JP4144259B2 - Semiconductor heat treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention controls the electrical characteristics of a heat treatment apparatus suitable for heat treatment that requires vapor pressure control with a metal or the like, in particular, a III-V group semiconductor semiconductor such as GaAs, GaP, InP or a II-VI group compound semiconductor single crystal such as ZnSe. The present invention relates to a semiconductor heat treatment apparatus.
[0002]
[Prior art]
Usually, in heat treatment of metals, heat treatment in the atmosphere in a BOX furnace or the like is generally performed in a state where an inert gas is filled in a vessel with a pressure vessel or the like, and vapor pressure control is possible. There are few unprecedented heat treatment furnaces.
[0003]
Also, some alloys such as compound semiconductors dissociate from the metal surface when heated, so there are metals that require vapor pressure control to maintain product characteristics. As a heat treatment method for these metals, a general method is to put a metal and a metal for vapor pressure compensation into a quartz ampoule or the like and seal it in a vacuum, and put the ampoule into a heat treatment furnace for heat treatment.
[0004]
With regard to materials such as compound semiconductors whose dissociation from the surface becomes a problem due to the heat treatment temperature, the temperature is raised to a predetermined heat treatment temperature in a conventional BOX furnace or a general pressure vessel type heat treatment furnace. Dissociation from the metal surface occurs, affecting the product characteristics. Further, there is a problem that a sufficient heat treatment effect cannot be obtained by lowering the heat treatment temperature in order to avoid dissociation.
[0005]
Further, in the method of performing heat treatment by vacuum-sealing on a quartz ampule, a process of sealing on the quartz ampule occurs, so that the cost of the quartz ampule, the equipment used for sealing, and the cost of these operations are generated. There is a problem in cost. Further, if the weight of the metal to be processed exceeds 10 kg due to the strength problem of quartz, it is very difficult to process with this method.
[0006]
In detail, as a method for growing a compound semiconductor single crystal, liquid sealing Czochralski method (LEC method), slow cooling method (GF), horizontal Bridgman method (HB method), vertical Bridgman method (VB method), etc. Several proposals have been made, but since it is inevitable that the characteristics in the crystal will be non-uniform, after the growth, the crystal is cut into a block or wafer that is ingot or cylindrically ground using a heat treatment device. Then, heat treatment is performed to improve and homogenize the crystal characteristics.
[0007]
However, in the conventional heat treatment equipment, the heat treatment object is placed in a quartz ampoule and vacuum sealed, and then the heat treatment is performed. Therefore, if the heat treatment object becomes larger as the diameter of the single crystal becomes larger, the quartz ampule becomes larger. Therefore, there is a problem that the sealing operation becomes difficult and the quartz ampule is destroyed after the heat treatment to take out the heat-treated material, so that the economy is low and the cost is high.
[0008]
Therefore, in the past, a structure of a heat-resistant container that can be opened and closed so that a single crystal to be processed of a semiconductor can be accommodated, and further, a structure in which the heat-resistant container is housed in a pressure container in order to improve pressure resistance performance, that is, a high-pressure furnace. It has been proposed to use a vapor pressure control mechanism having a structure in which an inner chamber is further provided (Japanese Patent Laid-Open No. 11-310499).
[0009]
[Problems to be solved by the invention]
However, the above publication only shows the concept of a heat-resistant container that is divided into two openable and closable via a seal portion, and does not disclose any specific means for opening and closing the heat-resistant container. Therefore, it is desirable to provide a heat treatment apparatus that can safely and easily take in and out the heat-treated material, is easy to operate, and is highly practical.
[0010]
In addition, when the heat-resistant container has a two-part structure that can be opened and closed through a seal portion, it is difficult to reliably perform sealing at the lower portion of the inner chamber, which is the open / close portion, at a high temperature. In particular, a more complete seal structure is required for application to a system using a high vapor pressure component such as As or P, which has toxicity or may ignite.
[0011]
Accordingly, the object of the present invention is to solve the above-mentioned problems of the prior art, a semiconductor heat treatment apparatus that is easy to put in and out of the heat-treated material and is highly practical, and further a semiconductor heat treatment with a more complete heat-resistant container seal. To provide an apparatus.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is configured as follows.
