JP4381489B2 - Chemical vapor deposition equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a chemical vapor deposition apparatus, and is particularly suitable for application to a metal organic chemical vapor deposition (MOCVD) apparatus.
[0002]
[Prior art]
Light-emitting elements such as LEDs and semiconductor lasers and high-frequency transistors for communication manufactured using Group III-V compound semiconductors, together with silicon (Si) -based elements, are the hardware infrastructure of the modern information communication society. It is an important element that constitutes.
[0003]
The III-V compound semiconductor device is complementary to the Si-based device in a region that cannot be realized by Si, such as a semiconductor laser, due to a structure using a heterojunction of a III-V compound semiconductor. Have a role.
[0004]
Further, in the manufacture of compound semiconductor devices such as III-V compound semiconductor devices, the heteroepitaxy technology is an important technology, except for devices with a simple structure such as MESFET. It is no exaggeration to say that it is supported by epitaxy technology. As the heteroepitaxy technique, molecular beam epitaxy and chemical vapor deposition, particularly MOCVD, are currently main techniques, and have been studied academically since the 1960s.
[0005]
The MOCVD method has been put into practical use since about 1983 as an epitaxial growth technique for manufacturing a GaAs semiconductor laser, and currently, an MOCVD apparatus that performs epitaxial growth on a large number of substrates at a time is commercially available. There are various methods in the elemental technology of the MOCVD apparatus for a large number of substrates. That is, the susceptor has a barrel type, pancake type, etc., and a gas flow type includes a high flow rate horizontal type, a high-speed rotation type, a vertical downflow type, etc. There are those that are placed above the flow (face down) and those that are placed below the gas flow (face up), and there are high-frequency heating methods, resistance heating methods, lamp heating methods, etc., and these element technologies are combined. Various types of MOCVD apparatuses are used.
[0006]
A conventional MOCVD apparatus used for epitaxial growth of a group III-V compound semiconductor uses gallium (Ga), aluminum (Al) or indium (In) as a group III element and arsenic (As) or phosphorus (as a group V element). P) was used and the growth temperature was at most 800 ° C. On the other hand, ammonia (NH_Three) Based on GaN-based semiconductor elements have been developed, and the demand for MOCVD equipment for epitaxially growing GaN-based semiconductors has increased.
[0007]
[Problems to be solved by the invention]
In a GaN-based semiconductor MOCVD apparatus, an organic group III metal and NH are formed on a substrate made of sapphire or SiC at a temperature of about 1000 ° C._ThreeTo grow a single crystal thin film. In the growth of this single crystal thin film, the gas composition and growth conditions for growing a high-quality crystal have already been scientifically announced and known. However, MOCVD equipment for realizing optimized gas composition and growth conditions for obtaining high-quality crystals has been modified according to the results of individual technological development, and is generally well known. Not. Among those MOCVD apparatuses, those relating to the reaction tube structure are known (for example, JP-A-2-288665, JP-A-2-61082, JP-A-4-94719). . However, it is difficult to apply these known techniques as they are to a MOCVD apparatus for a large number of substrates.
[0008]
Accordingly, an object of the present invention is to provide a chemical vapor deposition apparatus capable of realizing an optimized gas composition and growth conditions for obtaining a good quality crystal in epitaxial growth of a GaN-based semiconductor.
[0009]
[Means for Solving the Problems]
The present inventor has intensively studied to solve the above-described problems of the prior art. The outline will be described below.
[0010]
According to the inventor's knowledge, NH_ThreeThe MOCVD apparatus for growing GaN-based semiconductors using as the main material is NH_ThreeIn view of the above chemical characteristics, a technical idea different from the MOCVD apparatus for growing an As-based or P-based semiconductor is required. That is, NH_ThreeIn a MOCVD apparatus in which a GaN-based semiconductor is grown using as a main source gas, NH_ThreeLow decomposition efficiency, NH in gas phase_ThreeCarrier gas during crystal growth to optimize the carrier gas due to high-speed reaction between the III and III group raw materials, difficulty in supplying raw materials by thermal convection in high temperature growth of about 1000 ° C., and differences in raw material composition (or crystal composition) Changes in the composition of (e.g., H₂/ N₂This is different from the MOCVD apparatus for growing an As-based or P-based semiconductor in that a composition change) must be taken into consideration. In consideration of these matters, an example applied to an MOCVD apparatus for a large number of substrates has not been published.
[0011]
In general, the crystal growth rate depends on the gas flow rate in the vicinity of the substrate surface. Therefore, for example, when the substrate on which the crystal is grown is arranged on the circumference and the source gas is discharged from the center of the circumference, the gas flow that flows out from the center of the circumference spreads radially, and the circumference in the upstream of the gas flow On the other hand, since the downstream circumference becomes longer, the flow rate of the gas decreases, and the film thickness of the crystal grown film becomes non-uniform. This non-uniformity in film thickness can be improved by rotating the substrate. However, even if the crystal cannot be grown uniformly on the substrate even when the substrate is not rotated, it is not possible to guarantee further uniformity when the substrate is rotated. Therefore, if the gas flow rate in the periphery of the substrate is made equal in all parts of the substrate, it is possible to guarantee further uniformity of the thickness of the film on which the crystal is grown when the substrate is rotated. That is, in order to grow a compound semiconductor uniformly on a large number of substrates simultaneously, the source gas must be uniformly supplied onto each of the large number of substrates. It must flow at the same flow rate in every part of each of the multiple substrates. However, in the conventional MOCVD apparatus, it was not always possible to flow the carrier gas at an equal flow rate in every part of each substrate. Therefore, in order to cause the carrier gas to flow at the same flow velocity in all parts of each of the multiple substrates, the cross-sectional area increases from the upstream side of the gas passage toward the downstream side around the susceptor holding the substrate. In order to avoid this, it is preferable to configure so as to decrease.
[0012]
In order to prevent non-uniform gas flow due to thermal convection, the face-down method is ideal. However, in the face-down method, the substrate is attached to the susceptor by a mechanical fixing method using pins (screws), etc., so that the gas flow of the reaction gas is disturbed by the projections formed by the pins, etc. It happened. Then, due to the turbulence of the gas flow and the shadow effect, the crystal growth in the peripheral portion of the projection such as a pin becomes abnormal, and a defective portion such as a semiconductor element cannot be formed in that portion. Further, the substrate is soiled during the work of attaching and removing the substrate, and time is wasted in attaching and removing the substrate. In order to prevent these, it is only necessary not to use pins or the like to fix the substrate to the susceptor, and for that purpose, using a susceptor having an opening that exposes the surface on which the crystal is grown, It is effective to place a substrate with the growth surface facing downward in the opening.
