JP4641268B2 - Vapor growth apparatus and vapor growth method - Google Patents

Description

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

  As a method for manufacturing semiconductor devices such as light emitting diodes (LEDs) and semiconductor lasers, compound semiconductors using organic metal gases such as trimethylgallium (TMG) and trimethylaluminum (TMA) and hydrogen compounds such as ammonia, phosphine and arsine as raw materials A vapor phase growth method using a metal organic chemical vapor deposition method (abbreviated as MOCVD method) for forming a thin film has been performed. In the MOCVD method, the aforementioned raw materials are introduced into a reaction furnace, mixed, and subjected to a thermochemical reaction on the substrate to be processed to form a thin film on the substrate to be processed.

  As one of vapor phase growth apparatuses using the MOCVD method, there is a horizontal MOCVD apparatus. A horizontal MOCVD apparatus is a device in which a reaction tube is provided in a reaction furnace in a horizontal direction, and a gas is introduced into the reaction tube in a horizontal direction to react with the substrate to be processed placed on the reaction tube. is there. Such a horizontal MOCVD apparatus has an advantage that the gas flow is in a laminar flow along the surface on which the substrate to be processed is formed, and the in-plane uniformity of film thickness and film quality is good. Therefore, the horizontal MOCVD method is generally widely used.

  FIG. 16 is a schematic diagram illustrating a configuration around a reaction furnace 2 of a conventional typical horizontal MOCVD apparatus 1. In a conventional horizontal MOCVD apparatus 1, a rectangular tube-like reaction tube 3 is provided through a reaction furnace 2 in the horizontal direction. The reaction tube 3 is made of quartz or the like, and has one end that faces the outside of the reaction furnace 2 and opens to constitute a gas inlet 4 for introducing a gas containing a film forming raw material component into the reaction tube 3. The other end of the gas outlet 5 faces the outside of the reaction furnace 2 and opens to constitute a gas exhaust port 5 for discharging the gas containing the film forming raw material component out of the reaction tube 3.

  A susceptor 7 on which the substrate 6 to be processed is placed is provided at a substantially central portion in the longitudinal direction of the reaction tube 3. A heater 8 for heating the substrate 6 to be processed is provided below the susceptor 7. When forming a film on the surface of the substrate 6 to be processed, gas is introduced into the reaction tube 3 in the direction indicated by the arrow 9 from the gas inlet 4, and the substrate 6 to be processed is heated by the heater 8 provided below the susceptor 7. Heating is performed to promote a film forming reaction to form a thin film on the substrate 6 to be processed. The gas used for forming the thin film and passing over the substrate 6 to be processed is discharged from the gas exhaust port 5 in the direction of the arrow 10.

  In such a conventional horizontal MOCVD apparatus 1, as described above, the gas introduced into the reaction tube 3 during film formation is heated around the substrate 6 to be processed by the heater 8 and the susceptor. A thin film is formed on the substrate 6 by being heated indirectly by 7 and promoting a thermochemical reaction. Therefore, the gas is supplied into the reaction tube 3 at a predetermined concentration, that is, at a constant gas flow velocity distribution, and the temperature state is always uniform on the substrate 6 to be processed. Are the conditions necessary for forming a good thin film having a uniform composition and film thickness. In production sites where product quality is important, such as semiconductor devices, it is extremely important to maintain a stable yield for a long period of time, and how to improve process reproducibility. It has become a challenge.

  However, in the conventional horizontal MOCVD apparatus 1, since the infrared rays radiated from the heater 8 pass through the quartz reaction tube 3, heat is released to the outside of the reaction tube 3, and the utilization efficiency of the heat energy from the heater 8 is increased. Very low. For this reason, the uniformity of the quality and thickness of the film formed on the substrate 6 to be processed is hindered. In the film forming step of growing the film forming raw material components on the substrate to be processed in the conventional horizontal MOCVD apparatus 1, a by-product of the gas phase reaction adheres to the inner wall of the reaction tube 3.

  FIG. 17 is a schematic diagram showing a state in which the by-product 11 adheres to the inner wall of the reaction tube 3 in the film forming step. A gas containing a film forming raw material component is introduced into the reaction tube 3 in the direction indicated by an arrow 9 from the gas inlet 4 and the substrate 6 to be processed is heated by the heater 8 provided below the susceptor 7. A thin film is formed on the processing substrate 6. At this time, the residual gas that has not been used for forming the thin film moves to the downstream side in the gas flow direction of the reaction tube 3 while floating, and a part of the residual gas has a composition until it is discharged from the gas exhaust port 5. It becomes an incomplete by-product 11 and adheres to the inner wall of the reaction tube 3. Hereinafter, the by-product 11 attached to the inner wall of the reaction tube 3 is referred to as an attached matter.

  The deposit 11 formed in this way is deposited as the vapor phase growth is repeated, and the adhesion region gradually expands. The area of the adhesion region is the type of gas, the flow rate of the gas, the dimensions of the reaction tube 3, It becomes a stable size determined according to the temperature distribution inside the reaction tube 3 and the thin film formation conditions. Here, since the deposit 11 has a higher infrared absorptivity than the reaction tube 3 made of quartz, the temperature distribution inside the reaction tube varies greatly before and after the deposit 11 is formed. When the temperature distribution inside the reaction tube 3 changes, it becomes difficult to form a uniform thin film on the substrate 6 to be processed. For this reason, the deposition step of performing dummy deposition on the substrate to be processed until the deposit 11 adheres to some extent inside the reaction tube 3, the temperature inside the reaction tube 3 is stabilized, and process reproducibility can be secured. It is necessary to perform a pre-processing of performing

  This pretreatment needs to be performed at least five times, although it depends on the process conditions such as the type of gas containing the film forming raw material component, the gas introduction speed, the size of the reaction tube 3, and the heating temperature of the heater 8. There is. Further, as the number of pretreatments increases, deposits accumulate on the inner wall of the reaction tube 3 and the thickness of the deposits increases.

