Wafer support boat, horizontal heat treatment furnace, heat treatment method of wafer, and manufacturing method of bonded wafer

Abstract

The present invention provides a wafer support boat capable of suppressing occurrence of various undercuts, a horizontal heat treatment furnace having the wafer support boat, a heat treatment method of a wafer using the wafer support boat, and a manufacturing method of a bonded wafer. The wafer support boat of the present invention is a wafer support boat for a horizontal heat treatment furnace. A housing portion is made of silicon carbide, and a support portion is made of quartz. The horizontal heat treatment furnace of the present invention has the wafer support boat. The heat treatment method of a wafer of the present invention includes a heat treatment step of heat treatment using the wafer support boat. The manufacturing method of a bonded wafer of the present invention includes a heat treatment step based on the heat treatment method of a wafer.

Description

TECHNICAL FIELD

[0001] The present application relates to a wafer supporting boat for a horizontal heat treatment furnace, a horizontal heat treatment furnace provided with the wafer supporting boat, a heat treatment method of a wafer using the wafer supporting boat, and a manufacturing method of a bonded wafer. BACKGROUND

[0002] Conventionally, a method of heat treating a wafer using a horizontal heat treatment furnace is known, the aforementioned horizontal heat treatment furnace being provided with a core tube and a wafer supporting boat, the aforementioned core tube extending horizontally inside a furnace main body, and the aforementioned wafer supporting boat being capable of placing a plurality of wafers (for example, Patent Document 1).

[0003] Here, a silicon on insulator (SOI) wafer has a structure in which an insulating film such as silicon oxide (SiO2) and a single-crystal silicon layer serving as an active layer of a device are sequentially formed on a supporting substrate wafer. One of representative manufacturing methods of a silicon on insulator wafer is a bonding method. The bonding method forms an oxide film as a buried oxide (BOX) layer on at least one of a supporting substrate wafer and an active layer wafer, and then bonds the supporting substrate wafer and the active layer wafer via the oxide film to constitute a bonded wafer. Furthermore, heat treatment for firmly joining the supporting substrate wafer and the active layer wafer is performed on the bonded wafer, thereby manufacturing a silicon on insulator wafer.

[0004] FIG. 1A is a schematic front view of a conventional wafer supporting boat, FIG. 1B is a schematic side view of the conventional wafer supporting boat. Among all the processes, as a process of performing heat treatment, there are a buried oxide (BOX) oxide film heat treatment process and a post-bonding heat treatment process performed after bonding.

[0005] First, an active layer wafer and a supporting substrate wafer are prepared. Then, a buried oxide heat treatment process of forming an oxide film on the active layer wafer is performed. In the buried oxide heat treatment process, as shown in FIG. 1A , FIG. 1B , a wafer supporting boat on which a silicon wafer for an active layer is placed is put into a heat treatment furnace, and thereby the active layer wafer is heat treated in an oxidizing atmosphere to form an oxide film on the active layer wafer.

[0006] Here, the wafer supporting boat is a wafer supporting boat in which a plurality of wafers are arranged at equal intervals in the horizontal direction and each wafer stands in the vertical direction (for example, Patent Document 2). As shown in FIG. 1A , FIG. 1B , a plurality of wafer grooves 92 are provided at equal intervals in the horizontal direction at the wafer supporting boat 91. In addition, as shown in FIG. 1A , FIG. 1BFor simplicity, only one wafer W is represented, but in reality, multiple wafers W are placed in each of multiple wafer slots 92.

[0007] Next, the active layer wafer and the support substrate wafer are bonded together via a buried oxide layer. The active layer wafer and the support substrate wafer are aligned at the groove and bonded in a manner that prevents air, foreign matter, etc. from entering the bonding interface between the active layer wafer and the support substrate wafer.

