JP4601701B2 - Vapor phase growth apparatus and gas supply method - Google Patents

Description

  The present invention relates to a vapor phase growth apparatus and a gas supply method.

  As a method for producing a group III-V compound semiconductor thin film used for a light emitting diode, a semiconductor laser, a compound solar cell, etc., an organometallic material containing a group III element such as trimethylgallium, trimethylaluminum, trimethylindium, ammonia, phosphine There is a vapor phase growth method in which a thin film is formed by a chemical reaction with a hydrogen compound gas containing a group V element such as arsine. In the vapor phase growth method, a thin film is formed by supplying the gas into a reaction furnace and causing a chemical reaction on a heated substrate.

  There is a MOCVD apparatus (Metal Organic Chemical Vapor Deposition) as a vapor deposition apparatus using this method. The thin film obtained by the MOCVD apparatus is excellent in in-plane uniformity of film thickness and film quality, and is also superior in mass productivity as compared with a molecular beam epitaxial growth apparatus (MBE apparatus) for crystal growth of a compound semiconductor. Therefore, it is an apparatus generally used in the industry for manufacturing compound semiconductors.

  The MOCVD apparatus generally has (1) a gas supply system that supplies an organic metal material, a hydride gas, a carrier gas, and a purge gas under flow control, and (2) the gas supply system is connected and a substrate is installed inside And a reaction furnace having a mechanism capable of heating and rotating the substrate and having an exhaust system for discharging the supplied gas, and (3) a detoxification system for detoxifying the gas discharged from the reaction furnace and exhausting it to the outside Consists of The present invention relates to the internal structure of the reactor (2) above among the above three elements constituting the MOCVD apparatus. Hereinafter, the structure in the reaction furnace of the conventional MOCVD apparatus will be described. The organometallic material and hydride gas supplied on the substrate are hereinafter referred to as source gas. A gas supplied onto the substrate including the source gas and the carrier gas is referred to as a process gas.

  FIG. 11 shows a cross-sectional view of the reactor portion of the MOCVD apparatus according to the prior art. This MOCVD apparatus is called a horizontal flow type, and employs a gas supply method in which a gas used for film formation flows from one direction in parallel to the substrate surface.

  The supplied process gas forms a laminar flow. Therefore, the source gas diffuses on the substrate through the boundary layer formed between the substrate 105 and the reaction proceeds on the substrate 105 provided in the susceptor 106. Accordingly, in the reaction furnace, the process gas is rectified in one direction (lateral direction) from the upstream side to the downstream side, and a flow path including the substrate 105 is formed so as not to disturb the gas flow as much as possible. In the figure, the reaction furnace is generally provided with a metal chamber 101 such as stainless steel, and a gas supply port 102 is provided at one end and a gas exhaust port 103 is provided at the other end.

  The gas supply port 102 is a part for supplying a process gas, and the gas exhaust port 103 is a port for discharging an unreacted gas, an intermediate product generated by a chemical reaction, or surplus gas such as a carrier gas. Connected to a system (not shown).

  The reaction furnace 120 is provided with a reaction tube (flow path) 104 positioned inside the gas supply port 102 and the gas exhaust port 103. The reaction tube 104 is made of quartz or the like. Various gases supplied from the direction of the gas supply port 102 pass through the reaction tube 104 and are exhausted in the direction of the gas exhaust port 103. Therefore, the supplied various gases are rectified into a one-way flow through the reaction tube 104 and guided to the surface of the substrate 105.

  The reaction tube 104 is also called a flow channel, and is a structural member generally used in a lateral flow type MOCVD apparatus. The shape of the reaction tube 104 is generally a rectangular parallelepiped shape (box shape) or a cylindrical shape, and is integrally formed from the gas supply port 102 to the installation portion of the substrate 105 and the gas exhaust port 103. Alternatively, the flow path is formed by fitting each part of the reaction tube 104 formed partially. In addition, on the upstream side of the flow, a partition 104a may be provided so that different source gases are not mixed and reacted so quickly.

  Next, the peripheral structure of the substrate 105 and the susceptor 106 will be described with reference to FIG. FIG. 12 is a cross-sectional view showing the internal structure of the reaction furnace portion of the conventional MOCVD apparatus shown in FIG. A substrate 105 and a susceptor 106 on which the substrate 105 is placed are installed at a substantially central portion of the reaction tube 104 to form a part of the flow path. A heater 107 for heating the substrate 105 is installed below the susceptor 106.

  The substrate 105 is placed on the susceptor 106. The surface of the susceptor 106 is provided with a dent corresponding to the shape of the substrate 105. The depth of the digging is the surface of the susceptor 106 so as not to disturb the gas flow ( The setting is made so that the surface of the substrate 105 and the surface of the substrate 105 are substantially the same. Further, the surface of the susceptor 106 is installed so as to be substantially flush with the reaction tube bottom plate 104 b of the reaction tube 104.

  A heater 107 for heating the substrate is installed below the susceptor 106. The heater 107 has a disk shape. Further, the susceptor 106 is supported by a susceptor support bar 111 installed in the vicinity of the center portion on the back surface (opposite side of the substrate installation surface) of the susceptor 106. An opening is formed in the central portion of the heater 7, and the susceptor support bar 111 passes through the opening of the heater 107.

  The thermocouple 112 is introduced through the susceptor support rod 111 having a hollow structure. Based on the temperature measured by the thermocouple 112, the temperature of the heater 107 is controlled. In general, the temperature is controlled to be a temperature set in advance in the thermocouple 112.

  The susceptor support rod 111 is connected to a rotation mechanism (not shown), and rotates the susceptor 106 in order to improve the temperature uniformity of the substrate 105. Note that the heater 107 and the thermocouple 112 are non-rotating and do not contact the susceptor 106. Further, on the side surface and the lower side of the heater 107, a side reflector 109 is provided to suppress heat from the heater 107 from being radiated to the side surface and the lower side, to increase heating efficiency and to prevent a temperature rise in the peripheral portion. And the bottom reflector 110 is installed.

