JP2008053636A - Vapor deposition system, and compound semiconductor film and growth method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vapor deposition system which has high availability efficiency for a material gas and can inhibit the introduction of defects into a grown film, a compound semiconductor film which has only a few defects, and its growth method. <P>SOLUTION: In the vapor deposition system 10, a material gas G2, supplied from a second feed inlet 30 flows close to a first feed inlet 28 without residence by a gas flow adjuster 32 and reacts with a material gas G1. As a result, the material gas G1 and the material gas G2 react with a substrate W each other. That is, in the vapor deposition system 10, improvement in the availability efficiency of the material gases G1, G2 can be carried out. Moreover, since the film formation is less apt to be held at positions other than on the substrate W, the situation where defects are introduced into the compound semiconductor film M is controlled significantly. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vapor phase growth apparatus, a compound semiconductor film, and a growth method thereof.

  Compound semiconductors such as aluminum nitride (AlN), gallium nitride (GaN), gallium arsenide (GaAs), and indium phosphide (InP) are suitably used for light-emitting elements and high-speed electronic devices. A crystal made of such a compound semiconductor is usually grown on a substrate using a metal organic chemical vapor deposition method (MOCVD method) or a hydride vapor phase epitaxy method (HVPE method). In particular, when the HVPE method is used, these single crystals can be grown at a high speed.

Examples of the vapor phase growth apparatus for performing the HVPE method include those described in Non-Patent Document 1. Such a vapor phase growth apparatus is also used when growing an AlN single crystal. An NH ₃ gas introduction tube for introducing ammonia (NH ₃ ) into the reaction tube, and aluminum trichloride (AlCl ₃ ) in the reaction tube. An AlCl ₃ gas introduction pipe to be introduced and a substrate support are provided. The growth of AlN using such a vapor phase growth apparatus is performed by the following procedure.
(1) Carrier gas (hydrogen gas, nitrogen gas) is introduced into the reaction tube, and the temperature is raised until the substrate support is about 1200 ° C.
(2) NH ₃ NH ₃ was introduced from the gas inlet, the temperature of the substrate support is held to stabilize.
(3) Introduce AlCl ₃ from the AlCl ₃ gas introduction tube and grow the AlN crystal film on the substrate until it reaches a predetermined thickness. At this time, NH ₃ and AlCl ₃ react on the substrate in the reaction tube to grow an AlN film.
(4) When the AlN film reaches a predetermined thickness, the introduction of AlCl ₃ is stopped, the carrier gas is allowed to flow, the heater is stopped, and the temperature of the reaction tube is lowered to room temperature. When the temperature is sufficiently lowered, the substrate on which the AlN film has grown on the surface inside the container is taken out.
T.A. Goto et al., JOURNAL OF MATERIAL SCIENCE 27 (1992) p. 247

However, in the above-described vapor phase growth apparatus, the reaction between NH ₃ and AlCl ₃ is likely to occur in places other than the substrate, such as near the inner wall of the reaction tube or the jet outlet of the gas supply tube, and the efficiency is increased on the substrate. The AlN film could not be grown well. In addition, the AlN film grown at a place other than on the substrate is likely to peel off and adhere to the substrate. In this case, there is a problem that defects are introduced into the AlN film.

  The present invention has been made in view of the above circumstances, a vapor phase growth apparatus capable of suppressing the introduction of defects into a growth film with high utilization efficiency of a source gas, a compound semiconductor film with few defects, and a growth method therefor The purpose is to provide.

  In order to solve the above-described problems, a vapor phase growth apparatus according to the present invention is inserted into a reaction tube for growing a compound semiconductor by mixing a first source gas and a second source gas, and the reaction tube. A first supply tube for supplying the first source gas into the reaction tube, a second supply tube connected to the reaction tube and supplying the second source gas into the reaction tube, A substrate holder for holding a substrate near a first supply port formed at an end located in the reaction tube of the one supply tube, and a portion where the outer wall of the first supply tube faces the inner wall of the reaction tube The first supply pipe and the reaction tube form a double tube structure, and the space formed between the outer wall of the first supply pipe and the inner wall of the reaction tube is the second raw material. A second supply pipe is connected to the reaction tube so as to be a gas flow path, and is located in the reaction tube of the first supply pipe. At the end, the gas flow adjusting portion bulging toward the inner wall of the reaction tube so as to reduce the cross-sectional area of the flow path of the second raw material gas.

  In the vapor phase growth apparatus of the present invention, the gas flow adjusting unit causes the second source gas supplied from the second supply pipe to flow to the vicinity of the first supply port of the first supply pipe without stagnation. Reacts with the first source gas. Therefore, most of the first source gas and the second source gas react on the substrate held by the substrate holder near the first supply port of the first supply pipe. Therefore, the utilization efficiency of the source gas is increased. In addition, if there is a lot of film deposition on the wall other than the substrate surface such as the inner wall of the reaction tube, these films will become thick during the growth, float on the substrate surface, fall down, and defects may be introduced into the growth film. Although it may occur, in the vapor phase growth apparatus of the present invention, it is difficult for the film to grow on the inner wall of the reaction tube. For this reason, the introduction of defects into the growth film is also significantly suppressed.

