JP4873169B2 - Filling method of solid organometallic compound - Google Patents

Description

  The present invention relates to a method of filling a solid organometallic compound for epitaxial vapor deposition by MOCVD (Metalorganic Chemical Vapor Deposition) for producing a compound semiconductor.

  Group III-V compound semiconductors have excellent characteristics advantageous for high-speed devices and light-emitting devices. Utilizing these excellent properties, various devices such as high electron mobility transistors, light emitting diodes and semiconductor lasers have been realized.

  Crystal growth of these compound semiconductors is manufactured by MOCVD using an organometallic compound or the like. The MOCVD method is one of crystal growth methods often used for forming an epitaxial thin film of a compound or a mixed crystal semiconductor. For example, organometallic compounds such as trimethylindium, trimethylaluminum, trimethylgallium, and dimethylzinc, and alkylphosphine are used. In this method, an organic group V compound such as alkylarsine is vaporized and a thin film crystal is grown by utilizing a thermal decomposition reaction on a substrate.

  These organometallic compounds used in the MOCVD method are usually filled in a sealed container to which gas introduction and discharge pipes are connected, the container temperature is kept constant by a thermostatic bath, etc., and a carrier gas such as hydrogen is introduced into the container. The carrier gas saturated with the vapor of the organometallic compound is obtained from the exhaust pipe.

  In general, the organometallic compound that is solid at room temperature is attached to the inner wall of the container or filled in a granular form. However, the solid organometallic compound filled by these filling methods has a drawback that it is difficult to constantly supply a constant concentration with a carrier gas. That is, it is difficult to keep the contact state between the carrier gas and the solid organometallic compound uniform, and the contact area varies, so that it cannot be supplied at a constant concentration.

  A compound semiconductor formed by epitaxially growing an organometallic compound has a significant adverse effect on electrical and optical characteristics when the composition ratio of the organometallic compound during growth changes. Therefore, in order to obtain a high-performance element, it is necessary to stably supply a certain concentration of organometallic compound. Further, at that time, it is required to be realized only by a vaporization container without requiring a complicated supply device. In particular, for solid organometallic compounds such as trimethylindium, when the carrier gas is bubbled in the same container as the liquid organometallic compound, the supply amount varies depending on whether the filling amount of the organometallic compound is large or small. For this reason, there is a problem that it is difficult to use the filled organometallic compound to the end under certain conditions.

  As a method for solving these problems, as shown in FIG. 1, an organometallic compound that is solid at room temperature and a stainless steel filling are placed in a container, and once heated to a melting point or higher, the organometallic compound is melted. By cooling while rotating the container, the solid organometallic compound can be uniformly dispersed in the container, and even when the carrier gas is supplied by a bubbling method, good supply stability can be maintained (Japanese Patent Laid-Open No. 8- No. 299778 is known: Patent Document 1). However, there is a problem in the method in which the solid organometallic compound is once melted to a melting point or higher and cooled while rotating the container. When the organometallic compound is melted and cooled and solidified while rotating the container, a part of the organometallic compound is divided into a valve (6, 7) at the upper part of the container body 1 and a pipe (2 at the lower part of the valve). 3), and in some cases, it may become clogged. If the carrier gas is supplied in such a state in a bubbling system, the piping in the valve or directly under the valve does not enter the constant temperature bath that is normally used to keep the container at a constant temperature. Cannot be supplied at a stable concentration for at least an initial hour until the solid organometallic compound in the valve or in the pipe under the valve is no longer vaporized, and cannot be introduced into the epitaxial vapor phase growth apparatus. So there was a drawback that it had to be discarded.

JP-A-8-299778

  The present invention has been made in view of the above circumstances, and can supply a solid organometallic compound to be supplied in a solid organometallic compound manufacturing apparatus for epitaxial vapor phase growth at a stable concentration from the initial stage of use. It aims at providing the filling method of a solid organometallic compound.

  As a result of intensive studies to achieve the above object, the inventors of the present invention heated the valve and the piping portion while pulling down the outlet piping at the top of the solid organometallic compound container and adhered to these portions. By removing the solid organometallic compound, it was found that the solid organometallic compound in the container can be supplied at a stable concentration from the initial stage of the start of use, and the present invention has been made.

