JPH07111244A - Vapor phase crystal growth apparatus - Google Patents

Abstract

PURPOSE:To prevent reaction products from adhering to components such as a heater provided beneath the susceptor of a vapor phase crystal growth apparatus. CONSTITUTION:A cylinder 17 which covers components beneath a susceptor is provided on the bottom part of a reaction furnace 1. Further, a piping 1c which supplies carrier gas from the bottom part of the reaction furnace 1 toward the bottom part of the susceptor 2 is provided. By this constitution, the fluctuation of heat radiation can be suppressed and a crystal growth temperature can be stabilized, so that the layer thickness, carrier concentration and composition of a growth layer can be uniform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor phase crystal growth apparatus for growing a crystal of a compound semiconductor or the like using a vapor phase reaction, and more particularly to a metal organic vapor phase growth apparatus (MOCVD: Metal Org
anic ChemicalVapor Deposition).

[0002]

2. Description of the Related Art FIG. 11 shows a conventional high speed rotary MOCVD.
It is a sectional view of a reaction furnace part of the apparatus, in which 1 is SU
A cylindrical reactor made of S, 2 is a disk-shaped susceptor installed in the reactor 1, 3 is a wafer tray detachably mounted on the susceptor 2, and 4 is housed in a groove of the wafer tray 3. Further, for example, a semiconductor substrate such as a GaAs substrate, 5 is a circular heater for heating the susceptor 2 from below, 6 is a circular heat shield plate disposed below the heater 5,
Reference numeral 7 is an electrode of the heater, 8 is a rotary shaft which is fixed to the susceptor 2 and rotates the susceptor 2, 9 is a thermocouple for detecting the temperature of the heater 5, and 12 and 13 are introduced into the reactor 1. First and second meshes for uniformly mixing the gas to be charged, 10 are openings for transferring the wafer tray 3 into the reaction furnace 1, and 20a and 20b and 20c are the reaction furnace 1.
A carrier gas supply pipe and a material gas supply pipe for supplying a carrier gas and a material gas, respectively. Reference numeral 11 is a needle valve attached to each of the pipes 20a, 20b, 20c for distributing the flow rate of each gas. Further, a rotary pump 16 is provided downstream of the exhaust port 1a of the reaction furnace 1, and a suction pressure of gas in the reaction furnace 1 is set by a pressure adjusting valve 15 in the preceding stage. Further, 14 is a filter provided in the preceding stage of the pressure control valve, which removes dust and the like from the gas in the reaction furnace 1 and sends the gas to the pressure control valve 15.

A feature of the high-speed rotation type vapor phase growth apparatus is that the material gas is supplied while rotating the susceptor on which the wafer is mounted at a high speed, and the supplied material gas is swirled around the center of the susceptor to gather. However, this material gas flows from the center of the susceptor so as to spread evenly around the susceptor center, which has the advantage of increasing the uniformity of growth between the wafers.

Next, the operation during crystal growth will be described.
A wafer tray 3 on which a semiconductor substrate (here, a GaAs substrate) 4 is mounted at a predetermined location is loaded into the reaction furnace from the opening 10 of the reaction furnace 1, and the wafer tray 3 is attached to the susceptor 2 in the reaction furnace 1. Install on top of. Next, the reactor 1
Hydrogen gas (H2), which is a carrier gas, is introduced from the upper carrier gas supply pipe 20a, and the inside of the reaction furnace 1 is set to a desired set pressure, for example, 50 Torr. At this time, the carrier gas (H2) is uniformly spread by the first mesh 12 and supplied into the reaction furnace 1.

Next, the susceptor 2 is gradually rotated until it reaches a desired number of revolutions, for example, 1000 rpm. Next, the heater 5 is heated, and arsine (AsH3) which is a group V material gas is added to the reactor 1 through the material gas supply pipe 20b in order to suppress the thermal decomposition of the substrate 4 (mainly the loss of As atoms).
It is introduced into and heated to a set temperature, for example 700 °.
At this time, the heat generated by the heater 5 is reflected by the two heat shield plates 6 arranged below, and most of the heat is directed to the susceptor 2 side. The temperature at this time is monitored by the thermocouple 9 in the reaction furnace 1. Since AsH3 has a higher decomposition temperature than TMG described later, it is necessary to supply a relatively large amount to maintain the concentration on the substrate 4.

Next, from the material gas supply pipe 20c to the reactor 1
A material gas such as TMG is introduced from above to grow crystals for a desired time. Here, AsH3 and TMG are uniformly spread by the second mesh 13 provided in the upper part of the reaction furnace 1 and reach the GaAs substrate 4. As a result, the film thickness of the GaAs crystal grown on the GaAs substrate 4,
Uniformity such as carrier concentration can be improved.

Next, the introduction of the gas such as TMG is stopped,
The heating of the heater 5 is stopped while flowing AsH3 so that As in the grown crystal does not escape. When the temperature has dropped to the desired temperature, the introduction of AsH3 is stopped, and then the rotational speed of the susceptor 2 is gradually decreased to stop it.
Then, the wafer tray 3 is taken out from the opening 10 of the reaction furnace 1, and the GaAs substrate 4 on which the crystal has grown is taken out. In addition,
When growing AlGaAs, material gas supply pipe 2
From 0c, TMA (trimethylaluminum) is supplied together with TMG.

