JP2022068478A - Film deposition device - Google Patents

Abstract

To provide a film deposition device which includes a rotary member of a film deposition object substrate, capable of being repeatedly used by suppressing breakage during film deposition.SOLUTION: A film deposition device includes: a film deposition chamber for forming a film on a film deposition object substrate by a chemical vapor deposition method; a raw material gas introduction port for introducing a raw material gas into the film deposition chamber; a raw material gas exhaust port for exhausting a raw material gas from the film deposition chamber; a rotary shaft for rotatably holding the film deposition object substrate; and rotation driving means for rotating the rotary shaft. The rotary shaft includes a first gear for receiving power transmitted from the rotation driving means. The rotation driving means includes a second gear that meshes with the first gear, for transmitting power. Each of the first gear and the second gear includes a plurality of tooth parts provided side by side in an annular manner, and a tooth bottom part for connecting between dedendums of the tooth parts. In the first gear and the second gear, each tooth part has a first silicon carbide layer formed on a surface of the tooth part.SELECTED DRAWING: Figure 5

Description

The present invention relates to a film forming apparatus, for example, a silicon carbide (hereinafter, may be referred to as “SiC”) polycrystal on a support substrate by a chemical vapor deposition method (hereinafter, may be referred to as “CVD method”). The present invention relates to a film forming apparatus capable of forming a film.

SiC is a compound semiconductor material composed of silicon (hereinafter, may be referred to as "Si") and carbon. SiC has an insulation breakdown electric field strength 10 times that of Si and an excellent bandgap of 3 times that of Si, and it is possible to control the p-type and n-type required for manufacturing devices in a wide range. Therefore, it is expected as a material for power devices that exceeds the limit of Si.

However, as compared with the widely used Si semiconductor, the SiC semiconductor cannot be mass-produced as compared with the Si semiconductor because a large-area SiC single crystal substrate cannot be obtained and the process is complicated, so that the SiC semiconductor is expensive. rice field.

Various measures have been taken to reduce the cost of SiC semiconductors. For example, Patent Document 1 describes a method for manufacturing a SiC substrate, in which at least a SiC single crystal substrate and a SiC polycrystalline substrate having a micropipe density of 30 pieces / cm2 or less are prepared, and the single crystal substrate and the polycrystal substrate are prepared. It is described that a substrate in which a single crystal layer is formed on a polycrystalline substrate is manufactured by performing a step of bonding with a crystalline silicon carbide substrate and then a step of thinning the single crystal substrate.

Further, in Patent Document 1, before the step of bonding the SiC single crystal substrate and the SiC single crystal substrate, a step of injecting hydrogen ions into the SiC single crystal substrate to form a hydrogen ion injection layer is performed to form a SiC single crystal substrate. After the step of bonding the crystal substrate and the SiC single crystal substrate, and before the step of thinning the SiC single crystal substrate, the step of performing heat treatment at a temperature of 350 ° C. or lower to thin the SiC single crystal substrate is hydrogen. A method for manufacturing a SiC substrate, which is a step of mechanically peeling off with an ion injection layer, is described.

By such a method, more SiC substrates can be obtained from one SiC single crystal ingot.

Japanese Unexamined Patent Publication No. 2009-117533 Patent No. 3857446

However, most of the SiC bonded substrates manufactured by the method described in Patent Document 1 are SiC polycrystalline substrates. Therefore, it is necessary to use a SiC polycrystalline substrate having a sufficient thickness so that the SiC bonded substrate is not damaged during handling such as polishing and has mechanical strength.

Conventionally, in the SiC polycrystalline substrate, a SiC polycrystalline film is formed on a large number of graphite-made support substrates (deposited substrates) by a CVD method, and then each support substrate coated with the SiC polycrystalline film is made of SiC. The support substrate is separated from the SiC polycrystalline film by means such as grinding the end face of the polycrystalline film to expose it from the side surface of the SiC polycrystalline film and then firing in an oxidizing atmosphere, and then the SiC polycrystalline film is flattened. By grinding and polishing if necessary, a SiC polycrystalline substrate having a desired thickness and surface condition was obtained (for example, Patent Document 2).

However, in the method described above, when a large number of support substrates are put into the film forming chamber of the CVD film forming apparatus to form a film, the film is formed due to the temperature distribution in the film forming chamber and the concentration gradient of the film forming gas. There is a possibility that the film thickness of the SiC polycrystal film will vary greatly, and this variation will result in a longer film formation process and an increase in the amount of grinding during surface grinding of the SiC polycrystal film after film formation. It was a factor that lowered the productivity of the polycrystal film and increased the manufacturing cost.

Further, for example, in order to make the film thickness uniform, it is conceivable to install a support substrate holder having a rotation shaft for rotating the support substrate in the film forming chamber. In this case, if the parts that rotate the support substrate, such as the rotating shaft, are damaged during film formation and the rotation of the support substrate stops, it becomes difficult to make the thickness of the film formed uniform, and the productivity of the substrate increases. May decrease. Further, from the viewpoint of the cost of the parts, it is desirable that the parts can be used not only once but repeatedly many times. From the above, strength is required for the parts constituting the rotation driving means for rotating the support substrate.

Therefore, an object of the present invention is to provide a film forming apparatus provided with a rotation driving means of a film forming target substrate, which can be used repeatedly while suppressing damage during film forming.

The film forming apparatus of the present invention has a film forming chamber for forming a film on a substrate to be formed by a chemical vapor phase growth method, a raw material gas introduction port for introducing a raw material gas into the forming chamber, and a raw material gas from the forming chamber. A raw material gas discharge port for discharging the The rotary drive means has a second gear that meshes with the first gear to transmit power, and the first gear and the second gear are annularly formed. It has a plurality of tooth portions provided side by side and a tooth bottom portion connecting between the tooth roots of the tooth portions, and in the first gear and the second gear, the tooth portions are the tooth portions, respectively. It has a first silicon carbide layer formed on the surface of the.

In the film forming apparatus of the present invention, each of the tooth bottom portions has a second silicon carbide layer formed on the surface of the tooth bottom portion, and the first silicon carbide layer and the second silicon carbide layer are integrally integrated. There may be.

