JP2020066763A - Substrate holding mechanism, deposition device and deposition method for polycrystalline film - Google Patents

Abstract

To provide a deposition method for a polycrystalline film that can prevent fixation of a base material and a holding tool or the like due to deposition of the polycrystalline film, and can realize an industrially high level of yield.SOLUTION: A substrate holding mechanism has a holding part that holds a substrate, a cover that covers the holding part and a part of the substrate held by the holding part, and a nozzle that introduces gas into the cover.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a substrate holding mechanism, a film forming apparatus, and a polycrystalline film forming method.

  Silicon carbide used as a material for the polycrystalline film is a compound semiconductor material composed of silicon and carbon. The dielectric breakdown electric field strength is 10 times that of silicon and the band gap is 3 times that of silicon, and it is possible to control the p-type and n-type required for device fabrication in a wide range. , Is expected as a material for power devices that exceeds the limit of silicon.

  Further, since silicon carbide can obtain a high withstand voltage even with a thinner thickness, it is characterized by a thin structure to obtain a semiconductor with low ON resistance and low loss.

  However, since a silicon carbide semiconductor cannot obtain a large-area wafer and its manufacturing process is complicated as compared with a widely spread Si semiconductor, it cannot be mass-produced and is expensive as compared with a Si semiconductor. .

  Therefore, various measures have been taken to reduce the cost of the silicon carbide semiconductor. For example, Patent Document 1 discloses a method for manufacturing a silicon carbide substrate obtained by bonding a single crystal silicon carbide substrate and a polycrystalline silicon carbide substrate. In this method, hydrogen ion implantation is performed to bond a single crystal silicon carbide substrate on which a thin hydrogen ion implantation layer is formed with a polycrystalline silicon carbide substrate, and then the bonded substrates are heated to perform hydrogen ion implantation. The single crystal silicon carbide substrate is separated in layers.

Japanese Patent Laid-Open No. 2009-117533

  In the silicon carbide substrate obtained by the method described in Patent Document 1, the single crystal silicon carbide substrate is a thin film, and most of the thickness is a polycrystalline silicon carbide substrate. This is because a polycrystalline silicon carbide substrate having a sufficient thickness is used so as to have mechanical strength so that the silicon carbide substrate will not be damaged during handling such as polishing. Therefore, as the thickness of the substrate of polycrystalline silicon carbide, a thickness thicker than the thickness necessary for functioning as a semiconductor is used.

  In addition, conventionally, this polycrystalline film substrate has been obtained by forming a polycrystalline film to a predetermined thickness by a vapor phase growth method such as a CVD method (chemical vapor deposition method). However, the film formation rate in the vapor phase growth method is several to several tens of μm per hour, and a film formation time of several tens of hours is required to obtain a polycrystalline film substrate having mechanical strength. , There is a problem in productivity.

Further, when a polycrystalline silicon carbide substrate is produced by a CVD method, it is generally produced by a thermal CVD method. At this time, the inside of the furnace is set to a thermal environment of 1300 ° C. or higher, and Si system such as SiH _{4 is used.} A raw material gas, a C-based raw material gas such as CH ₄ , a nitrogen gas that is an impurity gas, and a hydrogen gas that is a carrier gas are introduced, and the polycrystalline silicon carbide is heated on the front surface of the base material substrate by a thermal reaction. A polycrystalline silicon carbide substrate is obtained by depositing on both surfaces.

  Since the polycrystalline silicon carbide substrate is used by laminating single crystal silicon carbide which is a semiconductor, it is required that there is no metal contamination. For the above reason, a high-purity carbon material or the like is used as the material that holds the base material as a material that does not cause metal contamination and can withstand a high temperature environment.

  However, although the carbon material can withstand high temperatures, its mechanical strength is weak and it is difficult to have springiness. Therefore, when fixing the Si substrate or the carbon substrate, which is the base material to be deposited, with the carbon material, A method is used in which a base material is sandwiched and fixed by a jig such as a nut made of carbon material or a pressing plate. In this state, when a film of polycrystalline silicon carbide or the like is formed and silicon carbide or the like is deposited, silicon carbide or the like is deposited on the jig made of carbon as well as the Si substrate or the carbon substrate which is the base material, and the treatment is performed. The tool and the base material are fixed to each other by silicon carbide or the like.

