JP2020161542A - Film-forming apparatus and film-forming method - Google Patents

Abstract

To provide a film-forming apparatus and a film-forming method that are capable of preventing deposition of SiC at gas ejection ports and inside pipes connected to the gas ejection ports to form a film having a uniform composition.SOLUTION: A film-forming apparatus includes: a film-forming chamber having a rectangular parallelepiped internal shape consisting of a first surface, a second surface facing the first surface, and four side surfaces connecting the first surface and the second surface; mixed gas ejection ports that are located through or near the first surface and eject a mixed gas containing a raw material gas and a carrier gas into the film-forming chamber; a mixed gas discharge port that is located through or near the second surface and discharges the mixed gas from the film-forming chamber; a heater that surrounds the four side surfaces and heats the film-forming chamber; a substrate holder which can hold a plurality of substrates while stacking the substrates at equal intervals in a non-contact manner, and in which film-forming target surfaces of the substrates are set in parallel to the side surfaces between the first surface and the second surface of the film-forming chamber; and ejection speed control means capable of making the ejection speed of the mixed gas to be ejected from the mixed gas ejection port faster than diffusion speed of the mixed gas.SELECTED DRAWING: Figure 1

Description

The present invention relates to a film forming apparatus and a film forming method, for example, a film forming apparatus and a film forming apparatus for forming a polycrystalline silicon carbide or the like by laminating a plurality of supporting substrates or the like in a non-contact state at equal intervals with a gap between them. It relates to a film forming method.

Silicon carbide (SiC) is a wide bandgap semiconductor having a wide forbidden bandwidth of 2.2 to 3.3 eV, and due to its excellent physical and chemical properties, for example, high frequency electronic devices, high withstand voltage and high output. Research and development of devices (semiconductor devices) made of silicon carbide, including electronic devices and short-wavelength optical devices from blue to ultraviolet, are being actively carried out. In order to promote the practical use of SiC devices, it is required to manufacture a large-diameter silicon carbide substrate for high-quality SiC epitaxial growth. Currently, most of them are manufactured by a sublimation recrystallization method (called an improved Rayleigh method, an improved Rayleigh method, etc.) or a CVD method (chemical vapor deposition method) using a seed crystal.

The method for producing a silicon carbide substrate using the CVD method is to cause a vapor phase reaction of a raw material gas, deposit a silicon carbide product on the surface of the base material to form a film, and then remove the base material. A high-purity silicon carbide substrate can be obtained. The base material is removed by cutting, polishing, or the like, but if a carbon material is used as the base material, it can be removed by heat treatment in air.

In Patent Document 1, as a method for manufacturing a silicon carbide substrate by a CVD method, a silicon carbide film is formed on the surface of a base material by a chemical vapor deposition method, and then the base material is removed to form both surfaces of the silicon carbide substrate. Further, a method for producing a silicon carbide substrate by a chemical vapor deposition method has been proposed, which comprises forming a silicon carbide film.

When the thermal CVD method is used in the CVD method for manufacturing the SiC substrate, generally, the silicon carbide substrate is placed on the substrate holder in the growth chamber, and the holder is rotated while directly above the SiC substrate. For example, a method is adopted in which a raw material gas obtained by mixing a silicon source silane gas or chlorosilane gas and a carbon source hydrocarbon gas or the like is supplied together with a carrier gas such as hydrogen to epitaxially grow a SiC single crystal thin film (. For example, see Non-Patent Document 1).

At this time, a doping gas such as nitrogen (N ₂ ) is usually mixed with the raw material gas and supplied. The substrate processing apparatus for mounting the SiC substrate on the holder in this way is referred to as a substrate processing apparatus having a horizontal arrangement structure. Further, even in a substrate processing device having the same horizontal arrangement structure, a plurality of silicon carbide substrates are mounted side by side using a larger holder, and each SiC substrate is rotated (rotated) and the holder is rotated (revolved) once. It is also possible to obtain a plurality of epitaxially grown silicon carbide wafers (epitaxial SiC wafers) by the above process. A substrate processing apparatus for arranging a plurality of SiC substrates on a holder in this way is referred to as a substrate processing apparatus having a planetary structure here.

In the case of this planetary structure substrate processing device, it is possible to create an equivalent epitaxial growth environment for a plurality of SiC substrates by combining the rotation and revolution of the SiC substrate, so that the board surface of one SiC substrate can be created. Not only that, it is possible to suppress variations in film thickness and doping density among a plurality of SiC substrates, which is considered to be advantageous from the viewpoint of productivity. However, since the number of SiC boards that can be mounted is determined by the size of the holder, the number of boards that can be mounted decreases as the diameter of the SiC board increases. In particular, in the case of a SiC substrate whose diameter is to be increased, the productivity of the epitaxial SiC wafer must be examined at the same time.

One of the means for improving the productivity of epitaxial SiC wafers is a substrate processing apparatus having a vertical arrangement structure in which holders are arranged in the vertical direction in a growth chamber and a plurality of SiC substrates are arranged in a direction in which they are laminated with a gap between them. Be done. According to this, even if the diameter of the SiC substrate is increased, there are not so many restrictions on the apparatus, and by increasing the number of SiC substrates arranged in the vertical direction, the productivity is improved as compared with the substrate processing apparatus having a horizontal arrangement structure. It makes it possible to manufacture epitaxial SiC wafers.

However, in such a substrate processing apparatus having a vertical arrangement structure, control different from that in the case of a substrate processing apparatus having a horizontal arrangement structure is required. For example, if the temperatures of the growth chambers are not uniform in the vertical direction, the film thickness of the obtained epitaxial growth film may change or the doping density may vary depending on the location where the silicon carbide substrate is placed. Further, in order to uniformly grow the epitaxial growth film on each SiC substrate arranged in the growth chamber in the vertical direction, a raw material gas containing a silicon source and a carbon source is introduced through a pipe along the growth chamber in the vertical direction. , A gas outlet is provided at a position corresponding to each gap between the SiC substrates, and the raw material gas is supplied to the surface of the SiC substrate. Here, when a silicon source gas and a carbon source gas are mixed and supplied as in the case of a substrate processing apparatus having a horizontal arrangement structure, these gases are used in the piping under a high temperature environment in the thermal CVD method of SiC. Reacts to generate SiC, which may block the outlet or cause SiC to accumulate in the pipe.