In the film forming apparatus of the present invention, the thickness of the first silicon carbide layer may be 200 μm to 1000 μm.

In the film forming apparatus of the present invention, the rotation shaft and the rotation driving means may be made of graphite.

The film forming apparatus of the present invention further includes a raw material gas introduction port for introducing the raw material gas into the film forming chamber and a raw material gas discharging port for discharging the raw material gas from the film forming chamber, and the rotating shaft is the same. In the film forming chamber, between the raw material gas introduction port and the raw material gas discharge port, the longitudinal direction is arranged so as to be orthogonal to the flow direction of the raw material gas, and the raw material gas is rotated in the flow direction. The film-forming target substrate may be held so as to be rotatable in the direction in which the raw material gas flows and the film-forming target surface of the film-forming target substrate is parallel to the flow direction of the raw material gas.

In the film forming apparatus of the present invention, since the strength of the first gear and the second gear that mesh with each other becomes high, damage during film formation of the member constituting the rotation driving means for rotating the film forming target substrate is suppressed. Can be used repeatedly.

It is a schematic diagram which shows an example of a mode in which a wafer-shaped film-forming target substrate 100 is held by a rotating shaft 200 during film-forming. It is a schematic diagram which shows an example of a mode in which a plurality of wafer-shaped film-forming target substrates 100 are held by a rotating shaft 200 during film formation. It is a schematic diagram which shows an example of the aspect which is different from FIG. It is a schematic diagram which shows an example of the aspect which is different from FIG. It is a schematic sectional drawing of the film forming apparatus 1000 which concerns on one Embodiment of this invention. It is a schematic diagram which shows the structure of the gear in a gearbox 530. It is a figure which shows the deformation example of the gear shown in FIG. It is a figure which shows the cross section of the gear shown in FIG. It is a figure which shows the gear used in the comparative example 1. FIG.

[Film formation device]
The film forming apparatus according to the embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments.

The film-forming apparatus of the present embodiment can be applied to applications in which a film is formed on a film-forming target substrate (supporting substrate) by a chemical vapor deposition method to manufacture the substrate. The film forming apparatus of this embodiment can be suitably used for manufacturing, for example, a silicon carbide (SiC) substrate, a gallium nitride (GaN) substrate, and a silicon (Si) substrate. In the following, a case of manufacturing a silicon carbide polycrystalline substrate will be described as an example.

The film forming apparatus of the present embodiment is an apparatus capable of forming a thin film of a predetermined substance on the film forming target surface of the film forming target substrate by the chemical vapor deposition method. For example, a carbon support substrate can be used as a film-forming target substrate, and an arbitrary silicon carbide polycrystalline film or silicon carbide single crystal film can be formed on these support substrates.

Such a film forming apparatus includes the following film forming chamber, raw material gas introduction port, raw material gas discharge port, rotary shaft, and rotary drive means.

<Membrane formation room>
In the film forming chamber, a film-forming target substrate is installed in the room, and a thin film is formed on the film-forming target substrate by a chemical vapor deposition method. The internal shape of the film forming chamber can be any shape such as a rectangular parallelepiped shape or a cylindrical shape.

Further, the film forming chamber is preferably made of graphite. If graphite is used, it can be easily processed into a rectangular parallelepiped shape or a cylindrical shape, and by creating an inert atmosphere at the time of film formation, it is possible to have sufficient durability under high temperature film formation conditions.

The film forming chamber is provided with a raw material gas introduction port and a raw material gas discharge port, which will be described later. The arrangement portion of these ports is not particularly limited, but for example, if the raw material gas introduction port is on the floor of the film forming chamber and the raw material gas discharge port is on the ceiling of the film forming chamber, the raw material gas is placed during the film forming process. Flows from bottom to top in the vertical direction.

<Raw material gas inlet>
The raw material gas inlet introduces the raw material gas into the film forming chamber. For example, when forming a film on a carbon support substrate, Si-based gas and C-based gas may be introduced into the film forming chamber using separate raw material gas inlets, and a mixed gas in which these are mixed in advance may be introduced. It may be introduced into the film forming chamber. Further, the raw material gas is accompanied by the carrier gas and may be further accompanied by the dopant gas.

As the raw material gas introduction pipe having the raw material gas introduction port at the end, for example, when a carbon support substrate is formed, any pipe such as a graphite pipe or a stainless steel pipe can be used.

In addition, a temperature control means such as a heater that can appropriately heat the raw material gas introduction pipe and a cooler that can cool the raw material gas introduction pipe is provided so that the temperature of the raw material gas introduction port can be controlled so that the raw material does not precipitate and the raw material gas introduction port is not blocked. You may.

<Raw material gas outlet>
The raw material gas discharge port discharges the raw material gas from the film forming chamber. As the raw material gas discharge pipe having the raw material gas discharge port at the end, any pipe such as a graphite pipe or a stainless steel pipe can be used.

A temperature control means such as a heater that can appropriately heat the raw material gas discharge pipe and a cooler that can cool the raw material gas discharge pipe is provided so that the temperature of the raw material gas discharge port can be controlled so that the raw material does not precipitate and the raw material gas discharge port is not blocked. You may.

<Axis of rotation>
The rotation axis rotatably holds the film-forming target substrate in order to reduce the bias of the silicon carbide film formation on the film-forming target surface of the film-forming target substrate. In order to reduce the bias of film formation, the rotation axis rotates in the direction in which the raw material gas flows so that the film-forming target substrate can rotate in the direction in which the raw material gas flows, and the film-forming target surface of the film-forming target substrate. Is preferably held parallel to the flow direction of the raw material gas.

During the film forming process, the raw material gas flows from the raw material gas introduction port to the raw material gas discharge port in the film forming chamber. Therefore, when the film formation target surface of the film formation target substrate is held parallel to the flow direction of the raw material gas, the axis of rotation is longitudinally formed between the raw material gas introduction port and the raw material gas discharge port in the film formation chamber. The direction is arranged so as to be orthogonal to the direction in which the raw material gas flows. By arranging the rotation axes in this way, it becomes possible to rotate in the direction in which the raw material gas flows, and further, the film-forming target substrate can be rotated in the direction in which the raw material gas flows, and the film-forming target surface of the film-forming target substrate. Can be held parallel to the direction in which the raw material gas flows.