  When the jig or the like and the base material are fixed to each other in this way, the jig or the like and the polycrystalline film are contracted by the shrinkage of the polycrystalline film that occurs when the base material is cooled from the high temperature environment after the formation of the polycrystalline film. Due to the stress generated during the process, the polycrystalline film or the base material may be destroyed.

  Also, regarding the base material that does not cause cracking of the polycrystalline film due to stress, etc., when removing the part fixed to the jig, it is necessary to remove it from the base material by cutting the fixed part such as the jig. In this cutting process, the polycrystalline film and the base material may be destroyed and the polycrystalline film may not be recovered.

  As described above, in the method of manufacturing a polycrystalline silicon carbide substrate or the like by forming a thick film on the Si substrate or the carbon substrate by the CVD film forming method, the substrate holding jig or the like and the Si substrate or the carbon substrate are When polycrystalline silicon carbide or the like is deposited on the connecting portion, a stress may be generated due to the adhesion between the substrate holding jig and the substrate, and the stress may cause a problem such as cracking of the formed substrate. . Even if the substrate is not cracked due to stress, the substrate and the polycrystalline film may be destroyed when the substrate is removed from the jig or the like after the polycrystalline film is formed. Due to the destruction of the substrate and the polycrystalline film, the yield of the substrate and the polycrystalline film is remarkably reduced, which greatly increases the cost of film formation. Therefore, it is strongly desired to solve the problem of sticking in manufacturing a polycrystalline silicon carbide substrate or the like.

  In view of the above problems, in the present invention, it is possible to prevent sticking of the base material and the holding jig and the like due to the formation of the polycrystalline film, it is possible to realize a high-yield film formation industrially, It is an object to provide a method for forming a polycrystalline film and the like.

  The inventors of the present invention have conducted extensive studies on a method of fixing a jig or the like to a base material without fixing them when forming a thick film on the base material by a thermal CVD method or the like. . As a result, a cover is provided to prevent the polycrystalline film from forming and sticking to the holding part that holds the substrate, which is the base material of the holding jig, and further, the inside of the cover is inactive while the polycrystalline film is being formed. By flowing the gas, it is possible to prevent a polycrystalline film from being formed on the holding portion for holding the substrate by the holding jig or the like, and the polycrystalline film having a predetermined thickness can be formed without sticking the holding portion. It was found that a film can be formed.

  That is, in order to solve the above problems, the substrate holding mechanism of the present invention includes a holding unit that holds a substrate, a cover that covers a part of the holding unit and the substrate held by the holding unit, and the inside of the cover. And a nozzle for introducing gas into.

  The holding unit has an annular mounting unit for mounting the substrate, the substrate holding mechanism includes a cylindrical rod having the holding unit, the inner diameter of the nozzle and the cross-sectional diameter of the rod is substantially It is the same, the outer diameter of the mounting portion is within 3 times the diameter of the cross section of the rod, the inner dimension width of the cover in the outer diameter direction of the mounting portion, the outer diameter of the mounting portion It may be within 1.5 times.

  In addition, in order to solve the above problems, a film forming apparatus of the present invention includes the above substrate holding mechanism.

  Further, in order to solve the above problems, a method for forming a polycrystalline film of the present invention is a method for forming a polycrystalline film on a substrate using the above film forming apparatus, wherein A holding step of holding the substrate, a film forming step of forming the polycrystalline film on the substrate by chemical vapor deposition after the holding step, and an inert gas introduction for introducing an inert gas into the cover from the nozzle. And a step.

  The flow rate of the inert gas may be equal to or higher than the flow rate of the mixed gas of the raw material gas of the polycrystalline film and the carrier gas.

  The flow rate of the inert gas may be 0.5 m / s to 1.0 m / s.

  The substrate may be a Si substrate or a carbon substrate.

  The polycrystalline film may be a film of silicon carbide, titanium nitride, aluminum nitride, titanium carbide or diamond-like carbon.

