Vapor phase growth device and vapor phase growth method

Abstract

PURPOSE: To provide a vapor phase growth device capable of reducing defects in a film.CONSTITUTION: A vapor phase growth device includes: a reaction chamber; a holder disposed within the reaction chamber, for placing a substrate thereon; a source gas flow path for supplying a first source gas containing silicon and chlorine into the reaction chamber; a purge gas flow path for supplying a purge gas containing chlorine and hydrogen into the reaction chamber; and a control unit for controlling the supply of the first source gas and the purge gas into the reaction chamber. The control unit performs control such that a ratio of a sum of a second amount of substance which is the amount of substance of chlorine contained in the first source gas and a third amount of substance which is the amount of substance of chlorine contained in the purge gas to a first amount of substance which is the amount of substance of silicon contained in the first source gas is 30 or greater during a first period, and the control unit performs control such that the flow rate of the first source gas increases during a second period after the first period.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vapor phase growth apparatus and a vapor phase growth method for forming a film by supplying a gas to a substrate. [Background technology]

[0002] One method for forming high-quality semiconductor films is epitaxial growth, which involves forming a single-crystal film on the surface of a substrate by vapor phase growth. In a vapor phase growth apparatus using epitaxial growth, the substrate is placed on a holder in a reaction chamber maintained at normal or reduced pressure.

[0003] While the substrate is heated, a process gas containing the film raw material is supplied to the reaction chamber through a gas inlet at the top of the chamber, causing a thermal reaction of the process gas on the surface of the substrate, resulting in the formation of an epitaxial single crystal film on the surface of the substrate.

[0004] Defects may occur on the surface of the formed epitaxial single crystal film, such as pits or bumps. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-117907 [Patent Document 2] International Publication No. 2022 / 130926 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a vapor phase growth apparatus and a vapor phase growth method that can reduce defects in a film. [Means for solving the problem]

[0007] a first amount of substance of silicon contained in the first source gas supplied to the reaction chamber per unit time; a purge gas flow path for supplying a purge gas containing chlorine and hydrogen into the reaction chamber; and a control unit for controlling the supply of the first source gas and the purge gas into the reaction chamber, wherein the control unit controls the flow rates of the first source gas and the purge gas into the reaction chamber during a first period so that a ratio ((second amount of substance+third amount of substance) / first amount of substance) of the sum of a second amount of substance of chlorine contained in the first source gas supplied to the reaction chamber per unit time and a third amount of substance of chlorine contained in the purge gas supplied to the reaction chamber per unit time, to a first amount of substance of silicon contained in the first source gas supplied to the reaction chamber per unit time, is 30 or greater; and the control unit controls the flow rate of the first source gas to increase during a second period after the first period.

[0008] In the vapor phase growth apparatus of the above aspect, it is preferable that the control unit further controls the supply of a second source gas containing carbon into the reaction chamber, and that the control unit controls the supply of the second source gas into the reaction chamber to start after the first period.

[0009] In the vapor phase growth apparatus of the above aspect, it is preferable that the control unit controls the ratio of a fourth amount of substance, which is the amount of carbon contained in the second source gas supplied to the reaction chamber per unit time, to the first amount of substance (fourth amount of substance / first amount of substance) to be 1.2 or less.

[0010] In the vapor phase growth apparatus of the above aspect, it is preferable that the control unit controls the ratio of the second amount of substance to the first amount of substance (second amount of substance / first amount of substance) to be constant during the first period and the second period.

[0011] In the vapor phase growth apparatus of the above aspect, it is preferable that the control unit controls the amount of the third substance to be constant during the first period and the second period.

[0012] A vapor phase growth method according to one embodiment of the present invention is a vapor phase growth method for forming a silicon carbide film on a substrate placed on a holder provided in a reaction chamber, the method comprising: supplying into the reaction chamber, during a first period, a first source gas containing silicon and chlorine and a purge gas containing chlorine and hydrogen, such that a ratio ((second amount of substance+third amount of substance) / first amount of substance) of the sum of a second amount of substance, which is the amount of substance of chlorine contained in the first source gas supplied to the reaction chamber per unit time, and a third amount of substance, which is the amount of substance of chlorine in the purge gas supplied to the reaction chamber per unit time, to a first amount of substance, which is the amount of substance of silicon contained in the first source gas supplied to the reaction chamber per the unit time, is 30 or greater; and increasing a flow rate of the first source gas supplied to the reaction chamber during a second period following the first period.

[0013] In the vapor phase growth method of the above aspect, it is preferable to start supplying a second source gas containing carbon into the reaction chamber after the first period.

[0014] In the vapor phase growth method of the above aspect, it is preferable that the ratio of a fourth amount of substance, which is the amount of carbon contained in the second source gas supplied to the reaction chamber per unit time, to the first amount of substance (fourth amount of substance / first amount of substance) is 1.2 or less.

[0015] In the vapor phase growth method of the above aspect, it is preferable that the ratio of the second amount of substance to the first amount of substance (second amount of substance / first amount of substance) is constant during the first period and the second period.

[0016] In the vapor phase growth method of the above aspect, it is preferable that the amount of the third substance is constant during the first period and the second period. [Effects of the Invention]

[0017] According to the present invention, it is possible to realize a vapor phase growth apparatus and a vapor phase growth method that can reduce defects in a film. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic cross-sectional view of a vapor phase growth apparatus according to a first embodiment. [Figure 2] FIG. 2 is an enlarged schematic cross-sectional view of a part of a gas inlet portion of the vapor phase growth apparatus of the first embodiment. [Figure 3] FIG. 2 is an enlarged schematic cross-sectional view of a part of a gas inlet portion of the vapor phase growth apparatus of the first embodiment. [Figure 4] FIG. 2 is an explanatory diagram of control by a control circuit in the vapor phase growth apparatus of the first embodiment. [Figure 5] FIG. 2 is an explanatory diagram of control by a control circuit in the vapor phase growth apparatus of the first embodiment. [Figure 6] FIG. 2 is an explanatory diagram of control by a control circuit in the vapor phase growth apparatus of the first embodiment. [Figure 7] 1A to 1C are explanatory diagrams illustrating the operation and effect of the vapor phase growth apparatus and vapor phase growth method of the first embodiment. [Figure 8] 1A to 1C are explanatory diagrams illustrating the operation and effect of the vapor phase growth apparatus and vapor phase growth method of the first embodiment. [Figure 9] FIG. 1 is an explanatory diagram of a vapor phase growth apparatus and a vapor phase growth method according to a first embodiment. [Figure 10] FIG. 1 is an explanatory diagram of a vapor phase growth apparatus and a vapor phase growth method according to a first embodiment. [Figure 11] FIG. 1 is an explanatory diagram of a vapor phase growth apparatus and a vapor phase growth method according to a first embodiment. [Figure 12] FIG. 4 is a schematic cross-sectional view of a vapor phase growth apparatus according to a second embodiment. [Figure 13] FIG. 6 is an explanatory diagram of control by a control circuit in a vapor phase growth apparatus according to a second embodiment. [Figure 14] FIG. 6 is an explanatory diagram of control by a control circuit in a vapor phase growth apparatus according to a second embodiment. [Figure 15] FIG. 6 is an explanatory diagram of control by a control circuit in a vapor phase growth apparatus according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] In this specification, the same or similar components may be denoted by the same reference numerals.

[0021] In this specification, the direction of gravity when the vapor deposition apparatus is set up 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 relative to a reference, and "lower" means the direction of gravity relative to a reference. "Upper" means a position in the opposite direction to the direction of gravity relative to a reference, and "upper" means the opposite direction to the direction of gravity relative to a reference. Furthermore, "vertical direction" means the direction of gravity.

[0022] In addition, in this specification, the term "process gas" is a general term for gases used to form a film, and is a concept that includes, for example, source gas, assist gas, dopant gas, carrier gas, purge gas, and mixtures thereof.

[0023] (First embodiment) A vapor phase growth apparatus according to a first embodiment includes a reaction chamber, a holder disposed within the reaction chamber for supporting a substrate, a source gas flow path for supplying a first source gas containing silicon and chlorine into the reaction chamber, a purge gas flow path for supplying a purge gas containing chlorine and hydrogen into the reaction chamber, and a controller for controlling the supply of the first source gas and the purge gas into the reaction chamber. The controller controls the flow rates of the first source gas and the purge gas into the reaction chamber during a first period of time so that a ratio ((second amount of substance + third amount of substance) / first amount of substance) of the sum of a second amount of substance, which is the amount of substance of chlorine contained in the first source gas supplied per unit time to a first amount of substance, which is the amount of substance of silicon contained in the first source gas supplied per unit time to the reaction chamber, is 30 or greater. The controller controls the flow rate of the first source gas to increase during a second period of time following the first period of time.

[0024] 1 is a schematic cross-sectional view of a vapor phase growth apparatus according to a first embodiment. The vapor phase growth apparatus 100 according to the first embodiment is, for example, a single-wafer type epitaxial growth apparatus that epitaxially grows a single-crystal SiC film (silicon carbide film) on a single-crystal SiC substrate (silicon carbide substrate). The vapor phase growth apparatus 100 according to the first embodiment is a vertical type vapor phase growth apparatus in which a process gas is supplied vertically to the surface of the SiC substrate.