[0008]

Since the conventional vapor phase crystal growth apparatus is constructed as described above, in order to exhaust gas from the lower side of the reaction furnace, the reaction gas flows into the low temperature area below the susceptor. As shown in FIG. 12, the reaction product 17 resulting from the thermal decomposition of the supplied reaction gas adheres to the tube wall of the reaction furnace 1, the heat shield plate 6 and the rotary shaft 8. Therefore, the heat radiation fluctuates (decreases) due to the adhering matter 17, and the monitored temperature apparently decreases. Therefore, the heater 5 is controlled to apply electric power to correct this,
As shown in FIG. 13 (a), the actual growth temperature fluctuates during growth and during Run-to-Run (the number of times of growth), and the growth temperature fluctuates particularly immediately after maintenance. However, regular cleaning was required due to contamination with the deposit 17.

Further, since the material gas is distributed and supplied by using the needle valve 11, the gas flow of the substrate 4 has a distribution such as film thickness and carrier concentration in a region on the downstream side of the reaction furnace. Referring to FIG. 13 in detail, regarding the film thickness,
Since the boundary layer becomes thinner on the downstream side of the wafer, the result shown in FIG.
As shown in, the growth layer thickness also decreases in proportion to this. Regarding the carrier concentration, a large amount of group V atoms with a high decomposition temperature are supplied, so the concentration distribution in the substrate is small, but the group III atoms are consumed and the concentration does not become lower toward the downstream side of the wafer, so the apparent V concentration is lower. As the concentration of group atoms increased,
As shown in FIG. 3 (c), the tendency tends to increase toward the downstream side of the wafer. From the above, there is a problem that the distribution of the growth layer thickness, the carrier concentration, etc. occurs, and the uniformity of the product is deteriorated.

Furthermore, due to the thermal decomposition of the material gas introduced into the reaction furnace from the piping in the upper part of the reaction furnace, the reaction product adheres to the second mesh, and the adhered material causes the mesh to be clogged. There is a problem that the uniformity of the material gas supplied to the substrate is deteriorated, the uniformity of the film thickness of the crystal growing on the substrate, the uniformity of the carrier concentration, etc. are reduced, and maintenance is required to remove this. It was

Further, as described above, the group V material gas such as AsH3 has a high decomposition temperature, so that it is mainly decomposed only on the substrate, and if it is supplied in the same amount as the group III atoms, it will be decomposed on the substrate. The concentration of the group V atom (As atom in the case of arsine) used for the crystal growth is low, so that a large amount of the group V material gas must be introduced during the crystal growth, and the crystal growth of the supplied material gas However, there is a problem that the efficiency (material efficiency) of the product is low.

Incidentally, for example, JP-A-61-248519 and JP-A-60-126823 show an apparatus provided with two exhaust ducts below the reaction furnace. It may be possible to promote the flow of the reaction gas below the susceptor and reduce the deposits below the reaction furnace by adopting the above method. However, with this configuration, it is possible to sufficiently prevent the reaction gas from flowing under the susceptor. In addition, it is not possible to eliminate the uneven distribution of the film thickness and carrier concentration on the upstream and downstream of the reaction gas of the substrate as described above. It had no effect on the clogging of the mesh.

Further, conventionally, in order to remove the deposits deposited in the reactor, it is sufficient to decompose the deposits at the temperature in the reactor while supplying only the carrier gas after completion of the growth or in a vacuumed state. Although a method of heating until reaching a certain temperature has been adopted, such a method has a problem that maintenance time is extremely long and manufacturing efficiency is lowered.

Furthermore, as disclosed in, for example, Japanese Patent Application Laid-Open No. 4-277627 and Japanese Patent Application Laid-Open No. 60-126823, a material for heating a gas shower electrode for ejecting a material gas or a material gas introducing pipe is directly connected. Some of them are designed to be heated, but in these configurations, the material gas is heated before being ejected into the reaction tube, and the flow rate of the material gas in the gas shower electrode and the material gas introduction tube is fast and sufficient heating is achieved. However, there is a problem in that the material gas is decomposed in the gas shower electrode and the material gas introduction pipe, and reaction products adhere to these members to cause clogging.

The present invention has been made to solve the above problems, and it is possible to reduce fluctuations in the growth temperature and to elongate the cleaning cycle of the components in the reaction furnace. It is an object of the present invention to obtain an apparatus, and further to provide a vapor phase crystal growth apparatus capable of performing highly uniform crystal growth.

Further, the vapor phase crystal which can easily and quickly clean the mesh portion below the pipe for introducing the material gas into the reaction furnace and can always supply the material gas uniformly on the substrate. The purpose is to obtain a growth device.

Another object of the present invention is to obtain a vapor phase crystal growth apparatus capable of promoting the decomposition of a material gas having a high decomposition temperature and increasing the material efficiency.

[0018]

In the vapor phase crystal growth apparatus according to the present invention, the exhaust port of the reaction furnace is arranged in the lower part of the reaction furnace, and the detachable cylindrical member is arranged so as to surround the lower part of the heater. It is a thing.

Further, in the vapor phase crystal growth apparatus according to the present invention, while supplying the material gas from the upper part of the reaction furnace, an exhaust port is provided on the side wall of the reaction furnace near the susceptor, and the supplied material gas is exhausted from the vicinity of the susceptor. It is something that is done.

