Reaction chamber for deposition reactor with gap and bottom closure element and reactor - Patents.com

Abstract

The reaction chamber (100) is used in a reactor for depositing a layer of semiconductor material on a substrate, and comprises a tube (110) made of quartz, having a cylindrical shape, and adapted to be positioned in use with its axis (111) vertical, the tube (110 having a cylindrical internal cavity (112) extending along the entire length of the tube (110) and adapted to contain a flowing liquid, the chamber (100) being made of quartz and secured to a first lower end of the tube (110) to close the internal cavity (112) and allow the liquid to flow out from the lower part of the cavity. The chamber (100) further comprises an annular closure element (120) for preventing the liquid from flowing through the void (112), the closure element (120) having an annular recess (122) at its upper portion facing the internal void (112) so that the flowing liquid can reach the recess (122) at the bottom, and the chamber (100) further comprises a set of internal conduits (130) within the internal void (112), the internal conduits (130) extending from a first lower region of the tube (110) to a second upper region of the tube (110) to facilitate circulation of the liquid flowing through the void (112).

Description

[Technical field]

[0001] The present invention relates to a reaction chamber for a deposition reactor having a gap and a bottom closure element, and a reactor using same. [Background technology]

[0002] The reaction chambers of the reactors need to be cooled when the reaction temperatures (their interiors) are high.

[0003] This applies in particular to reactors for depositing a layer of semiconductor material on a substrate, sometimes called a "seed", for example, where the reaction temperature may be, for example, 800-1200°C for epitaxial deposition of silicon, or 1600-3000°C for epitaxial deposition of silicon carbide, and the result of the deposition may be, for example, a (generally thick) layer or an ingot (i.e. a long crystal).

[0004] It is desirable for the walls of the reaction chamber to be cooled efficiently and uniformly.

[0005] Furthermore, it is desirable for the cooling system to operate reliably, i.e., not fail.

[0006] The applicant is focused on reaction chambers comprising a tube made of quartz, having a cylindrical shape and adapted to be positioned with its axis vertical in use, and in particular the applicant is focused on large chambers (e.g. greater than 50 cm in diameter and greater than 100 cm in height).

[0007] These chambers are used in particular in reactors for growing silicon carbide ingots starting from a "seed" at very high temperatures, for example above 2000°C. Summary of the Invention [Problem to be solved by the invention]

[0008] A general object of the present invention is to provide an effective and reliable reaction chamber. [Means for solving the problem]

[0009] This general object is substantially achieved by what is recited in the appended claims, which form an integral part of this specification.

[0010] The subject of the invention is also a reactor using such a reaction chamber.

[0011] The present invention will become more readily apparent from the following detailed description considered in conjunction with the accompanying drawings. [Brief description of the drawings]

[0012] [Figure 1] 1 shows a (highly schematic) longitudinal section of an embodiment of a reaction chamber according to the invention; [Diagram 2] 2 shows a partial longitudinal section of a closure element of the reaction chamber of FIG. 1; [Diagram 3] FIG. 2 shows a first partial longitudinal cross-sectional view (highly schematic) of the tube of the reaction chamber of FIG. 1; [Figure 4] FIG. 2 shows a second partial longitudinal cross-sectional view (highly schematic) of the tube of the reaction chamber of FIG. 1; [Diagram 5] FIG. 2 shows a configuration diagram of a reactor using the reaction chamber of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] As can be readily understood, 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 either the following detailed description or the appended claims.

[0014] 1 to 6 all show the same example of an embodiment of the present invention, with reference number 100 indicating the reaction chamber as a whole and reference number 1000 indicating the reactor as a whole.

[0015] 1 shows a chamber 100 enclosing an internal reaction and deposition region 170 in which at least one substrate (not shown) is placed, typically supported by a support element (not shown), called a "susceptor", especially when the element has the function of not only supporting the substrate but also of heating it. A (generally thick) layer is deposited on the substrate during a so-called "growth" process at high temperature. FIG. 1 does not show any of the components inside the reaction chamber 100, which are not relevant for the purposes of the present invention.

[0016] The chamber 100 comprises a base 150, a cover 160 and a surrounding wall, specifically the surrounding wall consisting of a tube 110 made of quartz, having a cylindrical shape and adapted to be positioned in use with its axis 111 vertical.

[0017] The tube 110 has a cylindrical interior cavity 112 extending along the entire length of the tube 110 and adapted to contain a flowing liquid, in particular a cooling fluid.