Therefore, a substrate processing apparatus having a vertical arrangement structure has been proposed in which a silicon material gas containing a silicon source and a carbon material gas containing a carbon source are introduced into a growth chamber by individual gas introduction pipes (for example). See Patent Documents 2 and 3). By using this substrate processing apparatus having a vertical arrangement structure, it is possible to form a SiC epitaxial growth film with a uniform film thickness on a large number of SiC substrates. However, even if such a substrate processing apparatus is used, the obtained epitaxial SiC wafer may have a variation in the doping density of the SiC single crystal thin film depending on the location where the SiC substrate is placed, or the SiC single in a single epitaxial SiC wafer. The doping density in the same plane of the crystal thin film may vary.

In order to deal with these problems, in Patent Document 4, the gas introduction pipe has a gas outlet at a position corresponding to each gap between the silicon carbide single crystal substrates, and the surface of each silicon carbide single crystal substrate is provided. A method for producing an epitaxial silicon carbide wafer has been proposed in which a silicon material gas, a carbon material gas, and a doping gas and a rare gas are mixed and supplied as a carrier gas, respectively.

Japanese Unexamined Patent Publication No. 8-188408 JP-A-2010-283336 Japanese Unexamined Patent Publication No. 2011-3885 Japanese Unexamined Patent Publication No. 2014-103188

Materials Science Forum Vols.45-648 (2010), pp77-82

However, when the substrates are laminated on the conventional hot wall type vertical furnace with the film formation target surface horizontal as in Patent Document 4, SiC is generated in order to supply sufficient raw material gas between the substrates. It is necessary to form the pipe in the temperature region, and if this is done, SiC may be generated and the SiC may be deposited in the pipe or in the gas outlet, which may make it difficult to control the gas supply. In addition, since one or more gas outlets and exhaust ports are required between the laminated substrates, if the number of laminated substrates increases, the number of gas outlets and exhaust ports to be managed increases, and management is difficult. There is. When the raw material gas is separately supplied as the silicon material gas and the carbon material gas, the raw material gas may not be uniformly mixed on the substrate due to insufficient mixing of the raw material gas.

Therefore, in view of the above problems, the present invention is a film forming apparatus and a film forming method capable of forming a film having a uniform composition by preventing SiC from being deposited in the gas outlet and the piping connected thereto. Is to provide.

In order to solve the above problems, the film forming apparatus of the present invention includes a first surface, a second surface facing the first surface, and four side surfaces connecting the first surface and the second surface. A film forming chamber having a rectangular inner shape, a mixed gas outlet which is located on or near the first surface and ejects a mixed gas containing a raw material gas and a carrier gas into the film forming chamber, and the second surface or A mixed gas discharge port that discharges the mixed gas from the film forming chamber, a heater that surrounds the four side surfaces and heats the film forming chamber, and a plurality of substrates in the vicinity thereof, without contacting the substrates. A substrate holder that can be laminated and held at equal intervals and can be installed between the first surface and the second surface of the film forming chamber in parallel with the film forming target surface of the substrate. It is provided with an ejection speed control means capable of making the ejection speed of the mixed gas ejected from the mixed gas ejection port faster than the diffusion speed of the mixed gas.

It is preferable that the plurality of the mixed gas outlets are arranged in the stacking direction of the plurality of substrates.

The shortest distance between the mixed gas outlet and the substrate holder is preferably 150 mm or more.

Further, in order to solve the above-mentioned problems, the film-forming method of the present invention is a film-forming method using the above-mentioned film-forming apparatus of the present invention, and the substrates are not brought into contact with the substrate holder in the film-forming chamber. The mixed gas is ejected from the mixed gas ejection port into the film forming chamber with respect to the plurality of substrates which are laminated at equal intervals and the surface to be formed is installed parallel to the side surface. This includes a film forming step of discharging the mixed gas from the film forming chamber from the mixed gas discharge port and circulating the mixed gas in a direction parallel to the film forming target surface to form a film on the substrate.

The ejection speed of the mixed gas ejected from the mixed gas ejection port may be faster than the diffusion rate of the mixed gas.

A method for forming a silicon carbide polycrystal film, the raw material gas contains a silicon source gas and a carbon source gas, and the silicon source gas is SiH ₄ , SiH ₃ Cl, SiH ₂ Cl ₂ , SiHCl ₃ , and SiCl. One or more selected from the group consisting of ₄ , the carbon source gas is one or more selected from hydrocarbons having 5 or less carbon atoms, and the carrier gas is hydrogen gas. It may be.

The temperature inside the film forming chamber may be 1400K to 1700K, and the temperature of the first surface may be 1100K or less.

The temperature of the mixed gas outlet may be 1200 K or less.

A method for forming a silicon carbide single crystal film, the raw material gas contains a silicon source gas and a carbon source gas, and the silicon source gas is SiH ₄ , SiH ₃ Cl, SiH ₂ Cl ₂ , SiHCl ₃ , and SiCl. One or more selected from the group consisting of ₄ , the carbon source gas is one or more selected from hydrocarbons having 5 or less carbon atoms, and the carrier gas is hydrogen gas. The ratio (C / Si) of the number of carbon atoms in the carbon source gas to the number of silicon atoms in the silicon source gas is set to 0.7 to 1.3, and a thin film of silicon carbide single crystal is epitaxially grown on the substrate. You may.

According to the present invention, it is possible to provide a film forming apparatus and a film forming method capable of preventing SiC from being deposited in a gas outlet and a pipe connected to the gas outlet and forming a film having a uniform composition.

It is the schematic which shows the cross section seen from the upper surface of the film forming apparatus 1000 of one Embodiment of this invention. It is a front schematic view which looked at the 1st surface 110 from the inside of a film forming chamber 110. It is a front schematic view which looked at the 2nd surface 120 from the inside of the film forming chamber 110. It is a schematic diagram of a substrate holder 500. It is a schematic diagram explaining the ejection of a mixed gas. It is the schematic which shows the cross section of the side surface of the film forming apparatus 2000 of the comparative example.

Hereinafter, an embodiment of the film forming apparatus and the film forming method of the present invention will be described with reference to the drawings. However, the present invention is not limited to these embodiments.

[Film formation device 1000]
FIG. 1 shows a schematic view showing a cross section of the film forming apparatus 1000 according to the embodiment of the present invention as viewed from the upper surface. The film forming apparatus 1000 includes a film forming chamber 100, a mixed gas ejection port 200, a mixed gas discharge port 300, a heater 400, and a substrate holder 500.