(Fixed part)
The rotating shaft may be provided with a fixing portion for skewering and fixing the film-forming target substrate. For example, threading is performed over the entire longitudinal direction of the rotating shaft body, and by passing this rotating shaft body through an opening opened in the center of the film forming target substrate, the film forming target substrate is skewered and further. The film-forming target substrate can be fixed by fastening the fixing members from both sides of the film-forming target substrate using a fixing member made of a nut or a washer.

For example, when forming a carbon support substrate, it is preferable that the rotating shaft body and the fixing member are made of graphite. If it is made of graphite, it can be easily threaded, nut-shaped or washer-shaped, and by creating an inert atmosphere during film formation, it has sufficient durability against high-temperature film formation conditions. Can have.

FIG. 1 shows a schematic view showing an example of a mode in which the wafer-shaped film-forming target substrate 100 is held by the rotary shaft 200 during film formation as an example of the mode of fixing the film-forming target substrate by the fixing portion.

The film-forming target substrate 100 has an opening 110 in which a rotation shaft 200 can be inserted, and has a front surface 120a and a back surface 120b which are film-forming target surfaces 120 of the film-forming target substrate 100. are doing.

In FIG. 1, the film-forming target substrate 100 has a rotating shaft 200 inserted through an opening 110, and is fastened to the rotating shaft 200 from the front surface 120a and the back surface 120b using two nuts 210 as fixing members. Is held by the rotating shaft 200.

As the rotary shaft 200 and the nut 210, materials that can withstand film formation by the chemical vapor deposition method can be used, and for example, a carbon rotary shaft 200 and the nut 210 can be used.

By rotating the rotation shaft 200 counterclockwise as shown by the arrow A, for example, the film-forming target substrate 100 can be rotated counterclockwise as shown by the arrow A. Further, the rotation direction of the rotation shaft 200 is not limited, and the rotation shaft 200 may be rotated clockwise.

The rotation speed of the film-forming target substrate during the film-forming process is not particularly limited, but can be set to, for example, 0.1 rpm to 60 rpm. If the rotation speed is slower than 0.1 rpm, the thickness of the film formed may be significantly uneven, and if it is faster than 60 rpm, the rotation shaft 200 may be damaged or an air flow may be generated due to rotation. There is a risk that the film will malfunction. Further, the front surface 120a and the back surface 120b of the film-forming target substrate 100 are the film-forming target surfaces 120, and the vector vertically exiting from the film-forming target surface 120 is defined as the surface normal line 300.

Further, the direction in which the raw material gas flows is indicated by an arrow B. The raw material gas is not particularly limited as long as a film can be formed, and a generally used raw material gas can be used. For example, when forming a polycrystalline film of silicon carbide, a Si-based raw material gas and a C-based raw material gas are used. As the Si-based raw material gas, for example, silane (SiH ₄ ) can be used, and a chlorine-based Si raw material-containing gas containing Cl having an etching action such as SiH ₃ Cl, SiH ₂ Cl ₂ , SiHCl ₃ , and SiCl ₄ . (Chloride-based raw material) can also be used. As the C-based raw material gas, for example, methane (CH ₄ ), propane (C ₃ H ₈ ), and acetylene (C ₂ H ₂ ) can be used.

When forming a polycrystalline film other than silicon carbide, another raw material gas can be used depending on the polycrystalline film to be formed. For example, when forming a silicon polycrystal film, monosilane gas, _SiH4 gas, or the like can be used. When forming a polycrystalline film of gallium nitride, trimethylgallium: Ga (CH ₃ ) ₃ gas, ammonia: NH ₃ gas and the like can be used.

Further, the raw material gas may be accompanied by a carrier gas. If the raw material gas can be spread on the film-forming target substrate 100 without inhibiting the film formation, a commonly used carrier gas can be used. For example, when forming a silicon carbide polycrystalline film, hydrogen (H ₂ ), which has excellent thermal conductivity and has an etching action on SiC, can be used.

Further, at the same time as these raw material gas and carrier gas, an impurity doping gas can be simultaneously supplied as a third gas. For example, nitrogen (N ₂ ) can be used when the conductive type is n-type, and trimethylaluminum (TMA) can be used when the p-type is used.

When forming a film with the film forming apparatus of the present embodiment, the surface normal line 300 of the film forming target surface 120 of the film forming target substrate 100 and the direction B in which the raw material gas flows are orthogonal to each other, and the surface normal line 300 is used. It is preferable to rotate the film-forming target substrate 100 in a direction in which the rotation axis 200 on which the film-forming target substrate 100 rotates is parallel to form a film. In this way, while rotating the film-forming target substrate 100, the raw material gas is supplied along the film-forming target surface 120 to form a film, so that the raw material gas is unevenly supplied to the film-forming target surface 120. Therefore, it is possible to suppress variations in the film thickness within the same surface of the film formation target surface 120 of the film formation target substrate 100.

The direction in which the raw material gas flows can be arbitrarily set. The direction in which the raw material gas flows may be, for example, a direction parallel to the film forming target surface 120, a vertical direction as shown by an arrow B in FIG. 1, or a horizontal direction.

Further, FIG. 2 shows a schematic view showing an example of a mode in which a plurality of wafer-shaped film-forming target substrates 100 are held on the rotating shaft 200 during film-forming. When forming a film with the film forming apparatus of the present invention, a method of forming a plurality of film forming target substrates 100 may be used as shown in FIG. By installing the number of film-forming target substrates 100 capable of forming a film in one process in the film-forming chamber of the film-forming apparatus, the film-forming efficiency can be improved.

Here, it is preferable that all of the central axes 130 of the plurality of film-forming target substrates 100 are installed so as to coincide with the rotating shaft 200 to form a film. That is, each of the film-forming target substrates 100 has an opening 110 in which the rotary shaft 200 can be inserted, and a plurality of film-forming target substrates are skewered by inserting the rotary shaft 200 through the opening 110. The 100 is arranged and fastened to and fixed to the rotating shaft 200 using a plurality of nuts 210. With such an arrangement, any of the central axes 130 of the plurality of film-forming target substrates 100 can be aligned with the rotation axis of the rotating shaft 200, and the film-forming conditions for any of the film-forming target substrates 100. Since it is possible to prevent the raw material gas from being unevenly supplied to any of the film forming target surfaces 120, the same surface of the film forming target surface 120 is formed on any of the film forming target substrates 100. It is possible to suppress the variation in the film thickness inside.