[0013]
In addition, there are three main methods for heating these substrates. That is, the above-described high-frequency heating method, resistance heating method, and lamp heating method. However, in these heating methods, a plurality of substrates are arranged on a large integrated susceptor, and the entire large integrated susceptor is heated, so all the portions between the substrates are also heated, and the substrate It was not possible to efficiently heat only the above-described heating method.
[0014]
For example, in a method of heating a susceptor when using a pancake type susceptor, a carbon susceptor that rotates the substrate is complexly combined with a carbon susceptor that revolves the substrate, and the substrate placed on these carbon susceptors is combined. In order to heat, the carbon susceptor which revolves a board | substrate is heated first, the carbon susceptor which rotates a board | substrate is heated by heating the carbon susceptor which revolves a board | substrate, and conducting the heat to the carbon susceptor which rotates a board | substrate. Thus, in order to heat the substrate, the carbon susceptor that revolves a larger area of the substrate has to be heated, so that not only the thermal energy efficiency is poor, but also excess of the source gas outside the substrate Decomposition and precipitation were promoted, and the use efficiency of the raw material gas was deteriorated. Therefore, if the heat energy efficiency is improved by heating only the substrate without using a large integral susceptor, excessive decomposition and precipitation of the source gas outside the substrate can be reduced. Can do. For this purpose, it is effective to use a heating device that disposes a susceptor that supports only one substrate on one circumference and heats only the circumference.
[0015]
In addition, as is conventionally known, the growth of GaInN crystals can be performed using H as a carrier gas.₂A smaller amount of gas is desirable, whereas HGaN as a carrier gas is used for the growth of AlGaN crystals.₂It is desirable to have more gas. Therefore, in the case of growing a GaInN / AlGaN multi-layer film such as in the manufacture of a semiconductor laser, H₂Gas and N₂The composition change with the gas must be instantaneous. However, it is difficult to instantaneously switch a large amount of gas to a gas composition optimal for crystal growth. Therefore, in order to obtain a gas composition optimal for crystal growth instantaneously, it is only necessary to obtain a gas composition optimal for crystal growth by switching a small amount of gas. For this purpose, it is effective to provide a plurality of gas passages through which the carrier gas flows, and to obtain an optimum gas composition for crystal growth by changing the composition of the carrier gas flowing through one of the gas passages. is there.
[0016]
In addition, in the gas discharge, the number of gas discharge pipes connected to the MOCVD apparatus to discharge the gas to the outside is limited, and the gas flow velocity in the portion near the gas discharge pipe on the growth surface of the substrate (downstream) is The flow rate of gas in the portion farther from the gas discharge pipe (upstream) becomes smaller. That is, in the vicinity of the substrate surface, the flow rate of the reaction gas becomes non-uniform on the growth surface of the substrate, so that the rate of crystal growth becomes non-uniform and the film thickness of the epitaxially grown film becomes non-uniform. In order to prevent this, the gas flow rate may be made constant both in the portion far from the gas discharge pipe and in the near portion. For this purpose, it is effective to provide a gas constriction in the gas discharge pipe on the downstream side of the susceptor. The present invention has been devised based on the above studies.
[0017]
  That is, in order to achieve the above object, the first invention of the present invention is:
  Placed on one circumferenceAnd the substrate is arranged with the growth surface facing downwardMultiple susceptors,
  A plurality of gas passages for supplying reaction gas toward the susceptor;
  In a chemical vapor deposition apparatus having a heating means for heating a susceptor,
  The plurality of gas passages are configured by a space portion between a plurality of gas passage walls formed of a cylindrical portion and a flange-shaped flat plate portion at an upper portion thereof with a common central axis of the circumference. And a horizontal flow path is constituted by a space portion between the flat plate portions of the plurality of gas passage walls,
  The plurality of gas passages define the flow of the reaction gas to the susceptor and the plurality of gas passages.Flat part of gas passage wallIn addition, a gas constriction is provided on the circumference concentric with the circumference.,
  The outermost gas passage wall of the plurality of gas passage walls extends to the outside of the susceptor, and the cross-sectional area of the flow path between the gas passage wall and the susceptor decreases from the upstream side to the downstream side. Configured as
  The outermost gas passage of the plurality of gas passages and the gas passage immediately inside thereof constitute a gas passage for dummy gas.
  It is characterized by this.
[0018]
In the first invention, preferably, a gas constriction is provided in all of the plurality of gas passages.
[0019]
In the first invention, specifically, the plurality of gas passages include a first gas passage for a group III element source gas and a second gas passage for a group V element source gas, The gas passage and the second gas passage are configured to merge at an angle of 10 to 90 ° downstream of the gas constriction portion, and the gas flowing through the gas passage is sufficiently mixed at the junction. Move as close to the susceptor as possible. The supplied gas is NH_ThreeIn order to suppress the addition reaction, the distance from the susceptor to the meeting point is selected to be 2 to 15 cm, preferably 10 cm or less.
[0020]
In the first aspect of the invention, the plurality of gas passages are specifically, a first gas passage for a group III element source gas, a second gas passage for a group V element source gas, and an inert gas passage. A third gas passage for the carrier gas of the gas and a fourth gas passage for the carrier gas of the inert gas containing hydrogen, the third gas passage and the fourth gas passage being around the susceptor. The first gas passage and the second gas passage are configured to merge substantially in parallel with the gas passage after the merge.
[0021]
In the first aspect of the present invention, preferably, in the periphery of the susceptor, the cross-sectional area of the gas passage after the merging of the plurality of gas passages is configured to decrease from the upstream side to the downstream side of the gas passages, Specifically, the cross-sectional area of the gas passage after merging is formed by inclining the surface of the gas passage wall facing the susceptor out of the gas passage walls constituting the gas passage after merging with respect to the susceptor. Is configured to decrease from the upstream side toward the downstream side.
[0022]
  The second invention of this invention is:
  Placed on one circumferenceAnd the substrate is arranged with the growth surface facing downwardMultiple susceptors,
  A plurality of gas passages for supplying reaction gas toward the susceptor;
  In a chemical vapor deposition apparatus having a heating means for heating a susceptor,
  The plurality of gas passages are configured by a space portion between a plurality of gas passage walls formed of a cylindrical portion and a flange-shaped flat plate portion at an upper portion thereof with a common central axis of the circumference. And a horizontal flow path is constituted by a space portion between the flat plate portions of the plurality of gas passage walls,
  The plurality of gas passages regulate the flow of the reaction gas to the susceptor, and an annular rotating plate provided with a plurality of openings for installing the susceptor is provided in the plurality of gas passages.The gas in the innermost gas passagePart of the aisle wallAnd
  The outermost gas passage wall of the plurality of gas passage walls extends to the outside of the susceptor, and the cross-sectional area of the flow path between the gas passage wall and the susceptor decreases from the upstream side to the downstream side. Configured as
  The outermost gas passage of the plurality of gas passages and the gas passage immediately inside thereof constitute a gas passage for dummy gas.
