WO2023189056A1 - Furnace core tube, heat treatment apparatus and support unit - Google Patents

Abstract

The furnace core tube includes: a tube main body having an inner wall that partitions a processing space in which a silicon carbide wafer is accommodated, the tube main body having a heat resistant temperature equal to or higher than the heat resistant temperature of the silicon carbide wafer; and a tantalum coating layer that covers the inner wall.

Description

Furnace tube, heat treatment equipment and support unit

This application claims priority based on Japanese Patent Application No. 2022-061170 filed on March 31, 2022, and the entire contents of this application are incorporated herein by reference. The present invention relates to a furnace core tube, a heat treatment device, and a support unit.

Patent Document 1 discloses a vertical heat treatment apparatus that includes a reaction tube, a heat treatment boat that supports wafers, and a heater.

US Patent Application Publication No. 2007/0148607

One embodiment provides a furnace tube, a heat treatment device, and a support unit that can contribute to high-quality heat treatment of silicon carbide wafers.

One embodiment includes: a tube body having an inner wall that partitions a processing space in which a silicon carbide wafer is accommodated and having a heat-resistant temperature higher than the heat-resistant temperature of the silicon carbide wafer; and a tantalum coating layer that covers the inner wall. A furnace core tube including:

One embodiment includes the furnace core tube, a support unit configured to be accommodated in the processing space while supporting the silicon carbide wafer, and a heating unit disposed around the furnace core tube. Provided is a heat treatment apparatus including:

One embodiment includes a column main body having a heat resistance temperature higher than a heat resistance temperature of a silicon carbide wafer and having a support portion that supports the silicon carbide wafer, and a column body having a tantalum coating layer covering the pillar body. , providing a support unit.

One embodiment is a dummy wafer used together with a silicon carbide wafer during heat treatment of the silicon carbide wafer, the dummy wafer having a wafer body having a heat resistance temperature higher than the heat resistance temperature of the silicon carbide wafer, and a tantalum coating layer covering the wafer body. We provide dummy wafers including and.

The above-mentioned and further objects, features and effects will be made clear by the embodiments described with reference to the accompanying drawings.

FIG. 1 is a schematic cross-sectional view showing a heat treatment apparatus according to a first embodiment. FIG. 2 is a schematic cross-sectional view showing the main parts of the heat treatment apparatus. FIG. 3 is a schematic cross-sectional view showing the main parts of the heat treatment apparatus. FIG. 4A is a diagram illustrating an example of a first tantalum coating layer. FIG. 4B is a diagram illustrating one embodiment of the first tantalum coating layer. FIG. 5A is a diagram illustrating one embodiment of the second tantalum coating layer. FIG. 5B is a diagram illustrating one embodiment of the second tantalum coating layer. FIG. 6A is a diagram illustrating one embodiment of the third tantalum coating layer. FIG. 6B is a diagram illustrating one embodiment of the third tantalum coating layer. FIG. 7 is a diagram for explaining an operation of the heat treatment apparatus. FIG. 8 is a schematic cross-sectional view showing a heat treatment apparatus according to the second embodiment. FIG. 9 is a diagram for explaining another example of heat treatment of a SiC wafer. FIG. 10 is a diagram for explaining an example of a form of a dummy wafer. FIG. 11A is a diagram illustrating an example of a fourth tantalum coating layer. FIG. 11B is a diagram illustrating one embodiment of the fourth tantalum coating layer.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. The attached drawings are schematic diagrams and are not strictly illustrated, and the scale etc. do not necessarily match. Further, corresponding structures in the accompanying drawings are denoted by the same reference numerals, and overlapping explanations are omitted or simplified. For structures whose explanations have been omitted or simplified, the explanation given before the abbreviation or simplification applies. In the embodiment, words such as "first", "second", "third", etc. are used, but these are symbols attached to the name of each structure to clarify the order of explanation; It is not given for the purpose of limiting the name.

FIG. 1 is a schematic cross-sectional view showing a heat treatment apparatus 1A according to the first embodiment. FIG. 2 is a schematic cross-sectional view showing the main parts of the heat treatment apparatus 1A. FIG. 3 is a schematic cross-sectional view showing the main parts of the heat treatment apparatus 1A.

Referring to FIGS. 1 to 3, the heat treatment apparatus 1A, in this embodiment, consists of a vertical heat treatment furnace used for heat treatment of SiC wafers 2 (silicon carbide wafers). The heat treatment includes thermal oxidation treatment for the SiC wafer 2, annealing treatment for the SiC wafer 2, activation treatment for impurities (trivalent elements, pentavalent elements, etc.) for the SiC wafer 2, and CVD treatment for the SiC wafer 2 (e.g., low pressure CVD treatment). , including Si vapor pressure etching treatment on the SiC wafer 2, etc.

The SiC wafer 2 is a base member of a SiC semiconductor device. After a predetermined device structure is formed on the SiC wafer 2, a plurality of SiC semiconductor devices are manufactured by cutting the SiC wafer 2 in a predetermined pattern. The SiC wafer 2 includes a hexagonal SiC single crystal and is formed into a plate shape (disk shape). The hexagonal SiC single crystal has multiple types of polytypes including 2H (Hexagonal)-SiC single crystal, 4H-SiC single crystal, 6H-SiC single crystal, and the like. In this embodiment, an example is shown in which the SiC wafer 2 includes a 4H-SiC single crystal, but the SiC wafer 2 may include other polytypes.

The SiC wafer 2 has a first main surface 3 on one side, a second main surface 4 on the other side, and a side surface 5 connecting the first main surface 3 and the second main surface 4. The first main surface 3 and the second main surface 4 are preferably formed of a c-plane of a SiC single crystal. Preferably, the first main surface 3 is formed by a silicon surface of a SiC single crystal, and the second main surface 4 is formed by a carbon surface of a SiC single crystal.

The first main surface 3 and the second main surface 4 may have an off angle that is inclined at a predetermined angle in a predetermined off direction with respect to the c-plane. The off direction is preferably the a-axis direction ([11-20] direction) of the SiC single crystal. The off angle may be greater than 0° and less than or equal to 10°. The off angle is preferably 5° or less.

The SiC wafer 2 may have a mark indicating the crystal direction of the SiC single crystal on the side surface 5. The mark may be an orientation flat consisting of a notch extending linearly or an orientation notch consisting of a notch concave in a polygonal shape (for example, triangular) toward the center.

The SiC wafer 2 may have an outer diameter (diameter) of 50 mm or more and 300 mm or less (that is, 2 inches or more and 12 inches or less) in plan view. The outer diameter of the SiC wafer 2 is defined by the length of a chord passing through the center of the SiC wafer 2. SiC wafer 2 may have a thickness of 100 μm or more and 1100 μm or less.

Although specific illustration is omitted, the SiC wafer 2 may have a stacked structure including a SiC substrate and an SiC epitaxial layer stacked on the SiC substrate. In this case, the second main surface 4 is formed by the SiC substrate, and the first main surface 3 is formed by the SiC epitaxial layer. The SiC substrate may have an n-type impurity concentration. The SiC epitaxial layer may have a different n-type impurity concentration than the SiC substrate.

The n-type impurity concentration of the SiC epitaxial layer may be lower than the n-type impurity concentration of the SiC substrate. Preferably, the SiC epitaxial layer has a thickness less than the thickness of the SiC substrate. The thickness of the SiC epitaxial layer may be 1 μm or more and 50 μm or less. The thickness of the SiC epitaxial layer is preferably 5 μm or more and 25 μm or less.

The SiC substrate may have a p-type impurity concentration. The SiC epitaxial layer may have a different p-type impurity concentration than the SiC substrate. While the SiC substrate has an n-type impurity concentration, the SiC epitaxial layer may have a p-type impurity concentration. While the SiC substrate has a p-type impurity concentration, the SiC epitaxial layer may have an n-type impurity concentration.

The heat treatment apparatus 1A includes a furnace core tube 10. The furnace core tube 10 includes a tube body 11 and a first tantalum coating layer 12 . The first tantalum coating layer 12 may be referred to as a "core side tantalum coating layer."

The tube body 11 has a cylindrical single-tube structure having a closed end on one side (upper side in the vertical direction) and an open end on the other side (lower side in the vertical direction). The tube body 11 has an inner wall 14 that defines a processing space 13 in which at least one SiC wafer 2 is accommodated, and is arranged with the open end facing downward in the vertical direction. Processing space 13 may also be referred to as an "internal space" or "accommodation space."