[0013]
According to the first aspect of the present invention, there is provided a gas impermeable heat-resistant container which is provided with a heater chamber in which a heater is installed in a pressure vessel, and which can be opened and closed so that a semiconductor single crystal to be processed can be accommodated in the heater chamber. In the semiconductor heat treatment apparatus provided with the inner chamber , the heat-resistant container is divided into two parts, a lower container part and an upper container part that are in contact with each other via a sealing material, and at least of the lower container part and the upper container part One is attached to a support shaft that can be moved up and down, whereby the lower container part and the upper container part are separated from and in contact with each other, and the heat-resistant container can be opened and closed via a sealing material.
[0014]
According to this feature, has a heater chamber into the pressure vessel, further in the semiconductor heat treatment apparatus having an inner chamber in the heater chamber, the inner chamber easily made of heat-resistant container can be opened and closed through a sealing material, practical A typical heat treatment apparatus can be constructed, and no sealing work with a quartz ampule or the like is required. In addition, the pressure inside and outside the heat-resistant container is equal to the pressure inside the pressure container and does not cause a differential pressure. Therefore, a structure having a heater chamber and an inner chamber inside the pressure container is used. By filling this gas, the differential pressure inside and outside the inner chamber can be eliminated, and the release of gas from the inside of the inner chamber to the outside can be suppressed.
[0015]
More specifically, according to the first aspect of the present invention, a heater chamber in which a heater is installed is provided in a pressure vessel, and the opening and closing of the single crystal made of a compound semiconductor can be accommodated in the heater chamber. has a structure in which a heat-resistant container that can advance to encapsulate high dissociation pressure component of elements constituting the compound semiconductor in the heat-resistant container, a gas atmosphere of high elemental vapor pressure of the constituent elements of the single crystal In the semiconductor heat treatment apparatus for performing heat treatment of the single crystal below, the heat-resistant container has a structure that can be divided into a lower container part and an upper container part via a sealing material, and the lower container part and the upper container It includes a configuration in which the portion is attached to the lower support shaft and the upper support shaft so that they can be brought into contact with and separated from each other.
[0016]
According to a second aspect of the present invention, there is provided the semiconductor heat treatment apparatus according to the first aspect, wherein the lower container portion is configured as a sample stage, and the upper container portion is hermetically covered with the sample stage via the sealing material. A structure that can be mechanically applied externally to the joint between the sample stage and the upper container by being configured as a container having an open port, and being installed in a drive mechanism that allows the support shaft to be moved vertically. It is characterized by that.
[0017]
According to this feature, it is possible to realize a structure in which mechanical pressure is applied to the lower and upper container parts constituting the heat-resistant container that can be opened and closed from the outside in the vertical direction in which both are in contact with each other. It becomes possible to further improve the sealing effect at the seal part between the lower container part and the upper container part. In the unlikely event that the gas pressure inside the heat-resistant container becomes higher than the gas pressure outside the heat-resistant container, it is possible to avoid a situation in which the internal vapor pressure cannot be controlled because the heat-resistant container opens.
[0018]
According to a third aspect of the present invention, in the semiconductor heat treatment apparatus according to the second aspect, the lower container part and the upper container part are each attached to a support shaft that can be moved up and down independently, and the upper container part has a periphery near its top. A flange is provided on the top surface of the cylindrical support member that is erected so as to surround the heating element in the pressure vessel. A semiconductor heat treatment apparatus characterized in that an inner chamber can be formed by contacting a side container portion.
[0019]
According to this feature, the upper container portion can be placed on the top surface of the cylindrical support member standing in the pressure vessel and positioned in the pressure vessel, and the upper vessel positioned in the pressure vessel can be positioned. The inner chamber can be formed by bringing the sample stage of the lower container part into contact with the lower opening of the part, and this can be kept airtight.
[0020]
A fourth aspect of the present invention is the semiconductor heat treatment apparatus according to any one of the first to third aspects, wherein the gas-impermeable heat-resistant container is made of graphite having a surface coated with CVD, a metal material, and ceramics. material, characterized by using special carbon material, or a glass material having airtightness.