  According to the present invention, when a polycrystalline film is formed, a holding jig or the like is provided with a cover at a holding portion for holding a substrate serving as a base material, and an inert gas is introduced into the inside of the cover. It is possible to prevent the substrate and the holding jig and the like from being fixed due to the film formation. As a result, it is possible to realize a film forming method with a high yield industrially, and when forming a polycrystalline film such as a silicon carbide film, its quality and yield can be favorably influenced.

It is a schematic diagram showing an example of a substrate holding mechanism of the present invention. It is a schematic diagram showing an example of the substrate holding mechanism of the present invention different from Drawing 1. It is the schematic which shows an example of the holding | maintenance part of this invention different from FIG. It is a schematic sectional drawing of the film-forming apparatus provided with the substrate holding mechanism of FIG.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

[Substrate holding mechanism]
The substrate holding mechanism of the present invention includes a holding portion, a cover, and a nozzle. By providing these configurations, it is possible to prevent the substrate and the holding portion from sticking to each other. FIG. 1 shows a schematic view of an example of the substrate holding mechanism of the present invention. FIG. 1A is a side view of the substrate holding mechanism 100, which includes a substrate holder 10, a cover 20, and a nozzle 30. FIG. 1B is a sectional view of a part of the substrate holding mechanism 100 cut so that the inside of the cover 20 can be seen. FIG. 1C is a sectional view taken along the line AA of FIG. In addition, FIG. 1D is a cross-sectional view of the holding unit 40 and the substrate 200 after the polycrystalline film 300 is formed by chemical vapor deposition without using the cover 20 and the nozzle 30.

(Substrate holder)
The substrate holder 10 is provided with a holding part 40 described later, holds the substrate 200 as a base material by the holding part 40, and is installed in a chamber of a film forming apparatus into which a raw material gas or a carrier gas is introduced. Is. The substrate holder 10 includes two columns 11 parallel to the vertical direction. The two pillars 11 may be connected at the upper part and the lower part.

<Holding part>
The holding unit 40 included in the substrate holder 10 holds the substrate serving as a base material, and is covered by the cover 20. For example, the holding portion 40 is provided on the pillar 11 of the substrate holder 10, and a pair of washers including an upper washer 41a and a lower washer 41b so that the substrate 200 having a size of 0.3 mm to 5 mm can be gripped and fastened from above and below. 41, and a pair of nuts 42 that are located above the upper washer 41a and below the lower washer 41b and that adjust the fastening state of the substrate 200 by the washer 41, that is, the upper nut 42a and the lower nut 42b. is doing. These washers 41 and nuts 42 serve as holding portions 40, and hold the substrate 200 from above and below. One column 11 can be provided with a plurality of holding parts 40, whereby a plurality of substrates 200 can be gripped. Further, the pillar 11, the washer 41, and the nut 42 may be those having heat resistance to a temperature of about 1300 ° C. to 1600 ° C., which is stable under the condition of forming a polycrystalline film by chemical vapor deposition. Specifically, carbon, silicon carbide, or a composite material obtained by processing these composite materials can be used.

  The substrate holder 10 is arranged so that the two columns 11 are located on the center line of the substrate 200, and holds the substrate 200 at two places (FIG. 1 (c)). Note that the substrate 200 is not limited to being gripped at two places, and columns 11 may be added to grip the substrate at three or four positions, or at five or more positions.

  As shown in FIG. 1D, when a polycrystalline film is formed by chemical vapor deposition by introducing a raw material gas or a carrier gas while holding the substrate 200 from above and below by a holding unit 40, the surface of the substrate 200 Not only that, the polycrystalline film 300 of about 0.3 mm to 3 mm is formed as a continuous film on the surfaces of the holding portion 40 and the pillar 11. Therefore, the substrate 200 and the holding unit 40 are fixed to each other by the polycrystalline film 300. For example, the polycrystalline film 300 and the substrate 200 may be destroyed by the stress between the holding portion 40 and the polycrystalline film 300 due to the shrinkage of the polycrystalline film 300 due to cooling. Further, in order to remove the substrate 200 from the holding portion 40 after fixing, the washer 41 and the nut 42 of the holding portion 40 are to be broken. However, by providing the cover 20 and the nozzle 30 described below, these problems can be solved.