[0018] A tube such as tube 110 with air gap 112 can be manufactured relatively easily since it consists of two concentric cylindrical walls arranged concentrically. Each of the two walls usually has a constant diameter along its entire length, the difference between the two diameters of the two walls is small (e.g., the difference in diameters can be 20-60 mm), and the thickness of the two walls can be equal to each other and uniform everywhere (the thickness can be 3-10 mm). One can be called the "inner wall" (see element 116 in Figures 3 and 4). One can be called the "outer wall" (see element 115 in Figures 3 and 4). However, the manufacture of the two quartz walls is tricky, considering that the diameter of the tube is typically larger than, for example, 50 cm, and the height of the tube is typically larger than, for example, 100 cm.

[0019] The chamber 100 further comprises an annular closure element 120 made of quartz and fixed to the first lower end of the tube 110 to close the cavity 112 and prevent liquid from flowing out the bottom of the cavity.

[0020] The fixation between the tube 110 and the elements 120 is in particular carried out by welding and these welds (one of the elements 120 with the inner wall of the tube 110 and one of the elements 120 with the outer wall of the tube 110) must be carried out with care to avoid any risk of leakage of the liquid flowing in particular inside the chamber 100 and they are preferably made in areas of low thermal and low mechanical stresses.

[0021] At the top, the closure element 120 has an annular recess 122 facing the gap 112 so that the flowing liquid can reach the recess 122 at the bottom. Preferably, as shown in Figure 1, the width of the recess 122 corresponds to the width of the gap 112 where the closure element 120 is in contact with the tube 110. In fact, the gap 112 (which is filled with liquid during operation of the reactor) extends inside the element 120 according to a continuous surface (i.e. without steps).

[0022] In this way, any particular shape of the void (for mechanical and / or thermal and / or hydraulic reasons) is concentrated in the element 120 (and its recesses 122), which is also easier to manufacture and mechanically process due to the fact that it is small in size (much smaller than the tube 110). For example, its width can be 25-50 mm, its height can be 35-70 mm and its diameter is equal to that of the tube. See FIG. 2.

[0023] A particular configuration of element 120 is shown in FIG.

[0024] The radial cross-sectional profile of the recess 122 may include arcs with different radii, in particular a first radius (small, e.g. 5-15 mm) at the bottom 124 of the recess 122 and a second radius (large, e.g. 50-150 mm) at the sides 125, 126 of the recess 122, which is larger than the first radius. It should be noted that the radius of the side 125 may be the same or different from the radius of the side 126. In FIG. 2, the bottom 124 is diagrammatically distinguished from the sides 125 and 126 by two thin dashed line segments. The use of arcs with different radii allows optimal distribution and release of stresses due to the weight of the liquid in the voids of, for example, a cylindrical quartz tube, which in fact is usually large and vertically arranged, so that the total weight of the liquid is large.

[0025] The radial cross-sectional profile of the recess 122 can be such that the side 126 of the recess 122 and the side 125 of the recess end at different heights. In particular, the side 126 on a first side of the closure element 120 facing the axis 111 of the tube 110 ends at a higher height (e.g. 5-15 mm) relative to the side 125 on a second side of the closure element 120 opposite the first side of the closure element 120. The different heights facilitate the welding operation of the element 120 to the tube 110. The configuration of FIG. 2 is preferred since both welds can be performed externally by moving around the tube 110.

[0026] The closure element 120 can have a flange 123 in a second (lower) region of the closure element 120, not in contact with the tube 110, which advantageously projects radially. This flange is generally used for fastening quartz tubes. FIG. 2 shows diagrammatically the case where the flange 123 is clamped between the upper and lower elements, in particular thanks to its radial projection. FIG. 2 also shows several sealing gaskets (corresponding to the black circles in the figure). A gasket is placed between the upper element and the upper surface of the projection of the flange, and one or two gaskets are placed between the lower element and the bottom surface of the flange. Even though the element 120 is preferably made in one piece, in FIG. 2 the flange 123 is distinguished in the drawing from the rest of the element 120 by a thin dashed line segment.

[0027] An important aspect of the invention is the circulation of cooling liquid within the chamber, and more precisely within the peripheral wall of the chamber, as will be explained below, in particular the provision of a conduit within the gap which extends from a first lower region of the tube to a second upper region of the tube and which facilitates the circulation of the flowing liquid.

[0028] The tube 110 has a number of openings 113, 114 for the inlet and / or outlet of liquid flowing into and / or out of the cavity 112, and FIG. 1 indicates possible locations of the openings 113 and 114 by two dashed circles.

