SiC chemical vapor deposition device

Abstract

The present invention provides a SiC chemical vapor deposition apparatus comprising: a furnace body in which a deposition space is formed; and a mounting table which is located in the deposition space and on which a SiC wafer is mounted on a mounting surface, the furnace body having: a first hole which is located in an upper portion facing the mounting surface and which introduces a raw material gas into the deposition space; a second hole which is located in the side wall of the furnace body and through which a purge gas flows into the deposition space; and a third hole which is located below the second hole in the side wall of the furnace body and discharges the gas in the deposition space, the second hole being provided with a protrusion at the lower end thereof, the protrusion protruding toward the deposition space and adjusting the flow of the raw material gas.

Description

[0001] This application is a divisional application of the parent application filed by Risennoko Co., Ltd., entitled "SiC Chemical Vapor Deposition Apparatus" with application number "201911239990.3". Technical Field

[0002] This invention relates to SiC chemical vapor deposition apparatus.

[0003] This application claims priority under Japanese Patent Application No. 2018-239879, filed on December 21, 2018, the contents of which are incorporated herein by reference. Background Technology

[0004] Compared to silicon (Si), silicon carbide (SiC) possesses the following characteristics: an insulation breakdown electric field one order of magnitude larger, a band gap three times larger, and thermal conductivity approximately three times higher. These properties make silicon carbide a promising candidate for applications in power devices, high-frequency devices, and high-temperature operating devices. Therefore, in recent years, SiC epitaxial wafers have been used in such semiconductor devices.

[0005] For SiC epitaxial wafers, the substrate used for forming the SiC epitaxial film is typically a SiC single-crystal wafer (SiC wafer) processed from a bulk single crystal of SiC produced by methods such as sublimation. Specifically, a SiC epitaxial wafer is manufactured by growing a SiC epitaxial film, which forms the active region of the SiC semiconductor device, on the aforementioned substrate using chemical vapor deposition (CVD). Furthermore, in this specification, "SiC epitaxial wafer" refers to the wafer after the formation of the SiC epitaxial film. "SiC wafer" refers to the wafer before the formation of the SiC epitaxial film.

[0006] The performance of SiC semiconductor devices varies due to variations in the thickness, composition, and concentration of added impurities in the grown SiC epitaxial film. Therefore, it is required to form a uniform thin film on the substrate such as a SiC wafer.

[0007] In order to uniformly form a thin film on the substrate, it is important to uniformly supply the raw material gas relative to the substrate and suppress the formation of deposits such as defects on the wafer. Therefore, various studies have been conducted.

[0008] For example, Patent Document 1 describes a single-piece furnace-shaped CVD processing apparatus in which the raw material gas is supplied to the processing chamber in one pass and then uniformly supplied into the furnace via a spray member. It also describes a method for reducing dynamic pressure unevenness of the raw material gas introduced into the furnace from the spray member by making the inlet of the raw material gas toward the processing chamber conical in shape. The conical inlet reduces the flow rate of the raw material gas supplied into the processing chamber, suppressing pressure changes within the processing chamber. The CVD processing apparatus (chemical vapor deposition apparatus) described in Patent Document 1 is able to suppress pressure changes within the processing chamber.

[0009] Furthermore, Patent Document 2 also describes a SiC chemical vapor deposition apparatus with a tapered inlet for the gas inlet pipe that introduces the raw material gas into the furnace. The tapered gas inlet pipe suppresses convection near the inlet and prevents the re-attachment of deposits due to gas diffusion. If these deposits re-attach to the inlet pipe peel off and adhere to the wafer, they become a cause of wafer surface defects caused by particles. Devices formed on such surface defects become defective. Therefore, it is necessary to suppress wafer surface defects caused by particles.

[0010] Patent Document 1: Japanese Patent Application Publication No. 2009-74180

[0011] Patent Document 2: Japanese Patent Application Publication No. 2016-50164

[0012] The SiC chemical vapor deposition apparatus described in Patent Documents 1 and 2 achieves uniformity in the supply of raw material gas toward the workpiece by suppressing convection and dynamic pressure unevenness of the gas within the processing chamber. However, even under these conditions, gas flow within the processing chamber does not disappear, resulting in difficulties in supplying the raw material gas to the SiC wafer sufficiently and uniformly, and gas spreading toward the periphery of the sidewalls within the processing chamber. Summary of the Invention

[0013] The present invention was made in view of the above-mentioned situation, and its object is to provide a SiC chemical vapor deposition apparatus capable of uniformly supplying raw material gas to a SiC wafer.

