JP2019220589A - Vapor growth device - Google Patents

Abstract

PURPOSE: To provide a vapor growth device that forms a high quality film.CONSTITUTION: A vapor growth device according to an embodiment includes a reaction chamber, a holder provided in the reaction chamber and holding the substrate, a rotation drive mechanism that rotates the holder, a gas mixing mechanism that mixes a first gas containing a Lewis acid and a second gas containing a Lewis base to generate a mixed gas, and a shower plate that includes a plurality of gas ejection holes that are provided between the reaction chamber and the gas mixing mechanism, and eject the mixed gas into the reaction chamber, and arithmetic mean roughness of the surface on the reaction chamber side between the gas ejection holes is 0.05 μm or more and 50 μm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vapor deposition apparatus for forming a film on a substrate by supplying a gas.

  A High Electron Mobility Transistor (HEMT) using a GaN-based semiconductor (GaN based semiconductor) realizes a high withstand voltage and a low on-resistance. The HEMT uses a two-dimensional electron gas (2DEG) induced at a hetero interface between a stacked channel layer and a barrier layer as a current path.

  For example, a gallium nitride (hereinafter, also referred to as GaN) film is used for the channel layer, and an aluminum gallium nitride (hereinafter, also referred to as AlGaN) film is used for the barrier layer. The use of an indium aluminum nitride (hereinafter, also referred to as InAlN) film as a barrier layer instead of the aluminum gallium nitride film has been studied.

  Since the InAlN film has a large spontaneous polarization, the 2DEG concentration at the interface between the InAlN film and the GaN film can be increased. Therefore, a HEMT having a low on-resistance can be realized. Further, by setting the In composition (In / (In + Al)) in the InAlN film to about 17 atomic%, lattice matching with the GaN film can be realized. Therefore, distortion due to lattice mismatch is eliminated, and HEMT reliability is improved.

  Further, the laminated structure of the InAlN film and the GaN film is also expected to be applied to a dielectric mirror used for a surface emitting laser or the like. For application to the above dielectric mirror, it is required that the interface between the GaN film and the InAlN film is clear, that is, the compound composition of the two films changes sharply.

  However, in the vapor phase growth of an InAlN film, unintended gallium (Ga) incorporation into the InAlN film (unintended Ga incorporation) has become a problem. If gallium is taken into the InAlN film, for example, a decrease in the 2DEG density at the interface between InAlN and GaN and a decrease in electron mobility may occur. In addition, since a sharp change in the compound composition cannot be obtained, it is difficult to form a good dielectric mirror.

  The cause of the unintended incorporation of Ga into the InAlN film is considered as follows. During the growth of the Ga-containing film before the growth of the InAlN film, a reaction product containing Ga adheres to an upstream portion of the vapor phase growth apparatus. Then, Ga is released from the reaction product containing Ga into the growth atmosphere during the growth of the InAlN film. This Ga is taken into the InAlN film.

  Non-Patent Document 1 discloses FIG. An InAlN film formed by using an apparatus for supplying a separation gas shown in FIG. 1B is described.

U.S. Patent Application Publication No. 2010/0143588

J. Lu et al. "Epitaxial Growth of InAlN / GaN Heterostructures on Silicon Substrates in a Single Wafer Rotating Disk MOCVD Reactor", MRS Advances, 2017.

  An object of the present invention is to provide a vapor phase growth apparatus for forming a high quality film.

  A vapor phase growth apparatus according to one embodiment of the present invention includes a reaction chamber, a holder provided in the reaction chamber, the holder holding a substrate, a rotation driving mechanism for rotating the holder, and a first gas including a Lewis acid. A gas mixing mechanism for mixing the second gas containing the Lewis base and the second gas to generate a mixed gas; and a plurality of gas mixing mechanisms provided between the gas mixing mechanism and the reaction chamber for ejecting the mixed gas into the reaction chamber. And a shower plate having an arithmetic average roughness of 0.05 μm or more and 50 μm or less on a surface of the reaction chamber side between the gas ejection holes.

  In the vapor phase growth apparatus of the above aspect, it is preferable that the arithmetic average roughness of the surface is 0.1 μm or more and 10 μm or less.

  In the vapor phase growth apparatus of the above aspect, it is preferable that a maximum height difference of the surface between the adjacent gas ejection holes is equal to or less than a distance between centers of the adjacent gas ejection holes.

  In the vapor phase growth apparatus of the above aspect, it is preferable that the maximum height difference is smaller than the diameter of the gas ejection hole.

  In the vapor phase growth apparatus according to the above aspect, it is preferable that the gas mixing mechanism includes a mixed gas chamber filled with the mixed gas, and the gas ejection hole is connected to the mixed gas chamber.

  According to the present invention, it is possible to provide a vapor phase growth apparatus for forming a high-quality film.

