JP7367541B2 - Method for manufacturing silicon carbide polycrystalline substrate - Google Patents

Description

The present invention relates to a method for manufacturing a silicon carbide polycrystalline substrate.

Silicon carbide (hereinafter sometimes referred to as "SiC") is a compound semiconductor material composed of silicon and carbon. Compared to silicon (hereinafter sometimes referred to as "Si"), silicon carbide has a dielectric breakdown field strength 10 times that of silicon and a band gap three times that of silicon, making it an excellent semiconductor material. . Furthermore, single-crystal silicon carbide has recently begun to be used as a substrate material for power devices because it is possible to control p-type and n-type over a wide range, which is necessary for device fabrication.

However, compared with silicon carbide semiconductors, which have been widely used in the past, it is difficult to obtain a silicon carbide single crystal substrate with a large area, and the manufacturing process is also complicated. For these reasons, silicon carbide semiconductors are difficult to mass produce and are expensive compared to silicon semiconductors.

Various efforts have been made to reduce the cost of silicon carbide semiconductors. For example, Patent Document 1 discloses a method for manufacturing a silicon carbide substrate, in which at least a silicon carbide single crystal substrate and a silicon carbide polycrystalline substrate having a density of micropipes of 30 pieces/cm ² or less are prepared, and the silicon carbide It is described that a step of bonding a single crystal substrate and the silicon carbide polycrystalline substrate is performed, and then a step of thinning the single crystal substrate is performed to manufacture a substrate in which a single crystal layer is formed on the polycrystalline substrate. ing.

Furthermore, Patent Document 1 discloses that before the step of bonding the single crystal substrate and the polycrystalline substrate, a step of implanting hydrogen ions into the single crystal substrate to form a hydrogen ion implantation layer is performed, and the single crystal substrate and the polycrystalline substrate are bonded together. After the process of bonding with the crystal substrate and before the process of thinning the single crystal substrate, heat treatment is performed at a temperature of 350°C or less, and the process of thinning the single crystal substrate is mechanically performed using a hydrogen ion implantation layer. A method for manufacturing a silicon carbide substrate is described, which includes a step of peeling off the substrate.

With this method, more silicon carbide bonded substrates can be obtained from one silicon carbide single crystal ingot.

JP2009-117533A Japanese Patent Application Publication No. 2000-169298

However, most of the silicon carbide substrates manufactured by the method of Patent Document 1 are polycrystalline substrates. Therefore, in order to prevent the silicon carbide substrate manufactured by the method of Patent Document 1 from being damaged during handling such as polishing, it is necessary to use a silicon carbide polycrystalline substrate with a sufficient thickness to have mechanical strength. There is.

Conventionally, the silicon carbide polycrystalline substrate described above has been produced by forming a silicon carbide polycrystalline film on a support substrate made of carbon or the like slightly larger than the same diameter so as to have a desired diameter by chemical vapor deposition, and then The supporting substrate is exposed from the side by grinding, and the silicon carbide polycrystalline film is separated by destroying part or all of the supporting substrate by means such as baking in an oxidizing atmosphere, and then surface grinding and A silicon carbide polycrystalline substrate having a desired thickness and surface condition has been obtained by polishing (for example, see Patent Document 2). However, performing the process of grinding and polishing silicon carbide, which has high hardness, has been a cause of low production efficiency of silicon carbide polycrystalline substrates.

Therefore, an object of the present invention is to provide a method for manufacturing a silicon carbide polycrystalline substrate, which can reduce the grinding work of silicon carbide and improve the production efficiency of the silicon carbide polycrystalline substrate.

The method for manufacturing a silicon carbide polycrystalline substrate of the present invention includes a first laminate including a support substrate and a silicon carbide polycrystalline film formed on a surface of the support substrate to be film-formed by chemical vapor deposition. , a cutting step of cutting out a plurality of second laminates having a predetermined shape, and a removing step of removing the support substrate from the second laminate to obtain a silicon carbide polycrystalline substrate.

Moreover, in the method for manufacturing a silicon carbide polycrystalline substrate of the present invention, in the cutting step, the second laminate having the same shape and area may be cut out.

Furthermore, in the method for manufacturing a silicon carbide polycrystalline substrate of the present invention, the support substrate may have a circular shape in plan view.

Moreover, in the method for manufacturing a silicon carbide polycrystalline substrate of the present invention, the surfaces to be film-formed may be both surfaces of the support substrate.

The method for manufacturing a silicon carbide polycrystalline substrate of the present invention further includes a film forming step of forming the silicon carbide polycrystalline film on the film forming target surface of the supporting substrate before the cutting step, In one film forming step, the silicon carbide polycrystalline film may be formed on a plurality of supporting substrates.

Further, in the method for manufacturing a silicon carbide polycrystalline substrate of the present invention, in the film forming step, a plurality of the supporting substrates are held in a film forming apparatus so that the film forming target surfaces face each other, and the adjacent supporting substrates are The dimension between the supporting substrates may be 20 mm or more.

Furthermore, in the method for manufacturing a silicon carbide polycrystalline substrate of the present invention, a silicon carbide polycrystalline substrate having a diameter of 10 cm to 20 cm may be manufactured.