[0014] The inventors of this invention conducted dedicated research and discovered that if there is a protrusion on the side wall of the furnace body that forms the deposition space, the raw material gas toward the SiC epitaxial film can be laminarized.

[0015] In other words, in order to solve the above-mentioned problems, the present invention provides the following solution.

[0016] (1) The SiC chemical vapor deposition apparatus according to the first method has: a furnace body that forms a deposition space inside; and a stage that is located in the deposition space and on which a SiC wafer is placed. The furnace body has: a first hole located above the stage opposite to the stage for introducing raw material gas into the deposition space; a second hole located on the side wall of the furnace body for allowing purge gas to flow into the deposition space; and a third hole located on the side wall of the furnace body below the second hole for discharging gas from the deposition space. The second hole has a protrusion at its lower end that protrudes toward the deposition space to adjust the flow of the raw material gas.

[0017] The SiC chemical vapor deposition apparatus of the first approach preferably includes the following features.

[0018] In addition, it is preferable that one or more of the following features are combined together.

[0019] (2) Alternatively, in the SiC chemical vapor deposition apparatus described above, the furnace body has a first part, a second part, and a third part from the top, the inner diameter of the first part is smaller than the inner diameter of the third part, the second part joins the first part and the third part, the first hole is located in the first part, the second hole and the protrusion are located in the second part, and the third hole is located in the third part.

[0020] (3) It can also be configured such that, in the SiC chemical vapor deposition apparatus involved in the above manner, the above-mentioned protrusion exists in a circular shape throughout the entire circumference of the side wall of the furnace body.

[0021] (4) It can also be configured such that, in the SiC chemical vapor deposition apparatus involved in the above manner, the protrusion is parallel to the mounting surface.

[0022] (5) It can also be configured such that, in the SiC chemical vapor deposition apparatus involved in the above manner, the protrusion is inclined upward from the side wall of the furnace body toward the deposition space relative to the mounting surface.

[0023] (6) It can also be configured such that, in the SiC chemical vapor deposition apparatus involved in the above manner, when the mounting surface is viewed from above, the first end of the protrusion is located at a position outside the outer periphery of the SiC wafer mounted on the mounting surface.

[0024] (7) It can also be configured such that, in the SiC chemical vapor deposition apparatus involved in the above manner, the second hole is located on the entire circumference of the side wall of the furnace body.

[0025] According to one embodiment of the present invention, a SiC chemical vapor deposition apparatus is capable of uniformly supplying raw material gas relative to a SiC wafer. Attached Figure Description

[0026] Figure 1 This is a cross-sectional schematic diagram of a preferred example of the SiC chemical vapor deposition apparatus involved in this embodiment.

[0027] Figure 2 This is a schematic cross-sectional view of an example of an existing SiC chemical vapor deposition apparatus.

[0028] Figure 3 This is a cross-sectional schematic diagram of a preferred example of the SiC chemical vapor deposition apparatus involved in this embodiment.

[0029] Figure 4 The icon represents the in-plane growth rate of the SiC epitaxial film in the SiC chemical vapor deposition apparatus of Example 1 and Comparative Example 1. Explanation of reference numerals in the attached figures

[0030] 1, 1', 100…SiC chemical vapor deposition apparatus; 2, 4, 102…furnace body; 4A…Part 1; 4B…Part 2; 4C…Part 3; 3…stage; 3A…mounting surface; 31…base; 32…heating mechanism; 21, 41…first hole; 22, 42…second hole; 23, 43…third hole; 24, 44…protrusion; 24a…first end on the film deposition space side; 25, 125…sidewall; 25A…upper sidewall; 25B…lower sidewall; 26…upper part; 27…bottom; L…inner diameter of the protrusion; R…deposition space; W…SiC wafer (wafer); G…raw material gas; p…purge gas; E1, E2…corners. Detailed Implementation

[0031] Hereinafter, an example of a SiC chemical vapor deposition apparatus to which the present invention is applied will be described in detail with appropriate reference to the accompanying drawings.