Then, as shown in FIG. 2, when a plurality of film-forming target substrates 100 are formed by one process, it is preferable that the distances 140 between the substrates of the plurality of film-forming target substrates 100 are evenly spaced. Since the distances 140 between the substrates are evenly spaced, the raw material gas can be uniformly and evenly supplied to any of the film-forming target surfaces 120, so that the film-forming target surface 120 of the film-forming target substrate 100 is in the same plane. The variation in film thickness can be further suppressed.

(Grip part)
The rotating shaft may include a gripping portion that grips the end portion of the film-forming target substrate. For example, as in the case of the above-mentioned fixing portion, thread cutting is performed over the entire longitudinal direction of the rotating shaft body, and further, using a gripping member consisting of a nut or a washer, the end portions thereof are formed from both sides of the substrate to be film-formed. By sandwiching and then fastening the gripping member, the end portion of the film-forming target substrate can be gripped. Further, instead of a nut or washer, a spacer having an opening through which the rotating shaft body is passed can be used as a gripping member, and the spacer can be used to grip the end of the substrate to be film-formed by sandwiching it from both sides. can.

For example, when a polycrystalline film is formed using a carbon support substrate, it is preferable that the rotating shaft body and the gripping member are made of graphite. If it is made of graphite, it can be easily threaded, nut-shaped or washer-shaped, and by creating an inert atmosphere during film formation, it has sufficient durability against high-temperature film formation conditions. Can have.

FIG. 3 shows, as an example of a mode of fixing the film-forming target substrate by the fixing portion, a mode different from that of FIG. 2 in which a plurality of wafer-shaped film-forming target substrates 100 are held by the rotary shaft 200 during film formation. A schematic diagram showing an example is shown. When forming a film with the manufacturing apparatus of the present invention, as shown in FIG. 3, by forming a plurality of film-forming target substrates 100, the number of film-forming target substrates that can be formed in one process is formed. By installing 100 in the film forming chamber of the film forming apparatus, the film forming efficiency can be improved. Further, in the case of the embodiment shown in FIG. 3, a plurality of film-forming target substrates 100 form a rotationally symmetric substrate group 400 in which the plurality of film-forming target substrates 100 are arranged rotationally symmetrically on the rotating shaft 200. Each film-forming target substrate 100 is gripped and fixed to the rotating shaft 200 by a pair of nuts 210 as fixing means. The fixing means is not particularly limited, but for example, in addition to the nut 210 that has been passed through, the film-forming target substrate 100 can be fixed by sandwiching and gripping the film-forming target substrate 100 with a washer or the like.

The rotationally symmetric substrate group 400 is composed of a plurality of film-forming target substrates 100 on the same plane, and FIG. 3 shows four film-forming target substrates 100, but the present invention is not limited to this, and 2 to 2 to A rotationally symmetric substrate group 400 can be formed by an arbitrary number of film-forming target substrates 100 with about eight sheets, and the rotationally symmetric substrate group 400 can be gripped and fixed to the rotation shaft 200 by a pair of nuts 210. By forming a rotationally symmetric substrate group 400 with a plurality of film-forming target substrates 100 and rotating the rotationally symmetric substrate group 400, the film-forming conditions can be made uniform for any of the film-forming target substrates 100. Therefore, it is possible to prevent the raw material gas from being unevenly supplied to any of the film formation target surfaces 120, so that the film thickness of the film formation target surface 120 in the same surface of any film formation target substrate 100 can be achieved. Variation can be suppressed.

Further, FIG. 4 shows a schematic view showing an example of a mode different from that of FIG. 3 in which a plurality of wafer-shaped film-forming target substrates 100 are held on the rotating shaft 200 during film formation. Here, it is preferable that all of the rotation axes 410 of the plurality of rotationally symmetric substrate groups 400 match. That is, the film-forming target substrate 100 of any of the rotationally symmetric substrate groups 400 is arranged to be fixed to the same rotating shaft 200. With such an arrangement, any of the rotation axes 410 of the plurality of rotationally symmetric substrate groups 400 can be matched with the rotation axis of the rotation axis 200, and the film formation conditions for any of the film formation target substrates 100. Since it is possible to prevent the raw material gas from being unevenly supplied to any of the film formation target surfaces 120, the same surface of the film formation target surface 120 can be prevented in any of the film formation target substrates 100. It is possible to suppress the variation in the film thickness inside.

Then, as shown in FIG. 4, when the film-forming target substrates 100 of the plurality of rotationally symmetric substrate groups 400 are formed by one process, the distances 420 between the substrates among the plurality of rotationally symmetric substrate groups 400 are evenly spaced. Is preferable. Since the distances 420 between the substrates are evenly spaced, the raw material gas can be uniformly and evenly supplied to any of the film-forming target surfaces 120, so that the film-forming target surface 120 of the film-forming target substrate 100 is in the same plane. The variation in film thickness can be further suppressed. It is possible to make the distances 420 between the boards evenly spaced, for example, by adjusting the width of the nut 210 or by using a spacer or the like in addition to the nut 210.

As described above, by performing the film formation while rotating the film-forming target substrate 100, it is possible to suppress the variation in the film thickness within the same surface of the film-forming target surface of the film-forming target substrate. As a result, productivity can be improved and manufacturing cost can be reduced by shortening the film forming time and reducing the amount of grinding in surface grinding.

<Rotation drive means>
The rotation driving means rotates the rotation axis that holds the film-forming target substrate. A motor can be used as the prime mover. As will be described later, the gears provided on the shaft extending from the motor and the gears provided on the rotating shaft mesh with each other to change the direction of rotation of the shaft and rotate the rotating shaft, thereby being held by the rotating shaft. The support substrate can be rotated.