Accordingly, the present invention provides the following solid organometallic compound filling method.
Claim 1:
Each one location or more carrier gas inlet and a gas mixture discharge pipe possess respectively the top, and supplies the solid organometallic compound to the inlet pipe and respectively the discharge tube container valve is being interposed, this In the method of heating and melting the solid organometallic compound above its melting point, and then cooling and filling the solid organometallic compound into the container, while pulling the outlet pipe at the top of the container of the obtained solid organometallic compound to a reduced pressure, Close the valve interposed in the introduction pipe, open the valve interposed in the discharge pipe, and heat the introduction pipe and the discharge pipe and each valve interposed in these pipes to introduce the introduction A solid organometallic compound filling method comprising removing a solid organometallic compound adhering to each valve portion interposed between a pipe and a discharge pipe and these pipes from the discharge pipe.
Claim 2:
2. The solid organometallic compound filling method according to claim 1, wherein the solid organometallic compound is trimethylindium.
Claim 3:
3. The method of filling a solid organometallic compound according to claim 1, wherein the carrier gas introduction pipe is opened at the upper part in the container and the mixed gas discharge pipe is opened at the lower part in the container.

  According to the solid organometallic compound filling method of the present invention, since the solid organometallic compound filled in the container can be supplied at a stable concentration from the initial stage of the start of use, it can be used immediately as a raw material for vapor phase growth. it can.

  The container used for filling the solid organometallic compound of the present invention has one or more carrier gas inlet and outlet pipes at the top, respectively, and the container is filled with a stainless steel filler and has a porosity of Adjust to 50-80% by volume. The container is further supplied with a solid organometallic compound at room temperature, heated to a melting point or higher of the solid organometallic compound, melted, and then cooled while rotating to fill the container with the solid organometallic compound. At this time, while pulling the outlet pipe at the top of the container to a reduced pressure, the valve and the pipe part are heated to remove the solid organometallic compound adhering to the upper valve and the pipe part, thereby removing the solid organometallic compound for vapor phase growth. Fills the vaporization container.

  In FIG. 1, an example of the container used for the filling method of the solid organometallic compound of this invention is shown. In this container, a carrier gas introduction pipe 2 and a mixed gas discharge pipe 3 are opened in the container 1, respectively, the carrier gas introduction pipe 2 is opened at the top, and the mixed gas discharge pipe 3 is opened at the bottom. The carrier gas introduction pipe 2 may be open at the bottom and the mixed gas discharge pipe 3 may be opened at the top, but preferably the carrier gas introduction pipe 2 is discharged so that the solid organometallic compound having a high gas specific gravity is discharged at a higher concentration. It is preferable that the mixed gas discharge pipe 3 is opened at the upper part. Reference numerals 5, 8, and 9 are nozzles.

  The size of the entire container is not particularly limited, but a container usually used in this field preferably has a diameter of 30 to 500 mmφ and a height of 50 to 500 mm.

  The vaporizing container 1 is filled with the filling 4 from the nozzle 5. As the filling, a stainless steel filling is good in heat conduction, and when used in a thermostatic bath, external heat is put inside the container. It is preferable because it is easy to convey.

  Next, the solid organometallic compound used here can be used as long as it is solid at room temperature, and examples thereof include trimethylindium and cyclopentadienylmagnesium. This is particularly effective for trimethylindium which is generally used in a large amount for vapor phase growth.

  The method for filling the vaporization container with the solid organometallic compound is not particularly limited, and sublimation filling under reduced pressure or open filling from the nozzle 5 under an inert gas atmosphere such as nitrogen may be used.

  The solid organometallic compound vaporization vessel is heated as it is to the melting point of the solid organometallic compound or more to melt, but the heating method is not particularly limited and may be heated using an oil bath, a thermostatic bath, etc. In the case of trimethylindium, the temperature may be about 90 to 110 ° C., which is higher than the melting point. After reaching a predetermined temperature, the vaporization container is cooled while being rotated, whereby a state in which the organometallic compound is uniformly dispersed and solidified in the container is obtained. This rotation cooling method may be natural cooling using, for example, a pot mill turntable.