[0032] Furthermore, to facilitate understanding of the features of the present invention, the accompanying drawings used in the following description may be enlarged for convenience, and the dimensional ratios of various structural elements may differ from the actual dimensions. Additionally, the materials, dimensions, etc., exemplified in the following description are merely examples, and the present invention is not limited to them; appropriate modifications and implementations can be made without altering its spirit. That is, additions, omissions, substitutions, and changes can be made to the positions, quantities, shapes, materials, and structures without departing from the spirit of the present invention.

[0033] <SiC Chemical Vapor Deposition Apparatus>

[0034] Figure 1 This is a cross-sectional schematic diagram showing a preferred example of the SiC chemical vapor deposition apparatus 1 according to the first embodiment of the present invention.

[0035] The SiC chemical vapor deposition apparatus 1 according to this embodiment includes: a furnace body 2, which forms a deposition space R inside; and a stage 3, which is located in the deposition space R and holds a SiC wafer W.

[0036] Furthermore, in this embodiment, the direction in which the mounting platform 3 is arranged in the furnace body 2 is referred to as the downward direction, and the direction in which the first hole 21 is positioned relative to the mounting platform 3 (described later) is referred to as the upward direction.

[0037] (Platform)

[0038] The mounting stage 3 preferably includes, for example, a base 31 and a heating mechanism 32. The base 31 is a support for the SiC wafer W. The upper surface of the base 31 has a mounting surface 3A capable of holding the SiC wafer W. The base 31 has a tubular support shaft extending downwards. The support shaft can be connected, for example, to a rotating mechanism (not shown). The base 31 can be rotated by rotating the support shaft using the rotating mechanism. The heating mechanism 32 heats the SiC wafer W. The heating mechanism 32 can be, for example, disposed inside the base 31. The heating mechanism 32 can also be, for example, a heater positioned opposite the mounting surface of the SiC wafer W. The heating mechanism 32 passes through the interior of the support shaft and is energized from the outside.

[0039] (Furnace body)

[0040] The furnace body 2 has a deposition space R inside. Figure 1 The furnace body 2 shown has an upper part 26, side walls 25, and a bottom 27. The deposition space R is a space surrounded by the upper part 26, side walls 25, and bottom 27. The side walls 25 are composed of an upper side wall 25A and a lower side wall 25B.

[0041] The material of the furnace body 2 is not particularly limited, but it can be constructed by appropriately combining materials such as quartz, carbon, and SiC-coated carbon.

[0042] In addition, the furnace body 2 has a first hole 21, a second hole 22, and a third hole 23. The furnace body 2 has a protrusion 24 located below the second hole. The protrusion 24 is located directly below the second hole and above the third hole 23.

[0043] {Hole 1}

[0044] The first hole 21 is located opposite the mounting surface 3A of the stage 3, that is, above the mounting surface 3A. The first hole 21 is located, for example, on the upper surface of the furnace body 2, such as the upper part 26 of the furnace body 2. The number of first holes 21 can be arbitrarily selected as needed; for example, there can be one or more. The first hole 21 is a raw material gas inlet for introducing raw material gas G into the deposition space R. The raw material gas G supplied from the first hole 21 reacts on the SiC wafer W placed on the mounting surface 3A, forming a SiC epitaxial film on the SiC wafer W. The SiC epitaxial wafer film is manufactured by forming a SiC epitaxial film on the SiC wafer W. The raw material gas G, for example, uses known Si-based gases and C-based gases.

[0045] Examples of Si-based gases include silane (SiH4). In addition, Si-based gases can also be chlorine-based Si-containing raw material gases (chloride-based raw materials) containing Cl, such as SiH2Cl2, SiHCl3, and / or SiCl4, which have etching properties. Furthermore, Si-based gases can also be, for example, silanes with added HCl.

[0046] Examples of C-series gases include propane (C3H8).

[0047] In addition, to control the conductivity of the SiC epitaxial film stacked on the SiC wafer W, the impurity doping gas and the raw material gas G can be supplied simultaneously. For example, N2 is preferably used when the conductivity type is n-type, and TMA (trimethylaluminum) is preferably used when the conductivity type is p-type.