  In addition, the gas flow adjusting unit is located on the first supply port side from the first portion, and the outer periphery extends toward the first supply port. It is preferable to have the 2nd part which narrows. In this case, the second source gas flows without generating vortices in the space formed between the outer wall of the first supply pipe and the inner wall of the reaction pipe, and the downstream flow is not disturbed.

  The vapor phase growth apparatus is further inserted into the first supply pipe, and further includes a third supply pipe for flowing the first source gas, the first supply pipe, the third supply pipe, Form a double tube structure, and a space for supplying a gas that does not react with the first and second source gases into the reaction tube includes an outer wall of the third supply tube and an inner wall of the first supply tube. It is preferable that it is formed between. In this case, due to the presence of the gas that does not react with the first and second source gases, the first source gas and the second source gas react at the position of the first supply port of the first supply pipe. Therefore, the utilization efficiency of the raw material gas is further improved.

  The compound semiconductor film of the present invention is grown using the vapor phase growth apparatus of the present invention. Since the use of the vapor phase growth apparatus of the present invention can suppress the introduction of defects into the growth film, a compound semiconductor film with few defects can be obtained. Therefore, the formation of defects in the structure of a semiconductor element manufactured using the same is suppressed, and the occurrence of malfunction of the element is reduced. The “compound semiconductor film” in the present invention includes, in addition to the compound semiconductor film formed on the substrate, a compound semiconductor film cut out by thick bulk growth (for example, a semiconductor substrate). And

  In the compound semiconductor film growth method of the present invention, the compound semiconductor film is grown using the vapor phase growth apparatus of the present invention. In this growth method, since the vapor phase growth apparatus of the present invention is used, the utilization efficiency of the source gas is increased and the introduction of defects into the growth film is suppressed.

  According to the present invention, there are provided a vapor phase growth apparatus, a compound semiconductor film with few defects, and a growth method therefor, which have high utilization efficiency of source gas and can suppress introduction of defects into a growth film.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicate descriptions are omitted.

(First embodiment)
FIG. 1 is a diagram schematically showing a vapor phase growth apparatus according to the first embodiment. The vapor phase growth apparatus 10 shown in FIG. 1 is preferably a hydride vapor phase growth apparatus (HVPE apparatus), but may be a metal organic vapor phase growth apparatus (MOCVD apparatus). When the vapor phase growth apparatus 10 is an HVPE apparatus, a compound semiconductor can be grown at a high speed. As compound semiconductors to be grown, there are III-V compound semiconductors (for example, GaAs, InP, AlN, GaN, InN, AlGaN, InGaN, AlInGaN, etc.) and II-VI group compound semiconductors (ZnSe, ZnO, etc.).

The vapor phase growth apparatus 10 includes a substantially cylindrical reaction tube 12 for growing a compound semiconductor by mixing a first source gas G1 and a second source gas G2. The source gases G1 and G2 are appropriately selected according to the generated compound semiconductor. The source gas G1 preferably contains a group III element such as Ga, Al, In or the like, and the source gas G2 preferably contains a group V element such as As, P or N. These source gases G1 and G2 may be diluted with a carrier gas such as hydrogen (H ₂ ), nitrogen (N ₂ ), or argon (Ar) in order to adjust the gas flow rate. In one embodiment, the source gas G1 is H ₂ diluted AlCl ₃ and the source gas G2 is H ₂ diluted NH ₃ . In this case, an AlN single crystal is grown as a compound semiconductor by mixing the source gas G1 and the source gas G2.

  At one end (upstream end) 12 a of the reaction tube 12, a first supply tube 24 for supplying the source gas G 1 into the reaction tube 12 and a source gas G 2 for supplying the source gas G 2 into the reaction tube 12 are provided. A second supply pipe 16 is attached. The supply pipes 16 and 24 are connected to the reaction pipe 12.

  A substrate holder 14 that holds the substrate W horizontally in the reaction tube 12 is attached to the other end (downstream end) 12 b of the reaction tube 12. The substrate holder 14 holds the substrate W in the vicinity of the first supply port 28 formed at the end portion 26 located in the reaction tube 12 in the supply tube 24. The substrate W is accommodated in the reaction tube 12 and is, for example, a semiconductor substrate such as a silicon (Si) substrate, a sapphire substrate, a silicon carbide (SiC) substrate, a zinc oxide (ZnO) substrate, or a GaAs substrate. In FIG. 1, one substrate W is disposed as an example, but a plurality of substrates W may be disposed. In this case, the plurality of substrates W are respectively fixed to the plurality of substrate holders 14, and each substrate holder 14 is fixed to the inner surface of the reaction tube 12. The substrate holder 14 is preferably arranged in a circular shape so as to surround the tube axis of the reaction tube 12. In such an arrangement, the difference in growth rate between the substrates is small, and a uniform film is easily formed on all the substrates. When a plurality of substrates W are arranged, the compound semiconductor film M (compound semiconductor) can be grown on each substrate W at the same time, so that productivity is further improved. Further, if a rotation mechanism is attached to the substrate holder 14 and the substrate is rotated during growth, the uniformity of the growth rate on the substrate surface is improved. When the mixed gas G4 of the source gas G1 and the source gas G2 reaches the substrate W, the compound semiconductor film M is grown on the substrate W. At the other end 12 b of the reaction tube 12, an exhaust port 40 located on the downstream side of the substrate W is formed.