  FIG. 18 is a diagram showing the relationship between the number of processes, which is the number of times one substrate is processed by the horizontal MOCVD apparatus 1 shown in FIG. 16, and the thickness of the deposit. According to FIG. 18, when the process is performed n1 times, the adhesion region of the deposit is stabilized, and film formation (production) on the substrate 6 to be processed as a product can be performed.

  However, when the number of processes reaches n2, the thickness of the deposit becomes t2, and the weight of the deposit 11 increases. For example, when the deposit 11 adheres to the upper side of the inner wall of the reaction tube 3, the increase occurs. The deposit 11 falls due to its own weight or the like, and a part of the deposit 11 is peeled off. Moreover, the deposit | attachment 11 becomes an obstacle with respect to the gas which flows through the reaction tube 3, and peeling arises in a part of the deposit | attachment 11 with the wind pressure of gas.

  When the deposit 11 is peeled off, the quartz constituting the reaction tube 3 is exposed in the peeled region, and the temperature inside the reaction tube 3 is locally reduced. Further, the peeled deposit 11 falls on the substrate 6 to be processed, and a foreign matter defect is generated as a product.

  Therefore, it is necessary to perform maintenance to remove the deposit 11 formed on the inner wall of the reaction tube 3 until the number of normal processes reaches n2. This maintenance takes several hours, and since the number of processes from the stabilization of the adhesion region of the deposit 11 until the deposit 11 is peeled off is about 10 times, After performing the pretreatment for forming the dummy film, the maintenance must be performed every time the process is performed 10 times. For this reason, there is a problem that the production efficiency is extremely deteriorated and the cost is increased.

  In view of this, a vapor phase growth apparatus that can always keep the temperature distribution inside the reaction tube constant even at the initial stage of the process and when the deposits are peeled off has been proposed ( For example, see Patent Document 1).

  The vapor phase growth apparatus disclosed in Patent Document 1 is provided with infrared absorption means so as to be in contact with the inner wall or the outer wall of the reaction tube. In the vapor phase growth apparatus disclosed in Patent Document 1, by making the infrared absorption rate of the infrared absorption means substantially equal to the infrared absorption rate of the deposit, the deposit is peeled off even at the initial stage of the process. In addition, the temperature state in the reaction tube can be made uniform, and the film can be stably formed on the substrate to be processed. For this reason, it is not necessary to perform pretreatment before film formation on the substrate to be processed as a product, and the temperature distribution inside the reaction tube does not change greatly between before and after the removal of the deposit, so that stable formation can be achieved. It is said that the film can be performed.

  However, since the amount of infrared absorption of the deposit varies depending on the thickness, density, etc. of the deposit, the infrared absorptivity of the infrared absorbing means and the deposit is equalized as in the vapor phase growth apparatus disclosed in Patent Document 1. However, these infrared absorption amounts are not necessarily equal. As long as there is a difference in the amount of infrared absorption between the deposit and the infrared absorbing means, a change in temperature distribution inside the reaction tube due to the peeling of the deposit is inevitable.

  In addition, the infrared absorption means provided in the vapor phase growth apparatus disclosed in Patent Document 1 does not actually provide a temperature increase enough to suppress the formation of deposits, and the amount of deposits formed is a conventional MOCVD apparatus. 1 is the same as the amount of deposits formed. That is, in the vapor phase growth apparatus disclosed in Patent Document 1, it is not necessary to perform the pretreatment, but the maintenance needs to be performed at the same time as the conventional horizontal MOCVD apparatus 1. Since the formation of deposits on the inner wall of the reaction tube is inevitable in the vapor phase growth apparatus, in order to improve the production efficiency, the maintenance time is delayed, that is, the deposit is formed on the inner wall of the reaction tube. It is desirable to reduce the amount.

  Furthermore, especially when the infrared absorption means is provided on the inner wall of the reaction tube, the flow velocity distribution of the gas is affected by the difference in the surface material such as the step shape of the reaction tube inner wall surface and the surface roughness due to the provision of the infrared absorption means. Disturbance may occur, which may adversely affect film formation on the substrate to be processed. Even if infrared absorbing means is provided on the inner wall of the reaction tube, the heating efficiency is still not sufficient, and further improvement in heating efficiency is required.

Japanese Patent No. 3104677

  The object of the present invention is to increase the heating efficiency to the gas containing the film forming raw material component, and to increase the production efficiency by reducing the amount of deposits formed on the inner wall of the reaction tube, and onto the substrate to be processed. It is an object to provide a vapor phase growth apparatus and a vapor phase growth method capable of uniformly forming the film.

The present invention introduces a gas containing a film forming raw material component into a reaction tube in which a substrate to be processed is accommodated so as to flow in a direction along a surface of the substrate to be processed, and the introduced gas is heated. in the vapor phase growth apparatus for growing on a substrate to be processed to film-forming ingredients while the reaction by in heating,
Infrared reflecting means provided so as to be in contact with the outer wall surface of the reaction tube, reflecting infrared rays, and changing the infrared reflectance within the surface in contact with the outer wall surface of the reaction tube ,
Said infrared reflecting means is provided in contact with the reaction tube outer wall surface, a sheet-like infrared reflecting member through-hole is formed a vapor deposition apparatus characterized by including Mukoto.

In the present invention, the infrared reflecting means is
It is characterized in that it is provided so as to be in contact with the outer wall surface of the reaction tube over the adhesion region of the deposits adhering to the inner wall of the reaction tube.

In the present invention, the infrared reflecting means is
The infrared reflectivity changes so that the infrared reflectivity increases as the distance from the heating means increases.