With the method for manufacturing a silicon carbide polycrystalline substrate of the present invention, it is possible to reduce the grinding work of silicon carbide and improve the production efficiency of the silicon carbide polycrystalline substrate.

FIG. 2 is a plan view showing a support substrate used in the method for manufacturing a silicon carbide polycrystalline substrate according to the present embodiment. FIG. 1 is a cross-sectional view schematically showing an example of a film forming apparatus used in the method for manufacturing a silicon carbide polycrystalline substrate according to the present embodiment. 3(A) is a side view showing the holding state of the supporting substrate at the point H shown in FIG. 2, FIG. 3(A) is the holding state of the supporting substrate in this embodiment, and FIG. 3(B) is the holding state of the supporting substrate in the conventional method It is a figure showing a state. FIG. 2 is a cross-sectional view schematically showing a support substrate, a silicon carbide polycrystalline film, and a silicon carbide polycrystalline substrate in each step of the method for manufacturing a silicon carbide polycrystalline substrate according to the present embodiment. FIG. 2 is a cross-sectional view schematically showing a supporting substrate, a silicon carbide polycrystalline film, and a silicon carbide polycrystalline substrate in each step of a conventional method for manufacturing a silicon carbide polycrystalline substrate. It is a top view which shows the modification of a support board.

[Method for manufacturing silicon carbide polycrystalline substrate]
A method for manufacturing a silicon carbide polycrystalline substrate according to an embodiment of the present invention will be described with reference to the drawings. The silicon carbide polycrystalline substrate obtained by the method for manufacturing a silicon carbide polycrystalline substrate of this embodiment can be used as a substrate for a power device, for example, by bonding it with a silicon carbide single crystal substrate.

The method for manufacturing a silicon carbide polycrystalline substrate according to the present embodiment includes a film forming step of forming a silicon carbide polycrystalline film 200 on film formation target surfaces 110 and 120 of a supporting substrate 100 by chemical vapor deposition, and 100 and a silicon carbide polycrystalline film 200, a plurality of second laminates 400 having a predetermined shape are cut out from the first laminate 300, and the supporting substrate 100 is removed from the second laminate 400. and a removing step of obtaining a silicon carbide polycrystalline substrate 500. Hereinafter, the method for manufacturing a silicon carbide polycrystalline substrate according to the present embodiment will be described in the order of a film forming process, a cutting process, and a removing process.

(Film forming process)
The following explanation is an example of a film forming process, and conditions such as temperature, pressure, gas atmosphere, etc., procedures, etc. may be changed within a range that causes no problems.

In this embodiment, the support substrate 100 shown in FIGS. 1 and 4A, for example, can be used as the support substrate. Note that FIG. 4(A) is a cross-sectional view taken along line AA in FIG. The support substrate 100 is made of carbon and preferably has a parallel flat plate shape, that is, a parallel flat plate in which the film-forming surfaces 110 and 120 correspond to the front surface and the back surface, as shown in the drawing. can. In this specification, "parallel" in a parallel plate includes not only strict parallelism but also cases where there is an unavoidable error in creating parallel surfaces of the support substrate 100.

Further, the support substrate 100 has a film formation target surface 110 (front surface) on which the silicon carbide polycrystalline film 200 is formed, a film formation target surface 120 (back surface), and four second laminate forming parts 130. , has. Further, it is preferable that the surfaces on which the silicon carbide polycrystalline film 200 is formed are both surfaces of the support substrate, like the support substrate 100 of this embodiment. As a result, twice the number of silicon carbide polycrystalline substrates can be obtained in one film forming process compared to the case where the film is formed on one side.

Further, the shape of the support substrate 100 is not particularly limited, and may be circular in plan view as shown in FIG. 1, or may be polygonal. However, in order to suppress unbalanced deposition of silicon carbide polycrystalline film 200 and in consideration of handling properties, it is preferable that support substrate 100 has a circular shape in plan view, that is, a disk shape. Further, the thickness of the support substrate 100 can be set to about 5 mm, for example, in consideration of suppressing deformation of the support substrate 100.

Further, the second laminate forming part 130 is a part where the polycrystalline silicon carbide film 200 is formed on the support substrate 100 and then separated in a cutting process to be described later. The second laminate forming part 130 forms a second laminate 400 together with the silicon carbide polycrystalline film 200 (FIG. 4(C)), and the second laminate forming part 130 is removed from the second laminate 400. becomes a silicon carbide polycrystalline substrate 500 (FIG. 4(D)). In addition, in the support substrate 100, as shown in FIG. Two of them are provided at positions rotated by 90 degrees from the body forming part 130, a total of four.

In addition, when manufacturing a plurality of silicon carbide polycrystalline substrates 500 having the same shape and the same area, from the viewpoint of production efficiency, the support substrate 100 is preferably has a plurality of second laminate forming parts 130.

Further, the size and shape of second laminate forming section 130 correspond to the size and shape of silicon carbide polycrystalline substrate 500 to be manufactured.

Further, in general, it is easy to form a thick polycrystalline silicon carbide film on the outer peripheral portion of the support substrate. For this reason, it is preferable to obtain the silicon carbide polycrystalline substrate 500 from the silicon carbide polycrystalline film 200 formed, for example, about 4 mm to 5 mm inward from the outer peripheral edge of the supporting substrate 100. It is preferable to set the size of the support substrate 100 in consideration of the surplus.

