Reaction chamber and epitaxial reactor with coating system - Patents.com

Abstract

The reaction chamber (100) is disposed within its cavity (101) and comprises a coating system (90) comprising at least one lower coating element (120) mounted on a lower wall of the cavity and an upper coating element (130) mounted on the lower coating element (120), the lower coating element (120) and the upper coating element (130) defining an insulating interior space for accommodating at least one substrate and creating four walls surrounding this interior space and spaced apart from the cavity walls, the walls of the chamber (100) typically being made from quartz and the coating system (90) typically being made from quartz.

Description

[Technical field]

[0001] The present invention relates to a reaction chamber for epitaxial reactors and to an associated reactor having a "covering system". The (non-contact) "covering system" of the chamber walls is inside the cavity of the reaction chamber and serves to define an insulated space. [Background technology]

[0002] The Applicant is the owner of an international patent application published under number WO2010119430 relating to a reaction chamber for an epitaxial reactor with a coating system. The reaction chamber comprises a box-shaped cavity bounded by four walls in which a reaction and deposition process of semiconductor material takes place on a substrate, the substrate being placed on a rotating susceptor disk. The reaction chamber comprises a coating system disposed within the cavity and defining an inner space within the cavity and an outer space within the cavity. The coating system consists of three elements, namely a first vertically opposed wall and an upper and a second vertically opposed wall, which form an inverted "U" shaped slab resting on the lower wall of the reaction chamber.

[0003] The term "facing wall" in this patent application means a wall that is located at a certain distance from the reference wall and is not in contact with it, between which there is an empty, hollow cavity - reactors are generally made in such a way that there is a gas in the cavity, in particular a process gas or an inert gas, depending on the location and embodiment, in the cavity during the reaction and deposition processes.

[0004] The solution according to WO2010119430, to which reference is made in its entirety, is a simple and effective solution, but it forms an internal "partial covering" of the reaction chamber, since no lower opposing wall is provided. Summary of the Invention [Problem to be solved by the invention]

[0005] A general object of the present invention is to improve upon the prior art.

[0006] In particular, the objectives of improving the "chemical" insulation of the inner space, and / or the "thermal" insulation of the inner space, and / or (in the sense of reducing) fouling on the inner surface of the reaction chamber walls, and / or the possibility of local temperature control in the lower region of the reaction chamber were identified.

[0007] It should be noted that this interior space of the reaction chamber cavity contains the susceptor disk and is adapted to also contain the substrate upon which epitaxial deposition of semiconductor material occurs during the epitaxial growth process.

[0008] As is known, there is a concern for high thickness uniformity and high quality of the semiconductor material layer deposited on the substrate. [Means for solving the problem]

[0009] This general object as well as at least these objects are achieved by what is set out in the appended claims, which form an integral part of this specification.

[0010] The present invention will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 shows a first schematic and simplified (not to scale) cross-sectional view (in the longitudinal direction) of a first embodiment of a reaction chamber according to the invention, the view being subdivided into three views, where view A shows only the chamber, view B shows only the components of the coating system and view C shows the chamber in which the coating system is housed. [Diagram 2] FIG. 2 shows a second schematic and simplified cross-section (not to scale) of the embodiment of FIG. [Diagram 3]FIG. 3 shows a first schematic and simplified horizontal cross-section (not to scale) in a first elevation of the embodiment of FIG. [Figure 4] FIG. 4 shows a second schematic and simplified horizontal cross-section (not to scale) in a second elevation of the embodiment of FIG. [Diagram 5] FIG. 5 shows a third schematic and simplified horizontal cross-section (not to scale) in a third elevation of the embodiment of FIG. [Figure 6] FIG. 6 shows a fourth schematic and simplified horizontal cross-section (not to scale) of the embodiment of FIG. [Figure 7] FIG. 7 shows a fifth schematic and simplified horizontal cross-section (not to scale) of the embodiment of FIG. 1 at a fifth height. [Figure 8] FIG. 8 shows a sixth schematic and simplified horizontal cross-section (not to scale) of the embodiment of FIG. [Figure 9] FIG. 9 shows an exploded perspective view of a second embodiment of a reaction chamber according to the invention (slightly different from the first embodiment). [Figure 10] FIG. 10 shows a schematic partial cross-sectional side view of the embodiment of FIG. 9 combined with a tank. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] As will be readily appreciated, there are various ways of actually implementing the present invention, and the present invention is defined in its principal advantageous aspects in the appended claims, and is not limited by the following detailed description, nor by the accompanying drawings, which refer to two slightly different embodiments.