FIG. 2 is a schematic sectional view of the vapor phase growth apparatus of the first embodiment. FIG. 2 is a schematic top view of the shower plate according to the first embodiment. FIG. 2 is an enlarged schematic cross-sectional view of a part of the shower plate according to the first embodiment. FIG. 2 is an enlarged schematic cross-sectional view of a part of the surface of the shower plate according to the first embodiment. FIG. 4 is an explanatory diagram of the effect of the first embodiment. FIG. 9 is an enlarged schematic cross-sectional view of a part of the shower plate according to the second embodiment. FIG. 9 is an explanatory diagram of an effect of the second embodiment. FIG. 10 is an enlarged schematic cross-sectional view of a part of the shower plate according to the third embodiment. FIG. 9 is a schematic cross-sectional view of a vapor phase growth apparatus according to a fourth embodiment.

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

  In this specification, the same or similar members may be denoted by the same reference numerals.

  In this specification, the direction of gravity in a state where the vapor phase growth apparatus is installed so that a film can be formed is defined as “down”, and the opposite direction is defined as “up”. Therefore, “lower” means a position in the direction of gravity with respect to the reference, and “downward” means a direction of gravity with respect to the reference. "Up" means a position in the direction opposite to the direction of gravity with respect to the reference, and "upper" means a direction opposite to the direction of gravity with respect to the reference. The “vertical direction” is the direction of gravity.

  In this specification, “process gas” is a general term for gases used for forming a film on a substrate, and includes, for example, a source gas, a carrier gas, a diluent gas, and the like.

(1st Embodiment)
The vapor phase growth apparatus of the first embodiment includes a reaction chamber, a holder provided in the reaction chamber and holding a substrate, a rotation driving mechanism for rotating the holder, a first gas containing a Lewis acid, and a Lewis acid. A gas mixing mechanism for mixing the second gas containing the base to generate a mixed gas; and a plurality of gas ejection holes provided between the gas mixing mechanism and the reaction chamber for ejecting the mixed gas into the reaction chamber. A shower plate having an arithmetic average roughness of 0.05 μm or more and 50 μm or less on the surface of the reaction chamber between the gas ejection holes.

  FIG. 1 is a schematic sectional view of the vapor phase growth apparatus of the first embodiment. The vapor phase growth apparatus of the first embodiment is, for example, a single wafer type epitaxial growth apparatus using a metal organic chemical vapor deposition method (MOCVD method).

  The vapor phase growth apparatus of the first embodiment includes a reaction chamber 100, a shower plate 200, a mixed gas chamber 300, a first gas supply path 11, a second gas supply path 12, and a third gas supply path 13. ing. The reaction chamber 100 includes a holder 15, a rotator unit 16, a wall surface 17, a rotation shaft 18, a rotation drive mechanism 19, an in-heater 24, an out-heater 26, a reflector 28, a support column 34, a fixed base 36, a fixed shaft 38, and a gas outlet. 40. The shower plate 200 has a plurality of gas ejection holes 22. The mixed gas chamber 300 has a gas supply port 20 and a wall surface 27. The first gas supply path 11, the second gas supply path 12, and the third gas supply path 13 have a junction 50. The mixed gas chamber 300 and the merging section 50 are an example of a gas mixing mechanism (gas mixer).

  The first gas supply path 11, the second gas supply path 12, and the third gas supply path 13 are connected to a gas supply port 20, and supply a process gas to the mixed gas chamber 300.

  The first gas supply path 11 supplies a first process gas (first gas) containing a Lewis acid. The first gas supply path 11 supplies, for example, a first process gas containing an organic metal of a group III element and a carrier gas to the mixed gas chamber 300.

  A plurality of first gas supply paths 11 may be provided. For example, different first process gases can be supplied through a plurality of first gas supply paths 11. The first process gas is, for example, a gas containing a group III element for forming a group III-V semiconductor film on a wafer.

  Group III elements are, for example, gallium (Ga), aluminum (Al), and indium (In). The organic metal is, for example, trimethylgallium (TMG), trimethylaluminum (TMA), or trimethylindium (TMI).

  The second gas supply path 12 supplies a second process gas (second gas) containing a Lewis base. The second gas supply path 12 supplies, for example, a second process gas containing a nitrogen compound serving as a source of nitrogen (N) to the mixed gas chamber 300.

The nitrogen compound is, for example, ammonia (NH ₃ ). The second process gas is, for example, a group V element source gas for forming a group III-V semiconductor film on a wafer. The group V element is nitrogen (N).

  The nitrogen compound may be any active nitrogen compound, and is not limited to ammonia. Other nitrogen compounds such as hydrazine, alkylhydrazine, and alkylamine may be used.

  The third gas supply path 13 supplies the third process gas to the mixed gas chamber 300. The third process gas is, for example, a diluent gas for diluting the first process gas and the second process gas. By diluting the first process gas and the second process gas with the diluent gas, the concentrations of the group III element and the group V element supplied from the mixed gas chamber 300 to the reaction chamber 100 are adjusted. The dilution gas is, for example, an inert gas such as a hydrogen gas, a nitrogen gas, or an argon gas, or a mixed gas thereof.