[0025] The vapor phase growth apparatus 100 of the first embodiment includes a reaction chamber 10, a gas introduction unit 11, and a control circuit (control unit) 12. The reaction chamber 10 includes a susceptor 14 (holder), a rotor 16, a rotation shaft 18, a rotation drive mechanism 20, a first heater 22, a reflector 28, support columns 30, a fixed base 32, a fixed shaft 34, a hood 40, a second heater 42, and a gas outlet 44. The gas introduction unit 11 includes a first source gas region 51, a second source gas region 52, a first purge gas region 53, a second purge gas region 54, a rectifying plate 60, partition plates 61, 62, and 63, a top plate 64, a first source gas conduit 71, a second source gas conduit 72, a first purge gas conduit 73, and a second purge gas conduit 74.

[0026] The vapor phase growth apparatus 100 of the first embodiment includes a first source gas supply pipe 81, a second source gas supply pipe 82, a first purge gas supply pipe 83, a second purge gas supply pipe 84, a first mass flow controller MFC1, a second mass flow controller MFC2, a third mass flow controller MFC3, a fourth mass flow controller MFC4, a first valve V1, a second valve V2, a third valve V3, and a fourth valve V4.

[0027] The first source gas supply pipe 81, the first source gas region 51, and the first source gas conduit 71 form a first source gas flow path. The first source gas flow path supplies the first source gas SG1 to the reaction chamber 10.

[0028] The second source gas supply pipe 82, the second source gas region 52, and the second source gas conduit 72 form a second source gas flow path. The second source gas flow path supplies the second source gas SG2 to the reaction chamber 10.

[0029] The first source gas flow path and the second source gas flow path are examples of a source gas flow path.

[0030] The first purge gas supply pipe 83, the first purge gas region 53, and the first purge gas conduit 73 form a first purge gas flow path. The second purge gas supply pipe 84, the second purge gas region 54, and the second purge gas conduit 74 form a second purge gas flow path.

[0031] The first purge gas flow path and the second purge gas flow path supply the purge gas PG to the reaction chamber 10. The first purge gas flow path and the second purge gas flow path are examples of purge gas flow paths.

[0032] A first valve V1 and a first mass flow controller MFC1 are provided in a first source gas supply pipe 81. The first valve V1 has a function of switching between starting and stopping the introduction of a first source gas SG1 introduced into the first source gas supply pipe 81. The first mass flow controller MFC1 has a function of adjusting the flow rate of the first source gas SG1 introduced into the first source gas supply pipe 81 to a predetermined amount.

[0033] The second valve V2 and the second mass flow controller MFC2 are provided in the second source gas supply pipe 82. The second valve V2 has a function of switching between starting and stopping the introduction of the second source gas SG2 introduced into the second source gas supply pipe 82. The second mass flow controller MFC2 has a function of adjusting the flow rate of the second source gas SG2 introduced into the second source gas supply pipe 82 to a predetermined amount.

[0034] The third valve V3 and the third mass flow controller MFC3 are provided in the first purge gas supply pipe 83. The third valve V3 has a function of switching between starting and stopping the introduction of the purge gas PG introduced into the first purge gas supply pipe 83. The third mass flow controller MFC3 has a function of adjusting the flow rate of the purge gas PG introduced into the first purge gas supply pipe 83 to a predetermined amount.

[0035] A fourth valve V4 and a fourth mass flow controller MFC4 are provided in the second purge gas supply pipe 84. The fourth valve V4 has a function of switching between starting and stopping the introduction of the purge gas PG introduced into the second purge gas supply pipe 84. The fourth mass flow controller MFC4 has a function of adjusting the flow rate of the purge gas PG introduced into the second purge gas supply pipe 84 to a predetermined amount.

[0036] The first valve V1, the second valve V2, the third valve V3, the fourth valve V4, the first mass flow controller MFC1, the second mass flow controller MFC2, the third mass flow controller MFC3, and the fourth mass flow controller MFC4 are controlled by a control circuit 12.

[0037] The reaction chamber 10 is made of, for example, stainless steel. The reaction chamber 10 has a cylindrical wall. In the reaction chamber 10, a SiC film is formed on a wafer W. The wafer W is an example of a substrate.

[0038] The susceptor 14 is provided in the reaction chamber 10. A wafer W can be placed on the susceptor 14. The susceptor 14 may have an opening in the center. The susceptor 14 is an example of a holder.

[0039] The susceptor 14 is made of a highly heat-resistant material such as SiC, carbon, or carbon coated with SiC or TaC.

[0040] The susceptor 14 is fixed to the upper part of a rotor 16. The rotor 16 is fixed to a rotation shaft 18. The susceptor 14 is indirectly fixed to the rotation shaft 18.

[0041] The rotation shaft 18 can be rotated by a rotation drive mechanism 20. The rotation drive mechanism 20 can rotate the rotation shaft 18 to rotate the susceptor 14. By rotating the susceptor 14, the wafer W placed on the susceptor 14 can be rotated.

[0042] The rotation drive mechanism 20 can rotate the wafer W at a rotation speed of, for example, 300 rpm or more and 3000 rpm or less. The rotation drive mechanism 20 is composed of, for example, a motor and a bearing.

[0043] The first heater 22 is provided below the susceptor 14. The first heater 22 is provided inside the rotating body 16. The first heater 22 heats the wafer W held on the susceptor 14 from below. The first heater 22 is, for example, a resistance heater. The first heater 22 is, for example, a disk-shaped heater having a comb-shaped pattern. The first heater 22 may be divided into an outer peripheral heater (not shown) that heats the outer periphery of the wafer and an inner peripheral heater (not shown) that heats the inner periphery of the wafer.

[0044] The reflector 28 is provided below the first heater 22. The first heater 22 is provided between the reflector 28 and the susceptor 14.

[0045] The reflector 28 reflects heat radiated downward from the first heater 22, thereby improving the heating efficiency of the wafer W. The reflector 28 also prevents members below the reflector 28 from being heated. The reflector 28 has, for example, a disk shape. The reflector 28 is formed of a highly heat-resistant material, for example, carbon coated with SiC.

[0046] The reflector 28 is fixed to a fixed base 32 by, for example, a plurality of support columns 30. The fixed base 32 is supported by, for example, a fixed shaft 34.

[0047] A push-up pin (not shown) is provided inside the rotor 16 in order to detach the susceptor 14 from the rotor 16. The push-up pin penetrates, for example, the reflector 28 and the first heater 22.

[0048] The second heater 42 is provided between the hood 40 and the inner wall of the reaction chamber 10. The second heater 42 heats the wafer W held on the susceptor 14 from above. By heating the wafer W with the second heater 42 in addition to the first heater 22, it is possible to heat the wafer W to a temperature required for growing a SiC film, for example, a temperature of 1500°C or higher. The second heater 42 is, for example, a resistance heater.

[0049] The hood 40 has, for example, a cylindrical shape. The hood 40 has a function of preventing the process gas from coming into contact with the second heater 42. The hood 40 is formed of a highly heat-resistant material, for example, carbon coated with SiC.

[0050] The gas exhaust port 44 is provided at the bottom of the reaction chamber 10. The gas exhaust port 44 exhausts excess reaction products produced after the source gas reacts on the surface of the wafer W and excess process gas to the outside of the reaction chamber 10. The gas exhaust port 44 is connected to, for example, a vacuum pump (not shown).

[0051] Furthermore, a wafer inlet / outlet and a gate valve (not shown) are provided in the reaction chamber 10. The wafer inlet / outlet and the gate valve allow the wafer W to be loaded into and unloaded from the reaction chamber 10.

[0052] The gas inlet 11 is provided above the reaction chamber 10 .

[0053] A first source gas SG1 is introduced into the first source gas region 51 from a first source gas supply pipe 81. The first source gas region 51 is provided between the first purge gas region 53 and the top plate 64.

[0054] A second source gas SG2 is introduced into the second source gas region 52 from a second source gas supply pipe 82. The second source gas region 52 is provided between the second purge gas region 54 and the first purge gas region 53.

[0055] A purge gas PG is introduced into the first purge gas region 53 from a first purge gas supply pipe 83. The first purge gas region 53 is provided between the second source gas region 52 and the first source gas region 51.

[0056] A purge gas PG is introduced into the second purge gas region from a second purge gas supply pipe 84. The second purge gas region is provided between the second source gas region 52 and the reaction chamber .

[0057] The straightening plate 60 is provided between the reaction chamber 10 and the second purge gas region 54. The straightening plate 60 has a plurality of holes 60a and a plurality of holes 60b.

[0058] The partition plate 61 is provided between the second purge gas region 54 and the second source gas region 52. The partition plate 61 has a plurality of holes 61a.

[0059] The partition plate 62 is provided between the second source gas region 52 and the first purge gas region 53. The partition plate 62 has a plurality of holes 62a.

[0060] The partition plate 63 is provided between the first purge gas region 53 and the first source gas region 51. The partition plate 63 has a hole 63a.

[0061] The top plate 64 is provided above the first source gas region 51 .

[0062] The first source gas SG1 is a source gas of silicon (Si). The first source gas SG1 contains silicon (Si) and chlorine (Cl). The first source gas SG1 is, for example, silane (SiH4) or silane chloride (SiH 4-n Cl n(n=1 to 4). The first source gas SG1 includes, for example, hydrogen chloride (HCl). The first source gas SG1 includes, for example, hydrogen gas (H). The first source gas SG1 is, for example, a mixed gas of silane (SiH), hydrogen chloride (HCl), and hydrogen gas (H).