<Film formation chamber 100>
The film forming chamber 100 has a rectangular parallelepiped internal shape composed of a first surface 110, a second surface 120 facing the first surface 110, and four side surfaces 130 connecting the first surface 110 and the second surface 120. .. By adopting a rectangular parallelepiped inner shape, when a plurality of substrates are installed in the film forming chamber 100, the shapes of the gap between the substrates and the gap between the substrate and the side surface 130 are the same or similar. Therefore, similarly to the mixed gas flowing between the substrates, the mixed gas flowing between the side surface 130 and the substrate can be uniformly flowed from the mixed gas ejection port 200 toward the mixed gas discharge port 300. As a result, a film that is uniform and has little variation can be formed on the substrate.

For example, when the inner shape of the film forming chamber 100 is not a rectangular parallelepiped shape but a tubular shape, the shapes of the gap between the substrate and the substrate and the shape of the gap between the substrate and the side surface 130 are significantly different. The mixed gas flowing between the side surface 130 and the mixed gas flowing between the side surface 130 and the substrate does not flow uniformly. As a result, the film formed between the substrates and the film formed between the substrates and the side surface 130 may become non-uniform, and a film having a large variation between the substrates may be formed.

The inner shape of the film forming chamber 100 may be large enough to accommodate the substrate held in the substrate holder 500 and the substrate holder 500, and the mixed gas not involved in the film formation may be discharged from the mixed gas outlet 200. It is preferable not to provide an extra space for flowing toward 300 and being discharged from the film forming chamber 100.

Further, the film forming chamber 100 is preferably made of graphite. Graphite can be easily processed into a rectangular parallelepiped shape, and can have sufficient durability under high-temperature film-forming conditions by creating an inert atmosphere during film-forming.

<Mixed gas outlet 200>
The mixed gas ejection port 200 is located on or near the first surface 110 of the film forming chamber 100, and ejects a mixed gas containing a raw material gas and a carrier gas into the film forming chamber 100. It is preferable that there are a plurality of mixed gas outlets 200, but there may be one. Since there are a plurality of mixed gas ejection ports 200, the mixed gas can be ejected more uniformly into the film forming chamber 100 as compared with the case where there is only one. As an example of the mixed gas ejection port 200, it corresponds to the opening end portion where the mixed gas is ejected in the mixed gas introduction pipe 210 through which the mixed gas flows. The mixed gas ejection port 200 may be located on the first surface 110, and as shown in FIG. 1, is in the vicinity of the first surface 110, and the gas leakage of the mixed gas or the inside side of the film forming chamber 100 may occur. It may be outside the film forming chamber 100 on the assumption that it does not exist. As a guide, the vicinity is, for example, about 20 mm from the first surface 110 to 20 mm. In addition, a temperature control means such as a heater capable of appropriately heating the mixed gas introduction pipe 210 and a cooler capable of cooling may be provided so that the temperature of the mixed gas ejection port 200 can be controlled.

FIG. 2 shows a schematic front view of the first surface 110 as viewed from the inside of the film forming chamber 110. In FIG. 2, four mixed gas outlets 200 are arranged in a row on the first surface 110. The direction in which the four mixed gas ejection ports 200 are arranged coincides with the direction in which the substrates 600 are arranged side by side in the substrate holder 500. It is possible to evenly discharge the mixed gas from each of the mixed gas outlets 200. The inner diameter of the mixed gas outlet 200 may be optimal depending on the number of mixed gas outlets 200 and the ejection conditions, and is not particularly limited as long as there is no problem in ejecting the mixed gas, but is set in the range of, for example, 10 mm to 25 mm. can do. Further, the distance between the adjacent mixed gas outlets 200 may be optimal depending on the number of the mixed gas outlets 200 and the ejection conditions, and is not particularly limited as long as there is no problem in ejecting the mixed gas 810, but for example, 2 mm. It can be set in the range of ~ 16 mm. Further, the mixed gas ejection port 200 may be arranged on the first surface 110 by a plurality of rows and a plurality of columns.

<Mixed gas discharge port 300>
The mixed gas discharge port 300 is located on or near the second surface 120 of the film forming chamber 100, and discharges the mixed gas from the film forming chamber 100. As an example of the mixed gas discharge port 300, it corresponds to an opening end portion where the mixed gas is discharged in the mixed gas discharge pipe 310 that flows to discharge the mixed gas to the outside. The mixed gas discharge port 300 may be located on the second surface 120, and is in the vicinity of the second surface 120 as shown in FIG. It may be outside the film forming chamber 100 on the assumption that it does not exist. As a guide, the vicinity is, for example, about 20 mm from the second surface 120 to 20 mm. The temperature of a heater that can be appropriately heated, a cooler that can be cooled, or the like in order to control the temperature of the mixed gas discharge port 300 or the mixed gas introduction pipe 210 so that silicon carbide or the like does not precipitate in the mixed gas discharge port 300 or the mixed gas discharge pipe 310. A control means may be provided.

FIG. 3 shows a schematic front view of the second surface 120 as viewed from the inside of the film forming chamber 100. In FIG. 3, one mixed gas discharge port 300 is arranged in the center of the second surface 120. The mixed gas discharge port 300 may be one or a plurality of mixed gas discharge ports 300 as long as the mixed gas can be discharged without any problem even if a small amount of silicon carbide or the like is formed. It is preferable that the opening diameter is about 1/5 to 1/2 of one side of the second surface so that the mixed gas can be discharged without any problem.

<Heater 400>
The heater 400 surrounds the four side surfaces 130 of the film forming chamber 100 and heats the film forming chamber 100. By controlling the heater 400, the temperature of the film forming chamber 100 can be controlled to a temperature suitable for forming a film on the substrate. As the heater 400, a heater useful for the thermal CVD method can be used, and for example, a tubular carbon heater or a cantal heater can be used.

<Board holder 500>
FIG. 4 shows a schematic view of the substrate holder 500. FIG. 4A is a side view of the substrate holder 500 holding the substrate 600, and FIG. 4B is a front view of the substrate holder 500 seen from the first surface 110 side inside the film forming chamber 100. The substrate holder 500 can hold a plurality of substrates 600 by stacking the substrates 600 at equal intervals in a non-contact manner, and the substrate 600 is placed between the first surface 110 and the second surface 120 of the film forming chamber 100. The film formation target surface 610 can be installed in parallel with the side surface 130 of the film formation chamber 100.