In the method for manufacturing a silicon carbide polycrystalline substrate of this embodiment, the manufactured silicon carbide polycrystalline substrate 500 can have a diameter of, for example, about 10 cm to 20 cm. At this time, the size of the support substrate 100 is specifically, when the support substrate 100 is circular in plan view, the support substrate for manufacturing a silicon carbide polycrystalline substrate 500 with a diameter of 4 inches (diameter 101 mm). The size of 100 can be, for example, a diameter of 210 mm or more (101 mm x 2 sheets + 4 mm surplus x 2). Further, the size of the support substrate 100 for manufacturing the silicon carbide polycrystalline substrate 500 with a diameter of 6 inches (diameter 151 mm) may be, for example, 310 mm or more in diameter (151 mm x 2 pieces + 4 mm x 2 surplus). can.

Moreover, the number of silicon carbide polycrystalline substrates 500 to be manufactured from each of the film-forming target surfaces 110 and 120 is not particularly limited, and may be set as appropriate in consideration of the size of the film-forming apparatus and the production plan. For example, as shown in FIG. 1, four sheets may be produced from the surface 110 to be film-formed.

The film forming process of this embodiment is a process of forming a silicon carbide polycrystalline film 200 on the film forming target surfaces 110 and 120 of the support substrate 100 shown in FIG. 1 by chemical vapor deposition, for example, as follows. This can be performed using the film forming apparatus 1000 described in . As shown in FIG. 1, film formation target surfaces 110 and 120 of support substrate 100 each have an area that allows four silicon carbide polycrystalline substrates 500 to be obtained.

The film forming apparatus used in this embodiment is preferably of a hot wall type, and preferably has a structure in which gas supplied to the film forming apparatus in the film forming process flows in the vertical direction. As shown in FIG. 2, the film forming apparatus 1000 includes a casing 1010 serving as an exterior of the film forming apparatus 1000, a film forming chamber 1020 for forming a silicon carbide polycrystalline film 200 on a support substrate 100, and a film forming chamber 1020. An exhaust gas introduction chamber 1050 that introduces source gas and carrier gas discharged from the gas into a gas exhaust port 1040 (described later), a box 1060 that covers the exhaust gas introduction chamber 1050, and a box 1060 that heats the inside of the film forming chamber 1020 from outside the box 1060. A heater 1070 made of carbon, a gas inlet 1030 that is provided at the upper part of the film forming chamber 1020 and introduces raw material gas and carrier gas into the film forming chamber 1020, a gas outlet 1040, and a support substrate 100 is held. It has a substrate holder 1080.

Further, the substrate holder 1080 includes a rod-shaped holding member 1081 and a holding pedestal 1082 that fixes the holding member 1081 in the film forming chamber 1020. Further, the holding pedestals 1082 are provided at two locations inside the side wall of the film forming chamber 1020, and the holding pedestals 1082 have holes (not shown) in which the holding members 1081 can be inserted and fixed. , the longitudinal direction of the rod-shaped holding member 1081 can be held horizontally. Further, in the holding member 1081, a portion where the support substrate 100 is held is threaded for fastening nuts N1 and N2, which will be described later. That is, as shown in FIG. 2, in the film forming apparatus 1000, the supporting substrate 100 is sandwiched and fixed using the nuts N1 and N2, so that the film forming surfaces 110 and 120 are vertically aligned with the holding member 1081. is maintained so that The above-described work of fixing the supporting substrate 100 to the substrate holder 1080 of the film forming chamber 1020 is generally performed manually.

Note that the method of holding the support substrate is not particularly limited. For example, the support substrate may be held so that the film-forming surfaces 110 and 120 are in the horizontal direction, but it may be held so that the silicon carbide polycrystalline film 200 is formed more uniformly. In addition, as in this embodiment, the support substrate 100 is arranged so that the film-forming surfaces 110 and 120 are vertical, that is, the normal to the surface of the support substrate 100 is perpendicular to the direction in which the supplied gas flows. It is preferable to keep it at .

Further, the number of supporting substrates 100 held in the film forming chamber 1020 is not particularly limited, and may be one or more. It is more preferable to use a plurality of sheets because production efficiency improves. That is, it is preferable to form the silicon carbide polycrystalline film 200 on a plurality of supporting substrates 100 in one film forming process. Further, film formation on one support substrate 100 may be performed multiple times (multiple batches), or film formation may be performed on a plurality of support substrates 100 multiple times (multiple batches).

Regarding the method of holding the support substrate 100, a hole is provided near the center of the film-forming surfaces 110 and 120 of the support substrate 100, and after inserting the holding member 1081 into this hole, nuts N1 and N2 are inserted. It may be fixed using

In the film-forming process, when a plurality of support substrates 100 are held in the film-forming apparatus 1000 so that the surfaces to be film-formed face each other as in this embodiment, the dimensions between adjacent support substrates 100 is preferably 20 mm or more. If the dimension between adjacent support substrates 100 is too small, the support substrates 100 may be damaged due to handling errors or the like during the work of installing the support substrates 100 in the film forming apparatus 1000. There is no particular upper limit to the size between adjacent support substrates 100, and it can be set as appropriate in consideration of the number of support substrates 100 to be installed, the dimensions of the film forming apparatus 1000, and the like.