<cover>
The cover 20 covers the holder 40 and a part of the substrate 200 held by the holder 40. If the entire substrate 200 is covered with the cover 20, a polycrystalline film cannot be formed on the substrate 200. Therefore, only the periphery of the holding unit 40 is covered with the cover 20, and the substrate 200 is exposed to the outside of the cover 20. It is preferable that the slit 21 of FIG. Further, an opening portion 23 is provided so that the gas introduced from the nozzle 30 can be introduced into the inside 22. For example, the cover 20 can take the form of a box having a U-shaped cross section.

  As the cover 20, for example, a cover that is stable under the condition of forming a polycrystalline film by chemical vapor deposition and has heat resistance to a temperature of about 1300 ° C. to 1600 ° C. can be used. A carbon material, a silicon carbide material, or a composite material of these materials processed into a box shape can be used.

<nozzle>
The nozzle 30 introduces gas into the inside 22 of the cover 20. The gas sent from the outside into the inside 31 of the nozzle 30 can be introduced into the inside 22 through the opening 32. For example, since the opening 32 of the nozzle 30 is located closer to the inside 22 than the opening 23 of the cover 20, the gas can be introduced into the inside 22 without waste.

  As the nozzle 30, for example, a nozzle that is stable under the condition of forming a polycrystalline film by chemical vapor deposition and has heat resistance to a temperature of about 1300 ° C. to 1600 ° C. can be used. A carbon material, a silicon carbide material, or a composite material of these materials processed into a tube shape can be used. The cross-sectional shape of the nozzle 30 is not particularly limited and may be circular or polygonal.

  The gas introduced from the nozzle 30 is introduced into the inside 22 of the cover 20 (G1 in FIG. 1 (c)), and when the inside 22 is filled with the gas, the excess gas is discharged from the opening 23 of the cover 20 to the outside of the cover. (Fig. 1 (c) G2).

  The holding part 40 has a lower washer 41b as an annular mounting part on which the substrate 200 is mounted, the substrate holding mechanism 100 has a column 11 as a cylindrical rod having the holding part 40, and has an inner diameter d1 of the nozzle 30. The diameter d2 of the cross section of the rod is substantially the same, the outer diameter d3 of the mounting portion (lower washer 41b) is within three times the diameter d2 of the cross section of the rod, and the outer diameter direction of the mounting portion (lower washer 41b). The horizontal inner dimension width d4 of the cover is within 1.5 times the outer diameter d3 of the mounting portion (lower washer 41b), and the vertical inner dimension width d5 of the cover 20 is the thickness of the holding portion 40. (That is, the total thickness of the upper washer 41a, the lower washer 41b, the upper nut 42a, and the lower nut 42b) is preferably 1.5 times or less. By satisfying these conditions, it is possible to more effectively prevent the substrate 200 and the holding unit 40 from being fixed to each other by the polycrystalline film 300 with a small amount of gas.

  If the inner diameter d1 of the nozzle 30 and the diameter d2 of the cross section of the rod are not substantially the same, it may be difficult to balance the flow rate and the flow rate of the gas passing through the nozzle 30. For example, in the case where the inner diameter d1 of the nozzle is larger than the diameter d2 of the cross section of the rod, in order to maintain the standard flow velocity of 0.5 m / s, the nozzle 30 containing a large amount of inert gas or the like is used. May be required. Further, when the inner diameter d1 of the nozzle is smaller than the diameter d2 of the cross section of the rod, it is easy to maintain the flow velocity at 0.5 m / s, but the amount of the inert gas introduced into the cover 20 is reduced. Then, there is a possibility that the raw material gas may enter the cover 20. In the present invention, the case where the inner diameter d1 is the same as the diameter d2, and the case where the inner diameter d1 is 10% shorter or 10% longer than the diameter d2 are included in substantially the same range.