  With the above structure, power consumption can be suppressed and heat can be efficiently conducted to the substrate 105 side. Further, the influence of heat on the peripheral part such as the chamber wall surface is reduced, heat resistance measures are not required, and the apparatus cost can be reduced. Note that the side reflector 109 and the bottom reflector 110 may be formed as an integral type or divided, and in either case, a space close to a hermetic space is around the heater 107 in order to suppress heat dissipation as much as possible. Will be formed.

  Furthermore, in order to enhance the effect of the side reflector 109 or the bottom reflector 110, a plurality of reflectors may be installed. However, in the case of adopting a structure in which the heat dissipation to the periphery of the heater 107 is suppressed as much as possible and the hermeticity is improved by the above configuration, it takes a very long time for cooling when the substrate is taken out after film formation. This leads to a tact-down in the operation of the apparatus, and in the case of a mass production apparatus, productivity is impaired.

  Next, regarding the gas flow during film formation, what kind of gas flow is generated in the vicinity of the heater 107 will be described. Most of the process gas flowing in one direction from the upstream direction (gas supply port 102 side) of the reaction tube 104 passes over the substrate 105 and flows to the downstream gas exhaust port 103 side.

  However, a part of the gas A flows downward from the gap between the susceptor 106 and the reaction tube bottom plate 104 b and reaches the periphery of the heater 107. The gas A once flowing in is discharged from the apparatus exhaust system by being discharged to the outside through a gap between the side reflector 109 and the bottom reflector 110 or an exhaust port (not shown) that is intentionally installed.

  When the gas A that flows in here contains a raw material gas and the reactivity of the gas is high, it reacts with the heater 107 that is at a high temperature, and in some cases corrodes the heater 107 and changes the heat generation characteristics. In the worst case, the heater breaks. When the heater characteristics become unstable, the influence on the film formation is large, and the reproducibility of the film characteristics deteriorates. In the case of heater replacement, it takes a long time to start up, such as replacement work, degassing processing of a new heater, and re-measuring the relationship between heater supply power and substrate temperature.

  In order to prevent the above-described problem that cooling takes time or causes deterioration of the heater, purge gas is supplied in the vicinity of the heater. As the purge gas, a gas that does not affect the film formation is used. For example, hydrogen gas used as a carrier gas for the source gas, or an inert gas such as nitrogen gas or argon gas is used. As the purge gas supply flow path, the hollow space of the susceptor support rod is often used. In this case, the purge gas is allowed to flow in the vicinity of the heater 107 from the lower side of the heater 107, thereby shortening the cooling time and isolating or diluting the reaction gas around the heater. During cooling, the heater 107 and the central portion of the susceptor 106 may be locally cooled, and a uniform effect cannot be expected with respect to corrosion resistance. Similarly, since the thermocouple supplied from the hollow of the susceptor support rod is also locally cooled, the deviation from the actual temperature is not constant, and the temperature adjustment becomes difficult.

  FIG. 13 is a cross-sectional view showing a conventional vertical MOCVD apparatus (shower head type MOCVD apparatus). In FIG. 13, the same members as those described in FIG. The vertical MOCVD apparatus shown in FIG. 13 is provided with a shower plate 115 and is greatly different from the horizontal MOCVD apparatus shown in FIG. 11 in that a reaction gas and a carrier gas are supplied from the shower plate 115. In addition, a gas supply source 122 serving as a supply source of the reaction gas and the carrier gas, and an exhaust gas treatment device 123 connected to the gas exhaust port 103 for detoxifying the gas exhausted through the purge line 103a are also provided. Yes.

  Also in such a shower type MOCVD apparatus, the diffusion of the source gas around the heater 107 occurs, and the heater deteriorates due to corrosion.

  FIG. 14 is a cross-sectional perspective view showing a conventional MOCVD apparatus (central emission type MOCVD apparatus). 14, the same members as those described in FIG. 12 are denoted by the same member numbers, and the description thereof is omitted. The central radiation type MOCVD apparatus places a plurality of substrates on the circumference of a susceptor and supplies process gas radially from the vicinity of the center of the susceptor. Therefore, on the substrate, a process gas flow is formed horizontally on the substrate surface, and a chemical reaction similar to that of the lateral flow type MOCVD apparatus occurs. Even in such a central radiation type MOCVD apparatus, diffusion of the raw material gas around the heater occurs, and the heater deteriorates due to corrosion.

  For example, Patent Document 1 discloses a horizontal MOCVD apparatus including a dedicated pipe 114 in order to deal with such a problem that the heater is deteriorated. FIG. 15 is a cross-sectional view showing a horizontal MOCVD apparatus disclosed in Patent Document 1. As shown in FIG. As shown in FIG. 15, it is disclosed that in a horizontal MOCVD apparatus, a dedicated pipe 114 is provided so that purge gas can be actively supplied to the vicinity of the heater, and cooling is efficiently performed. As for the control of the temperature control system, a purge gas is shut off when the temperature is raised, and a system that supplies the purge gas at the same time as the heater is turned off is assembled to improve the tact time.

Further, Patent Document 2 discloses a plasma CVD apparatus provided with a reflector 108. FIG. 16 is a cross-sectional view showing a plasma CVD apparatus disclosed in Patent Document 2. A reflector 108 is provided immediately below the lower electrode 107a of the plasma CVD apparatus. FIG. 17 is a perspective view of the reflector 108. As shown in the figure, the reflector 108 has a hollow structure, and a dispersion hole is provided on the upper surface of the reflector 108. In Patent Document 2, it is proposed to improve the cooling efficiency of electrodes and reflectors by the cooling gas supplied into the hollow of the reflector 108.
JP 2000-114180 A (published on April 21, 2000) JP-A-8-69969 (published March 12, 1996)

  However, the conventional vapor phase growth apparatus described above has a problem that a local concentration distribution of the purge gas in the vicinity of the heater is likely to occur.