  The first gas supply path 11, the second gas supply path 12, and the third gas supply path 13 join at a junction 50 provided upstream of the gas supply port 20. Therefore, the first process gas, the second process gas, and the third process gas are mixed before the gas supply port 20 to form a mixed gas. A mixed gas of the first process gas, the second process gas, and the third process gas is supplied from the gas supply port 20 into the mixed gas chamber 300.

  The mixed gas chamber 300 has a wall surface 27. The wall surface 27 is made of, for example, stainless steel.

  The mixing of the process gas does not necessarily have to be completely performed in the pipe upstream of the mixed gas chamber 300, and the mixing of the process gas may further proceed in the mixed gas chamber 300.

  The mixed gas chamber 300 and the merging section 50 are examples of a gas mixing mechanism. The first process gas and the second process gas are mixed by the gas mixing mechanism to generate a mixed gas.

  FIG. 2 is a schematic top view of the shower plate according to the first embodiment. FIG. 3 is an enlarged schematic cross-sectional view of a part of the shower plate according to the first embodiment. FIG. 3A is a cross-sectional view taken along the line AA ′ of FIG. 2, and FIG. 3B is a cross-sectional view taken along the line BB ′ of FIG.

  Shower plate 200 is provided between mixed gas chamber 300 and reaction chamber 100. The shower plate 200 is provided above the reaction chamber 100. The shower plate 200 has the gas ejection holes 22. The plurality of gas ejection holes 22 are repeatedly arranged at a predetermined pitch, for example. The gas ejection holes 22 are connected to the mixed gas chamber 300. The gas ejection holes 22 have a function of ejecting the mixed gas from the mixed gas chamber 300 into the reaction chamber 100.

  The shower plate 200 is, for example, metal. The shower plate 200 is, for example, aluminum. For example, a metal plating layer is formed on the surface of the shower plate 200 on the side of the reaction chamber 100. The metal plating layer is, for example, a nickel layer formed by electroless plating.

  FIG. 3 is an enlarged schematic cross-sectional view of a part of the shower plate according to the first embodiment. FIG. 3A is a cross section corresponding to the AA ′ cross section in FIG. 2, and FIG. 3B is a cross section corresponding to the BB ′ cross section in FIG.

  As shown in FIGS. 3A and 3B, the shower plate 200 has the same shape in both the AA ′ section and the BB ′ section. The position of the end of the adjacent gas ejection hole of the shower plate 200 on the side of the reaction chamber 100 exists in the same plane.

  The distance between the centers of the adjacent gas ejection holes 22 (L in FIGS. 3A and 3B) is, for example, 10 mm or less. The hole diameter (D in FIGS. 3A and 3B) of the gas ejection holes 22 is, for example, 0.05 mm or more and 3 mm or less.

  FIG. 4 is an enlarged schematic cross-sectional view of a part of the surface S of the shower plate 200. FIG. 4 is an enlarged view of, for example, a portion between the gas ejection holes 22 surrounded by a dotted circle in FIG. The surface S of the shower plate 200 on the side of the reaction chamber has irregularities.

  The arithmetic average roughness (Ra) of the surface S of the shower plate 200 on the side of the reaction chamber is 0.05 μm or more and 50 μm or less. The arithmetic average roughness (Ra) of the surface S between the gas ejection holes 22 of the shower plate 200 is 0.05 μm or more and 50 μm or less. The reference length for calculating the arithmetic average roughness (Ra) is, for example, 1 mm.

  The reaction chamber 100 includes, for example, a cylindrical wall surface 17 made of stainless steel.

  The holder 15 is provided inside the reaction chamber 100. A wafer W, which is an example of a substrate, can be placed on the holder 15. The holder 15 is, for example, annular. The holder 15 has an opening at the center. Such an annular holder 15 can be used when an opaque substrate such as a Si substrate is used, for example, and high in-plane uniformity can be obtained. Note that the shape of the holder 15 may be a substantially flat plate type having no cavity in the center.

  For example, one wafer W is placed on the holder 15. A configuration in which a plurality of wafers W are placed on the holder 15 is also possible.

  The holder 15 is formed using, for example, ceramics such as silicon carbide (SiC), tantalum carbide (TaC), boron nitride (BN), and pyrolytic graphite (PG), or carbon as a base material. For the holder 15, for example, carbon coated with SiC, BN, TaC, PG, or the like can be used.

  The holder 15 is fixed to an upper part of the rotator unit 16. The rotator unit 16 is fixed to a rotating shaft 18. The holder 15 is indirectly fixed to the rotation shaft 18.

  The distance between the wafer W mounted on the holder 15 and the shower plate 200 is, for example, 5 cm or more and 10 cm or less.

  The rotation shaft 18 is rotatable by a rotation drive mechanism 19. The holder 15 can be rotated by rotating the rotation shaft. By rotating the holder 15, the wafer W mounted on the holder 15 can be rotated at a high speed. At this time, one wafer W can be rotated. The rotation means that the wafer W rotates around a normal passing through the approximate center of the wafer W as a rotation axis. Note that a plurality of wafers W arranged rotationally symmetrically may be revolved.