In addition, in order to make the flow of gas between the substrates uniform, the dimensions between the inner wall of the film forming chamber 1020 and the support substrate 100 installed at the end, and the dimensions between adjacent support substrates 100 are adjusted. , are preferably equally spaced. As a result, even when a plurality of support substrates 100 are used in one film formation process, it is possible to reduce unevenness in film formation.

Further, when a plurality of support substrates 100 are installed in the film forming apparatus 1000, it is preferable to install the support substrates 100 at equal intervals in order to reduce unevenness in film formation and to form a film uniformly.

The specific procedure of the film forming process will be explained. First, while holding the support substrate 100 in the film forming chamber 1020, in order to remove the atmosphere from the film forming chamber 1020, the inside of the film forming chamber 1020 is evacuated using a rotary pump or the like, and then an inert gas such as Ar is used. The pressure is returned to atmospheric with gas, and the support substrate 100 is heated by the heater 1070 to the reaction temperature for film formation under an inert gas atmosphere. The temperature at which the silicon carbide polycrystalline film is formed can be, for example, approximately 1000°C to 1400°C. When the reaction temperature for film formation is reached, the supply of the inert gas is stopped, and a source gas and a carrier gas containing the components of the silicon carbide polycrystalline film 200 are supplied into the film formation chamber 1020.

The source gas is not particularly limited as long as it can form the silicon carbide polycrystalline film 200, and Si-based source gas and C-based source gas that are generally used for forming a silicon carbide polycrystalline film are used. be able to. For example, as the Si-based raw material gas, silane (SiH ₄ ) can be used, as well as monochlorosilane (SiH ₃ Cl), dichlorosilane (SiH ₂ Cl ₂ ), trichlorosilane (SiHCl ₃ ), and tetrachlorosilane (SiCl ₄ ) A chlorine-based Si raw material-containing gas (chloride-based raw material) containing Cl that has an etching effect can be used. As the C-based source gas, for example, hydrocarbons such as methane (CH ₄ ), propane (C ₃ H ₈ ), acetylene (C ₂ H ₂ ), etc. can be used. In addition to the above, trichloromethylsilane (CH ₃ Cl ₃ Si), trichlorophenylsilane (C ₆ H ₅ Cl ₃ Si), dichloromethylsilane (CH ₄ Cl ₂ Si), dichlorodimethylsilane ((CH ₃ ) ₂ SiCl ₂ ), chlorotrimethylsilane ((CH ₃ ) ₃ SiCl), and other organic silicon compounds may be subjected to reductive thermal decomposition in the gas phase.

Further, as the carrier gas, a commonly used carrier gas can be used as long as it can spread the raw material gas to the support substrate 100 without inhibiting the formation of the silicon carbide polycrystalline film 200. For example, H ₂ gas, which has excellent thermal conductivity and has an etching effect on silicon carbide, can be used as the carrier gas. Further, an impurity doping gas can be supplied as a third gas simultaneously with these source gas and carrier gas. For example, if the conductivity type of the silicon carbide polycrystalline substrate obtained by separating the silicon carbide polycrystalline film 200 from the support substrate 100 is n-type, nitrogen (N ₂ ) is used, and if the conductivity type is p-type, trimethylaluminum is used. (TMA) can be used.

When forming the silicon carbide polycrystalline film 200, the above gases are appropriately mixed and supplied. Further, depending on the desired properties of polycrystalline silicon carbide film 200, conditions such as the gas mixture ratio and supply amount may be changed during the film forming process.

Silicon carbide polycrystalline films 200 can be formed on both surfaces of the heated support substrate 100 by a chemical reaction on the surface of the support substrate 100 or in the gas phase. The thickness of silicon carbide polycrystalline film 200 can be appropriately set in consideration of the desired thickness of silicon carbide polycrystalline substrate 500, and can be, for example, about 300 μm to 1000 μm. Through the above film-forming process, as shown in FIG. 4(B), a first laminate 300 of the support substrate 100 and the silicon carbide polycrystalline film 200 is formed, in which the silicon carbide polycrystalline film 200 is formed on the support substrate 100. is obtained. The first laminate 300 formed as described above is cooled to about room temperature and then subjected to a cutting process.

(Cutting process)
The cutting process is a process of separating a plurality of second laminates 400 having a predetermined shape from a first laminate 300 consisting of support substrate 100 and polycrystalline silicon carbide film 200 .

Here, the second laminate 400 is a laminate of the second laminate forming portion 130 of the support substrate 100 and the silicon carbide polycrystalline film 200. Further, the predetermined shape is a shape corresponding to the shape of silicon carbide polycrystalline substrate 500 to be manufactured, and can be any shape, such as a circular shape or a polygonal shape. Although the size of the second laminate 400 is not particularly limited, the second laminate 400 usually has the same size as the silicon carbide polycrystalline substrate to be manufactured, or the size of the silicon carbide polycrystalline substrate 500 after the removal process described below. In consideration of the process of grinding the outer peripheral portion to adjust the diameter to a desired size, the size is slightly larger (for example, about several millimeters) than the final silicon carbide polycrystalline substrate. Due to the high hardness of silicon carbide, rather than obtaining a second laminate that is significantly larger than the silicon carbide polycrystalline substrate to be manufactured, it is preferable to obtain a second laminate having a size comparable to that of the silicon carbide polycrystalline substrate to be manufactured. It is preferable to obtain.