  More specifically, in the horizontal MOCVD apparatus of FIG. 15, the heater 107 is irradiated with the purge gas via the dedicated pipe 114, so that the cooling time is shortened, while the purge gas ejection portion is located with respect to the heater position. It is installed unevenly. For this reason, the amount of purge gas contacted differs depending on the part of the heater, and the temperature distribution is generated in the heater 107 itself, so that distortion due to the thermal stress difference occurs, and in some cases, the heater 107 may be destroyed or broken.

  In consideration of corrosion resistance, it is necessary to always flow purge gas during film formation. However, uneven supply of purge gas (supply with uneven concentration) affects the heat generation distribution of the heater, resulting in adverse effects on the substrate temperature distribution. Will cause the crystal quality to deteriorate.

  Further, with respect to the heater corrosion resistance, when the purge gas is applied with an uneven weight as in the disclosed technology and discharged from one place like the discharge port 109a, the flow is disturbed in the vicinity of the heater as shown in the enlarged view in the figure. In some cases, the process gas that has flowed in may stay in the vicinity of the heater and cause local corrosion of the heater. Further, when the size of the discharge port 109a is increased in order to reduce the turbulence of the flow, the heat from the heater 107 is radiated from the discharge port 109a, so that the side reflector does not function as a reflector. In order to further suppress gas stagnation, when the purge gas flow rate is increased and the purge gas flow rate in the vicinity of the heater 107 is increased, the purge gas flows back into the reaction tube, and the reaction gas flow (laminar flow) is disturbed. It will adversely affect the film formation.

  From the above viewpoint, the disclosed technique of Patent Document 1 is effective in shortening the cooling time, but the biased purge gas irradiation (the concentration is biased) affects the substrate temperature distribution, leading to deterioration of crystal quality. . In addition, the effect of extending the life of the heater is poor, and conversely, local cooling leads to a shortened life of the heater. If the life of the heater is shortened, the replacement work of the heater becomes frequent, and the operation rate of the apparatus is lowered, so that productivity is impaired.

  Moreover, since the cooling method of the plasma CVD apparatus disclosed in Patent Document 2 has a structure in which gas is supplied from the reflector to the entire heater surface, it can be used for the heater purge of the MOCVD apparatus. On the other hand, since the substrate temperature is lower in the plasma CVD apparatus than in the MOCVD apparatus, a partition wall such as a side reflector is unnecessary. However, when applied to an MOCVD apparatus that performs crystal growth at a high temperature, a side reflector is indispensable. In that case, due to variations in the gas flow velocity from the dispersion holes, the heater periphery is also filled with gas, and the flow is It is conceivable that there is a turbulent and locally gas retaining portion.

  Therefore, although a certain effect can be expected for cooling after the end of the process, if a highly reactive gas flows in during the process as in the case of the MOCVD apparatus, the purge gas stays around the heater that is at a high temperature. Due to the diffusion to the part, corrosion proceeds, causing the life of the heater to be shortened.

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a vapor phase growth apparatus capable of uniformly supplying a purge gas to a heater. Furthermore, the present invention provides a vapor phase growth apparatus that solves the above-mentioned problems related to the MOCVD apparatus and can maintain a stable yield for a long period of time efficiently while increasing the operation rate of the apparatus without impairing the film formation quality. For the purpose.

  In order to solve the above problems, the vapor phase growth apparatus of the present invention has a heater for heating a substrate to be subjected to vapor phase growth, a susceptor for holding the substrate, and an opposite side of the substrate to the heater. In a vapor phase growth apparatus comprising a plate-like and a plurality of facing reflectors installed horizontally to suppress heat dissipation on the facing side of the heater, and a side reflector that suppresses heat dissipation on the side surface of the heater, First purge gas supply means for supplying purge gas to the plurality of facing reflectors from the opposite side of the substrate with respect to the heater, and purge gas discharge means for discharging the purge gas, each of the plurality of facing reflectors includes a plurality of Ventilation holes are formed, and among the plurality of facing reflectors, a plurality of ventilation holes formed in adjacent facing reflectors are opposed to each other. It is characterized in that it is formed in the absence position.

  According to the above configuration, the purge gas can be supplied to the facing reflector by the first purge gas supply means. Since a plurality of ventilation holes are formed in the facing reflector, the supplied purge gas passes through the plurality of ventilation holes formed in the facing reflector and collides with an adjacent facing reflector. As a result, the gas flow rate distribution of the purge gas is made uniform, and finally the purge gas can be supplied uniformly to the heater, that is, in the form of a shower.

  In the vapor phase growth apparatus of the present invention, it is preferable that the purge gas discharge means is provided in the vicinity of the side surface of the heater.

  For this reason, since the purge gas is discharged from the purge gas discharge means in the vicinity of the heater side surface, it is possible to suppress the purge gas supplied from the first purge gas supply means from staying in the vicinity of the heater. Therefore, it is possible to provide a vapor phase growth apparatus that can supply the purge gas more uniformly to the heater.

  In the vapor phase growth apparatus of the present invention, a second purge gas supply means for supplying a purge gas is provided on the opposite side of the substrate from the heater, and the second purge gas supply means is perpendicular to the susceptor. Further, it is preferably arranged on a vertical axis located at the center of the susceptor, and a purge gas is preferably supplied around itself.

  Thereby, in addition to the supply from the first purge gas supply means, the purge gas can also be supplied from the second purge gas supply means, and the variation of supplying the purge gas can be increased.

  In the vapor phase growth apparatus of the present invention, it is preferable that the susceptor and the heater are disposed via a space, and the second purge gas supply means supplies a purge gas to the space between the susceptor and the heater. .

  Thereby, in addition to the first purge gas supply means, the second purge gas supply means can supply the purge gas to the space between the susceptor and the heater, so that the flow of the purge gas can be further stabilized. For this reason, as compared with the case where the purge gas is supplied only from the first purge gas supply means, it is possible to further reduce the deviation of the concentration distribution of the purge gas in the vicinity of the heater.

  In the vapor phase growth apparatus of the present invention, the flow rate Q2 of the purge gas supplied from the second purge gas supply unit and the flow rate Q1 of the purge gas supplied from the first purge gas supply unit satisfy Q2 ≦ Q1 and It is preferable to satisfy the relationship of Q2 / Q1 ≦ 100.