[0008] Next, to improve the bonding strength, a post-bonding heat treatment is performed. This heat treatment involves placing the wafer W (with the active layer wafer and the support substrate wafer bonded together) in the wafer groove 92 of the wafer support boat 91, and then immersing the wafer support boat 91 together in a heat treatment furnace for heat treatment in an oxidizing atmosphere. Afterwards, the wafer support boat 91 is removed from the heat treatment furnace, and subsequently, the wafer W is removed from the wafer support boat 91.

[0009] Subsequently, relative to the active layer wafer, chamfering, etching, grinding and polishing processes are performed to process the thickness of the active layer wafer to a predetermined thickness, thus creating a silicon-on-insulator wafer.

[0010] Patent document 1: Japanese Patent Application Publication No. 2021-089993.

[0011] Patent document 2: Japanese Patent Application Publication No. 2002-299423.

[0012] Traditionally, wafer support boats have been constructed entirely of silicon carbide (SiC). This is because, in the buried oxide heat treatment process for forming the buried oxide layer, given the typical heat treatment temperatures and times, a heat-resistant material that is resistant to thermal deformation is preferred. Furthermore, the post-lamination heat treatment process also requires prolonged heat treatment at high temperatures, and the wafer support ports need to support the weight of the two laminated wafers, thus requiring high heat resistance and load-bearing capacity. As a material possessing these properties, silicon carbide is frequently chosen as the material for wafer support boats.

[0013] However, using silicon carbide wafer support boats for heat treatment has the following problems. FIGS. 2A-2D This diagram illustrates the heat treatment and bonding of buried oxides using conventional wafer support boats.

[0014] In the buried oxide oxidation process, there are cases where an oxide film Wa generated on the surface of a silicon wafer W through heat treatment and an oxide film 91a generated on the surface of a silicon carbide wafer support boat 91 are bonded together. FIG. 2A At this point, when the silicon wafer W is removed from the silicon carbide wafer support boat 91, there is a situation where a portion of the oxide film is missing due to the fixing of the wafer end face to the silicon carbide wafer boat 91, resulting in a silicon wafer Wb. FIG. 2B). In addition, there is a case where a wafer Wb lacking in the buried oxide is left in the wafer groove 92 of the wafer support boat 91, and the wafer Wb left in the wafer groove 92 is heat-treated while a wafer W of the next batch for heat treatment is loaded thereon, so that the end face of the wafer is also likely to be defective. In addition, the wafer is also attached to the wafer surface FIG. 2C ), and is also likely to be defective in the hillock. In particular, there is a tendency that the thicker the film thickness of the buried oxide, the more the above phenomenon is likely to occur, the higher the defective rate of the hillock, and the higher the defective rate of the end face.

[0015] In addition, in the heat treatment process after the bonding, there is a case where a defect occurs in the portion of the end face of the wafer for the active layer and the wafer for the support substrate, which is fixed to the wafer support boat. In addition, in the state where the oxide is defective in the end face, when etching is performed in the subsequent process, a hole is likely to be generated in the end face of the silicon wafer to become defective.

[0016] Further, in the bonding process, the wafer Wb attached to the wafer surface during the heat treatment of the buried oxide is sandwiched between the wafers for the support substrate, and the wafer is sandwiched at the interface between the two wafers, so that a defective bonding is likely to occur FIG. 2D ). In addition, the wafer is also sandwiched at the interface between the wafers, which causes air to enter the interface between the wafers.

[0017] In the bonding process and the heat treatment process after the bonding, in particular, there is a tendency that the thicker the film thickness of the buried oxide, the more the above phenomenon is likely to occur, and the higher the defective rate. SUMMARY

[0018] In view of the above problems, an object of the present application is to provide a wafer support boat capable of suppressing the occurrence of the above various defects, a horizontal heat treatment furnace having the wafer support boat, a heat treatment method of a wafer using the wafer support boat, and a manufacturing method of a bonded wafer.

[0019] The main aspect of the present application is described below.