Further, the plurality of second laminates 400 may all have the same size and the same shape, or may have different sizes or different shapes.

In addition, in the cutting process, after observing the film thickness distribution of the first laminate 300 of the support substrate 100 and the silicon carbide polycrystalline film 200 obtained in the film forming process, the second laminate 400 is separated. You can decide the location.

A cutting tool equipped with a rotary blade or the like can be used to separate the second stacked body 400. For example, it can be cut into a predetermined shape using a cutting tool having a disc-shaped rotating blade. Furthermore, since the silicon carbide polycrystalline substrate 500 is generally formed in a circular shape, a core drill that cuts the object to be cut in a circular shape can be suitably used to separate the second laminate 400. .

When a core drill is used in the cutting process, the dimensions of the core drill can be set to correspond to the desired silicon carbide polycrystalline substrate. In this embodiment, as shown in FIG. 4(B), with the first laminate 300 as the object to be cut, each silicon carbide polycrystalline film 200 formed on the second laminate forming part 130 of the support substrate 100, The second laminate 400 (FIG. 3(C)) can be obtained by cutting with a core drill (M1, M2 in FIG. 3(B)). In addition, when using a core drill, since the cut inner part is used as the second laminate 400 in a later process, processing is performed using only a drill (core bit) for cutting into a circular shape, without using a center drill. be able to. By using a core drill in the cutting process, workability can be improved when obtaining the circular second laminate 400.

Through the above cutting process, a second laminate 400 shown in FIG. 4(C) is obtained. The obtained second laminate 400 is subjected to a removal process.

(Removal process)
The removal step is a step of removing second laminate forming portion 130 of support substrate 100 from second laminate 400 to obtain silicon carbide polycrystalline substrate 500 . The second laminate forming part 130 is heated in an oxidizing gas atmosphere such as O ₂ or air at several hundred degrees (for example, about 800°C) for 100 hours or more to burn only the second laminate forming part 130. , can be removed. Since the second laminate 400 is obtained by separating the first laminate 300, the side surface of the second laminate forming part 130 is exposed. A slicing process may be performed in which the second laminate forming portion 130 is sliced at the line C in 4(C). By performing the slicing process on the second laminate 400, the exposed area of the second laminate forming part 130 becomes larger, and the second laminate forming part 130 can be burned and removed more efficiently. Through the above steps, a silicon carbide polycrystalline substrate 500 (FIG. 4(D)) is obtained.

Further, after the removal step, diameter processing, chamfering, thickness processing, flatness processing, and cleaning are performed as necessary. Diameter machining or chamfering is a process in which the outer circumferential portion is ground using a diamond grindstone, etc. to adjust the desired diameter dimension, and at the same time, the corners of the entire outer circumferential portion of the silicon carbide polycrystalline substrate are removed. . In addition, thickness processing and flatness processing refer to grinding or polishing on the film-forming surface in order to achieve a thickness and flatness suitable for applications such as manufacturing bonded substrates with silicon carbide single crystal substrates. It is used to adjust the thickness and flatness.

Grinding and polishing to adjust the thickness and flatness can be performed, for example, by lapping the silicon carbide polycrystalline substrate 500 with diamond slurry, hard polishing with a mixed slurry of diamond and alumina, and then lapping with silica slurry (colloidal silica). , pH 11). Thereby, the thickness of silicon carbide polycrystalline substrate 500 can be adjusted, the flatness can be increased, and the surface of silicon carbide polycrystalline substrate 500 can be smoothed.

[Conventional method for manufacturing silicon carbide polycrystalline substrate]
Here, a conventional method for manufacturing a silicon carbide polycrystalline substrate will be described with reference to FIG. 5. In the conventional method for manufacturing a silicon carbide polycrystalline substrate, a silicon carbide polycrystalline film 200E is formed on a supporting substrate 100E (FIG. 5(A)) having the same size as the silicon carbide polycrystalline substrate to be manufactured, and a laminate 300E ( After obtaining the silicon carbide polycrystalline substrate (FIG. 5(B)), if necessary, the outer circumferential portion of the supporting substrate 100E is exposed, for example at the line E in FIG. 5(B), and the supporting substrate 100E is removed. 500E (FIG. 5(C)).

In the vicinity of the outer peripheral edge (outer peripheral portion) of the support substrate, the thickness of the deposited polycrystalline silicon carbide film tends to increase. In the conventional method for manufacturing a silicon carbide polycrystalline substrate, a silicon carbide polycrystalline film formed on the entire surface of the support substrate is used as the silicon carbide polycrystalline substrate, so that even in the obtained silicon carbide polycrystalline substrate, the outer peripheral portion The thickness tends to increase. In other words, since the difference in film thickness within the same plane of the obtained silicon carbide polycrystalline substrate tends to be large, after removing the supporting substrate, the film-forming surface is ground and polished to improve the thickness and flatness. It takes more time to adjust.