Further, a carrier gas introduction pipe for preventing product adhesion for supplying a carrier gas from the bottom of the reaction furnace to the back side of the susceptor is provided.

Further, in the vapor phase crystal growth apparatus according to the present invention, the material gas is supplied from the upper part of the reaction furnace, and the portion of the wafer arranged on the susceptor which is on the downstream side with respect to the flow of the material gas. In addition, a material gas auxiliary supply pipe for auxiliary supply of the material gas is provided.

Further, in the vapor phase crystal growth apparatus according to the present invention, a heatable mesh is provided between the outlet of the pipe for introducing the material gas into the reaction furnace and the wafer tray or the susceptor for setting the substrate, and at the time of maintenance. The mesh is heated.

Further, in the vapor phase crystal growth apparatus according to the present invention, the material gases having different decomposition temperatures are supplied using different pipes, respectively, and the tip of the material gas supply pipe for supplying the material gas having a high decomposition temperature is supplied. Is placed closer to the substrate side than the tip of the material gas supply pipe that supplies the material gas whose decomposition temperature is lower than this, and a heatable mesh is provided below the tip of each of the above pipes to grow crystals. The material gas having a high decomposition temperature is residual heat or decomposed and supplied to the substrate.

[0024]

In the present invention, since the parts below the susceptor are covered with the tubular member, it is difficult for the material gas to flow into this part.

Further, according to the present invention, since the exhaust port is provided on the side wall of the reaction furnace around the susceptor, the material gas supplied from above the reaction furnace is exhausted from the exhaust port around the susceptor and circulates below the susceptor. It gets harder.

Further, by supplying the carrier gas from the bottom of the reactor toward the back surface of the susceptor, the flow of the material gas into the region below the susceptor is suppressed.

Further, in the present invention, the auxiliary supply of the material gas to the region of the wafer on the downstream side with respect to the flow of the material gas reduces the distribution of the boundary layer in the plane of the wafer.

Further, in the present invention, since the mesh for uniformly spreading the material gas is provided with the heating mechanism and the mesh is heated during the maintenance, the clogging of the mesh can be quickly eliminated.

Further, the material gas having a high decomposition temperature is supplied to the mesh disposed below it by residual heat or thermal decomposition, while the material gas having a decomposition temperature lower than that of the material gas is provided below the mesh. Since the gas is supplied from the position, the concentration of atoms of the material gas having a high decomposition temperature on the wafer is increased, the use efficiency of the material gas is improved, and two gases having different decomposition temperatures reach the wafer. It does not react by the time.

[0030]

【Example】

Example 1. Hereinafter, MOCVD according to the first embodiment of the present invention.
The device will be described with reference to the figures. In FIG. 1, the same reference numerals as those in FIGS. 11 and 12 denote the same or corresponding parts, and a plurality of exhaust ports 1b are provided at the bottom of the reactor 1, and a pipe 1c for introducing hydrogen gas is provided below the rotary shaft 8. And the reactor 1
A detachable cylindrical tube (for example, made of quartz) 17 is attached to the bottom surface of the so as to surround the parts below the heater 5.

Next, the operation of the above apparatus during crystal growth will be described. Since the procedure of crystal growth is the same as that described in the conventional example, only the operation peculiar to this embodiment will be described here. The flow of gas during crystal growth is
As shown in FIG. 1, the heater 5 located below the susceptor 2
Since the heat shield plate 12 surrounds the periphery of the rotary shaft 8 and the like, it is difficult for the parts below the heater 5 to go around, and hydrogen (H2) as a carrier gas is supplied from the pipe 1c on the bottom of the reactor 1. Therefore, the effect of preventing the material gas from flowing around is further improved, and the reaction products are less likely to adhere to the parts below the heater 5. Therefore, fluctuations in thermal radiation due to deposits are reduced, and during growth and Run-to-R
The fluctuation of the growth temperature of un becomes small. In FIG. 1, the pipe 1c is attached so as to supply the gas from the bottom surface of the reaction furnace 1 in a direction perpendicular to the rotating shaft 8. However, since the rotating shaft 8 rotates at high speed during crystal growth, The generated carrier gas flows toward the bottom surface of the susceptor 2 while rotating along the rotation axis 8.

Further, for maintenance, since the outside of the cylindrical tube 17 is mainly contaminated, it is sufficient to take out the cylindrical tube 17 from the inside of the reaction furnace 1 after the growth and wash it. Very easy to maintain.

Since the carrier gas introduced from the pipe 1c is about one sixth of the amount of the material gas and the carrier gas supplied from the upper part of the reaction furnace 1,
It does not adversely affect the flow of the material gas supplied to the substrate 4 during crystal growth.

Example 2. Next, M according to the second embodiment of the present invention.
The OCVD apparatus will be described with reference to the drawings. In FIG. 2, 1
Reference numeral d denotes an exhaust port provided on the side surface of the reaction furnace 1 in the vicinity of the susceptor 3, and a plurality of exhaust ports are provided along the periphery of the reaction furnace 1. Regarding the arrangement of the exhaust port 1d, the wafer tray 3
So that the flow of the material gas supplied to the reactor 3 is as uniform as possible in each region on the tray 3,
It is desirable that at least one pair is provided at a position facing each other, and when a plurality of pairs are provided, they are radially arranged with the center of the wafer tray 3 as a starting point. Also in the second embodiment, similarly to the first embodiment, the pipe 1c is provided so as to introduce the hydrogen gas from the lower side of the rotary shaft 8. In the second embodiment, the wafer tray 3 is also used.
An opening 10 is provided for inserting and removing
It does not appear in the cross section of FIG.

