gas inlet element (2), the exhaust surface having a circular basic contour with a center (10) and a plurality of exhaust openings (7, 17) arranged around the center (10), the exhaust openings each having a midpoint, wherein: The midpoint of the exhaust opening (7, 17) is located at a corner point (8') of a polygonal unit (8) which is identically designed and has a geometric midpoint (9), wherein the position and length of an edge (8") of the unit (8) are defined by intersecting reference lines (13, 13', 13"), wherein the reference lines (13, 13', 13") are respectively assigned to at least two line groups, and the reference lines of each line group extend straight and parallel to each other over the entire exhaust surface, characterized in that the center (10) is spaced from the corner point (8') by a distance of one third ±10% of the length of the edge.

2. The exhaust surface (16) according to claim 1, characterized in that The units (8) have edges (8") of equal length.

3. The exhaust surface (16) according to claim 1, It is characterized in that The center (10) is located offset relative to the center point (9) in the surface of the unit (8).

4. The exhaust surface (16) according to claim 1, It is characterized in that The unit (8) is a regular polygon.

5. The exhaust surface (16) according to claim 1, It is characterized in that The length of the edge (8") is 7.07 mm ± 10%.

6. The exhaust surface according to claim 1, characterized in that The center (10) is spaced apart from the corner point (8') along the direction of the angle bisector (12) of two reference lines (13, 13', 13") intersecting at the corner point (8').

7. The exhaust surface according to claim 1, characterized in that The exhaust openings (7, 17) which are designed identically to one another have a circular basic contour.

8. The exhaust surface according to claim 1, characterized in that The length of the edge (8") is less than twice the diameter of the exhaust opening (7, 17).

9. The exhaust surface according to claim 1, characterized in that The exhaust opening (7, 17) has a diameter of 4 mm±10% and the center (10) is located on the edge of the exhaust opening (7, 17).

10. The exhaust surface according to claim 1, characterized in that The center (10) is offset from the corner point (8') by 2 mm ± 10%.

11. The exhaust surface (16) according to claim 4, characterized in that The unit (8) is a triangle or a quadrilateral.

12. An air inlet element having a gas distribution volume (6), an exhaust plate (15), The exhaust plate has exhaust openings (7) which are evenly distributed on the exhaust surface (16), characterized in that: The air inlet element has an outlet surface (16) according to claim 1.

13. The air intake element according to claim 12, characterized in that The exhaust air surface (16) is formed by a shielding plate (14) which is arranged on an exhaust air surface (15) having exhaust air openings (7) arranged in the same structure.

14. A CVD reactor having a housing, the CVD reactor having a gas inlet element (2) arranged in the housing and a susceptor (3) for accommodating a substrate (5) to be treated and spaced apart from an exhaust surface (16) of the gas inlet element (2) and rotatably driven about a rotation axis (18), characterized in that: The exhaust surface is the exhaust surface according to claim 1.

15. The CVD reactor according to claim 14, characterized in that The exhaust air surface (16) is formed by a shielding plate (14) which is arranged on an exhaust air plate (15) having exhaust air openings (7) arranged in the same structure.

16. A method for operating a CVD reactor (1) according to claim 14, characterized in that The base (3) rotates about an axis of rotation (18) relative to an air inlet element (2) fixed to the housing, wherein the center (10) of the air outlet surface (16) is located in the axis of rotation 18 and is located in the surface of the unit offset both relative to the corner point (8') and relative to the center point (9).

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