Specifically, when a 1000 μm silicon carbide polycrystalline film is formed and a 400 μm silicon carbide polycrystalline substrate is finally obtained by grinding, the film thickness distribution is approximately 1000 μm±600 μm. The film thickness is about 700 μm±300 μm on the inside of the surface of the supporting substrate to be film-formed, while the film thickness is about 1300 μm±300 μm at the outer peripheral portion of the surface to be film-formed. In other words, in the grinding process after removing the support substrate, the carbonization with high hardness is flattened from about 1600 μm to 400 μm, for example, to the line F in FIG. 5(B), and then processed to adjust the thickness. There were times when silicon had to be ground, and the grinding process was a heavy burden.

[Comparison between the manufacturing method of this embodiment and the conventional manufacturing method]
On the other hand, in the method for manufacturing a silicon carbide polycrystalline substrate of the present embodiment, the outer peripheral portion of the silicon carbide polycrystalline film 200 that is likely to be thicker is avoided among the silicon carbide polycrystalline film 200 formed on the support substrate 100. Thus, the second laminate 400 can be obtained. Thereby, a silicon carbide polycrystalline substrate 500 with a small difference in film thickness within the same plane can be manufactured. Therefore, with the method for manufacturing a silicon carbide polycrystalline substrate of this embodiment, it is possible to reduce the grinding work of silicon carbide and improve the production efficiency of the silicon carbide polycrystalline substrate.

In addition, in the conventional method for manufacturing a silicon carbide polycrystalline substrate, since the conventional method for manufacturing a silicon carbide polycrystalline substrate uses a supporting substrate 100E having the same size as the silicon carbide polycrystalline substrate to be manufactured, a single silicon carbide polycrystalline substrate is used. Two silicon carbide polycrystalline substrates 500E are obtained from support substrate 100E when both surfaces of support substrate 100E are used as surfaces to be film-formed. On the other hand, in the case of the method for manufacturing a silicon carbide polycrystalline substrate of this embodiment, when using the support substrate 100 shown in FIG. 1, eight silicon carbide polycrystalline substrates 500 are obtained from both sides of the support substrate 100.

FIG. 3 is a diagram showing a state in which a supporting substrate is installed in the substrate holder 1080 of the film forming apparatus 1000, FIG. 3(A) shows the state in the method of this embodiment, and FIG. 3(B) shows the state in the conventional method. FIG. When manufacturing the same number of silicon carbide polycrystalline substrates, when comparing the conventional manufacturing method and the manufacturing method of this embodiment, it is found that in the manufacturing method of this embodiment (FIG. 3(A)), The number of supporting substrates 100 to be installed is smaller than that of the conventional method (FIG. 3(B)).

Therefore, in the manufacturing method of this embodiment, the dimension between adjacent support substrates 100 (dimension R in FIG. 3(B)) is smaller than the dimension between conventional support substrates (dimension r in FIG. 3(B)). It is possible to suppress damage to the support substrate due to handling errors and the like, and improve yield, compared to conventional manufacturing methods. Furthermore, by reducing the number of supporting substrates 100 to be installed, it is possible to reduce the chances of damage to the supporting substrates 100 and the first laminate 300 due to handling errors, etc., and to improve work efficiency.

Further, in the conventional method for manufacturing a silicon carbide polycrystalline substrate, a support substrate of 4 inches to 6 inches with a thickness of about 1 mm is sometimes used in order to suppress the manufacturing cost of the support substrate. In such a case, since the thickness is thin, the support substrate may be damaged during the work of attaching the support substrate. However, in the method for manufacturing a silicon carbide polycrystalline substrate according to the present embodiment, a silicon carbide polycrystalline substrate that is thicker than conventional ones (for example, about 5 mm) is used in consideration of the strength of the support substrate itself, so that the attachment of the support substrate is difficult. Damage to the supporting substrate can be suppressed during operation compared to the conventional method.

Furthermore, when a plurality of supporting substrates are installed in the film forming chamber 1020, the thickness of the film formed may be uneven at the ends of the film forming chamber 1020, which may reduce the yield rate of manufactured silicon carbide polycrystalline substrates. be. Therefore, with the method of this embodiment, the number of support substrates 100 to be installed can be reduced, and therefore, the support substrates 100 can be installed avoiding locations where uneven film formation occurs, such as the edges of the film formation chamber 1020. As a result, the yield rate of silicon carbide polycrystalline substrates can be improved and the yield rate can be improved.

Furthermore, if the number of support substrates installed in the film forming apparatus 1000 is the same in the manufacturing method of this embodiment and the conventional manufacturing method, in the manufacturing method of this embodiment, multiple Since silicon carbide polycrystalline substrates can be manufactured, the number of silicon carbide polycrystalline substrates that can be obtained by the manufacturing method of this embodiment is greater. From this, the manufacturing method of this embodiment can improve the production efficiency of silicon carbide polycrystalline substrates.

As explained above, the method for manufacturing a silicon carbide polycrystalline substrate of this embodiment can improve production efficiency and work efficiency compared to conventional methods, thereby reducing manufacturing costs. be able to.

