JPH0450189A - Method and apparatus for production of compound semiconductor single crystal - Google Patents

Abstract

PURPOSE:To enable regulation of temperature gradient near a crystal observation window with excellent reproducibility by regulating the temperature distribution in the longitudinal direction of a furnace with a main heater and the temperature distribution in the vertical directions with an auxiliary heater. CONSTITUTION:A furnace core tube 13 equipped with a reaction tube 14 housing a boat 15 containing a raw material is installed on the inner periphery of a main heater 20 arranged on the inner periphery of a slender vessel-like or cylindrical heat insulating material 12 having a crystal observation window 16 formed in the upper wall part. The main heater 20 is divided into plural zones 21 to 28 so as to form a prescribed temperature distribution in the longitudinal direction. An auxiliary heater 17 having a length the same as or greater than that of a window 16 in the longitudinal direction of the furnace body on both sides in the longitudinal direction of the furnace body is arranged in the zone 24 of the main heater 20. An electric power applied to the respective zones 21 to 28 of the main heater 20 is then controlled to regulate the temperature gradient in the longitudinal direction of the furnace body. The electric power is applied to the auxiliary heater 17 to regulate the temperature gradient in the vertical directions of the furnace body.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a method and apparatus for manufacturing compound semiconductor single crystals such as m-V group by boat method.

"Prior Art" In recent years, in the field of electronics industry, GaAs and InP, which have few crystal defects such as dislocations and lineages, have been used.

Various methods of manufacturing compound semiconductor single crystals such as InAs at low cost are being studied.

The boat method and the pulling method are known as methods for manufacturing compound semiconductor single crystals, but the boat method has a smaller temperature gradient (and stoichiometry) than the pulling method.
Since it is easy to control, it has the advantage of being able to grow single crystals with few crystal defects.

The boat method includes the horizontal Bridgman method (FIB method) and the temperature gradient method (GF method), both of which use a horizontal furnace in which a raw material melt is placed in a long boat and a temperature gradient is created in the longitudinal direction. This method produces a single crystal by solidifying the crystal from one end of the boat.

Since the boat method has a small temperature gradient, it is important to accurately control the temperature distribution in the furnace, especially the temperature distribution near the solid-liquid interface. In addition, since crystallization starts from the free surface of the raw material melt and progresses toward the bottom of the boat, it is necessary to accurately control the temperature gradient in the longitudinal direction of the furnace as well as the temperature gradient in the vertical direction of the furnace. .

FIG. 4 shows an apparatus disclosed in Japanese Patent Application Laid-open No. 153184/1984 as an example of a conventional single crystal manufacturing apparatus using the boat method.

In this device, a boat 5 containing a raw material melt 6 is enclosed in an ampoule tube 4 made of quartz, and the ampoule tube 4 is placed in a furnace. The furnace includes a heater 3 surrounding the ampoule tube 4, a heat insulating material 2 covering the outer periphery of the heater 3, and a heat insulating material 2.
It consists of a casing 1 surrounding the outside of the casing 1. A heat dissipation port is provided above the heat insulating material 2 and the heater 3 to dissipate the heat of the raw material melt, and a glass plate 8 is fitted into this heat dissipation port to serve as a window for crystal observation that also serves as heat dissipation. . In this conventional example, movable walls 9 are arranged on both sides of the heat radiation port, and the volume of the space above the glass plate 8 is changed to adjust the amount of heat radiation, thereby controlling the temperature of the upper layer of the raw material melt 6. It is a feature.

Further, FIG. 5 shows an apparatus disclosed in Japanese Patent Application Laid-Open No. 1219091 as another example of a conventional single crystal manufacturing apparatus using the boat method.

Note that the same parts as in FIG. 4 are given the same reference numerals.

This device is basically the same as the device shown in FIG. 4, but a frame 7 is attached to the heat radiation port, and a glass plate 8 is fitted into the frame 7. The height of the glass plate 8 is changed by replacing the frame 7 or the like, thereby adjusting the amount of heat radiation and controlling the temperature of the upper layer of the raw material melt 6.

These conventional devices control the temperature distribution in the vertical direction within the furnace by changing the structure of the heat radiation port portion of the furnace body.

On the other hand, in Special Publication No. 59-38185, Figure 6 (a)
A horizontal furnace shown in (b) has been proposed.