  For example, the wafer W is rotated at a rotation speed of 300 rpm or more and 3000 rpm or less. The rotation drive mechanism 19 includes, for example, a motor and a bearing.

  The in-heater 24 and the out-heater 26 are provided below the holder 15. The in-heater 24 and the out-heater 26 are provided in the rotator unit 16. The outer heater 26 is provided between the inner heater 24 and the holder 15.

  The in-heater 24 and the out-heater 26 heat the wafer W held by the holder 15. The in-heater 24 heats at least a central portion of the wafer W. The out heater 26 heats the outer peripheral area of the holder 15 and the wafer W. The in-heater 24 has, for example, a disk shape. The out heater 26 is, for example, annular.

  The reflector 28 is provided below the inner heater 24 and the outer heater 26. Between the reflector 28 and the holder 15, an in-heater 24 and an out-heater 26 are provided.

  The reflector 28 reflects heat radiated downward from the in-heater 24 and the out-heater 26 to improve the heating efficiency of the wafer W. Further, the reflector 28 prevents a member below the reflector 28 from being heated. The reflector 28 has, for example, a disk shape.

  The reflector 28 is formed of a material having high heat resistance. The reflector 28 has, for example, heat resistance to a temperature of 1100 ° C. or higher.

  The reflector 28 is formed using, for example, a ceramic such as SiC, TaC, carbon, BN, or PG, or a metal such as tungsten as a base material. When ceramics are used for the reflector 28, a sintered body or a substrate produced by vapor phase growth can be used. As the reflector 28, a carbon base material or the like coated with ceramics such as SiC, TaC, BN, PG, and glassy carbon may be used.

  The reflector 28 is fixed to a fixed base 36 by, for example, a plurality of support columns 34. The fixed base 36 is supported by, for example, a fixed shaft 38.

  A push-up pin (not shown) is provided in the rotator unit 16 to detach the wafer W from the holder 15. The push-up pin penetrates, for example, the reflector 28 and the in-heater 24.

  The gas outlet 40 is provided at the bottom of the reaction chamber 100. The gas discharge port 40 discharges a surplus reaction product after the process gas reacts on the surface of the wafer W and a surplus process gas to the outside of the reaction chamber 100.

  Further, on the wall surface 17 of the reaction chamber 100, an unillustrated wafer inlet / outlet and a gate valve are provided. The wafer W can be carried into or out of the reaction chamber 100 by the wafer entrance and the gate valve.

  Next, a vapor phase growth method using the vapor phase growth apparatus of the first embodiment will be described.

  Hereinafter, an example in which an indium aluminum nitride film (InAlN film) is continuously formed on a gallium nitride film (GaN film) will be described. For example, the GaN film is used as a HEMT channel layer, and the InAlN film is used as a HEMT barrier layer. Note that the band gap of the material of the barrier layer of the HEMT is larger than the band gap of the material of the channel layer.

  First, the wafer W is carried into the reaction chamber 100. The wafer W is, for example, a silicon substrate having a {111} surface. The thickness of the silicon substrate is, for example, not less than 700 μm and not more than 1.2 mm. Note that the {111} plane indicates a plane which is crystallographically equivalent to the (111) plane.

  Next, the wafer W is placed on the holder 15. Next, the wafer W is heated by the in-heater 24 and the out-heater 26 provided below the holder 15 while being rotated by the rotation drive mechanism 19.

  Next, a buffer layer of aluminum nitride (AlN) and aluminum gallium nitride (AlGaN) is formed on the wafer W using TMA, TMG and ammonia.

  Next, a GaN film is formed on the wafer W (S110). The GaN film is a single crystal. The thickness of the GaN film is, for example, 100 nm or more and 10 μm or less.

  When forming the GaN film, the wafer W is rotated at a predetermined rotation speed. The rotation speed is, for example, not less than 500 rpm and not more than 1500 rpm. The temperature of the wafer W is, for example, 500 ° C. to 1200 ° C., preferably 800 ° C. to 1200 ° C., and most preferably 1000 ° C. to 1100 ° C.

  When forming a GaN film, for example, TMG using nitrogen gas as a carrier gas is supplied from the first gas supply path 11. Further, for example, ammonia is supplied from the second gas supply path 12. Further, for example, nitrogen gas is supplied from the third gas supply path 13 as a dilution gas.

  TMG, ammonia, and nitrogen gas using nitrogen gas as carrier gas are mixed in the junction 50 and the mixed gas chamber 300 to generate a mixed gas. The mixed gas is supplied from the mixed gas chamber 300 to the reaction chamber 100 through the shower plate 200.

  The mixed gas is supplied to the surface of the wafer W as a laminar flow in a direction substantially perpendicular to the surface of the wafer W in the reaction chamber 100. The mixed gas supplied to the surface of the wafer W flows toward the outer periphery of the wafer W along the surface of the rotating wafer W. A GaN film is formed on the wafer W by a chemical reaction of the mixed gas.