[0048] Si-based gases, C-based gases, and impurity-doped gases can be supplied separately or in combination.

[0049] The average flow rate (flow rate / cross-sectional area of ​​the first hole) of the feed gas G supplied from the first hole 21 into the deposition space R can be arbitrarily selected, but is preferably 0.001 m / s to 100 m / s, more preferably 0.005 m / s to 50 m / s, and even more preferably 0.01 m / s to 10 m / s.

[0050] {Second hole}

[0051] The second hole 22 is located on the side wall 25 of the furnace body 2. Figure 2 The second hole 22 shown is arranged around the entire circumference of the sidewall 25 of the furnace body 2. The second hole 22 separates the sidewall 25 into an upper sidewall 25A and a lower sidewall 25B. The second hole 22 introduces purge gas p into the deposition space R. The second hole 22 can also be a continuous single or multiple discontinuous annular holes when viewed from above. The upper sidewall 25A can also be combined with other components (not shown) around the furnace body 2.

[0052] The purge gas p is a gas that does not include Si and C. Purge gas p can be, for example, an inert gas (rare gas) such as Ar or He. The purge gas p is supplied to the periphery of the furnace body 2 to protect the insulation and heaters located around the furnace body 2. The purge gas p flows from the periphery of the furnace body 2 into the deposition space R.

[0053] {Third hole}

[0054] The third hole 23 is located on the side wall 25 of the furnace body 2. The third hole 23 is positioned below the mounting surface 3A in the mounting stage 3 within the furnace body 2. The third hole 23 serves as an exhaust port for venting gas from the deposition space R. For example, it vents unreacted gas and purge gas after passing through the SiC wafer W. The third hole 23 allows for vacuuming, enabling appropriate adjustment of the pressure inside the furnace body 2. While there may be only one third hole 23, multiple third holes 23 may be formed inside the furnace body 2 to improve the symmetry of the gas flow path and the in-plane uniformity of the epitaxial film.

[0055] {Protrusion}

[0056] The protrusion 24 is located at the lower end of the second hole 22. The protrusion 24 protrudes from the inner surface of the sidewall 25 toward the deposition space R. Figure 1 The protrusion 24 shown protrudes upwards at an angle relative to the mounting surface 3A from the side wall 25 of the furnace body 2 toward the center. Additionally, Figure 1 The protrusion 24 shown extends all around the circumference of the sidewall 25 and is arranged in a ring shape when viewed from above. The thickness of the protrusion 24 can also be fixed. The protrusion 24 controls the flow of the purge gas p flowing in from the second hole 22. The flow direction of the purge gas p is mainly along the direction of the protrusion 24. The flow of the purge gas p includes upward flow along the upper sidewall 25A. The purge gas p controls the flow of the feed gas G supplied from the first hole 21.

[0057] Alternatively, the protrusion 24 may also protrude upward from the side wall 25 of the furnace body 2 toward the deposition space R without tilting relative to the mounting surface 3A. For example, the protrusion 24 may also be parallel to the mounting surface 3A.

[0058] Regarding the orientation of the protrusion 24, it is preferable to set the angle θ of the protrusion 24 relative to the vertical direction to be 30° to 150°. From the viewpoint of causing the raw material gas to converge towards the center, it is more preferable that θ is 45° to 135°. From the viewpoint of suppressing the raw material gas G from flowing upward to the upper sidewall 25A due to convection, it is even more preferable that θ is 90° to 135°.

[0059] The first end 24a of the protrusion 24 on the film-forming space R side is preferably located, for example, on the outer side of the SiC wafer W placed on the mounting surface 3A when viewed from above. More preferably, the first end 24a of the protrusion 24 on the film-forming space R side is located on the outer side of the mounting surface 3A when viewed from above. The feed gas G flows from the first hole 21 toward the mounting stage 3. If the first end 24a of the protrusion 24 protrudes inwards from the outer side of the SiC wafer W, it may disrupt the flow of the feed gas G.