  It is characterized by this.
[0023]
In the second aspect of the invention, typically, when the plurality of susceptors are installed in the plurality of openings of the rotating plate, the lower surface of the susceptor constitutes a part of the passage wall of the gas passage. The lower surface of the susceptor and the lower surface of the susceptor constitute the same surface.
[0024]
In the second aspect of the invention, specifically, the susceptor is configured to be revolved by the rotation of a rotating plate having a heat insulating property that holds the susceptor. In the second aspect of the invention, for example, the susceptor has a first gear on the outer periphery, and the first gear is connected to a second gear fixed to the chemical vapor deposition apparatus. The susceptor is configured to be able to rotate by rotating the first gear by the rotation of the rotating plate. The second gear is composed of a ring provided with a gear on the inner peripheral portion, a circular plate provided with a gear on the outer peripheral portion, or the like.
[0025]
In the second aspect of the invention, the lower surface of the rotating plate and the lower surface of the susceptor are on substantially the same plane in order to maintain a smooth gas flow.
[0026]
The third invention of the present invention is:
A plurality of susceptors arranged on one circumference;
A plurality of gas passages for supplying reaction gas toward the susceptor;
In a chemical vapor deposition apparatus having a heating means for heating a susceptor,
The susceptor includes a substrate holding unit having an opening for installing the substrate, and a substrate heating unit that transfers heat to the substrate to heat it.
It is characterized by this.
[0027]
In the third aspect of the invention, typically, the substrate holding part has a protrusion for holding the substrate at the lower part. In the third aspect of the invention, more specifically, the substrate heating unit is fixed in contact with the substrate installed on the substrate holding unit by its own weight, and is detachably attached to the substrate holding unit. It is done.
[0028]
The fourth invention of the present invention is:
A plurality of susceptors arranged on one circumference;
A plurality of gas passages for supplying reaction gas toward the susceptor;
In a chemical vapor deposition apparatus having a heating means for heating a susceptor,
The heating means includes an annular light source and an annular reflecting mirror for condensing light emitted from the light source on the susceptor.
It is characterized by this.
[0029]
In the fourth aspect of the invention, in order to efficiently heat the susceptor, the circular cross-sectional shape of the annular reflector is preferably an elliptical shape or an annular shape in which an annular light source is located at one focal point. A parabolic shape with the light source located at the focal point. In the fourth aspect of the present invention, the reaction system in which the heating means and the susceptor are placed is separated by a light passage plate made of, for example, quartz, and the inside of the heating means and a portion between the susceptor and the light passage plate. Is filled with inert gas. In the fourth aspect of the invention, typically, there is further provided an anti-fogging means for carrying out anti-fogging by blowing, for example, an inert gas onto the surface of the light passage plate where the susceptor is present.
[0030]
In the fourth aspect of the invention, specifically, it has an annular rotating plate provided with a plurality of openings for holding a plurality of susceptors, and the inner peripheral surface forms a light reflecting surface on the rotating plate. Two cylinders having different radii are provided so as to sandwich a plurality of openings concentrically with the rotating plate, and light reflection such as a gold (Au) film is provided on the surface of the two cylinders where the openings exist. A membrane is provided.
[0031]
  The fifth invention of the present invention is:
  A plurality of susceptors arranged on one circumference;
  A plurality of gas passages for supplying reaction gas toward the susceptor;
  Heating means for heating the susceptor;
  In a chemical vapor deposition apparatus having a gas exhaust means for exhausting a reaction gas,
  The plurality of gas passages define the flow of reactive gas to the susceptor, andThe gas exhaust means has an exhaust gas constriction.
  It is characterized by this.
[0032]
In the fifth aspect of the invention, typically, the gas exhaust means is disposed on the downstream side of the exhaust gas constriction, and is connected to an exhaust gas pipe connected to an exhaust gas pipe for exhausting the reaction gas to the outside of the chemical vapor deposition apparatus. It further has a part.
[0033]
In the fifth aspect of the invention, the exhaust gas constriction is composed of, for example, a thin plate having a plurality of minute openings and a groove.
[0034]
The sixth invention of the present invention is:
A plurality of susceptors arranged on one circumference;
A plurality of gas passages for supplying reaction gas toward the susceptor;
In a chemical vapor deposition apparatus having a heating means for heating a susceptor,
An attachable and detachable top plate that separates the reaction system where the susceptor is placed and the heating means;
A top plate support means for supporting the top plate
It is characterized by this.
[0035]
In the sixth aspect of the invention, preferably, the top plate is configured by combining a part made of quartz and a part made of metal such as stainless steel.
[0036]
In the sixth aspect of the invention, the top plate support means is specifically the central axis of the rotation means for rotating the rotary plate that holds the susceptor.
[0037]
In the present invention, typically, the reaction gas flowing in the gas passage is configured to flow parallel to the surface of the substrate installed in the susceptor.
[0038]
According to the first invention of the present invention configured as described above, a susceptor of a gas passage for arranging a plurality of susceptors on one circumference and supplying a reaction gas to the plurality of susceptors is provided. By providing the gas constriction part on the circumference concentric with the arranged circumference, the pressure loss in the gas passage of the reaction gas can be made smaller than the pressure loss in the gas constriction part, and the upstream side of the gas constriction part Therefore, the pressure of the reaction gas can be made uniform over the circumferential direction of the gas constriction portion.
[0039]
Further, according to the second aspect of the present invention, since the annular rotating plate forms the passage wall of the gas passage, the flow of the reaction gas to the susceptor can be reduced when the reaction gas is caused to flow in the gas passage. Can be prescribed.
[0040]
According to the third aspect of the present invention, the susceptor includes the substrate holding portion having an opening for holding the substrate and the substrate heating portion that transfers the heat to the substrate to heat the crystal, thereby allowing crystal growth. The substrate can be easily fixed to the susceptor without using pins or the like.
[0041]
According to the fourth aspect of the present invention, the heating means includes an annular light source and an annular reflecting mirror for condensing the light emitted from the light source on the susceptor, so that only the susceptor is provided. Can be heated.