Next, the operation of the above apparatus during crystal growth will be described. Since the procedure of crystal growth is the same as that described in the conventional example, only the operation peculiar to the second embodiment will be described here. The material gas during crystal growth is
As shown in FIG. 2, most of them flow from the center of the surface of the wafer tray 3 along the circumferential direction thereof, and flow into a plurality of exhaust ports 1d provided on the side surface of the reaction furnace 1,
Further, since the carrier gas is introduced from the pipe 1c below the susceptor 2, the wraparound of the material gas below the susceptor 2 is further suppressed, and as a result, reaction products are generated in the parts below the heater 5. It becomes difficult to adhere. Therefore, the fluctuation of the heat radiation due to the deposit is reduced, and the fluctuation of the growth temperature during the growth and the run-to-run becomes small. further,
In this case, since almost no reaction products adhere to the parts inside the reaction furnace 1, maintenance such as cleaning of the parts and the inside of the reaction furnace becomes unnecessary, or the period can be greatly increased. You can expect an effect.

Example 3. Next, M according to the third embodiment of the present invention.
The OCVD apparatus will be described with reference to the drawings. In FIG. 3, 2
Reference numeral 4 denotes an exhaust space formed over the entire inner circumference of the reaction furnace 1 from below the vicinity of the susceptor, and the parts below the susceptor are surrounded by an inner wall 25.

Next, the operation of the above apparatus during crystal growth will be described. Since the crystal growth procedure is the same as that described in the conventional example, only the operation peculiar to the third embodiment will be described here. Carrier gas supply pipe 20
a, each gas supplied from the material gas supply pipes 20b, 20c flows from the center of the wafer tray 3 toward the periphery thereof, uniformly flows from the periphery of the wafer tray 3 toward the exhaust space 24, and is exhausted from the reaction furnace 1. Further, at this time, since the carrier gas is introduced from the pipe 1c below the susceptor 2, the material gas is further suppressed from flowing into the lower portion of the susceptor 2, and as a result, reaction products are generated below the heater 5. It becomes difficult to adhere. Therefore, as in Example 2 above, fluctuations in thermal radiation due to deposits are reduced, fluctuations in growth temperature during growth and in Run-to-Run are reduced, and further maintenance such as cleaning of parts and the inside of the reactor is performed. In addition to the effect that it is unnecessary or the period is significantly increased, the gas is uniformly exhausted from the entire periphery of the wafer tray 3 during exhaust, so that the boundary layer distribution in each substrate 4 is There is an effect that crystals that are improved and more uniform are obtained.

Example 4. Next, M according to the fourth embodiment of the present invention.
The OCVD apparatus will be described with reference to the drawings. In FIG. 4, 1
Reference numeral 9 denotes a material gas auxiliary introduction pipe for introducing a material gas near the wafer tray 3 and above the wafer tray 3 and outside the central portion of the substrate 4 (on the tube wall side), and only one is shown in the drawing. Although not provided, at least one or more introduction tubes 19 are attached to the reaction furnace 1. Also this pipe 19
The other end of is connected to the bubbling device 21. The bubbling device 21 has a carrier gas whose flow rate is controlled by the mass flow controller 22 (here, H 2
2) is supplied so that a predetermined amount of material gas is generated. Other configurations are the same as those shown in the conventional example.

Next, the operation of the above apparatus during crystal growth will be described. In this embodiment, the material gas is the pipe 20.
Since it is supplied from the upper part of the reaction furnace 1 via b and 20c, and is also supplied from the material gas auxiliary introduction pipe 19,
The material gas is also replenished to the outside (downstream portion) of the wafer where boundary distribution is likely to occur, and the uniformity of the growth layer can be easily improved. For example, when the layer thickness distribution of the GaAs growth layer is made uniform, the material gas auxiliary introduction pipe is used. By supplying an appropriate amount of TMG to 19, the uniformity is improved.

Example 5. Next, M according to the fifth embodiment of the present invention.
The OCVD apparatus will be described with reference to the drawings. In the fourth embodiment, the material gas is generated by the bubbling device 21 and is supplied to the material gas auxiliary introduction pipe 19. However, as shown in FIG. 5, in this embodiment, the material to which the required material gas is supplied is supplied. The gas supply pipe is connected to the material gas auxiliary introduction pipe 19 by using the bypass pipe 23 to supply the material gas. Here, the bypass pipe 23 is connected to the material gas supply pipe 20c, and in the middle thereof. Is provided with a needle valve 11. The other parts are the same as in the third embodiment.

With such a structure, the desired material gas can be supplied only by changing the piping without adding a mechanism for separately generating the material gas as in the fifth embodiment. Easy to configure.

Example 6. Next, M according to the sixth embodiment of the present invention.
The OCVD apparatus will be described with reference to the drawings. In FIG. 6, 2
Reference numeral 5 is a mesh heating electrode connected to the second mesh 26, and by applying a voltage to the electrode 25,
The mesh 26 can be heated. FIG. 7 is a diagram showing a detailed configuration of the second mesh 26. As shown in the figure, the second mesh 26 is formed by weaving a resistance wire 26a made of tungsten or the like and an insulating film 26b made of quartz or the like into the resistance wire 26a. Mesh heating electrodes 25 on both ends
With the structure in which the electrodes are connected, heating can be performed by applying a voltage to the electrode 25.