In FIG. 4, the substrate holder 500 can hold the substrate 600 by sandwiching the substrate 600 from two upper and lower positions by the upper holding rod 510 and the lower holding rod 520, and both the upper holding rod 510 and the lower holding rod 520 are the substrate 600. It has grooves 511 and 521 for holding the above. However, the substrate holder is not limited to this, and the substrate can be held at three or four places by having holding rods at the front and back in addition to the top and bottom.

The substrate holder 500 is involved in film formation because, for example, both the upper holding rod 510 and the lower holding rod 520 are in close contact with the upper side surface 130a and the lower side surface 130b of the side surface 130 of the film forming chamber 100. It is possible to prevent the mixed gas that is not mixed from flowing from the mixed gas ejection port 200 toward the mixed gas discharge port 300 and being discharged in a large amount from the film forming chamber 100.

In FIG. 4B, the film forming target surface 610 of the substrate 600 is installed in parallel with the left side surface 130c and the right side surface 130d of the side surface 130 of the film forming chamber 100, and the upper side surface 130a and the lower side surface 130b. It is installed vertically. However, by changing the shape of the substrate holder 500, the film formation target surface 610 of the substrate 600 can be installed perpendicularly to the left side surface 130c and the right side surface 130d, and can be installed parallel to the upper side surface 130a and the lower side surface 130b. .. That is, the substrate 600 may be laminated in the vertical direction or may be laminated in the horizontal direction. However, if the substrate 600 is installed so that the film-forming target surface 610 faces the mixed gas ejection port 200 and the film-forming target surface 610 is parallel to the first surface 110 and the second surface 120, the substrate 600 is installed between the substrates. This is not preferable because the mixed gas does not flow uniformly.

Further, the width 700 of the gap between the film-forming target surface 610 and the left side surface 130c of the substrate 600 and the width 710 of the gap between the right side surface 130d are the same as the width 720 of each gap between the substrates 600 laminated at equal intervals. In this case, since the mixed gas flows uniformly through these gaps, it is possible to form a film having little variation in thickness between the substrates or on the same surface to be formed.

<Ejection speed of mixed gas>
FIG. 5 shows a schematic diagram illustrating the ejection of the mixed gas. It schematically shows the spread of the mixed gas when the collision between molecules in the mixed gas is ignored, and it diffuses naturally from the mixed gas outlet 200 on the first surface without pressurizing the mixed gas. Let Vd be the diffusion rate of Vd, and Vg be the ejection rate when the mixed gas is pressurized and ejected from the mixed gas outlet 200.

When the diffusion speed Vd is faster than the ejection speed Vg, the diffusion of the mixed gas 800 proceeds slowly (FIG. 5A), so that the amount of the raw material gas supplied to the film forming chamber 100 is small and the film forming rate is slow. There is a risk of becoming. The temperature of the mixed gas outlet is lowered (for example, 1200 K or less) by providing a certain distance between the substrate 600 and the mixed gas outlet 200 in the film forming chamber 100 so that the mixed gas outlet 200 is not formed by the mixed gas. If control is attempted, it will take longer to form a film because there is a distance before the mixed gas 800 reaches the substrate 600.

<Ejection speed control means>
Therefore, the film forming apparatus 1000 of the present invention includes an ejection speed control means capable of making the ejection speed of the mixed gas ejected from the mixed gas ejection port 200 faster than the diffusion speed of the mixed gas. By making the ejection speed Vg faster than the diffusion velocity Vd (FIG. 5B), the mixed gas 810 is forcibly discharged from the mixed gas ejection port 200. As a result, even when the distance between the substrate 600 and the mixed gas ejection port 200 is provided to some extent in the film forming chamber 100, it is possible to suppress a decrease in the film forming speed. That is, while maintaining the same film forming speed as the conventional method, it is possible to prevent the mixed gas ejection port 200 from forming a film by the mixed gas and reducing the diameter and the mixed gas ejection port 200 from being blocked. be able to.

Forcibly discharging the mixed gas 810 from the mixed gas outlet 200 in order to make the ejection speed Vg faster than the diffusion velocity Vd is, for example, adjusting the amount of gas by an ejection speed control means such as a regulator, a compressor, or a suction device. It is possible by doing. For example, by setting the ejection speed Vg to 0.4 m / sec or more, the diameter of the mixed gas ejection port 200 becomes smaller due to the deposition of the mixed gas while maintaining the same film formation rate as the conventional method. , It is possible to easily prevent the mixed gas outlet 200 from being blocked. Further, when the ejection speed Vg is 1 m / sec or more, the film forming speed can be clearly increased as compared with the conventional method, and the film forming processing time can be shortened more effectively. When a plurality of mixed gas outlets 200 are provided in the film forming apparatus 1000 of the present invention, the ratio of the number of substrates 600 that can be held by the substrate holder 500 to the number of mixed gas outlets 200 is 1: 1. It is preferably 0.4 to 1.5. If the ratio of the number of substrates 600 that can be held by the substrate holder 500 to the number of ports of the mixed gas outlet 200 is 1: 0.4 to 1.5, the above-mentioned uniformity of gas speed and gas flow rate is satisfied. At the same time, it is possible to prevent a decrease in the film formation rate.

In the film forming apparatus 1000 of the present invention, the shortest distance between the mixed gas ejection port 200 and the substrate holder 500 is preferably 150 mm or more. The optimum shortest distance differs depending on the ejection speed and gas flow rate of the mixed gas 810 and the number of mixed gas ejection ports 200, but if the shortest distance is 150 mm or more, the area around the substrate 600 in the film forming chamber 100 is formed. The temperature around the mixed gas ejection port 200 can be sufficiently lowered from the film temperature. As a result, it is possible to easily prevent the mixed gas outlet 200 from becoming smaller in diameter due to the film formation of the mixed gas and the mixed gas outlet 200 from being blocked.