In particular, when a member such as a shaft constituting the rotation driving means is provided in the film forming chamber, it is preferable that these members are made of graphite. If it is made of graphite, it is easy to process, and if it is made of graphite, it can have sufficient durability under high temperature film forming conditions by creating an inert atmosphere at the time of film formation. When the rotation driving means is provided outside the housing of the film forming chamber, it does not need to be a material that can cope with the film forming environment, and is generally made of metal, FRP, etc. under normal temperature and pressure in an atmospheric atmosphere. Any rotation driving means that can be used for

Here, if the components constituting the rotation driving means are damaged during film formation and the rotation of the film-forming target substrate is stopped, it becomes difficult to make the thickness of the film-formed film uniform, and the productivity of the substrate is lowered. I have something to do. Further, from the viewpoint of the cost of parts, it is desirable that the parts can be used not only once but repeatedly many times. From the above, the parts constituting the rotary drive means for rotating the support substrate, in particular, the first gear of the rotary shaft to which the most force is applied and the first gear of the shaft that meshes with the first gear of the rotary shaft to rotate the rotary shaft. Two gears are required to have strength. However, in order to apply it to the film forming environment in the film forming chamber, when the member including the first gear and the second gear constituting the rotation driving means is made of graphite, the strength that can be used over and over again is increased. It was difficult to hold it.

The rotation driving means in the film forming apparatus of the present embodiment has a rotating shaft having a first gear and a second gear that engages with the first gear to rotate the rotating shaft while holding the film forming target substrate. Further, in the first gear and the second gear, each tooth portion has a first silicon carbide layer formed on the surface of the tooth portion. As a result, the strength of the first gear and the second gear can be increased. From the above, even if the first gear and the second gear that mesh with each other are made of graphite, damage during film formation of the rotating member (rotary shaft and rotation driving means) that rotates the film-forming target substrate is suppressed. , The rotating member can be used repeatedly.

Further, the above-mentioned first gear and the second gear each further have a disk portion for holding the tooth portion, and the disk portion is formed on the surface of the disk portion, respectively, and the first silicon carbide layer is formed. It may have a second silicon carbide layer integrated with. Such a gear can be manufactured by forming a silicon carbide layer on the surface of a member in which a disk portion and a tooth portion are integrated. As a result, the strength of the rotating member becomes higher, and the rotating member can be used repeatedly while suppressing damage during film formation.

(Other configurations)
The film forming apparatus may be provided with a configuration other than the above. For example, a heater that controls the temperature in the film forming chamber, a water-cooled stainless steel housing that is outside the heater and is an exterior of the film forming apparatus, and the like can be provided.

(Film formation device 1000)
Hereinafter, the film forming apparatus according to the embodiment of the present invention will be described with reference to the drawings. FIG. 5 shows a schematic cross-sectional view of the film forming apparatus 1000 as the film forming apparatus according to the embodiment of the present invention.

The film forming apparatus 1000 is a hot wall type thermal CVD apparatus that introduces the raw material gas from the bottom surface of the film forming chamber 1010 and discharges it from the ceiling, and has a structure in which the raw material gas flows in the vertical direction. The film forming apparatus 1000 introduces the raw material gas and the carrier gas into the film forming chamber 1010 for forming the film forming target substrate 100 rotatably held on the rotating shaft 200 by using a plurality of nuts 210, and the film forming chamber 1010. The introduction port 1020, the exhaust port 1030 for exhausting the raw material gas and the carrier gas discharged from the film forming chamber 1010 to the outside of the film forming apparatus 1000, and the exhaust port 1030 for the raw material gas and the carrier gas discharged from the film forming chamber 1010. The exhaust gas introduction chamber 1040 to be introduced into the 1030, the box 1050 covering the exhaust gas introduction chamber, the heater 1060 that controls the temperature inside the film forming chamber 1010 from the outside of the box 1050, and the film forming apparatus outside the heater 1060. A water-cooled stainless steel housing 1100, which serves as an exterior of 1000, is provided.

Further, in the film forming apparatus 1000, as a rotation driving means for rotating the rotating shaft 200, the motor 500 grounded at the center of the upper part of the outer wall of the housing 1100, the shaft 520 is from the motor 500 to the housing 1100, the box 1050, and the exhaust gas. It penetrates the introduction chamber 1040 and extends into the film forming chamber 1010. Further, there is a gearbox 530 inside the film forming chamber 1010, and the rotation shaft 200 extends to the left and right from the gearbox 530 to hold the film forming target substrate 100 on the left and right of the gearbox 530. Further, both ends of the rotating shaft are fixed to the box 1050 by bearings 510.

The rotation speed of the rotating shaft 200 can be controlled by a switch or the like that can control the rotation speed, and the rotation can also be controlled by a mechanical or electrical control means such as a brake. Further, the end portion of the rotating shaft 200 opposite to the gearbox 530 is fixed to the box 1050 by a bearing 510 grounded to the outer wall of the box 1050 so as not to hinder the rotation of the rotating shaft 200.

FIG. 6 shows a schematic diagram showing the configuration of the gears in the gearbox 530. Inside the gearbox 530, a second gear 520a provided near the end of the shaft 520 and a first gear 200a provided on the rotating shaft 200 at a distance equal to or near both ends in the longitudinal direction thereof. Are provided so as to mesh with each other, and the horizontal rotation by the shaft 520 (arrow C) can be converted into the vertical rotation of the rotation shaft 200 (arrow D).

Further, in the present embodiment, the rotary shaft 200 and the shaft 520 are made of graphite. As a result, even if the gearbox 530 is provided in the film forming chamber 1010, it can be applied to the film forming environment.

Here, FIG. 8A is a cross-sectional view of the first gear 200a on a plane that passes through the central axes of all the tooth portions 201 of the first gear 200a and is parallel to the rotation direction of the rotation shaft 200. In FIG. 8A, the symbol R indicates the diameter of the tooth portion 201. The first gear 200a is a spur gear that receives power transmitted from a shaft 520 that is a rotation driving means.

As shown in FIGS. 6 and 8 (A), the first gear 200a is a columnar column provided on the surface of the rotating shaft 200 in the circumferential direction in an annular shape (8 in the present embodiment) arranged at equal intervals. It has a tooth portion 201 and a tooth bottom portion 203 connecting between the tooth roots 202 of the tooth portion 201. The tooth bottom portion 203 is formed in an annular shape as a whole. Further, each of the tooth portions 201 has a first silicon carbide layer 201a formed on the surface of the tooth portions 201. Further, the tooth bottom portion 203 has a second silicon carbide layer 203a formed on the surface of the tooth bottom portion 203, and the first silicon carbide layer 201a and the second silicon carbide layer 203a are integrated.