  One end 25 of the supply pipe 24 is connected to a supply device 23 that generates the raw material gas G1. The other end 26 of the supply tube 24 is located in the reaction tube 12. The supply pipe 24 has an end portion 26 in which a first supply port 28 for supplying the source gas G <b> 1 into the reaction tube 12 is formed, and an end portion 25 located on the upstream side of the end portion 26. The inner shape of the supply pipe 24 is a substantially straight tubular shape from the end portion 26 to the end portion 25, and the flow passage cross-sectional area hardly changes. The supply tube 24 is inserted into the reaction tube 12 and forms a double tube structure with the reaction tube 12. That is, since the outer wall of the supply tube 24 has a portion facing the inner wall of the reaction tube 12, the reaction tube 12 and the supply tube 24 form a double tube structure. A substrate holder 14 holding the substrate W is disposed near the supply port at a position downstream of the supply port 28. In order to obtain a high growth rate on the substrate W, the distance between the supply port 28 and the substrate W (distance between the supply port 28 and the center point of the surface of the substrate W in the tube axis direction of the reaction tube 12) d1 It is preferably 0.2 to 5 times the diameter L of 12 (see FIG. 2).

The source gas G1 may be supplied by evaporating solid AlCl ₃ outside the reaction tube 12 to obtain an AlCl ₃ gas, and then introducing the AlCl ₃ gas into the reaction tube 12 or by providing a separate heater 22a. You may install the source boat which accommodated raw materials, such as Al pellet, in the production | generation pipe | tube 21. FIG. In the production tube 21, for example, a source boat 20 in which Al pellets are accommodated is installed. A gas G3 is introduced into the generation pipe 21 via the introduction pipe 18. When the gas G3 comes into contact with the Al pellets in the source boat 20 in the generation pipe 21, the source gas G1 is generated. For example, when hydrogen chloride (HCl) diluted with H ₂ is used as the gas G3 and Al pellets are stored in the source boat 20, AlCl ₃ diluted with H ₂ is generated as the source gas G1. Here, the production tube 21 is disposed outside the reaction tube 12, but a structure in which the production tube 21 is installed in the reaction tube 12 can also be adopted.

  The discharge port 29 of the supply pipe 16 is located upstream of the supply port 28 of the supply pipe 24. Therefore, the source gas G <b> 2 discharged from the discharge port 29 of the supply pipe 16 is supplied to the surface of the substrate W from between the end portion 26 of the supply pipe 24 and the reaction tube 12. That is, the supply pipe 16 is connected to the reaction pipe 12 so that a space SP formed between the outer wall of the supply pipe 24 and the inner wall of the reaction pipe 12 serves as a flow path for the source gas G2. Thus, a second supply port 30 for supplying the source gas G2 to the surface of the substrate W is formed between the end portion 26 of the supply tube 24 and the reaction tube 12. The supply port 30 surrounds the supply port 28 in an annular shape when viewed from the tube axis direction of the reaction tube 12.

  At the end portion 26 of the supply pipe 24, a gas flow adjusting portion 32 swelled outward is formed so as to narrow the cross section of the second supply port 30. That is, the gas flow adjusting unit 32 swells toward the inner wall of the reaction tube 12 in the vicinity of the supply port 28 of the supply tube 24 so as to reduce the cross-sectional area of the flow path of the source gas G2. The gas flow adjusting unit 32 has a first portion 32a having an outer periphery extending toward the supply port 28 (that is, toward a downstream side in a direction along the extending direction of the supply pipe), and an outer periphery toward the supply port 28. However, the second portion 32b may have either one of the first portion 32a and the second portion 32b. The second part 32b is located adjacent to the supply port 28 side from the first part 32a, and the gas flow adjusting part 32 as a whole has a spindle shape (or streamline). Therefore, the cross-sectional area of the flow path of the source gas G2 is once narrowed toward the downstream side at the position of the gas flow adjusting unit 32 and then widened thereafter. The second portion 32b has a flat tip surface 24a. In FIG. 1, the gas flow adjusting unit 32 has a cross-sectional shape formed in a straight line, but these may be curved, and the gas flow adjusting unit 32 may take a streamlined shape.