[0021]
As described above, by using a dense material having a very low gas permeability as the material of the heat-resistant container constituting the inner chamber, it is possible to suppress the release of gas that permeates from the heat-resistant container. This also results in increasing the vapor pressure retention efficiency in the inner chamber.
[0022]
According to a fifth aspect of the present invention, in the semiconductor heat treatment apparatus according to any one of the first to fourth aspects, the foil is used as a material for the sealing material that holds the open / close portion of the gas-impermeable heat-resistant container in an airtight manner. Features.
[0023]
In the processing apparatus according to the present invention, since it is necessary to put a metal to be processed into the inner chamber, the inner chamber has an opening / closing part due to its structure. It is from this opening / closing part that the vapor pressure from the inner chamber is most likely to leak, and for the purpose of suppressing the leakage from here, a graphite foil (cleavable graphite) is used as a sealing material for the opening. Using this graphoil makes it possible to suppress leakage from the inner chamber easily and effectively.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the illustrated embodiments.
[0025]
FIG. 1 shows an example applied to a heat treatment apparatus for GaAs single crystal. The semiconductor heat treatment apparatus, the provided heater chamber 30 having a heater 5 is a heating element into the pressure vessel 1, and further a inner chamber 20 provided a structure consisting of a gas-impermeable heat-resistant container 21 in the heater chamber . The heat-resistant container 21 has a structure that can be opened and closed so that the GaAs ingot 2 that is a single crystal to be processed of the compound semiconductor can be accommodated, and the element 3 (high dissociation pressure component element constituting the compound semiconductor in the heat-resistant container 21 ( Here, As) is sealed in advance, and the ingot 2 can be heat-treated in a gas atmosphere of an element having a high vapor pressure among the constituent elements of the GaAs ingot 2.
[0026]
The heat-resistant container 21 is divided into a lower container part 4 (lower inner chamber part) and an upper container part 7 (upper inner chamber part) that are in contact with each other via a sealing material 9, and the lower container part. At least one of the 4 and the upper container part 7 is attached to a support shaft that can move up and down, and is configured to be able to contact and separate from each other. Here, the lower container part 4 and the upper container part 7 are attached to the lower support shaft 6 and the upper support shaft 8, respectively, whereby the lower container part 4 and the upper container part 7 are separated from and in contact with each other. It is comprised so that a container can be opened and closed via a sealing material.
[0027]
In the case of the present embodiment, the lower container part 4 is configured as a sample stage, and the upper container part 7 is configured as a container having a lower opening that is airtightly covered on the sample stage via the sealing material 9. The lower support shaft 6 and the upper support shaft 8 are mounted on a drive mechanism (not shown) that drives the lower support shaft 6 and the upper support shaft 8 so as to be movable in the vertical direction. Thereby, it has a structure in which pressure can be mechanically applied to the joint portion between the lower container portion 4 and the upper container portion 7 from the outside.
[0028]
The upper container part 7 is provided with a flange part 7b around the top part 7a, and the flange part 7b surrounds the heater 5 in the pressure vessel 1 and is a top surface of a cylindrical support member 10 that stands upright. Thus, the upper container portion 7 is positioned in the pressure vessel 1, and the heater chamber 30 is formed by the top portion 7 a and the flange portion 7 b and the cylindrical support member 10. Yes. In the heater chamber 30, the inner chamber 20 can be formed by bringing the sample stage as the lower container part 4 into contact with the lower opening of the upper container part 7.
[0029]
The gas-impermeable heat-resistant container 21 forming the inner chamber 20 is made of graphite having a CVD coating on its surface to prevent gas permeation. However, it can also be made of a dense material with extremely low gas permeability, such as quartz glass, alumina, silicon carbide, silicon nitride, glassy carbon, or molybdenum.
[0030]
The foil 9 (cleavable graphite) is used for the sealing material 9 that hermetically holds the open / close portion of the gas-impermeable heat-resistant container 21 (inner chamber 20).
[0031]
According to the above heat treatment apparatus, since the heat-resistant container 21 has a structure that can be easily opened and closed via the sealing material 9, a practical heat treatment apparatus that can be easily handled can be configured. No sealing work with quartz ampules is required.