[0013] It is expressly stated that the technical features described below with respect to certain embodiments are strictly linked and therefore should not be regarded as mutually combined.

[0014] 1 to 8, a reaction chamber 100 for an epitaxial reactor according to the present invention comprises a chamber 80 and a coating system 90 combined with each other, for example as shown in Fig. 1C, where Fig. 1A shows only the chamber 80 and Fig. 1B shows only the coating system 90. The chamber 80 is provided with a box-shaped cavity 101.

[0015] The dimensions of the views of Figures 3 to 8 will be clarified later.

[0016] The cavity 101 is surrounded by at least four walls of the chamber 80, namely the bottom wall 105, the first side wall 106 (left side), the top wall 107 and the second side wall 108 (right side), which according to this embodiment has neither a front nor a rear face, since the reaction gases enter the exhaust gas outlet at the front and leave at the rear. These are in particular essentially four flat slabs, for example made of transparent quartz, joined to each other at their longitudinal edges, although the structure of the chamber may be more complex, as will be seen below, for example with flanges at the front and / or at the rear and / or with stiffening ribs and / or small outer bulkheads.

[0017] In the cavity 101, reaction and deposition processes of the semiconductor material on the substrate take place, more precisely, as will be made clear below, according to the invention, such processes take place only in the "inner space" of the cavity.

[0018] The reaction chamber 100 comprises a "covering system" 90 disposed entirely within the cavity 101, the "covering system" being not in contact with the chamber walls (except for a few small and low lower support elements) but serving to define an "interior space".

[0019] The coating system 90 comprises at least a lower covering element 120 mounted directly or indirectly on the lower wall 105 of the cavity 101; an upper covering element 130 placed directly or indirectly on the lower covering element 120; has.

[0020] The lower covering element 120 and the upper covering element 130 define an “inner space” 102 contained within the cavity 101 and an “outer space” 103 contained within the cavity 101 , and form at least four walls 127 , 136 , 137 , 138 that surround the inner space 102 .

[0021] These four walls 127, 136, 137, 138 of the internal space 102 are spaced apart from the corresponding four walls 105, 106, 107, 108 of the cavity 101 by free spaces in which, depending on the location and the embodiment, a gas may be present, in particular a process gas or an inert gas, and therefore they may be considered as facing walls, the considerations regarding the front and rear made above for the cavity walls also apply to the walls of the internal space. In addition to the free spaces, there may be possible supporting elements of the covering system (see for example elements 112 and 122 in FIG. 1 ) that contribute to achieving the distance.

[0022] The interior space 102 is adapted to accommodate at least one or more substrates undergoing deposition of semiconductor material, the substrates being in particular mounted (directly or indirectly) on a susceptor 150 on a susceptor disk 152 (see, e.g., FIG. 2 ), typically adapted such that the susceptor remains within the reaction chamber at all times, i.e., both during the reaction and deposition processes as well as before and after such processes.

[0023] The coating system according to the invention may be configured to accommodate at least a disk of a substrate support susceptor. Such a disk is made of graphite and is adapted to be heated by induction. In the figures a disk heating system is not shown, which advantageously consists of at least one flat inductor placed close to the disk outside the chamber (for example under the lower wall), see FIG. 10, for example the inductor may be in a cavity 301 suitably electrically insulated from the water. Advantageously the heating system of the reaction chamber according to the invention is of the induction type, although the use of lamps (for example above the upper wall) is not excluded.