  Here, with reference to FIG. 2, these preferable shapes when the reaction tube 12, the gas flow adjusting unit 32, and the supply tube 24 are substantially rotationally symmetric will be described in detail. FIG. 2 is a diagram schematically showing the main part of the vapor phase growth apparatus shown in FIG. The diameter of the supply port 28 is x, the diameter of the reaction tube 12 is L, the shortest distance between the outer periphery of the gas flow adjusting unit 32 and the inner wall of the reaction tube 12 is d, and the gas flow adjusting unit 32 formed near the supply port 28. The length in the flow direction of the first portion 32a in which the outer diameter increases is y, the length in the flow direction of the first portion 32a in which the outer diameter widens is m, and the length in the flow direction of the second portion 32b whose outer diameter decreases toward the supply port 28. Let l be l. A preferable relationship between these sizes is as follows. d is preferably from x / 4 to 20x. y is preferably 0 or more and less than (Lx) / 2. l is preferably 0 or more and 20x or less. m is preferably 0 or more and 20x or less. However, at least one of l and m is not zero. x is preferably 0.001L or more and 0.5L or less.

  It is preferable that a heater 22 b extending along the tube axis direction of the reaction tube 12 is provided around the reaction tube 12. The heater 22b is located downstream of the heater 22a. The heater 22a heats the source boat 20 and promotes the generation of the source gas G1. The heater 22b heats the substrate W and promotes the reaction between the source gas G1 and the source gas G2. Moreover, it is preferable that the outer periphery of the heater 22a and the heater 22b is covered with a heat insulating material.

  Here, an example of a method for growing a compound semiconductor using the vapor phase growth apparatus 10 will be described. First, a carrier gas (hydrogen gas, nitrogen gas, etc.) is introduced into the reaction tube 12 and the temperature is raised until the substrate holder 14 reaches about 1100 ° C., for example. Next, the source gas G2 is supplied from the supply pipe 16 into the reaction pipe 12 to stabilize the temperature of the substrate holder 14. Further, the source gas G1 is supplied into the reaction tube 12 from the supply tube 24, and the compound semiconductor film M is grown on the substrate W until it reaches a predetermined thickness. At this time, the source gas G1 and the source gas G2 react on the substrate W in the reaction tube 12. Subsequently, when the compound semiconductor film M reaches a predetermined thickness, the supply of the raw material gas G1 is stopped, the carrier gas is supplied, the heater is stopped, and the temperature of the reaction tube 12 is lowered to room temperature. When the temperature is sufficiently lowered, the substrate W on which the compound semiconductor film M has been grown is taken out from the reaction tube 12.

  In the vapor phase growth apparatus 10 of the present embodiment, the raw material gas G2 and the raw material gas G1 are mixed in the vicinity of the supply port 28. At this time, the gas flow adjusting unit 32 significantly suppresses the retention of the raw material gases G1 and G2 on the outer peripheral surface of the supply pipe 24, and the mixed gas is supplied to the supply port before the raw material gas G2 and the raw material gas G1 react with each other. Escape from 28. Therefore, a situation in which the source gas G1 and the source gas G2 react at the end portion 26 of the supply pipe 24 and a compound semiconductor such as AlN is deposited on the supply pipe 24 is suppressed. That is, the reaction between the source gas G1 and the source gas G2 easily occurs on the substrate W, and the source gases G1 and G2 are efficiently used for forming the compound semiconductor film (AlN film) M on the substrate W. . In addition, since the generation of vortex is suppressed by the gas flow adjusting unit 32, the source gas G2 flowing out from the supply port 30 serves as an air curtain, and the source gas G1 flows toward the inner wall of the reaction tube 12. Is suppressed, and the compound semiconductor film (AlN film) is hardly deposited on the inner wall. Therefore, in the vapor phase growth apparatus 10 of the present embodiment, the utilization efficiency of the source gas can be increased and the introduction of defects into the growth film can be suppressed.

  Further, when the gas flow adjusting unit 32 has the first portion 32a and the second portion 32b, the source gas G2 flows through the space SP without generating vortex, so that the use efficiency of the source gas is high and the growth is achieved. It is possible to further suppress the introduction of defects into the film.

  FIG. 3 is a diagram schematically showing a modification of the vapor phase growth apparatus according to the first embodiment provided with a gas flow adjusting unit having a preferable shape. The vapor phase growth apparatus 10A shown in FIG. 3 has a gas flow adjustment unit 32A of y = 2 mm instead of the gas flow adjustment unit 32 of the vapor phase growth apparatus 10 shown in FIGS. It has the same configuration as the phase growth apparatus 10. The second portion 32 b of the gas flow adjusting unit 32 A is narrowed until the outer diameter thereof becomes equal to the edge of the supply port 28 at the position of the supply port 28, and is equal to the diameter of the supply port 28. That is, the gas flow adjusting unit 32A has only an inclined surface at the position of the supply port 28, and a plane orthogonal to the tube axis direction is not substantially formed. In other words, the end portion 26 of the supply pipe 24 has a sharpened shape at the position of the supply port 28 by the gas flow adjusting portion 32A. On the other hand, when the end 26 of the supply pipe 24 is not sharpened by the gas flow adjusting unit 32 (y> 2 mm) as in the vapor phase growth apparatus 10 shown in FIG. The gases G1 and G2 stay and the reaction product tends to accumulate on the front end surface 24a of the supply pipe 24. When the reaction product is peeled off to generate particles (fine particles), the particles adhere to the substrate W disposed near the supply port 28, and defects are introduced into the compound semiconductor film M grown on the substrate W. May be caused.