[0042]
According to the fifth aspect of the present invention, the gas exhaust means for exhausting the reaction gas has the exhaust gas constriction, so that the pressure of the reaction gas can be made uniform over the circumferential direction of the exhaust gas constriction. can do.
[0043]
Further, according to the sixth aspect of the present invention, there is provided an attachable / detachable top plate for separating the reaction system in which the susceptor is placed and the heating means, and a top plate support portion for supporting the top plate. By doing so, the pressure applied to the top plate can be applied to the top plate support part.
[0044]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals.
[0045]
FIG. 1 shows the overall configuration of a horizontal MOCVD apparatus according to this embodiment.
[0046]
As shown in FIG. 1, the horizontal MOCVD apparatus according to this embodiment includes a gas line / gas supply system 1, a gas discharge unit 2, a rotation drive system 3, a susceptor / rotation ring plate 4, a top plate 5, and a heating device 6. Have The gas line / gas supply system 1 is for supplying, for example, a source gas such as a group III element or a group V element and a carrier gas such as an inert gas to the reaction section. The gas discharge part 2 is for discharging | emitting the exhaust gas after reaction outside. The rotational drive system 3 is for rotating the susceptor / rotating annular plate 4. The top plate 5 is for separating the reaction unit on which the susceptor / rotating ring plate 4 is placed and the heating device 6, and a portion of the top plate 5 immediately below the heating device 6 passes heating light. Be able to.
[0047]
FIG. 2 shows a radial cross section of the gas line / gas supply system 1. The gas line / gas supply system 1 is for supplying a source gas used for crystal growth and a dummy gas (carrier gas) that does not directly contribute to crystal growth to the substrate 8 placed on the susceptor 7. In this gas line / gas supply system 1, a plurality of gas passage walls 9 to 13 each having a cylindrical portion and a collar-shaped flat plate portion at the upper portion have a central axis OO in common and have a substantially constant interval therebetween. Are arranged and configured. And the space part between the gas passage wall 9 and the gas passage wall 10 comprises the 1st gas line 14 for flowing the source gas of a III group element, for example. Further, a space portion between the gas passage wall 10 and the gas passage wall 11 constitutes a second gas line 15 for flowing a source gas of a group V element, for example. Further, the space portion between the gas passage wall 11 and the gas passage wall 12 is, for example, N₂Gas and H₂A third gas line 16 for flowing a gas mixture is configured. Further, the space portion between the gas passage wall 12 and the gas passage wall 13 is, for example, N₂A fourth gas line 17 for flowing an inert gas is configured. III-group and V-group source gases and N₂A dummy gas such as a gas is configured to be introduced from a gas inflow terminal (not shown) such as a VCR joint attached to the side surface of the cylindrical portion of each gas passage wall 10-13.
[0048]
Further, the first gas line 14, the second gas line 15, the third gas line 16, and the fourth gas line 17 are vertically moved by the upper plate portions of the respective gas passage walls 10 to 13 at the upper part thereof. The horizontal flow paths have a stack structure, and when gas is introduced into these horizontal flow paths, the gas flows radially inside the horizontal flow paths. Gas constrictions 10a to 13a are respectively provided on the upper plate portions of the gas passage walls 10 to 13 in the middle portion of the horizontal flow paths on the circumferences concentric with the central axis OO. Here, the gas constriction portions 10a to 13a are provided separately from each other along the circumferential direction. FIG. 3 shows a cross section along the circumferential direction of the gas constriction 10a. The same applies to the gas constriction portions 11a to 13a. When the gas passes through these gas constrictions 10a to 13a, the pressure of the gas on the downstream side is lower by about 10 Torr than the gas pressure on the upstream side of these gas constrictions 10a to 13a. It is configured.
[0049]
Since the gas constriction portions 10a to 13a are provided in the middle portions of the upper plate portions of the first gas line 14 to the fourth gas line 17, the first gas line 14 and the second gas are provided. When the gas flows through the line 15, the third gas line 16, and the fourth gas line 17, the loss of gas pressure in the horizontal flow path portion is smaller than the loss of gas pressure in the gas constriction portions 10 a to 13 a. Since it becomes small, the pressure of gas can be made uniform over the circumference | surroundings of gas constriction part 10a-13a, and gas can be uniformly flowed radially.
[0050]
Further, the first gas line 14 and the second gas line 15 are configured to join at an angle on the upstream side of the periphery of the susceptor 7. Here, the upper and lower widths of the gas lines in the merged portion are larger than the sum of the upper and lower widths of the first gas line 14 and the upper and lower widths of the second gas line 15 in the non-merged portion. It is comprised so that it may become small. That is, the group III element source gas flowing in the first gas line 14 and the group V element source gas flowing in the second gas line 15 merge before being supplied to the susceptor 7, that is, upstream. In addition, the cross-sectional area of the gas flow decreases toward the downstream side. Here, even if these source gases that flow radially and uniformly are merged, the uniformity of the flow of these source gases is maintained.
[0051]
Thus, the first gas line 14 and the second gas line 15 form an angle, and the upper and lower widths of the gas line after joining the group III element source gas and the group V element source gas are Since the total of the upper and lower widths of the respective gas lines before the merging of the raw material gases is made smaller, the group III element source gas and the group V element source gas are sufficiently provided upstream of the susceptor 7. Can be mixed.
[0052]
By the way, the optimum angle formed by the first gas line 14 and the second gas line 15 depends on the distance from the point where they merge to the susceptor 7. That is, for example, if the distance from the point where the first gas line 14 and the second gas line 15 merge to the susceptor 7 is short, in order to quickly mix the group III element and group V element source gases flowing therethrough The angle must be increased, and if the distance is long, the angle must be decreased. For this reason, the angle θ formed by the first gas line 14 and the second gas line 15 is selected to be 10 ° to 90 °, and in this embodiment, the angle θ is selected to be 30 °, for example.
[0053]
In addition, the group V element gas is NH._ThreeThis NH_ThreeReduces the crystal growth efficiency by causing an addition reaction with trimethylgallium (TMG), trimethylaluminum (TMA), or the like._Three)₂Ga (CH_Three)₂In order to prevent the formation of solids such as, the distance from the point where the group III element source gas and the group V element source gas merge to the susceptor 7 is selected to be 2 to 15 cm, preferably 2 to 10 cm. In this embodiment, for example, 4 cm is selected.
[0054]
Further, the third gas line 16 and the fourth gas line 17 through which the dummy gas flows are configured to merge, for example, below the susceptor 7 in the outer peripheral portion of the horizontal flow path, and the susceptor 7 of the gas passage wall 13 is formed. The surface facing the surface, that is, the surface facing the susceptor 7 is inclined so that its cross-sectional area decreases toward the downstream side of the gas line.