[0029] Preferably, the openings 113 and 114 can be arranged circumferentially on the outer surface of the tube 110 (as shown in FIG. 1). Preferably, the openings 113 and 114 can be arranged in a first lower region of the tube 110 (as shown in FIG. 1), and these openings can be at a certain distance (e.g., 10-50 mm) from the lower end of the tube. For example, there can be 3-10 openings 113, preferably equally spaced on a first circumference, and 3-10 openings 114, preferably equally spaced on a second circumference, where the first and second circumferences can be at the same height (as shown in FIGS. 3 and 4) or at slightly different heights, and the openings 113 and 114 can be arranged alternately around the tube 110.

[0030] In the illustrated example (particularly in Figures 3 and 4), a set of internal conduits 130 made of quartz inside the cavity 112 extends from openings 113 located in a first lower region of the tube 110 to a second upper region of the tube 110 (a part of the conduits 130 is outside the cavity due to the "L" shape of the conduits 130), a first set of the openings 113 (in the lower region of the tube) are adapted for liquid outlets and communicate with the set of internal conduits 130, and a second set of openings 114 (in the lower region of the tube) are adapted for liquid inlets. The cooling liquid enters the cavity 112 at the bottom (particularly through the conduits 140), flows upwards along the cavity 112, enters the internal conduits 130 at the top (in the far end region of the cavity 112), flows downwards along the internal conduits 130 and exits the internal conduits 130 at the bottom.

[0031] In the illustrated examples (particularly Figures 3 and 4), a set of external conduits 140 made of quartz that are external to the cavity 112 communicate with a second set of openings 114 (unlike Figure 4, portions of the conduits 140 may be internal to the cavity 112).

[0032] As can be seen from the figures, especially from figures 3 and 4, at the top the cavity 112 is closed by some closing element (which may correspond to the cover 160 shown in figure 1 or a special "plug"), with a free surface of the liquid being present slightly away from the closing element. Alternatively, the cavity may be open at the top. It is preferred that the cavity is closed by some closing element, especially to avoid evaporation of the liquid.

[0033] By way of example (by way of indication and not limitation), wall 115 has a thickness (typically uniform) of 4-6 mm, wall 116 has a thickness (typically uniform) of 4-6 mm, gap 112 has a width (typically uniform) of 15-30 mm, conduit 130 has a diameter (typically uniform) of 10-20 mm, they are equidistant from walls 115 and 116, and the upper end of conduit 130 is 20-50 mm from the upper ends of walls 115 and 116.

[0034] The circulation of the cooling liquid inside the peripheral wall of the chamber can also be performed in a manner different from that shown in Figures 3 and 4, for example as will be described below.

[0035] The tube may have a first set of openings (in the lower region of the tube) for incoming liquid inlet to the cavity, similar to openings 114 in the previous example.

[0036] Liquid enters the bottom of the cavity through this first set of openings, flows upward along the cavity, and exits at the top of the cavity.

[0037] This output may be in a "weir" fashion at the top edge of the tube 110, preferably at the top edge of the outer wall 115 (see FIG. 4), or it may be via a second set of openings, in which case the tube has a second set of openings (in an upper region of the tube) for liquid outlet from the void, the second set of openings may be located circumferentially on the outer surface of the tube, the second set of openings being located in a second upper region of the tube.

[0038] In both of these cases of an upper liquid outlet from the cavity, the walls of the tube are subjected to a greater pressure than in the case of a lower liquid outlet from the cavity (cases of figures 3 and 4).

[0039] In both of these cases of an upper liquid outlet coming out of the cavity, the pump circulating the liquid has to do more work than when the lower liquid outlet comes out of the cavity (as in Figures 3 and 4).

[0040] As previously mentioned, a reaction chamber such as chamber 100 is typically used in a reactor such as reactor 1000 of FIG.

[0041] A particularly advantageous application is as a reactor for growing silicon carbide ingots starting from a "seed" at very high temperatures, for example temperatures above 2000°C.