(Other configurations)
The film forming apparatus 1000 according to the embodiment of the present invention may have a further configuration in addition to the above configuration. For example, as shown in FIG. 1, the film forming chamber 100 is inserted into the first surface 110 and the second surface 120 inside, for example, a carbon cylindrical outer cylinder 1100 and the outer cylinder 1100. Ceramic furnace core tube 1300, outer cylinder 1100 and ceramic core tube in which an inert gas such as Ar gas is circulated between the holding jig 1200 and the outer cylinder 1100 fixed from the outside of the outer cylinder 1100. A fixed flange 1400 for fixing the 1300 at both ends thereof, and a housing 1500 for accommodating the film forming chamber 100 together with the outer cylinder 1100 and the ceramic core tube 1300 may be provided. Further, although not shown, a temperature measuring means such as a thermometer for measuring the temperature inside the film forming chamber 100, the temperature of the first surface 100, and the temperature of the mixed gas ejection port 200, and a switch for controlling the heat generation of the heater 400. Etc., a power source for generating heat, and the like can be provided.

[Film film method]
Next, as an example of the film forming method of the present invention, a film forming method using the film forming apparatus 1000 will be described. The film forming method of the present invention includes a film forming step.

<Film formation process>
In the film forming step, in the film forming chamber 100, the substrates 600 are laminated on the substrate holder 500 at equal intervals in a non-contact manner, and the film forming target surface 610 is installed parallel to the side surface 130 on a plurality of substrates 600. , The mixed gas 810 is ejected from the plurality of mixed gas outlets 200 into the film forming chamber 100, the mixed gas 810 is discharged from the film forming chamber 100 from the mixed gas discharge port 300, and the mixed gas 810 is discharged from the film forming target surface 610. This is a step of forming a film on the substrate 600 by circulating in a direction parallel to the above. When the film is formed in this way, it is possible to form a film having little variation in thickness between the substrates or on the same surface to be formed.

Further, the width 700 of the gap between the film-forming target surface 610 and the left side surface 130c of the substrate 600 and the width 710 of the gap between the right side surface 130d are the same as the width 720 of each gap between the substrates 600 laminated at equal intervals. In this case, since the mixed gas flows uniformly through these gaps, it is possible to form a film having less variation in thickness between the substrates or on the same surface to be formed.

For example, as described with reference to FIG. 5, it is preferable that the ejection speed Vg of the mixed gas 810 ejected from the mixed gas ejection port 200 is faster than the diffusion velocity Vd of the mixed gas 810.

Examples of the film forming method of the present invention include a film forming method of a silicon carbide polycrystalline film. In this case, the silicon source gas and the carbon source gas, which are the raw materials for silicon carbide, serve as the raw material gas, and the raw material gas and the rare gas such as argon gas and helium gas, hydrogen gas, etc., which have a role of transporting these raw material gases. The mixed gas 810 is a mixture of the above carrier gases. The mixed gas 810 may further contain a dopant gas such as nitrogen gas or an argon gas as appropriate.

The silicon source gas is not particularly limited as long as a silicon carbide polycrystalline film can be formed on the substrate 600 without any problem. For example, one or more selected from the group consisting of the monomers SiH ₄ , SiH ₃ Cl, SiH ₂ Cl ₂ , SiHCl ₃ , and SiCl ₄ can be used as the silicon source gas.

The carbon source gas is not particularly limited as long as a silicon carbide polycrystalline film can be formed on the substrate 600 without any problem. Since it is in a gas state near room temperature and is convenient for handling, it is preferable to use a carbon source gas composed of a saturated hydrocarbon having 5 or less carbon atoms or an unsaturated hydrocarbon having 5 or less carbon atoms. , One or a mixture of two or more of these can be preferably used. In particular, one or more selected from hydrocarbons having 5 or less carbon atoms, methane, ethane, propane, butane, or a hydrocarbon gas similar thereto can be appropriately used as the carbon source gas.

When forming a silicon carbide polycrystalline film, it is preferable that the temperature inside the film forming chamber 100 is 1400 K to 1700 K and the temperature of the first surface 110 is 1100 K or less. The temperature inside the film forming chamber 100 is an important condition for forming the silicon carbide polycrystalline film on the substrate 600. If the temperature in the room is low, the silicon carbide polycrystalline film may not be formed, or the film forming speed may be slowed down to reduce the production efficiency. Further, a large amount of raw material gas that is not involved in film formation is discharged from the film forming chamber, which may increase the loss of the raw material gas. Further, if the temperature in the room is high, epitaxial growth may occur, and the film formation target surface 610 near the mixed gas ejection port 200 corresponding to the upstream side of the mixed gas 810 is likely to be formed, which corresponds to the downstream side of the mixed gas 810. The film formation target surface 610 near the mixed gas discharge port 300 may be difficult to form, and the film thickness of the silicon carbide polycrystal film may vary significantly on the same film formation target surface 610. By setting the temperature inside the film forming chamber 100 to 1400K to 1700K, it is possible to uniformly form a silicon carbide polycrystalline film without lowering the production efficiency.

The temperature of the first surface 110 is set so that the silicon carbide polycrystalline film is not deposited on the mixed gas ejection port 200 and is not blocked, and the ejection of the mixed gas 810 is not difficult to control. It is an important condition. If the temperature of the first surface 110 is high, the silicon carbide polycrystalline film is deposited on the mixed gas outlet 200, which may make it difficult to control the ejection of the mixed gas 810, or the mixed gas outlet 200 is blocked. There is a risk of Further, there is no problem even if the temperature of the first surface 110 is low, but if the temperature of the first surface 110 is low, it may be difficult to control the temperature inside the film forming chamber 100. Considering these points, the temperature of the first surface 110 is preferably 1100 K or less, more preferably about 600 K to 1000 K.

Further, when forming a silicon carbide polycrystalline film, the temperature of the mixed gas outlet 200 is preferably 1200 K or less. The temperature of the mixed gas outlet 200 is important so that the silicon carbide polycrystalline film is not deposited on the mixed gas outlet 200 and is not blocked, and the ejection of the mixed gas 810 is not difficult to control. It becomes a condition. If the temperature of the mixed gas outlet 200 is high, a silicon carbide polycrystalline film is deposited on the mixed gas outlet 200, which may make it difficult to control the ejection of the mixed gas 810, or the mixed gas outlet 200 may be blocked. There is a risk of being lost. Further, although there is no problem even if the temperature of the mixed gas ejection port 200 is low, there is a possibility that it becomes difficult to control the temperature inside the film forming chamber 100 because the temperature of the first surface 110 is low. Considering these points, the temperature of the mixed gas outlet 200 is preferably 1200 K or less, more preferably about 600 K to 1000 K.