  As a result, it is possible to further avoid the possibility that the purge gas is likely to stay, and to further prevent the concentration distribution of the purge gas from being biased in the vicinity of the heater.

  In order to solve the above problems, the vapor phase growth method of the present invention includes a heater for heating a substrate to be subjected to vapor phase growth, a susceptor for holding the substrate, and an opposite side of the substrate to the heater. Purge gas is supplied to a vapor phase growth apparatus comprising a plate-like and plural facing reflectors installed horizontally to suppress heat dissipation on the facing side of the heater and a side reflector that suppresses heat dissipation on the side surface of the heater. In the gas supply method to be supplied, the vapor phase growth apparatus includes: a first purge gas supply unit that supplies a purge gas to the plurality of facing reflectors from a side opposite to the susceptor with respect to the heater; and a purge gas discharge that discharges the purge gas. And a plurality of air holes are formed in each of the plurality of facing reflectors, and the plurality of facing reflections are provided. The plurality of vent holes formed in the adjacent facing reflectors of the filter are formed at positions that do not face each other, and purge gas is supplied from the first purge gas supply means to the plurality of facing reflectors. It is said.

  According to the above configuration, the purge gas can be supplied to the facing reflector by the first purge gas supply means. Since a plurality of ventilation holes are formed in the facing reflector, the supplied purge gas passes through the plurality of ventilation holes formed in the facing reflector and collides with an adjacent facing reflector. As a result, the gas flow rate distribution of the purge gas is made uniform, and finally the purge gas can be supplied uniformly to the heater, that is, in the form of a shower.

  As described above, the vapor phase growth apparatus of the present invention suppresses heat dissipation on the plate-like and plurality of facing reflectors installed horizontally to suppress heat dissipation on the facing side of the heater, and on the side surface side of the heater. In the vapor phase growth apparatus including the side reflector, the first purge gas supply means for supplying the purge gas to the plurality of facing reflectors from the opposite side of the substrate with respect to the heater, and the purge gas discharge means for discharging the purge gas are provided. Each of the plurality of facing reflectors is formed with a plurality of ventilation holes, and among the plurality of facing reflectors, the plurality of ventilation holes formed in the adjacent facing reflectors are formed at positions that do not face each other. It is what.

  Therefore, the purge gas can be supplied to the facing reflector by the first purge gas supply means. Since a plurality of ventilation holes are formed in the facing reflector, the supplied purge gas passes through the plurality of ventilation holes formed in the facing reflector and collides with an adjacent facing reflector. As a result, the gas flow velocity distribution of the purge gas is made uniform, and finally the purge gas can be supplied uniformly to the heater, that is, in a shower form.

  In addition, since a flow with few gas staying parts can be formed, heater damage due to the inflowing reaction gas is reduced, and since there is no uneven supply, heater heat generation distribution does not occur and the uniformity of the substrate temperature distribution is impaired. The film characteristics can be made uniform and the heater can have a long service life.

[Embodiment 1]
An embodiment of the present invention will be described with reference to FIGS. 1 to 9 as follows. FIG. 1 shows a cross-sectional view of a reactor of an MOCVD apparatus (vapor phase growth apparatus) according to this embodiment. The basic structure in the reaction furnace is the same as the structure in the reaction furnace of the conventional MOCVD apparatus shown in FIG. That is, a gas supply port 2 that supplies a process gas into the chamber 1, a reaction tube 4 that leads the gas to the substrate 105 and then forms a flow path to the gas exhaust port 3, and a gas exhaust system (not shown) ) Is connected to the gas exhaust port 3.

  A susceptor 6 on which the substrate 5 is placed is disposed at a substantially central portion of the reaction tube 4, and a heater 7 for heating the substrate 5 is disposed at the lower portion of the susceptor 6. A power supply line 14 is connected to the heater 7. Furthermore, a susceptor support rod (second purge gas supply means) 11 that supports the susceptor supports the susceptor 6 at the center of the susceptor 6. An opening is formed in the center of the heater 7, and the susceptor support rod 11 has a structure that passes through the opening of the heater 7. A thermocouple 12 is disposed in the susceptor support rod 11.

  In addition, although a substrate rotation mechanism and a susceptor lifting mechanism are attached, they are not shown because they become complicated. The above member is the basic configuration.

  The substrate 5 is a member which is subjected to vapor phase growth and becomes a place where a crystal film grows. The substrate 5 is not particularly limited as long as vapor deposition can be performed, and a known substrate used for vapor deposition can be used. In addition, for convenience of explanation, in FIG. 1, the substrate 5 is configured to be installed at one place, but is not limited to the number of installations, and a configuration in which the substrate 5 is installed at a plurality of places may be used.

  The susceptor 6 holds the substrate 5. Similar to the substrate 5, a known susceptor used in a vapor phase growth apparatus can be used. When the substrate 5 is installed at a plurality of locations, the susceptor 6 is also installed at a plurality of locations corresponding to the substrate 5. In some cases, an integrated susceptor on which a plurality of substrates are installed is used. The shape of the susceptor is not limited to the shape shown in FIG. 1, and there may be a shape in which an opening is provided in a part of the substrate installation surface and the radiant heat is directly irradiated from the heater. . Although the disk-shaped thing is employ | adopted as the heater 7, as long as the board | substrate 5 can be heated, it is not limited to a disk shape. The heater 7 is disposed via the susceptor 6 and a space. Configurations other than the basic configuration will be described with reference to FIG.

  Next, the peripheral part of the heater 7 in the reaction furnace of FIG. 1 will be described in more detail with reference to FIG. FIG. 2 is a cross-sectional view showing the vicinity of the heater 7 in the reaction furnace of the MOCVD apparatus of FIG.

  As a structure around the heater in FIG. 2, in addition to the above basic configuration, facing reflectors 8 a, 8 b, and 8 c are provided on the opposite side of the substrate 5 with respect to the heater 7. A side reflector 9 is provided on the side surface of the heater 7 so as to accommodate the heater 7 and the facing reflectors 8 a, 8 b, and 8 c, and a rear reflector 10 is provided so as to connect the side reflector 9. Further, a purge gas supply pipe (first purge gas supply means) 13 is inserted from the rear reflector 10.