[0060] The size of the protrusion 24 can be appropriately selected to match the size of the wafer W placed on the mounting stage 3. The inner diameter of the protrusion 24 is appropriately selected to preferably control the flow path of the raw material gas. A smaller inner diameter of the protrusion 24 allows for effective concentration of the raw material gas in the center. Therefore, (inner diameter of the protrusion 24) ÷ (diameter of the wafer W) can be set to 4 or less, preferably 3 or less, and even more preferably 2 or less. The smaller the inner diameter of the protrusion 24, the stronger the effect of concentrating the gas in the center of the raw material gas; however, if the inner diameter of the protrusion 24 is too small, the gas will be too concentrated in the center, which is not preferable. Therefore, (inner diameter of the protrusion 24) ÷ (diameter of the wafer W) can be set to 1 / 2 or more, preferably 3 / 4 or more, and even more preferably 1 or more. By setting the inner diameter of the protrusion 24 within this range, the flow path of the raw material gas can be appropriately controlled. Here, the inner diameter of the protrusion 24 refers to the value obtained by subtracting the radial size of the protrusion 24 from the inner diameter of the furnace body. Figure 1 The distance L.

[0061] Figure 2 The existing SiC chemical vapor deposition apparatus 100 shown has a furnace body 2 and a mounting stage 3. Figure 2 The SiC chemical vapor deposition apparatus 100 shown is different from the one shown in that it does not have a second hole 22 and a protrusion 24. Figure 1 The SiC chemical vapor deposition apparatus shown is different from 1. Other structures are different. Figure 1 The SiC chemical vapor deposition apparatus shown is the same as 1, and the same reference numerals are used in the accompanying drawings, with descriptions omitted.

[0062] Figure 2 The SiC chemical vapor deposition apparatus 100 shown supplies a feed gas G from a first aperture 21. The feed gas G diffuses from the first aperture 21 toward the periphery of the sidewall 125. That is, the feed gas G diffuses upon reaching the SiC wafer W, making it impossible to effectively supply the feed gas G to the SiC wafer W.

[0063] In contrast, Figure 1The SiC chemical vapor deposition apparatus 1 shown in this embodiment is supplied with purge gas p, whose direction is controlled by the second orifice 22, into the deposition space R. The purge gas p will... Figure 2 In the SiC chemical vapor deposition apparatus 100 shown, the feed gas that expands to the periphery of the sidewall 125 converges to the vicinity of the center.

[0064] If the feed gas G is converged near the center of the deposition space R, the flow of the feed gas G is controlled in the vertical direction. Furthermore, in Figure 1 In the SiC chemical vapor deposition apparatus 1, the upper part 26 and the bottom part 27 are arranged horizontally.

[0065] Therefore, the vertical direction is perpendicular to the upper part 26 and the bottom part 27. That is, the flow of the feed gas G becomes laminar. If the composition of the feed gas G diffusing towards the sidewall 25 decreases, it becomes effective to supply the feed gas G to the SiC wafer W. In addition, the feed gas G can be supplied uniformly relative to the SiC wafer W.

[0066] Furthermore, the purge gas p is an inert gas, so it will not react with the raw material gas G inside the furnace body 2 to produce deposits. Therefore, the purge gas p flows along the side wall 25 of the furnace body 2, thereby suppressing the formation of deposits on the side wall 25 of the furnace body 2 caused by the raw material gas.

[0067] Usually, in Figure 1 , Figure 2 As shown, the SiC wafer W is located in the SiC chemical vapor deposition apparatus 1, 100 at the bottom of the furnace, where the temperature near the SiC wafer W becomes the highest. As a result, a thermal gradient exists within the furnace bodies 2, 102. Due to the thermal gradient within the furnace bodies 2, 102, convection occurs based on the feed gas G that arrives near the SiC wafer W at once.

[0068] exist Figure 2 In the SiC chemical vapor deposition apparatus 100 shown, the feed gas G, which does not contribute to the growth of SiC epitaxial films, flows upwards towards the sidewall 125 due to convection. Furthermore, the feed gas G adheres to the upper surface of the sidewall 125 within the furnace body 102. Deposits are formed inside the furnace body 102 due to the adhesion of the feed gas G.

[0069] Deposits are one of the causes of grain formation on SiC epitaxial wafers. Particles adhering to the surface of the substrate become a cause of crystallization defects.

[0070] The protrusion 24 also suppresses the upward convection of the raw material gas G. Therefore, it is possible to suppress the formation of deposits on the upper sidewall 25A of the furnace body 2. If the deposits that cause particulate matter are reduced, the quality of the SiC epitaxial wafer is improved.