The film thickness of the silicon carbide polycrystalline thin film to be grown on the film formation target surface 610 of each substrate 600 can be appropriately set and is not particularly limited. Generally, the film thickness can be in the range of about 0.2 to 5 mm.

Further, as the film forming method of the present invention, a film forming method of a silicon carbide single crystal film can be mentioned. In this case, the silicon source gas and the carbon source gas, which are the raw materials for silicon carbide, serve as the raw material gas, and the raw material gas and the rare gas such as argon gas and helium gas, hydrogen gas, etc. The mixed gas 810 is a mixture of the above carrier gases. The mixed gas 810 may further contain a dopant gas such as nitrogen gas or an argon gas as appropriate.

The silicon source gas is not particularly limited as long as a silicon carbide polycrystalline film can be formed on the substrate 600 without any problem. For example, one or more selected from the group consisting of the monomers SiH ₄ , SiH ₃ Cl, SiH ₂ Cl ₂ , SiHCl ₃ , and SiCl ₄ can be used as the silicon source gas.

The carbon source gas is not particularly limited as long as a silicon carbide polycrystalline film can be formed on the substrate 600 without any problem. Since it is in a gas state near room temperature and is convenient for handling, it is preferable to use a carbon source gas composed of a saturated hydrocarbon having 5 or less carbon atoms or an unsaturated hydrocarbon having 5 or less carbon atoms. , One or a mixture of two or more of these can be preferably used. In particular, one or more selected from hydrocarbons having 5 or less carbon atoms, methane, ethane, propane, butane, or a hydrocarbon gas similar thereto can be appropriately used as the carbon source gas.

Further, when forming a silicon carbide single crystal film, the ratio of the number of carbon atoms in the carbon source gas to the number of silicon atoms in the silicon source gas (C / Si) is important, and C / Si is set to 0. By controlling the ratio to 7 to 1.3, it becomes easy to epitaxially grow a thin film of a silicon carbide single crystal on the substrate 600, and the growth rate can be increased, leading to an improvement in productivity. If C / Si deviates from 0.7 to 1.3, the balance of the abundance ratios of silicon atoms and carbon atoms becomes unbalanced, which may make film formation difficult or slow down the film formation rate. , Raw material gas that is not involved in film formation may increase and be wasted. For example, if C / Si is less than 0.7, unreacted Si may adhere to the film (droplet) in a metallic state, which causes defects. Further, if C / Si exceeds 1.3, a surface step called bunching may occur, which may adversely affect the fabrication of the device. More preferably, C / Si is 0.8 to 1.2.

The growth rate of the silicon carbide single crystal thin film is preferably 10 μm / hour to 70 μm / hour, and the silicon material gas at that time has a concentration of 1 volume% of the silicon source gas mentioned as a preferable example above. It is preferably 10% by volume, preferably 2% to 4% by volume. On the other hand, for the carbon material gas, the concentration of the carbon source gas mentioned as a preferable example is preferably 0.01% by volume to 1% by volume or less, preferably 0.02% by volume to 0.06. It should be% by volume. In addition, this concentration range is an example of the case of C ₃ H ₈ as an example, and when another carbon source gas is used with this concentration range as a guide, the amount of carbon (C) is equal to the amount. It should be changed so that. For example, when methane (CH ₄ ) is used, the upper limit and the lower limit of this concentration range may be tripled.

As for the growth pressure of the silicon carbide single crystal thin film, the general conditions for CVD growth of the silicon carbide thin film can be adopted as they are, as with the growth temperature. For example, the growth pressure is preferably in the range of 10,000 Pa to 110,000 Pa.

The film forming method of the present invention is not limited to the method for forming a silicon carbide polycrystalline film or a silicon carbide single crystal film. For example, it is a useful method for forming a film of titanium nitride, aluminum nitride, titanium carbide, diamond-like carbon and the like.

(Other processes)
The film forming method of the present invention can include other steps in addition to the above-mentioned film forming step. For example, a step of stacking the substrates 600 on the substrate holder 500 at equal intervals in a non-contact manner and installing the substrate 600 on the substrate holder 500, or a step of installing the substrate holder 500 on which the substrate 600 is installed in the film forming chamber 100 Examples thereof include a step of raising the film forming apparatus 1000 into a state in which a film can be formed, a step of cooling the film forming chamber after the film forming step, and a step of taking out the substrate after the film forming from the film forming chamber 100.

Further, in the film forming method of the present invention, a support substrate such as a plurality of Si substrates or C substrates can be used as a substrate 600, and a silicon carbide polycrystalline thin film can be grown on each of the film formation target surfaces 610. The number of substrates 600 in one film forming process is not particularly limited, but it is possible to simultaneously form a film from 5 to 10 substrates to 20 to 30 or more substrates 600. The substrate 600 is not limited to the support substrate, and a suitable substrate 600 can be appropriately selected and used as the substrate.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples. The present invention is not limited to the following contents.

[Example 1]
As the substrate 600, nine carbon substrates having a diameter of 4 inches (100 mm) and a thickness of 1 mm are prepared, and using the film forming apparatus 1000 shown in FIG. 1, both sides of the substrate 600 become the film forming target surface 610 by the thermal CVD method. A film forming step of forming a silicon carbide polycrystalline film was carried out. After the film forming step, the state of precipitation of silicon carbide at the mixed gas ejection port 200 was confirmed, and the film thickness of the formed silicon carbide polycrystalline film was measured to evaluate the variation in film thickness.

(Film formation device 1000)
The outer cylinder 1100 has a tubular shape formed from graphite-made crucibles at both ends, and is inserted into a ceramic core tube 1300. Both ends of the ceramic core tube 1300 and the outer cylinder 1100 are sealed with a metal fixing flange 1400. Then, the film forming chamber 100 is fixed inside the outer cylinder 1100 by the holding jig 1200. The graphite mixed gas introduction pipe 210 is inserted and installed in the holding jig 1200 and the first surface 100 so that the mixed gas ejection port 200 is located inside the film forming chamber 100. Then, the mixed gas discharge pipe 310 made of graphite is inserted into the holding jig 1200 and the second surface 120 so that the mixed gas discharge port 300 is located inside the film forming chamber 100 and installed. Further, a cylindrical graphite heater 400 surrounding the ceramic core tube 1300 is installed, and further, a housing 1500 for accommodating the film forming chamber 100 together with the outer cylinder 1100 and the ceramic core tube 1300 is provided. Then, the mixed gas 810 supplied to the film forming chamber 100 can be discharged from the film forming apparatus 1000 to the outside by using a vacuum pump (not shown) connected to the mixed gas discharge pipe 310.