  The facing reflectors 8 a, 8 b and 8 c are installed horizontally on the opposite side of the substrate 5 with respect to the heater 7 in order to suppress heat radiation on the facing side of the heater 7. As shown in the figure, a plate-like and a plurality of facing reflectors are provided. Further, the facing reflectors 8 a, 8 b, and 8 c are disposed closer to the heater 7 than the rear reflector 10, and are members for suppressing heat from the heater from being radiated to the opposite side of the substrate 5. . As the material of the front reflector, a high melting point metal such as molybdenum, tantalum, or tungsten, or a ceramic material such as alumina or boron nitride can be used. The face-to-face reflector will be described in detail later.

  The side reflector 9 and the rear reflector 10 cover the heater 7 and suppress heat dissipation around the heater 7. The side reflector 9 and the rear reflector 10 are in contact with each other without any gap. However, contact is not essential. Further, in FIG. 2, the side reflector 9 is provided with a single layer in a cylindrical shape, but is not limited to this shape, and may be provided with two or more layers, that is, double tubes or more. Thereby, the heat radiation around the heater 7 can be further suppressed. A set of members existing in a region substantially surrounded by the side reflector, the rear reflector, and the heater may be collectively referred to as a heater unit.

  The purge gas supply pipe 13 is a member that supplies purge gas to the heater 7. The heater 7 can be cooled by supplying the purge gas. The purge gas supply pipe 13 is provided so as to pass through the rear reflector 10, and the tip of the purge gas supply pipe 13 is not in contact with the front reflector 8 c and is arranged with a gap. As the purge gas, a gas that does not contribute to the reaction, such as hydrogen gas, nitrogen gas, or argon gas, may be used.

  The arrangement of the purge gas supply pipe 13 is not particularly limited as long as it has a pipe opening at a position below the facing reflector 8c. However, if it is in the immediate vicinity of the facing reflector 8c, the purge gas may be insufficiently diffused between the facing reflector 8c and the facing reflector 8b. It is desirable.

  Further, the three facing reflectors 8a, 8b, and 8c will be described with reference to FIG. 3 in order to explain more clearly. FIG. 3 is a perspective view showing the front reflectors 8a, 8b, and 8c. As shown in the figure, the facing reflectors 8a, 8b, 8b are arranged horizontally with a space therebetween. In this embodiment, the interval is set at 1 mm, but the interval is not limited to this.

  Each of the facing reflectors 8a, 8b, and 8c arranged in parallel has vent holes formed at 16 locations, and a plurality of vent holes formed between adjacent front reflectors are formed at positions that do not face each other. Yes. In other words, the plurality of vent holes formed in the facing reflectors 8a, 8b, and 8c arranged in parallel are formed at positions that do not coincide with each other between adjacent facing reflectors along a direction perpendicular to the facing reflector. It can also be said that it is formed at a position that does not overlap along a direction perpendicular to the facing reflector.

  In the present embodiment, the vents arranged on the reflectors 8a, 8b, 8c are arranged in a straight line in the radial direction of the reflector. However, the present invention is not limited to this. You may arrange | position on the periphery which has a different radius. However, in that case, it is required to arrange the vents so that the circumferential radii are different between the adjacent reflectors. Further, the vents may be arranged in a staggered pattern in the facing reflector. Even in this case, it is required that the positions of the vent holes do not coincide in the vertical direction in the reflectors adjacent to each other.

  In addition, although the said vent hole is formed circularly, if it is formed in said position, the shape will not be specifically limited.

  Further, in the reaction furnace of FIG. 2, three facing reflectors are provided. However, if at least two facing reflectors are provided, the vapor phase growth apparatus of the present invention can be configured.

  Since the vent holes formed in the facing reflectors 8a, 8b, and 8c are arranged as described above, as shown in FIG. 2, when the purge gas is supplied from the purge gas supply pipe 13, the vent holes of the front reflector 8c are provided. The purge gas that has passed through collides with the front reflector 8b. Thereafter, the purge gas is dispersed along the front reflector 8b, and further passes through the ventilation holes of the facing reflector 8b. A similar process is performed for the facing reflector 8 a, and purge gas is supplied to the vicinity of the heater 7. For this reason, the purge gas cannot reach the vicinity of the heater 7 without colliding with the facing reflector.

  As described above, the purge gas supplied from the purge gas supply pipe 13 passes through the plurality of vent holes provided in the facing reflectors 8a, 8b, 8c, and the purge gases collide with each other between the facing reflectors. Since the purge gas is guided to the heater 7 while repeating this, the purge gas flow direction is randomly dispersed, and at the same time, the gas flow velocity distribution reaches the heater 7 while becoming uniform. Finally, the purge gas is uniformly irradiated in a shower-like shape upward from a plurality of vent holes installed in the uppermost facing reflector 8a immediately before reaching the heater 7.

  Further, in the vicinity of the side surface of the heater 7, a clearance is provided between the upper surface side (susceptor side) of the side reflector 9 and the reaction tube bottom plate 4 b forming the flow path. ) 9a is formed. That is, since the supplied purge gas is discharged using the gap as an exhaust port, a constant flow rate is ensured in the flow of the purge gas, and the irradiated purge gas can be prevented from staying in the vicinity of the heater 7. For this reason, according to the vapor phase growth apparatus concerning this embodiment, the deviation of concentration distribution near heater 7 can be controlled, and purge gas can be supplied to a heater more uniformly.

  Here, the vicinity of the side surface of the heater 7 specifically refers to the susceptor 6 from a position facing the heater 7 in the side reflector 9 that houses (encloses) the heater 7 and the facing reflectors 8a, 8b, and 8c. It means the position up to the position. In FIG. 2, the discharge port 9 a is formed on the surface of the side reflector 9 that faces the susceptor 6.