[0071] The average flow velocity of the purge gas flowing into the deposition space R can be arbitrarily selected, but (flow rate / cross-sectional area of ​​the second orifice) is, for example, 0.1 m / s to 100 m / s. The average flow velocity of the purge gas p is preferably 0.2 m / s to 50 m / s, more preferably 0.5 m / s to 30 m / s.

[0072] In the SiC chemical vapor deposition apparatus 1 according to this embodiment, the flow of the raw material gas G is controlled by the inert purge gas p, whose direction is controlled by the protrusion 24. Therefore, the supply of the raw material gas G toward the SiC wafer W can be effectively achieved. In addition, the purge gas p also suppresses deposits from adhering to the upper sidewall 25A.

[0073] The first embodiment has been described in detail above, but the SiC chemical vapor deposition apparatus involved in the first embodiment is not limited to this example, and various modifications and alterations can be made within the scope of the spirit of the present invention as described in the claims.

[0074] For example, the second hole 22 can be a continuous opening covering the entire circumference of the side wall 25 of the furnace body 2, or it can be multiple openings that are not connected to each other. When the second hole 22 is a continuous opening covering the entire circumference of the side wall 25 of the furnace body 2, for example, the upper part of the furnace body 2 (the combination of the upper part 26 and the upper side wall 25A) can be suspended by a support member (not shown), and the lower part of the furnace body 2 (the combination of the lower side wall 25B and the bottom 27) can be placed on a mounting member (not shown). As a result, the upper and lower parts of the furnace body 2 can also be held at a fixed interval. When the second hole 22 is multiple openings, the number of second holes 22 for introducing purge gas p is not particularly limited, but a larger number is preferred.

[0075] Hereinafter, examples of multiple openings for the second hole 22 will be described. Furthermore, from the viewpoint of the symmetry of the gas flow path, the second holes 22 are preferably positioned at equal intervals.

[0076] While the size and shape of the second hole 22 are not particularly limited, it can be, for example, a quadrilateral, approximately quadrilateral, rectangular, or circular opening on the side. The second hole 22 can be provided at equal intervals or in a prescribed configuration as needed, for example, it can be configured to appear as a ring when viewed from above. The second hole 22 can also appear as a discontinuous ring when viewed from above. It can also be a ring-shaped hole whose vertical height changes from the outside to the inside of the furnace and whose upper and lower surfaces are curved. The height of the second hole 22 can be, for example, 1 mm or more. More preferably, it can be 1.5 mm or more, and even more preferably, it can be 2 mm or more. Furthermore, the height of the second hole 22 can be, for example, 100 mm or less. More preferably, it can be 50 mm or less, and even more preferably, it can be 30 mm or less. When the second hole 22 is arranged in a ring shape, the width and length of the ring can be appropriately selected. Additionally, the circumferential opening ratio of the second hole 22 can be 1 (100%), preferably close to 1. To control the flow of the raw material gas G, the circumferential opening ratio based on the second hole 22 is 0.3 or higher. Here, the circumferential opening ratio based on the second hole 22 refers to the opening ratio of the furnace body 2 at the vertical height where the second hole 22 is located. For example, when the height of the second hole is the same, an opening ratio of 1 means that the second hole is open throughout the entire circumference, while an opening ratio of 0.5 means that the second hole is open with 50% of its volume compared to an opening ratio of 1.

[0077] The height at which the second hole 22 is positioned is preferably higher than that of the mounting surface 3A.

[0078] The protrusion 24 may not be a continuous annular component extending throughout the sidewall 25. The protrusion 24 may also be multiple components arranged relative to the second hole 22. If the protrusion 24 exists throughout the entire circumference of the sidewall 25, the raw material gas G can converge toward the center of the furnace body 2 at any circumferential position within the furnace body 2, thereby preventing the raw material gas G from rolling up the upper sidewall 25A.

[0079] When the protrusion 24 is composed of multiple components, the number of protrusions 24 is not particularly limited, but a larger number is preferred. The aforementioned multiple components can be arranged at the same height on the sidewall 25.