[0063] Hydrogen chloride (HCl) is an assist gas that suppresses clustering of silicon and also has the function of etching by-products containing silicon that accumulate in the flow path of the first source gas SG1.

[0064] Hydrogen gas (H2) is a carrier gas. Argon gas (Ar), for example, can also be used as the carrier gas.

[0065] The second source gas SG2 is a carbon (C) source gas. The second source gas SG2 contains carbon (C). The second source gas SG2 contains, for example, a hydrocarbon. The second source gas SG2 is, for example, a mixed gas of propane (C3H8) and hydrogen gas (H2).

[0066] The second source gas SG2 includes, for example, an n-type impurity dopant gas, such as nitrogen gas.

[0067] The purge gas PG has a function of preventing the first source gas SG1 supplied to the reaction chamber 10 from circulating into the first purge gas conduit 73 from the reaction chamber 10 side. In addition, the purge gas PG has a function of preventing the second source gas SG2 supplied to the reaction chamber 10 from circulating into the second purge gas conduit 74 from the reaction chamber 10 side.

[0068] The purge gas PG includes chlorine (Cl) and hydrogen (H). The purge gas PG includes, for example, hydrogen chloride (HCl). The purge gas PG includes, for example, hydrogen gas (H). The purge gas PG is, for example, a mixed gas of hydrogen chloride (HCl) and hydrogen gas (H).

[0069] Instead of hydrogen gas (H2), for example, argon gas (Ar) can be used.

[0070] The atomic concentration of chlorine in the purge gas PG is, for example, lower than the atomic concentration of chlorine in the first source gas SG1. The atomic concentration of chlorine in the purge gas PG is, for example, one-fifth or less of the atomic concentration of chlorine in the first source gas SG1. The purge gas PG introduced into the first purge gas supply pipe 83 and the purge gas PG introduced into the second purge gas supply pipe 84 may have different gas mixture ratios and different gas species.

[0071] 2 is an enlarged schematic cross-sectional view of a part of the gas inlet portion of the vapor phase growth apparatus of the first embodiment, including a first source gas conduit 71 and a first purge gas conduit 73.

[0072] The first source gas conduit 71 supplies a first source gas SG1 to the reaction chamber. The first source gas conduit 71 is inserted into the holes 60a, 61a, 62a, and 63a. The first source gas conduit 71 penetrates the straightening plate 60 and the partition plates 61, 62, and 63.

[0073] The first source gas conduit 71 has an annular flange 71a at its upper end. The first source gas conduit 71 is detachable from the partition plate 63. The first source gas conduit 71 supports its own weight by having the flange 71a placed on the partition plate 63.

[0074] The first purge gas conduit 73 supplies a purge gas PG to the reaction chamber 10. The first purge gas conduit 73 is inserted into the holes 60a, 61a, and 62a. The first purge gas conduit 73 penetrates the straightening plate 60 and the partition plates 61 and 62.

[0075] The first purge gas conduit 73 has an annular flange 74a at its upper end. The first purge gas conduit 73 is detachable from the partition plate 62. The first purge gas conduit 73 supports its own weight by having the flange 74a placed on the partition plate 62.

[0076] The first source gas conduit 71 is inserted inside the first purge gas conduit 73. The first purge gas conduit 73 and the first source gas conduit 71 are spaced apart. There is a gap between the first purge gas conduit 73 and the first source gas conduit 71. The gap between the first purge gas conduit 73 and the first source gas conduit 71 serves as a flow path for the purge gas PG.

[0077] 3 is an enlarged schematic cross-sectional view of a portion of the gas inlet section of the vapor phase growth apparatus of the first embodiment, including the second source gas conduit 72 and the second purge gas conduit 74.

[0078] The second source gas conduit 72 supplies a second source gas SG2 to the reaction chamber. The second source gas conduit 72 is inserted into the holes 60a and 61a. The second source gas conduit 72 penetrates the rectifying plate 60 and the partition plate 61.

[0079] The second source gas conduit 72 has an annular flange 72a at its upper end. The second source gas conduit 72 is detachable from the partition plate 61. The second source gas conduit 72 supports its own weight by having the flange 72a placed on the partition plate 61.

[0080] The second purge gas conduit 74 supplies the purge gas PG to the reaction chamber 10. The second purge gas conduit 74 is inserted into the hole 60a. The second purge gas conduit 74 penetrates the straightening plate 60.

[0081] The second purge gas conduit 74 has an annular flange 74a at its upper end. The second purge gas conduit 74 is detachable from the straightening plate 60. The second purge gas conduit 74 supports its own weight by having the flange 74a placed on the straightening plate 60.

[0082] The second source gas conduit 72 is inserted inside the second purge gas conduit 74. The second purge gas conduit 74 and the second source gas conduit 72 are spaced apart. The space between the second purge gas conduit 74 and the second source gas conduit 72 forms a flow path for the purge gas PG. The holes 60b in the rectifying plate 60 also form a flow path for the purge gas PG.

[0083] The first source gas conduit 71, the second source gas conduit 72, the first purge gas conduit 73, and the second purge gas conduit 74 are made of a highly heat-resistant material, such as carbon coated with SiC. The rectifying plate 60 and the partition plates 61, 62, and 63 are also made of a highly heat-resistant material, such as carbon coated with SiC.

[0084] The control circuit 12 has a function of controlling the supply of a first source gas SG1, a second source gas SG2, and a purge gas PG into the reaction chamber 10.

[0085] The control circuit 12 controls the first valve V1, the second valve V2, the third valve V3, the fourth valve V4, the first mass flow controller MFC1, the second mass flow controller MFC2, the third mass flow controller MFC3, and the fourth mass flow controller MFC4. The control circuit 12 is an example of a control unit.

[0086] The control circuit 12 controls, for example, the opening and closing of a first valve V1, a second valve V2, a third valve V3, and a fourth valve V4. The control circuit 12 transmits gas flow rate command values to, for example, a first mass flow controller MFC1, a second mass flow controller MFC2, a third mass flow controller MFC3, and a fourth mass flow controller MFC4.

[0087] The control circuit 12 controls the flow rate of the first source gas SG1, for example, by sending a command value for the flow rate of the first source gas SG1 to the first mass flow controller MFC1. The control circuit 12 controls the flow rate of the second source gas SG2, for example, by sending a command value to the second mass flow controller MFC2. The control circuit 12 controls the flow rate of the purge gas PG, for example, by sending a command value to the third mass flow controller MFC3. The control circuit 12 controls the flow rate of the purge gas PG, for example, by sending a command value to the fourth mass flow controller MFC4.

[0088] The control circuit 12 is, for example, an electronic circuit and includes, for example, hardware and software.

[0089] The control circuit 12 includes, for example, a central processing unit (CPU). The control circuit 12 includes, for example, a storage device. The storage device included in the control circuit 12 is, for example, a semiconductor memory, a solid state device (SSD), or a hard disk.

[0090] 4 is an explanatory diagram of control by the control circuit of the vapor phase growth apparatus of the first embodiment. Fig. 4 is a diagram showing the change over time in the flow rate of the process gas supplied to the reaction chamber 10 of the vapor phase growth apparatus 100. The flow rate of the process gas is controlled by the control circuit 12.

[0091] When forming a SiC film on the wafer W, the control circuit 12 controls the supply of the first source gas SG1 and the purge gas PG to the reaction chamber 10 to start at time t0. Specifically, for example, the control circuit 12 sends command signals to the first valve V1, the third valve V3, and the fourth valve V4 at time t0 to open the first valve V1, the third valve V3, and the fourth valve V4, thereby starting the supply of the first source gas SG1 and the purge gas PG to the reaction chamber 10.

[0092] The control circuit 12 controls the flow rates of the first source gas SG1 and the purge gas PG to be desired flow rates. Specifically, for example, the control circuit 12 adjusts the apertures of the first mass flow controller MFC1, the third mass flow controller MFC3, and the fourth mass flow controller MFC4 by sending command signals to the first mass flow controller MFC1, the third mass flow controller MFC3, and the fourth mass flow controller MFC4, thereby controlling the flow rates of the first source gas SG1 and the purge gas PG to be desired flow rates. Note that, hereinafter, the flow rate of the purge gas PG refers to the sum of the flow rates of the purge gas PG supplied from the first purge gas supply pipe 83 and the second purge gas supply pipe 84.

[0093] The control circuit 12 controls the flow rates of the first source gas SG1 and the purge gas so that they are constant, for example, from time t0 to time t1. The period from time t0 to time t1 is referred to as an initial period. The initial period is an example of a first period.

[0094] At time t1, the control circuit 12 controls so that the supply of the second source gas SG2 to the reaction chamber 10 is started. Specifically, for example, at time t1, the control circuit 12 sends a command signal to the second valve V2 to open the second valve V2 and start the supply of the second source gas SG2 to the reaction chamber 10.

[0095] The control circuit 12 controls the flow rates of the first source gas SG1 and the second source gas SG2 to increase, for example, from time t1 to time t2. The control circuit 12 also controls the flow rate of the purge gas PG to be constant, for example, from time t1 to time t2. The period from time t1 to time t2 is referred to as a flow rate increase period. The flow rate increase period is an example of a second period.