Claims

1. A reaction chamber (100) for a reactor (1000) for depositing a layer of semiconductor material on a substrate, comprising: a tube (110) made of quartz, having a cylindrical shape and adapted to be positioned in use with its axis (111) vertical, said tube (110) having a cylindrical internal cavity (112) extending along the entire length of the tube (110) and adapted to contain a flowing liquid; The device further comprises an annular closure element (120) made of quartz and fixed to the first lower end of the tube (110) to close the internal gap (112) and prevent liquid from flowing out of the lower part of the gap, the annular closure element (120) having an annular recess (122) at its upper part facing the internal gap (112) so that the flowing liquid can reach the recess (122) at the bottom; The tube (110) has a number of openings (113, 114) for the inlet and / or outlet of liquids entering and / or leaving the internal cavity (112), a set of internal conduits (130), preferably made of quartz, within said internal cavity (112), said internal conduits (130) extending upwardly from said plurality of openings (113) in a first lower region of said tube (110) to a second upper region inside said tube (110) and facilitating circulation of liquid flowing within said internal cavity (112); The liquid enters the interior of the tube (110) through the plurality of openings (114) at a first lower region of the tube (110), enters the internal conduit (130) at a second upper region inside the tube (110), and exits the internal conduit (130) at the first lower region of the tube (110); A reaction chamber (100) wherein a radial cross-sectional profile of the annular recess (122) terminates at different heights in a radial cross-section of the annular recess (122), a first side (126) of the annular recess (122) on an inner periphery of the tube (110) and a second side (125) of the annular recess (122) on an outer periphery of the tube (110).

2. 2. The reaction chamber (100) of claim 1, wherein a width of the annular recess (122) corresponds to a width of the internal gap (112) in a first region of the annular closure element (120) that contacts the tube (110).

3. 3. The reaction chamber (100) of claim 1 or claim 2, wherein the radial cross-sectional profile of the annular recess (122) comprises arcs having different radii, in particular an arc having a first radius at a bottom (124) of the annular recess (122) and a second radius at sides (125, 126) of the annular recess (122) that is greater than the first radius.

4. A reaction chamber (100) as described in claim 1, wherein a first side (126) of the annular recess (122) on a first side of the annular closure element (120) facing the axis (111) of the tube (110) terminates at a higher height relative to a second side (125) of the annular recess (122) on a second side of the annular closure element (120) opposite the first side of the annular closure element (120).

5. The reaction chamber (100) according to any one of claims 1 to 4, wherein the annular closure element (120) has a flange (123) in a second region of the annular closure element (120) that is not in contact with the tube (110).

6. The reaction chamber (100) according to any one of claims 1 to 5, wherein the openings (113, 114) are arranged circumferentially on an outer surface of the tube (110) in a first region of the tube at a height higher than a height of the annular closure element (120).

7. 7. The reaction chamber (100) of claim 6, wherein a first set of the plurality of openings (113) are adapted for outflow liquid outlets and communicate with the set of internal conduits (130), and a second set of the plurality of openings (114) are adapted for inflow liquid inlets.

8. 8. The method of claim 7, further comprising a set of external conduits (140) made of quartz outside the internal cavity (112), the second set of openings (114) communicating with the set of external conduits (140). A reaction chamber (100).

9. 6. The reaction chamber of claim 1, wherein the tube (110) has a first set of openings for incoming liquid inlet to the internal cavity (112), the first set of openings being circumferentially arranged on an outer surface of the tube (110), and the first set of openings being arranged in a first lower region of the tube.

10. A reaction chamber (100) for a reactor (1000) for depositing a layer of semiconductor material on a substrate, comprising: a tube (110) made of quartz, having a cylindrical shape and adapted to be positioned in use with its axis (111) vertical, said tube (110) having a cylindrical internal cavity (112) extending along the entire length of the tube (110) and adapted to contain a flowing liquid; The device further comprises an annular closure element (120) made of quartz and fixed to the first lower end of the tube (110) to close the internal gap (112) and prevent liquid from flowing out of the lower part of the gap, the annular closure element (120) having an annular recess (122) at its upper part facing the internal gap (112) so that the flowing liquid can reach the recess (122) at the bottom; The tube (110) has a first set of openings for inlet of incoming liquid into the internal cavity (112), the first set of openings being circumferentially disposed on an outer surface of the tube, the first set of openings being disposed in a first lower region of the tube. the tube has a second set of openings for exiting effluent liquid from the internal cavity (112), the second set of openings being circumferentially located on an outer surface of the tube, the second set of openings being disposed in a second upper region of the tube; a radial cross-sectional profile of the annular recess (122) such that a first side (126) of the annular recess (122) on an inner periphery of the tube (110) and a second side (125) of the annular recess (122) on an outer periphery of the tube (110) terminate at different heights in a radial cross-section of the annular recess (122).

11. A reactor (1000) comprising a reaction chamber (100) according to any one of the preceding claims.

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