Next, the operation of the above device during crystal growth will be described. The procedure of crystal growth is the same as that of the conventional technique, but the second mesh provided between the material gas supplies 20b and 20c for introducing the material gas into the reaction furnace 1 and the wafer tray 3 for setting the GaAs substrate 4 therein. Since 26 has a structure that can be heated, apart from crystal growth,
The second mesh 26 can be easily cleaned by performing the following operation after crystal growth.

That is, first, GaAs is placed on the wafer tray 3.
The wafer tray 3 is placed on the susceptor 2 in the reaction furnace 1 with the substrate 4 placed thereon, or with nothing placed thereon. Next, hydrogen gas (H2), which is a carrier gas, is introduced into the reaction furnace 1 from the carrier gas supply pipe 20a above the reaction furnace 1, and the pressure in the reaction furnace 1 is set to a desired pressure, for example, 50 Torr.
Alternatively, the inside of the reaction furnace 1 is evacuated without introducing the carrier gas into the reaction furnace 1.

Next, a predetermined voltage is applied to the mesh heating electrode 25 connected to the second mesh 26, and the temperature at which the reaction product is thermally decomposed in the second mesh 26, for example, 300.
By heating to a high temperature of ℃ or more, the second mesh 26
Cleaning is carried out for the desired time. As a result, the reaction product attached to the second mesh 26 is pyrolyzed and removed from the second mesh 26, and the pyrolyzed reaction product is discharged to the outside of the reaction furnace 1 through the exhaust port 1a. At this time, a part of the reaction product thermally decomposed may be scattered on the susceptor and adhere to the susceptor. However, by placing the wafer tray 3 on the susceptor 2 as described above, It is possible to prevent the reaction product from adhering, and the heat of the susceptor 2 is efficiently conducted to the wafer tray 3 when the crystal growth is performed again after the cleaning. Then, after lowering the temperature of the second mesh 26, the wafer tray 3 is taken out from the reaction furnace 1 to prepare for the next crystal growth.

As described above, according to the present embodiment, the second mesh 2 located below the material gas supply pipes 20b, 20c for supplying the material gas and for spreading the jetted material gas.
Since 6 is configured to be heatable, only the second mesh 26 can be quickly and selectively heated at the time of maintenance, the inside of the reaction furnace 1 can be quickly cleaned, and it grows on the substrate 4. Uniformity of crystal film thickness, carrier concentration, etc. is improved.

Example 7. Next, M according to the seventh embodiment of the present invention.
The OCVD device will be described. In the sixth embodiment, at the time of cleaning, the carrier gas is made to flow in the reaction furnace 1 or the second mesh 13 is heated in a vacuum state. However, in this embodiment, as shown in FIG. The second mesh 26 is heated while simultaneously introducing (H2) and an etching gas such as HCl. The configuration is the same as that of the sixth embodiment.

By cleaning the second mesh 26 while introducing the etching gas in this way, the mesh 26 can be cleaned more effectively than in the sixth embodiment.

Although HCl is used as the etching gas in this embodiment, GaAs, I can be changed by appropriately changing the etching gas according to the deposit to be removed.
It is possible to accelerate the removal of deposits made of crystals other than nP.

Example 8. Next, M according to the eighth embodiment of the present invention.
The OCVD device will be described. In the sixth embodiment, as the structure of the second mesh 26, the resistance wire 26a made of tungsten or the like is used.
And an insulating film 26b made of quartz or the like is woven, and the mesh heating electrodes 25 are connected to both ends of the resistance wire 26a.
Instead of the above structure, as shown in FIG. 9, a structure in which a heating electrode 25 is connected to a porous ceramic heater 30 may be used. In short, the temperature can be raised, the corrosiveness is excellent, and the material is Other structures may be used as long as the structure allows gas to pass therethrough.

Example 9. Next, M according to the ninth embodiment of the present invention.
The OCVD apparatus will be described with reference to the drawings. In FIG.
27 is a third mesh provided below the second mesh 24, and has the same configuration as the second mesh 24,
The mesh heating electrode 25 is connected. Reference numeral 20d is a material gas supply pipe whose tip is located between the second mesh 24 and the third mesh 27.

The operation of the MOCVD apparatus configured as above will be described. First, the GaAs substrate 4 is placed in the groove on the wafer tray 3, and the wafer tray 3 is set on the susceptor 2 in the reaction furnace 1. Next, hydrogen gas (H2), which is a carrier gas, is introduced into the reaction furnace 1 from the material gas supply pipe 20a above the reaction furnace 1, and the pressure in the reaction furnace 1 is set to a desired pressure, for example, 50 Torr.

Next, the susceptor 2 is rotated and GaA
In order to suppress thermal decomposition of the substrate 4, the heater 5 is heated while introducing arsine (AsH3), which is a group V material gas, into the reaction furnace 1 from the material gas supply pipe 20b.
The temperature of the GaAs substrate 4 is raised to a desired temperature, for example 700 ° C. At this time, at the same time, the second mesh 24 provided below the material gas supply pipe 20b
A voltage is applied to the electrode 25 connected to the second mesh 2
4 is heated to about 100 to 300 ° C. This makes the second
The AsH3 that has passed through the mesh 24 is preheated, and the decomposition on the GaAs substrate 4 is promoted.
The concentration of As on the substrate 4 increases, and the ratio of materials that are effectively used increases.