[0055]
Here, the reason why the dummy gas is introduced into the third gas line 16 and the fourth gas line 17 is as follows. That is, the opposing surface of the susceptor 7 is heated by the radiant heat of the heated susceptor 7, but when the group III element and the group V element are grown on the growth surface of the substrate 8 placed on the susceptor 7, the III When a group element or group V element source gas comes into contact with the opposing surface of the susceptor 7, the group III element or group V element material is decomposed and deposited on the opposing surface, and the source material is wasted. This is to prevent this from happening. Further, for example, when measuring the temperature around the susceptor 7, a thermometer is installed on the portion of the facing surface, and if the raw material decomposes and precipitates on the facing surface of the susceptor 7, the temperature measurement is hindered. This is to prevent this. A dummy gas such as an inert gas is allowed to flow through the third gas line 16 and the fourth gas line 17 so as to prevent contact between the source gas and the opposing surface of the susceptor 7. The source gas can be flowed, and the crystal growth rate can be increased without increasing the supply amount of the source material.
[0056]
In addition to preventing the contact between the source gas and the opposing surface of the susceptor 7, there are the following reasons for flowing the dummy gas. That is, generally, the flow velocity of the source gas that flows radially below the susceptor 7 decreases as it goes downstream, but the thickness of the concentration boundary layer of the source gas that flows radially increases as the flow velocity decreases, and the growth surface of the substrate 8 increases. This is to prevent this because the crystal growth rate decreases further downstream of the source gas. Specifically, as described above, the facing surface of the susceptor 7 is inclined with respect to the susceptor 7, and the raw material gas is compressed by flowing a dummy gas in the vicinity of the facing surface, and the channel cross-sectional area becomes smaller toward the downstream. Then, by increasing the gas flow rate toward the downstream side, the growth rate is prevented from decreasing and the growth rate on the growth surface of the substrate 8 is made uniform.
[0057]
Further, the dummy gas is caused to flow through the two gas lines of the third gas line 16 and the fourth gas line 17 because the dummy gas flowing through the third gas line 17 and the fourth gas line 17 is as follows. Because it plays a role. That is, the dummy gas flowing in the fourth gas line 17 out of the two gas lines flows while contacting the opposing surface of the susceptor 7 and plays a role of maintaining the overall gas flow rate. Therefore, the dummy gas flowing through the fourth gas line 17 is mainly N, for example.₂An inert gas such as a gas is used. On the other hand, the dummy gas flowing in the third gas line 16 flows in substantially parallel with the source gas, and a part thereof may be mixed with the source gas, so that the gas composition is optimal for the source gas. That is, the composition of the dummy gas flowing through the third gas line 16 is, for example, HH when an AlGaN layer is grown on the growth surface of the substrate 8.₂When a GaInN layer is grown, N₂The composition is mainly composed of In this way, the composition of the dummy gas flowing through the third gas line 16 is optimized by the compound semiconductor grown on the growth surface of the substrate 8. Then, the dummy gas is caused to flow through the two gas lines, and only the composition of the dummy gas flowing in one gas line is changed by the compound semiconductor to be grown, so that the crystal to be grown can be grown only by changing the composition in one line. A suitable dummy gas can be supplied. Therefore, it is not necessary to replace all dummy gases each time a different crystal is grown, and fluctuations in the supply pressure of the primary piping due to the replacement of the dummy gas can be reduced, greatly increasing the burden on the flow control of each gas line. Can be reduced.
[0058]
The rotational drive system 3 and the susceptor / rotating annular plate 4 are for revolving and rotating the susceptor 7, and in this embodiment, are configured as shown in FIG. FIG. 5 is a cross-sectional view and a plan view showing the susceptor 7 according to this embodiment.
[0059]
As shown in FIG. 4, the rotation drive system 3 and the susceptor / rotation ring plate 4 are made of a material having a thermal insulation property that does not absorb visible light and near infrared rays, for example, an annular rotation ring plate 20 made of quartz. It is configured to be rotatable around a central axis OO. In addition, a plurality of circular openings 20a for mounting the plurality of susceptors 7 are provided on the concentric circumference of the rotating annular plate 20, and the plurality of susceptors 7 can be attached to and detached from these openings 20a. And it mounts rotatably with respect to these openings 20a. Further, by holding the susceptor 7 in these openings 20a, the lower surfaces of the susceptor 7 and the rotating annular plate 20 constitute a smooth surface of the gas passage wall 9, and a gas such as a source gas or a dummy gas flows. In some cases, it plays a role in regulating the flow of gas. Here, as an example of the dimensions of the rotating annular plate 20, the thickness of the rotating annular plate 20 is 6 mm and the radius is 260 mm. Further, a circular opening 20a having a diameter of 63 mm is formed such that the center thereof is overlapped on a circumference having a radius of 190 mm with the central axis OO of the rotating annular plate 20 as the center.
[0060]
As shown in FIG. 5A, the susceptor 7 includes a substrate holding unit 7a and a substrate heating unit 7b, which are each formed of, for example, SiC. As shown in FIG. 5B, the substrate holding portion 7a has an annular shape provided with an opening 7c corresponding to the shape of the substrate 8 and the shape of the substrate heating portion 7b. In addition, hooks 7d to 7f protruding from the opening 7c are provided at, for example, three portions below the substrate holding portion 7a. These hooks 7d to 7f are, for example, 0.5 mm in thickness, 2 mm in width, and 1 mm in length with respect to the radial direction of the substrate holding portion 7a. And these hooks 7d-7f are comprised so that the board | substrate 8 and the board | substrate heating part 7b may be hold | maintained in the position of the opening 7c. That is, when holding the substrate 8 on the susceptor 7, the substrate 8 with the growth surface facing downward is dropped into the opening 7c from above the substrate holding portion 7a and held by the hooks 7d to 7f, and then the substrate heating portion 7b. Is placed on the substrate 8. The substrate heating unit 7b is pressed against the substrate 8 by its own weight. Therefore, by heating the substrate heating unit 7b, heat is conducted from the substrate heating unit 7b to the substrate 8, and the substrate 8 can be heated. Further, when taking out the substrate 8 from the susceptor 7, for example, using vacuum tweezers, the substrate heating unit 7 b is sucked and taken out, and then the substrate 8 is sucked and taken out.
[0061]
Further, as shown in FIG. 6, an annular rotation ring 21 fixed to a horizontal MOCVD apparatus and having a gear 21a on the inner periphery is provided on the outer side of the rotating annular plate 20, and provided on the outer periphery of the susceptor 7. The susceptor 7 is configured to be able to rotate by meshing with the gear 7g. Then, when the rotating annular plate 20 is rotated around its central axis OO by the rotation drive system 3, the susceptor 7 revolves around the central axis OO of the rotating annular plate 20 and the susceptor 7 itself. Rotate around the center axis of the.