Specifically, the tube body 11 is divided into a cylindrical (for example, cylindrical) tubular wall 15, a top wall 16 (closed end) that closes one end of the tubular wall 15, and the other end of the tubular wall 15. It has a furnace mouth part 17 (open end). The inner wall 14 of the tube body 11 is defined by an inner wall portion of the tubular wall 15 and an inner wall portion of the top wall 16 .

In this embodiment, the tube body 11 is formed into a longitudinal cylindrical shape extending in one direction (specifically, a longitudinal cylindrical shape extending in the vertical direction), and has a processing space 13 in which a plurality of SiC wafers 2 are accommodated. There is. The tube body 11 is made of a material having a heat resistant temperature higher than the heat resistant temperature of the SiC wafer 2 . The allowable temperature limit of the SiC wafer 2 may be defined by the sublimation temperature (2300° C. to 2600° C.) of the SiC wafer 2.

The allowable temperature limit of the tube body 11 may be defined by the lower of the melting temperature of the tube body 11 and the sublimation temperature of the tube body 11. The tube body 11 preferably has a heat-resistant temperature of 2300° C. or higher. It is particularly preferable that the tube body 11 has a heat-resistant temperature of 2600° C. or higher.

The tube body 11 may include at least one of an inorganic material having a metal element, an inorganic material having a non-metal element, and an inorganic material having a metal element and a non-metal element. The tube body 11 may include at least one of a nonmetal, a nonalloy, an alloy, and a ceramic. Preferably, the tube body 11 contains at least one of carbon (C), molybdenum (Mo), tantalum (Ta), tungsten (W), and silicon carbide (SiC).

The first tantalum coating layer 12 only needs to cover at least a portion of the inner wall 14. The first tantalum coating layer 12 may cover either the inner wall portion of the tubular wall 15 or the inner wall portion of the top wall 16. Preferably, the first tantalum coating layer 12 covers both the inner wall portion of the tubular wall 15 and the inner wall portion of the top wall 16. It is particularly preferred that the first tantalum coating layer 12 covers the entire inner wall 14 .

The first tantalum coating layer 12 may cover a part of the outer wall of the tube body 11. That is, the first tantalum coating layer 12 may cover either or both of the outer wall portion of the tubular wall 15 and the outer wall portion of the top wall 16. The first tantalum coating layer 12 may cover the entire outer wall of the tube body 11.

For example, the first tantalum coating layer 12 may have the configuration shown in FIGS. 4A and 4B. 4A and 4B are diagrams illustrating an example of a form of the first tantalum coating layer 12. Referring to FIG. 4A, the first tantalum coating layer 12 has a laminated structure including a first tantalum layer 18, a first tantalum carbide layer 19, and a first tantalum silicide layer 20 laminated in this order from the tube body 11 side. You may do so. Such a structure is preferably applied when the wall surface (inner wall 14) of the tube body 11 is made of a material other than tantalum.

The first tantalum layer 18 includes a pure Ta layer (a Ta layer with a purity of 99% or more). The first tantalum carbide layer 19 may have a single layer structure or a laminated structure including at least one of the Ta ₂ C layer 19a and the TaC layer 19b. In this embodiment, the first tantalum carbide layer 19 has a laminated structure including a Ta ₂ C layer 19a and a TaC layer 19b laminated in this order from the tube body 11 side.

The first tantalum silicide layer 20 includes a Ta _α Si _β C _γ layer. The first tantalum silicide layer 20 has a single-layer structure or a laminated structure including at least one of two TaSi layers, three Ta _{5 Si} layers, a Ta ₂ Si layer, a Ta ₃ Si layer, and a Ta ₅ Si ₃ C _0.5 layer _. It may have a structure.

It is preferable that the first tantalum silicide layer 20 has a single layer structure or a laminated structure including one or both of _two TaSi layers and _three Ta ₅ Si layers. The first tantalum silicide layer 20 preferably has a thickness less than the thickness of the first tantalum carbide layer 19 . Of course, the first tantalum silicide layer 20 may have a thickness greater than the thickness of the first tantalum carbide layer 19.

Referring to FIG. 4B, the first tantalum coating layer 12 may have a laminated structure including a first tantalum carbide layer 19 and a first tantalum silicide layer 20 laminated in this order from the tube body 11 side. Such a structure is preferably applied when the wall surface (inner wall 14) of the tube body 11 is made of tantalum.

The heat treatment apparatus 1A includes a lid unit 25 configured to open and close the furnace mouth portion 17 on one end side of the furnace tube 10. For example, the lid unit 25 includes a lid made of metal (for example, stainless steel). Of course, the lid body may be made of the same material as the tube body 11. The lid unit 25 increases the airtightness within the processing space 13 by closing the furnace mouth portion 17 .

The heat treatment apparatus 1A includes a heat retention unit 26 configured to restrict the movement of heat in and out of the processing space 13 via the furnace opening 17. For example, the heat retention unit 26 includes a heat retention cylinder as an example of a heat insulating material. The heat retention unit 26 is disposed above the lid unit 25 so that it is accommodated in the processing space 13 with the reactor core tube 10 closed by the lid unit 25.

The heat treatment apparatus 1A includes a support unit 30 configured to be accommodated in the processing space 13 while supporting at least one SiC wafer 2. Support unit 30 may be referred to as a "wafer boat." The support unit 30 is placed above the lid unit 25 with the heat retention unit 26 in between so that the furnace core tube 10 is accommodated in the processing space 13 with the lid unit 25 closed. In this embodiment, the support unit 30 is configured to support a plurality of SiC wafers 2.

Specifically, the support unit 30 includes a first support plate 31 on one side (closed end side of the furnace core tube 10), a second support plate 32 on the other side (open end side of the furnace core tube 10), and a first support plate 31 on one side (closed end side of the furnace core tube 10). It includes at least one (in this embodiment, a plurality of) columns 33 connected to the support plate 31 and the second support plate 32 . The second support plate 32 is fixed to the heat retention unit 26. Support unit 30 includes three columns 33 in this form.

The first support plate 31 and the second support plate 32 each include a plate main body 34 and a second tantalum coating layer 35. The second tantalum coating layer 35 may be referred to as a "support side tantalum coating layer." The plate main body 34 is formed into a plate shape (for example, a disk shape or an annular plate shape). The plate main body 34 has an outer diameter (diameter) larger than the outer diameter of the SiC wafer 2 in plan view. Preferably, the plate main body 34 has a thickness that exceeds the thickness of the SiC wafer 2.

The plate main body 34 is formed of a material having a heat resistant temperature higher than the heat resistant temperature of the SiC wafer 2. The allowable temperature limit of the plate body 34 may be defined by the lower of the melting temperature of the plate body 34 and the sublimation temperature of the plate body 34. The heat resistant temperature of the plate main body 34 is preferably 2300° C. or higher. It is particularly preferable that the heat resistant temperature of the plate main body 34 is 2600° C. or higher.

The plate main body 34 may include at least one of an inorganic material having a metal element, an inorganic material having a non-metal element, and an inorganic material having a metal element and a non-metal element. The plate body 34 may include at least one of a nonmetal, a nonalloy, an alloy, and a ceramic. Preferably, the plate main body 34 contains at least one of carbon (C), molybdenum (Mo), tantalum (Ta), tungsten (W), and silicon carbide (SiC).

The second tantalum coating layer 35 only needs to cover at least a portion of the outer surface of the plate body 34. The second tantalum coating layer 35 preferably covers a portion of the outer surface of the plate body 34 that is exposed to the processing space 13 . It is particularly preferable that the second tantalum coating layer 35 covers the entire area of the plate body 34.

For example, the second tantalum coating layer 35 may have the configuration shown in FIGS. 5A and 5B. 5A and 5B are diagrams showing an example of a form of the second tantalum coating layer 35. Referring to FIG. 5A, the second tantalum coating layer 35 has a laminated structure including a second tantalum layer 36, a second tantalum carbide layer 37, and a second tantalum silicide layer 38 laminated in this order from the plate main body 34 side. You may do so. Such a structure is preferably applied when the wall surface of the plate main body 34 is made of a material other than tantalum.

The second tantalum layer 36 includes a pure Ta layer (a Ta layer with a purity of 99% or more). The second tantalum carbide layer 37 may have a single layer structure or a laminated structure including at least one of the Ta ₂ C layer 36a and the TaC layer 36b. In this embodiment, the second tantalum carbide layer 37 has a laminated structure including a Ta ₂ C layer 36a and a TaC layer 36b laminated in this order from the plate main body 34 side.