[0024] The interior space 102 is isolated from the exterior space 103 by the constant and uniform contact between the elements 120 and 130 .

[0025] From the set of Figures 1C and 2, it can be seen that the upper surface of the susceptor disk 152 is aligned with the upper surface of the wall 127 created by the element 120, and in particular, these surfaces are also aligned with the upper surface of any substrate W supported by the susceptor disk 152 within a particular recess.

[0026] Advantageously, the cavity walls are entirely made of quartz, and the covering system entirely made of quartz, which may be of different types depending on the location. The walls of the cavity and the covering system therefore do not actively contribute to the heating of the cavity, in particular its "inner space" and the substrate, in other words the reaction chamber according to the invention is not of the hot-wall type. In the case of the illustrated embodiments (in particular the embodiment of Figures 2 to 10), the only element which actively contributes to the heating of the cavity, in particular its "inner space" and the substrate, is the susceptor, in particular its rotating disk.

[0027] Typically and preferably, the covering system 90 further comprises a base covering element 110 which is placed directly on the lower wall 105 of the cavity 101 and serves as a further (indirect) closing element of the interior space 102, in which case the lower covering element 120 is placed directly or indirectly on the base covering element 110.

[0028] Covering element 130 may be outlined as an inverted "U" shaped slab (see, e.g., FIG. 1B). Covering element 120 may be outlined as an inverted "U" shaped slab (see, e.g., FIG. 1B). Covering element 110 may be outlined as a flat slab (see, e.g., FIG. 1B), except for the "feet" described below.

[0029] Typically and preferably, the base covering element 110 rests directly on the lower wall 105 of the cavity 101 only via the support elements 112. Although eight support elements, known as "feet", are shown in Fig. 8 by way of example, four for the first part and four for the second part, their number may be different, i.e. less, for example ranging from a minimum of 3 to a maximum of 30. The support elements are typically small, for example each measuring 3 mm 2 ~300mm 2 The support elements may typically be low, for example between 0.5mm and 5.0mm in height.

[0030] The base covering element 110 is essentially in the form of a flat rectangular slab 117 .

[0031] The base covering element 110 is made of clear quartz.

[0032] The base covering element 110 consists of two parts (substantially equal to each other) mechanically coupled to each other, in particular a first of the two parts being located upstream and a second of the two parts being located downstream with respect to the flow direction of the reaction gases. This can be seen in particular in FIG. 9.

[0033] The base covering element 110 has a (small) central hole 114 adapted to the passage of the rotating shaft 154 of the substrate support susceptor 150, the diameter of the hole and the diameter of the shaft being slightly different (e.g. 2-20 mm). In particular, the two parts of the slab each define half of the hole by their mechanically bonded edges.

[0034] The upper covering element 130 is in the form of a flat rectangular slab 137, preferably having two shoulders 132 on two opposite longitudinal edges of the flat slab. The element 130 can be said to be in the form of an inverted "U" shaped slab. The two shoulders 132 form the two side walls 136 and 138 of the interior space 102, and the slab 137 forms the top wall of the interior space 102.

[0035] The upper cladding element 130 is made of clear quartz.

[0036] The upper covering element 130 is made of a single piece.

[0037] The lower covering element 120 is preferably in the form of a rectangular flat slab 127 having shoulders, e.g. longitudinal shoulders 122 and / or transverse shoulders 123, corresponding to at least some edges of the flat slab, in particular shoulders 122 on two opposite longitudinal edges of the flat slab (see e.g. Figs. 1B and 1C). The element 120 can also be said to have the shape of an inverted "U" shaped slab. The slab 127 forms the lower wall of the interior space 102.

[0038] The underside cover element 120 is made from opaque quartz.

[0039] The lower covering element 120 consists of two parts (substantially equal to each other) mechanically coupled to each other, in particular a first of the two parts being located upstream and a second of the two parts being located downstream with respect to the flow direction of the reaction gases, as can be seen in particular in FIG.