[0096] The flow increase period is a period following the initial period, and the flow increase period and the initial period are consecutive.

[0097] After time t2, the control circuit 12 controls the flow rates of the first source gas SG1, the second source gas SG2, and the purge gas so that they are constant. The period after time t2 is referred to as a constant flow rate period.

[0098] The constant flow rate period is the period following the increased flow rate period. The constant flow rate period and the increased flow rate period are continuous.

[0099] 5 is an explanatory diagram of control by the control circuit of the vapor phase growth apparatus of the first embodiment. Fig. 5 is a diagram showing the time changes in the amount of silicon (Si) and the amount of chlorine (Cl) per unit time in the process gas supplied to the reaction chamber 10 of the vapor phase growth apparatus 100. The amount of silicon (Si) and the amount of chlorine (Cl) per unit time are controlled by the control circuit 12.

[0100] In the initial period, the control circuit 12 controls the first amount of silicon (Si SG1 ), the second amount of chlorine (Cl SG1 ), the third amount of substance (Cl PG ) is controlled to be constant.

[0101] The first amount of substance (Si SG1 ) can be calculated from the flow rate of the first source gas SG1 and the atomic concentration of silicon contained in the first source gas SG1. SG1 ) can be calculated from the flow rate of the first source gas SG1 and the atomic concentration of chlorine contained in the first source gas SG1. PG ) can be calculated from the flow rate of the purge gas PG and the atomic concentration of chlorine contained in the purge gas PG.

[0102] If the atomic concentration of silicon contained in the first source gas SG1 and the atomic concentration of chlorine contained in the first source gas SG1 are constant, and the flow rate of the first source gas SG1 is kept constant in the initial period as shown in FIG. 4, the first amount of substance (Si SG1 ) and the second amount of substance (Cl SG1 ) is constant. In this case, the first amount of substance (Si SG1 ) to the second amount of substance (Cl SG1 ) ratio (amount of second substance / amount of first substance) remains constant.

[0103] For example, if the atomic concentration of chlorine contained in the purge gas PG is constant, as shown in FIG. 4, and the flow rate of the purge gas PG is kept constant, the third amount of substance (Cl PG ) becomes constant.

[0104] During the flow rate increasing period, the control circuit 12 controls the flow rate of the first substance (Si SG1 ) and the second amount of substance (Cl SG1 ) is increased. In addition, the control circuit 12 controls the amount of the third substance (Cl PG ) is controlled to be constant.

[0105] If the atomic concentration of silicon contained in the first source gas SG1 and the atomic concentration of chlorine contained in the first source gas SG1 are constant, then if the flow rate of the first source gas SG1 is increased as shown in FIG. 4 during the flow rate increase period, the first substance amount (Si SG1 ) and the second amount of substance (Cl SG1 In this case, the first amount of substance (Si SG1 ) to the second amount of substance (Cl SG1 ) ratio (amount of second substance / amount of first substance) is kept constant.

[0106] For example, if the atomic concentration of chlorine contained in the purge gas PG is constant, and the flow rate of the purge gas PG is kept constant during the flow rate increase period as shown in FIG. 4, the third amount of substance (Cl PG ) becomes constant.

[0107] The control circuit 12 controls the flow rate of, for example, a first substance amount (Si SG1 ), the second amount of substance (Cl SG1 ), and the third amount of substance (Cl PG ) is controlled to be constant.

[0108] If the atomic concentration of silicon contained in the first source gas SG1 and the atomic concentration of chlorine contained in the first source gas SG1 are constant, and the flow rate of the first source gas SG1 is kept constant as shown in FIG. 4, the first amount of substance (Si SG1 ) and the second amount of substance (Cl SG1 ) is constant. In this case, the first amount of substance (Si SG1 ) to the second amount of substance (Cl SG1 ) ratio (amount of second substance / amount of first substance) is kept constant.

[0109] For example, if the atomic concentration of chlorine contained in the purge gas PG is constant, and the flow rate of the purge gas PG is kept constant as shown in FIG. 4, the third amount of substance (Cl PG ) becomes constant.

[0110] FIG. 6 is an explanatory diagram of control by the control circuit of the vapor phase growth apparatus of the first embodiment. SG1 ) to the second amount of substance (Cl SG1 ) and the third amount of substance (Cl PG 1 shows the time change in the ratio ((second amount of substance+third amount of substance) / first amount of substance) of the sum of the second amount of substance and the third amount of substance. ((second amount of substance+third amount of substance) / first amount of substance) is controlled by control circuit 12.

[0111] In the initial period, the control circuit 12 controls the first amount of substance (Si SG1 ) to the second amount of substance (Cl SG1 ) and the third amount of substance (Cl PGThe ratio of the sum of the second amount of substance and the third amount of substance ((second amount of substance + third amount of substance) / first amount of substance) is controlled to be 30 or more. (Second amount of substance + third amount of substance) / first amount of substance is (Cl SG1 +Cl PG ) / Si SG1 It can be written as:

[0112] Control circuit 12 controls the flow rates of first source gas SG1 and purge gas PG in consideration of the atomic concentrations of silicon and chlorine contained in first source gas SG1 and the atomic concentration of chlorine contained in purge gas PG, thereby making it possible to set (second amount of substance+third amount of substance) / first amount of substance to 30 or more. (second amount of substance+third amount of substance) / first amount of substance is, for example, 30 or more and 200 or less.

[0113] By controlling the flow rates of the first source gas SG1 and the purge gas PG as shown in Fig. 4, the (second amount of substance + third amount of substance) / first amount of substance is kept constant during the initial period as shown in Fig. 6. Also, by controlling the flow rates of the first source gas SG1 and the purge gas PG as shown in Fig. 4, the (second amount of substance + third amount of substance) / first amount of substance is reduced during the flow rate increase period as shown in Fig. 6. Also, by controlling the flow rates of the first source gas SG1 and the purge gas PG as shown in Fig. 4, the (second amount of substance + third amount of substance) / first amount of substance is kept constant during the constant flow rate period as shown in Fig. 6.

[0114] The control circuit 12 controls, for example, the first amount of substance (Si SG1 ) which is the amount of carbon contained in the second source gas SG2 supplied to the reaction chamber 10 per unit time, SG2 The flow rates of the first source gas SG1 and the second source gas SG2 are controlled so that the ratio (amount of the fourth substance / amount of the first substance) is 1.2 or less.

[0115] The fourth amount of substance (C SG2 ) can be calculated from the flow rate of the second source gas SG2 and the atomic concentration of carbon contained in the second source gas SG2.

[0116] Next, a vapor phase growth method according to a first embodiment will be described. The vapor phase growth method according to the first embodiment is a vapor phase growth method for forming a silicon carbide film on a substrate placed on a holder provided in a reaction chamber, in which a first source gas containing silicon and chlorine and a purge gas containing chlorine and hydrogen are supplied into the reaction chamber during a first period so that the ratio ((second amount of substance+third amount of substance) / first amount of substance) of the sum of a second amount of substance which is the amount of substance of chlorine contained in the first source gas supplied per unit time to a first amount of substance which is the amount of substance of silicon contained in the first source gas supplied per unit time to a third amount of substance which is the amount of substance of chlorine in the purge gas supplied per unit time to the reaction chamber is 30 or more, and the flow rate of the first source gas supplied into the reaction chamber during a second period following the first period is increased.

[0117] The vapor phase growth method of the first embodiment uses a vapor phase growth apparatus 100 shown in Fig. 1. Hereinafter, an example will be described in which a single crystal SiC film 13 (silicon carbide film) is formed on the surface of a wafer W of single crystal SiC.

[0118] The first source gas SG1 contains silicon and chlorine, the second source gas SG2 contains carbon, and the purge gas PG contains chlorine and hydrogen.

[0119] The following description will be given taking as an example a case where the first source gas SG1 is a mixed gas of silane (SiH4), hydrogen chloride (HCl), and hydrogen gas (H2), the second source gas SG2 is a mixed gas of propane (C3H8) and hydrogen gas (H2), and the purge gas PG is a mixed gas of hydrogen chloride (HCl) and hydrogen gas (H2).

[0120] The atomic concentration of silicon in the first source gas SG1, the atomic concentration of chlorine in the first source gas SG1, the atomic concentration of carbon in the second source gas SG2, and the atomic concentration of chlorine in the purge gas PG are each kept constant.

[0121] First, the susceptor 14 on which the wafer W is placed is carried into the reaction chamber 10. The wafer W is made of single crystal SiC.

[0122] Next, the wafer W is rotated at a rotation speed of 300 rpm or more by the rotation drive mechanism 20. Then, the wafer W is heated by the first heater 22 and the second heater .

[0123] 4, at time t0, the supply of the first source gas SG1 into the reaction chamber 10 begins. The first source gas SG1 is introduced from the first source gas supply pipe 81 into the first source gas region 51 and is supplied to the reaction chamber 10 through the first source gas conduit 71. The flow rate of the first source gas SG1 is controlled by the control circuit 12.

[0124] 4, at time t0, the supply of purge gas PG to the reaction chamber 10 begins. The purge gas PG is introduced from the first purge gas supply pipe 83 into the first purge gas region 53, and is then supplied to the reaction chamber 10 through the first purge gas conduit 73. The purge gas PG is also introduced from the second purge gas supply pipe 84 into the second purge gas region 54, and is then supplied to the reaction chamber 10 through the second purge gas conduit 74 and the holes 60b in the rectifier plate 60. The flow rate of the purge gas PG is controlled by the control circuit 12.