[0020] (1) A wafer support boat for a horizontal heat treatment furnace, characterized by comprising a housing portion for housing a wafer, and a support portion for supporting the wafer disposed at the bottom of the housing portion, the support portion having a support portion main body extending in the direction of wafer arrangement, and a plurality of protruding portions protruding upward from the support portion main body and arranged in the direction extending from the support portion main body, a wafer groove for arranging a wafer being formed by the space between two adjacent protruding portions, the housing portion being composed of silicon carbide, and the support portion being composed of quartz.

[0021] (2) The wafer support boat according to the above (1), characterized in that the thickness of the support portion main body is 2 to 30 mm.

[0022] (3) The wafer support boat according to any one of (1) or (2), wherein the bottom portion of the housing portion supports the support portion main body by surface support.

[0023] (4) The wafer support boat according to any one of (1) or (2), wherein the bottom portion of the housing portion supports the support portion main body by point support based on a plurality of portions.

[0024] (5) The wafer support boat according to any one of (1) to (4), wherein the support portion is detachably attached to the housing portion.

[0025] (6) A horizontal heat treatment furnace comprising the wafer support boat according to any one of (1) to (5).

[0026] (7) A heat treatment method of a wafer, comprising a heat treatment step of heat treating a wafer using the wafer support boat according to any one of (1) to (5).

[0027] (8) A method of manufacturing a bonded wafer, comprising a heat treatment step based on the heat treatment method of a wafer according to (7).

[0028] (9) The method of manufacturing a bonded wafer according to (7), wherein at least one of a buried oxide heat treatment step and a post-bonding heat treatment step is performed as the heat treatment step.

[0029] Effects of Invention

[0030] According to the present application, it is possible to provide a wafer support boat capable of suppressing occurrence of various undercuts described above, a horizontal heat treatment furnace having the wafer support boat, a heat treatment method of a wafer using the wafer support boat, and a method of manufacturing a bonded wafer. BRIEF DESCRIPTION OF DRAWINGS

[0031] FIG. 1A is a schematic front view of a conventional wafer support boat.

[0032] FIG. 1B is a schematic side view of a conventional wafer support boat.

[0033] FIG. 2A is a diagram for explaining a buried oxide heat treatment and bonding using a conventional wafer support boat.

[0034] FIG. 2B is a diagram for explaining a buried oxide heat treatment and bonding using a conventional wafer support boat.

[0035] FIG. 2Cis a view for explaining a buried oxide heat treatment and a bonding using a conventional wafer supporting boat.

[0036] FIG. 2D is a view for explaining a buried oxide heat treatment and a bonding using a conventional wafer supporting boat.

[0037] FIG. 3A is a schematic front view of a wafer supporting boat of an embodiment of the present application on which one wafer is placed.

[0038] FIG. 3B is a schematic side view of a wafer supporting boat of an embodiment of the present application on which one wafer is placed.

[0039] FIG. 3C is a schematic plan view of a wafer supporting boat of an embodiment of the present application.

[0040] FIG. 4A is a view schematically showing a state before a heat treatment of a conventional wafer supporting boat made of silicon carbide.

[0041] FIG. 4B is a view schematically showing a state after a heat treatment of a conventional wafer supporting boat made of silicon carbide.

[0042] FIG. 5A is a view schematically showing a state before a heat treatment of a case where quartz is used for a wafer supporting portion.

[0043] FIG. 5B is a view schematically showing a state after a heat treatment of a case where quartz is used for a wafer supporting portion.

[0044] FIG. 6A is a schematic plan view of a wafer supporting boat of a modification of an embodiment of the present application on which one wafer is placed.

[0045] FIG. 6B is a schematic side view of a wafer supporting boat of a modification of an embodiment of the present application on which one wafer is placed.

[0046] FIG. 7 is a view for explaining a thickness of a supporting portion main body.

[0047] FIG. 8A is a view showing a surface support of the supporting portion main body by a bottom portion of a housing portion.