[0040] As shown in FIG. 1C, shoulder 132 of element 130 rests directly on shoulder 122 of element 120, particularly on the outer region, and slab 127 rests on the inner region of shoulder 122.

[0041] The lower covering element 120, in particular the flat slab 127, has a (large) central hole 124 adapted to receive the disk 152 of the substrate supporting susceptor 150, the diameter of the hole and the diameter of the disk differing slightly (for example 2-20 mm), the associated gap being traversed by a small flow of reactant gas leaving the space 102 and entering the space between the wall 127 and the wall 117. This can be seen in particular in figures 4 and 5.

[0042] The bottom covering element 120 has a width that is slightly larger than the diameter of the central hole 124 (eg, 2-20 mm).

[0043] The lower covering element 120 has longitudinal shoulders 122 at two opposing longitudinal edges of the flat slab and / or a lateral shoulder 123 at a central hole 124 (see, for example, Figures 6 and 7). Note that since shoulder 123 is not joined (spaced) to shoulder 122, there is no dead space for gas circulation, which facilitates the manufacture of element 120, and in particular the welding of its components.

[0044] The lower wall 105 of the chamber 80 has a (small) hole 109 adapted to let the rotating shaft 154 of the substrate support susceptor 150 pass through, the hole diameter and the shaft diameter varying slightly (eg 2-20 mm).

[0045] For example, it is advantageous to inject a gas flow of hydrogen from the rotating shaft 154 of the susceptor 150 into the reaction chamber to place the area of ​​the holes 109 and 114 under a slight overpressure to prevent reaction gas from escaping from the cavity 101, in particular from the spaces 102 and 103, as well as from the space between the walls 127 and 117.

[0046] 5, 6 and 7, it can be seen that according to this embodiment, the shoulders 122 of the elements 120 are slightly thinner in their intermediate regions, especially in the cross section passing through the center of the hole 124. In this example, the point of maximum thinning is where the upstream and downstream sections meet. The difference in the cross section of the shoulders 122 can also be seen by comparing Figures 1C and 2.

[0047] From this view of the first embodiment it is clear that the space 102 is very well insulated, except for a small (eg 2-20 mm) gap between the shaft 154 and the periphery of the hole 114 in the wall 117 .

[0048] According to a first embodiment, the elements of the reaction chamber may have the following dimensions, for illustrative and non-limiting purposes: Length of elements 106 and 108 in FIG. 1A (i.e., height of chamber 80): 75 mm; Length of elements 105 and 107 in FIG. 1A (i.e., width of chamber 80): 800 mm; Thickness of elements 105-108 in FIG. 1A: 8 mm; Length of element 132 in FIG. 1B: 50 mm; Length of element 137 in FIG. 1B: 780 mm; Thickness of elements 132 and 137 in FIG. 1B: 3 mm; Length of element 122 in FIG. 1B: 20 ​​mm; Length of element 127 in FIG. 1B: 780 mm; Thickness of element 122 in FIG. 1B: 40 mm; Thickness of element 127 in FIG. 1B: 3 mm; Length of element 117 in FIG. 1B: 780 mm; Thickness of element 117 in FIG. 1B: 3 mm; Length of elements 106 and 108 in FIG. 4 (i.e., length of chamber 80): 1100 mm; Diameter of element 152: 720mm, Hole diameter 124:740mm.

[0049] With reference to Figures 3-8, it should be noted that the first height (i.e., the height in Figure 3) corresponds to a plane slightly higher than the top surface of wall 137, the second height (i.e., the height in Figure 4) corresponds to an intermediate plane between wall 137 and wall 127, the third height (i.e., the height in Figure 5) corresponds to a plane passing through wall 127, the fourth height (i.e., the height in Figure 6) corresponds to a plane slightly lower than the bottom surface of wall 127, the fifth height (i.e., the height in Figure 7) corresponds to a plane slightly higher than the top surface of wall 117, and the sixth height (i.e., the height in Figure 8) corresponds to a plane passing through wall 117. It should be noted that in these figures, cross-sectional hatching has been omitted for visual clarity.