Further, FIG. 8B is a cross-sectional view of the second gear 520a on a plane that passes through the central axes of all the tooth portions 521 of the second gear 520a and is parallel to the rotation direction of the shaft 520. In FIG. 8B, the symbol r indicates the diameter of the tooth portion 521. The second gear 520a is a spur gear that meshes with the first gear 200a to transmit power.

As shown in FIGS. 6 and 8B, the second gear 520a is a columnar column provided on the surface of the shaft 520 in the circumferential direction in an annular shape (four in the present embodiment) arranged at equal intervals. It has a tooth portion 521 and a tooth bottom portion 523 connecting between the tooth roots 522 of the tooth portion 521. The tooth bottom 5233 is formed in an annular shape as a whole. Further, each of the tooth portions 521 has a first silicon carbide layer 521a formed on the surface of the tooth portion 521. Further, the tooth bottom portion 523 has a second silicon carbide layer 523a formed on the surface of the tooth bottom portion 523, and is integrated with the second silicon carbide layer 523a integrated with the first silicon carbide layer 521a.

As shown in FIG. 6, in the gearbox 530, the tooth portion 201 of the first gear 200a and the tooth portion 521 of the second gear 520a are in contact with each other, so that the first gear 200a and the second gear 520a are engaged with each other. (Rotation drive means) The power from the shaft 520 can be transmitted to the second gear 520a to rotate the rotary shaft 200.

In the present embodiment, the first gear 200a is configured as a gear having a large number of teeth, and the second gear 520a is configured as a pinion having a small number of teeth, but the size relationship of the gears is not particularly limited. Further, the shape of the gear, the configuration of the gear, and the like are not limited to this embodiment and can be changed as appropriate.

The thickness of the first silicon carbide layer and the second silicon carbide layer can be, for example, about 200 μm to 1000 μm. If it is too thin, it may have insufficient strength, and if it is too thick, it may deviate from the driveable mechanical dimensional tolerance. Therefore, by setting the above range, the strength of the first gear 200a and the second gear 520a can be sufficiently increased, and the deviation from the driveable mechanical dimensional tolerance can be suppressed.

Further, the method for forming the first silicon carbide layer and the second silicon carbide layer as described above is not particularly limited, but the first silicon carbide layer and the second silicon carbide layer are carbonized with respect to the member by the chemical vapor deposition method. It can be formed by forming a silicon polycrystal film.

For example, the film forming target substrate 100 is not installed in the film forming apparatus 1000, but the film forming apparatus 1000 is operated after installing the shaft and the rotating shaft without the silicon carbide layer (so-called idle operation of the film forming apparatus 1000). The first silicon carbide layer and the second silicon carbide layer may be formed by forming a silicon carbide polycrystal film on the surfaces of the second gear and the first gear. When forming the first silicon carbide layer and the second silicon carbide layer, it is desirable to mask the parts where the silicon carbide layer is unnecessary on the surface and remove the masking after forming the silicon carbide layer. The silicon carbide layer can be formed only at the location of.

In the film forming apparatus 1000, the shaft 520 is rotated by the drive of the motor by the rotary drive means including the motor 500, the shaft 520, the first gear 521 in the gearbox 530, and the second gear 201, and further, the rotation is further performed. The shaft 200 can be rotated.

In the above-described embodiment, the example in which the silicon carbide layer is formed on the entire surface of the first gear 200a and the second gear 520a is shown, but the silicon carbide layer may be formed only on the tooth portion. ..

FIG. 7 is a diagram showing a modified example of the gear in the gearbox 530 described above. The gear shown in FIG. 7 has a first gear 200b provided on the rotating shaft and a second gear provided on the shaft 520. Unlike the gear in the gearbox 530 described above (FIG. 6), the first gear 200b has only the first silicon carbide layer 201a formed on the surface of the tooth portion 201 as the silicon carbide layer, but the second carbide layer. It does not have a silicon layer 203a. Further, the second gear 520b has only the first silicon carbide layer 521a formed on the surface of the tooth portion 521 as the silicon carbide layer, but does not have the second silicon carbide layer 523a. As described above, since the portion where the force is most applied in the first gear and the second gear is the tooth portion 201 521, as shown in FIG. 7, the tooth portion 201 is applied to the first gear 200a and the second gear 520a. A silicon carbide layer (that is, only the first silicon carbide layers 201a and 521a) may be formed only on the 521.

In the film forming apparatus of the above-described embodiment, in order to prevent contamination of the substrate, it is possible to prevent substances other than the substances constituting the target substrate from being present in the film forming chamber. preferable. That is, when manufacturing a silicon carbide polycrystalline substrate, it is preferable not to use a substance other than silicon carbide and graphite or the like that can be removed after the film formation as a material constituting the film forming apparatus. Therefore, when a substrate other than silicon carbide such as a gallium nitride (GaN) substrate and a silicon (Si) substrate is manufactured by using the same film forming apparatus as the above-described embodiment, the gear in the gearbox has. A gallium nitride layer and a silicon layer can be provided instead of the silicon carbide layer.

[Example of substrate manufacturing method]
Next, an example of a method for manufacturing a substrate using the film forming apparatus of the above-described embodiment will be described. In the following description, a method for manufacturing a silicon carbide polycrystalline substrate by using the film forming apparatus 1000 shown in FIG. 5 will be exemplified.

First, in the film forming chamber 1010 of the film forming apparatus 1000 shown in FIG. 5, a plurality of film forming target substrates 100 are fixed to the rotating shaft 200. Then, in order to remove the atmosphere from the film forming chamber 1010, the inside of the film forming chamber 1010 is evacuated with a rotary pump or the like, and then the inside of the film forming chamber 1010 is returned to atmospheric pressure with an inert gas such as Ar to be inert. The temperature inside the film forming chamber 1010 is raised to the reaction temperature while flowing gas. When the inside of the film forming chamber 1010 reaches the reaction temperature, the inert gas is stopped, the motor 500 is moved to rotate the rotating shaft 200, and the raw material gas, the carrier gas and the like are formed while rotating the film-forming target substrate 100. Flush into room 1010. As a result, a film can be formed on the film-forming target substrate 100.