Or the invention, the outer wall surface of the reaction tube target substrate is accommodated, comprising: providing a infrared reflecting means for reflecting infrared radiation, in a plane of the side in contact with the outer wall surface of the reaction tube, infrared reflectance A step of providing an infrared reflecting means including a sheet-like infrared reflecting member in which a through hole is formed ;
A gas introduction step for introducing a gas containing a film forming raw material component into the reaction tube so as to flow in a direction along the surface of the substrate to be formed;
And a film forming step of growing a film forming raw material component on a substrate to be processed while reacting by introducing a gas to be introduced.

The present invention also provides a step of providing infrared reflecting means on the outer wall surface of the reaction tube.
Infrared reflecting means
It is characterized by being provided over the adhesion area of the deposits that adhere to the inner wall of the reaction tube.

According to the present invention, a gas containing a film forming raw material component is introduced into a reaction tube in which a substrate to be processed is accommodated so as to flow in a direction along a surface on which the substrate to be processed is formed. In a vapor phase growth apparatus for growing a film forming raw material component on a substrate to be processed while being reacted by heating with a heating means, an infrared reflecting means for reflecting infrared rays is provided so as to be in contact with an outer wall surface of a reaction tube. The deposit formed as a by-product of the gas phase reaction is not easily formed at a location where the inner wall surface of the reaction tube is at a high temperature. Therefore, by providing infrared reflection means so as to be in contact with the outer wall surface of the reaction tube, the inner wall of the reaction tube can be heated and heated to reduce the amount of deposits formed on the inner wall of the reaction tube. Further, by providing the infrared reflecting means, the gas can be heated with high heating efficiency even in the initial stage of film formation. Furthermore, since the infrared reflecting means is provided in contact with the outer wall surface of the reaction tube, the film can be formed on the substrate to be processed without disturbing the gas flow velocity distribution inside the reaction tube. A film can be formed. Therefore, the heating efficiency of the gas containing the film forming raw material component can be increased, and the production efficiency can be increased by reducing the amount of deposits formed on the inner wall of the reaction tube. In addition, it is possible to suppress the occurrence of uneven thickness in the thin film formed on the substrate to be processed, and it is possible to form a thin film having a uniform thickness with good reproducibility.
In addition, since the infrared reflectance of the infrared reflecting means changes within the surface on the side in contact with the outer wall surface of the reaction tube, for example, the infrared reflectance of a region where the amount of deposits adhering to the inner wall of the reaction tube is large is increased. By reducing the infrared reflectance in the region where the amount of deposits adhering to the inner wall of the reaction tube is low, the formation rate of deposits formed on the inner wall of the reaction tube can be made uniform.
The infrared reflecting means includes a sheet-like infrared reflecting member provided in contact with the outer wall surface of the reaction tube. As the infrared reflecting means, for example, a sheet-like infrared reflecting member such as a film or a thin plate is used. Therefore, it is possible to prevent an increase in the size of the vapor phase growth apparatus by providing the infrared reflecting means. Further, since a sheet-like member having a simple shape can be used as the infrared reflecting means, the cost is not affected, and the workability is improved in installing and maintaining the infrared reflecting means in the reaction tube.
In addition, a through hole is formed in the infrared reflecting member. As a result, infrared rays can be emitted from the through-hole portion to the outside of the reaction tube, so that temperature distribution can be suppressed from occurring inside the reaction tube, and a thin film having a uniform thickness can be formed on the substrate to be processed. .

  Further, according to the present invention, the infrared reflecting means is provided so as to be in contact with the outer wall surface of the reaction tube over the attachment region of the deposit attached to the inner wall of the reaction tube. By providing the infrared reflecting means over the adhesion region of such an adhering substance, the film forming conditions in the vicinity of the substrate to be processed become stable, and a thin film having a uniform thickness can be formed with higher reproducibility.

  Further, according to the present invention, the infrared reflectance of the infrared reflecting means changes so that the infrared reflectance increases as the distance from the heating means increases. In a region far from the heating means, the temperature is low and deposits are likely to be formed, and in a region near the heating means, the temperature is high and deposits are difficult to form. Therefore, as described above, the infrared reflectance is increased in the region of the inner wall of the reaction tube where deposits are likely to adhere by changing the infrared reflectance so that the infrared reflectance increases as the distance from the heating means increases. Since the infrared reflectance can be lowered in the region of the inner wall of the reaction tube where the deposits are difficult to adhere, the thickness unevenness of the deposit formed on the inner wall of the reaction tube can be reduced. This also eliminates the disturbance of the gas flow velocity distribution inside the reaction tube and the temperature distribution inside the reaction tube, so that film formation on the substrate to be processed can be performed more uniformly.

Further, according to the present invention, there is provided a step of providing infrared reflecting means for reflecting infrared rays on the outer wall surface of the reaction tube in which the substrate to be processed is accommodated , and the infrared reflection is performed within the surface in contact with the outer wall surface of the reaction tube. A step of providing an infrared reflecting means including a sheet-like infrared reflecting member in which a rate changes and a through hole is formed, and a gas containing a film forming raw material component in a reaction tube along the surface of the substrate to be formed By a vapor phase growth method including a gas introduction step for introducing a gas flow in a direction and a film formation step for growing a film forming material component on a substrate to be processed while reacting by heating the introduced gas. Film formation is performed on the processing substrate. Thus, the gas can be heated with high heating efficiency, and the amount of deposits formed on the inner wall of the reaction tube can be reduced to increase production efficiency, and uniform film formation on the substrate to be processed can be performed.

  Further, according to the present invention, in the step of providing the infrared reflecting means on the outer wall surface of the reaction tube, the infrared reflecting means is provided over the attachment region of the deposit attached to the inner wall of the reaction tube. By providing the infrared reflecting means over at least such a region, the amount of deposits formed in the film forming step can be reduced, and film formation can be performed with high heating efficiency.