The second tantalum silicide layer 38 includes a Ta _α Si _β C _γ layer. The second tantalum silicide layer 38 has a single-layer structure or a laminated structure including at least one of two TaSi layers, three Ta _{5 Si} layers, a Ta ₂ Si layer, a Ta ₃ Si layer, and a Ta ₅ Si ₃ C _0.5 layer _. It may have a structure.

The second tantalum silicide layer 38 preferably has a single-layer structure or a laminated structure including one or both of _two TaSi layers and _three Ta ₅ Si layers. The second tantalum silicide layer 38 preferably has a thickness less than the thickness of the second tantalum carbide layer 37. Of course, the second tantalum silicide layer 38 may have a thickness greater than the thickness of the second tantalum carbide layer 37.

Referring to FIG. 5B, the second tantalum coating layer 35 may have a laminated structure including a second tantalum carbide layer 37 and a second tantalum silicide layer 38 laminated in this order from the plate main body 34 side. Such a structure is preferably applied when the wall surface of the plate main body 34 is made of tantalum.

The plurality of support columns 33 are arranged at equal intervals along the circumferential direction of the first support plate 31 and the second support plate 32. Each support 33 is formed into a columnar shape (cylindrical or prismatic) extending in the vertical direction, and has a first end 33a on one side (first support plate 31 side) and a first end 33a on the other side (second support plate 32 side). It has two end portions 33b. The first end 33a is fixed to the first support plate 31, and the second end 33b is fixed to the second support plate 32. The method of fixing the first end 33a to the first support plate 31 and the method of fixing the second end 33b to the second support plate 32 are arbitrary.

The first end 33a may be inserted into a groove or hole provided in the first support plate 31. Of course, the first end 33a may be welded or bolted to the first support plate 31. The second end portion 33b may be inserted into a groove or hole provided in the second support plate 32. Of course, the second end portion 33b may be welded or bolted to the second support plate 32.

The plurality of pillars 33 each include a pillar body 39 and a third tantalum coating layer 40. The third tantalum coating layer 40 may be referred to as a "post-side tantalum coating layer." The column main body 39 is formed in a columnar shape (cylindrical or prismatic) extending in the vertical direction, and has a first end 33a and a second end 33b.

The pillar body 39 includes a plurality of support parts 41 formed at intervals in the vertical direction (longitudinal direction) in the region between the first end 33a and the second end 33b. In this embodiment, each of the plurality of support parts 41 is formed by a slit 42 formed in a cutout shape (groove shape). The slit 42 may also be referred to as a "support groove."

Between the plurality of pillar bodies 39, the plurality of slits 42 are provided at the same height along the vertical direction, and are each configured to abut against the peripheral edge of the SiC wafer 2. It is preferable that the plurality of slits 42 (support portions 41) are formed at equal intervals in the vertical direction.

The plurality of pillar bodies 39 support the plurality of SiC wafers 2 in a horizontal position in multiple stages at intervals in the vertical direction through the plurality of slits 42 . The plurality of slits 42 may be in contact with the peripheral edge of the first main surface 3 of the SiC wafer 2 or may be in contact with the peripheral edge of the second main surface 4 of the SiC wafer 2.

The pillar body 39 is formed of a material having a heat resistant temperature higher than the heat resistant temperature of the SiC wafer 2. The allowable temperature limit of the column body 39 may be defined by the lower of the melting temperature of the column body 39 and the sublimation temperature of the column body 39. The heat resistant temperature of the column main body 39 is preferably 2300° C. or higher. It is particularly preferable that the heat resistant temperature of the column main body 39 is 2600° C. or higher.

The pillar body 39 may include at least one of an inorganic material having a metal element, an inorganic material having a non-metal element, and an inorganic material having a metal element and a non-metal element. The pillar body 39 may include at least one of a nonmetal, a nonalloy, an alloy, and a ceramic. The pillar body 39 preferably contains at least one of carbon (C), molybdenum (Mo), tantalum (Ta), tungsten (W), and silicon carbide (SiC).

The third tantalum coating layer 40 only needs to cover at least a portion of the outer surface of the pillar body 39. The third tantalum coating layer 40 preferably covers a portion of the outer surface of the column body 39 that is exposed to the processing space 13 . It is preferable that the third tantalum coating layer 40 covers the plurality of slits 42 of the pillar body 39.

The third tantalum coating layer 40 is preferably formed in the form of a film along the wall surfaces of the plurality of slits 42 so as to partition the plurality of slits 42. In this case, the third tantalum coating layer 40 is brought into contact with the peripheral edge of the SiC wafer 2 within the slit 42 . It is particularly preferable that the third tantalum coating layer 40 covers the entire area of the column body 39.

For example, the third tantalum coating layer 40 may have the configuration shown in FIGS. 6A and 6B. FIGS. 6A and 6B are diagrams showing an example of a form of the third tantalum coating layer 40. Referring to FIG. 6A, the third tantalum coating layer 40 has a laminated structure including a third tantalum layer 43, a third tantalum carbide layer 44, and a third tantalum silicide layer 45 laminated in this order from the pillar body 39 side. You may do so. Such a structure is preferably applied when the wall surface of the column main body 39 is made of a material other than tantalum.

The third tantalum layer 43 includes a pure Ta layer (a Ta layer with a purity of 99% or more). The third tantalum carbide layer 44 may have a single layer structure or a laminated structure including at least one of the Ta ₂ C layer 44a and the TaC layer 44b. In this embodiment, the third tantalum carbide layer 44 has a laminated structure including a Ta ₂ C layer 44a and a TaC layer 44b laminated in this order from the column main body 39 side.

The third tantalum silicide layer 45 includes a Ta _α Si _β C _γ layer. The third tantalum silicide layer 45 has a single-layer structure or a laminated structure including at least _one of two TaSi layers, three Ta _{5 Si} layers, a Ta ₂ Si layer, a Ta ₃ Si layer, and a Ta ₅ Si ₃ C _0.5 layer. It may have a structure.

It is preferable that the third tantalum silicide layer 45 has a single layer structure or a laminated structure including one or both of _two TaSi layers and _three Ta ₅ Si layers. The third tantalum silicide layer 45 preferably has a thickness less than the thickness of the third tantalum carbide layer 44 . Of course, the third tantalum silicide layer 45 may have a thickness greater than the thickness of the third tantalum carbide layer 44.

Referring to FIG. 6B, the third tantalum coating layer 40 may have a laminated structure including a third tantalum carbide layer 44 and a third tantalum silicide layer 45 laminated in this order from the pillar body 39 side. Such a structure is preferably applied when the wall surface of the column main body 39 is made of tantalum.

The heat treatment apparatus 1A includes a transport unit 50 that transports the support unit 30 into the processing space 13 and transports the support unit 30 from the processing space 13. In this embodiment, the transport unit 50 includes a lifting unit attached to a portion of the lid unit 25 located on the opposite side of the furnace core tube 10, and lifts and lowers the lid unit 25 to one side and the other side in the vertical direction.

Specifically, the transport unit 50 integrally moves the lid unit 25, the heat retention unit 26, and the support unit 30 up and down between the processing position and the retreat position. The processing position is a position where the reactor core tube 10 is closed by the lid unit 25 and the support unit 30 and the heat retention unit 26 are housed within the reactor core tube 10 . The retracted position is a position where the support unit 30 and the heat retention unit 26 are exposed from the core tube 10 and the support unit 30 and the heat retention unit 26 can be removed.

The heat treatment apparatus 1A includes a gas supply unit 51 that supplies processing gas into the furnace core tube 10, and a gas exhaust unit 52 that exhausts the processing gas inside the furnace core tube 10. The gas supply unit 51 is attached to the top wall 16 of the furnace core tube 10 in this embodiment. The gas exhaust unit 52 is in this embodiment attached to the tubular wall 15 of the reactor core tube 10 . Of course, the gas supply unit 51 may be attached to the tubular wall 15 and the gas exhaust unit 52 may be attached to the top wall 16.

The processing gas supplied into the furnace core tube 10 differs depending on the content of the heat treatment. There may be one type of processing gas, or there may be multiple types of processing gas. For example, when impurity activation processing is performed on the SiC wafer 2, the processing gas may be a gas containing Si (for example, silane gas (SiH ₄ )). For example, when a thermal oxidation process is performed on the SiC wafer 2, the process gas may be oxygen gas. Of course, the processing gas may contain an inert gas. Further, a plurality of gas supply units 51 may be connected to the furnace core tube 10 depending on the type of gas to be supplied.