Next, a group III material gas such as trimethylgallium (TMG) is introduced from the material gas supply pipe 20d to grow crystals. Here, AsH3 is provided by the second mesh 24 provided below the material gas supply pipe 20b for introducing it into the reaction furnace 1, and TMG is provided below the material gas supply pipe 20d for introducing it into the reaction furnace 1. The third mesh 27 spreads the GaAs evenly.
Reach onto the substrate 4. As a result, the GaAs substrate 4
It is possible to improve the uniformity of the film thickness, composition, and carrier concentration of the GaAs crystal grown above. Also, TMG is the second
Since it is supplied from the material gas supply pipe 20d whose tip is located below the mesh 24, TMG is decomposed by the time it reaches the GaAs substrate 4, reacts with AsH3, and adheres to the third mesh portion 27. Can be prevented.

Next, by stopping the introduction of TMG and suppressing the heating of the heater 5 while flowing AsH3, GaA
The temperature of the substrate 4 is lowered. Next, the heating of the second mesh portion 24 and the introduction of AsH3 are stopped, and the rotation of the susceptor 2 is stopped. Then, finally, the wafer tray 3 is taken out of the reaction furnace 1 and the GaAs substrate 4 on which the crystal has been grown is taken out.

When the reaction product adheres to the mesh 26 and becomes clogged after repeating the growth a predetermined number of times, the mesh heating electrode connected to the third mesh 27 in the same manner as in Example 6 above. Cleaning can be performed by applying a voltage to 25 and heating it. If necessary, a voltage may be applied to the mesh heating electrode 25 connected to the second mesh 24 to heat it.

As described above, according to the present embodiment, the second mesh 24 that can be heated is provided below the material gas supply pipe 20b for supplying AsH3 in the vicinity thereof, while the material gas supply pipe 20d for supplying TMG is supplied. Of the second mesh 24 is extended below the second mesh 24, and a third mesh 27 is provided below the second mesh 24.
Is heated and the decomposition temperature is higher than that of TMG and AsH3 having poor decomposition efficiency is preheated to be supplied to the substrate 4, so that the decomposition of AsH3 on the substrate 4 is promoted,
As a result, the concentration of the group V species on the substrate 4 can be increased, and the proportion of the supplied material gas that is effectively used for crystal growth increases.

TM having a lower decomposition temperature than AsH3
The tip of the material gas supply pipe 20d for supplying G is set to the above-mentioned second
It is located below the mesh 24, and the third
Since the mesh 27 is provided, TMG is decomposed and AsH3 which is left overheated by the second mesh 24 is used.
Does not occur such that the reacts with and adheres to the third mesh 27.

Example 10. Next, an MOCVD apparatus according to Example 10 of the present invention will be described. In the above-mentioned Example 9, the 2nd mesh 24 is 100-300 degreeC during crystal growth.
Although AsH3 having a high decomposition temperature is preheated by heating the second mesh 24, the second mesh 24 may be heated to a high temperature of 700 ° C. or higher to decompose AsH3. In this case, even if AsH3 is decomposed, the temperature of the second mesh portion 24 is sufficiently higher than the decomposition temperature of AsH3, so that the reaction product is less likely to adhere to the second mesh 24. By doing so, the use efficiency of AsH3 can be further improved.

Further, at the time of crystal growth, the temperature of the third mesh 27 is set sufficiently higher than the decomposition temperature of the material gas such as AsH3 and TMG, so that the material supplied from the material gas supply pipe 20d such as TMG. The gas usage efficiency can also be improved. In this case, there is a possibility that the material gases decomposed together in the vicinity of the third mesh 27 may react with each other and these products may easily adhere to the side wall in the reaction furnace 1.

In each of the above embodiments, the case where AsH3 is used as the group V material gas and TMG is used as the group III material gas has been described.
lGaAs, InP, InGaAsP, AlGaInP
With respect to the crystal growth of other material systems such as the above, the same effect as that of the above-described embodiment can be obtained. Further, also in crystal growth other than III-V group crystal growth, the same effect can be expected when two or more kinds of material gases having different decomposition temperatures are used.

In the first embodiment, the exhaust port 1b is provided so that the material gas is exhausted vertically from the bottom surface of the reaction furnace 1. However, the material gas is exhausted horizontally at the bottom surface of the reaction furnace 1. You may provide an exhaust port in.

[0063]

As described above, according to the vapor phase crystal growth apparatus of the present invention, since the parts below the heater are covered with the tubular member, the portion surrounded by the member is not affected. The product is less likely to adhere, the growth temperature stabilizes,
Further, there is an effect that the maintenance inside the reaction furnace becomes easy.

Further, in the vapor phase crystal growth layer according to the present invention, the material gas is exhausted from the periphery of the susceptor, so that the material gas is less likely to flow into the lower portion of the susceptor, so that the reaction product to the lower portion of the susceptor. Adhesion is reduced, the growth temperature is stabilized, and maintenance in the reaction furnace is facilitated.

Further, by supplying the carrier gas from the bottom of the reaction furnace toward the back side of the susceptor, it is possible to further reduce the sneak of the material gas below the susceptor.