  When the outer diameter d3 of the mounting portion (lower washer 41b) is larger than three times the diameter d2 of the rod cross section, the gas introduced from the nozzle 30 into the inside 22 of the cover 20 (FIG. 1 (c) G1). However, there may be a problem in the gas flow that is discharged from the opening 23 of the cover 20 to the outside of the cover (G2 in FIG. 1C). In this case, as shown in FIG. Since the continuous polycrystalline film 300 is formed on the surface of the holding unit 40 and the surface of the substrate 200, the holding unit 40 and the substrate 200 may be fixed to each other.

  Further, when the horizontal inner dimension width d4 of the cover in the outer diameter direction of the mounting portion (lower washer 41b) is larger than 1.5 times the outer diameter d3 of the mounting portion (lower washer 41b), When the inner width d5 of the vertical direction 20 is larger than 1.5 times the thickness of the holding portion 40, the gas introduced from the nozzle 30 does not sufficiently hit the holding portion 40, and thus the holding portion 40 When the polycrystalline film 300 is formed on the surface of, the upper washer 41a, the lower washer 41b, the upper nut 42a, and the lower nut 42b may be fixed to each other. Further, since the continuous polycrystalline film 300 is formed on the surface of the holder 40 and the surface of the substrate 200, the holder 40 and the substrate 200 may be fixed to each other.

<Other configurations>
The substrate holding mechanism of the present invention can have other configurations besides the holding portion, the cover and the nozzle. For example, in addition to the substrate holder 10 described above, a fixing member for fixing the substrate holder 10, the cover 20, the nozzle 30 and the like can be provided.

  FIG. 2 is a schematic view showing an example of the substrate holding mechanism of the present invention different from FIG. According to the present invention, the substrate 200 can be held in one place by one holding unit 40 like the substrate holding mechanism 100 in FIG. 1, but the substrate 200 can be held in one place like the substrate holding mechanism 110 in FIG. The two holding portions 40 may hold two places (FIGS. 2A and 2B). Further, the cover 20, the nozzle 30, and the like can be increased together with the holding portion 40. In the present invention, the substrate 200 can be held at three or more places.

  The schematic view of FIG. 3 shows an example of the holding portion of the present invention different from that of FIG. In the present invention, instead of the holding unit 40 shown in FIG. 1, the pillar 11 may have the placing unit 45, which is projected in the shape of, for example, a claw, as a holding unit so that the substrate 200 can be placed (FIG. 3 (a)). One column 11 can be provided with a plurality of mounting portions 45, and thus the substrate holder 10 can hold a plurality of substrates 200.

  As the mounting portion 45, for example, one having heat resistance to a temperature of about 1300 ° C. to 1600 ° C., which is stable under the condition of forming a polycrystalline film by chemical vapor deposition, can be used. Can be made of carbon, silicon carbide, or a composite material obtained by processing these composite materials.

  Similar to FIG. 1C, FIG. 3B is a sectional view taken along line AA of the substrate holding mechanism 100. The substrate holder 10 is arranged so that the two columns 11 are located on the center line of the substrate 200, and holds the substrate 200 at two places (FIG. 3 (b)). Note that the substrate 200 is not limited to being held at two places, and columns 11 may be added to hold the substrate 200 at three places, four places, or five or more places.

[Film forming equipment]
A film forming apparatus of the present invention includes the substrate holding mechanism of the present invention described above. By using this film forming apparatus, it is possible to form a polycrystalline film while preventing the substrate serving as the base material and the holding portion from being fixed to each other.

  FIG. 4 shows a schematic cross-sectional view of a film forming apparatus 1000 including the substrate holding mechanism 100 of FIG. The substrate holding mechanism 100 may include the holding unit 40 or the mounting unit 45. Further, the film forming apparatus 1000 of the present invention can have other configurations in addition to the substrate holding mechanism 100. For example, a film formation chamber 1010 for forming the polycrystalline film 300 on the substrate 200, an inlet 1020 for introducing a source gas or a carrier gas into the film formation chamber 1010, a source gas or a carrier gas discharged from the film formation chamber 1010 are formed. An exhaust port 1030 for exhausting the film device 1000 to the outside, an exhaust gas introducing chamber 1040 for introducing the source gas and the carrier gas exhausted from the film forming chamber 1010 to the exhaust port 1030, a box 1050 for covering the exhaust gas introducing chamber, and a box 1050. A heater 1060 that controls the temperature in the film formation chamber 1010 from the outside, and a water-cooled stainless steel casing 1100 that is outside the heater 1060 and is an exterior of the film formation apparatus 1000 can be provided.