Note that the present invention is not limited to the embodiments described above, and includes other configurations that can achieve the object of the present invention, and the present invention also includes the following modifications.

In the embodiment described above, a method of manufacturing a plurality of silicon carbide polycrystalline substrates 500 of the same size from the support substrate 100 was illustrated, but it is also possible to manufacture silicon carbide polycrystalline substrates of different sizes from the support substrate. good. In consideration of manufacturing efficiency, the support substrate 100A used when manufacturing silicon carbide polycrystalline substrates of different sizes has different sizes on the same plane (for example, the film-forming target surface 110), as shown in FIG. The second laminate forming section 130A corresponds to the production of a 6-inch silicon carbide polycrystalline substrate, and the second laminate formation section 130A corresponds to the production of a 4-inch silicon carbide polycrystalline substrate. It is preferable to have a body forming part 130B). Thereby, silicon carbide polycrystalline substrates of different sizes can be obtained without adjusting the size by significantly grinding the outer periphery of the silicon carbide polycrystalline substrate obtained by the removal process.

Further, in the method for manufacturing a silicon carbide polycrystalline substrate described above, the silicon carbide polycrystalline substrate is manufactured through a film formation process, a cutting process, and a removal process. The silicon carbide polycrystalline substrate 500 may be manufactured by obtaining the first laminate 300 on which the silicon carbide polycrystalline film 200 is formed and performing only the cutting process and the removal process.

In addition, the best configuration, method, etc. for carrying out the present invention have been disclosed in the above description, but the present invention is not limited thereto. That is, although the present invention has been specifically described mainly with respect to specific embodiments, there may be changes in shape, material, quantity, Various modifications can be made by those skilled in the art in other detailed configurations. Therefore, the descriptions that limit the shapes, materials, etc. disclosed above are provided as examples to facilitate understanding of the present invention, and do not limit the present invention. Descriptions of names of members that exclude some or all of the limitations such as these are included in the present invention.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited to these Examples in any way.

In this example, a silicon carbide polycrystalline film 200 is formed using a hot wall type film forming apparatus 1000 that holds the support substrate 100 of the above-described embodiment on a holding member 1081 and introduces a film forming gas from the bottom. After performing the film forming process, a cutting process was performed using a core drill. Furthermore, the support substrate (second laminate forming part 130) was removed from the obtained second laminate 400 to obtain a silicon carbide polycrystalline substrate 500. In addition, the thickness of the polycrystalline silicon carbide film formed in the film formation process was set to 1000 μm, and after removing the supporting substrate in the removal process, the obtained polycrystalline silicon carbide substrate was subjected to a grinding process. , the thickness was adjusted to 400 μm.

(Example 1)
A graphite support substrate with a diameter of 400 mm and a thickness of 5 mm was used as the support substrate. Six of these supporting substrates were installed in the substrate holder 1080 in the film forming chamber 1020 of the film forming apparatus 1000. Specifically, the nut N1 and the nut N2 are inserted into the holding member 1081, the support board is positioned between the nut N1 and the nut N2, and then the support board is fastened by tightening the nut N1 and the nut N2. Fixed. This operation was repeated six times to fix six supporting substrates.

In addition, it was attempted to obtain 48 silicon carbide polycrystalline substrates from 6 supporting substrates, with both surfaces of the supporting substrates being subjected to film formation. At this time, the dimensions between the inner wall of the film-forming chamber 1020 and the supporting substrate 100 installed at the end, and the dimension between the opposing surfaces of adjacent supporting substrates to be film-formed were fixed to 20 mm. The time required to hold the six supporting substrates in the film forming chamber was 5 minutes. Further, there were no cracks in the supporting substrates due to handling errors during holding work in the film forming chamber.

First, a film formation process was performed. After the inside of the film forming chamber 1020 was evacuated using an exhaust pump (not shown), the pressure was returned to atmospheric pressure using Ar gas, and then heated to 1400° C. SiCl ₄ and CH ₄ were used as source gases, and H ₂ was used as a carrier gas. The silicon carbide polycrystalline film was formed by mixing the above gases at a flow rate ratio of SiCl ₄ :CH ₄ :H ₂ :N ₂ =1:1:10 and supplying the mixture into the film forming chamber 1020 for 2.5 hours. Film formation was carried out. At this time, the pressure inside the film forming chamber was controlled to be 20 kPa.

Next, a cutting process was performed. From the laminate of the support substrate and the polycrystalline silicon carbide film obtained in the film forming process, one first laminate to four second laminates are formed using a core drill with an inner diameter of φ151 mm equipped with diamond abrasive grains. The body was separated. At this time, the second laminate was separated leaving 4 mm of the outer periphery of the laminate. The time required for the cutting process was 8 minutes on average for one second laminate. In the obtained second laminate, the support substrate was exposed at the outer peripheral portion.

Further, the second laminate was heated in the air at 800° C. for 100 hours to remove the supporting substrate by firing. As a result, a total of eight silicon carbide polycrystalline substrates were obtained from the four second laminates. The remaining five first laminates were also subjected to the same process, and as a result, six supporting substrates were subjected to the film forming process, resulting in a total of 48 silicon carbide polycrystalline substrates. That is, in the manufacturing process, there was no damage such as cracking, and the expected number (48 pieces) of silicon carbide polycrystalline substrates were obtained.