  In the vapor phase growth apparatus 10A of the present embodiment, the mixing of the source gas G2 and the source gas G1 occurs near the supply port 28. At this time, since the supply pipe 24 is sharpened by the gas flow adjusting portion 32A, the stagnation of the source gases G1 and G2 on the outer peripheral surface of the supply pipe 24 is further suppressed, and the source gas G2 and the source gas G1 are reduced. The mixed gas flows out from the supply port 28 before the reaction. Therefore, the situation where the source gas G1 and the source gas G2 react at the end portion 26 of the supply pipe 24 and a compound semiconductor such as AlN is deposited on the supply pipe 24 is further suppressed. That is, the reaction between the source gas G1 and the source gas G2 easily occurs on the substrate W, and the source gases G1 and G2 are efficiently used for forming the compound semiconductor film (AlN film) M on the substrate W. . In addition, since the generation of vortex is suppressed by the gas flow adjusting unit 32A, the source gas G2 flowing out from the supply port 30 serves as an air curtain, and the source gas G1 flows toward the inner wall of the reaction tube 12 Is suppressed, and the compound semiconductor film (AlN film) is hardly deposited on the inner wall.

  As described in detail above, in the vapor phase growth apparatus 10A according to the present embodiment, the source gas G2 supplied from the supply port 30 flows to the vicinity of the supply port 28 without stagnation by the gas flow adjusting unit 32A. It reacts with the source gas G1. Therefore, the source gas G1 and the source gas G2 react on the substrate W. That is, in the vapor phase growth apparatus 10A, the utilization efficiency of the source gases G1 and G2 is further improved as compared with the vapor phase growth apparatus 10. In addition, since film growth at a place other than on the substrate W is difficult to occur, a situation in which defects are introduced into the compound semiconductor film M is further suppressed.

  In addition, when the position shift of the direction orthogonal to the tube axis of the supply pipe 24 arises, and the deviation arises with respect to the reaction tube 12, the balance of the flow of source gas G2 will be broken. In this case, the effect of the air curtain by the source gas G2 described above is reduced, and a large amount of compound semiconductor film (AlN film) is formed on the inner wall of the reaction tube 12. In order to prevent such a situation, the shortest distance d between the maximum outer diameter portion of the gas flow adjusting portion 32A and the inner wall surface of the reaction tube 12 is somewhat larger than an assumed positional deviation (for example, 10 times or more). It is preferable to design. In other words, the maximum outer diameter of the gas flow adjusting unit 32A is preferably designed to be somewhat smaller than the inner diameter of the reaction tube 12. However, if the bulge of the gas flow adjusting part 32A is too small, the flow of the source gas G2 toward the center of the substrate is weakened, and the uniformity of the growth rate on the substrate cannot be maintained, which is not preferable.

Furthermore, in the above-described embodiment, the AlCl ₃ gas of the source gas G1 has a higher specific gravity than the NH ₃ gas of the source gas G2. Therefore, the flow of the source gas G1 tends to bend in the direction of gravity (vertical direction in FIG. 1). Therefore, in order to mix the source gases G1 and G2 more uniformly, the reaction tube 12 and the supply tube 24 are extended in the vertical direction so that the flow of the source gases G1 and G2 and the direction of gravity coincide with each other. It is preferable to use a mold type device.

(Second Embodiment)
FIG. 4 is a diagram schematically showing a vapor phase growth apparatus according to the second embodiment. A vapor phase growth apparatus 10B shown in FIG. 4 has the same configuration as the vapor phase growth apparatus 10 except that a supply device 23A is provided instead of the supply device 23. The supply device 23A is inserted in the supply pipe 24 in addition to the generation pipe 21 and the supply pipe 24 shown in the first embodiment, and has an inner supply pipe 33 (a third supply pipe) for flowing the source gas G1. Supply pipe) and a supply pipe 34 for supplying gas G5 (for example, N ₂ gas) that does not react with the source gases G1 and G2 from the outside of the reaction pipe 12 to the supply pipe 24. The supply pipe 24 and the inner supply pipe 33 form a double pipe structure. A space SPA for supplying the gas G5 into the reaction tube 12 is formed between the outer wall of the inner supply tube 33 and the inner wall of the supply tube 24.