  Furthermore, in the vapor phase growth apparatus shown in FIG. 2, as a preferred embodiment, the susceptor support rod 11 has a hollow structure, and purge gas is supplied from below the susceptor support rod 11 to the susceptor side. An opening is formed at the tip of the susceptor support rod 11 that contacts the susceptor 6, and purge gas is supplied from the opening to the space between the susceptor 6 and the heater 7. Thereafter, the purge gas is discharged from the discharge port 9a.

  Since the vapor phase growth apparatus has a configuration in which the purge gas is supplied from the susceptor support rod 11, the flow of the purge gas is further stabilized by combining with the flow of the purge gas supplied in a shower form from the facing reflectors 8a, 8b, and 8c. be able to. For this reason, as compared with the case where the purge gas is supplied only from the purge gas supply pipe 13, it is possible to further reduce the deviation of the concentration distribution of the purge gas in the vicinity of the heater 7.

  More specifically, when the purge gas flow from the purge gas supply pipe 13 is the first purge gas and the purge gas flowing through the susceptor support rod 11 is the second purge gas, the second purge gas is added to the first purge gas flow. A radial flow can be formed from the vicinity of the central portion of the heater 7 to the peripheral portion.

  At this time, by optimizing the balance of the flow rates of the first and second purge gases, the flow to the discharge port 9a can be further stabilized, and the gas retention portion can be further reduced. The flow rate balance is preferably such that the flow rate Q2 of the second purge gas does not exceed the flow rate Q1 of the first purge gas, and the flow rate Q2 satisfies the relationship of Q2 ≦ Q1 and Q2 / Q1 ≦ 100 with respect to the flow rate Q1. Is preferred. When the above relationship is satisfied, a stay portion is less likely to occur in the supplied purge gas.

  With the above-described configuration, the purge gas is uniformly diffused and supplied in the vicinity of the heater 7 and a gas flow with a constant flow rate is formed, so that the purge gas flow acts as a barrier gas during film formation, and the heater 7 It becomes difficult for the reactive gas to flow into the side. Further, even if a corrosive process gas flows in between the reaction tube bottom plate 4 b and the susceptor 6, it does not stay near the heater 7 and is discharged from the discharge port 9 a. For this reason, reaction with the heater 7 is reduced, and the lifetime of the heater 7 can be significantly improved.

  Further, since the heater 7 is uniformly irradiated with the purge gas, the heat generated by the heater 7 is uniformly stabilized in the surface, and the temperature distribution uniformity of the substrate 5 can be improved. This leads to an improvement in crystal quality and can improve the yield. Even if the purge gas flow path cannot be formed on the central axis of the susceptor 6 due to physical interference, the purge gas can be supplied from the position of the purge gas supply pipe 13 shifted from the central axis. The degree of freedom can also be increased.

  Note that although the horizontal flow type MOCVD apparatus is described in this embodiment mode, the present invention can also be applied to a vertical MOCVD apparatus that supplies a reaction gas from above the substrate in FIG. 14 is also applicable to a central radiation type MOCVD apparatus in which a plurality of substrates 5 are mounted on the circumference of the susceptor 6 and gas is supplied radially from the center of the susceptor 6.

  Next, in order to clarify the effect of the present invention, the result of evaluating the flow of purge gas around the heater by thermal fluid analysis will be shown. The thermal fluid analysis to be used is a method for obtaining a state relating to the gas flow in the modeled vapor phase growth apparatus by numerical analysis using a computer, which is widely used in general. The analysis results regarding the models of six types of vapor phase growth apparatuses including the vapor phase growth apparatus shown in FIG. 2 are shown in FIGS. A small arrow in the figure is a flow vector. In addition, the analysis result in which the quasi-three-dimensional calculation in which one section is rotated with the susceptor support rod 11 as the central axis C is shown for each model.

  About the size of each model, it is the same dimension about common parts, such as the supply piping diameter of purge gas, and the clearance gap of the discharge port 9a, and the reference | standard is based on the vapor phase growth apparatus of FIG. 2 which concerns on this Embodiment. Therefore, the same reference numerals as those in FIG. The purge gas supply flow rate is also the same. Even when purge gas is supplied from the two systems of the purge gas supply pipe 13 and the susceptor support rod 11, the same flow rate is supplied from each system, so that twice as much purge gas is supplied as in the case of only one system. become. Further, a side reflector 9 exists as a boundary condition below the discharge port 9a, but is not described in the calculation model.

  FIG. 4 is a diagram showing an analysis result of a model of the vapor phase growth apparatus according to the present invention, and shows a model in which purge gas is supplied only from the purge gas supply pipe 13 in the vapor phase growth apparatus in FIG. That is, the susceptor support rod 11 is not formed with an opening for supplying purge gas. As shown in the figure, the facing reflectors 8a, 8b, 8c are provided with a plurality of vent holes. The purge gas is supplied from the purge gas supply pipe 13 and is discharged from the discharge port 9a.

  From this analysis result, although the purge gas flow is disturbed immediately after the purge gas is supplied from the purge gas supply pipe 13, the gas flow is reduced by the structure in which the facing reflectors 8 a, 8 b, 8 c have a plurality of vent holes. It can be seen that the heater 7 is diffused and uniformly irradiated. Further, it can be seen that there is no large gas flow disturbance around the heater 7 and the gas is discharged from the discharge port 9a.

  FIG. 5 is a diagram showing the analysis result of the model of the vapor phase growth apparatus according to the present invention, and targets the model corresponding to the vapor phase growth apparatus shown in FIG. That is, the purge gas is supplied from the susceptor support rod 11 radially from the vicinity of the center of the susceptor in the vicinity of the heater. In this case, similarly to the model shown in FIG. 4, the effect of the purge gas diffusion supply by the structure (porous structure) provided with a plurality of ventilation holes of the facing reflectors 8 a, 8 b, 8 c and the central radial shape from the inside of the susceptor support rod 11 This flow of gas further stabilizes the flow of purge gas. Finally, the purge gas is discharged from the discharge port 9a, and the gas retention part is hardly seen.