[Method for forming polycrystalline film]
The method for forming a polycrystalline film according to the present invention is a method for forming a polycrystalline film 300 on a substrate 200 using the above-described film forming apparatus 1000 according to the present invention. And an active gas introducing step.

(substrate)
The substrate 200 (base material) on which the polycrystalline film 300 is formed is not particularly limited, and examples thereof include a Si substrate and a carbon substrate.

(Polycrystalline film)
The polycrystalline film 300 formed on the substrate 200 is not particularly limited, but may be, for example, a film of silicon carbide, titanium nitride, aluminum nitride, titanium carbide, or diamond-like carbon.

<Holding process>
The holding step is a step of holding the substrate 200 in the holding section. When the holding unit 40 is used as the holding unit, a step of holding the substrate 200 from above and below with the washer 41 and the nut 42 can be mentioned. Moreover, when using the mounting part 45 as a holding part, the process of mounting the board | substrate 200 on the mounting part 45 is mentioned.

<Film forming process>
The film forming step is a step of forming the polycrystalline film 300 on the substrate 200 by chemical vapor deposition after the holding step. As a specific example of chemical vapor deposition, a source gas containing a component of the polycrystalline film 300, a carrier gas, or the like is supplied onto a heated substrate 200, and the polycrystalline film is formed by a chemical reaction on the surface of the substrate 200 or in a gas phase. The method of depositing is mentioned.

(Raw material gas)
There is no particular limitation as long as the polycrystalline film 300 can be formed, and a commonly used source gas can be used. For example, when forming a polycrystalline film of silicon carbide, SiCl ₄ gas, SiCl ₃ CH ₃ gas, CH ₄ gas, C ₃ H ₈ gas or the like can be used. When forming the titanium nitride polycrystalline film 300, TiCl ₄ gas, N ₂ gas, or the like can be used. When forming the polycrystalline film 300 of aluminum nitride, AlCl ₃ gas, NH ₃ gas, or the like can be used. When forming the titanium carbide polycrystalline film 300, TiCl ₄ gas, CH ₄ gas, or the like can be used. When forming the polycrystalline film 300 of diamond-like carbon, a hydrocarbon gas such as acetylene can be used.

(Carrier gas)
If the source gas can be spread on the substrate without disturbing the formation of the polycrystalline film 300, a commonly used carrier gas can be used. For example, H ₂ gas or the like can be used as a carrier gas.

<Inert gas introduction process>
The inert gas introducing step is a step of introducing an inert gas into the inside 22 of the cover 20 from the nozzle 30. In this step, since the inside of the cover 20 is filled with the inert gas and the polycrystalline film 300 cannot be formed on the substrate 200, the substrate 200 and the holding portion 40 (or the mounting portion 45) are not formed into the polycrystalline film. It is possible to prevent sticking by 300.

  It is preferable that the inert gas introduction step be started after the holding step and before the film forming step and ended after the film forming step. That is, since the inert gas is introduced into the inside 22 of the cover 20 during the film forming process, the above-mentioned fixation can be effectively prevented. Note that, provided that the substrate 200 is not fixed by the polycrystalline film 300, the inert gas introducing step can be started during the film forming step, and the inert gas introducing step can be performed during the film forming step. It is possible to end.

(Inert gas)
The inert gas to be introduced is not particularly limited as long as it is a gas that can prevent the polycrystalline film 300 from forming on the substrate 200 in the inside 22 of the cover 20 and can prevent the above-mentioned fixation. For example, a rare gas or a nitrogen gas can be used, it is preferable to use a rare gas having no fear of a dopant, and an inexpensive and general-purpose argon gas can be used.

  The flow rate of the inert gas varies depending on the size and mass of the holding portion and the substrate, but is preferably equal to or higher than the flow rate of the mixed gas of the raw material gas of the polycrystalline film 300 and the carrier gas. This condition makes it easier to prevent the polycrystalline film 300 from being formed on the substrate 200 in the inside 22 of the cover 20.