[0050] 9 and 10 show a second embodiment 200 of a reaction chamber according to the present invention.

[0051] This second embodiment differs from the first embodiment only in the chamber; in fact, chamber 280 differs somewhat from chamber 80.

[0052] Chamber 280 includes a box-shaped element 281 made of quartz that corresponds exactly to the quartz of chamber 80 .

[0053] The box-shaped element 281 comprises a cavity, also box-shaped, in which a coating system is housed, which may be identical (or similar) to the system 90 of the first embodiment, and in FIG. 9 the components 110, 120 and 130 of the coating system are indicated by the same reference numbers as the components of the system 90.

[0054] The chamber 280 has two flanges 282 and 283 at the longitudinal ends of the element 281. The two flanges each have openings for the reactant gases to enter the chamber cavity and the exhaust gases to exit the chamber cavity.

[0055] In this second embodiment, the elements of the covering system extend at least partially into the flange openings, but do not protrude beyond these openings.

[0056] The chamber 280 has two partitions 286 and 287 on its upper outer surface, the function of which will be described below, which extend transversely to the longitudinal direction of the chamber 280 and are curved in shape, which substantially reflects the shape of a susceptor disk within the interior space defined by the coating system.

[0057] The chamber 280 has a transparent window (eg, 10-20 mm wide) in its upper wall adapted to measure the temperature of the susceptor or substrate.

[0058] In FIG. 10, the chamber 280 is shown in relation to a tank 300 with a cavity 301 adapted to be filled with water (preferably demineralized) during operation of a reactor or equivalent liquid.

[0059] The chamber 280 is mounted to the tank 300 such that the inner surface of the chamber faces the cavity 301 of the tank 300 , and in particular, the flanges 282 and 283 are on the outside of the tank 300 and substantially adjacent to the vertical walls of the tank 300 .

[0060] As shown diagrammatically in Figure 10, in use the water level in cavity 301 is such that it just touches the underside of chamber 280 and cools it by a small amount, e.g., 1-10 mm. Typically such water is circulated and cooled.

[0061] At the underside of the chamber 280, cooling is obtained partly by a gas flow (typically an air flow) and partly by a liquid flow (typically a flow of preferably demineralized water).

[0062] Liquid flow occurs between the two partitions 286 and 287 and eventually reaches a cavity 301 of the tank 300 that cascades downward from the edge of the top wall of the chamber 280, as shown diagrammatically by the arrows in Figure 10. Gas flow occurs elsewhere.

[0063] Although not shown in FIG. 10, an inductor (suitably electrically insulated) is arranged within the cavity 301 to heat at least one susceptor disk arranged within the interior space defined by the coating system by electromagnetic induction; see, for example, patent document WO2018083582.

[0064] From the above, it can be seen that the reaction chamber according to the invention is particularly applicable to epitaxial reactors for growing silicon on silicon substrates.

[0065] One or more technical features of the present invention can be advantageously combined with one or more technical features of earlier inventions of the same Applicant, such as those described and shown in International Patent Applications WO2016001863, WO2017137872, WO2017163168, WO2018065852 and WO2018083582, which are incorporated herein by reference.

[0066] According to a further aspect, the invention relates precisely to the inner coating elements of the reaction chamber, i.e. the components that make up the coating system, for example with reference to the coating system 90 shown in Fig. 1, the coating elements being designated 110, 120, 130. Advantageously, each of these elements may be entirely made of quartz. Advantageously, each of these elements may have its own configuration (with three different configurations and three different sizes in Fig. 1) that is particularly adapted to form the coating system when these components are assembled and mated.