  The present invention introduces a gas containing a film forming raw material component into a reaction tube in which a substrate to be processed is accommodated so as to flow in a direction along a surface of the substrate to be processed, and the introduced gas is heated. A vapor phase growth apparatus for growing a film-forming raw material component on a substrate to be processed while being heated by reaction, and is provided so as to be in contact with an outer wall surface of a reaction tube, and includes an infrared reflecting means for reflecting infrared rays Is a vapor phase growth apparatus characterized by

Figure 1 is a sectional view seen from the side schematically showing the configuration around the reaction furnace 21 of the vapor phase growth apparatus 20, FIG. 2 is a top view of the reaction tube 23 of the infrared reflecting means 22 is provided. The vapor phase growth apparatus 20 generally includes a reaction furnace 21, a reaction tube 23, a susceptor 25 on which a substrate to be processed 24 is placed, a heater 26 that is a heating unit provided below the susceptor 25, and a reaction tube 23. Infrared reflecting means 22 is provided so as to be in contact with the outer wall surface and reflects infrared rays. Although the vapor phase growth apparatus 20 includes a temperature sensor provided in the vicinity of the substrate to be processed 24 and a control unit that controls the operation of the heater 26, the illustration is omitted. Examples of the vapor phase growth apparatus 20 include a semiconductor processing apparatus used for performing a thin film forming process on a semiconductor substrate.

  The reaction furnace 21 is a casing having a rectangular parallelepiped shape, and is formed by lining a refractory or the like on a metal grain, for example. Through-holes are respectively formed at opposing positions on the wall surfaces facing both ends of the reaction furnace 21 in the longitudinal direction, and the reaction tube 23 is inserted into the through-holes. The reaction tube 23 has a rectangular tube shape and is made of a heat-resistant material such as quartz or alumina.

  In the reaction tube 23, a gas containing a film forming raw material component for forming a film on the film forming surface of the substrate to be processed 24 is supplied from the gas inlet 27 at one end to the surface to be processed of the substrate to be processed 24. The gas used in the film forming process is exhausted in the direction of the arrow 30 through the gas exhaust port 29 which is the other end.

  The gas supply to the gas inlet 27 of the reaction tube 23 includes a gas supply source such as a high-pressure cylinder, a pressure / flow rate adjusting valve connected to the gas supply source, and a gas supply connected to the gas supply source and the reaction tube 23. Although it is performed by a gas supply means including a pipe line, the illustration of the gas supply means is omitted.

  In the reaction tube 23, the reaction tube 23 is attached to the reaction furnace 21, and an opening 31 is formed on the side (lower side) facing the bottom surface portion 21 a of the reaction furnace 21 and at a substantially central portion in the longitudinal direction. . A heater 26 is provided at a portion where the opening 31 is formed so as to rise from the bottom surface 21 a of the reaction furnace 21. The heater 26 is made of, for example, a resistance heating element, and is rotatably provided by a rotation driving unit (not shown). The heater 26 can be heated by being supplied with power from a power source (not shown). A susceptor 25 is mounted on the heater 26. The susceptor 25 is a holding member and can hold the substrate to be processed 24 placed thereon. By supplying electric power to the heater 26 to generate heat and rotating it, the susceptor 25 is heated and rotated, and the substrate to be processed 24 placed on the susceptor 25 is heated and heated while rotating in the reaction furnace 21. Is done.

The infrared reflecting means 22 is provided in contact with the outer wall surface of the reaction tube 23. As the infrared reflecting means 22, for example, a high melting point metal material such as molybdenum, stainless steel, nickel, titanium, or chromium, a thin plate of an alloy, or the like can be used . Infrared reflecting means 22, over the attachment region of the deposits adhering to the inner wall of the reaction tube 23, provided in contact with the outer wall surface of the reaction tube 23, so as to be in contact with the upper surface of the top member 23a of the reaction tube 23 Provided.

  Here, the adhering matter adhering to the inner wall of the reaction tube 23 is, for example, a reaction tube while a residual gas that has not been used for forming a thin film in a film forming step for growing a film forming raw material component on the substrate to be processed 24 23, a part of which becomes an incomplete by-product in the composition and moves to the downstream side of the gas exhaust port 29 and adheres to the inner wall of the reaction tube 23. Since such a deposit has a higher infrared absorption rate than a material such as quartz constituting the reaction tube 23, the temperature distribution inside the reaction tube 23 greatly changes before and after the formation of the deposit, and is uniform. Formation of a thin film becomes difficult.

The adhesion area of the deposit that adheres to the inner wall of the reaction tube 23 is determined as follows. For example, the deposit region is a vapor phase growth apparatus having the same configuration as the vapor phase growth apparatus 20 except that the infrared reflecting means 22 is not provided, and a predetermined temperature and a gas flow rate in the reaction tube 23 are used. It is obtained by carrying out a film forming process for forming a thin film on the substrate 24 to be processed according to thin film forming conditions such as gas concentration and gas phase reaction simulation.

  FIG. 3 is a diagram showing the relationship between the number of film forming processes and the area of the attached region of the attached matter. As shown in FIG. 3, the adhesion area of the deposit is stable depending on the type of gas containing the film forming raw material component, the gas flow rate, the dimensions of the reaction tube 23, the temperature distribution inside the reaction tube 23, the thin film formation conditions, and the like. Convergence to the area size S and the area of stable shape.

FIG. 4 is a cross-sectional view of the reaction tube 23 in which the film forming process is performed using the vapor phase growth apparatus having the same configuration as the vapor phase growth apparatus 20 except that the infrared reflection means 22 is not provided, and the deposit 32 is adhered. FIG. 5 is a view of the upper surface member 23a of the reaction tube 23 shown in FIG. 4 as viewed from the susceptor 25 side. Since the gas phase reaction proceeds from the upstream side to the downstream side in the gas flow direction of the susceptor 25 heated by the heater 26, the adhering matter 32 extends from near the susceptor 25 to the downstream side of the upper surface member 23 a of the reaction tube 23. It is formed.