  The inner supply pipe 33 extends along the extending direction of the supply pipe 24 from the end of the production pipe 21 on the supply pipe 24 side to the end 26 of the supply pipe 24, and the source gas G1 produced in the production pipe 21 To the supply port 28 of the supply pipe 24. The supply pipe 34 is connected to the end 25 of the supply pipe 24, and sends the gas G <b> 5 to the inside of the supply pipe 24 and to the outside of the inner supply pipe 33. That is, the gas G5 is supplied to the reaction tube 12 from the third supply port 36 formed between the supply tube 24 and the inner supply tube 33.

  In addition to the effects of the vapor phase growth apparatus 10A described above, the vapor phase growth apparatus 10B has the following effects. That is, the supply port 28 of the supply pipe 24 is provided with a supply port 36 for supplying the gas G5 around the supply port 38 of the inner supply pipe 33 for supplying the source gas G1. Therefore, at the position of the supply port 28 of the supply pipe 24, the gas G5 supplied from the supply port 28 becomes a barrier, and mixing of the source gas G1 and the source gas G2 is suppressed. Therefore, the source gas G1 and the source gas G2 are mixed at a position closer to the substrate W, and the compound semiconductor film M is efficiently grown on the substrate W. That is, in the vapor phase growth apparatus 10B, the gas G5 supplied from the supply port 36 suppresses a situation in which the source gas G1 and the source gas G2 react at the position of the supply port 28. Therefore, the source gas G1. , G2 utilization efficiency is further improved.

  As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment. In the embodiment described above, the shape of the reaction tube and the supply tube is a cylindrical tube having a substantially circular cross section perpendicular to the gas flow. For example, the same effect can be obtained even if the cross section is a polygonal tube such as a triangle or a rectangle. can get. Even in this case, the cross-sectional shape parallel to the gas flow of the gas flow adjusting unit is the same as described above, but the cross-sectional shape perpendicular to the gas flow is similar to the cross-sectional shape of the reaction tube and the supply tube. Become.

  Further, in the above description, the substrate and the substrate holder are arranged so that the substrate surface is parallel to the gas flow, but the same is true even if the substrate and the substrate holder are arranged so that the substrate surface is perpendicular to the gas flow. An effect is obtained. In this case, when arranging one board | substrate, it is preferable to arrange | position so that the center of a board | substrate may come on the tube axis | shaft of a reaction tube. A plurality of substrates may be arranged so as to surround the tube axis of the reaction tube.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

  Hereinafter, Examples 1 to 14 and Comparative Examples 1 and 2 will be described in detail.

(Example 1)
An AlN film was grown on the SiC substrate using the vapor phase growth apparatus 10 shown in FIGS. As the vapor phase growth apparatus 10, an apparatus having x of 10 mm, L of 100 mm, d of 10 mm, y of 2 mm, l of 50 mm, and m of 150 mm was used (see FIG. 2). The distance d1 between the supply port 28 in the tube axis direction of the reaction tube 12 and the center point of the SiC substrate surface was set to about 50 mm. After the SiC substrate was placed on the substrate holder 14, the temperature of the substrate holder 14 was raised to 1100 ° C. Al pellets were used as the Al raw material. While the Al pellets placed on the quartz boat were heated to 500 ° C., HCl gas diluted with N ₂ gas was flowed to generate AlCl ₃ gas. On the other hand, NH ₃ gas was used as a nitrogen raw material. The gas flow rate was adjusted so that the average AlCl ₃ partial pressure in the reaction tube 12 was 0.01 atm and the NH ₃ partial pressure was 0.2 atm. The HCl partial pressure was 0.03 atm.

  After the AlN crystal was grown for 30 hours under the above-described conditions, the SiC substrate with the AlN film grown on the surface was taken out from the reaction tube 12. Since the thickness of the AlN film was 1110 μm, the growth rate of the AlN crystal could be estimated to be 37 μm / hr. On the other hand, an AlN film having a thickness of about 140 μm was deposited at the supply port 28.

(Example 2)
An AlN film was grown in the same manner as in Example 1 except that l of the vapor phase growth apparatus 10 was set to 100 mm. As a result, since the thickness of the AlN film was 1230 μm, the growth rate of the AlN crystal could be estimated to be 41 μm / hr. On the other hand, an AlN film having a thickness of about 120 μm was deposited at the supply port 28.

(Example 3)
A GaN film was grown on the sapphire substrate using the vapor phase growth apparatus 10 shown in FIGS. As the vapor phase growth apparatus 10, an apparatus having x of 10 mm, L of 100 mm, d of 10 mm, y of 2 mm, l of 150 mm, and m of 150 mm was used (see FIG. 2). The distance d1 between the supply port 28 in the tube axis direction of the reaction tube 12 and the center point of the substrate surface was about 50 mm. After the sapphire substrate was placed on the substrate holder 14, the temperature of the substrate holder 14 was raised to 1050 ° C. Ga melt was used as the Ga raw material. In a state where the Ga melt placed on the quartz boat was heated to 800 ° C., HCl gas diluted with H ₂ gas was flowed to generate GaCl gas. On the other hand, NH ₃ gas was used as a nitrogen raw material. The gas flow rate was adjusted so that the average partial pressure of GaCl in the reaction tube 12 was 0.01 atm and the NH ₃ partial pressure was 0.2 atm. The HCl partial pressure was 0.01 atm.