In Fig. 6, A2 and A3 are high temperature heating parts, B2 and B3
1 is a medium temperature heating section, C2 and C8 are low temperature heating sections, and 10 is a crystal observation window where the solid-liquid interface of the raw material melt exists. The furnace shown in FIG. 6(a) is provided with heating bodies a, b, C, and d divided into two vertically, respectively, on the crystal observation window 10 side of heating parts A2 and B2, and is composed of a tubular heating body 11. Further, in the furnace shown in FIG. 6(B), the heating furnace on the side of the crystal observation window 10 of the heating section A3 is composed of heating elements a and b, and the heating furnace on the side of the crystal observation window 10 of the heating section B3 is
One more tubular heating element 11° is provided on the side, and the other heating furnace is composed of tubular heating elements 11.

In this conventional example, heating elements a, b, c, d, 11.
By independently controlling the amount of power applied to each element, the temperature distribution in the long axis direction of the furnace and the temperature distribution in the vertical direction of the furnace, especially near the solid-liquid interface, can be controlled to a predetermined distribution. It is characterized by That is, in this conventional device, temperature control is attempted to be adjusted by the amount of electric power applied to the heating element.

"Problem to be solved by the invention" However, JP-A-62-153184, JP-A-1
-219091, which controls the temperature gradient in the vertical direction by changing the structure of the heat dissipation port of the furnace body, requires the position of the temperature adjustment jig, the glass There was a problem in that the temperature inside the furnace had to be measured by changing the position of the plate, which required time and effort. In addition, the optimal temperature gradient differs slightly depending on the type, size, length, etc. of the single crystal, so the jig and glass plate must be adjusted every time the desired single crystal changes. It was efficient. Furthermore, in the above-mentioned apparatus, the temperature range in which the temperature gradient can be changed is also small, and there is a problem in that sufficient adjustment cannot be made. Furthermore, since the furnace body, casing, glass plate, etc. are exposed to high temperatures for long periods of time, they tend to undergo thermal deformation, and even after adjusting the temperature gradient, these deformations may cause the temperature gradient to not reach the desired level. In some cases, the value deviated from the value, which adversely affected the quality of the crystal.

On the other hand, the device shown in Japanese Patent Publication No. 59-38185 that divides the heating element into multiple parts and controls the temperature gradient by adjusting the power applied to each heating element is a control method based on fine adjustment of the amount of electric power. Therefore, compared to the method of controlling by changing the structure of the furnace body, this method has the advantage that a desired temperature gradient can be obtained in a short time and with good reproducibility. However, in the above-mentioned apparatus, three or more zones of independently controlled heating elements are provided on both sides of the crystal observation window, and these zones independently control the temperature gradient in the longitudinal direction and the temperature gradient in the vertical direction. For example, after setting the temperature gradient in the long axis direction to a desired value,
When the temperature in the vertical direction is adjusted, a deviation occurs in the temperature in the longitudinal direction, and readjustment is required.Therefore, there is a problem in that temperature adjustment takes time and effort. In order to finely adjust the temperature gradient, the more heating elements are used, the longer it takes to adjust the temperature, so a great deal of skill is required to obtain an ideal temperature distribution.

In addition, due to its structure, the heating element, which is divided into a plurality of parts and provided near the crystal observation window, uses a heater wire such as a Kanthal wire, which is normally used as a heating element, that is folded in a corrugated manner in the longitudinal direction or the circumferential direction. Because it uses special surface heating elements such as ceramics, it is necessary to create it separately from the main heating element, which is created with a normal spiral structure, and then combine it. There was also the problem that the heating element was complicated and the cost of the heating element was high.Also, the heating element was divided into multiple parts near the crystal observation window.
Since Kanthal wire also plays the role of maintaining the temperature inside the furnace, it requires a large amount of electric power to be applied, and as a result, the service life of Kanthal wire is short (and maintenance costs are also high).

The present invention has been made in view of the problems of the prior art described above, and its purpose is to easily and reproducibly adjust the temperature gradient in the furnace, especially the temperature gradient near the crystal observation window, to a desired value. It is an object of the present invention to provide a method and apparatus for manufacturing a compound semiconductor single crystal, which can reduce the manufacturing cost and improve the life of the device.