[0032]
Also, having a heater chamber 30 into the pressure vessel 1, further has a structure having an inner chamber 20 into the heater chamber 30, and out of the pressure of the heat-resistant container 21 is equal to the pressure in the pressure vessel 1, the pressure difference For example, by filling the outside of the inner chamber 20 with a gas such as an inert gas, the pressure difference between the inside and outside of the inner chamber 20 can be eliminated. Can be suppressed.
[0033]
Moreover, since the lower container part 4 and the upper container part 7 which comprise the inner chamber 20 are attached to the lower support shaft 6 and the upper support shaft 8 which can be moved up and down by a drive mechanism, the lower container part 4 and the upper container part A pressure can be mechanically applied to the container part 7 from the outside in the up-down direction where both are in contact with each other. Accordingly, it is possible to further improve the confidentiality retaining action of the seal material 9 between the lower container part 4 and the upper container part 7, which is performed by the seal material 9 made of graphoyl. Even if the gas pressure inside the heat-resistant container 21 becomes higher than the gas pressure outside the heat-resistant container 21, either the lower container part 4 or the upper container part 7 of the heat-resistant container 21 is displaced and opened. It is possible to avoid a situation in which internal vapor pressure control cannot be performed.
[0034]
Next, an actual heat treatment example will be described.
[0035]
In order to confirm the effect of the present invention, an experiment was conducted using GaAs known as a compound semiconductor material as an example of heat treatment. GaAs is generally heat-treated to improve its product characteristics. In addition, as GaAs dissociates As from the surface when heated, it is necessary to perform the heat treatment while maintaining the As gas pressure.
[0036]
First, the structure of the heat treatment apparatus used in the experiment will be described. As shown in FIG. 1, a heat-resistant container 21 (inner chamber 20) composed of an upper container part 7 (upper inner chamber part) and a lower container part 4 (lower inner chamber part) is arranged inside the pressure vessel 1. The lower container portion 4 was attached in a state of being placed on the lower support shaft 6 penetrating into the pressure vessel 1 from the bottom of the pressure vessel 1. The lower support shaft 6 has a structure that can be driven up and down. The upper container part 7 is arranged in a state where the flange part 7 b is placed on the support member 10. An upper support shaft 8 penetrating from above into the pressure vessel 1 is attached to the upper portion of the upper vessel portion 7. Similar to the lower support shaft 6, the upper support shaft 8 has a vertical drive function. By driving the upper support shaft 8 and the lower support shaft 6, the upper container portion 7 and the lower container portion 4 can be sealed and opened. In addition, a graphic foil is provided as a sealing material 9 at a contact portion between the upper container portion 7 and the lower container portion 4. Moreover, the heater 5 is installed in the outer peripheral part of the inner chamber 20, and it heats with this heater.
[0037]
Further, the pressure vessel 1 is provided with a vacuum exhaust device and an inert gas introduction pipe so that the pressure vessel 1 can be evacuated and purged.
[0038]
In the prototype experiment, graphite having a CVD coating on its surface was used as a material for the heat-resistant container 21 in order to suppress gas permeation. Moreover, a resistance heater made of graphite was used as the heater.
[0039]
In the trial production, a 20 kg GaAs ingot 2 was used, and a heat treatment experiment of 20 hours at an ultimate temperature of 1100 ° C. was performed 30 times.
[0040]
In the experiment, first, the GaAs ingot 2 was set in the lower container portion 4, and at the same time, As corresponding to the As dissociation pressure of GaAs at 1100 ° C. was set as the element 3. After setting, the inside of the pressure vessel 1 was evacuated by a vacuum pump with the inner chamber 20 opened as shown in FIG. 1, and then filled with 1.0 kg / cm ^{2 of} inert gas. After filling with the inert gas, the upper support shaft 8 and the lower support shaft 6 were driven to close the inner chamber 20, and further, sealing was performed by applying a load of about 5.0 kg / cm ² from above and below. Thereafter, the heater 5 was energized, the temperature was raised to 1100 ° C., and heat treatment was performed for 20 hours.