  Next, an InAlN film is formed on the wafer W without unloading the wafer W from the reaction chamber 100. The InAlN film is a single crystal. The thickness of the InAlN film is, for example, not less than 5 nm and not more than 30 nm. The thickness of the InAlN film is, for example, smaller than the thickness of the GaN film.

  The In composition of the InAlN film is, for example, about 17 atomic%. The In composition indicates the ratio of indium to the group III element in the InAlN film.

  When forming the InAlN film, the wafer W is rotated at a predetermined rotation speed. The rotation speed is, for example, 1600 rpm or more and 1800 rpm or less. The temperature of the wafer W is, for example, 700 ° C. or more and 900 ° C. or less.

  When the InAlN film is formed, for example, TMI using nitrogen gas as a carrier gas is supplied from the first gas supply path 11. In addition, for example, TMA using nitrogen gas as a carrier gas is supplied from the first gas supply path 11. Further, for example, ammonia is supplied from the second gas supply path 12. Further, for example, a nitrogen gas is supplied from the third gas supply path 13 as a dilution gas.

  TMI using nitrogen gas as a carrier gas, TMA using nitrogen gas as a carrier gas, ammonia, and nitrogen gas are mixed to generate a mixed gas. The mixed gas is supplied from the mixed gas chamber 300 to the reaction chamber 100 through the shower plate 200.

  The mixed gas is supplied to the surface of the wafer W as a laminar flow in a direction substantially perpendicular to the surface of the wafer W in the reaction chamber 100. The mixed gas supplied to the surface of the wafer W flows toward the outer periphery of the wafer W along the surface of the rotating wafer W. An InAlN film is formed on the wafer W by a chemical reaction of the mixed gas.

  Next, the wafer W is carried out of the reaction chamber 100 to the outside. With the above-described vapor phase growth method, a GaN film and an InAlN film are continuously formed on a silicon substrate. The GaN film and the InAlN film are epitaxial films.

  Next, the operation and effects of the vapor phase growth apparatus of the first embodiment will be described.

  When a film is grown on the wafer W by vapor phase growth, the quality of the film may be degraded due to unintended incorporation of a substance into the film. For example, the chemical composition of the film shifts from a desired composition, or a defect occurs in the film. Unintended incorporation of the substance may be due to a reaction product containing the substance attached to the inside of the vapor phase growth apparatus during the preceding film growth.

  For example, in the vapor phase growth of an InAlN film, unintended incorporation of gallium into the InAlN film becomes a problem.

  A HEMT using a GaN-based semiconductor achieves high withstand voltage and low on-resistance. The HEMT uses 2DEG induced at a hetero interface between a stacked channel layer and a barrier layer as a current path.

  For example, a GaN film is used for the channel layer, and an AlGaN film is used for the barrier layer. The use of an InAlN film as a barrier layer instead of an AlGaN film has been studied.

  Since the InAlN film has a large spontaneous polarization, the 2DEG concentration at the interface between the InAlN film and the GaN film can be increased. Therefore, a HEMT having a low on-resistance can be realized. Further, by setting the In composition (In / (In + Al)) in the InAlN film to about 17 atomic%, lattice matching with the GaN film can be realized. Therefore, distortion due to lattice mismatch is eliminated, and HEMT reliability is improved.

  Further, the laminated structure of the InAlN film and the GaN film is also expected to be applied to a dielectric mirror used for a surface emitting laser or the like. For application to the above dielectric mirror, it is required that the interface between the GaN film and the InAlN film is clear, that is, the compound composition of the two films changes sharply.

  However, if gallium is unintentionally incorporated into the InAlN film, for example, the 2DEG density at the interface between the InAlN film and the GaN film may decrease, and the electron mobility may decrease. In addition, since a sharp change in the compound composition cannot be obtained, it is difficult to form a good dielectric mirror.

  The cause of the unintended incorporation of Ga into the InAlN film is considered as follows. During the growth of the Ga-containing film before the growth of the InAlN film, a reaction product containing Ga adheres to an upstream portion of the vapor phase growth apparatus. Then, Ga is released from the reaction product containing Ga into the growth atmosphere during the growth of the InAlN film. This Ga is taken into the InAlN film.

  In particular, when an InAlN film is continuously formed on a GaN film, when the GaN film is formed, a reaction product containing gallium attached to the surface of the shower plate 200 or the wall surface 17 of the reaction chamber 100 is formed of InAlN. It is thought that it is taken into the film. As a method of suppressing unintended incorporation of gallium into the InAlN film, for example, it is conceivable to clean the reaction chamber 100 before forming the InAlN film. However, every time an InAlN film is formed, the operation rate of the vapor phase growth apparatus is greatly reduced by cleaning the reaction chamber.

  In the vapor phase growth apparatus of the first embodiment, a first process gas containing a group III element and a second process gas containing a group V element are mixed before being supplied to the reaction chamber 100 to generate a mixed gas. It is possible to do.