Further, taking a method for manufacturing a silicon carbide polycrystalline substrate as an example as a method for manufacturing a substrate, such a manufacturing method further includes an exposure step and a combustion removal step described below.

<Exposure process>
As an example of the exposure process, the carbon carbide support substrate obtained by the above-mentioned film forming method and having the silicon carbide polycrystal film formed on the surface is supported by removing the end portion of the formed silicon carbide polycrystal film. The process of exposing the substrate can be mentioned. By this step, the carbon support substrate is exposed, and it becomes easy to vaporize the carbon support substrate by the combustion removal step described later.

A silicon carbide polycrystal film is formed on the side wall of the carbon support substrate by the film forming process. The end face of the carbon support substrate can be exposed by grinding by 4 mm. If the outer peripheral portion of the carbon support substrate is masked with ring-shaped graphite or the like before the formation of the silicon carbide polycrystalline film, end face processing is not required. In this case, the mask can be removed. It is an exposure process.

Alternatively, the carbon support substrate can be exposed on the outer periphery of the side surface by hollowing out a carbon support substrate having a silicon carbide polycrystalline film formed on the surface thereof with a core drill or the like so as to have a desired diameter (for example, 6 inch diameter). can.

<Combustion removal process>
As an example of the combustion removal step, there is a step of holding the carbon support substrate after the exposure step for 100 hours or more under the conditions of a pressure of 1 atm and a temperature of 800 ° C. in the atmosphere. Since the carbon support substrate can be burned and removed by this step, a silicon carbide polycrystalline substrate can be obtained.

(Polishing process)
The method for producing a silicon carbide polycrystalline substrate may include a polishing step of polishing the surface of the formed silicon carbide polycrystalline film after the combustion removal step. If the silicon carbide polycrystalline substrate is used as a substrate for semiconductor manufacturing, surface accuracy that can be used in the semiconductor manufacturing process is required. Therefore, it is preferable to smooth the surface of the silicon carbide substrate by this step.

For example, the surface of the silicon carbide substrate is smoothed through a step of wrapping the silicon carbide substrate with a diamond slurry, hard polishing with a mixed slurry of diamond and alumina, and then polishing with a silica slurry (coloidal silica, pH 11). can do.

(Other processes)
In the above-mentioned manufacturing method, other steps may be included in addition to the above-mentioned steps. For example, a cleaning step for removing deposits on the silicon carbide substrate by the polishing step can be mentioned. Further, the method for manufacturing a substrate of the present invention may include an arbitrary step for manufacturing a substrate in the case of manufacturing a substrate different from the silicon carbide polycrystalline substrate.

In the film forming apparatus of the present embodiment, even if the first gear and the second gear that mesh with each other are made of graphite, the strength of the first gear and the second gear is high, so that the film forming target substrate is rotated. It is possible to suppress damage during film formation of the rotating member (rotating shaft and rotating driving means) to be used repeatedly. Therefore, by reducing the component cost of the film forming apparatus, the manufacturing cost of the substrate can be suppressed.

The present invention is not limited to the above-described embodiment, but includes other configurations and the like that can achieve the object of the present invention, and the present invention also includes modifications and the like of the above-mentioned embodiment.

In addition, the best configuration, method, etc. for carrying out the present invention are disclosed in the above description, but the present invention is not limited thereto. That is, although the present invention has been particularly described mainly with respect to a specific embodiment, the shape, material, quantity, and the like, without departing from the scope of the technical idea and purpose of the present invention, as compared with the above-described embodiments. In other detailed configurations, those skilled in the art can make various modifications. Therefore, the description limiting the shape, material, etc. disclosed above is merely an example for facilitating the understanding of the present invention, and does not limit the present invention. Therefore, those shapes, materials, etc. The description by the name of the member excluding a part or all of the limitation such as is included in the present invention.

Hereinafter, examples of the present invention will be specifically described with reference to comparative examples. Here, a carbon support substrate was used as the film-forming target substrate, and a silicon carbide polycrystalline film was formed on the carbon support substrate. The present invention is not limited to these examples.

(Example 1)
As the film forming apparatus 1000 used for forming the silicon carbide polycrystalline film, a hot wall type thermal CVD apparatus was used in which the raw material gas was introduced from the bottom surface of the film forming chamber 1010 and discharged from the ceiling. Further, as described in the above-described embodiment, the first silicon carbide layer (thickness 500 μm) and the second silicon carbide layer (thickness 500 μm) are formed on the first gear 200a and the second gear 520a. The rotary drive means used is used. As the film-forming target substrate 100, a carbon support substrate having a wafer shape with a thickness of 5 mm and a diameter of 400 mm and an opening 110 having a diameter of 50 mm at the center was used. As shown in FIGS. 2 and 5, the film forming target substrate 100 is placed in the film forming chamber 1010 so that its surface normal line 300 is parallel to the rotation axis 200 and is orthogonal to the flow direction of the raw material gas. Placed in. The number of the film-forming target substrates 100 used for film formation is 6, and the film-forming target surfaces 120 facing each other are skewered on the rotating shaft 200 so that the distance between the substrates is 20 mm. Fixed. The distance between the inner wall of the film forming chamber 1010 and the film forming target surface 120 facing the inner wall is also 20 mm so that the flow of the raw material gas passing between the film forming target substrates 100 becomes uniform. installed.

After the inside of the film forming chamber 1010 is evacuated by an exhaust pump to reduce the pressure, Ar gas is introduced to return the pressure in the film forming chamber 1010 to atmospheric pressure, and the Ar gas is allowed to flow in the film forming chamber 1010. The inside was heated to 1400 ° C. SiCl ₄ and CH ₄ were used as the raw material gas, and H ₂ was used as the carrier gas. The front surface of the film-forming target surface 120 is under the condition that the gas flow rate ratio is SiCl ₄ : CH ₄ : H ₂ = 1: 1:10 while rotating the film-forming target substrate 100 at a rotation speed of 1 rpm. Film formation was carried out for 2.5 hours on the surface 120a and the back surface 120b. At this time, the pressure in the film forming chamber 1010 was controlled to be 20 kPa.