[0048] FIG. 8B is a view showing a point support of the supporting portion main body by a bottom portion of a housing portion.

[0049] FIG. 9 is a sectional view of a horizontal heat treatment furnace of an embodiment of the present application.

[0050] FIG. 10A is a view showing each step of a manufacturing method of a bonded wafer of an embodiment of the present application.

[0051] FIG. 10B is a view showing each step of a manufacturing method of a bonded wafer of an embodiment of the present application.

[0052] FIG. 10C is a view showing each step of a manufacturing method of a bonded wafer of an embodiment of the present application.

[0053] FIG. 10D is a view showing each step of a manufacturing method of a bonded wafer of an embodiment of the present application.

[0054] FIG. 10E is a view showing each step of a manufacturing method of a bonded wafer of an embodiment of the present application.

[0055] FIG. 10F is a view showing each step of a manufacturing method of a bonded wafer of an embodiment of the present application.

[0056] FIG. 10G is a view showing each step of a manufacturing method of a bonded wafer of an embodiment of the present application.

[0057] FIG. 10H is a view showing each step of a manufacturing method of a bonded wafer of an embodiment of the present application.

[0058] FIG. 11A is a view showing the result of quality evaluation of a wafer end surface of a comparative example.

[0059] FIG. 11B is a view showing the result of quality evaluation of a wafer end surface of an inventive example.

[0060] FIG. 12A is a view showing the result of luminescent point observation of a wafer surface of a comparative example.

[0061] FIG. 12B is a view showing the result of luminescent point observation of a wafer surface of an inventive example. DETAILED DESCRIPTION

[0062] Hereinafter, an embodiment of the present application will be described in detail with reference to the drawings.

[0063] (Wafer support boat)

[0064] FIG. 3A is a view showing each step of a manufacturing method of a bonded wafer of an embodiment of the present application. FIG. 3B is a view showing each step of a manufacturing method of a bonded wafer of an embodiment of the present application. FIG. 3Cis a schematic plan view of a wafer support boat on which an embodiment of the present application is mounted.

[0065] The wafer support boat 1 of the present embodiment is a wafer support boat for a horizontal heat treatment furnace, configured to arrange a plurality of wafers W (silicon wafers in this example) in one direction in the horizontal direction, and capable of heat treating the plurality of wafers W simultaneously.

[0066] As shown in FIGS. 3A-3C , the wafer support boat 1 has a housing portion 2 and a support portion 3.

[0067] In the following description, the direction perpendicular to the paper of the FIG. 3A is set as the front-rear direction, the left-right direction on the paper is set as the lateral direction, and the up-down direction on the paper is set as the vertical direction.

[0068] The housing portion 2 has a bottom portion 21, a side portion 22 joined to the bottom portion 21 and extending upward in the vertical direction, and an upper portion 23 joined to the side portion 22 and extending in the lateral direction.

[0069] In the illustrated example, the bottom portion 21 is one plate-shaped member extending in the lateral direction. Further, the side portion 22 is composed of two plate-shaped members in a substantially U shape as shown in FIG. 3B . The upper portion 23 is joined to the upper end of the side portion 22 and is composed of two plate-shaped members extending in the lateral direction. A plurality of wafer grooves 231 for the wafers W to enter are provided in the upper portion 23, and the plurality of wafer grooves 231 are arranged in the lateral direction.

[0070] Next, the support portion 3 is disposed on the upper surface of the bottom portion 21 of the housing portion 2 and is configured to support the wafers. The support portion 3 is detachably attached with respect to the housing portion 2.

[0071] The support portion 3 has a support portion main body 31 extending in the direction in which the wafers are arranged (the lateral direction of the FIG. 3A ), and a plurality of protruding portions 32 arranged in the direction in which the support portion main body 31 extends upward. Further, the wafer grooves 33 in which the wafers W are disposed are partitioned by the two adjacent protruding portions 32. In the illustrated example, the wafer grooves 33 are arranged in the lateral direction. The protruding portions 32 are configured to be able to support the lower side surfaces of the wafers W.