  The first process gas and the second process gas are mixed and supplied from the mixed gas chamber 300 to the reaction chamber 100 through the shower plate 200, so that the gas flow rate and the gas density after being released from each gas ejection hole are obtained. Is kept uniform. Therefore, generation of turbulence in the reaction chamber 100 is suppressed.

  In the vapor phase growth apparatus according to the first embodiment, the wafer W can be rotated at a high speed. When the number of the wafers W is one, the wafers can be rotated at high speed. Due to the effect of drawing the mixed gas by the wafer rotating at high speed, generation of turbulence in the reaction chamber 100 is suppressed.

  It is considered that the reaction product is less likely to adhere to the surface of the shower plate 200 by suppressing the generation of the turbulent flow. Further, it is considered that the reaction product hardly adheres to the wall surface 17 of the reaction chamber 100. In addition, it is considered that the generation of the turbulent flow suppresses the reaction products attached to the surface of the shower plate 200 and the wall surface 17 of the reaction chamber 100 from desorbing into the atmosphere.

  Further, by rotating the wafer W at a high speed, the reaction and decomposition of the mixed gas can be limited to the vicinity of the surface of the wafer W. For this reason, it is considered that the adhesion of the reaction product to the surface of the shower plate 200 or the wall surface 17 of the reaction chamber 100 is suppressed.

  Furthermore, in the vapor phase growth apparatus of the first embodiment, the arithmetic average roughness (Ra) of the surface S of the shower plate 200 on the reaction chamber side is 0.05 μm or more and 50 μm or less. If the arithmetic average roughness (Ra) is less than 0.05 μm, the temperature of the surface of the shower plate 200 may decrease. This is because the reflectance of the surface with respect to infrared rays increases, and the amount of heat absorbed by the shower plate 200 decreases. When the temperature of the surface S of the shower plate 200 decreases, the saturated vapor pressure of the mixed gas decreases, and the reaction products tend to adhere.

  By setting the arithmetic average roughness (Ra) of the surface S of the shower plate 200 on the side of the reaction chamber to 0.05 μm or more, the reflectance of the surface S with respect to infrared rays is reduced. Therefore, a decrease in the temperature of the surface S of the shower plate 200 is suppressed, and adhesion of the reaction product to the surface S of the shower plate 200 is suppressed. Further, when the arithmetic average roughness (Ra) exceeds 50 μm, there is a possibility that the reaction product is likely to adhere due to the anchor effect of the unevenness. The arithmetic average roughness (Ra) is more preferably 0.1 μm or more and 10 μm or less.

  FIG. 5 is an explanatory diagram of the effect of the first embodiment. FIG. 5 is a diagram showing the Ga concentration in the InAlN film when the InAlN film is continuously formed. By changing the arithmetic average roughness (Ra) of the surface S of the shower plate 200, the Ga concentration in the InAlN film when a GaN film: 2.0 μm / InAlN film 30 nm is continuously formed without cleaning the reaction chamber 100 Is shown. The distance L between the centers of the adjacent gas ejection holes 22 is 5 mm, and the hole diameter D of the gas ejection holes 22 is 0.5 mm.

  As shown in FIG. 5, when Ra is 0.01 μm, the content of Ga increases beyond the lower limit of detection from two consecutive film formations. When Ra is 0.05 μm, the Ga content is equal to or lower than the lower detection limit up to 20 times of continuous film formation. When Ra is 0.1 μm, 1 μm, and 10 μm, the Ga content is equal to or lower than the lower detection limit even after continuous film formation is performed 200 times.

  When Ra is 25 μm, the content of Ga is equal to or lower than the lower limit of detection up to 50 times of continuous film formation. When Ra is 50 μm, the content of Ga is equal to or lower than the lower detection limit up to 20 times of continuous film formation. When Ra is 100 μm, the content of Ga increases beyond the lower limit from 10 times of continuous film formation.

  The arithmetic average roughness (Ra) of the surface S can be adjusted to a desired value, for example, by controlling the conditions for forming a metal plating layer covering the surface of the shower plate 200.

  Further, the hole diameter D of the gas ejection hole 22 is preferably 0.05 mm or more and 3 mm or less, and more preferably 0.1 mm or more and 2 mm or less. If it is below the above range, there is a possibility that a sufficient process gas cannot be supplied into the reaction chamber 100. If it exceeds the above range, turbulence in the reaction chamber 100 is likely to occur.

  Further, the distance between the wafer W placed on the holder 15 and the shower plate 200 is preferably, for example, not less than 5 cm and not more than 10 cm. Below the above range, the amount of process gas returning from the surface of the wafer W toward the surface of the shower plate 200 increases, and there is a possibility that reaction products attached to the surface of the shower plate 200 increase. If the above range is exceeded, the amount of process gas flowing outside the wafer W increases, and there is a possibility that useless process gas that does not contribute to film formation increases.

  As described above, according to the vapor phase growth apparatus of the first embodiment, adhesion of reaction products to the shower plate 200 and the reaction chamber 100 is suppressed, and a high-quality film can be formed. For example, it becomes possible to form an InAlN film in which unintended incorporation of gallium is suppressed.