  Specifically, the flow rate of the inert gas is preferably 0.5 m / s to 1.0 m / s. This condition effectively prevents the polycrystalline film 300 from being formed on the substrate 200 in the inside 22 of the cover 20 even when the sizes of the substrate 200 and the cover 20 are different. be able to. If the flow rate of the inert gas is less than 0.5 m / s, the polycrystalline film 300 may be formed in the inside 22 as well. If the flow rate of the inert gas is higher than 1.0 m / s, the inert gas may affect the formation of the polycrystalline film 300 on the substrate 200 outside the cover 20.

<Other processes>
The film forming method of the present invention can include other steps in addition to the holding step, the film forming step, and the inert gas introducing step. For example, in a heating step of heating the substrate to a predetermined temperature between the holding step and the film forming step, or in a substrate before chemical vapor deposition, the substrate is placed in an inert atmosphere so as not to cause any reaction that inhibits the film formation. Therefore, a step of circulating an inert gas such as a rare gas or nitrogen gas may be used.

  Hereinafter, the present invention will be described more specifically based on Examples. However, the present invention is not limited to the contents of the following examples.

(Example 1)
The film forming apparatus 1000 shown in FIG. 4 including the substrate holder 10, the cover 20, the nozzle 30, and the substrate holding mechanism 100 including the holding unit 40 shown in FIG. 1A was used. The substrate 200 (carbon substrate having a thickness of 4 inches and a thickness of 0.5 mm) is held in the holding unit 40 (holding step), and argon gas is introduced into the inside 22 of the cover 20 from the nozzle 30 at a flow rate of 0.5 m / s ( Inert gas introduction step). Then, a silicon carbide film having a thickness of 0.3 mm was formed as the polycrystalline film 300 on both the front surface and the back surface of the substrate 200 outside the cover 20 (film forming step). The film forming conditions were such that the pressure inside the film forming chamber 1010 was 25 kPa, the temperature was 1350 ° C., SiCl ₄ gas and CH ₄ gas were introduced at 800 sccm each as a source gas, and hydrogen gas was introduced at 5000 sccm as a carrier gas for 10 hours. The membrane was carried out. After the film forming process is completed, the inert gas introducing process is completed, and the substrate 200 on which the polycrystalline film 300 is formed is cooled and then taken out from the film forming apparatus 1000 to determine whether or not the substrate 200 and the polycrystalline film 300 are fixed in the holding unit 40. It was confirmed. The results are shown in Table 1.

  Two substrates 200 were held in parallel. As the pillar 11, a carbon rod having a sectional diameter d2 of 5 mm was used. The holding portion 40 was made of carbon, and the washer 41 had an outer diameter of 15 mm. The nozzle 30 is made of carbon, and the inner diameter d1 is set to 6 mm, which is substantially the same as the cross-sectional diameter d2 of the column 11. The cover 20 is made of carbon and has an inner width of 20 mm.

(Example 2)
In the inert gas introducing step, the polycrystalline film 300 was formed on the substrate 200 under the same conditions as in Example 1 except that the flow rate of the argon gas was 1.0 m / s.

(Comparative Example 1)
A polycrystalline film 300 was formed on the substrate 200 under the same conditions as in Example 1 except that argon gas was not introduced into the inside 22 of the cover 20.

(Comparative example 2)
The polycrystalline film 300 was formed on the substrate 200 under the same conditions as in Example 1 except that the substrate holding mechanism 100 having no cover 20 was used.

(result)
In the first and second embodiments, the inert gas introduction step of using the substrate holding mechanism 100 including the cover 20 and introducing the argon gas into the inside 22 of the cover 20 under the condition of 0.5 m / s to 1.0 m / s. By doing so, it was possible to prevent the raw material gas and the carrier gas from entering the inside 22 of the cover 20. As a result, the polycrystalline film 300 is uniformly formed on the substrate 200 outside the cover 20, and on the other hand, inside the cover 20, the polycrystalline film 300 as shown in FIG. Adhesion between the substrate 200 and the holding unit 40 was not recognized, and the substrate 200 could be removed from the holding unit 40 without difficulty.