The heat treatment apparatus 1A includes a heating unit 53 arranged around the furnace tube 10 so as to heat the SiC wafer 2 in the processing space 13 from outside the furnace tube 10. The heating unit 53 may include a cylindrical heater surrounding the furnace core tube 10.

The heat treatment apparatus 1A includes a control unit 54 that is connected to a transport unit 50, a gas supply unit 51, a gas exhaust unit 52, and a heating unit 53, and controls the transport unit 50, gas supply unit 51, gas exhaust unit 52, and heating unit 53. include. For example, the control unit 54 includes a CPU and memory (for example, ROM, RAM, non-volatile memory, etc.), and controls the transport unit 50, the gas supply unit 51, the gas exhaust unit 52, and the like based on a predetermined processing recipe stored in the memory. Controls heating unit 53.

In the heat treatment process for the SiC wafer 2 using the heat treatment apparatus 1A (that is, the method for manufacturing a SiC semiconductor device), first, the support unit 30 that supports at least one SiC wafer 2 is placed in a retracted position with the heat insulating unit 26 in between. mounted on the unit 25 (first step).

Next, the support unit 30 is raised from the retracted position to the processing position by the transport unit 50, and the support unit 30 is housed in the reactor core tube 10 (second step). Next, a predetermined processing gas is supplied into the processing space 13, and the SiC wafer 2 is heated by the heating unit 53 (third step). For example, the SiC wafer 2 is heated in a predetermined processing gas atmosphere in a temperature range of 1500° C. or more and 2200° C. or less (preferably a temperature range of 1600° C. or more and 2000° C. or less).

The heat treatment for the SiC wafer 2 includes thermal oxidation treatment for the SiC wafer 2, annealing treatment for the SiC wafer 2, activation treatment for impurities (trivalent elements, pentavalent elements, etc.) for the SiC wafer 2, and CVD treatment for the SiC wafer 2 (for example, (low pressure CVD treatment), Si vapor pressure etching treatment for the SiC wafer 2, or the like. When the heat treatment process for the SiC wafer 2 is completed, the support unit 30 is lowered from the processing position to the retreat position by the transport unit 50, and the support unit 30 is removed from the furnace tube 10 (third step).

FIG. 7 is a diagram for explaining an action of the heat treatment apparatus 1A. Referring to FIG. 7, when SiC wafer 2 is heated, Si atoms (silicon atoms) are separated from the SiC single crystal as vapor due to thermal decomposition. C atoms (carbon atoms) remain on the second main surface 4 and the side surface 5).

In this form, the furnace core tube 10 includes a first tantalum coating layer 12 that coats the inner wall 14 of the tube body 11. According to the first tantalum coating layer 12, the C atoms of the SiC wafer 2 can be reacted with Ta atoms through the atmosphere of the processing space 13. Thereby, C atoms can be taken into the first tantalum coating layer 12, and the C atoms remaining on the outer surface of the SiC wafer 2 are reduced. Therefore, roughness on the outer surface of the SiC wafer 2 caused by C atoms can be suppressed, so that the SiC wafer 2 can be heat-treated with high quality.

Specifically, the first tantalum coating layer 12 includes a first tantalum silicide layer 20 that covers the inner wall 14 of the tube body 11. According to this structure, the first tantalum silicide layer 20 can function as a Si supply source. That is, the first tantalum silicide layer 20 supplies Si vapor into the processing space 13 by being heated simultaneously with the SiC wafer 2 .

Si vapor generated from the first tantalum silicide layer 20 reacts with C atoms generated on the outer surface of the SiC wafer 2. As a result, C atoms are removed from the outer surface of the SiC wafer 2. In the processing space 13, vapor containing Si ₂ C, SiC ₂ , etc. is generated as a result of the reaction between Si vapor and C atoms. The steam containing Si ₂ C and SiC ₂ reacts with the first tantalum silicide layer 20 of the furnace tube 10, and as a result, TaC, Ta ₂ C, Si, TaSi _2, etc. are generated on the furnace tube 10 side.

For example, when the first tantalum silicide layer 20 includes TaSi ₂ , TaC and Si are generated as a result of Si ₂ C reacting with TaSi ₂ . For example, when the first tantalum silicide layer 20 includes Ta ₅ Si ₃ , Ta ₂ C and TaSi ₂ are generated as a result of Si ₂ C reacting with Ta ₅ Si ₃ . In this way, C atoms such as Si ₂ C and SiC ₂ in the processing space 13 are incorporated into the first tantalum silicide layer 20 . Therefore, roughness on the outer surface of the SiC wafer 2 caused by C atoms can be appropriately suppressed.

The first tantalum coating layer 12 may include a first tantalum carbide layer 19 interposed between the tube body 11 and the first tantalum silicide layer 20. According to this structure, the reaction rate in the SiC wafer 2 can be adjusted depending on the composition of the first tantalum carbide layer 19 and the first tantalum silicide layer 20.

The heat treatment apparatus 1A may include a gas supply unit 51 that supplies processing gas to the processing space 13. In this case, a gas containing Si (for example, silane gas (SiH ₄ )) may be supplied to the processing space 13 by the gas supply unit 51. According to this structure, Si vapor can be created in the processing space 13 using the gas supply unit 51.

The Si vapor originating from the gas supply unit 51 reacts with C atoms generated on the outer surface of the SiC wafer 2, and as a result, vapor containing Si ₂ C, SiC _2, etc. is generated in the processing space 13. C atoms such as Si ₂ C and SiC ₂ are incorporated into the first tantalum coating layer 12 . Therefore, by using the first tantalum coating layer 12 and the gas containing Si, roughness on the outer surface of the SiC wafer 2 caused by C atoms can be appropriately suppressed.

The support unit 30 includes a first support plate 31 , a second support plate 32 , and a column 33 connected to the first support plate 31 and the second support plate 32 . The first support plate 31 (second support plate 32) may include a second tantalum carbide layer 37 covering the plate body 34. In this case, the first support plate 31 (second support plate 32) also provides the same functions and effects as those described for the furnace core tube 10. Post 33 may include a third tantalum carbide layer 44 covering post body 39 . In this case, the struts 33 also have the same functions and effects as those described for the furnace core tube 10.

FIG. 8 is a schematic cross-sectional view showing a heat treatment apparatus 1B according to the second embodiment. In the first embodiment described above, the furnace core tube 10 having the tube body 11 having a single tube structure was shown. On the other hand, the heat treatment apparatus 1B according to the second embodiment includes a core tube 10 having a tube body 61 having a cylindrical multi-tube structure having a closed end on one side and an open end on the other side.

As in the case of the first embodiment, the tube body 61 has an inner wall 14 that defines a processing space 13 in which at least one SiC wafer 2 is accommodated, and is arranged with the open end facing downward in the vertical direction. There is.

In this form, the tube body 61 includes an inner tube 62 located inside and an outer tube 63 located outside the inner tube 62, and has an inner wall 14 constituted by the inner tube 62 and the outer tube 63. There is. The inner tube 62 has a cylindrical (for example, cylindrical) inner tubular wall 64 having a first open end on one side (upper side in the vertical direction) and a second open end on the other side (lower side in the vertical direction). ing. The inner wall portion of the inner tubular wall 64 defines a portion of the inner wall 14 .

The outer tube 63 has a cylindrical (for example, cylindrical) outer tubular wall 65 and an outer top wall 66 that closes one end of the outer tubular wall 65. The outer tube 63 is fitted onto the inner tube 62 (inner tubular wall 64) from the first open end side. The inner wall portion of the outer tubular wall 65 and the inner wall portion of the outer top wall 66 each define a portion of the inner wall 14.

In this form, the outer tube 63 (outer tubular wall 65) defines the furnace mouth portion 17 at its lower end. Of course, the shapes of the inner tube 62 (inner tubular wall 64) and the outer tube 63 (outer tubular wall 65) are changed so that the furnace opening 17 is defined at the lower end of the inner tube 62 (inner tubular wall 64). It's okay.

In this embodiment, the tube main body 61 is formed into a longitudinal cylindrical shape (specifically, a longitudinal cylindrical shape) extending in the vertical direction by an inner tube 62 and an outer tube 63, and is configured to accommodate a plurality of SiC wafers 2. has been done. The tube body 11 (inner tube 62 and outer tube 63) is formed of a material having a heat resistant temperature higher than the heat resistant temperature of the SiC wafer 2, as in the first embodiment.