(Second embodiment)
The vapor phase growth apparatus of the second embodiment is different from the first embodiment in that the maximum height difference of the surface of the shower plate between the adjacent gas ejection holes is equal to or less than the distance between the centers of the adjacent gas ejection holes. This is the same as the embodiment. Hereinafter, a part of the description overlapping with the first embodiment will not be described.

  The maximum height difference (d in FIG. 6A) of the surface between the adjacent gas ejection holes 22 on the side of the reaction chamber 100 is the distance between the centers of the adjacent gas ejection holes 22 (FIG. 6A). L) The following is true. The position of the end of the gas ejection hole 22 on the side of the reaction chamber 100 is defined as the position where the diameter of the gas ejection hole 22 becomes smallest from the reaction chamber 100 toward the mixed gas chamber 300. That is, the surface between the gas ejection holes 22 includes a tapered portion which is the peripheral edge of the end of the gas ejection holes 22.

  Hereinafter, the hole diameter of the gas ejection hole 22 is represented by the hole diameter (D in FIGS. 6A and 6B) at the end of the gas ejection hole 22 on the side of the reaction chamber 100. In addition, the tapered portion may be formed in all the gas ejection holes 22.

  The distance L between the centers of the adjacent gas ejection holes 22 is, for example, 10 mm or less. The hole diameter D of the gas ejection holes 22 is, for example, 0.05 mm or more and 3 mm or less.

  The aspect ratio of the surface of the shower plate 201 is defined as the maximum height difference d of the shower plate surface with respect to the distance L between the centers of the gas ejection holes 22. As the aspect ratio of the surface of the shower plate 201 increases, the temperature unevenness on the surface of the shower plate 201 increases.

  This is because the radiant heat originating from the high-temperature wafer W causes a shadowed portion to be generated on the surface of the shower plate 201. When a portion that becomes a shadow to the radiant heat is generated on the surface of the shower plate 201, a low-temperature portion is generated on the surface of the shower plate 201. When a low-temperature portion is generated on the surface of the shower plate 201, it is considered that the saturated vapor pressure of the mixed gas decreases near the low-temperature portion, and the reaction product is likely to adhere.

  In the vapor phase growth apparatus of the second embodiment, the aspect ratio of the surface of the shower plate 201 on the side of the reaction chamber 100 is reduced. Therefore, the adhesion of the reaction product to the surface of the shower plate 201 is suppressed.

  In the vapor phase growth apparatus according to the second embodiment, for example, when an InAlN film is continuously formed on a GaN film, gallium on the surface of the shower plate 201 and the wall surface 17 of the reaction chamber 100 during the formation of the GaN film. It is considered that the adhesion of the reaction product containing is suppressed. It is also considered that the reaction product containing gallium is prevented from desorbing into the atmosphere during the formation of the InAlN film.

  FIG. 7 is an explanatory diagram of the effect of the second embodiment. FIG. 7 is a diagram showing the Ga concentration in the InAlN film when the InAlN film is continuously formed. The Ga concentration in the InAlN film when a GaN film: 2.0 μm / 30 nm InAlN film is continuously formed without cleaning the reaction chamber 100 while changing the maximum height difference d of the surface S of the shower plate 201 is shown. The distance L between the centers of the adjacent gas ejection holes 22 is 5 mm, and the hole diameter D of the gas ejection holes 22 is 0.5 mm.

  As shown in FIG. 7, when d = 1L or less, that is, when the maximum height difference d between the gas ejection holes 22 is less than or equal to the distance L between the centers of the adjacent gas ejection holes 22, continuous film formation is performed 200 times. Also, the content of Ga is below the lower limit of detection.

  In the vapor phase growth apparatus of the second embodiment, the distance L between the centers of adjacent gas ejection holes 22 is preferably 10 mm or less from the viewpoint of forming a film having uniform characteristics. L is preferably 1 mm or more and 8 mm or less, more preferably 3 mm or more and 6 mm or less. Below the above range, turbulence in the reaction chamber 100 tends to occur. If the ratio exceeds the above range, the uniformity of the properties of the film decreases.

  As described above, according to the vapor phase growth apparatus of the second embodiment, as in the first embodiment, adhesion of reaction products to the shower plate 201 and the reaction chamber 100 is suppressed, and a high-quality film can be formed. It becomes possible.

(Third embodiment)
The vapor phase growth apparatus of the third embodiment is the same as the first embodiment except that the maximum height difference of the surface of the shower plate between adjacent gas ejection holes is smaller than the diameter of the gas ejection holes. . Hereinafter, a part of the description overlapping with the first embodiment and the second embodiment will be partially omitted.

  FIG. 8 is an enlarged schematic cross-sectional view of a part of the shower plate according to the third embodiment. 8A is a cross section corresponding to the AA 'cross section in FIG. 2, and FIG. 8B is a cross section corresponding to the BB' cross section in FIG.