  This analysis result is obtained when the flow rate Q1 of the first purge gas from the purge gas supply pipe 13 and the flow rate Q2 of the second purge gas from the susceptor support rod 11 are the same, but the flow rate ratio of both Q1 and Q2 is changed. As a result, when Q1> Q2, the flow is similar to that shown in FIG. 4, but the gas flow is not greatly disturbed.

  However, when Q1 <Q2 and the flow ratio Q2 / Q1 exceeds 100, it was confirmed that the gas flow was greatly disturbed and a gas retention part was generated. Therefore, in the case of the purge mechanism of this structure, the flow rate Q2 of the second purge gas from the center and the first purge gas flow rate Q1 supplied in the form of a diffusion shower through the bottom reflector are Q2 ≦ Q1 and Q2 / Q1 It is desirable to satisfy the relationship of ≦ 100.

  FIG. 6 is a diagram showing an analysis result regarding a model of a comparative vapor phase growth apparatus. Unlike the face-to-face reflector 8a according to the present embodiment, the reflector 108 of the model does not have a vent hole. Further, the purge gas supply pipe 113 is installed in the vicinity of the heater 7 and has a configuration similar to that of Patent Document 1 disclosed as the prior art.

  From the analysis result of FIG. 6, it can be seen that immediately after the purge gas is supplied from the purge gas supply pipe 113 to the heater 107, a large gas turbulence occurs, and a gas retention portion exists in the vicinity of the turbulence. When the reaction gas mixed from the gap of the susceptor 106 moves to the vicinity of the heater 107 by diffusion, the reaction gas stays for a long time. The result shown in FIG. 6 can be said to be a result showing that the contact opportunity between the heater 107 held at a high temperature and the reaction gas increases, which may cause corrosion.

  FIG. 7 is a diagram showing an analysis result regarding a model of a comparative vapor phase growth apparatus. Unlike the facing reflector 8a according to the present embodiment, the reflector 108a has a vent hole, but the vent holes formed in the adjacent reflectors 108a are arranged to face each other. For example, a case where a mechanism portion such as a push-up mechanism is mounted on the vent hole is assumed.

  From the analysis results shown in FIG. 7, a large gas turbulence occurs immediately after the purge gas passes through the vent holes provided in each reflector 108a, and a gas retention portion can be seen. Similarly, a gas retention portion can be seen in the vicinity of the heater 107. Therefore, similarly to the analysis result of FIG. 6, the reaction gas stays in the gas retaining portion, and therefore the corrosion of the heater 107 is likely to proceed.

  FIG. 8 is a diagram showing an analysis result regarding a model of a comparative vapor phase growth apparatus. In the model shown in the figure, the susceptor support rod 111 has a hollow structure, purge gas is supplied therein, a purge gas supply port is provided in the vicinity of the heater 107, and purge gas is supplied in the vicinity of the heater 107. Further, since the discharge port 109a is also provided, the purge gas forms a radial flow from the central portion of the susceptor 106 toward the discharge port 109a. However, according to the analysis result, a gas retention portion is generated near the supply port where the purge gas is supplied from the susceptor support rod 111, and no gas flow is formed in the vicinity of the lower portion of the heater 107. I understand that. Therefore, even in this structure, the retention of the reaction gas mixed around the heater 107 occurs, and the corrosion of the heater 107 is likely to proceed.

  FIG. 9 is a diagram showing an analysis result regarding a model of a comparative vapor phase growth apparatus. In the model shown in the figure, the facing reflector 108b has a hollow structure, and a configuration in which a porous structure is provided on the upper surface side of the facing reflector 108b is shown. The configuration is similar to Patent Document 2 disclosed as the prior art. Become. The purge gas supplied from the purge gas supply pipes 113 and 113b is once supplied into the facing reflector 108b having a hollow structure, but the purge gas flow is disturbed in the vicinity of the purge gas supply pipes 113 and 113a.

  A plurality of ventilation holes are provided on the upper surface of the facing reflector 108b. It can be seen that the gas irradiated from the vent hole in the vicinity of the purge gas flow described above is disturbed and stays in the vicinity of the heater 7. Therefore, even in this structure, it is considered that the mixed reactive gas stays and the corrosion of the heater 107 proceeds.

  As described above, according to the present invention, unlike the calculation results shown in FIGS. 6 to 9, the purge gas can be uniformly supplied to the lower surface of the heater. In addition, since the above-mentioned facing reflector that stabilizes the flow of the purge gas is provided, it is possible to reduce the staying portion in the vicinity of the heater and to reduce the inflow of the reaction gas, thereby extending the life of the heater. In addition, by stabilizing the in-plane uniformity of the substrate temperature, the crystal quality can be stabilized and the yield can be improved.

  The description relating to the above-mentioned vapor phase growth apparatus is also made simultaneously with respect to the gas supply method for supplying purge gas from the purge gas supply pipe to the plurality of facing reflectors in the vapor phase growth apparatus. The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, and the technical means disclosed in different embodiments can be appropriately combined. Such embodiments are also included in the technical scope of the present invention.

[Embodiment 2]
The following will describe another embodiment according to the present invention with reference to FIG. Configurations other than those described in the present embodiment are the same as those in the first embodiment. For convenience of explanation, members having the same functions as those shown in the drawings of Embodiment 1 are given the same reference numerals, and descriptions thereof are omitted.

  FIG. 10 is a cross-sectional view showing the periphery of the heater 7 in the reaction furnace of the MOCVD apparatus according to the present embodiment. The vapor phase growth apparatus shown in the figure has the same configuration as the vapor phase growth apparatus shown in FIG. 2 such as the facing reflectors 8a, 8b, and 8c, except that the purge gas supply pipe 13 is not provided, Instead, the purge gas supply port 13b is formed around the susceptor support rod 11 so as to penetrate the rear reflector 10.