After the film forming step was completed, four substrates having a diameter of 150 mm were hollowed out from one film-forming target substrate 100 using a core drill having an inner diameter of 151 mm for the film-forming target substrate 100 on which the silicon carbide polycrystalline film was formed. The outer peripheral portion of each hollowed-out substrate is in a state where the carbon support substrate, which is the film-forming target substrate 100, is exposed. By heating this substrate in an atmospheric atmosphere at 800 ° C. for 100 hours or more, the carbon support substrate was burnt off, and a total of eight silicon carbide polycrystalline substrates were separated per 100 film-forming target substrates. The film-forming target substrate 100 on which the remaining 5 silicon carbide polycrystalline films were formed was also treated by the same exposure step and combustion removal step to obtain a total of 48 silicon carbide polycrystalline substrates per batch. rice field.

The manufacturing process was repeated 30 times by repeatedly using the same shaft 520 and the rotating shaft 200 with the above manufacturing process as one time. A new shaft and a rotating shaft were used in the first manufacturing process. As a result, the gears of the shaft and the rotating shaft were not damaged or damaged, and when visually confirmed, they were in a state where they could be further used for manufacturing. Moreover, when the thickness of the obtained silicon carbide polycrystalline substrate was confirmed, the thinnest part was 130 μm and the thickest part was 400 μm. Further, when the substrate was visually confirmed, it was found that a good substrate was obtained without any abnormalities that would cause a problem in the subsequent process.

(Comparative Example 1)
In the film forming apparatus, the same as in the above-described first embodiment except that the rotation driving means in which the first silicon carbide layer and the second silicon carbide layer are not formed is used for the first gear and the second gear. A silicon carbide polycrystalline substrate was manufactured.

That is, in the film forming apparatus of Comparative Example 1, the gear shown in FIG. 9 was used. The gear shown in FIG. 9 is a shaft 720 having a rotary shaft having a first gear 600a that receives power transmitted from a rotary drive means (shaft 720) and a second gear 720a that meshes with the first gear 600a to transmit power. And have. The first gear 600a has a tooth portion 601 and the second gear 720a has a tooth portion 721, and the silicon carbide layer is not formed on the surfaces of the tooth portions 601 and 721. By engaging the tooth portion 600 of the first gear 600a and the tooth portion 721 of the second gear 720a, the rotation of the shaft 720 (arrow E) can be converted into the rotation of the rotation shaft (arrow F).

When the manufacturing process was repeated using such a film forming apparatus, the rotation stopped at the 24th manufacturing. When the inside of the film forming apparatus was checked after the film forming process where the rotation stopped, the second gear was damaged, which made it impossible to transmit the rotation of the motor to the rotating shaft, and the rotation of the rotating shaft stopped. I understood. Moreover, when the thickness of the obtained silicon carbide polycrystalline substrate was confirmed, the thinnest part was 100 μm and the thickest part was 460 μm, and it was found that the obtained substrate had a bias in film formation.

(summary)
From the result of Example 1 using the film forming apparatus 1000 which is an exemplary embodiment of the present invention, the strength of the first gear and the second gear that mesh with each other by forming the silicon carbide layer on the first gear and the second gear. It was shown that the member constituting the rotation driving means for rotating the film-forming target substrate can be suppressed from being damaged during film formation and can be used repeatedly until an appropriate replacement time. Further, by forming a film while rotating the film-forming target substrate using such a rotation driving means, it is possible to suppress the unevenness of the film formation of the silicon carbide polycrystalline film and suppress the variation in the film thickness within the same plane. It was shown that the productivity can be improved and the manufacturing cost can be reduced.

1000, 1001 Film forming equipment 1010 Film forming chamber 1020 Introducing port 1030 Exhaust port 1040 Gas introduction chamber 1050 Box 1060 Heater 1100 Housing 200 Rotating shaft 200a, 200b 1st gear 201 Tooth part 202 Tooth root 203 Tooth bottom part 201a 1st silicon carbide Layer 203a Second silicon carbide layer 500 Motor 520 Shaft 530 Gearbox 520a, 520b Second gear 521 Tooth portion 522 Tooth root 523 Tooth bottom portion 521a First silicon carbide layer 523a Second silicon carbide layer 100 Substrate to be deposited

Claims (5)

A film forming chamber for forming a film on the substrate to be deposited by the chemical vapor deposition method,
A raw material gas inlet for introducing the raw material gas into the film forming chamber and
The raw material gas discharge port that discharges the raw material gas from the film forming chamber and
A rotation axis that rotatably holds the film-forming target substrate, and
A rotary drive means for rotating the rotary shaft is provided.
The rotary shaft has a first gear that receives power transmitted from the rotary drive means.
The rotary drive means has a second gear that meshes with the first gear to transmit power.
The first gear and the second gear each have a tooth portion provided side by side in an annular shape and a tooth bottom portion connecting between the tooth roots of the tooth portion.
A film forming apparatus in which the tooth portion of the first gear and the second gear has a first silicon carbide layer formed on the surface of the tooth portion, respectively. The first aspect of claim 1, wherein each of the tooth bottom portions has a second silicon carbide layer formed on the surface of the tooth bottom portion, and the first silicon carbide layer and the second silicon carbide layer are integrated. Film forming equipment. The film forming apparatus according to claim 1 or 2, wherein the thickness of the first silicon carbide layer is 200 μm to 1000 μm. The film forming apparatus according to any one of claims 1 to 3, wherein the rotary shaft and the rotary drive means are made of graphite. The rotation axis is arranged between the raw material gas introduction port and the raw material gas discharge port in the chamber of the film forming chamber so that the longitudinal direction is orthogonal to the flow direction of the raw material gas, and the raw material gas is arranged. It rotates in the flow direction and holds the film-forming target substrate so as to be rotatable in the direction in which the raw material gas flows and the film-forming target surface of the film-forming target substrate is parallel to the flow direction of the raw material gas. , The film forming apparatus according to any one of claims 1 to 4.

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