[0125] 4, from time t0 to time t1, i.e., during the initial period, for example, the flow rate of the first source gas SG1 is kept constant. Also, during the initial period, for example, the flow rate of the purge gas PG is kept constant.

[0126] As shown in FIG. 5, during the initial period, for example, a first amount of substance (Si SG1 ) and the second amount of substance (Cl SG1 ) is kept constant. Also, as shown in FIG. 5, during the initial period, for example, the third substance amount (Cl PG ) should be constant.

[0127] Furthermore, as shown in FIG. 6, in the initial period, the first amount of substance (SiSG1 ) to the second amount of substance (Cl SG1 ) and the third amount of substance (Cl PG The first source gas SG1 and the purge gas PG are supplied to the reaction chamber 10 so that the ratio ((second amount of substance+third amount of substance) / first amount of substance) of the sum of the second amount of substance and the third amount of substance is 30 or more. In the initial period, the ratio (second amount of substance+third amount of substance) / first amount of substance is, for example, constant.

[0128] During the initial period, the second source gas SG2, which is a source gas of carbon (C), is not supplied into the reaction chamber 10, and therefore the SiC film 13 is not formed on the surface of the wafer W.

[0129] 4, at time t1, the supply of the second source gas SG2 into the reaction chamber 10 begins. The second source gas SG2 is introduced from the second source gas supply pipe 82 into the second source gas region 52 and is supplied to the reaction chamber 10 through the second source gas conduit 72. The flow rate of the second source gas SG2 is controlled by the control circuit 12.

[0130] The first source gas SG1, the second source gas SG2, and the purge gas PG supplied from the gas inlet 11 to the reaction chamber 10 form gas flows toward the surface of the wafer W. Silicon atoms contained in the first source gas SG1 and carbon atoms contained in the second source gas SG2 react with each other on the surface of the wafer W, thereby forming a single-crystal SiC film 13 on the surface of the wafer W.

[0131] 4, the flow rates of the first source gas SG1 and the second source gas SG2 are increased during the flow rate increasing period after the initial period, while the flow rate of the purge gas PG is kept constant during the initial period and the flow rate increasing period.

[0132] As shown in FIG. 5, during the flow rate increase period, the first substance amount (Si SG1 ) and the second amount of substance (Cl SG1 ) increases. Also, as shown in FIG. 5, for example, during the initial period and the flow rate increase period, the amount of the third substance (ClPG ) is kept constant.

[0133] During the initial period and the flow rate increase period, for example, a first amount of substance (Si SG1 ) to the second amount of substance (Cl SG1 ) ratio (amount of second substance / amount of first substance) is kept constant.

[0134] As shown in FIG. 4, during the constant flow rate period following the increased flow rate period, the flow rates of the first source gas SG1, the second source gas SG2, and the purge gas PG are kept constant.

[0135] During the flow rate increasing period and the flow rate constant period, for example, the first substance amount (Si SG1 ) to the fourth amount of substance (C SG2 ) ratio (fourth amount of substance / first amount of substance) is 0.1 or more and 1.2 or less.

[0136] After the SiC film 13 is formed, the heating by the first heater 22 and the second heater 42 is stopped to lower the temperature of the wafer W. Thereafter, the wafer W is carried out from the reaction chamber 10 together with the susceptor 14.

[0137] Next, the operation and effects of the vapor phase growth apparatus and vapor phase growth method of the first embodiment will be described.

[0138] When a SiC film is formed on the surface of a wafer using a vapor phase growth apparatus, defects such as pits and bumps may occur on the surface of the SiC film. The presence of defects on the surface of the SiC film can be problematic, for example, because they can degrade the characteristics of semiconductor devices formed on the SiC film.

[0139] In the vapor phase growth apparatus 100 of the first embodiment, when a SiC film is formed on the surface of a wafer, the control circuit 12 controls the supply of a first source gas containing silicon and chlorine and a purge gas containing chlorine and hydrogen to the reaction chamber 10. The control circuit 12 controls, for example, the flow rate of the first source gas and the flow rate of the purge gas.

[0140] During the initial period of forming a SiC film on the surface of the wafer, the control circuit 12 controls the ratio ((second amount of substance + third amount of substance) / first amount of substance) of the sum of the second amount of substance, which is the amount of chlorine contained in the first source gas SG1 supplied to the reaction chamber 10 per unit time, and the third amount of substance, which is the amount of chlorine contained in the purge gas PG supplied to the reaction chamber 10 per unit time, to the first amount of substance, which is the amount of silicon contained in the first source gas SG1 supplied to the reaction chamber 10 per unit time, to be 30 or more.

[0141] The control circuit 12 further controls the flow rate of the first source gas SG1 so that the flow rate of the first source gas SG1 increases during the flow rate increasing period after the initial period.

[0142] According to the vapor phase growth apparatus 100 of the first embodiment, the above-described configuration makes it possible to suppress the occurrence of defects such as pits and bumps on the surface of the SiC film when the SiC film is formed on the surface of the wafer.

[0143] Furthermore, in the vapor phase growth method of the first embodiment, during an initial period when forming a SiC film on the surface of a wafer, a first source gas SG1 containing silicon and chlorine and a purge gas PG containing chlorine and hydrogen are supplied into reaction chamber 10 so that the ratio ((second amount of substance+third amount of substance) / first amount of substance) of the sum of a second amount of substance which is the amount of substance of chlorine contained in first source gas SG1 supplied per unit time to a first amount of substance which is the amount of substance of silicon contained in first source gas SG1 supplied per unit time to reaction chamber 10 is 30 or greater. Furthermore, during a flow rate increase period after the initial period, the flow rate of first source gas SG1 supplied into reaction chamber 10 is increased.

[0144] According to the vapor phase growth method of the first embodiment, the above configuration makes it possible to suppress the occurrence of defects such as pits and bumps on the surface of the SiC film when the SiC film is formed on the surface of the wafer.

[0145] 7(a) and 7(b) are explanatory diagrams of the operation and effect of the first embodiment. Figures 7(a) and 7(b) are confocal differential interference contrast microscope photographs of the surface of a SiC film. Figure 7(a) shows a SiC film manufactured by a comparative vapor phase growth method, and Figure 7(b) shows a SiC film manufactured by the vapor phase growth method of the embodiment.

[0146] In the comparative vapor phase growth method, (the second amount of substance + the third amount of substance) / the first amount of substance in the initial period, that is, (Cl SG1 +Cl PG ) / Si SG1 In the comparative example, the ratio of the fourth amount of substance to the first amount of substance (fourth amount of substance / first amount of substance) during the flow rate increasing period and the flow rate constant period, i.e., C SG2 / Si SG1 is 0.95.

[0147] On the other hand, in the vapor phase growth method of the embodiment, (the second amount of substance + the third amount of substance) / the first amount of substance, that is, (Cl SG1 +Cl PG ) / Si SG1 In the vapor phase growth method of the embodiment, the ratio of the fourth amount of substance to the first amount of substance (fourth amount of substance / first amount of substance) during the flow rate increasing period and the flow rate constant period, i.e., C SG2 / Si SG1 is 0.95. In the vapor phase growth method of the embodiment, the second amount of substance, which is the amount of chlorine contained in the first source gas SG1, is increased to about 1.8 times that of the example, thereby increasing (second amount of substance+third amount of substance) / first amount of substance in the initial period.

[0148] As shown in Figure 7(a), defects such as pits or bumps are observed on the surface of the SiC film in the comparative example, whereas as shown in Figure 7(b), defects such as pits or bumps are suppressed on the surface of the SiC film in the embodiment.

[0149] Fig. 8 is an explanatory diagram of the action and effect of the vapor phase growth apparatus and vapor phase growth method of the first embodiment. Fig. 8 is a diagram showing the relationship between the number of defects on the surface of the SiC film and the ratio of the sum of the second amount of substance and the third amount of substance to the first amount of substance in the initial period ((second amount of substance + third amount of substance) / first amount of substance). Fig. 8 shows the number of defects on the surface of the SiC film when only the ratio of the sum of the second amount of substance and the third amount of substance to the first amount of substance ((second amount of substance + third amount of substance) / first amount of substance) is changed in a vapor phase growth method similar to the vapor phase growth method of the first embodiment.

[0150] As shown in Figure 8, (the second amount of substance + the third amount of substance) / the first amount of substance, i.e., (Cl SG1 +Cl PG ) / Si SG1 The number of defects on the surface of the SiC film is reduced when the ratio is 30 or more. (second amount of substance+third amount of substance) / first amount of substance is, for example, 200 or less.

[0151] It is believed that by increasing the ratio of chlorine to silicon supplied to the reaction chamber 10 in the early stage of forming the SiC film, the generation of particles containing silicon in the reaction chamber 10 can be suppressed.

[0152] From the viewpoint of reducing the number of defects on the surface of the SiC film, (second amount of substance+third amount of substance) / first amount of substance is preferably 35 or more, and more preferably 40 or more.

[0153] From the viewpoint of stably forming a SiC film, it is preferable to start supplying the second source gas SG2 containing carbon into the reaction chamber 10 after the initial period.