  As shown in FIGS. 8A and 8B, the shower plate 202 has the same shape in both the AA ′ section and the BB ′ section. The gas ejection holes 22 of the shower plate 202 are chamfered at the end on the reaction chamber 100 side. Due to the chamfering, a maximum height difference (d in FIGS. 8A and 8B) occurs on the surface S between the adjacent gas ejection holes 22.

  The maximum height difference d of the surface S of the shower plate 202 between the adjacent gas ejection holes 22 is smaller than the hole diameter of the gas ejection holes 22 (D in FIGS. 8A and 8B). Therefore, the aspect ratio of the surface S of the shower plate 202 on the side of the reaction chamber 100 is small. Therefore, the adhesion of the reaction product to the surface of the shower plate 202 is suppressed.

  As described above, according to the vapor phase growth apparatus of the third embodiment, as in the first embodiment, adhesion of reaction products to the shower plate 202 and the reaction chamber 100 is suppressed, and a high-quality film can be formed. It becomes possible.

(Fourth embodiment)
The vapor phase growth apparatus of the fourth embodiment is the same as the first embodiment except that it does not have a junction. Hereinafter, a part of the description overlapping with the first embodiment will not be described.

  FIG. 9 is a schematic sectional view of the vapor phase growth apparatus of the fourth embodiment. The vapor phase growth apparatus of the fourth embodiment is, for example, a single-wafer type epitaxial growth apparatus using a metal organic chemical vapor deposition method (MOCVD method).

  The first gas supply path 11, the second gas supply path 12, and the third gas supply path 13 supply a process gas to the mixed gas chamber 300. The mixed gas chamber 300 includes a first gas supply port 20a, a second gas supply port 20b, and a third gas supply port 20c.

  The first gas supply path 11 is connected to a first gas supply port 20a. The second gas supply path 12 is connected to the second gas supply port 20b. The third gas supply path 13 is connected to the third gas supply port 20c. The first gas supply path 11, the second gas supply path 12, and the third gas supply path 13 are separated from each other until reaching the mixed gas chamber 300. In other words, in the vapor phase growth apparatus according to the fourth embodiment, the confluence unit 50 included in the vapor phase growth apparatus according to the first embodiment is not provided.

  The mixed gas chamber 300 is an example of a gas mixing mechanism. The first process gas, the second process gas, and the third process gas are mixed in the mixed gas chamber 300 to generate a mixed gas.

  As described above, according to the vapor phase growth apparatus of the fourth embodiment, as in the first embodiment, the adhesion of reaction products to the shower plate 200 and the reaction chamber 100 is suppressed, and a high-quality film can be formed. It becomes possible.

  The embodiments of the invention have been described with reference to examples. The embodiments described above are merely given as examples, and do not limit the present invention. Also, the components of each embodiment may be appropriately combined.

  In the embodiment, the case where the gas ejection holes 22 are circular has been described as an example, but the gas ejection holes 22 may have other shapes such as an elliptical shape and a rectangular shape.

  In the embodiment, a case has been described as an example in which two types of heaters, an in-heater 24 and an out-heater 26, are provided, but only one type of heater may be used.

  In the embodiment, portions of the vapor phase growth apparatus that are not directly necessary for the description of the present invention are omitted, but the required apparatus configuration and the like of the vapor phase growth apparatus can be appropriately selected and used. In addition, all vapor phase epitaxy apparatuses which include the elements of the present invention and whose design can be appropriately changed by those skilled in the art are included in the scope of the present invention. It is intended that the scope of the invention be defined by the following claims and their equivalents:

15 Holder 19 Rotation drive mechanism 22 Gas ejection hole 50 Merging section 100 Reaction chamber 200 Shower plate 201 Shower plate 202 Shower plate 300 Mixed gas chamber d Maximum height difference D Hole diameter L Distance S Surface W Substrate (wafer)

Claims (5)

A reaction chamber,
A holder provided in the reaction chamber and holding a substrate,
A rotation drive mechanism for rotating the holder,
A gas mixing mechanism for mixing a first gas containing a Lewis acid and a second gas containing a Lewis base to generate a mixed gas;
A plurality of gas ejection holes that are provided between the gas mixing mechanism and the reaction chamber and eject the mixed gas into the reaction chamber; and a surface on the reaction chamber side between the gas ejection holes. A shower plate having an arithmetic average roughness of 0.05 μm or more and 50 μm or less,
A vapor phase growth apparatus comprising:   The vapor phase growth apparatus according to claim 1, wherein the arithmetic average roughness of the surface is 0.1 µm or more and 10 µm or less.   The vapor phase growth apparatus according to claim 1, wherein a maximum height difference of the surface between the adjacent gas ejection holes is equal to or less than a distance between centers of the adjacent gas ejection holes.   The vapor phase growth apparatus according to claim 3, wherein the maximum height difference is smaller than the diameter of the gas ejection hole.   5. The gas phase growth apparatus according to claim 1, wherein the gas mixing mechanism includes a mixed gas chamber filled with the mixed gas, and the gas ejection hole is connected to the mixed gas chamber. 6. .

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