The furnace core tube 10 includes the first tantalum coating layer 12 covering the tube body 61, as in the first embodiment. The first tantalum coating layer 12 only needs to cover at least the inner wall 14 of the tube body 61. The first tantalum coating layer 12 only needs to cover at least one of the inner wall of the inner tubular wall 64 , the inner wall of the outer tubular wall 65 , and the inner wall of the outer top wall 66 .

The first tantalum coating layer 12 preferably covers the entire inner wall portion of the inner tubular wall 64. Preferably, the first tantalum coating layer 12 covers the entire inner wall portion of the outer tubular wall 65. Preferably, the first tantalum coating layer 12 covers the entire inner wall portion of the outer top wall 66. It is preferable that the first tantalum coating layer 12 covers the entire inner wall 14 of the tube body 61.

The first tantalum coating layer 12 may cover part or all of the outer wall portion of the inner tubular wall 64. The first tantalum coating layer 12 may cover part or all of the outer wall portion of the outer tubular wall 65. The first tantalum coating layer 12 may cover part or all of the outer wall portion of the outer top wall 66.

In this form, the gas supply unit 51 is attached to the lower end of the furnace core tube 10 (the outer tube 63 in this form). Of course, the gas supply unit 51 may be attached to the inner tube 62 side at the lower end of the reactor core tube 10 depending on the arrangement of the inner tube 62 and the outer tube 63. In this embodiment, the gas exhaust unit 52 is formed in the outer tube 63 so that an exhaust flow path is formed in the space between the inner tube 62 and the outer tube 63. Of course, the arrangement of the gas supply unit 51 and the gas exhaust unit 52 may be interchanged.

The configurations of the lid unit 25, heat retention unit 26, support unit 30, transport unit 50, heating unit 53, and control unit 54 are the same as in the first embodiment, so their description will be omitted. As described above, the heat treatment apparatus 1B also provides the same functions and effects as those described for the heat treatment apparatus 1A.

Hereinafter, with reference to FIGS. 9 and 10, another example of heat treatment of the SiC wafer 2 (that is, one method of manufacturing a SiC semiconductor device) applied during the heat treatment process of the heat treatment apparatus 1A and the heat treatment apparatus 1B described above will be explained. Ru. FIG. 9 is a diagram for explaining another example of heat treatment of the SiC wafer 2. FIG. 10 is a diagram for explaining an example of a form of the dummy wafer 70. In FIG. 9, a heat treatment apparatus 1A is illustrated.

Referring to FIG. 9, in the heat treatment process of SiC wafer 2, at least one dummy wafer 70 and at least one SiC wafer 2 may be supported by support unit 30. In this case, it is preferable that at least one dummy wafer 70 and at least one SiC wafer 2 be supported by the support unit 30 so as to face each other.

For example, a plurality of dummy wafers 70 may be supported by the support unit 30 so as to sandwich one or more SiC wafers 2 therebetween. In FIG. 9, as an example, a plurality of dummy wafers 70 and a plurality of SiC wafers 2 are alternately supported by the support unit 30. The structure of the dummy wafer 70 will be explained below.

Referring to FIG. 10, dummy wafer 70 includes a wafer body 71 and a fourth tantalum coating layer 72. The fourth tantalum coating layer 72 may be referred to as a "wafer side tantalum coating layer." The wafer body 71 is made of a material having a heat resistant temperature higher than the heat resistant temperature of the SiC wafer 2 . The allowable temperature limit of the wafer body 71 may be defined by the lower of the melting temperature of the wafer body 71 and the sublimation temperature of the wafer body 71.

The heat-resistant temperature of the wafer body 71 is preferably 2300° C. or higher. It is particularly preferable that the heat resistant temperature of the wafer body 71 is 2600° C. or higher. The wafer body 71 may include at least one of an inorganic material having a metal element, an inorganic material having a non-metal element, and an inorganic material having a metal element and a non-metal element.

The wafer body 71 may include at least one of a nonmetal, a nonalloy, an alloy, and a ceramic. The wafer body 71 preferably contains at least one of carbon (C), molybdenum (Mo), tantalum (Ta), tungsten (W), and silicon carbide (SiC).

In view of attachment to the support unit 30, the wafer body 71 is preferably formed using the SiC wafer 2. That is, the wafer main body 71 preferably includes a hexagonal SiC single crystal and is formed in a plate shape (disk shape). In this case, the wafer body 71 may be formed of 2H (Hexagonal)-SiC single crystal, 4H-SiC single crystal, 6H-SiC single crystal, or the like. The wafer body 71 is preferably formed of 4H-SiC single crystal.

The wafer body 71 has a first wafer main surface 73 on one side, a second wafer main surface 74 on the other side, and a wafer side surface 75 connecting the first wafer main surface 73 and the second wafer main surface 74. There is. The first wafer main surface 73 and the second wafer main surface 74 are preferably formed of a c-plane of SiC single crystal. Preferably, the first wafer main surface 73 is formed by a silicon surface of a SiC single crystal, and the second wafer main surface 74 is formed by a carbon surface of a SiC single crystal.

The first wafer main surface 73 and the second wafer main surface 74 may have an off angle that is inclined at a predetermined angle in a predetermined off direction with respect to the c-plane. The off direction is preferably the a-axis direction ([11-20] direction) of the SiC single crystal. The off angle may be greater than 0° and less than or equal to 10°. The off angle is preferably 5° or less.

The wafer body 71 may have an orientation flat (a notch that extends linearly) or an orientation notch (a notch that is triangularly depressed toward the center) that indicates the crystal direction of the SiC single crystal on the wafer side surface 75. . The wafer body 71 may have an outer diameter (diameter) of 50 mm or more and 300 mm or less (that is, 2 inches or more and 12 inches or less) in plan view.

The outer diameter of the wafer body 71 is preferably approximately equal to the outer diameter of the SiC wafer 2. The wafer body 71 may have a thickness of 100 μm or more and 1100 μm or less. The thickness of the wafer body 71 may be greater than or equal to the thickness of the SiC wafer 2, or may be less than the thickness of the SiC wafer 2.

Although specific illustration is omitted, the wafer main body 71 may have a stacked structure including a SiC substrate and a SiC epitaxial layer stacked on the SiC substrate. In this case, the second wafer main surface 74 is formed by the SiC substrate, and the first wafer main surface 73 is formed by the SiC epitaxial layer. For example, the SiC substrate may have an n-type impurity concentration. The SiC epitaxial layer may have a different n-type impurity concentration than the SiC substrate.

The n-type impurity concentration of the SiC epitaxial layer may be lower than the n-type impurity concentration of the SiC substrate. Preferably, the SiC epitaxial layer has a thickness less than the thickness of the SiC substrate. The thickness of the SiC epitaxial layer may be 1 μm or more and 50 μm or less. The thickness of the SiC epitaxial layer is preferably 5 μm or more and 25 μm or less. Of course, the wafer body 71 may have a single layer structure made of a SiC substrate.

The SiC substrate may have a p-type impurity concentration. The SiC epitaxial layer may have a different p-type impurity concentration than the SiC substrate. While the SiC substrate has an n-type impurity concentration, the SiC epitaxial layer may have a p-type impurity concentration. While the SiC substrate has a p-type impurity concentration, the SiC epitaxial layer may have an n-type impurity concentration.

The fourth tantalum coating layer 72 only needs to cover a part of the wafer body 71. The fourth tantalum coating layer 72 preferably covers one or both of the first wafer main surface 73 and the second wafer main surface 74. It is particularly preferable that the fourth tantalum coating layer 72 covers the entire area of one or both of the first wafer main surface 73 and the second wafer main surface 74. The fourth tantalum coating layer 72 may cover the entire area of the wafer body 71 (first wafer main surface 73, second wafer main surface 74, and wafer side surface 75).

For example, the fourth tantalum coating layer 72 may have the configuration shown in FIGS. 11A and 11B. FIG. 11A and FIG. 11B are diagrams showing an example of a form of the fourth tantalum coating layer 72. Referring to FIG. 11A, the fourth tantalum coating layer 72 has a laminated structure including a fourth tantalum layer 76, a fourth tantalum carbide layer 77, and a fourth tantalum silicide layer 78, which are laminated in this order from the wafer body 71 side. You may do so. Such a structure is preferably applied when the wafer body 71 is made of a material other than tantalum.