[0154] From the viewpoint of stably forming a SiC film, the first amount of substance (Si SG1 ) to the second amount of substance (Cl SG1 It is preferable that the ratio (amount of second substance / amount of first substance) is constant.

[0155] From the viewpoint of stably forming a SiC film, the amount of the third substance (Cl PG ) is preferably constant.

[0156] The first amount of substance (Si SG1 ) to the fourth amount of substance (C SG2 ) ratio (amount of fourth substance / amount of first substance), i.e., C SG2 / Si SG1 is adjusted to obtain the desired properties of the SiC film to be formed. SG2 / Si SG1 By adjusting the temperature, it is possible to adjust the uniformity of the carrier concentration in the SiC film and the film formation rate.

[0157] From the viewpoint of stably forming a SiC film, the fourth substance amount (C SG2 ) is the C during film formation SG2 / Si SG1 It is preferable that the amount of substance is fixed at a predetermined amount regardless of the amount of substance.

[0158] The fourth amount of carbon contained in the second source gas SG2 (C SG2 ) to C SG2 / Si SG1 If the amount of substance is fixed at a predetermined value regardless of C SG2 / Si SG1 When the film formation conditions are selected so that the first amount of substance (Si SG1 ) becomes larger. The first amount of substance (Si SG1 ) increases, (second amount of substance + third amount of substance) / first amount of substance decreases. Therefore, it is desirable to adjust (second amount of substance + third amount of substance) / first amount of substance to be 30 or more by increasing at least one of the second amount of substance or the third amount of substance.

[0159] For example, the fourth amount of substance / the first amount of substance, i.e., C SG2 / Si SG1If the amount of the second substance (Cl) is less than 1.2, the amount of the third substance (Cl) is increased to make the ratio (the second amount of substance + the third amount of substance) / the first amount of substance 30 or more. SG1 ) or the third amount of substance (Cl PG ) is preferably increased.

[0160] 9, 10, and 11 are explanatory diagrams of the vapor phase growth apparatus and vapor phase growth method of the first embodiment. For example, in order to make the ratio (amount of second substance + amount of third substance) / amount of first substance in the initial state 30 or more, as shown in FIG. 9, the amount of second substance (Cl SG1 ) may be increased. Also, for example, in order to make the ratio (second amount of substance + third amount of substance) / first amount of substance in the initial state 30 or more, as shown in FIG. 10, the third amount of substance (Cl PG ) may be increased. Also, for example, in order to make the ratio (second amount of substance + third amount of substance) / first amount of substance in the initial state 30 or more, as shown in FIG. 11, SG1 ) and the third amount of substance (Cl PG ) may be increased.

[0161] As described above, according to the first embodiment, it is possible to realize a vapor phase growth apparatus and a vapor phase growth method that can reduce defects in a film.

[0162] (Second embodiment) The vapor phase growth apparatus of the second embodiment differs from the vapor phase growth apparatus of the first embodiment in that it includes a mixed source gas flow path that supplies a mixed source gas containing silicon, carbon, and chlorine into the reaction chamber. The vapor phase growth method of the second embodiment also differs from the vapor phase growth method of the first embodiment in that a mixed source gas containing silicon, carbon, and chlorine is supplied into the reaction chamber. Hereinafter, some of the content overlapping with the first embodiment may be omitted.

[0163] 12 is a schematic cross-sectional view of a vapor phase growth apparatus according to a second embodiment. The vapor phase growth apparatus 200 according to the second embodiment is, for example, a single-wafer epitaxial growth apparatus for epitaxially growing a single-crystal SiC film on a single-crystal SiC substrate. The vapor phase growth apparatus 200 according to the second embodiment is a vertical vapor phase growth apparatus in which a process gas is supplied vertically to the surface of the SiC substrate.

[0164] The vapor phase growth apparatus 200 of the second embodiment includes a reaction chamber 10, a gas inlet unit 11, and a control circuit 12 (control unit). The reaction chamber 10 includes a susceptor 14 (holder), a rotor 16, a rotation shaft 18, a rotation drive mechanism 20, a first heater 22, a reflector 28, support columns 30, a fixed base 32, a fixed shaft 34, a hood 40, a second heater 42, and a gas outlet 44. The gas inlet unit 11 includes a mixed source gas region 55, a rectifying plate 60, a top plate 64, and a purge gas conduit 75. The rectifying plate 60 includes gas holes 60x.

[0165] The vapor phase growth apparatus 200 of the second embodiment includes a mixed source gas supply pipe 86, a purge gas supply pipe 87, a first mass flow controller MFC1, a second mass flow controller MFC2, a first valve V1, and a second valve V2.

[0166] The mixed source gas supply pipe 86, the mixed source gas region 55, and the gas holes 60x form a source gas flow path that supplies the mixed source gas SGx to the reaction chamber 10.

[0167] The purge gas supply pipe 87 and the purge gas conduit 75 form a purge gas flow path that supplies the purge gas PG to the reaction chamber 10.

[0168] The first valve V1 and the first mass flow controller MFC1 are provided in the mixed source gas supply pipe 86. The first valve V1 has a function of switching between starting and stopping the introduction of the mixed source gas SGx introduced into the mixed source gas supply pipe 86. The first mass flow controller MFC1 has a function of adjusting the flow rate of the mixed source gas SGx introduced into the mixed source gas supply pipe 86 to a predetermined amount.

[0169] The second valve V2 and the second mass flow controller MFC2 are provided in the purge gas supply pipe 87. The second valve V2 has a function of switching between starting and stopping the introduction of the purge gas PG introduced into the purge gas supply pipe 87. The second mass flow controller MFC2 has a function of adjusting the flow rate of the purge gas PG introduced into the purge gas supply pipe 87 to a predetermined amount.

[0170] The first valve V1, the second valve V2, the first mass flow controller MFC1, and the second mass flow controller MFC2 are controlled by a control circuit 12.

[0171] The gas inlet 11 is provided above the reaction chamber 10 .

[0172] The mixed source gas SGx is introduced into the mixed source gas region 55 from a mixed source gas supply pipe 86. The mixed source gas region 55 is provided between the rectifying plate 60 and the top plate 64.

[0173] The rectifying plate 60 is provided between the reaction chamber 10 and the mixed source gas region 55. The rectifying plate 60 has a plurality of gas holes 60x.

[0174] A top plate 64 is provided above the source gas mixture region 55 .

[0175] The mixed source gas SGx is a source gas of silicon (Si) and carbon (C). The mixed source gas SGx includes silicon (Si), carbon (C), and chlorine (Cl). The mixed source gas SGx includes, for example, silane (SiH4) or chlorosilane (SiH4-nCln: n=1 to 4). The mixed source gas SGx includes, for example, hydrocarbon. The mixed source gas SGx includes, for example, hydrogen chloride (HCl). The mixed source gas SGx includes, for example, hydrogen gas (H2). The mixed source gas SGx is, for example, a mixed gas of silane (SiH4), propane (C3H8), hydrogen chloride (HCl), and hydrogen gas (H2).

[0176] The mixed source gas SGx includes, for example, an n-type impurity dopant gas, such as nitrogen gas.

[0177] The purge gas PG has a function of adjusting the distribution of the mixed source gas SGx supplied into the reaction chamber 10 on the wafer W, for example.

[0178] The purge gas PG contains chlorine (Cl) and hydrogen (H). The purge gas PG contains, for example, hydrogen chloride (HCl). The purge gas PG contains, for example, hydrogen gas (H2). The purge gas PG is, for example, a mixed gas of hydrogen chloride (HCl) and hydrogen gas (H2). Instead of hydrogen gas (H2), for example, argon gas (Ar) can be used.

[0179] The atomic concentration of chlorine in the purge gas PG is lower than that in the source gas mixture SGx, for example, the atomic concentration of chlorine in the purge gas PG is, for example, one-fifth or less of the atomic concentration of chlorine in the source gas mixture SGx.

[0180] The control circuit 12 controls the first valve V1, the second valve V2, the first mass flow controller MFC1, and the second mass flow controller MFC2. The control circuit 12 is an example of a control unit.

[0181] The control circuit 12 controls, for example, the opening and closing of the first valve V1 and the second valve V2. The control circuit 12 sends, for example, command values for gas flow rates to the first mass flow controller MFC1 and the second mass flow controller MFC2.

[0182] The control circuit 12 controls the flow rate of the mixed source gas SGx by, for example, sending a command value for the flow rate of the mixed source gas SGx to the first mass flow controller MFC1. The control circuit 12 controls the flow rate of the purge gas PG by, for example, sending a command value to the second mass flow controller MFC2.

[0183] 13 is an explanatory diagram of control by the control circuit of the vapor phase growth apparatus of the second embodiment. Fig. 13 is a diagram showing the change over time in the flow rate of the process gas supplied to the reaction chamber 10 of the vapor phase growth apparatus 200. The flow rate of the process gas is controlled by the control circuit 12.

[0184] When forming a SiC film on the wafer W, the control circuit 12 controls so that at time t0, the supply of the mixed source gas SGx and the purge gas PG to the reaction chamber 10 is started. Specifically, for example, the control circuit 12 sends a command signal to the first valve V1 and the second valve V2 at time t0 to open the first valve V1 and the second valve V2 and start the supply of the mixed source gas SGx and the purge gas PG to the reaction chamber 10.