In the film forming apparatus 1000, the ceramic core tube 1300 has an outer diameter of 210 mm, an inner diameter of 190 mm, a uniform thickness, and a length of 700 mm. The outer cylinder 1100 has an outer diameter of 180 mm, an inner diameter of 170 mm, a uniform thickness, and a length of 700 mm. Further, the film forming chamber 100 has a rectangular parallelepiped shape having an outer shape of 118 mm square and a length of 320 mm, and an inner shape of a rectangular parallelepiped shape having an inner shape of 110 mm square and a length of 320 mm, and has a uniform thickness.

(Gas outlet 200)
As shown in FIG. 2, four mixed gas outlets 200 having an inner diameter of 12 mm are arranged in a row on the first surface 110. The four mixed gas outlets 200 are arranged at equal intervals of 22 mm at the center of the pipe. Further, the row of the mixed gas ejection ports 200 is arranged at the center of the first surface 110 in the width direction (direction orthogonal to the row).

(Installation of board 600)
As shown in FIG. 4, nine substrates 600 were installed in the substrate holder 500. The substrate 600 was installed in the film forming chamber 100 in a state of being fixed to the substrate holder 500 by the grooves 511 and 521. As shown in FIG. 4B, the upper holding rod 510 of the substrate holder 500 is brought into close contact with the upper side surface 130a so that the mixed gas 810 does not enter between the upper holding rod 510 and the lower holding rod 520. The mixed gas 810 was brought into close contact with the lower side surface 130b so as not to enter the lower side surface 130b. The width of the gap 700 between the film-forming target surface 610 and the left side surface 130c of the substrate 600, the width 710 of the gap between the right side surface 130d, and the width 720 of each gap between the substrates 600 laminated at equal intervals are the same. It was set to 10 mm. The shortest distance between the mixed gas ejection port 200 and the substrate holder 500 was set to 150 mm.

(Silicon carbide polycrystalline film formation)
Ar gas was flowed between the outer cylinder 1100 and the ceramic core tube 1300 and in the housing 1500 in order to prevent oxidation of the graphite material. Then, after the inside of the film forming chamber 100 is evacuated by a vacuum pump (not shown), the film forming chamber 100 is introduced into the film forming chamber 100 at a flow rate of 200 cm ^{3 /} min using a mixed gas introduction pipe 210. The pressure inside was adjusted to atmospheric pressure (101,325 Pa). After that, the temperature inside the film forming chamber 100 was raised to 1550 K while maintaining the temperature of the first surface 110 at 1100 K or less and the temperature of the mixed gas ejection port 200 at 1200 K or less while keeping the pressure constant. Then, the flow rate of hydrogen gas introduced into the film forming chamber 100 was increased to 6.5 liters per minute. After holding this state for 3 minutes, SiC ₄ gas was mixed with 0.65 liters per minute, CH ₄ gas at 0.65 liters per minute, and argon gas at 3.2 liters per minute to make a mixed gas 810, and Vg> Vd. In this state, the formation of a silicon carbide polycrystalline film on the substrate 600 by thermal CVD was started.

After performing the film forming treatment for 10 hours, the supply of the mixed gas 810 and the heating by the heater 400 were stopped to cool the substrate 600 to room temperature, and then the substrate 600 on which the silicon carbide polycrystalline film was formed was taken out from the substrate holder 500. Then, the substrate 600 is exposed by grinding the outer periphery, the substrate 600 is fired in the air to be incinerated, and 18 silicon carbide polycrystalline substrates 650 are formed on the front surface and the back surface of the nine substrates 600. Obtained.

(Measurement of film thickness of silicon carbide polycrystalline substrate 650)
The film thickness of the silicon carbide polycrystalline substrate 650 was measured using an obliquely incident optical measuring instrument. The film thicknesses of each substrate were measured and averaged at a plurality of locations, and the film thicknesses of two silicon carbide polycrystalline substrates 650 obtained from the same substrate 600 were averaged. Table 1 shows the average value of the film thickness at each substrate position.

[Example 2]
In the film forming apparatus 1000 shown in FIG. 1, only one mixed gas outlet 200 is provided so that the center of the first surface 110 coincides with the center of the mixed gas outlet 200 having an inner diameter of 20 mm. Other than that, the film formation process was performed under the same conditions as in Example 1, the film thickness was measured, and the average value of the film thickness was calculated. The results are shown in Table 1.

[Example 3]
In the film forming apparatus 1000 shown in FIG. 1, two mixed gas ejection ports 200 having an inner diameter of 20 mm are provided on the first surface 110. The first surface 110 is a square having a side of 110 mm, and the two mixed gas outlets 200 are located so that the center of the mixed gas outlet 200 is located at a position 35 mm from the upper end thereof and a position 35 mm from the lower end thereof. Was placed. The two mixed gas outlets 200 are arranged at the center of the first surface 110 in the width direction. Other than that, the film formation process was performed under the same conditions as in Example 1, the film thickness was measured, and the average value of the film thickness was calculated. The results are shown in Table 1.

[Comparison example]
FIG. 6 shows a schematic view showing a cross section of a side surface of the film forming apparatus 2000 of the comparative example. The film forming apparatus 2000 includes a film forming chamber 2100, a mixed gas ejection port 2200, a mixed gas discharge port 2300, a heater 2400, and a substrate holder 2500. Although each part of the film forming apparatus 2000 is arranged differently from that of the film forming apparatus 1000, it is made of the same material and has the same function.

The film forming chamber 2100 has four side surfaces connecting the first non-heated surface 2110, the second non-heated surface 2120 facing the first non-heated surface 2110, and the first non-heated surface 2110 and the second non-heated surface 2120. It has a rectangular parallelepiped inner shape consisting of 2130. The heater 2400 surrounds the four side surfaces 2130 of the film forming chamber 2100 and heats the film forming chamber 100. That is, the first non-heated surface 2110 in the film forming apparatus 2000 corresponds to the first surface 110 in the film forming apparatus 1000, and the second non-heated surface 2120 in the film forming apparatus 2000 corresponds to the second surface 120 in the film forming apparatus 1000. The four side surfaces 2130 of the film forming apparatus 2000 correspond to the side surfaces 130 of the film forming apparatus 1000. In addition, "non-heating" means that it does not face the heater 2400 and is not directly heated.