  The adhesion area of the deposit can be obtained in advance by performing a film forming process until the area of the deposit area of the deposit becomes a stable size S, and the area where the infrared reflection means 22 is provided is the obtained adhesion area. Is set on the outer wall surface of the reaction tube 23 accordingly.

  Hereinafter, the film forming operation on the substrate to be processed 24 by the vapor phase growth apparatus 20 will be described. At the time of film formation, first, a gas containing a film forming raw material component is introduced into the reaction tube 23 from the gas inlet 27. The gas introduced into the reaction tube 23 from the gas inlet 27 and reaching the vicinity of the substrate to be processed 24 is warmed by radiant heat radiated from the heater 26 via the susceptor 25 and the substrate to be processed and heat conduction in the gas. A thin film is formed on the substrate 6 to be processed by promoting the thermochemical reaction.

  According to the vapor phase growth apparatus 20, since the infrared reflecting means 22 is provided, the infrared light transmitted through the reaction tube 23 is reflected by the infrared reflecting means 22 and is used again for raising the temperature in the reaction tube 23. Accordingly, high heating efficiency can be obtained, and the gas can be heated with high heating efficiency even in the initial stage of film formation.

6, when using a horizontal MOCVD apparatus 1 having no infrared reflective means shown in vapor phase growth apparatus 20 and 16 Ru provided an infrared reflecting means 22, to reach a temperature at which the temperature of the target near the substrate is predetermined It is a figure which shows the result of having measured each required time. A line 33 indicates the time required for the temperature in the vicinity of the substrate to be processed 24 to reach a predetermined temperature when using the horizontal MOCVD apparatus 1 that does not include infrared reflecting means. A line 34 indicates the vapor phase growth apparatus 20. The time required for the temperature near the substrate to be processed 24 when used to reach a predetermined temperature is shown.

  Note that the time required for the temperature in the vicinity of the substrate to be processed to reach a predetermined temperature is the time required for the film formation temperature to be a predetermined temperature from a normal temperature (25 ° C.) state. The film forming temperature is determined by the type of film forming raw material and the like, and is a temperature necessary for causing the film forming raw material to undergo a thermochemical reaction. Note that the time required for temperature increase is that the temperature of the reaction tube is lowered to room temperature at the end of each film formation process, then the next film formation process is performed, and the time required for temperature increase in each film formation process is measured. This is the value obtained.

  As shown by the line 33 in FIG. 6, in the horizontal MOCVD apparatus 1 that does not include the infrared reflecting means, it takes a long time (T1) to raise the gas temperature to a predetermined temperature in the first film formation process. Thereafter, each time the film formation process was repeated, the temperature rising time became shorter and converged to a certain value (T2). That is, in the horizontal MOCVD apparatus 1 that does not include the infrared reflecting means, the temperature can be raised stably in a short time after the adhesion region of the deposit 32 is stabilized. It can be seen that the loss of heat energy is large. For this reason, it is necessary to perform pretreatment until the temperature distribution in the reaction tube 23 is stabilized.

On the other hand, as shown in line 34 of FIG. 6, the vapor phase growth apparatus 20 Ru provided an infrared reflecting means 22, less time from the first time of the process to increase the temperature, needed to raise the temperature be repeated deposition process The time did not change. That is , in the vapor phase growth apparatus 20, since the temperature rise time does not change even during the first process or after a large number of film formation processes, no pretreatment is required and high production efficiency can be obtained. In addition, a thin film having a uniform thickness can be formed with good reproducibility.

  FIG. 7 is a diagram showing the relationship between the number of processes, which is the number of times the substrate to be processed is processed by the vapor phase growth apparatus 20 shown in FIG. As shown in FIG. 7, when the substrate to be processed is processed by the vapor phase growth apparatus 20, n2 times of film forming processes are started when the deposit 32 starts to peel off when using the above-described horizontal MOCVD apparatus 1 not provided with infrared reflection means. Even if it implements, the thickness of the deposit | attachment 32 is smaller than t2 which is the thickness from which the deposit | attachment 32 begins to peel. The amount of the deposit 32 is reduced in this way because the deposit 32 formed as a by-product of the gas phase reaction is less likely to be formed at a location where the inner wall surface of the reaction tube 23 is at a high temperature. It is considered that this is because the temperature of the inner wall of the reaction tube 23 is increased by providing the infrared reflecting means 22 so as to be in contact with the outer wall surface. Since the amount of deposit 32 is reduced, the maintenance time interval for removing the deposit 32 formed on the inner wall of the reaction tube 23 can be increased and the frequency thereof can be reduced. Can be improved.

  Further, the infrared reflecting means 22 is provided in contact with the outer wall surface of the reaction tube 23. For example, when the infrared reflecting means 22 is provided in contact with the inner wall surface of the reaction tube 23, the gas flow velocity distribution in the reaction tube 23 changes. However, in the vapor phase growth apparatus 20 of the present invention, the infrared reflecting means 22 is used. Is provided in contact with the outer wall surface of the reaction tube 23, so that a film having a uniform thickness can be formed on the substrate to be processed 24 without disturbing the flow velocity distribution of the gas inside the reaction tube 23.

  Note that the vapor phase growth apparatus 20 is not limited to the above-described configuration, and various modifications can be made. For example, the infrared reflecting means 22 is not limited to being provided only over the attachment region of the attached matter 32, and may be provided as long as it is in contact with the outer wall surface. However, by providing the infrared reflecting means 22 over the adhesion region of the deposit 32, the temperature distribution in the reaction tube 23 becomes good and the film forming conditions in the vicinity of the substrate to be processed can be stabilized, so that the thickness is uniform. The thin film can be formed with higher reproducibility.