Furthermore, the resulting silicon carbide polycrystalline substrate had an average thickness of 700 μm, with little difference in thickness within the same plane, and no grinding or polishing was required for flattening. The thickness of such a silicon carbide polycrystalline substrate was adjusted to 400 μm by grinding and polishing. The processing was performed by lapping the silicon carbide polycrystalline substrate with diamond slurry, hard polishing with a mixed slurry of diamond and alumina, and then polishing with silica slurry (colloidal silica, pH 11). The time required for grinding and polishing was 50 minutes on average for one silicon carbide polycrystalline substrate.

(Comparative example 1)
In the film forming process, a graphite substrate with a diameter of 151 mm and a thickness of 1 mm was used as a supporting substrate. The supporting substrates were formed on both sides, and 24 supporting substrates were used to obtain a total of 48 silicon carbide polycrystalline substrates. Furthermore, in Comparative Example 1, before the removal step, the silicon carbide on the outer peripheral portion of the laminate was ground to expose the support substrate. The time required to grind the silicon carbide to expose the support substrate was 15 minutes on average for each laminate.

In the film forming process, the dimensions between the inner wall of the film forming chamber 1020 and the supporting substrate 100 installed at the end, and the dimension between the opposing film forming surfaces of adjacent supporting substrates are fixed to be 10 mm. did. A silicon carbide polycrystalline substrate was manufactured in the same manner as in Example 1, except for the film forming conditions, grinding processing, and polishing processing conditions other than those described above. The time required to hold the 24 supporting substrates in the film forming chamber was 30 minutes. In addition, two supporting substrates were damaged due to handling errors during the work of holding them in the film forming chamber. Additionally, one silicon carbide polycrystalline substrate was damaged. The damage to the silicon carbide polycrystalline substrate was caused by mishandling during the work of holding the supporting substrate, and although the supporting substrate did not break, the supporting substrate was cracked, and carbonization occurred on the cracked supporting substrate. It was thought that this was due to the formation of a silicon polycrystalline film, which led to the cracking of the silicon carbide polycrystalline substrate. Through the above steps, 43 silicon carbide polycrystalline substrates were obtained. Furthermore, the obtained silicon carbide polycrystalline substrate had a large thickness at the outer peripheral portion (1300 μm on average), and was subjected to grinding and polishing in order to flatten it and further adjust the thickness to 400 μm. The time required for grinding and polishing was 150 minutes on average for one silicon carbide polycrystalline substrate.

With the method for manufacturing a silicon carbide polycrystalline substrate of Example 1, which is an exemplary embodiment of the present invention, it is possible to reduce the grinding work of silicon carbide and improve the production efficiency of the silicon carbide polycrystalline substrate. Furthermore, in terms of workability in handling the support substrate, it is possible to suppress damage to the support substrate due to handling errors, etc., and improve yield compared to conventional manufacturing methods. Further, by reducing the number of supporting substrates to be installed, work efficiency can be improved. From the above, the method for manufacturing a silicon carbide polycrystalline substrate of the present invention can improve production efficiency and work efficiency compared to conventional methods, thereby reducing manufacturing costs. .

100, 100A Support substrates 110, 120 Film-forming surfaces 130, 130A, 130B Second laminate forming section 200 Silicon carbide polycrystalline film 300 First laminate 400 Second laminate 500 Silicon carbide polycrystalline substrate

Claims (7)

Cutting out a plurality of second laminates having a predetermined shape from a first laminate consisting of a support substrate and a silicon carbide polycrystalline film formed on a film-forming surface of the support substrate by chemical vapor deposition; The cutting process and
a removing step of removing the supporting substrate from the second laminate to obtain a silicon carbide polycrystalline substrate ,
The method for manufacturing a silicon carbide polycrystalline substrate, wherein the cutting step is a step of exposing the support substrate of the second laminate from a side surface . The method for manufacturing a silicon carbide polycrystalline substrate according to claim 1, wherein in the cutting step, the second laminate having the same shape and the same area is cut out. The method for manufacturing a silicon carbide polycrystalline substrate according to claim 1 or 2, wherein the support substrate has a circular shape in plan view. The method for manufacturing a silicon carbide polycrystalline substrate according to any one of claims 1 to 3, wherein the surfaces to be film-formed are both surfaces of the support substrate. Further comprising a film forming step of forming the silicon carbide polycrystalline film on the film forming target surface of the supporting substrate before the cutting step,
5. The method for manufacturing a silicon carbide polycrystalline substrate according to claim 1, wherein the silicon carbide polycrystalline film is formed on a plurality of supporting substrates in one film forming step. In the film forming step, a plurality of the supporting substrates are held in a film forming apparatus such that the film forming target surfaces face each other, and a dimension between adjacent supporting substrates is 20 mm or more. Item 5. The method for manufacturing a silicon carbide polycrystalline substrate according to item 5. The method for manufacturing a silicon carbide polycrystalline substrate according to any one of claims 1 to 6, which comprises manufacturing a silicon carbide polycrystalline substrate having a diameter of 10 cm to 20 cm.

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