The fourth tantalum layer 76 includes a pure Ta layer (a Ta layer with a purity of 99% or more). The fourth tantalum carbide layer 77 may have a single layer structure or a laminated structure including at least one of a Ta ₂ C layer 77a and a TaC layer 77b. In this embodiment, the fourth tantalum carbide layer 77 has a stacked structure including a Ta ₂ C layer 77a and a TaC layer 77b stacked in this order from the wafer body 71 side.

The fourth tantalum silicide layer 78 includes a Ta _α Si _β C _γ layer. The fourth tantalum silicide layer 78 has a single-layer structure or a laminated structure including at least one of two TaSi layers, three Ta _{5 Si} layers, _a Ta ₂ Si layer, a Ta ₃ Si layer, and a Ta ₅ Si ₃ C _0.5 layer. It may have a structure.

It is preferable that the fourth tantalum silicide layer 78 has a single-layer structure or a laminated structure including one or both of _two TaSi layers and _three Ta ₅ Si layers. The fourth tantalum silicide layer 78 preferably has a thickness less than the thickness of the fourth tantalum carbide layer 77. Of course, the fourth tantalum silicide layer 78 may have a thickness greater than the thickness of the fourth tantalum carbide layer 77.

Referring to FIG. 11B, the fourth tantalum coating layer 72 may have a stacked structure including a fourth tantalum carbide layer 77 and a fourth tantalum silicide layer 78 stacked in this order from the wafer body 71 side. Such a structure is preferably applied when the wafer body 71 is made of tantalum.

As described above, the dummy wafer 70 is a jig used together with the SiC wafer 2 during heat treatment of the SiC wafer 2, and is mounted on the support unit 30 together with the SiC wafer 2. The dummy wafer 70 includes a wafer body 71 and a fourth tantalum coating layer 72 covering the wafer body 71. According to the fourth tantalum coating layer 72, C atoms can be taken in by causing the C atoms of the SiC wafer 2 to react with Ta atoms through the atmosphere in the processing space 13.

In particular, according to the dummy wafer 70, C atoms can be taken in at a position close to the SiC wafer 2 while mounted on the support unit 30. For example, by mounting the dummy wafer 70 on the support unit 30 so as to face the SiC wafer 2, C atoms can be taken in through the atmosphere interposed in the wafer space 79 between the SiC wafer 2 and the dummy wafer 70. This reduces the amount of C atoms remaining on the outer surface of the SiC wafer 2, thereby suppressing roughness of the outer surface of the SiC wafer 2 caused by C atoms. Therefore, the SiC wafer 2 can be heat-treated with high quality.

Specifically, the fourth tantalum coating layer 72 includes a fourth tantalum silicide layer 78 that covers the wafer body 71. According to this structure, the fourth tantalum silicide layer 78 can function as a Si supply source. That is, the fourth tantalum silicide layer 78 is heated simultaneously with the SiC wafer 2, thereby supplying Si vapor into the wafer space 79.

Si vapor generated from the fourth tantalum silicide layer 78 reacts with C atoms generated on the outer surface (first main surface 3, second main surface 4, and side surface 5) of the SiC wafer 2. As a result, C atoms are removed from the outer surface of the SiC wafer 2, and vapor containing Si ₂ C, SiC ₂ , etc. is generated within the wafer space 79. C atoms such as Si ₂ C and SiC ₂ in the wafer space 79 are incorporated into the fourth tantalum silicide layer 78 . Therefore, roughness on the outer surface of the SiC wafer 2 caused by C atoms can be appropriately suppressed.

The fourth tantalum coating layer 72 may include a fourth tantalum carbide layer 77 interposed between the wafer body 71 and the fourth tantalum silicide layer 78. According to this structure, the reaction rate in the SiC wafer 2 can be adjusted according to the compositions of the fourth tantalum carbide layer 77 and the fourth tantalum silicide layer 78.

Each of the embodiments described above can be implemented in other forms. For example, in each of the above-described embodiments, in a vertical heat treatment furnace having a structure in which a plurality of SiC wafers 2 are supported in multiple stages in the vertical direction with the first principal surface 3 (second principal surface 4) extending in the horizontal direction, , a furnace core tube 10 and a support unit 30 were applied. However, the furnace core tube 10 and the support unit 30 are not applied to a horizontal heat treatment furnace in which a plurality of SiC wafers 2 are supported in a row in the horizontal direction with the first principal surface 3 (second principal surface 4) extending in the vertical direction. It's okay.

In each of the above embodiments, the furnace core tube 10 includes the first tantalum coating layer 12, the first support plate 31 (second support plate 32) includes the second tantalum coating layer 35, and the support column 33 includes the third tantalum coating layer 40. It has been shown. However, a configuration may be adopted in which one or two of the first to third tantalum coating layers 12, 35, and 40 are not included.

In other words, a form having the first and second tantalum coating layers 12 and 35 but not having the third tantalum coating layer 40 may be adopted. Further, a configuration may be adopted in which the first and third tantalum coating layers 12 and 40 are provided, but the second tantalum coating layer 35 is not provided. Further, a configuration may be adopted in which the second and third tantalum coating layers 35 and 40 are provided, but the first tantalum coating layer 12 is not provided.

Furthermore, a configuration may be adopted in which the first tantalum coating layer 12 is provided but the second and third tantalum coating layers 35 and 40 are not provided. Further, a configuration may be adopted in which the second tantalum coating layer 35 is provided but the first and third tantalum coating layers 12 and 40 are not provided. Further, a configuration may be adopted in which the third tantalum coating layer 40 is provided but the first and second tantalum coating layers 12 and 35 are not provided.

Further, when the dummy wafer 70 including the fourth tantalum coating layer 72 is applied, a configuration in which one, two, or three of the first to third tantalum coating layers 12, 35, and 40 are not included is adopted. It's okay.

In each of the above-described embodiments, when a gas containing Si (for example, silane gas (SiH ₄ )) is supplied from the gas supply unit 51 to the processing space 13, in the reactor core tube 10, the first tantalum silicide layer 20 does not have the first A tantalum coating layer 12 may be employed.

In this case, the first tantalum coating layer 12 may have a single layer structure or a laminated structure including either or both of the first tantalum layer 18 and the first tantalum carbide layer 19. Furthermore, if the tube body 11 includes tantalum exposed from the inner wall 14 or if the tube body 11 is made of tantalum, a core tube 10 without the first tantalum coating layer 12 may be employed.

Similarly, in each of the above-described embodiments, when a gas containing Si (for example, silane gas (SiH ₄ )) is supplied to the processing space 13 from the gas supply unit 51, in the first support plate 31 (second support plate 32), A second tantalum coating layer 35 without the second tantalum silicide layer 38 may be employed.

In this case, the second tantalum coating layer 35 may have a single layer structure or a laminated structure including either or both of the second tantalum layer 36 and the second tantalum carbide layer 37. Further, when the plate main body 34 includes tantalum exposed from the outer surface or when the plate main body 34 is made of tantalum, the first support plate 31 (second support plate 32) without the second tantalum coating layer 35 is used. Good too.

Similarly, in each of the above-described embodiments, when a gas containing Si (for example, silane gas (SiH ₄ )) is supplied from the gas supply unit 51 to the processing space 13, the pillar 33 does not have the third tantalum silicide layer 45. A third tantalum coating layer 40 may be employed.

In this case, the third tantalum coating layer 40 may have a single layer structure or a laminated structure including either one or both of the third tantalum layer 43 and the third tantalum carbide layer 44. Further, when the pillar body 39 includes tantalum exposed from the outer surface or when the pillar body 39 is made of tantalum, the pillar 33 without the third tantalum coating layer 40 may be employed.

Similarly, in each of the above-described embodiments, when a gas containing Si (for example, silane gas (SiH ₄ )) is supplied from the gas supply unit 51 to the processing space 13, the dummy wafer 70 does not have the fourth tantalum silicide layer 78. A fourth tantalum coating layer 72 may be employed.

In this case, the fourth tantalum coating layer 72 may have a single layer structure or a laminated structure including either one or both of the fourth tantalum layer 76 and the fourth tantalum carbide layer 77. Further, when the wafer body 71 includes tantalum exposed from the outer surface or when the wafer body 71 is made of tantalum, a dummy wafer 70 without the fourth tantalum coating layer 72 may be employed.