  After the GaN crystal was grown for 30 hours under the above conditions, the substrate on which the GaN film was grown was taken out from the reaction tube 12. Since the film thickness of the GaN film was 2460 μm, the growth rate of the GaN crystal could be estimated as 82 μm / hr. On the other hand, a GaN film having a thickness of about 320 μm was deposited at the supply port 28.

Example 4
An AlN film was grown in the same manner as in Example 1 except that l of the vapor phase growth apparatus 10 was set to 150 mm. As a result, since the thickness of the AlN film was 840 μm, the growth rate of the AlN crystal could be estimated to be 28 μm / hr. On the other hand, an AlN film having a thickness of about 160 μm was deposited at the supply port 28.

(Example 5)
An AlN film was grown in the same manner as in Example 1 except that l of the vapor phase growth apparatus 10 was 20 mm and m was 0 mm. As a result, since the film thickness of the AlN film was 1140 μm, the growth rate of the AlN crystal could be estimated to be 38 μm / hr. On the other hand, an AlN film having a thickness of about 140 μm was deposited at the supply port 28.

(Example 6)
An AlN film was grown in the same manner as in Example 1 except that l of the vapor phase growth apparatus 10 was 50 mm and m was 0 mm. As a result, since the thickness of the AlN film was 840 μm, the growth rate of the AlN crystal could be estimated to be 28 μm / hr. On the other hand, an AlN film having a thickness of about 160 μm was deposited at the supply port 28.

(Example 7)
An AlN film was grown in the same manner as in Example 1 except that l of the vapor phase growth apparatus 10 was set to 100 mm and m was set to 0 mm. As a result, since the thickness of the AlN film was 690 μm, the growth rate of the AlN crystal could be estimated to be 23 μm / hr. On the other hand, an AlN film having a thickness of about 190 μm was deposited at the supply port 28.

(Example 8)
A GaN film was grown in the same manner as in Example 3 except that l of the vapor phase growth apparatus 10 was 20 mm and m was 0 mm. As a result, since the film thickness of the GaN film was 1950 μm, the growth rate of the GaN crystal could be estimated to be 65 μm / hr. On the other hand, a GaN film having a thickness of about 450 μm was deposited at the supply port 28.

Example 9
A GaN film was grown in the same manner as in Example 3 except that l of the vapor phase growth apparatus 10 was 20 mm and m was 50 mm. As a result, since the film thickness of the GaN film was 3600 μm, the growth rate of the GaN crystal could be estimated to be 120 μm / hr. On the other hand, a GaN film having a thickness of about 110 μm was deposited at the supply port 28.

(Example 10)
An AlN film was grown in the same manner as in Example 1 except that l of the vapor phase growth apparatus 10 was set to 100 mm and m was set to 0 mm. As a result, since the thickness of the AlN film was 810 μm, the growth rate of the AlN crystal could be estimated to be 27 μm / hr. On the other hand, an AlN film having a thickness of about 160 μm was deposited at the supply port 28.

(Example 11)
An AlN film was grown in the same manner as in Example 1 except that l of the vapor phase growth apparatus 10 was set to 0 mm and m was set to 100 mm. As a result, since the thickness of the AlN film was 1080 μm, the growth rate of the AlN crystal could be estimated to be 36 μm / hr. On the other hand, an AlN film having a thickness of about 130 μm was deposited at the supply port 28.

Example 12
A GaN film was grown in the same manner as in Example 3 except that l of the vapor phase growth apparatus 10 was 0 mm and m was 100 mm. As a result, since the film thickness of the GaN film was 2160 μm, the growth rate of the GaN crystal could be estimated as 72 μm / hr. On the other hand, a GaN film having a thickness of about 340 μm was deposited at the supply port 28.

(Example 13)
An AlN film was grown in the same manner as in Example 1 except that y of the vapor phase growth apparatus 10 was 10 mm, l was 100 mm, and m was 100 mm. As a result, since the thickness of the AlN film was 1080 μm, the growth rate of the AlN crystal could be estimated to be 36 μm / hr. On the other hand, an AlN film having a thickness of about 140 μm was deposited at the supply port 28.

(Example 14)
An AlN film was grown in the same manner as in Example 1 except that y of the vapor phase growth apparatus 10 was 20 mm, l was 100 mm, and m was 100 mm. As a result, since the thickness of the AlN film was 1050 μm, the growth rate of the AlN crystal could be estimated to be 35 μm / hr. On the other hand, an AlN film having a thickness of about 130 μm was deposited at the supply port 28.