[0072] Here, in the present embodiment, the entire housing portion 21 is composed of silicon carbide, and the support portion 3 is composed of quartz.

[0073] Next, the effects of the wafer support boat of the present embodiment will be described.

[0074] FIG. 4A is a diagram schematically showing the state before heat treatment of a conventional wafer support boat made of silicon carbide. FIG. 4Bis a diagram schematically showing a case where a conventional silicon carbide-made wafer support boat is heat-treated. FIG. 5A is a diagram schematically showing a case where a wafer support portion is made of quartz before heat treatment. FIG. 5B is a diagram schematically showing a case where a wafer support portion is made of quartz after heat treatment.

[0075] If a silicon wafer is heat-treated in an oxygen atmosphere, Si on the surface of the silicon wafer reacts with O2 in the atmosphere to form an oxide film. Furthermore, O2 diffuses into the oxide film growing at the silicon surface to further form an oxide film (SiO2) by reacting with Si at the interface between the oxide film and the silicon.

[0076] As shown in FIG. 4A , FIG. 4B , in a case where the support portion (support portion main body 131 and protruding portion 132) is a silicon carbide member, Si on the surface of the silicon carbide member reacts with O2 in the atmosphere to form a thermal oxide film. Furthermore, O2 diffuses into the oxide film growing at the silicon surface to further form an oxide film (SiO2) as indicated by the diagonal line in FIG. 4B . Thus, in the silicon carbide-made wafer support boat, the oxide film of both the silicon carbide member and the silicon wafer is growing at the portion where they are in contact with each other, and the oxide film on the wafer side and the oxide film on the wafer support boat side are combined.

[0077] On the other hand, as shown in FIG. 5A , FIG. 5B , in a case where the support portion (support portion main body 31 and protruding portion 32) is a quartz (SiO2) member, SiO2 members do not have Si that combines even if O2 diffuses into the SiO2. Thus, in the quartz-made wafer support boat, the oxide film on the wafer side is growing, and an oxide film (SiO2) is formed as indicated by the diagonal line in FIG. 5B , but no oxide film is formed on the wafer support boat side, so no combination of the oxide films occurs.

[0078] In the present embodiment, first, the accommodation portion 2 is made of silicon carbide, so the heat resistance and load resistance of the wafer support boat 1 as a whole are excellent.

[0079] On the other hand, the support portion 3 that supports the load of the silicon wafer W is made of quartz, so as described above, the oxide bonding of the silicon wafer and the wafer support boat can be suppressed. Even if high-temperature and long-time heat treatment (for example, oxidation treatment in which the oxide film is 1 μm or more thick) is performed in a buried oxide heat treatment process, a post-bonding heat treatment process, or the like, the oxide bonding of the silicon wafer W and the wafer support boat 1 can be suppressed.

[0080] Therefore, when the silicon wafers W are taken out from the silicon wafer support boat 1 after the oxidation heat treatment, it is possible to suppress the occurrence of damage and defects on the end surface of the silicon wafer W, and it is also possible to suppress the attachment of the silicon pieces Wb, the oxide, and the like to the surface of the silicon wafer W.

[0081] Thus, it is possible to suppress the occurrence of damage and defects on the end surface of the silicon wafer W (or the bonded wafer), and it is possible to suppress the occurrence of defects such as holes. In addition, it is possible to suppress the occurrence of bonding defects in which the silicon pieces are caught at the wafer interface at the time of bonding of the wafers.

[0082] Thus, according to the wafer support boat 1 of the present embodiment, it is possible to suppress the occurrence of the above-described various defects.

[0083] FIG. 6A is a schematic plan view of a modification example of the wafer support boat of the present embodiment in which one wafer is placed. FIG. 6B is a schematic side view of a modification example of the wafer support boat of the present embodiment.