A plurality of mixed gas outlets 2200 are formed in one mixed gas introduction pipe 2210. The mixed gas introduction pipe 2210 is provided in the film forming chamber 2100 at a position facing one side surface 2130, and the mixed gas ejection port 2200 is directed to the opposite side surface 2130. As described above, the mixed gas ejection port 2200 is arranged on the reaction blade in the film forming chamber 2100, and is in an environment where the temperature is about the same as that of the substrate 600.

A plurality of mixed gas outlets 2300 are formed on the side surface 2130 to which the mixed gas outlet 2200 is directed. An outer cylinder 2140 is provided so as to surround the four side surfaces 2130 and the second non-heated surface 2120, and the mixed gas that has passed through the mixed gas discharge port 2300 passes through the space between the outer cylinder 2140 and the side surface 2130. It is discharged.

The substrate holder 2500 is arranged between the mixed gas introduction pipe 2210 and the side surface 2130 in which the mixed gas discharge port 2300 is formed. The substrate 600 held by the substrate holder 2500 is parallel to the direction in which the mixed gas flows (the direction opposite to the mixed gas introduction pipe 2210 and the side surface 2130 in which the mixed gas discharge port 2300 is formed).

The heater 2400 is arranged so as to surround the four side surfaces 2130 and the outer cylinder 2140. Therefore, the mixed gas introduction pipe 2210 in which the mixed gas outlet 2200 is formed is surrounded by the heater 2400.

A substrate 600 similar to that of Examples 1 to 3 was prepared, and a film forming process was performed by CVD growth using a film forming apparatus 2000 as shown in FIG. The film formation conditions such as the type of gas used, the film formation temperature, and the gas pressure were the same as in Examples 1 to 3.

In Examples 1 to 3 and Comparative Example, it was evaluated whether or not silicon carbide adhered to the mixed gas outlet 200 (whether or not SiC was precipitated). The results are shown in Table 2.

In any of the examples, it was possible to prevent silicon carbide from depositing on the mixed gas outlet 200. Further, in Examples 1 and 3 using only a plurality of mixed gas outlets 200, it is possible to alleviate the variation in film thickness between the substrates as compared with Example 2 in which only one mixed gas outlet 200 is used. did it.

[Summary]
As described above, it is clear that the film forming apparatus and the film forming method of the present invention can prevent silicon carbide from being deposited on the gas outlet.

100 Formation chamber 110 1st surface 110a 1st surface 110b 1st surface 120 2nd surface 130 Side surface 130a Upper side surface 130b Lower side surface 130c Left side surface 130d Right side surface 200 Mixed gas outlet 210 Mixed gas inlet pipe 300 Mixed gas outlet 310 Mixed gas discharge pipe 400 Heater 500 Substrate holder 510 Upper holding rod 511 Groove 520 Lower holding rod 521 Groove 600 Substrate 610 Formation target surface 800 Mixed gas 810 Mixed gas 1000 Formation device 1100 Outer cylinder 1200 Holding jig 1300 Ceramic core tube 1400 Fixed flange 1500 Housing Vg Ejection speed Vd Diffusion speed

Claims (9)

A film forming chamber having a rectangular parallelepiped inner shape composed of a first surface, a second surface facing the first surface, and four side surfaces connecting the first surface and the second surface.
A mixed gas ejection port that is located on or near the first surface and ejects a mixed gas containing a raw material gas and a carrier gas into the film forming chamber.
A mixed gas discharge port located on or near the second surface and discharging the mixed gas from the film forming chamber,
A heater that surrounds the four side surfaces and heats the film formation chamber,
A plurality of substrates can be laminated and held at equal intervals in a non-contact manner, and the film-forming target surface of the substrate can be formed between the first surface and the second surface of the film-forming chamber. A board holder that can be installed parallel to the side,
A film forming apparatus including an ejection speed control means capable of making the ejection speed of the mixed gas ejected from the mixed gas ejection port faster than the diffusion speed of the mixed gas. The film forming apparatus according to claim 1, wherein the plurality of the mixed gas ejection ports are arranged in the stacking direction of the plurality of substrates. The film forming apparatus according to claim 1 or 2, wherein the shortest distance between the mixed gas outlet and the substrate holder is 150 mm or more. A film forming method using the film forming apparatus according to any one of claims 1 to 3.
In the film forming chamber, the mixed gas ejection port is provided to a plurality of the substrates in which the substrates are laminated on the substrate holder at equal intervals in a non-contact manner and the film formation target surface is installed parallel to the side surface. The mixed gas is ejected into the film forming chamber, and the mixed gas is discharged from the film forming chamber from the mixed gas discharge port, and the mixed gas is circulated in a direction parallel to the film forming target surface. , A film forming method including a film forming step of forming a film on the substrate. The film forming method according to claim 4, wherein the ejection speed of the mixed gas ejected from the mixed gas ejection port is made faster than the diffusion speed of the mixed gas. A method for forming a silicon carbide polycrystal film, the raw material gas contains a silicon source gas and a carbon source gas, and the silicon source gas is SiH ₄ , SiH ₃ Cl, SiH ₂ Cl ₂ , SiHCl ₃ , and SiCl. One or more selected from the group consisting of ₄ , the carbon source gas is one or more selected from hydrocarbons having 5 or less carbon atoms, and the carrier gas is hydrogen gas. The film forming method according to claim 4 or 5. The film forming method according to claim 6, wherein the temperature inside the film forming chamber is 1400 K to 1700 K, and the temperature of the first surface is 1100 K or less. The film forming method according to claim 6 or 7, wherein the temperature of the mixed gas ejection port is 1200 K or less. A method for forming a silicon carbide single crystal film, the raw material gas contains a silicon source gas and a carbon source gas, and the silicon source gas is SiH ₄ , SiH ₃ Cl, SiH ₂ Cl ₂ , SiHCl ₃ , and SiCl. One or more selected from the group consisting of ₄ , the carbon source gas is one or more selected from hydrocarbons having 5 or less carbon atoms, and the carrier gas is hydrogen gas. And
The claim that a thin film of silicon carbide single crystal is epitaxially grown on the substrate by setting the ratio (C / Si) of the number of carbon atoms in the carbon source gas to the number of silicon atoms in the silicon source gas to 0.7 to 1.3. The film forming method according to 4 or 5.

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