[0041]
As a result, in all 30 experiments, there was no gas leakage from the inner chamber 20, and no trace of As dissociated from the surface of the GaAs ingot 2 was observed, and the vapor pressure control was performed reliably. I was able to prove.
[0042]
【The invention's effect】
As described above, according to the present invention, the following excellent effects can be obtained.
[0043]
According to the heat treatment apparatus of the present invention, since the lower container part and the upper container part constituting the inner chamber are attached to the lower support shaft and the upper support shaft that can be moved in the vertical direction, the heat-resistant container is interposed via the sealing material. A practical heat treatment apparatus that can be easily opened and closed and is easy to handle in heat treatment of semiconductors that require vapor pressure control can be achieved at low cost and easily.
[0044]
In addition, it has a structure having a heater chamber in the pressure vessel and an inner chamber in the heater chamber, and the pressure inside and outside the heat-resistant vessel is equal to the pressure inside the pressure vessel, so there is no difference in pressure. For example, by filling the inside of the inner chamber with a gas such as an inert gas, the pressure difference between the inside and outside of the inner chamber can be eliminated, and the release of gas from the inside of the inner chamber to the outside can be suppressed.
[0045]
Further, since the sealing material is made of graphoyl, the sealing action can be performed more effectively. Furthermore, since the pressure can be mechanically applied from the outside in the vertical direction in which both the lower container part and the upper container part are in contact with each other, the lower container part and the upper container are operated by a sealing material made of a graphoil. It is possible to further improve the confidentiality keeping action of the seal material between the parts.
[Brief description of the drawings]
FIG. 1 is a schematic view of a semiconductor heat treatment apparatus of the present invention.
[Explanation of symbols]
1 Pressure Vessel 2 GaAs Ingot (Semiconductor Processing Single Crystal)
3 Elements (As)
4 Lower container (lower inner chamber)
5 Heater (heating element)
6 Lower support shaft 7 Upper container part (upper inner chamber part)
8 Upper support shaft 9 Sealing material (Graph foil)
10 Support member 20 Inner chamber 21 Heat-resistant container 30 Heater chamber

Claims (5)

A heater chamber in which a heater is installed is provided in the pressure vessel, and an inner chamber made of a gas-impermeable heat-resistant vessel that can be opened and closed to accommodate a semiconductor single crystal to be processed is provided in the heater chamber. In semiconductor heat treatment equipment,
The heat-resistant container is divided into a lower container part and an upper container part that are in contact with each other via a sealing material, and at least one of the lower container part and the upper container part is attached to a support shaft that can move up and down. A semiconductor heat treatment apparatus, wherein the lower container part and the upper container part are separated from and in contact with each other so that the heat-resistant container can be opened and closed via a sealing material. The semiconductor heat treatment apparatus according to claim 1,
The lower container part is configured as a sample stage, and the upper container part is configured as a container having a lower opening that covers the sample stage airtightly through the sealing material,
A semiconductor heat treatment apparatus characterized by having a structure in which mechanical pressure can be applied from the outside to a joint portion between the sample stage and the upper container by installing in a drive mechanism that allows the support shaft to be moved in the vertical direction. . The semiconductor heat treatment apparatus according to claim 2,
The lower container part and the upper container part are each attached to a support shaft that can move up and down independently,
The upper container part is provided with a collar part around the top part, and this collar part is placed and supported on the top surface of a cylindrical support member which stands up in the pressure container so as to surround the heating element. A semiconductor heat treatment apparatus characterized in that an inner chamber can be formed by bringing a lower container part into contact with a lower opening of an upper container part. In the semiconductor heat processing apparatus in any one of Claims 1-3,
A semiconductor characterized in that the gas-impermeable heat-resistant container is made of graphite having a CVD coating on its surface, a metal material, a ceramic material, a special carbon material having airtightness, or a glass material. Heat treatment equipment. In the semiconductor heat processing apparatus in any one of Claims 1-4,
A semiconductor heat treatment apparatus, characterized in that a graphite foil is used as a material of the sealing material for hermetically holding an open / close portion of the gas-impermeable heat-resistant container.

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