[Means for Solving the Problems] In order to achieve the above object, the method for manufacturing a compound semiconductor single crystal of the present invention includes: enclosing a boat loaded with raw materials in an ampoule tube; A method for manufacturing a compound semiconductor single crystal by a boat method in which the raw material melt in the boat is placed in a furnace and gradually solidified from one end to obtain a single crystal, wherein a window for crystal observation is provided in the upper part of the furnace. forming and installing a main heater having a plurality of zones in which the applied power can be independently controlled along the length of the furnace;
Further, an auxiliary heater is attached redundantly to the main heater near the crystal observation window, the main heater adjusts the temperature distribution in the longitudinal direction of the furnace, and the auxiliary heater adjusts the temperature distribution in the vertical direction of the furnace. The method is characterized in that the raw material melt is solidified by adjusting the .

Further, in the compound semiconductor single crystal manufacturing apparatus of the present invention, a boat loaded with raw materials is sealed in an ampoule tube, the ampoule tube is placed in a furnace having a predetermined temperature distribution, and the raw material melt in the boat is heated. In an apparatus for producing a compound semiconductor single crystal using a boat method in which a single crystal is obtained by gradually solidifying from one end, the ampoule tube is housed (the ampoule tube has an elongated container shape extending in the horizontal direction as a whole, and the upper wall portion is A heat insulating material in which crystal observation windows are formed at predetermined locations; a main heater that is placed inside the insulating material and has multiple zones along the longitudinal direction, and can independently control applied power in each zone; In the vicinity of the crystal observation window,
The furnace is configured by an auxiliary heater which is arranged to overlap with the main heater and whose applied power can be independently controlled; the main heater adjusts the temperature distribution in the longitudinal direction of the furnace; It is characterized in that the temperature distribution in the vertical direction of the furnace is adjusted to solidify the raw material melt.

In the present invention, it is preferable that the auxiliary heater has a length equal to or longer than the length in the longitudinal direction of the crystal observation window.

Further, the auxiliary heater is preferably arranged outside the main heater in one zone of the main heater located near the crystal observation window, or may be arranged inside the main heater.

"Operation" In the present invention, the main heater is arranged over the entire longitudinal direction of the furnace, and the auxiliary heater is arranged near the crystal observation window and overlaps with the outside of the main heater. in this way,
The main heater is also placed in the area where the auxiliary heater is placed, and the main heater maintains the basic temperature distribution along the longitudinal direction of the furnace, so the auxiliary heater is placed near the crystal observation window. It is sufficient that the amount of heat generated is sufficient to adjust the temperature distribution in the vertical direction inside the furnace. That is, the electric power of the auxiliary heater may be relatively small. In other words, the apparatus can be manufactured by simply attaching a simple auxiliary heater to the main heater arranged along the entire length of the furnace. Therefore, unlike the device shown in Japanese Patent Publication No. 59-38185, there is no need for the complicated work of separately manufacturing and assembling multiple heating bodies divided into longitudinal and vertical directions of the furnace. , the device can be manufactured inexpensively and easily.

Furthermore, in the present invention, the main heater forms the basic temperature distribution along the longitudinal direction of the furnace, and the auxiliary heater adjusts the temperature distribution in the vertical direction inside the furnace near the crystal observation window. , the temperature distribution in the furnace can be easily controlled compared to the method shown in Japanese Patent Publication No. 59-38185, in which the temperature distribution in both the longitudinal direction and the vertical direction of the furnace is adjusted using heating elements divided into upper and lower parts. Therefore, it takes only a short time to adjust the temperature to obtain the desired temperature distribution.

Furthermore, since the power applied to the auxiliary heater can be small,
Its service life will be longer.

As described above, according to the present invention, the apparatus can be manufactured easily and at low cost, and the temperature distribution in the longitudinal direction and vertical direction of the furnace can be controlled in a short period of time with good reproducibility (controllable This makes it possible to reduce the manufacturing cost of compound semiconductor single crystals.

Embodiment FIGS. 1 and 2 show an embodiment of the compound semiconductor single crystal manufacturing apparatus of the present invention.

This device has a heat insulating material 12 that has an elongated container shape or a cylindrical shape that extends horizontally as a whole, and a crystal observation window 16 is formed in the upper wall of the heat insulating material 12. Insulation material 1
A main heater 20 is arranged on the inner periphery of the main heater 2 . Further, on the inner periphery of the main heater 20, there is a quartz furnace core tube (uniform heating tube).
13 are arranged. In this furnace core tube 13,
An ampoule tube (reaction tube) 14 containing a boat 15 containing raw materials is installed. Note that the outside of the heat insulating material 12 may be further covered with a casing,
A lid such as a glass plate may be fitted into the crystal observation window 16.