[0080] (Second Implementation)

[0081] Figure 3 This is a cross-sectional schematic diagram showing a preferred example of the SiC chemical vapor deposition apparatus 1' according to the second embodiment. The structure of the furnace body 4 of the SiC chemical vapor deposition apparatus 1' according to the second embodiment differs from that of the SiC chemical vapor deposition apparatus 1 according to the first embodiment. Other structures are the same, and the same reference numerals are used, with descriptions omitted.

[0082] Figure 3 The chemical vapor deposition apparatus 1' shown has a furnace body 4 with a first part 4A, a second part 4B, and a third part 4C, starting from the top. The inner diameter of the first part 4A is smaller than the inner diameter of the third part 4C. Here, "inner diameter" refers to the diameter of the inner surface of the furnace body 4 on the film-forming space R side when the furnace body 4 is cut horizontally. The second part 4B is the portion that connects the first part 4A and the third part 4C.

[0083] Corners E1 and E2 are formed at the connection points of Part 1 4A and Part 2 4B, and at the connection points of Part 2 4B and Part 3 4C, respectively. Corner E1, which protrudes towards the inside of the film-forming space R, is the part where deposits easily adhere.

[0084] Additionally, the furnace body 4 has a first hole 41, a second hole 42, a third hole 43, and a protrusion 44. Raw material gas G is supplied through the first hole 41, purge gas p is supplied through the second hole 42, and gas within the film-forming space R is discharged through the third hole 43. The first hole 41 is located in the first part 4A, the second hole 42 is located in the second part 4B, and the third hole 43 is located in the third part 4C. If the inner diameter of the first part 4A of the furnace body 4 is smaller than the inner diameter of the third part 4C, the raw material gas G is less likely to diffuse around the periphery of the first part. Therefore, the furnace body 4 easily concentrates the raw material gas near the center. Furthermore, the furnace body 4 suppresses the amount of raw material gas flowing upwards due to convection.

[0085] The purge gas p flows in through the second hole 42. The direction of the purge gas p is controlled by the protrusion 44, thereby suppressing the upward convection of the feed gas G. As described above, the corner E1 is a region where deposits easily adhere. The peeling off of deposits attached to this region is the cause of particle formation. If the deposits that cause particles are reduced, the quality of the SiC epitaxial wafer is improved.

[0086] In the furnace body 4, the specific structures of the first hole 41, the second hole 42, the third hole 43, and the protrusion 44 can be the same as those of the first hole 21, the second hole 22, the third hole 23, and the protrusion 24 in the furnace body 2. Furthermore, the orientation of the protrusion 44 is also the same as that of the protrusion 24.

[0087] That is, the angle θ of the protrusion 44 relative to the vertical direction is the same as the angle θ of the protrusion 24 relative to the vertical direction.

[0088] Example

[0089] (Example 1)

[0090] Through simulation reproduction Figure 3Using the chemical vapor deposition apparatus 1' with the structure shown, the growth rate of the SiC epitaxial film was determined. Fluent from ANSYS was used in the simulation. The simulation was confirmed to have a high correlation with actual experimental results.

[0091] The specific conditions for the simulation are as follows.

[0092] Temperature of furnace wall 2: Above 1400℃

[0093] Temperature of wafer W: around 1600℃

[0094] Purge gas flow rate (p) / feed gas flow rate (G): 1.3

[0095] Maximum flow velocity of raw gas: approximately 20 m / s

[0096] The protruding direction of the protrusion 44 is parallel to the mounting surface 3A of the mounting platform 3.

[0097] Diameter of wafer W: 200mm

[0098] The inner diameter L of protrusion 44 / wafer diameter: 1.4

[0099] Inner radius of the protrusion / vertical height of the protrusion 44 from the mounting platform 3: 4.2

[0100] The circumferential opening ratio of the second hole 22 is 100%.

[0101] (Comparative Example 1)

[0102] Comparative Example 1 differs from Example 1 in that it does not have the protrusion 44. All other conditions are the same as in Example 1.