  In this state, the solid organometallic compound adheres to the upper part of the vaporization container, the carrier gas introduction pipe 2, the discharge pipe 3, the valve 6 and the valve 7, and in particular, the solid organometallic compound attached to the discharge pipe 3 and the valve 7. Since it cannot be put in a thermostatic bath at the time of epitaxial growth, it is affected by the outside air temperature and is subject to supply stability. Conventionally, as a method for solving this problem, after cooling the container while rotating, it has been attempted to heat the piping in the valve or directly under the valve to remelt the attached organometallic compound and drop it under its own weight. However, this method has a drawback that not only a considerable removal time is required but also the organometallic compound cannot be completely removed.

  Therefore, in the present invention, in order to remove the attached solid organometallic compound, for example, an apparatus shown in FIG. 2 was used. This apparatus is attached to equipment equipped with a vacuum pump, and while reducing the pressure with the vacuum pump, the carrier gas introduction pipe 2, the discharge pipe 3, the valve 6 and the valve 7 are heated, and the solid organic metal adhering to the pipe It removes compounds.

  More specifically, in FIG. 2, 10 vacuum pumps are operated from a state in which all the valves are closed, the valve 13 is opened, and it is confirmed that the pressure gauge 17 indicates depressurization. The degree of reduced pressure is not particularly limited, but is preferably 4000 Pa or less because the treatment takes time when the pressure is high.

  Next, the valve 7 is opened, and the valve 6, the carrier gas introduction pipe 2, the discharge pipe 3, and the valve 7 excluding the container body 1 are heated to remove the organometallic compound adhering and remaining inside. For the heating of the valve 6 or the like, a known method such as a method of heating with hot air such as a warm air heater (dryer), a method of directly heating by winding a tape heater or the like can be adopted, and the temperature is What is necessary is just to be 40 degreeC or more. In particular, since the discharge pipe 3 and the valve 7 have a direct influence when used for vapor phase growth, the treatment is indispensable. At that time, for the purpose of suppressing sublimation of the organometallic compound inside the container body 1, the container body 1 may be cooled with a thermostatic bath, dry ice, or the like.

  The heating time is preferably 30 minutes or less, although it depends on the degree of pressure reduction and the heating temperature. After the treatment, the valve 7 is closed, the atmospheric gas is introduced from the valve 11, the valve 6 is closed, and the container is removed.

  When all the valves are closed without using 10 vacuum pumps, the valves 11, 6, 7, 14 are opened, and the valves 6, 7 and the pipes 2, 3 are heated while the gas is flowing from the gas cylinder 15. However, a processing method is also possible, but since processing time is required, processing under reduced pressure is preferable. Reference numeral 16 denotes a pressure regulator.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