The main heater 20 has a plurality of zones 21 to 2 along the longitudinal direction so as to form a predetermined temperature distribution in the longitudinal direction of the furnace body.
It is divided into 8 sections. In this embodiment, the main heater 20
has a structure in which Kanthal wires or the like are formed in a spiral shape.

The heater wires constituting the main heater 20 are in zones 21 to 28.
There are one or at most two or three wires for each zone, and a terminal is provided for each zone so that electric power can be applied independently.

Auxiliary heaters 17 are arranged on both sides of the crystal observation window 16 of the heat insulating material 12 along the longitudinal direction of the furnace body. This auxiliary heater 17 has a length that is equal to or longer than the length of the crystal observation window 16 along the longitudinal direction of the furnace body so that the amount of heat dissipated from the crystal observation window 16 can be sufficiently supplemented. There is. In addition, in order to avoid complicating the control of the main heater 20 due to the influence of the auxiliary heater 17, the auxiliary heater 17 is placed at the position of the crystal observation window 16 of the main heater 20.
are arranged within one zone 24.

Further, as shown in FIG. 1, the auxiliary heater 17 is arranged on the outside of the main heater 20 and inside the heat insulating material 12 in order to maximize thermal efficiency. In this embodiment, the auxiliary heater 17 is composed of a heater wire folded into a waveform. Note that in order to prevent an electrical short circuit between the auxiliary heater 17 and the main heater 20, it is preferable that the heater wire of the auxiliary heater 17 be placed inside an insulating tube.

In this device, a heat insulating material 12, a main heater 20, a furnace core tube 13
and the auxiliary heater 17 constitute a furnace body. Although not shown, the ampoule tube 14 is connected to the furnace core tube 13.
Means is provided for relatively moving the ampoule tube 14 and the furnace body while disposed within the ampoule tube 14. As a means of this,
For example, a method is employed in which the ampoule tube 14 is held by a support rod and the furnace body is moved. In this way, the ampoule tube 14
A single crystal can be produced by gradually solidifying the raw material melt entering the inner boat 15 from the end of the boat 15.

FIG. 3 shows another embodiment of the compound semiconductor single crystal manufacturing apparatus of the present invention.

In this device, the auxiliary heater 17 is constructed of a known surface heater made of conductive ceramics, etc., and the structure of the other parts is the same as the device shown in FIGS. 1 and 2.
The explanation will be omitted.

Test Example The device shown in FIGS. 1 and 2 (hereinafter referred to as the device of the example) and the conventional device shown in FIG. 6 (a) (hereinafter referred to as the conventional device) were manufactured. , in each device,
GaAs single crystals were manufactured and the manufacturing costs of the equipment, the time required for adjustment to obtain the desired temperature gradient, the time until the furnace became unusable due to deterioration, and the quality of the resulting single crystals were compared.

(a) Manufacturing cost of the device In the device of the embodiment, the main heater 20 is constituted by a heater with a spiral structure made of a general Kanthal wire, and the auxiliary heater 1
7 was made of heater wires folded into a waveform.

On the other hand, in the conventional apparatus, the heating elements a, b, c, and d provided near the crystal observation window are formed of heater wires folded in a waveform, and the heating elements are arranged at an angle of 11.11° along the longitudinal direction of the furnace body. was formed using a spiral-structured heater made of Kanthal wire, and was manufactured by combining each heating element.

A comparison of the manufacturing costs of the devices manufactured in this way revealed that the device of the example could be manufactured at approximately 70% of the cost of the conventional device.

(b) Time required for adjustment to obtain a desired temperature gradient In the apparatus of the embodiment, the temperature gradient in the longitudinal direction of the furnace body is
The electric power applied to each zone 21 to 28 of the main heater 20 was controlled and adjusted to a desired value. After that, the auxiliary heater 17
Electric power was applied to adjust the temperature gradient in the vertical direction. The temperature gradient in the vertical direction could be adjusted by simply applying a small amount of electric power to the auxiliary heater 17, without affecting the pre-adjusted temperature gradient in the longitudinal direction.

In the conventional apparatus, after adjusting the temperature gradient in the longitudinal direction of the furnace body by applying electric power to the heating elements 11 and 11, electric power is applied to the heating elements a, b, c, and d near the crystal observation window. to adjust the temperature gradient in the vertical direction. However, the heating elements a, b,
By applying power to c and d, a shift occurred in the temperature gradient in the longitudinal direction, so readjust the power applied to heating element 11.11° and repeat these operations to obtain the desired temperature gradient. was completed.