Examples of features extracted from this specification and drawings are shown below. Hereinafter, alphanumeric characters in parentheses represent corresponding components in each of the embodiments described above, but this is not intended to limit the scope of each item (Clause) to the embodiments.

[A1] A tube body (11, 61) and a tantalum coating layer (12) covering said inner wall (14).

[A2] The reactor core tube (10) according to A1, wherein the tantalum coating layer (12) includes a tantalum silicide layer (20) covering the inner wall (14).

[A3] The tantalum silicide layer (20) includes at least one of _two TaSi layers, _three Ta ₅ Si layers, a Ta ₂ Si layer, a Ta ₃ Si layer, and a Ta ₅ Si ₃ C _0.5 layer. The furnace core tube (10) described in A2.

[A4] The reactor core tube (10) according to A2 or A3, wherein the tantalum coating layer (12) includes a tantalum carbide layer (19) interposed between the inner wall (14) and the tantalum silicide layer (20). ).

[A5] The furnace tube (10) according to A4, wherein the tantalum carbide layer (19) includes at least one of a Ta ₂ C layer (19a) and a TaC layer (19b).

[A6] The reactor core tube (10) according to A4 or A5, wherein the tantalum coating layer (12) includes a tantalum layer (18) interposed between the inner wall (14) and the tantalum carbide layer (19). .

[A7] The tube body (11, 61) is made of at least one of carbon (C), molybdenum (Mo), tantalum (Ta), tungsten (W), and silicon carbide (SiC). The furnace core tube (10) according to any one of A1 to A6.

[A8] The core tube (10) according to any one of A1 to A7, wherein the tube body (11) has a single tube structure.

[A9] The tube body (61) includes an inner tube (62) and an outer tube (63), and has the inner wall (14) constituted by the inner tube (62) and the outer tube (63). The furnace core tube (10) according to any one of A1 to A7, having a tube structure.

[A10] The reactor core tube (10) according to A9, wherein the tantalum coating layer (12) has a portion that covers an inner wall portion of the inner tube (62).

[A11] The furnace core tube (10) according to A9 or A10, wherein the tantalum coating layer (12) has a portion that covers an inner wall portion of the outer tube (63).

[A12] The tube body (11, 61) has the processing space (13) in which a plurality of silicon carbide wafers (2) are accommodated, according to any one of A1 to A11. Hearth tube (10).

[A13] The core tube (10) according to any one of A1 to A12, wherein the tube body (11, 61) is formed into a longitudinal cylindrical shape.

[A14] The furnace tube (10) according to any one of A1 to A13, wherein the silicon carbide wafer (2) includes a hexagonal SiC single crystal.

[A15] The furnace tube (10) according to A14, wherein the silicon carbide wafer (2) includes a 4H-SiC single crystal.

[A16] The furnace tube (10) according to A14 or A15, wherein the silicon carbide wafer (2) has an off-angle.

[A17] The furnace tube (10) according to any one of A14 to A16, wherein the silicon carbide wafer (2) has a mark indicating the crystal orientation of the SiC single crystal.

[A18] The furnace core tube (10) according to any one of A1 to A17, wherein the silicon carbide wafer (2) has a diameter of 2 inches or more and 12 inches or less.

[A19] The furnace tube (10) according to any one of A1 to A18, wherein the silicon carbide wafer (2) has a thickness of 100 μm or more and 1100 μm or less.

[A20] The reactor core tube (10) according to any one of A1 to A19, wherein the silicon carbide wafer (2) has a laminated structure including a silicon carbide substrate and a silicon carbide epitaxial layer.

[B1] The reactor core tube (10) according to any one of A1 to A20 is configured to be housed in the processing space (13) while supporting the silicon carbide wafer (2). A heat treatment apparatus (1A, 1B) including a support unit (30) and a heating unit (53) arranged around the furnace core tube (10).

[B2] The heat treatment apparatus (1A, 1B) according to B1, wherein the support unit (30) includes a column (33) having a support portion (41) that supports the silicon carbide wafer (2).

[B3] The heat treatment apparatus (1A, 1B) according to B2, wherein the support portion (41) is a notch-shaped slit (42).

[B4] The pillar (33) includes a pillar main body (39) having a heat-resistant temperature higher than the heat-resistant temperature of the silicon carbide wafer (2), and a pillar-side tantalum coating layer (40) that covers the pillar main body (39). ) The heat treatment apparatus (1A, 1B) according to B2 or B3.

[B5] The heat treatment apparatus (1A, 1B) according to B4, wherein the pillar-side tantalum coating layer (40) includes a pillar-side tantalum silicide layer (45) that covers the pillar body (39).

[B6] The pillar-side tantalum silicide layer (45) includes at least one of _two TaSi layers, _three Ta ₅ Si layers, a Ta ₂ Si layer, a Ta ₃ Si layer, and a Ta ₅ Si ₃ C _0.5 layer. The heat treatment apparatus (1A, 1B) according to B5.

[B7] The pillar-side tantalum coating layer (40) includes a pillar-side tantalum carbide layer (44) interposed between the pillar body (39) and the pillar-side tantalum silicide layer (45), B5 or B6. The heat treatment apparatus (1A, 1B) described in .

[B8] The heat treatment apparatus (1A, 1B) according to B7, wherein the pillar-side tantalum carbide layer (44) includes at least one of a Ta ₂ C layer (45a) and a TaC layer (45b).

[B9] The pillar-side tantalum coating layer (40) includes a pillar-side tantalum layer (43) interposed between the pillar body (39) and the pillar-side tantalum carbide layer (44), according to B7 or B8. The heat treatment apparatus (1A, 1B) described.

[B10] The pillar body (39) is made of at least one of carbon (C), molybdenum (Mo), tantalum (Ta), tungsten (W), and silicon carbide (SiC), B4~ The heat treatment apparatus (1A, 1B) according to any one of B9.

[B11] The support unit (30) includes a support plate (31, 32) and the support column (33) connected to the support plate (31, 32), according to any one of B2 to B10. Heat treatment equipment (1A, 1B).

[B12] The support plate (31, 32) includes a plate body (34) having a heat resistance temperature higher than the heat resistance temperature of the silicon carbide wafer (2), and a support-side tantalum coating that covers the plate body (34). The heat treatment apparatus (1A, 1B) according to B11, comprising a layer (35).

[B13] The heat treatment apparatus (1A, 1B) according to B12, wherein the supporting tantalum coating layer (35) includes a supporting tantalum silicide layer (38) that covers the plate main body (34).

[B14] The supporting tantalum silicide layer (38) includes at least one of _two TaSi layers, _three Ta ₅ Si layers, a Ta ₂ Si layer, a Ta ₃ Si layer, and a Ta ₅ Si ₃ C _0.5 layer. The heat treatment apparatus (1A, 1B) according to B13, including:

[B15] The supporting tantalum coating layer (35) includes a supporting tantalum carbide layer (37) interposed between the plate body (34) and the supporting tantalum silicide layer (38), B13 or B14. The heat treatment apparatus (1A, 1B) described in .

[B16] The heat treatment apparatus (1A, 1B) according to B15, wherein the supporting tantalum carbide layer (37) includes at least one of a Ta ₂ C layer (37a) and a TaC layer (37b).

[B17] The supporting tantalum coating layer (35) includes a supporting tantalum layer (36) interposed between the plate body (34) and the supporting tantalum carbide layer (37), in B15 or B16. The heat treatment apparatus (1A, 1B) described.

[B18] The plate main body (34) is made of at least one of carbon (C), molybdenum (Mo), tantalum (Ta), tungsten (W), and silicon carbide (SiC), B12~ The heat treatment apparatus (1A, 1B) according to any one of B17.

[B19] The support unit (30) further includes a lid unit (25) configured to open and close the reactor core tube (10), and the support unit (30) is configured such that the lid unit (25) closes the reactor core tube (10). The heat treatment apparatus (1A, 1B) according to any one of B1 to B18, wherein the heat treatment apparatus (1A, 1B) is arranged on the lid unit (25) so as to be accommodated in the treatment space (13) in a state of being accommodated in the treatment space (13).

[B20] A heat retention unit (26) disposed on the lid unit (25) so that the lid unit (25) is accommodated in the processing space (13) with the reactor core tube (10) closed. The support unit (30) is arranged above the heat retention unit (26) so that the lid unit (25) is accommodated in the processing space (13) with the reactor core tube (10) closed. The heat treatment apparatus (1A, 1B) according to B19, which is located at.