Further, according to the vapor phase crystal growth apparatus according to the present invention, the material gas is supplementarily supplied to the portion of the wafer arranged on the susceptor on the downstream side with respect to the flow of the material gas. As a result, the distribution of the boundary layer in the wafer is improved, and there is an effect that a growth layer having high uniformity in film thickness and carrier concentration can be obtained.

Further, according to the vapor phase crystal growth apparatus of the present invention, it is possible to heat the mesh provided between the outlet of the pipe for introducing the material gas into the reaction furnace and the wafer tray or the susceptor for setting the substrate. Since the structure is employed, the mesh can be easily cleaned, the material gas can always be uniformly supplied onto the substrate, and the uniformity of growing crystals can be improved.

Further, according to the vapor phase crystal growth apparatus of the present invention, the pipe for introducing the material gas having a high decomposition temperature is provided above the pipe for introducing the material gas having a decomposition temperature lower than that, and Since a mesh that can be heated is provided in the lower part of the area and the above-mentioned material gas having a high decomposition temperature is supplied to the wafer after residual heat or thermal decomposition, the use efficiency of the material gas having a high decomposition temperature is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a MOCVD apparatus which is a vapor phase crystal growth apparatus according to Example 1 of the present invention.

FIG. 2 is a sectional view showing an MOCVD apparatus which is a vapor phase crystal growth apparatus according to Example 2 of the present invention.

FIG. 3 is a sectional view showing an MOCVD apparatus which is a vapor phase crystal growth apparatus according to Example 3 of the present invention.

FIG. 4 is a sectional view showing an MOCVD apparatus which is a vapor phase crystal growth apparatus according to Example 4 of the present invention.

FIG. 5 is a sectional view showing an MOCVD apparatus which is a vapor phase crystal growth apparatus according to Example 5 of the present invention.

FIG. 6 is a sectional view showing an MOCVD apparatus which is a vapor phase crystal growth apparatus according to Example 6 of the present invention.

FIG. 7 is a diagram showing a structure of a second mesh of the MOCVD apparatus.

FIG. 8 is a sectional view showing an MOCVD apparatus which is a vapor phase crystal growth apparatus according to Example 7 of the present invention.

FIG. 9 is a diagram showing a structure of a porous ceramic heater used in a MOCVD apparatus which is a vapor phase crystal growth apparatus according to Example 8 of the present invention.

FIG. 10 is a sectional view showing an MOCVD apparatus which is a vapor phase crystal growth apparatus according to Examples 9 and 10 of the present invention.

FIG. 11 is a sectional view showing a conventional high speed rotation type MOCVD apparatus.

FIG. 12 is a cross-sectional view of an apparatus for explaining problems of conventional MOCVD.

FIG. 13 is a diagram for explaining a problem of conventional MOCVD.

[Explanation of symbols]

 1 Reactor 1b Exhaust Port 1c Piping 1d Exhaust Port 2 Susceptor 3 Wafer Tray 4 Substrate 5 Heater 6 Heat Shield Plate 7 Heater Electrode 8 Rotating Shaft 9 Thermocouple 10 Opening 11 Needle Valve 12 First Mesh 13 Second Mesh 14 Filter 15 Pressure Adjustment valve 16 Rotary pump 17 Cylindrical cylinder 18 Pressure adjustment valve 19 Material gas auxiliary introduction pipe 20a Carrier gas supply pipe 20b, 20c Material gas supply pipe 20d Material gas supply pipe 21 Bubbling device 22 Mass flow controller 23 Bypass pipe 24 Exhaust space 25 Inner wall 25 Mesh heating electrode 26 Second mesh 26a Resistance wire 26b Insulation wire 27 Third mesh 30 Porous ceramic heater

[Procedure amendment]

[Submission date] December 19, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

Further, the vapor phase crystal growth apparatus according to the present invention supplies with respectively different pipe materials having different gas decomposition temperatures, the material the tip of the gas supply pipe for supplying low have material gas decomposition temperature part of this was placed closer to the substrate side than the tip of the source gas supply pipe for supplying a high not material gas decomposition temperature than provided a mesh heatable lower than the distal end portion of each pipe, The material gas having a high decomposition temperature is heated or decomposed during crystal growth and supplied onto the substrate.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0042

[Correction method] Change

[Correction content]

Example 6. Next, M according to the sixth embodiment of the present invention.
The OCVD apparatus will be described with reference to the drawings. In FIG. 6, 2
Reference numeral 5 is a mesh heating electrode connected to the second mesh 26, and by applying a voltage to the electrode 25,
The mesh 26 can be heated. FIG. 7 is a diagram showing a detailed configuration of the second mesh 26. As shown in the figure, the second mesh 26 is made by weaving a resistance wire 26a made of tungsten or the like and an insulation wire 26b made of quartz or the like into the resistance wire 26a. Mesh heating electrodes 25 on both ends
With the structure in which the electrodes are connected, heating can be performed by applying a voltage to the electrode 25.