  If the area and shape of the portion where the infrared reflecting means 22 is provided are too small compared to the area of the adhered region of the deposit 32, the adhered region has not yet been fixed. The temperature distribution (of gas) in the vicinity of the substrate to be processed may change, and a thin film having a uniform thickness may not be formed with good reproducibility. Further, if the area of the portion where the infrared reflecting means 22 is provided is too large compared to the area of the attached region of the deposit 32, the high temperature region in the reaction tube 23 is expanded and optimally controlled near the substrate to be processed. There is a possibility that conditions for film formation to be performed, for example, conditions such as gas temperature, gas concentration, and gas flow rate, may be deviated from the installation position of the substrate to be processed.

  For example, when the entire reaction tube 23 is covered with the infrared reflecting means 22, the gas reaction starts at a portion closer to the gas introduction port 27 than the substrate to be processed, and the gas is heated and reacted until it reaches the substrate to be processed. Becomes longer. As a result, the film formation conditions that should be optimally controlled near the substrate to be processed shift to a portion closer to the gas inlet 27 than the substrate to be processed, so that high-quality film formation can be performed on the substrate to be processed. May not be obtained.

In addition, as described above, the deposition region of the deposit 32 is a vapor phase growth apparatus having the same configuration as the vapor phase growth apparatus 20 except that the infrared reflection means 22 is not provided , and the vapor phase growth apparatus 20 is used. The film forming process is not limited to be performed under the same thin film forming conditions as those described above, and may be predicted by, for example, simulation.

FIG. 8 is a plan view schematically showing the configuration of the infrared reflecting means 40 provided in the vapor phase growth apparatus. Vapor deposition apparatus of this, instead of the infrared reflecting means 22, as the away from the heater 26 is a heating means, except that the infrared reflecting means 40 for infrared reflectance is high is provided, above the gas phase Since it is similar to the growth apparatus 20, the entire configuration diagram is omitted, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

Infrared reflecting means 40 is in the plane of the side in contact with the outer wall surface of the reaction tube 23, wherein the infrared reflectance is changed. More specifically, the infrared reflecting means 40, first to sixth infrared reflective portion 41a of the plurality of infrared reflectance provided in contact with the outer wall surface of the reaction tube 23 is different (six in this form state), 41b, 41c, 41d, 41e, 41f (hereinafter collectively referred to as the infrared reflection part 41 except for the case where a specific infrared reflection part is shown), and the infrared reflectance of the infrared ray reflectivity as it is separated from the heater 26 as the heating means The high infrared reflective part 41 is arrange | positioned, It is characterized by the above-mentioned.

Infrared reflecting means 40, like the infrared reflecting means 22 described above, and the like, for example, a metal thin plate. The infrared reflecting means 40 is adjusted so that the infrared reflectance is different within the surface in contact with the outer wall surface of the reaction tube 23. The adjustment of the infrared reflectance can be realized by, for example, partially changing the surface state by a processing method such as matting, mirror surface processing, or irregular reflection processing.

The infrared reflecting portion 41 indicates a divided area of the infrared reflecting means 40 determined according to the reflectance of the infrared reflecting means 40 . Infrared reflecting portion 41, for example, the first infrared reflective portion 41a, a second infrared reflective portion 41b, a third infrared reflective portion 41c, a fourth infrared reflective portion 41d, the fifth infrared reflective portion 41e, a sixth infrared reflective portion 41f Are defined by the following six areas. The infrared reflection unit 41 is arranged in the order from the heater 26, the first infrared reflection unit 41a, the second infrared reflection unit 41b, the third infrared reflection unit 41c, the fourth infrared reflection unit 41d, the fifth infrared reflection unit 41e, and the sixth infrared ray. A reflection part 41f is defined. In addition, the infrared reflection unit 41 has the first infrared reflection unit 41a, the second infrared reflection unit 41b, the third infrared reflection unit 41c, the fourth infrared reflection unit 41d, the fifth infrared reflection unit 41e, Six infrared reflection parts 41f are defined.

  In order to explain the effects obtained by using such an infrared reflecting means 40, first, the thermal energy distribution received from the heater 26 of the reaction tube 23, the flow velocity distribution in the reaction tube 23, and the attachment formed in the reaction tube 23. The state of the kimono 32 will be described.

FIG. 9 is a diagram showing the reaction tube 23 and the thermal energy distribution received from the heater 26 of the upper surface member 23a of the reaction tube 23 when the surface orthogonal to the gas flow direction is viewed as a cross section. The thermal energy of the reaction tube wall surface indicated by the vertical axis in FIG. 9 is the thermal energy received by the quartz constituting the reaction tube 23 from the heater 26, and when the reaction tube 23 and the heater 26 are regarded as black bodies, It is the heat energy calculated from the radiation heat transfer calculation formula between two surfaces. The formula for calculating radiant heat transfer is shown in the following formula (1).
Q = (EB1-EB2) × cos φ1 × cos φ2 / (πr2 × s1 × s2)
... (1)
Q: Thermal energy
φ1: Angle at which black body A1 receives radiant energy from black body A2
φ2: Angle at which black body A2 receives radiant energy from black body A1
EB1; Radiant energy of black body A1
EB2: Radiant energy of black body A2
r; distance between two black bodies
S1: Area of black body A1
S2: Area of black body A2

  In the above formula (1), the black body A 1 is the heater 26 and the black body A 2 is the reaction tube 23. In FIG. 9, the thermal energy per unit area received by the upper surface member 23 a of the reaction tube 23 from the heater 26 is calculated using the above equation (1), and the thermal energy of the reaction tube 23 having different thermal energy depending on the horizontal distance from the heater 26 is calculated. The thermal energy distribution is shown. As shown in FIG. 9, the thermal energy of the upper surface member 23 a of the reaction tube 23 takes a substantially constant high value in the heater region, which is the upper part of the heater 26, and decreases as the distance from the heater 26 increases.