[0185] The control circuit 12 controls the flow rates of the mixed source gas SGx and the purge gas PG to be desired flow rates. Specifically, for example, the control circuit 12 adjusts the openings of the first mass flow controller MFC1 and the second mass flow controller MFC2 by sending command signals to the first mass flow controller MFC1 and the second mass flow controller MFC2, thereby controlling the flow rates of the mixed source gas SGx and the purge gas PG to be desired flow rates.

[0186] The control circuit 12 controls the flow rates of the mixed source gas SGx and the purge gas so that they are constant, for example, from time t0 to time t1. The period from time t0 to time t1 is referred to as an initial period. The initial period is an example of a first period.

[0187] The control circuit 12 controls the flow rate of the mixed source gas SGx to increase, for example, from time t1 to time t2. The control circuit 12 also controls the flow rate of the purge gas PG to be constant, for example, from time t1 to time t2. The period from time t1 to time t2 is referred to as a flow rate increase period. The flow rate increase period is an example of a second period.

[0188] The flow increase period is a period following the initial period, and the flow increase period and the initial period are consecutive.

[0189] After time t2, the control circuit 12 controls the flow rates of the mixed source gas SGx and the purge gas so that they are constant. The period after time t2 is referred to as a constant flow rate period.

[0190] The constant flow rate period is the period following the increased flow rate period. The constant flow rate period and the increased flow rate period are continuous.

[0191] 14 is an explanatory diagram of control by the control circuit of the vapor phase growth apparatus of the second embodiment. Fig. 14 is a diagram showing the time change in the amount of silicon (Si) and the amount of chlorine (Cl) per unit time in the process gas supplied to the reaction chamber 10 of the vapor phase growth apparatus 200. The amount of silicon (Si) and the amount of chlorine (Cl) per unit time are controlled by the control circuit 12.

[0192] In the initial period, the control circuit 12 controls the first amount of silicon (Si SGx ), the second amount of chlorine (Cl SGx ), the third amount of substance (Cl PG ) is controlled to be constant.

[0193] If the atomic concentration of silicon contained in the mixed source gas SGx and the atomic concentration of chlorine contained in the mixed source gas SGx are constant, and the flow rate of the mixed source gas SGx is kept constant in the initial period as shown in FIG. 13, the first amount of substance (Si SGx ) and the second amount of substance (Cl SGx ) is constant. In this case, the first amount of substance (Si SGx ) to the second amount of substance (Cl SGx ) ratio (amount of second substance / amount of first substance) remains constant.

[0194] For example, if the atomic concentration of chlorine contained in the purge gas PG is constant, and the flow rate of the purge gas PG is kept constant in the initial period as shown in FIG. 13, the third amount of substance (Cl PG ) becomes constant.

[0195] During the flow rate increasing period, the control circuit 12 controls the flow rate of the first substance (Si SGx ) and the second amount of substance (Cl SGx ) is increased. In addition, the control circuit 12 controls the amount of the third substance (Cl PG ) is controlled to be constant.

[0196] If the atomic concentration of silicon contained in the mixed source gas SGx and the atomic concentration of chlorine contained in the mixed source gas SGx are constant, then if the flow rate of the mixed source gas SGx is increased as shown in FIG. 13 during the flow rate increase period, the first substance amount (Si SGx ) and the second amount of substance (Cl SGx In this case, the first amount of substance (Si SGx ) to the second amount of substance (Cl SGx ) ratio (amount of second substance / amount of first substance) is kept constant.

[0197] For example, if the atomic concentration of chlorine contained in the purge gas PG is constant, and the flow rate of the purge gas PG is kept constant during the flow rate increase period as shown in FIG. 13, the third amount of substance (Cl PG ) becomes constant.

[0198] The control circuit 12 controls the flow rate of, for example, a first substance amount (Si SGx ), the second amount of substance (Cl SGx ), and the third amount of substance (Cl PG ) is controlled to be constant.

[0199] If the atomic concentration of silicon contained in the mixed source gas SGx and the atomic concentration of chlorine contained in the mixed source gas SGx are constant, and the flow rate of the mixed source gas SGx is kept constant as shown in FIG. 13, the first amount of substance (Si SGx ) and the second amount of substance (Cl SGx ) is constant. In this case, the first amount of substance (Si SGx ) to the second amount of substance (Cl SGx ) ratio (amount of second substance / amount of first substance) is kept constant.

[0200] For example, if the atomic concentration of chlorine contained in the purge gas PG is constant, and the flow rate of the purge gas PG is kept constant as shown in FIG. 13, the third amount of substance (Cl PG ) becomes constant.

[0201] 15 is an explanatory diagram of control by the control circuit of the vapor phase growth apparatus of the second embodiment. FIG. 15 shows the first amount of substance (Si SGx ) to the second amount of substance (Cl SGx ) and the third amount of substance (Cl PG 1 shows the time change in the ratio ((second amount of substance+third amount of substance) / first amount of substance) of the sum of the second amount of substance and the third amount of substance. ((second amount of substance+third amount of substance) / first amount of substance) is controlled by control circuit 12.

[0202] In the initial period, the control circuit 12 controls the first amount of substance (Si SGx ) to the second amount of substance (Cl SGx ) and the third amount of substance (Cl PG The ratio of the sum of the second amount of substance and the third amount of substance ((second amount of substance + third amount of substance) / first amount of substance) is controlled to be 30 or more. (Second amount of substance + third amount of substance) / first amount of substance is (Cl SGx +Cl PG ) / Si SGx It can be written as:

[0203] The control circuit 12 controls the flow rate of the mixed source gas SGx and the flow rate of the purge gas PG in consideration of the atomic concentration of silicon and the atomic concentration of chlorine contained in the mixed source gas SGx and the atomic concentration of chlorine contained in the purge gas PG, thereby making it possible to set (second amount of substance+third amount of substance) / first amount of substance to 30 or more. (second amount of substance+third amount of substance) / first amount of substance is, for example, 30 or more and 200 or less.

[0204] The control circuit 12 controls the flow rates of the mixed source gas SGx and the purge gas PG as shown in Fig. 13, thereby keeping (second amount of substance + third amount of substance) / first amount of substance constant during the initial period. Also, by controlling the flow rates of the mixed source gas SGx and the purge gas PG as shown in Fig. 13, the (second amount of substance + third amount of substance) / first amount of substance decreases during the flow rate increasing period. Also, by controlling the flow rates of the first source gas SG1 and the purge gas PG as shown in Fig. 13, the (second amount of substance + third amount of substance) / first amount of substance constant during the flow rate constant period.

[0205] The control circuit 12 controls, for example, a fourth amount of substance (C SG2 The control circuit 12 controls the flow rates of the silicon source gas and the carbon source gas before mixing, for example, using a mass flow controller (not shown).

[0206] Next, a vapor phase growth method according to a second embodiment will be described.

[0207] The vapor phase growth method of the second embodiment uses a vapor phase growth apparatus 200 shown in Fig. 12. An example will be described in which a single crystal SiC film 13 (silicon carbide film) is formed on the surface of a wafer W of single crystal SiC.

[0208] The source gas mixture SGx contains silicon, carbon, and chlorine, and the purge gas PG contains chlorine and hydrogen.

[0209] The following description will be given taking as an example a case where the mixed source gas SGx is a mixed gas of silane (SiH4), propane (C3H8), hydrogen chloride (HCl), and hydrogen gas (H2), and the purge gas PG is a mixed gas of hydrogen chloride (HCl) and hydrogen gas (H2).

[0210] The atomic concentration of silicon in the mixed source gas SGx, the atomic concentration of carbon in the mixed source gas SGx, the atomic concentration of chlorine in the mixed source gas SGx, and the atomic concentration of chlorine in the purge gas PG are each kept constant.

[0211] First, the susceptor 14 on which the wafer W is placed is carried into the reaction chamber 10. The wafer W is made of single crystal SiC.

[0212] Next, the wafer W is rotated at a rotation speed of 300 rpm or more by the rotation drive mechanism 20. Then, the wafer W is heated by the first heater 22 and the second heater .

[0213] 13, at time t0, the supply of the mixed source gas SGx into the reaction chamber 10 is started. The mixed source gas SGx is introduced from the mixed source gas supply pipe 86 into the mixed source gas region 55, and is supplied to the reaction chamber 10 through the gas holes 60x of the rectifying plate 60. The flow rate of the mixed source gas SGx is controlled by the control circuit 12.

[0214] 13, at time t0, the supply of purge gas PG to the reaction chamber 10 begins. The purge gas PG is supplied from the purge gas supply pipe 87 through the purge gas conduit 75 to the reaction chamber 10. The flow rate of the purge gas PG is controlled by the control circuit 12.

[0215] 13, from time t0 to time t1, i.e., during the initial period, for example, the flow rate of the mixed source gas SGx is kept constant. Also, during the initial period, for example, the flow rate of the purge gas PG is kept constant.

[0216] As shown in FIG. 14, during the initial period, for example, a first amount of substance (SiSGx ) and the second amount of substance (Cl SGx ) is kept constant. Also, as shown in FIG. 14, during the initial period, for example, the third amount of substance (Cl PG ) should be constant.