[0084] FIG. 3A 、 FIG. 3B In the example shown in FIG. 32, the wafer W is supported by the protrusions 32 arranged in one row, but the wafer W can be supported at a plurality of positions by protrusions arranged in a plurality of rows. For example, as shown in FIG. 33, the wafer W can be supported at two positions by protrusions arranged in two rows. FIG. 6A 、 FIG. 6B As shown in FIG. 34, the wafer W can be supported at two positions by protrusions arranged in two rows.

[0085] FIG. 7 is a view for explaining the thickness of the support portion main body. The thickness t of the support portion main body 31 is preferably 2 to 30 mm. By setting the thickness t to 2 mm or more, it is possible to maintain the strength of the support portion and form the wafer groove. On the other hand, since quartz has a larger specific heat than silicon, by setting the thickness t to 30 mm or less, it is possible to suppress the occurrence of slip defects due to a temperature difference generated between the wafer and the support portion during the heat treatment process.

[0086] FIG. 8A is a view showing surface support of the support portion main body by the bottom portion of the accommodation portion. FIG. 8B is a view showing point support of the support portion main body by the bottom portion of the accommodation portion. The bottom portion 21 of the accommodation portion 2 is preferably configured to support the support portion main body 31 by surface support or point support based on a plurality of positions.

[0087] FIG. 8A In FIG. 39, the upper surface of the bottom portion 21 of the accommodation portion 2 and the lower surface of the support portion main body 31 are in surface contact, and thus the support portion main body 31 is surface supported by the bottom portion 21 of the accommodation portion 2. If surface support is performed in this way, it is possible to stably support the wafer.

[0088] FIG. 8BIn the present embodiment, a plurality of convex portions 211 are provided at equal intervals in the horizontal direction (the lateral direction in the drawing) on the upper surface of the bottom portion 21 of the housing portion 2, and the plurality of convex portions 211 are of the same height. The support portion main body 31 is placed on the plurality of convex portions 211. Thus, the support portion main body 31 is supported at a point by the bottom portion 21 of the housing portion 2. If supported at a point in this way, heat conduction from the bottom portion 21 of the housing portion 2 to the support portion main body 31 is reduced, and sharp temperature changes from the housing portion 2 to the support portion 3 are suppressed, and the occurrence of slip pits due to temperature differences between the silicon wafer W and the support portion 3 can be suppressed.

[0089] In addition, in the case of a silicon wafer, quartz is used for the support portion, and if the purity is high, the above-mentioned effects can be effectively obtained, and therefore it is more preferable to use quartz glass.

[0090] On the other hand, in the case of a wafer other than a silicon wafer, a different material can be used. For example, in the case of an alumina wafer, alumina (AI2O3) can be used as the support portion.

[0091] (Horizontal heat treatment furnace)

[0092] Next, a horizontal heat treatment furnace according to an embodiment of the present application will be described. FIG. 9 is a cross-sectional view of a horizontal heat treatment furnace according to an embodiment of the present application.

[0093] As FIG. 9 shown, the horizontal heat treatment furnace 100 has a furnace core pipe 102 extending horizontally inside a furnace main body 101. The furnace core pipe 102 has an opening portion 103 and a door 104 that opens and closes the opening portion 103 at one end, and a gas introduction pipe 105 at the other end.

[0094] In addition, the horizontal heat treatment furnace 100 has a wafer support boat 1 that is placed in the furnace core pipe 102. FIG. 9 is a cross-sectional view of a wafer support boat according to an embodiment of the present application.

[0095] In addition, in the case of heat treating a silicon wafer W, the silicon wafer W is placed in the wafer support boat 1, inserted from the opening portion 103 of the furnace core pipe 102, and disposed in the center. After the door 104 is closed to substantially seal the inside, high-purity gas such as nitrogen, oxygen, or argon is caused to flow from the gas introduction pipe 105, and the high-purity gas is discharged to the outside from the gap between the opening portion 103 and the door 104.