Claims

1. A reaction chamber (100) for an epitaxial reactor, the chamber (100) comprising a cavity (101) in which a reaction and deposition process of a semiconductor material on a substrate occurs, and comprising a coating system (90) disposed within the cavity (101), the cavity (101) being surrounded by four walls (105, 106, 107, 108), the coating system (90) comprising a lower coating element (120) resting on the lower wall (105) of the cavity (101), and an upper coating element (130) resting on the lower coating element (120), the lower coating element (120) and the upper coating element (130) defining an internal space (102) included in the cavity (101) and an external space (103) included in the cavity (101), and forming four walls (127, 136, 137, 138) surrounding the internal space (102), the walls (127, 136, 137, 138) of the internal space (102) being spaced from the walls (105, 106, 107, 108) of the cavity (101) by an empty space, the internal space (102) being adapted to accommodate at least one substrate for receiving deposition of a semiconductor material, the internal space (102) being isolated from the external space (103), reaction chamber (100).

2. the walls (105, 106, 107, 108) of the chamber (100) being entirely made of quartz, and the coating system (90) being entirely made of quartz, reaction chamber (100) according to claim 1.

3. the coating system (90) being configured to accommodate at least one rotating disk (152) of a substrate support susceptor (150), the disk (152) being made of graphite and adapted to be heated by induction, reaction chamber (100) according to claim 2.

4. the reaction chamber (100) according to claim 1, wherein the coating system (90) further comprises a base coating element (110) directly placed on the lower wall (105) of the cavity (101), and the lower coating element (120) is placed on the base coating element (110).

5. the reaction chamber (100) according to claim 4, wherein the base coating element (110) is directly placed on the lower wall (105) of the cavity (101) only by feet (112).

6. The reaction chamber (100) according to claim 4, wherein the base covering element (110) is in the form of a flat rectangular slab (117).

7. The reaction chamber (100) according to claim 4, wherein the base covering element (110) is made of transparent quartz.

8. The base covering element (110) consists of two parts that are mechanically coupled to each other, a first one of the two parts is located upstream, and a second one of the two parts is located downstream with respect to the reaction gas flow direction. The reaction chamber (100) according to claim 4.

9. The reaction chamber (100) according to claim 4, wherein the base covering element (110) has a central hole (114) adapted to the passage of the rotating shaft (154) of the substrate support susceptor (150). The reaction chamber (100) according to claim 4.

10. The reaction chamber (100) according to claim 1, wherein the upper covering element (130) is in the form of a flat rectangular slab having two shoulders (132) at two opposite edges of the flat slab. The reaction chamber (100) according to claim 1.

11. The reaction chamber (100) according to claim 10, wherein the upper covering element (130) is made of transparent quartz.

12. The reaction chamber (100) according to claim 10, wherein the upper covering element (130) consists of a single part.

13. The reaction chamber (100) according to claim 1, wherein the lower covering element (120) is in the form of a flat rectangular slab having shoulders (122, 123) corresponding to at least some edges of the flat slab. The reaction chamber (100) according to claim 1.

14. The reaction chamber (100) according to claim 13, wherein the lower covering element (120) is made of opaque quartz.

15. The lower covering element (120) consists of two parts that are mechanically coupled to each other, a first one of the two parts is located upstream, and a second one of the two parts is located downstream considering the flow direction of the reaction gas. The reaction chamber (100) according to claim 13.

16. The reaction chamber (100) according to claim 13, wherein the lower covering element (120) has a central hole (124) configured to receive the disk (152) of the substrate support susceptor (150).

17. The reaction chamber (100) according to claim 15, wherein the lower covering element (120) has at least one of shoulders (122) at two opposite edges of the flat slab or a shoulder (123) at the central hole (124). The reaction chamber (100) according to claim 15.

18. An inner coating element (110, 120, 130) for a reaction chamber of an epitaxial reactor, the inner coating element (110, 120, 130) being configured to be a component of the coating system (90) of the reaction chamber according to any one of claims 1 to 17.

19. The inner coating element (110, 120, 130) according to claim 18, which is entirely made of quartz.

20. An epitaxial reactor comprising at least one reaction chamber according to any one of claims 1 to 17.

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