[0217] Furthermore, as shown in FIG. 15, in the initial period, the first substance amount (Si SGx ) to the second amount of substance (Cl SGx ) and the third amount of substance (Cl PG The mixed source gas SGx and the purge gas PG are supplied to the reaction chamber 10 so that the ratio ((second amount of substance+third amount of substance) / first amount of substance) of the sum of the second amount of substance and the third amount of substance is 30 or more. In the initial period, the ratio (second amount of substance+third amount of substance) / first amount of substance is, for example, constant.

[0218] The mixed source gas SGx and the purge gas PG supplied from the gas inlet 11 to the reaction chamber 10 form a gas flow toward the surface of the wafer W. Silicon atoms and carbon atoms contained in the mixed source gas SGx react with each other on the surface of the wafer W, thereby forming a single-crystal SiC film 13 on the surface of the wafer W.

[0219] 13, the flow rate of the mixed source gas SGx is increased in a flow rate increasing period after the initial period. Note that, as shown in FIG. 13, in the initial period and the flow rate increasing period, for example, the flow rate of the purge gas PG is kept constant.

[0220] As shown in FIG. 14, during the flow rate increase period, the first substance amount (Si SGx ) and the second amount of substance (Cl SGx ) increases. Also, as shown in FIG. 14, for example, in the initial period and the flow rate increasing period, the amount of the third substance (Cl PG ) is kept constant.

[0221] During the initial period and the flow rate increase period, for example, a first amount of substance (Si SGx ) to the second amount of substance (Cl SGx ) ratio (amount of second substance / amount of first substance) is kept constant.

[0222] As shown in FIG. 13, in the constant flow rate period following the increased flow rate period, the flow rate of the mixed source gas SGx and the flow rate of the purge gas PG are kept constant.

[0223] During the flow rate increasing period and the flow rate constant period, for example, the first substance amount (Si SGx The ratio of the fourth amount of substance to the first amount of substance (fourth amount of substance / first amount of substance) is 0.1 or more and 1.2 or less.

[0224] After the SiC film 13 is formed, the heating by the first heater 22 and the second heater 42 is stopped to lower the temperature of the wafer W. Thereafter, the wafer W is carried out from the reaction chamber 10 together with the susceptor 14.

[0225] According to the vapor phase growth apparatus and vapor phase growth method of the second embodiment, in an initial period, the ratio ((second amount of substance+third amount of substance) / first amount of substance) of the sum of the second amount of substance, which is the amount of substance of chlorine contained in the mixed source gas SGx supplied per unit time to the reaction chamber 10, and the third amount of substance, which is the amount of substance of chlorine contained in the purge gas PG supplied per unit time to the first amount of substance, which is the amount of substance of silicon contained in the mixed source gas SGx supplied per unit time to the reaction chamber 10, is controlled to be 30 or more. Therefore, as in the first embodiment, when a SiC film is formed on the surface of a wafer, defects such as pits and bumps are suppressed from occurring on the surface of the SiC film.

[0226] As described above, according to the second embodiment, it is possible to realize a vapor phase growth apparatus and a vapor phase growth method that can reduce defects in the film.

[0227] The embodiments of the present invention have been described above with reference to specific examples. The above-described embodiments are merely examples and do not limit the present invention. Furthermore, the components of each embodiment may be combined as appropriate.

[0228] In the first and second embodiments, the case of forming a single crystal SiC film has been described as an example, but the present invention can also be applied to the formation of a polycrystalline or amorphous SiC film.

[0229] Furthermore, in the first and second embodiments, a single crystal SiC wafer has been described as an example of the substrate, but the substrate is not limited to a single crystal SiC wafer.

[0230] In the first and second embodiments, nitrogen is used as an n-type impurity, but it is also possible to use, for example, phosphorus (P) as the n-type impurity. It is also possible to use a p-type impurity as the impurity.

[0231] Furthermore, in the first and second embodiments, a single-wafer epitaxial growth apparatus that forms a film on a single wafer has been described as an example, but the present invention can also be applied to a batch-type epitaxial growth apparatus that forms films on multiple wafers simultaneously.

[0232] In addition, in the first embodiment, the atomic concentration of silicon in the first source gas SG1, the atomic concentration of chlorine in the first source gas SG1, the atomic concentration of carbon in the second source gas SG2, and the atomic concentration of chlorine in the purge gas PG are constant. However, it is also possible to change the atomic concentration of silicon in the first source gas SG1, the atomic concentration of chlorine in the first source gas SG1, the atomic concentration of carbon in the second source gas SG2, or the atomic concentration of chlorine in the purge gas PG.

[0233] Furthermore, in the second embodiment, the case has been described where the atomic concentration of silicon in the mixed source gas SGx, the atomic concentration of carbon in the mixed source gas SGx, the atomic concentration of chlorine in the mixed source gas SGx, and the atomic concentration of chlorine in the purge gas PG are constant, but it is also possible to change the atomic concentration of silicon in the mixed source gas SGx, the atomic concentration of carbon in the mixed source gas SGx, the atomic concentration of chlorine in the mixed source gas SGx, or the atomic concentration of chlorine in the purge gas PG.

[0234] Furthermore, in the first embodiment, an example has been described in which the second source gas SG2 is not supplied to the reaction chamber 10 during the initial period, but it is also possible to supply the second source gas SG2 to the reaction chamber 10 during the initial period.

[0235] Furthermore, in the second embodiment, the carbon source gas is supplied to the reaction chamber 10 in the initial period. However, it is also possible not to supply the carbon source gas to the reaction chamber 10 in the initial period.

[0236] In the first and second embodiments, descriptions of the apparatus configuration, manufacturing method, and other aspects not directly necessary for explaining the present invention have been omitted, but the required apparatus configuration, manufacturing method, and the like can be appropriately selected and used. In addition, all vapor phase growth apparatuses that incorporate the elements of the present invention and whose design can be appropriately modified by those skilled in the art are encompassed within the scope of the present invention. The scope of the present invention is defined by the claims and their equivalents. [Explanation of symbols]

[0237] 10 Reaction chamber 11 Gas inlet 12 Control circuit (control section) 13 SiC film (silicon carbide film) 14 Susceptor (holder) 100 Vapor phase growth equipment 200 Vapor phase growth equipment SG1 First source gas SG2 Second Source Gas SGx source gas mixture PG Purge Gas W wafer (substrate)

Claims

1. A reaction chamber; a holder provided in the reaction chamber and configured to place a substrate thereon; a source gas flow path for supplying a first source gas containing silicon and chlorine into the reaction chamber; a purge gas flow path that supplies a purge gas containing chlorine and hydrogen into the reaction chamber; a control unit that controls the supply of the first source gas and the purge gas into the reaction chamber; the control unit controls a ratio ((second amount of substance+third amount of substance) / first amount of substance) of a sum of a second amount of substance, which is an amount of substance of chlorine contained in the first source gas supplied to the reaction chamber per unit time, and a third amount of substance, which is an amount of substance of chlorine contained in the purge gas supplied to the reaction chamber per unit time, to a first amount of substance, which is an amount of substance of silicon contained in the first source gas supplied to the reaction chamber per unit time, during a first period, to be 30 or more; The control unit controls the flow rate of the first source gas to increase during a second period after the first period.

2. the controller further controls supply of a second source gas comprising carbon into the reaction chamber; 2. The vapor deposition apparatus according to claim 1, wherein the control unit controls to start supplying the second source gas into the reaction chamber after the first period.

3. 3. The vapor phase growth apparatus according to claim 2, wherein the control unit controls a ratio of a fourth amount of substance, which is an amount of substance of carbon contained in the second source gas supplied to the reaction chamber per unit time, to the first amount of substance (fourth amount of substance / first amount of substance) to be 1.2 or less.

4. 3. The vapor phase growth apparatus according to claim 1, wherein the control unit controls the ratio of the second amount of substance to the first amount of substance (second amount of substance / first amount of substance) to be constant during the first period and the second period.

5. 3. The vapor phase growth apparatus according to claim 1, wherein the control unit controls the amount of the third substance to be constant during the first period and the second period.

6. 1. A vapor phase growth method for forming a silicon carbide film on a substrate placed on a holder provided in a reaction chamber, comprising: supplying a first source gas containing silicon and chlorine and a purge gas containing chlorine and hydrogen into the reaction chamber during a first period of time such that a ratio ((second amount of substance+third amount of substance) / first amount of substance) of the sum of a second amount of substance, which is the amount of substance of chlorine contained in the first source gas supplied to the reaction chamber per unit time, and a third amount of substance, which is the amount of substance of chlorine in the purge gas supplied to the reaction chamber per unit time, to a first amount of substance, which is the amount of substance of silicon contained in the first source gas supplied to the reaction chamber per unit time, is 30 or more; a second period of time after the first period of time, the flow rate of the first source gas supplied into the reaction chamber being increased;

7. 7. The method of claim 6, further comprising the step of: starting to supply a second source gas containing carbon into said reaction chamber after said first period of time.

8. 8. The vapor phase growth method according to claim 7, wherein a ratio of a fourth amount of substance, which is an amount of carbon contained in the second source gas supplied to the reaction chamber per unit time, to the first amount of substance (fourth amount of substance / first amount of substance) is 1.2 or less.

9. 8. The vapor phase growth method according to claim 6, wherein a ratio of the second amount of substance to the first amount of substance (second amount of substance / first amount of substance) is constant during the first period and the second period.

10. 8. The vapor phase growth method according to claim 6, wherein the amount of the third substance is constant during the first period and the second period.

Images