  FIG. 10 is a view showing a gas flow velocity distribution in the reaction tube 23. As indicated by an arrow 42 in FIG. 10, the gas flow velocity increases near the center of the reaction tube 23 and gradually decreases as it approaches the side wall.

  FIG. 11 is a diagram showing the positional relationship between the heater 26 and the upper surface member 23a of the reaction tube 23 to which the deposit 32 shown in FIG. 4 adheres, and FIG. 12 shows the reaction tube 23 to which the deposit 32 shown in FIG. FIG. 13 is a cross-sectional view taken along the cut line XIII-XIII of the reaction tube 23 to which the deposit 32 shown in FIG. 11 adheres.

  As described above, since the gas phase reaction proceeds from the upstream side to the downstream side in the gas flow direction of the susceptor 25 heated by the heater 26, the deposit 32 is located above the heater 26 of the upper surface member 23 a of the reaction tube 23. It is formed from the vicinity to the downstream side. Further, as shown in FIG. 12, when the surface perpendicular to the gas flow direction is viewed as a cross section, the thickness of the deposit 32 is the smallest near the center of the upper surface member of the reaction tube 23 and increases as the distance from the center increases. Furthermore, as shown in FIG. 13, when the surface parallel to the gas flow direction and perpendicular to the upper surface member and the lower surface member of the reaction tube 23 is viewed as a cross section, the thickness of the deposit 32 is It is small near the upper part and increases as it approaches the gas exhaust port 29 side.

  From the thermal energy distribution received from the heater 26 of the reaction tube 23 shown in FIGS. 9 and 10 and the flow velocity distribution of the gas in the reaction tube 23 and the formation state of the deposit 32 shown in FIGS. It can be seen that the deposits 32 are unlikely to be formed at locations where the wall surface 23 is hot, and the deposits 32 are unlikely to be formed in regions where the gas flow rate is high. As described above, the deposit 32 is a by-product when film formation is performed on the substrate to be processed 24. For example, in the upstream region away from the heater 26 of the reaction tube 23, the transmitted thermal energy is small and gas. Since the temperature condition that can cause the phase reaction is not satisfied, the gas phase reaction itself hardly occurs and the deposit 32 is not easily formed.

  Therefore, the growth rate of the deposit 32 formed on the inner wall of the reaction tube 23 varies depending on the position, and when the film forming process is continued, the thickness of the deposit 32 formed on the inner wall of the reaction tube 23 is uneven. Such unevenness in the thickness of the deposit 32 greatly affects the flow velocity distribution and temperature distribution of the gas in the reaction tube 23 even if it is a minute change, and the uniformity of the thin film formed on the substrate to be processed 24 is lowered. There is a fear.

The infrared reflection means 40 provided in the vapor phase growth apparatus has a high infrared reflectance in the region of the inner wall of the reaction tube 23 where the deposit 32 is likely to adhere, and an infrared reflectance in the region of the inner wall of the reaction tube 23 where the deposit 32 is difficult to adhere. The thickness unevenness of the deposit 32 formed on the inner wall of the reaction tube 23 can be reduced. This also eliminates the disturbance of the gas flow velocity distribution inside the reaction tube 23 and the temperature distribution inside the reaction tube 23, so that film formation on the substrate to be processed 24 can be performed more uniformly.

  The infrared reflecting means 40 is not limited to a configuration in which the infrared reflecting portion 41 having a high infrared reflectivity is disposed as the infrared reflecting means 40 moves away from the heater 26. The arrangement of the infrared reflecting members constituting the infrared reflecting means may be determined according to the gas flow velocity distribution in the reaction tube 23, for example. In such a case, if the infrared reflecting means is arranged with an infrared reflecting member having a low infrared reflectance near the center of the reaction tube 23, and the infrared reflecting member is arranged so as to gradually increase as it approaches the side wall side. Good.

FIG. 14 is a plan view schematically showing the configuration of the infrared reflecting means 50 provided in the vapor phase growth apparatus according to the first embodiment of the present invention, and FIG. 15 is a partial cross-sectional view of the infrared reflecting means 50. The vapor phase growth apparatus of the present embodiment is similar to the above-described vapor phase growth apparatus 20 except that the infrared reflection means 50 is provided in place of the infrared reflection means 22, and thus the overall configuration diagram is omitted and the countermeasure is taken. About the part to attach, the same referential mark is attached | subjected and description is abbreviate | omitted.

  The infrared reflecting means 50 of the present embodiment includes a sheet-like infrared reflecting member 51 provided in contact with the outer wall surface of the reaction tube 23, and the infrared reflecting member 51 is formed with a through hole 52. As the infrared reflecting member 51, for example, a metal thin plate or the like is used in the same manner as the infrared reflecting means 22 of the above-described embodiment.

  Formation of the through hole 52 in the infrared reflecting member 51 is performed by a known processing method such as punching, laser processing, or etching. The shape of the through hole 52 is not limited to a round shape, and may be any shape such as a square shape or a slit shape.

  The infrared reflecting member 51 is not limited to a thin metal plate, and may be a thin film made of a metal material, for example. The through hole 52 is formed in the thin film made of a metal material by, for example, a known processing method such as etching. The through hole 52 may be formed by masking unnecessary portions including the portion where the through hole 52 is to be formed and forming the infrared reflecting member 51.

  According to the infrared reflecting means 50 including the infrared reflecting member 51 in which such a through hole 52 is formed, the area for reflecting the infrared ray 53 can be adjusted by forming the through hole 52. Since the infrared rays 53 can be emitted to the outside of the reaction tube 23, film formation can be performed on the substrate 24 to be processed at a suitable temperature without excessively raising the temperature inside the reaction tube 23.