[B21] Any of B1 to B20, further including a transport unit (50) that transports the support unit (30) into the processing space (13) and transports the support unit (30) from the processing space (13). The heat treatment apparatus (1A, 1B) described in one of the above.

[B22] B1 to B21, further including a gas supply unit (51) that supplies a processing gas to the processing space (13), and a gas exhaust unit (52) that exhausts the processing gas from the processing space (13). The heat treatment apparatus (1A, 1B) according to any one of (1A, 1B).

[C1] A pillar main body (39) having a heat resistance temperature higher than the heat resistance temperature of the silicon carbide wafer (2) and having a support part (41) that supports the silicon carbide wafer (2), and the pillar main body (39) a support unit (30) comprising a strut (33) having a tantalum coating layer (40) covering the strut (33);

[C2] The support unit (30) according to C1, wherein the support portion (41) is a notch-shaped slit (42).

[C3] The support unit (30) according to C1 or C2, wherein the tantalum coating layer (40) includes a tantalum silicide layer (45) that covers the pillar body (39).

[C4] The support unit (30) according to any one of C1 to C3 further includes a support plate (31, 32), and the support column (33) is connected to the support plate (31, 32). ).

[C5] The support plate (31, 32) includes a plate body (34) having a heat-resistant temperature higher than the heat-resistant temperature of the silicon carbide wafer (2), and a support-side tantalum coating that covers the plate body (34). Support unit (30) according to C4, comprising a layer (35).

[D1] Support plate (31, 32) having a plate body (34) having a heat resistance temperature higher than the heat resistance temperature of the silicon carbide wafer (2), and a tantalum coating layer (35) covering the plate body (34). and a support unit (33) connected to the support plate (31, 32) and having a support part (41) for supporting the silicon carbide wafer (2).

[D2] The support unit (30) according to D1, wherein the tantalum coating layer (35) includes a tantalum silicide layer (38) covering the plate body (34).

[E1] A dummy wafer (70) that is used together with the silicon carbide wafer (2) during heat treatment of the silicon carbide wafer (2), and has a wafer body ( 71); and a tantalum coating layer (72) covering said wafer body (71).

[E2] The dummy wafer (70) according to E1, wherein the tantalum coating layer (72) includes a tantalum silicide layer (78) covering the wafer body (71).

[E3] The tantalum silicide layer (78) includes at least one of _two TaSi layers, _three Ta ₅ Si layers, a Ta ₂ Si layer, a Ta ₃ Si layer, and a Ta ₅ Si ₃ C _0.5 layer. Dummy wafer (70) described in E2.

[E4] The dummy wafer (70) according to E2 or E3, wherein the tantalum coating layer (72) includes a tantalum carbide layer (77) interposed between the wafer body (71) and the tantalum silicide layer (78). ).

[E5] The dummy wafer (70) according to E4, wherein the tantalum carbide layer (77) includes at least one of a Ta ₂ C layer (77a) and a TaC layer (77b).

[E6] The dummy wafer (70) according to E4 or E5, wherein the tantalum coating layer (72) includes a tantalum layer (76) interposed between the wafer body (71) and the tantalum carbide layer (77). .

[E7] The wafer body (71) is made of at least one of carbon (C), molybdenum (Mo), tantalum (Ta), tungsten (W), and silicon carbide (SiC), E1 to A dummy wafer (70) according to any one of E6.

Although the embodiments have been described in detail above, these are merely specific examples to clarify the technical contents. Various technical ideas extracted from this specification can be appropriately combined without being limited by the order of explanation or the order of embodiments in the specification.

1A Heat treatment apparatus 1B Heat treatment apparatus 2 SiC wafer 10 Furnace tube 11 Tube body 12 First tantalum coating layer 13 Processing space 14 Inner wall 18 First tantalum layer 19 _First tantalum carbide layer 19a Ta2C layer 19b TaC layer 20 First tantalum silicide Layer 25 Lid unit 26 Heat retention unit 30 Support unit 31 First support plate 32 Second support plate 33 Support column 34 Plate body 35 Second tantalum coating layer 36 Second tantalum layer 37 Second tantalum carbide layer 37a Ta ₂ C layer 37b TaC layer 38 Second tantalum silicide layer 39 Pillar body 40 Third tantalum coating layer 41 Support part 42 Slit 43 Third tantalum layer 44 Third tantalum carbide layer 44a Ta ₂ C layer 44b TaC layer 45 Third tantalum silicide layer 50 Transport unit 51 Gas Supply unit 52 Gas exhaust unit 53 Heating unit 61 Tube body 62 Inner tube 63 Outer tube 70 Dummy wafer 71 Wafer body 72 Fourth tantalum coating layer 76 Fourth tantalum layer 77 Fourth tantalum carbide layer 77a Ta ₂ C layer 77b TaC layer 78 4 tantalum silicide layer

Claims (20)

1. a tube body having an inner wall that partitions a processing space in which a silicon carbide wafer is accommodated, and having a heat resistance temperature higher than the heat resistance temperature of the silicon carbide wafer;
   a tantalum coating layer covering the inner wall.
2. The reactor core tube according to claim 1, wherein the tantalum coating layer includes a tantalum silicide layer covering the inner wall.
3. 3 . The tantalum silicide layer includes at least one of a TaSi ₂ layer, a Ta ₅ Si ₃ layer, a Ta ₂ Si layer, a Ta ₃ Si layer, and a Ta ₅ Si ₃ C _0.5 layer. Furnace tube.
4. The furnace tube according to claim 2 or 3, wherein the tantalum coating layer includes a tantalum carbide layer interposed between the inner wall and the tantalum silicide layer.
5. The furnace tube of claim 4, wherein the tantalum carbide layer includes at least one of a _Ta2C layer and a TaC layer.
6. Any one of claims 1 to 5, wherein the tube body is made of at least one of carbon (C), molybdenum (Mo), tantalum (Ta), tungsten (W), and silicon carbide (SiC). The furnace core tube described in paragraph 1.
7. The reactor core tube according to any one of claims 1 to 6, wherein the tube body has a single tube structure.
8. The tube body according to any one of claims 1 to 6 has a multi-tube structure including an inner tube and an outer tube, and the inner wall is constituted by the inner tube and the outer tube. Furnace tube.
9. The furnace core tube according to any one of claims 1 to 8,
   a support unit configured to be accommodated in the processing space while supporting the silicon carbide wafer;
   A heating unit disposed around the furnace core tube.
10. The heat treatment apparatus according to claim 9, wherein the support unit includes a column having a support portion that supports the silicon carbide wafer.
11. The heat treatment apparatus according to claim 10, wherein the support portion comprises a support groove.
12. The heat treatment apparatus according to claim 10 or 11, wherein the pillar includes a pillar main body having a heat resistant temperature equal to or higher than the heat resistant temperature of the silicon carbide wafer, and a pillar side tantalum coating layer covering the pillar main body.
13. The heat treatment apparatus according to claim 12, wherein the pillar body is made of at least one of carbon (C), molybdenum (Mo), tantalum (Ta), tungsten (W), and silicon carbide (SiC). .
14. The heat treatment apparatus according to claim 12 or 13, wherein the pillar-side tantalum coating layer includes a pillar-side tantalum silicide layer that covers the pillar body.
15. a lid unit configured to open and close the reactor core tube;
    further comprising a heat retention unit disposed on the lid unit so that the lid unit is accommodated in the processing space with the reactor core tube closed;
    The support unit according to any one of claims 9 to 14, wherein the support unit is arranged on the heat retention unit so that the lid unit is accommodated in the processing space with the reactor core tube closed. Heat treatment equipment.
16. The heat treatment apparatus according to any one of claims 9 to 15, further comprising a transport unit that transports the support unit into the processing space and transports the support unit from the processing space.
17. a gas supply unit that supplies processing gas to the processing space;
    The heat processing apparatus according to any one of claims 9 to 16, further comprising a gas exhaust unit that exhausts processing gas from the processing space.
18. a pillar body having a heat-resistant temperature higher than the heat-resistant temperature of a silicon carbide wafer and having a support portion that supports the silicon carbide wafer;
    A support unit comprising: a column having a tantalum coating layer covering the column body.
19. 19. The support unit according to claim 18, wherein the support portion includes a notch-shaped slit.
20. The support unit according to claim 18 or 19, wherein the tantalum coating layer includes a tantalum silicide layer covering the pillar body.

Images