[0096] As an example, the horizontal heat treatment furnace 100 can be used for an oxide burying heat treatment process and a post-bonding heat treatment process in the manufacture of a silicon-on-insulator wafer, but is not limited to these heat treatments.

[0097] According to the horizontal heat treatment furnace 100 of this embodiment, the wafer support boat 1 of the above embodiment is used, so for the same reasons as those explained in the embodiment of the wafer support boat 1, the occurrence of the above-mentioned defects can be suppressed.

[0098] (Wafer heat treatment methods)

[0099] A wafer heat treatment method according to one embodiment of the present invention includes a heat treatment step of performing heat treatment using the wafer support boat of the above embodiment.

[0100] Examples of such heat treatment processes include, for example, the buried oxide heat treatment process and the post-lamination heat treatment process in the manufacturing of silicon wafers bonded to insulators, but are not limited to them.

[0101] According to the wafer heat treatment method of this embodiment, the wafer support boat of the above embodiment is used, so for the same reasons as those explained in the embodiment of the wafer support boat, the occurrence of the above-mentioned defects can be suppressed.

[0102] (Methods for manufacturing laminated wafers)

[0103] FIGS. 10A-10H This diagram illustrates the steps of a method for manufacturing a laminated wafer according to an embodiment of the present invention.

[0104] As shown in Figure 10, firstly, prepare the wafer for the active layer and the wafer for the support substrate. FIG. 10A ).

[0105] Next, a buried oxide thermal treatment process is performed to form an oxide film on the wafer of the active layer. FIG. 10B The buried oxide heat treatment process is an oxidation heat treatment process performed on the active layer wafer before bonding the active layer wafer and the support substrate wafer to form a buried oxide layer on the active layer wafer. Specifically, the silicon wafer is placed on a wafer support boat, and the wafer support boat is placed into a heat treatment furnace for heat treatment in an oxidizing atmosphere to form an oxide film on the silicon wafer. The oxide film is represented by a slash (and so on).

[0106] Next, the wafer for forming the active layer with buried oxide and the wafer for the support substrate are bonded together. FIG. 10C The active layer wafer and the support substrate wafer are aligned at the groove and bonded in a manner that prevents air, foreign matter, etc. from entering the bonding interface between the active layer wafer and the support substrate wafer.

[0107] Next, in order to improve the bonding strength, post-bonding heat treatment is performed. FIG. 10D). The post-bonding heat treatment is an oxidation heat treatment process for making the bonding of the active layer wafer and the support substrate wafer firm, which is performed after the active layer wafer and the support substrate wafer are bonded. This heat treatment stands the wafer W on which the active layer wafer and the support substrate wafer are bonded in the wafer slot of the wafer support boat, and, together with the wafer support boat, is put into a heat treatment furnace, and heat treatment is performed in an oxidation atmosphere. Thereafter, the wafer support boat is taken out of the heat treatment furnace, and thereafter, the wafer W is taken out of the wafer support boat.

[0108] Thereafter, with respect to the active layer wafer, chamfering FIG. 10E ), etching FIG. 10F ), grinding FIG. 10G ), and polishing processing FIG. 10H ) are performed, and the thickness of the active layer wafer is processed to a predetermined thickness, and a bonded silicon-on-insulator wafer is manufactured.

[0109] Here, the manufacturing method of the bonded wafer of an embodiment of the present application includes a heat treatment process of performing heat treatment using the wafer support boat of the above-described embodiment. This heat treatment process is at least one of a buried oxide heat treatment process at the time of forming a buried oxide with respect to the active layer wafer, and a post-bonding heat treatment process with respect to the bonded wafer.