[Example 1]
A 100 mesh stainless steel wire mesh is cut into 3 mm × 15 mm and then rounded to a diameter of about 3 mmφ. 100 g of a product crushed in the radial direction so that the porosity was about 70% by volume was prepared. The volume of the stainless steel packing was about 150 ml.
As shown in FIG. 1, the vaporization container 1 having an outer diameter of 60.5 mmφ and a body height of 115 mm and an internal volume of 200 ml is sufficiently washed with water and dried. After filling and the nozzle 5 was closed, a vacuum pump was connected to the nozzle 9 and evacuated to 10 Pa. Thereafter, helium gas was introduced from the nozzle 8 to perform gas replacement. After repeating this operation three times, the nozzle 8 and a container (not shown) containing trimethylindium were connected, the valve 6 was opened, and the vaporization container 1 was transferred and filled using sublimation. The filling amount was 105 g.
Thereafter, the vaporization container 1 was immersed in an oil bath, heated to 100 ° C. and held for 0.5 hour, and then the vaporization container 1 was taken out and fixed in a cylindrical container (not shown). This was placed on a pot mill turntable (not shown) and cooled while the filling container 1 was rotated at 60 rpm for 3 hours.
Then, the vaporization container 1 was taken out and the vaporization container 1 was connected to the processing apparatus shown in FIG. 10 vacuum pump is operated, valve 13 is opened, 17 pressure gauge is confirmed to be 4000 Pa or less, valve 7 is opened, valve 6 with carrier air (dryer), carrier gas introduction pipe 2, discharge Tube 3 and valve 7 were heated for 10 minutes. The temperature of the piping at that time was about 50 ° C.
Next, a test was conducted to see if the organometallic compound could be stably supplied from this vaporization vessel. That is, the vaporization vessel 1 containing trimethylindium is mounted in a thermostat (not shown) adjusted to 20 ° C., and high purity helium is vented to the vessel through the carrier gas introduction pipe 2 at a rate of 500 ml / min. The gas phase of trimethylindium obtained from the discharge pipe 3 was measured with a gas concentration meter (manufactured by Aopriori, not shown).
FIG. 3 shows the relationship between feed time (elapsed time immediately after the start of feed) and the concentration of trimethylindium. As shown in FIG. 3, according to the present invention, it was confirmed that the concentration was stably obtained immediately after the start of feeding and can be used immediately as a raw material for vapor phase growth.

[Example 2]
As a result of processing and testing in the same manner as in Example 1 except that a tape heater was wound instead of using a warm air heater (dryer) and heating was performed at about 60 ° C. for 15 minutes, the results shown in FIG. In the same manner as in Example 1, it was confirmed that the concentration was obtained stably immediately after the start of feeding, and it could be used immediately as a raw material for vapor phase growth.

[Comparative Example 1]
The treatment was performed in the same manner as in Example 1 except that the pressure was reduced by a vacuum pump and the piping was not heated. As a result, as shown in Comparative Example 1 in FIG. 3, it was confirmed that one hour or more passed until the concentration was stabilized, and it was unstable thereafter.

[Comparative Example 2]
Without using a vacuum pump, with all the valves closed, the valves 11, 6, 7, and 14 are opened, and helium gas is allowed to flow at 100 ml / min. 7 and pipes 2 and 3 were treated in the same manner as in Example 1 except that the treatment was performed for 20 minutes. As a result, as in Comparative Example 1 in FIG. 3, it was confirmed that one hour or more passed until the concentration was stabilized, and it was unstable thereafter.

It is a schematic explanatory drawing which shows an example of the vaporization container used for the filling method of the solid organometallic compound of this invention. It is a schematic explanatory drawing which shows an example of the apparatus used for the filling method of the solid organometallic compound of this invention. It is a graph which shows the relationship between feed time and the density | concentration of trimethylindium.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vaporization container 2 Carrier gas introduction pipe 3 Discharge pipe 4 Filling 5 Nozzle 6 Valve 7 Valve 8 Nozzle 9 Nozzle 10 Vacuum pump 11 Valve 12 Valve 13 Valve 14 Valve 15 Gas cylinder 16 Pressure regulator 17 Pressure gauge

Claims (3)

Each one location or more carrier gas inlet and a gas mixture discharge pipe possess respectively the top, and supplies the solid organometallic compound to the inlet pipe and respectively the discharge tube container valve is being interposed, this In the method of heating and melting the solid organometallic compound above its melting point, and then cooling and filling the solid organometallic compound into the container, while pulling the outlet pipe at the top of the container of the obtained solid organometallic compound to a reduced pressure, Close the valve interposed in the introduction pipe, open the valve interposed in the discharge pipe, and heat the introduction pipe and the discharge pipe and each valve interposed in these pipes to introduce the introduction A solid organometallic compound filling method comprising removing a solid organometallic compound adhering to each valve portion interposed between a pipe and a discharge pipe and these pipes from the discharge pipe.   2. The solid organometallic compound filling method according to claim 1, wherein the solid organometallic compound is trimethylindium. 3. The method of filling a solid organometallic compound according to claim 1, wherein the carrier gas introduction pipe is opened at the upper part in the container and the mixed gas discharge pipe is opened at the lower part in the container.

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