  Further, the through-hole 52 has a large hole density indicating the area per unit area of the through-hole 52 formed in the infrared reflecting member 51 in the vicinity of the upper portion of the heater 26, and as the heater 26 approaches the gas exhaust port 29 side. It is preferable that the pore density be reduced. By forming the through hole 52 in this way, the infrared reflectance of the region where the amount of the deposit 32 near the heater 26 is small is low, and the infrared reflection of the region where the amount of the deposit 32 on the gas exhaust port 29 side is large. Since the rate can be increased, the thickness unevenness of the deposit 32 can be reduced. In addition, since the disturbance of the gas flow velocity distribution inside the reaction tube 23 can be prevented, film formation on the substrate to be processed 24 can be performed more uniformly.

FIG. 3 is a cross-sectional view seen from the side showing the configuration around the reaction furnace 21 of the vapor phase growth apparatus 20 in a simplified manner. It is a top view of the reaction tube 23 in which the infrared reflection means 22 is provided. It is a figure which shows the relationship between the frequency | count of a film-forming process, and the area of the adhesion area | region of a deposit. It is sectional drawing of the reaction tube 23 which performed the film-forming process using the vapor phase growth apparatus which is the same structure as the vapor phase growth apparatus 20 except not providing the infrared reflection means 22, and made the deposit 32 adhere. FIG. 5 is a view of an upper surface member 23a of the reaction tube 23 shown in FIG. 4 as viewed from the susceptor 25 side. When using a horizontal MOCVD apparatus 1 having no infrared reflective means shown in vapor phase growth apparatus 20 and 16 Ru provided an infrared reflecting means 22, the time required to reach a temperature at which the temperature of the target near the substrate is predetermined It is a figure which shows the result of having measured, respectively. FIG. 2 is a diagram showing the relationship between the number of processes, which is the number of times a substrate to be processed is processed by the vapor phase growth apparatus 20 shown in FIG. It is a top view which shows roughly the structure of the infrared reflective means 40 with which a vapor phase growth apparatus is equipped. FIG. 3 is a diagram showing a reaction tube 23 and a thermal energy distribution received from a heater 26 of an upper surface member 23a of the reaction tube 23 when a surface perpendicular to the gas flow direction is viewed as a cross section. FIG. 4 is a view showing a gas flow velocity distribution in a reaction tube 23. FIG. 5 is a diagram showing a positional relationship between an upper surface member 23a of the reaction tube 23 to which the deposit 32 shown in FIG. It is sectional drawing seen from the cut surface line XII-XII of the reaction tube 23 to which the deposit | attachment 32 shown in FIG. 11 adheres. It is sectional drawing seen from the cut surface line XIII-XIII of the reaction tube 23 to which the deposit | attachment 32 shown in FIG. 11 adheres. It is a top view which shows roughly the structure of the infrared reflection means 50 with which the vapor phase growth apparatus which is 1st Embodiment of this invention is equipped. 3 is a partial cross-sectional view of infrared reflecting means 50. FIG. It is a schematic diagram explaining the structure around the reaction furnace 2 of the conventional typical horizontal type | mold MOCVD apparatus 1. FIG. FIG. 3 is a schematic diagram showing a state in which a by-product 11 adheres to the inner wall of a reaction tube 3 in a film forming step. It is a figure which shows the relationship between the process frequency which is the frequency | count which processes the one to-be-processed substrate by the horizontal type MOCVD apparatus shown in FIG. 16, and the thickness of a deposit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Vapor growth apparatus 21 Reactor 22, 40, 50 Infrared reflecting means 23 Reaction tube 24 Substrate 25 Susceptor 26 Heater 27 Gas inlet 28 Gas inlet 29 Gas exhaust 30 Gas exhaust 31 Opening 32 Deposit 41a , 41b, 41c, 41d, 41e, 41f Infrared reflecting portion 42 Gas flow velocity 51 Infrared reflecting member 52 Through hole 53 Infrared ray

Claims (5)

Introducing a gas containing a film forming raw material component into a reaction tube in which the substrate to be processed is accommodated in a direction along the surface of the substrate to be processed which is to be formed, and heating the introduced gas by a heating means; in the vapor phase growth apparatus for growing on a substrate to be processed to film-forming ingredients while the reaction by,
Infrared reflecting means provided so as to be in contact with the outer wall surface of the reaction tube, reflecting infrared rays, and changing the infrared reflectance within the surface in contact with the outer wall surface of the reaction tube ,
It said infrared reflecting means, the reaction tube outer wall surface provided in contact, vapor deposition apparatus characterized by including Mukoto a sheet of infrared reflecting member through-hole is formed. Infrared reflecting means
2. The vapor phase growth apparatus according to claim 1, wherein the vapor deposition apparatus is provided so as to be in contact with an outer wall surface of the reaction tube over an adhesion region of an adhesion material adhering to the inner wall of the reaction tube. Infrared reflecting means
3. The vapor phase growth apparatus according to claim 1, wherein the infrared reflectance changes so that the infrared reflectance increases as the distance from the heating means increases. Infrared reflecting means for reflecting infrared rays is provided on the outer wall surface of the reaction tube in which the substrate to be processed is accommodated , and the infrared reflectance changes within the surface on the side in contact with the outer wall surface of the reaction tube. Providing an infrared reflecting means including a sheet-like infrared reflecting member on which is formed ;
A gas introduction step for introducing a gas containing a film forming raw material component into the reaction tube so as to flow in a direction along the surface of the substrate to be formed;
And a film forming step of growing a film forming raw material component on a substrate to be processed while reacting by introducing a gas to be introduced. In the step of providing infrared reflecting means on the outer wall surface of the reaction tube,
Infrared reflecting means
5. The vapor phase growth method according to claim 4 , wherein the vapor deposition method is provided over an adhesion region of an adhering substance adhering to the inner wall of the reaction tube.

Images