[0110] According to the manufacturing method of the bonded wafer of the present embodiment, using the wafer support boat of the above-described embodiment, for the same reasons as those described in the embodiment of the wafer support boat, it is possible to suppress the occurrence of the above-described various undercuts.

[0111] Hereinafter, an embodiment of the present application will be described, but the present application is by no means limited to the following embodiment. Embodiment

[0112] As an inventive example, as shown in FIGS. 3A-3C , a wafer support boat was manufactured in which the accommodation portion was made of silicon carbide and the support portion was made of quartz glass. As a comparative example, a wafer support boat was prepared in which the entire body was made of silicon carbide.

[0113] A plurality of silicon wafers were placed in the plurality of wafer slots of these wafer support boats, and a buried oxide heat treatment process was performed at a heat treatment temperature of 1150°C for a heat treatment time of 10 hours with an oxidation film thickness of 2.5 μm, and quality evaluation was performed.

[0114] FIG. 11A is a graph showing the results of quality evaluation of the wafer end surface of the comparative example. FIG. 11B is a graph showing the results of quality evaluation of the wafer end surface of the inventive example. In the comparative example, damage and defects were observed on the wafer end surface. On the other hand, in the inventive example, no damage or defects were observed.

[0115] FIG. 12Ais a graph showing the result of luminescence point observation of the wafer surface of the comparative example. FIG. 12B is a graph showing the result of luminescence point observation of the wafer surface of the inventive example. In the comparative example, luminescence points were confirmed at the edge when the wafer support portion was confirmed. On the other hand, in the inventive example, no luminescence points were confirmed at the edge near the wafer support portion.

[0116] Explanation of Reference Signs

[0117] 1: wafer support boat,

[0118] 2: housing portion,

[0119] 21: bottom portion,

[0120] 22: side portion,

[0121] 23: upper portion,

[0122] 231: wafer slot,

[0123] 3: support portion,

[0124] 31: support portion main body,

[0125] 32: protruding portion,

[0126] 33: wafer slot,

[0127] 100: horizontal heat treatment furnace,

[0128] W: wafer.

Claims

1. A wafer supporting boat for a horizontal heat treatment furnace, characterized by comprising: a housing portion which houses a wafer and has a bottom portion, a side portion which is connected to the bottom portion and extends upward in a vertical direction, and an upper portion which is connected to the side portion and extends in a horizontal direction; and a supporting portion which is disposed at the bottom portion of the housing portion and supports a wafer, wherein the supporting portion has a supporting portion main body which extends in a direction in which wafers are arranged, and a plurality of protruding portions which protrude upward from the supporting portion main body and are arranged in a direction in which the supporting portion main body extends, and a wafer groove in which a wafer is disposed is formed between adjacent two of the protruding portions, wherein the housing portion is entirely made of silicon carbide, and wherein the supporting portion main body and the protruding portions of the supporting portion are made of quartz.

2. The wafer supporting boat according to claim 1, characterized in that a thickness of the supporting portion main body is 2 to 30 mm.

3. The wafer supporting boat according to claim 1 or 2, characterized in that the bottom portion of the housing portion is configured to support the supporting portion main body by surface support.

4. The wafer supporting boat according to claim 1 or 2, characterized in that the bottom portion of the housing portion is configured to support the supporting portion main body by point support based on a plurality of sites.

5. The wafer supporting boat according to claim 1, characterized in that the supporting portion is detachably attached to the housing portion.

6. A horizontal heat treatment furnace, characterized by comprising the wafer supporting boat according to claim 1.

7. A heat treatment method of a wafer, characterized by comprising a heat treatment step of performing heat treatment using the wafer supporting boat according to claim 1.

8. A method of manufacturing a bonded wafer, characterized by comprising a heat treatment step based on the heat treatment method of a wafer according to claim 7.

9. The method of manufacturing a bonded wafer according to claim 8, characterized in that at least one of a buried oxide heat treatment step and a post-bonding heat treatment step is performed as the heat treatment step. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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