  Purge gas is supplied into the reaction furnace from the purge gas supply port 13b. As the purge gas, one that uses a reactor purge gas (not shown) that is supplied into the chamber and used for wall surface contamination and cooling is used. Then, a part of the reactor purge gas flows from the purge gas supply port. The supplied purge gas passes through three facing reflectors 8 a, 8 b, 8 c each having a plurality of holes, and is supplied to the heater 7. The purge gas passes through a plurality of vent holes provided in each facing reflector, and repeatedly collides between the facing reflectors, so that the gas flow velocity distribution is made uniform and finally the heater 7 is uniformly showered. Will be supplied.

  With the above configuration, as in the vapor phase growth apparatus according to the first embodiment, the purge gas is uniformly diffused and supplied in the vicinity of the heater 7 and a gas flow with a constant flow rate is formed. During film formation, the purge gas flow acts as a barrier gas, making it difficult for the reaction gas to flow into the heater 7 side. Further, even if corrosive reaction gas flows in between the reaction tube bottom plate 4 b and the susceptor 6, it does not stay near the heater 7 and is discharged from the discharge port 9 a. For this reason, reaction with the heater 7 is reduced, and the lifetime of the heater 7 can be significantly improved.

  Further, since the heater 7 is uniformly irradiated with the purge gas, the heat generated by the heater 7 is uniformly stabilized in the surface, and the temperature distribution uniformity of the substrate 5 can be improved. This leads to an improvement in crystal quality and can improve the yield. Even if the purge gas flow path cannot be formed on the central axis of the susceptor 6 due to physical interference, the purge gas can be supplied from the position of the purge gas supply pipe 13 shifted from the central axis. The degree of freedom can also be increased.

  Further, it is of course possible to supply the second purge gas from the susceptor support rod 11, and when the second purge gas is supplied, the flow is stably formed radially from the center portion to the peripheral portion of the heater 7. It is possible to further stabilize the flow up to the discharge port 9a and further reduce the gas retention portion.

  The vapor phase growth apparatus that can uniformly supply the purge gas to the heater according to the present invention can be provided, and can be used in various fields using the vapor phase growth apparatus.

It is sectional drawing of the reaction furnace of the MOCVD apparatus (vapor phase growth apparatus) which concerns on this Embodiment. It is sectional drawing which shows the heater 7 periphery in the reaction furnace of the MOCVD apparatus of FIG. It is a perspective view which shows facing reflector 8a, 8b, 8c. It is a figure which shows the analysis result of the model of the vapor phase growth apparatus which concerns on this invention. It is a figure which shows the analysis result of the model of the vapor phase growth apparatus which concerns on this invention. It is a figure which shows the analysis result regarding the model of the vapor phase growth apparatus for a comparison. It is a figure which shows the analysis result regarding the model of the vapor phase growth apparatus for a comparison. It is a figure which shows the analysis result regarding the model of the vapor phase growth apparatus for a comparison. It is a figure which shows the analysis result regarding the model of the vapor phase growth apparatus for a comparison. It is sectional drawing which shows the heater 7 periphery in the reactor of the MOCVD apparatus which concerns on other embodiment of this invention. Sectional drawing of the reactor part of the MOCVD apparatus which concerns on a prior art is shown. It is sectional drawing which shows the internal structure of the reaction furnace part of the conventional MOCVD apparatus shown in FIG. It is sectional drawing which shows the conventional vertical MOCVD apparatus. It is sectional drawing which shows a center radiation | emission type MOCVD apparatus. It is sectional drawing which shows the conventional horizontal type MOCVD apparatus. It is sectional drawing which shows the conventional plasma CVD apparatus. It is a perspective view of the reflector 108 with which the plasma CVD apparatus of FIG. 16 is provided.

Explanation of symbols

3 Discharge port (Purge gas discharge means)
5 Substrate 6 Susceptor 7 Heater 8a-e Face-to-face reflector 9 Side reflector 10 Rear reflector 11 Susceptor support rod (second purge gas supply means)
12 thermocouple 13 purge gas supply pipe (first purge gas supply means)

Claims (5)

A heater for heating a substrate to be subjected to vapor phase growth, a susceptor for holding the substrate, and a heater on the opposite side of the substrate with respect to the heater are installed horizontally to suppress heat radiation on the opposite side of the heater. In a vapor phase growth apparatus comprising a plate-like and a plurality of facing reflectors, and a side reflector that suppresses heat dissipation on the side of the heater,
A first purge gas supply means for supplying purge gas to the plurality of facing reflectors from the opposite side of the substrate with respect to the heater; and a purge gas discharge means for discharging the purge gas;
A plurality of air holes are formed in each of the plurality of facing reflectors,
A vapor phase growth apparatus characterized in that, among the plurality of facing reflectors, a plurality of vent holes formed in adjacent facing reflectors are formed at positions that do not face each other.   2. The vapor phase growth apparatus according to claim 1, wherein the purge gas discharge means is provided in the vicinity of a side surface of the heater. Second purge gas supply means for supplying purge gas is provided on the opposite side of the substrate to the heater,
3. The second purge gas supply means is disposed on a vertical axis that is perpendicular to the susceptor and is positioned at the center of the susceptor, and supplies the purge gas around itself. The vapor phase growth apparatus described in 1. The susceptor and the heater are arranged through a space,
4. The vapor phase growth apparatus according to claim 3, wherein the second purge gas supply means supplies a purge gas to a space between the susceptor and the heater. A heater for heating a substrate to be subjected to vapor phase growth, a susceptor for holding the substrate, and a heater on the opposite side of the substrate with respect to the heater are installed horizontally to suppress heat radiation on the opposite side of the heater. In a gas supply method for supplying a purge gas to a vapor phase growth apparatus comprising a plate-like and a plurality of facing reflectors, and a side reflector that suppresses heat radiation on the side of the heater,
The vapor phase growth apparatus includes a first purge gas supply unit that supplies a purge gas to the plurality of facing reflectors from a side opposite to the susceptor with respect to the heater, and a purge gas discharge unit that discharges the purge gas.
A plurality of air holes are formed in each of the plurality of facing reflectors,
Among the plurality of facing reflectors, a plurality of air holes formed in adjacent facing reflectors are formed at positions that do not face each other,
A gas supply method, wherein purge gas is supplied from the first purge gas supply means to the plurality of facing reflectors.

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