As a result, the time required to achieve the desired temperature gradient in the apparatus of the example was about half that of the conventional apparatus.

(c) Time until the furnace becomes unusable due to deterioration GaAs single crystals were produced using the apparatus of the example and the conventional apparatus, with the raw materials, crystal growth ports, ampoule tubes, etc. being the same.

The furnace of the apparatus of the example became unusable after about 30 months due to deterioration, whereas the conventional apparatus became unusable after about 15 months. That is, the device of the example could be used without maintenance for about twice as long as the conventional device.

(d) Quality of manufactured single crystal A comparison of crystal defects, electrical properties, etc. between the GaAs single crystal manufactured using the apparatus of the example and the GaAs single crystal manufactured using the conventional apparatus revealed that The quality was the same.

"Effects of the Invention" As explained above, according to the method of manufacturing a compound semiconductor single crystal of the ■-V group, etc. of the present invention, the furnace is adjusted to a desired temperature gradient.
Adjustments can be made easily and with good reproducibility in a short time.

In addition, the compound semiconductor single crystal manufacturing apparatus of the present invention has a simple structure, so it is easy to manufacture and the manufacturing cost is low.In addition, since it takes a long time to become unusable due to deterioration, maintenance costs are reduced. It's cheap.

That is, according to the present invention, a single crystal having the same quality as a single crystal produced using a conventional apparatus can be easily produced at a low cost.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the compound semiconductor single crystal manufacturing apparatus of the present invention, FIG. 2 is a plan sectional view of the same apparatus, and FIG. 3 is a cross-sectional view of the compound semiconductor single crystal manufacturing apparatus of the present invention. 4 and 5 are cross-sectional views showing different examples of the conventional compound semiconductor single crystal manufacturing apparatus, and FIGS. 6 (a) and (b) are cross-sectional views showing the conventional FIG. 3 is a longitudinal cross-sectional view showing still another example of a compound semiconductor single crystal manufacturing apparatus. In the figure, 12 is a heat insulating material, 13 is a furnace core tube, 14 is an ampoule tube, 15 is a boat, 16 is a crystal observation window, 17 is an auxiliary heater, 20 is a main heater, and 21 to 28 are each zone of the main heater. be. Map area

Claims (4)

[Claims] (1) A boat loaded with raw materials is sealed in an ampoule tube, the ampoule tube is placed in a furnace with a predetermined temperature distribution, and the raw material melt in the boat is gradually solidified from one end to obtain a single crystal. In the method for manufacturing a compound semiconductor single crystal by the boat method, a main heater has a crystal observation window formed in the upper part of the furnace, and has a plurality of zones in which applied power can be independently controlled along the longitudinal direction of the furnace. and an auxiliary heater is attached redundantly to the main heater near the crystal observation window, the main heater adjusts the temperature distribution in the longitudinal direction of the furnace, and the auxiliary heater adjusts the temperature distribution in the vertical direction of the furnace. A method for producing a compound semiconductor single crystal, comprising solidifying a raw material melt by adjusting the temperature distribution of the compound semiconductor. (2) Enclose the boat carrying the raw material in an ampoule tube, place this ampoule tube in a furnace with a predetermined temperature distribution, and gradually solidify the raw material melt in the boat from one end to obtain a single crystal. In the apparatus for producing compound semiconductor single crystals using the boat method, the container has an elongated container shape extending horizontally as a whole to accommodate the ampoule tube, and a crystal observation window is formed at a predetermined location on the upper wall. a heat insulating material; a main heater disposed inside the heat insulating material and having a plurality of zones along the longitudinal direction and capable of independently controlling applied power in each zone; and a main heater in the vicinity of the crystal observation window; The furnace is configured by an auxiliary heater which is placed overlapping the heater and whose applied power can be independently controlled.The main heater adjusts the temperature distribution in the longitudinal direction of the furnace, and the auxiliary heater adjusts the temperature distribution of the furnace. 1. A compound semiconductor single crystal production apparatus characterized in that a raw material melt is solidified by adjusting the temperature distribution in the vertical direction. (3) The compound semiconductor single crystal manufacturing apparatus according to claim 2, wherein the auxiliary heater has a length that is equal to or longer than the length in the longitudinal direction of the crystal observation window. (4) The compound semiconductor single crystal manufacturing apparatus according to claim 2 or 3, wherein the auxiliary heater is arranged in one zone of the main heater located near the crystal observation window.