[Procedure 3]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

[Figure 8]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yutaka Mitsuhashi 4-1-1 Mizuhara, Itami City, Hyogo Prefecture Mitsubishi Electric Corp. Optical & Microwave Device Development Research Center

Claims (13)

[Claims] 1. A vapor phase crystal growth apparatus for supplying a material gas from the upper part of a reaction furnace, exhausting the material gas from the bottom part of the reaction furnace, and performing crystal growth on a wafer arranged in the reaction furnace, A susceptor on which the wafer is mounted, a heater arranged below the susceptor, for heating the susceptor, and a reactor bottom surface so as to cover the susceptor lower side, and the inflow of the material gas to the lower side of the susceptor. Stop,
An apparatus for vapor phase crystal growth, comprising: a detachable tubular member. 2. A vapor phase crystal growth apparatus for supplying a material gas from the upper part of a reaction furnace to grow crystals on a wafer arranged in the reaction furnace, wherein a susceptor on which the wafer is mounted and a susceptor below the susceptor. A vapor phase crystal growth apparatus comprising: a heater arranged to heat the susceptor; and an exhaust port provided on a side wall of the reactor near the susceptor. 3. The vapor phase crystal growth apparatus according to claim 2, wherein each of the plurality of exhaust pipes connected to the exhaust port has a pressure adjusting mechanism for adjusting the exhaust pressure of the material gas to be exhausted. A vapor phase crystal growth apparatus characterized by: 4. The vapor phase crystal growth apparatus according to claim 2, wherein the exhaust port is constituted by an inner side wall surface of the reaction furnace and a partition wall formed at a predetermined interval over the entire inner circumference thereof. In the vapor phase crystal growth apparatus, the material gas is exhausted to the outside of the reaction furnace through a space between an inner side wall surface of the reaction furnace and a partition wall. 5. The vapor phase crystal growth apparatus according to claim 1, further comprising a carrier gas introduction pipe for introducing a carrier gas from the bottom surface of the reaction furnace toward the back surface of the susceptor,
A vapor phase crystal growth apparatus, characterized in that the material gas is prevented from flowing into the lower side of the susceptor. 6. A vapor phase crystal having a susceptor for mounting a wafer, wherein the material gas supplied from the upper part of the reaction furnace flows from the center to the peripheral side on the susceptor arranged in the reaction furnace. In the growth apparatus, a material gas auxiliary supply pipe for auxiliary supply of a material gas is provided in a portion of the wafer mounted on the susceptor on the downstream side with respect to the flow of the material gas. Crystal growth equipment. 7. The vapor phase crystal growth apparatus according to claim 6, wherein a plurality of material gas supply pipes for supplying the material gas are provided in accordance with the type of the material gas, and the material gas auxiliary supply pipe is A vapor phase crystal growth apparatus, characterized in that the material gas supply pipe for supplying a material gas of the same type as the auxiliary material gas is branched. 8. A vapor phase crystal growth apparatus for supplying a material gas from the upper part of a reaction furnace to grow crystals on a wafer arranged in the reaction furnace, wherein the material gas is supplied to the reaction furnace. A pipe, a mesh arranged below the tip of the material gas supply pipe for uniformly spreading the supplied material gas, and a mesh heating means for heating the mesh are provided. A vapor-phase crystal growth apparatus, characterized in that a reaction product attached to the mesh is removed by heating. 9. The vapor phase crystal growth apparatus according to claim 8, wherein an etching gas for decomposing the reaction product is introduced together with a carrier gas from the material gas supply pipe when the mesh is heated. Growth equipment. 10. The vapor phase crystal growth apparatus according to claim 8, wherein a porous ceramic heater is used for the mesh, and the mesh is heated by applying a voltage to the ceramic heater. Vapor phase crystal growth equipment. 11. A material gas is supplied from the upper part of the reaction furnace,
In a vapor phase crystal growth apparatus for performing crystal growth on a wafer arranged in the reaction furnace, a first material gas supply pipe for supplying a first material gas, and a tip portion thereof for supplying the first material gas. It is placed closer to the wafer side than the tip of the pipe, and has a decomposition temperature of the first
Second material gas supply pipe for supplying a second material gas lower than that of the first material gas and the first material gas supply pipe arranged below the first material gas supply pipe for uniformizing the first material gas supplied from the pipe. A first mesh for expanding the second material gas supply pipe, a second mesh arranged below the second material gas supply pipe for uniformly expanding the second material gas supplied from the pipe, and the first mesh And a heating means for heating the second mesh, wherein the first mesh is heated during crystal growth to preheat the first material gas. apparatus. 12. The material gas is supplied from the upper part of the reaction furnace,
In a vapor phase crystal growth apparatus for performing crystal growth on a wafer arranged in the reaction furnace, a first material gas supply pipe for supplying a first material gas, and a tip portion thereof for supplying the first material gas A second material gas supply pipe that is located closer to the wafer than the tip of the pipe and supplies a second material gas whose decomposition temperature is lower than that of the first material gas; and the first material gas supply pipe. A first mesh for uniformly spreading the first material gas supplied from the pipe, and a second mesh provided below the second material gas supply pipe and supplied from the pipe. A second mesh for uniformly spreading the second material gas, and a heating mechanism for heating the first and second meshes, the first mesh being used for the first material during crystal growth. By heating it to a temperature higher than the decomposition temperature of the gas By decomposing the first material gas vapor phase crystal growth apparatus is characterized in that so as to supply on the wafer. 13. The vapor phase crystal growth apparatus according to claim 11 or 12, wherein the second mesh is heated when the apparatus is cleaned to remove a reaction product attached to the mesh. Crystal growth equipment.