  On the other hand, in Comparative Example 1, as a result of not performing the inert gas introduction step, the raw material gas penetrated into the inside 22 of the cover 20, and the adhesion between the substrate 200 and the holding portion 40 due to the polycrystalline film 300 was confirmed. As a result, when the substrate 200 was removed from the holder 40, the substrate 200 and the polycrystalline film 300 were partially destroyed.

  Further, in Comparative Example 2, since the substrate holding mechanism 100 without the cover 20 is used, even if an inert gas is introduced from the nozzle 30, the effect is not obtained, and the substrate 200 held by the polycrystalline film 300 is held. Adhesion to the part 40 was recognized. As a result, when the substrate 200 was removed from the holder 40, the substrate 200 and the polycrystalline film 300 were partially destroyed. It should be noted that no film formation defect of the polycrystalline film 300 on the substrate 200 due to the introduction of the inert gas into the film formation chamber 1010 was observed.

[Summary]
From the results of the above examples, according to the present invention, it is possible to prevent the adhesion between the substrate and the holding portion, which had occurred when the silicon carbide film was formed on the carbon substrate, and as a result, the stress of the polycrystalline film was reduced. It is clear that the effect of suppressing the damage of the substrate due to the adhesion and the sticking was obtained. In the examples, as an example, the case where a polycrystalline silicon carbide film is formed on a carbon substrate has been introduced. However, the effect of the present invention is not limited to this case, but is not limited to the case of a carbon substrate or a Si substrate. It is also obtained when a polycrystalline film of titanium nitride, aluminum nitride, titanium carbide, diamond-like carbon or the like is formed.

10 substrate holder 11 pillar 20 cover 21 slit 22 inside 23 opening 30 nozzle 31 inside 32 opening 40 holding part 41 washer 41a upper washer 41b lower washer 42 nut 42a upper nut 42b lower nut 45 mounting part 100 substrate holding mechanism 110 substrate Holding mechanism 200 Substrate 300 Polycrystalline film 1000 Film forming apparatus 1010 Film forming chamber 1020 Inlet port 1030 Exhaust port 1040 Exhaust gas introducing chamber 1050 Box 1060 Heater 1100 Housing d1 Nozzle inner diameter d2 Column cross-section diameter d3 Bottom washer outer diameter d4 Horizontal inner width of the cover d5 Vertical inner width of the cover G1 arrow G2 arrow

Claims (8)

A holder for holding the substrate,
A cover that covers a part of the holding unit and the substrate held by the holding unit;
And a nozzle for introducing gas into the cover. The holding portion has an annular mounting portion for mounting the substrate,
The substrate holding mechanism includes a cylindrical rod having the holding portion,
The inner diameter of the nozzle and the diameter of the cross section of the rod are substantially the same,
The outer diameter of the mounting portion is within 3 times the diameter of the cross section of the rod,
The substrate holding mechanism according to claim 1, wherein the inner dimension width of the cover in the outer diameter direction of the mounting portion is within 1.5 times the outer diameter of the mounting portion.   A film forming apparatus comprising the substrate holding mechanism according to claim 1. A method for forming a polycrystalline film on a substrate using the film forming apparatus according to claim 3,
A holding step of holding the substrate in the holding part,
A film forming step of forming the polycrystalline film on the substrate by chemical vapor deposition after the holding step,
And a step of introducing an inert gas into the cover from the nozzle, to form a polycrystalline film.   The method for forming a polycrystalline film according to claim 4, wherein the flow rate of the inert gas is equal to or higher than the flow rate of a mixed gas of the raw material gas and the carrier gas of the polycrystalline film.   The method for forming a polycrystalline film according to claim 4, wherein the flow rate of the inert gas is 0.5 m / s to 1.0 m / s.   The method for forming a polycrystalline film according to claim 4, wherein the substrate is a Si substrate or a carbon substrate.   The method for forming a polycrystalline film according to claim 4, wherein the polycrystalline film is a film of silicon carbide, titanium nitride, aluminum nitride, titanium carbide or diamond-like carbon.

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