(Comparative Example 1)
An AlN film was grown in the same manner as in Example 1 except that d of the vapor phase growth apparatus was 45 mm, l was 0 mm, and m was 0 mm. In the grown film, about 100 pieces of film-like fragments considered to be AlN having a diameter of about 50 to 300 μm were observed. Further, since the thickness of the AlN film was 294 μm, the growth rate of the AlN crystal could be estimated to be 9.8 μm / hr. On the other hand, an AlN film having a thickness of about 680 μm was deposited at the supply port. A high defect region is formed around the fragments of the growth film. When the growth film was confirmed using TEM, the dislocation density was as low as about 2 × 10 ⁶ / cm ^{2 in the} region other than the high defect region. On the other hand, in the high defect region, the dislocation density was as high as 5 × 10 ⁷ / cm ² . It is considered that the fragments observed in the AlN film peel off the AlN film deposited on the gas supply port during the film growth and adhere to the growth film. For this reason, it is considered that a high defect area has occurred around the fragments of the growth film.

(Comparative Example 2)
A GaN film was grown in the same manner as in Example 3 except that d of the vapor phase growth apparatus was 45 mm, l was 0 mm, and m was 0 mm. Since the film thickness of the GaN film was 516 μm, the growth rate of the GaN crystal could be estimated to be 17.2 μm / hr. On the other hand, a GaN film having a thickness of about 1350 μm was deposited at the supply port. On the surface or inside of the GaN film, film-like fragments considered to be GaN having a diameter of about 50 to 300 μm were observed at a density of about 5 pieces / cm ² . When the obtained crystal was polished and observed by cathodoluminescence (CL), a high defect region was formed around the fragments, and dislocations of 4 × 10 ⁶ / cm ² or less were formed in regions other than the high defect region. In contrast to the density, the dislocation density increased to 1 × 10 ⁷ / cm ² or more in the high defect region (region 300 μm from the fragment). The debris observed in the GaN film is thought to be due to the GaN film deposited at the gas supply port being peeled off.

On the other hand, in Examples 1 to 14, the film-like fragments observed in the comparative example are not substantially observed on the surface or inside of the film grown on the substrate, and the dislocation density of any crystal film is 1 × 10 ⁶ / cm ² or less was favorable. That is, in Examples 1 to 14 according to the present invention, a good compound semiconductor film with few crystal defects cannot be obtained. When a semiconductor element is manufactured using such a compound semiconductor film, the defect of the element is caused. The malfunction of is significantly reduced.

It is a figure which shows typically the vapor phase growth apparatus which concerns on 1st Embodiment. It is a figure which shows typically the principal part of the vapor phase growth apparatus shown by FIG. It is a figure which shows typically the modification of the vapor phase growth apparatus which concerns on 1st Embodiment provided with the gas flow adjustment part of a preferable shape. It is a figure which shows typically the vapor phase growth apparatus which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,10A, 10B ... Vapor phase growth apparatus, 12 ... Reaction tube, 14 ... Substrate holder, 16 ... Second supply tube, 24 ... First supply tube, 26 ... End of first supply tube, 28 ... 1st supply port, 30 ... 2nd supply port, 32, 32A ... Gas flow control part, 32a ... 1st part, 32b ... 2nd part, 33 ... Inner supply pipe (3rd supply pipe), 36 ... 3rd supply port, G1 ... 1st source gas, G2 ... 2nd source gas, G5 ... gas, M ... Compound semiconductor film (compound semiconductor), W ... Substrate.

Claims (5)

A reaction tube for growing a compound semiconductor by mixing a first source gas and a second source gas; and inserted into the reaction tube, for supplying the first source gas into the reaction tube A first supply pipe;
A second supply pipe connected to the reaction pipe for supplying the second source gas into the reaction pipe;
A substrate holder for holding a substrate near a first supply port formed at an end portion of the first supply tube located in the reaction tube;
The first supply pipe and the reaction tube form a double tube structure by having the outer wall of the first supply pipe facing the inner wall of the reaction tube,
The second supply pipe is connected to the reaction tube so that a space formed between the outer wall of the first supply pipe and the inner wall of the reaction tube becomes a flow path for the second source gas. And
The end of the first supply pipe located in the reaction tube has a gas flow adjustment that swells toward the inner wall of the reaction tube so as to reduce the cross-sectional area of the flow path of the second source gas. A vapor phase growth apparatus provided with a section.   The gas flow adjusting portion is positioned on the first supply port side from the first portion, the first portion having an outer periphery extending toward the first supply port, and toward the first supply port. The vapor phase growth apparatus according to claim 1, further comprising a second portion whose outer periphery is narrowed. A third supply pipe inserted into the first supply pipe for flowing the first source gas;
The first supply pipe and the third supply pipe form a double pipe structure;
A space for supplying a gas that does not react with the first and second source gases into the reaction tube is formed between the outer wall of the third supply tube and the inner wall of the first supply tube. The vapor phase growth apparatus according to claim 1 or 2.   A compound semiconductor film grown using the vapor phase growth apparatus according to claim 1. A method for growing a compound semiconductor film, comprising growing a compound semiconductor film using the vapor phase growth apparatus according to claim 1.

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