[0062]
As described above, since the substrate 8 with the growth surface facing downward is placed on the susceptor 7, for example, screws and pins are not used to hold the substrate 8 on the susceptor 7. In addition to preventing gas turbulence and shadow effects due to protrusions such as screws and pins, it is possible to simplify the attachment and removal of the substrate 8 from the susceptor 7, thereby preventing contamination of the substrate 8. be able to.
[0063]
Next, as shown in FIG. 7, the heating device 6 includes an annular quartz tube lamp 30 as a light source, and an annular lamp house 31 for condensing infrared rays emitted from the quartz tube lamp 30 onto the susceptor 7. Are configured with their central axes in common. Here, the shape of the cross section in the radial direction of the annular lamp house 31 is, for example, a parabola, and the annular quartz tube lamp 30 is provided at the focal point of the parabola. Further, the inner peripheral surface of the lamp house 31 is a light reflecting surface, and the infrared rays emitted from the quartz tube lamp 30 are reflected by the light reflecting surface and traveled in parallel with the central axis OO to be condensed on the susceptor 7. Is configured to do. Here, the susceptor 7 is placed on the opening 20 a of the rotating annular plate 20 via a light passage plate 5 a that passes light below the heating device 6. The heating system 6 and the reaction system in which the susceptor 7 located below is spatially partitioned and separated by a light passage plate 5a. The light passage plate 5a is an annular quartz plate corresponding to the shape of the heating device 6 and having a width slightly larger than the diameter of the susceptor 7, and constitutes a part of the top plate 5 in the horizontal MOCVD apparatus. On the rotating annular plate 20, two cylinders 32 and 33 made of, for example, molybdenum (Mo) having different radii overlap with the central axis OO of the rotating annular plate 20 in the radial direction. It is provided so as to sandwich the susceptor 7. Light reflecting films 32 a and 33 a made of, for example, an Au film for reflecting infrared rays from the heating device 6 toward the susceptor 7 are provided on the surfaces of the two cylinders 32 and 33 on the susceptor 7 side. Thereby, since the infrared rays irradiated to the two cylinders 32 and 33 are reflected toward the susceptor 7, most of the infrared rays emitted from the quartz tube lamp 30 are effectively irradiated to the susceptor 7. The uniformity and efficiency of heating can be improved.
[0064]
In addition, the space partitioned by the susceptor 7 and the light passage plate 5a is configured to be filled with an inert gas, and an inert gas is introduced to blow the inert gas onto the lower surface of the light passage plate 5a. A tube (not shown) is provided. This is because gas flowing below the susceptor 7 may leak upward from the susceptor 7 through the gap between the sliding surfaces of the susceptor 7 and the rotating annular plate 20 during crystal growth. This leaked gas adheres to the light passage plate 5a and becomes cloudy, reducing the amount of light transmitted through the light passage plate 5a, and thus preventing this. That is, by blowing an inert gas onto the lower surface of the light passage plate 5a through the inert gas introduction pipe, the light passage plate 5a is prevented from being fogged and a certain amount of infrared rays from the heating device 6 is maintained. .
[0065]
As shown in FIG. 8, the gas discharge unit 2 includes an exhaust gas constriction 40, an exhaust gas reservoir 41, and a plurality of exhaust gas pipes 42. The exhaust gas constriction portion 40 and the exhaust gas reservoir portion 41 are provided on the circumference concentric with the rotating annular plate 20 in the downstream portion of the susceptor 7. The plurality of exhaust gas pipes 42 are arranged at equal intervals on the circumference concentric with the rotating annular plate 20 outside the exhaust gas reservoir 41 and connected to the exhaust gas reservoir 41. Here, for example, the exhaust gas constriction 40 is composed of a mesh-like thin plate 40a and grooves 40b made of a metal such as stainless steel and provided with a large number of minute holes. Here, the diameter of one minute hole provided in the mesh-like thin plate 40a is, for example, 0.3 mm, and the surface density is, for example, 1 / mm.²It is. The dimension of the groove 40b is 5 × 5 mm, for example.
[0066]
The exhaust gas constriction portion 40 is provided because the susceptor 7 in the portion (downstream) close to the flow velocity of the gas below the susceptor 7 in the portion (upstream) far from the exhaust gas pipe 42 when the gas flows. This is to prevent the gas flow velocity on the growth surface of the substrate 8 from becoming non-uniform due to the increase in the gas flow velocity below. Further, by providing the exhaust gas constriction 40 in this way, the pressure of the exhaust gas can be made uniform over the circumferential direction of the exhaust gas constriction 40. Therefore, the gas discharge can be made uniform in every part of the substrate 8, and the gas flow rate can be made uniform on the growth surface of every substrate 8, so that the uniformity of crystal growth can be improved. Further, by providing the exhaust gas reservoir 41 on the circumference, the number of exhaust gas pipes 42 connected to the exhaust gas reservoir 41 can be reduced.
[0067]
As shown in FIG. 9, the top plate 5 includes a disk 5b made of a metal such as stainless steel, an annular light passage plate 5a provided on the outer periphery of the disk 5b, and a light passage plate 5a. It is comprised from the annular | circular shaped metal plate 5c which consists of stainless steel provided in the outer periphery, for example. As described above, the light passage plate 5a is configured in a shape corresponding to the shape of the heating device 6 so as to pass infrared rays emitted from the heating device 6 (not shown) provided above. The top plate 5 is supported by the top plate support 50 at the center of the disk 5b, and thereby the vertical position of the top plate 5 is fixed. In addition, since the rotary ring plate 20 and the susceptor 7 are configured to be rotatable by the rotation drive system 3, in order to prevent the rotational movement from being transmitted to the top plate 5, the top plate support 50 has a bearing. (Not shown) is provided.
[0068]
When removing the substrate 8 from the susceptor 7, first, both the quartz tube lamp 30 and the top plate 5 of the heating device 6 are pulled upward. Next, using vacuum tweezers (not shown), the substrate heating unit 7b is sucked and taken out, and then the substrate 8 is sucked and taken out.
[0069]
As described above, the top plate 5 is composed of the disk 5b made of, for example, stainless steel, the metal plate 5c, and the light passage plate 5a made of quartz, and is provided by the top plate support 50 provided on the central axis of the horizontal MOCVD apparatus. By being supported, sufficient mechanical strength can be obtained even when pressure is applied to the top plate 5 due to the reduced pressure of the reaction part in the horizontal MOCVD apparatus.