[0103] Figure 4 This is a graph representing the in-plane growth rate of SiC epitaxial wafers grown under the conditions of Example 1 and Comparative Example 1. The horizontal axis represents the distance from the measurement point to the center of the SiC wafer W, and the vertical axis represents the growth rate of the SiC epitaxial film at the measurement point. Figure 4As shown, in Comparative Example 1, the growth rate of the SiC epitaxial film slows down on the outer side of the SiC wafer W. In contrast, the growth rate of the SiC epitaxial film in Example 1 is almost uniform within the plane of the SiC wafer W. The uniformity index of the SiC epitaxial film is, for example, the value of 100 × {100 - (minimum growth rate)} ÷ (maximum growth rate), and it can be said that the lower this value, the higher the uniformity of the SiC epitaxial film. In Example 1 and Comparative Example 1, which are calculation results relative to a wafer with a radius of 100 mm, this value is 17.9% and 25.5%, respectively. Based on this result, it can be said that the uniformity of the SiC epitaxial film under the conditions of Example 1 is higher than that under the conditions of Comparative Example 1. That is, the protrusion 44 is due to the improved uniformity of the carrier concentration of the SiC epitaxial film and the effective growth of the SiC epitaxial film.

[0104] Industrial applicability

[0105] As described above, the SiC chemical vapor deposition apparatus of the present invention is useful for improving the uniformity of carrier concentration within the wafer plane and manufacturing high-quality SiC epitaxial wafers by having holes for supplying purge gas to the side wall of the furnace body and protrusions for adjusting the gas flow path within the furnace body.

[0106] A SiC chemical vapor deposition apparatus is provided that can uniformly supply raw material gas to a SiC wafer placed on a mounting stage.

Claims

1. A SiC chemical vapor deposition apparatus, wherein, have: The furnace body, which forms a deposition space inside; and A mounting stage is located within the deposition space, and a SiC wafer is mounted on the mounting surface. The furnace body has: The first hole, located on the upper part of the furnace body facing the mounting surface, introduces the raw material gas for forming SiC epitaxial film into the deposition space; A second hole, located on the side wall of the furnace body, allows purge gas to flow into the deposition space. This purge gas does not contain the raw material gas used to form the SiC epitaxial film, but is composed of an inert gas. The third hole, located on the side wall of the furnace body below the second hole, discharges the gas from the deposition space. The lower end of the second hole has a protrusion that protrudes toward the deposition space to adjust the flow of the raw material gas. The protrusion is located directly below the second hole. The second hole is provided all around the circumference of the side wall of the furnace body. The protrusions are present in a circular shape around the entire circumference of the side wall of the furnace body. The SiC chemical vapor deposition apparatus has the capability to heat the SiC wafer to 1600°C.

2. The SiC chemical vapor deposition apparatus according to claim 1, wherein, The furnace body is divided into three parts, namely, Part 1, Part 2, and Part 3, starting from the top. The inner diameter of the first part is smaller than the inner diameter of the third part. The second part joins the first part with the third part. The first hole is located in the first part. The second hole and the protrusion are located in the second part. The third hole is located in the third part.

3. The SiC chemical vapor deposition apparatus according to claim 1, wherein, The angle of the protrusion relative to the vertical direction from top to bottom is 30° to 150°.

4. The SiC chemical vapor deposition apparatus according to claim 1, wherein, The protrusion is parallel to the mounting surface.

5. The SiC chemical vapor deposition apparatus according to claim 1, wherein, The protrusion extends from the side wall of the furnace body toward the deposition space and slopes upward relative to the mounting surface.

6. The SiC chemical vapor deposition apparatus according to claim 1, wherein, When viewed from above, the first end of the protrusion on the film-forming space side is located on the outer side of the SiC wafer placed on the mounting surface.

7. The SiC chemical vapor deposition apparatus according to claim 1, wherein, The average flow velocity of the purge gas flowing into the deposition space is 0.1 m / s to 100 m / s.

8. The SiC chemical vapor deposition apparatus according to claim 1, wherein, The inner diameter of the protrusion divided by the diameter of the SiC wafer is more than 1 / 2 and less than 4.

9. The SiC chemical vapor deposition apparatus according to claim 1, wherein, The height of the second hole is more than 1 mm and less than 100 mm.

10. The SiC chemical vapor deposition apparatus according to claim 1, wherein, The circumferential opening ratio of the second hole at the vertical height where the second hole of the furnace body is located is 0.3 or more and 1 or less.

11. The SiC chemical vapor deposition apparatus according to claim 2, wherein, Corner portions are formed at the connection points of the first part and the second part, and at the connection points of the second part and the third part.

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