[0070]
Next, a method for growing GaN on the growth surface of the substrate 8 in the horizontal MOCVD apparatus according to the embodiment configured as described above will be described.
[0071]
  NowHeavenWith the plate 5 and the heating device 6 removed from the horizontal MOCVD apparatus, a plurality of substrates 8 are placed on each susceptor 7 arranged at a predetermined position by the method described above. In this state, the space between the susceptor 7 and the top plate 5 is N₂Filled with inert gas such as gas. Next, after covering the top plate 5 together with the heating device 6, power is transmitted to the rotational drive system 3 by a predetermined method, and the rotating annular plate 20 is rotated at a predetermined rotational speed. As a result, the plurality of susceptors 7 revolve and rotate around their own central axis. Further, the susceptor 7 is heated to a predetermined temperature by the heating device 6.
[0072]
Next, as shown in FIG. 2, for example, N as a dummy gas (carrier gas) is supplied to the third gas line 16 through a gas inflow terminal (not shown).₂Gas and H₂A mixed gas with the gas is introduced and, for example, N is used as a dummy gas in the fourth gas line 17.₂After introducing the gas inert gas, similarly, for example, TMG (Ga (CH_Three)_Three), And as the N raw material in the second gas line 15, for example, NH_ThreeIntroduce raw material gas containing. Here, the dummy gas introduced into the third gas line 16 has the optimal dummy gas composition for crystal growth of GaN. These source gas and dummy gas uniformly flow radially through the horizontal flow paths of the first gas line 14 to the fourth gas line 17, pass through the gas constrictions 10 a to 13 a, respectively, and then upstream of the susceptor 7. The group III element source gas and the group V element source gas join at an angle of, for example, 30 °. Next, the raw material gas that has flowed into the first gas line 14 and the second gas line 15 below the susceptor 7 flows into the third gas line 16 and the fourth gas line 17. The dummy gas is merged almost in parallel. As a result, TMG and NH are formed below the susceptor 7._ThreeAnd GaN are grown on the growth surface of each substrate 8 placed on each susceptor 7. Then, as shown in FIG. 8, the exhaust gas composed of the raw material gas containing the materials and reaction products not deposited on the growth surface on the substrate 8 and the dummy gas passes through the exhaust gas constriction 40 and temporarily After being stored in the exhaust gas reservoir 41, the exhaust gas is exhausted to the outside through the exhaust gas pipe 42.
[0073]
After the GaN crystal growth is completed, the introduction of the source gas and the dummy gas is stopped while the heating by the heating device 6 is stopped, and then the rotation of the rotating annular plate 20 is stopped. Next, after the top plate 5 and the heating device 6 are both lifted upward and removed from the horizontal MOCVD apparatus, the substrate 8 after completion of crystal growth is sucked out from the susceptor 7 using a plurality of vacuum tweezers, for example.
[0074]
In the above description, the GaN crystal is grown on the substrate 8. However, the group III element source gas and the group V element source gas can be arbitrarily changed depending on the compound semiconductor grown on the substrate 8. The dummy gas introduced into the gas line is changed to an optimum gas for the source gas of these group III elements and group V elements. Here, the dummy gas introduced into the fourth gas line is always an inert gas.
[0075]
As described above, according to this embodiment, it is possible to easily set an optimum gas composition and optimum growth conditions for growing a homogeneous crystal uniformly on the growth surface of the substrate 8. A horizontal MOCVD apparatus corresponding to the substrate can be obtained.
[0076]
Although one embodiment of the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible.
[0077]
For example, the numerical values, materials, and structures listed in the above-described embodiment are merely examples, and different numerical values, materials, and structures may be used as necessary.
[0078]
Specifically, for example, in the above-described embodiment, the gas constriction portions 10a to 13a are provided separately from each other along the circumferential direction. As the structure of the gas constriction portions 10a to 13a, slits are provided. Or a sintered body of fine particles may be used. Further, for example, in the above-described embodiment, the gas inflow terminals are attached to the side surfaces of the cylindrical portions of the gas passage walls 10 to 13, and the source gas and the dummy gas are supplied to the first gas lines 14 to through the gas inflow terminals. Although it introduces into the 4th gas line 17, it connects so that a pipe etc. may be directly connected to the horizontal flow path of each 1st gas line 11-4th gas line 14, and it may introduce source gas and dummy gas. In this case, the gas constriction portions 10a to 13a can be optimized and designed so that the source gas and the dummy gas flow more uniformly and radially in the horizontal flow path.
[0079]
For example, in the above-described embodiment, the susceptor 7 is made of SiC, but may be made of carbon coated with SiC.
[0080]
Further, for example, in the above-described embodiment, an annular rotation ring 21 for rotating the susceptor 7 fixed to the horizontal MOCVD apparatus is provided on the outer periphery of the rotating annular plate 20, and the gear 21a is provided. Although provided on the inner periphery of the rotation ring 21, a disk provided with a gear on the outer periphery for rotating the susceptor 7 may be provided on the inner periphery of the rotating annular plate 20. In this case, the susceptor 7 can be rotated by moving the susceptor 7 along the outer periphery of the disk while meshing the gear 7g provided on the outer periphery of the susceptor 7 and the gear provided on the outer periphery of the disk. it can. Further, for example, in the above-described embodiment, the gear 7g and the gear 21a are directly meshed with each other. However, a third gear is provided between the gear 7g and the gear 21a, and the gear 7g and the gear 21a are connected to each other. In this case, the susceptor 7 can be rotated by rotating the rotating annular plate 20. Further, for example, in the above-described embodiment, as a driving method for rotating the rotating annular plate 20, a method of transmitting power to the rotational drive system 3 in the inner peripheral portion of the rotating annular plate 20 is adopted. It is also possible to adopt a method of transmitting power to the outer periphery of the rotating annular plate 20 and rotating it.
[0081]
Further, for example, in the above-described embodiment, the shape of the cross section of the light reflecting surface in the radial direction of the lamp house 31 is a parabola, but the shape of the cross section may be an ellipse instead of a parabola. In this case, the annular quartz tube lamp 30 is provided at one focal point of the ellipse, and the other focal point is located at a position several cm above the susceptor 7. Also by this, the several susceptor 7 arrange | positioned on the periphery can be heated uniformly. Moreover, it is also possible to install a light reflecting plate on the rotating annular plate 20, and by doing so, it is possible to further increase the heating efficiency when heating the susceptor.
[0082]
Further, for example, in the above-described embodiment, a plurality of holes are provided on the circumference concentric with the exhaust gas constriction portion 40 between the groove 40 b portion of the exhaust gas constriction portion 40 and the exhaust gas reservoir portion 41. May be provided side by side at equal intervals. At this time, the diameter of the hole is set to 20 mm, for example, and the interval between the plurality of holes is set to 40 mm, for example.
[0083]
【The invention's effect】
As described above, according to the first aspect of the present invention, since the gas constriction is provided in the passage through which the reaction gas flows, the reaction gas can be made to flow uniformly on the growth surface of the substrate. A homogeneous crystal can be grown on the film with a uniform film thickness.
[0084]
According to the second aspect of the present invention, the annular rotating plate having heat insulation provided with a plurality of openings for installing the susceptor constitutes a part of the passage wall of the gas passage. This makes it possible to grow a uniform crystal with a uniform film thickness on the growth surface of the substrate.
[0085]
According to the third aspect of the present invention, the susceptor includes the substrate holding portion that holds one substrate and the substrate heating portion that transfers heat to the substrate to heat it, so that only the substrate is provided. Can be heated, so that the thermal efficiency can be improved and the growth cost can be reduced.
[0086]
According to the fourth aspect of the present invention, the heating means includes an annular light source and an annular reflector for condensing the light emitted from the light source on the susceptor. Since only this can be heated, the thermal efficiency in heating the susceptor can be improved.
[0087]
According to the fifth aspect of the present invention, since the gas exhaust means has the exhaust gas constriction, the gas flow velocity can be made uniform over the growth surface of any substrate, Crystals can be grown uniformly on the growth surface.
[0088]
Further, according to the sixth aspect of the present invention, by having the top plate that can be attached and detached and the top plate support means for supporting the top plate, the substrate can be attached to and removed from the susceptor. While taking out can be performed easily, the mechanical strength of the top plate can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the configuration of a horizontal MOCVD apparatus according to an embodiment of the present invention.
FIG. 2 is a radial cross-sectional view showing a gas line / gas supply system according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view along the circumferential direction of a gas constriction according to an embodiment of the present invention.
FIG. 4 is a cross-sectional view showing a rotating annular plate provided with a susceptor according to an embodiment of the present invention.
FIG. 5 is a plan view and a cross-sectional view showing a susceptor according to an embodiment of the present invention.
FIG. 6 is a plan view showing a susceptor and a rotation ring according to an embodiment of the present invention.
FIG. 7 is a cross-sectional view showing a heating device according to an embodiment of the present invention.
FIG. 8 is a cross-sectional view of a gas discharge unit according to an embodiment of the present invention.
FIG. 9 is a cross-sectional view showing a top plate according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Gas line / gas supply system, 2 ... Gas discharge part, 3 ... Rotary drive system, 4 ... Susceptor / rotary ring plate, 5 ... Top plate, 6 ... Heating Device, 7 ... Susceptor, 8 ... Substrate, 20 ... Rotating circular plate

Claims (10)

A plurality of susceptors disposed on one circumference and having a substrate disposed with a growth surface facing downward ;
A plurality of gas passages for supplying reaction gas toward the susceptor;
In a chemical vapor deposition apparatus having a heating means for heating the susceptor,
In the plurality of gas passages, a plurality of gas passage walls including a cylindrical portion and a brim-shaped flat plate portion on the cylindrical portion are arranged at intervals with the central axis of the circumference in common, and a space portion therebetween And a horizontal flow path is constituted by a space portion between the flat plate portions of the plurality of gas passage walls,
The plurality of gas passages define a flow of the reaction gas to the susceptor, and a gas constriction is formed on the flat plate portion of the gas passage wall of the plurality of gas passages on a circumference concentric with the circumference. Part is provided ,
The outermost gas passage wall of the plurality of gas passage walls extends to the outside of the susceptor, and the cross-sectional area of the flow path between the gas passage wall and the susceptor extends from the upstream side to the downstream side. Configured to decrease,
A chemical vapor deposition apparatus characterized in that an outermost gas passage and a gas passage immediately inside the plurality of gas passages each constitute a gas passage for dummy gas . The plurality of gas passages include a first gas passage for a Group III element source gas and a second gas passage for a Group V element source gas, and the first gas passage and the second gas passage. 2. The chemical vapor deposition apparatus according to claim 1, wherein the two are joined at an angle downstream of the gas constriction portion. The chemical vapor deposition apparatus according to claim 2, wherein the angle is 10 ° or more and 90 ° or less. A plurality of susceptors disposed on one circumference and having a substrate disposed with a growth surface facing downward;
A plurality of gas passages for supplying a reactive gas toward the susceptor;
In a chemical vapor deposition apparatus having a heating means for heating the susceptor,
In the plurality of gas passages, a plurality of gas passage walls formed of a cylindrical portion and a flange-shaped flat plate portion on the cylindrical portion are arranged at intervals with the central axis of the circumference in common, and a space portion therebetween And a horizontal flow path is constituted by a space portion between the flat plate portions of the plurality of gas passage walls,
The plurality of gas passages define a flow of the reaction gas to the susceptor, and an annular rotating plate provided with a plurality of openings for installing the susceptor is formed of the plurality of gas passages. Constitute part of the gas passage wall of the innermost gas passage,
The outermost gas passage wall of the plurality of gas passage walls extends to the outside of the susceptor, and the cross-sectional area of the flow path between the gas passage wall and the susceptor extends from the upstream side to the downstream side. Configured to decrease,
The outermost gas passage and the immediately inner gas passage of the plurality of gas passages constitute gas passages for dummy gas, respectively.
A chemical vapor deposition apparatus characterized by that. 5. The chemical vapor deposition apparatus according to claim 4, wherein when the susceptor is installed in the opening of the rotating plate, a lower surface of the susceptor constitutes a part of the gas passage wall. 5. The chemical vapor deposition apparatus according to claim 4, wherein the susceptor is configured to revolve by rotation of the rotating plate. The susceptor has a first gear on an outer peripheral portion, and the first gear is connected to a second gear fixed to the chemical vapor deposition apparatus, and the first plate is rotated by the rotation of the rotating plate. 5. The chemical vapor deposition apparatus according to claim 4, wherein the susceptor is configured to rotate by rotation of one gear. 8. The chemical vapor deposition apparatus according to claim 7, wherein the second gear is provided on an inner periphery of the annular plate. 8. The chemical vapor deposition apparatus according to claim 7, wherein the second gear is provided on an outer peripheral portion of a circular plate. 5. The chemical vapor deposition apparatus according to claim 4, wherein the lower surface of the rotating plate and the lower surface of the susceptor are substantially coplanar.

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