JP2954750B2 - Method and apparatus for manufacturing compound semiconductor crystal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a compound semiconductor crystal of group 3-5 or the like by a boat method such as a horizontal Bridgman method (HB method) or a temperature gradient method (GF method), and an apparatus therefor. It is.

[0002]

2. Description of the Related Art As a method of manufacturing a group 3-5 compound semiconductor single crystal by a boat method, a horizontal Bridgman method (HB
Method) and the temperature gradient method (GF). In the horizontal Bridgman method, an ampoule tube (reaction tube) containing a boat
Is moved in a furnace provided with a predetermined temperature gradient, and the temperature gradient method is a method of moving a temperature profile without moving an ampoule tube. Various researches have already been made on a method and an apparatus for producing a compound semiconductor single crystal by the boat method, for example, Japanese Patent Publication No. 52-19192 and Japanese Utility Model Application Laid-Open No. 1-129273 are disclosed.

[0003] Among the compound semiconductor single crystals, for example, the following method is generally employed as a method of manufacturing a GaAs single crystal by the horizontal Bridgman method.

In a quartz ampoule tube, a quartz single crystal growing boat having a GaAs single crystal seed crystal at one end and a diffusion barrier are arranged, and stoichiometric amounts of GaAs compound or Ga are used as raw materials. After adding the simple substance and the simple substance of As, and further adding the simple substance of the necessary amount to keep the inside of the ampoule tube at approximately 1 atm in the furnace, and the dopant which gives desired electric characteristics as required, vacuum sealing is performed. I do.

[0005] The ampoule tube obtained in this manner is made of GaAs.
In order to obtain a single crystal melt, a GaAs single crystal having a melting point of 1238 ° C. or higher, preferably a high temperature region maintained at about 1250 ° C., and an arsenic gas of approximately 1 atm to maintain the inside of the ampoule tube at 610 ° C. The furnace is placed in a furnace having a low temperature region held before and after and a temperature profile connecting these temperature regions with a gentle temperature gradient.

[0006] Next, in the high temperature region of the furnace, the raw material in the boat is heated to a portion of the ampoule tube where the boat is disposed, to temporarily make a GaAs melt. Then, by moving the ampoule tube and the furnace relatively, the ampoule tube is gradually moved to the low temperature region, and the temperature is gradually lowered from the seed crystal side at one end of the boat to solidify the GaAs melt. To obtain a single crystal.

In this case, as a method of relatively moving the ampule tube and the furnace body, for example, a method shown in FIG. 3 or FIG. 4 has been proposed.

In the method shown in FIG. 3, a furnace core tube 2 is placed through the inside of a furnace body 1, and both ends of the furnace core tube 2 protrude from both ends of the furnace body 1 and are supported on a floor surface. The body 1 is provided movably along the axial direction of the furnace core tube 2, and the ampoule tube 3 is connected to the furnace core tube 2.
In this method, the ampule tube 3 is gradually moved to a low temperature region by moving the furnace body 1 and the melt filled in the boat in the ampule tube 3 is solidified from the end.

Further, in the method shown in FIG. 4, the furnace core tube 2 is fixed to the inner periphery of the furnace body 1, the support plate 4 is inserted into the furnace core tube 2, and the end of the support plate 4 is connected to the support base. The support plate 4 supports the ampule tube 3 on the support plate 4. Then, by moving the furnace body 1 and the furnace core tube 2 in the axial direction, the ampoule tube 3 is gradually moved to the low temperature region, and the melt in the boat in the ampoule tube 3 is solidified from the end. It is.

[0010]

However, in the method shown in FIG. 3, since the furnace core tube 2 is supported only at two points at both ends, sufficient strength is required.
Is made of a material that withstands high temperatures of 1250 ° C and
Must be inert to quartz, which is a constituent material of the above. For this reason, there is a problem that it is difficult to select the material of the furnace core tube 2, and it has to be longer than the furnace body 1, so that the cost becomes too high, and in some cases, the production becomes impossible.

Further, since the furnace body 1 must be moved outside the furnace core tube 2, a gap must be provided between the furnace body 1 and the furnace core tube 2, and the diameter of the furnace body 1 There is also a problem that the size of the crystal that can be manufactured is reduced. Therefore, it was not suitable for growing large and long crystals.

On the other hand, the apparatus shown in FIG. 4 has been proposed for the purpose of solving the above-mentioned problems. However, the apparatus shown in FIG. The furnace body 1 having the above weight must be moved while minimizing the vibration, and there is a problem that the moving mechanism is precise and expensive. In particular, when the crystal becomes longer, the furnace body 1 becomes longer and heavier, making it difficult to produce a smooth moving mechanism. Further, a space for moving the furnace body 1 is required behind the furnace body 1, and there is a problem that the space required increases as the crystal becomes longer.

On the other hand, in the temperature gradient method (GF method), since the furnace body does not need to be moved, the above-described problems such as the moving mechanism and the space do not occur. Then, the number of zones of the heater of the furnace body increases, and the temperature control becomes extremely complicated, which is not practical. Moreover,
Usually, since the crystal observation window is opened at the top of the furnace body over the entire length of the crystal, heat radiation therefrom is large and it is substantially difficult to make the temperature in the furnace a desired distribution, and it is relatively small. Even if short crystals can be grown, it has been difficult to obtain long, large crystals with good crystallinity.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method and an apparatus for manufacturing a compound semiconductor single crystal capable of manufacturing a long crystal with good crystallinity at low cost.

[0015]

According to one aspect of the present invention, there is provided a method of manufacturing a compound semiconductor single crystal by a boat method, comprising: a heater for forming a predetermined temperature distribution; A furnace body is constituted by the placed furnace core tube, and this furnace body is installed on a longer support base,
A support plate longer than the ampoule tube equivalent length is arranged in the furnace core tube, the support plate is movably connected to the support base outside the furnace core tube, and a predetermined raw material is put into a crystal growing boat and an ampoule is placed. The ampoule tube is moved in the furnace core tube by enclosing the ampoule tube on the support plate, disposing the ampule tube in the furnace core tube, and moving the support plate in the longitudinal direction of the furnace body. It is characterized in that it is made to be.

Another aspect of the present invention is a device for manufacturing a compound semiconductor single crystal by the boat method, wherein a heater for forming a predetermined temperature distribution and a furnace core tube disposed inside the heater are provided with a furnace body. The furnace body is installed on a support base longer than that, a support plate longer than the ampoule tube equivalent length is arranged in the furnace core tube, and the support plate is placed on the support base outside the furnace core tube. And a moving mechanism for moving the support plate via the connecting portion.

In a preferred aspect of the present invention, the moving mechanism attaches a connecting member to an end of the support plate, and provides a ball screw on the supporting base, which is screwed with the connecting member and penetrates the connecting member.
It is preferable to provide a driving device for rotating the ball screw. In this case, by rotating the ball screw by the driving mechanism, the support plate can be moved via a connecting member screwed to the ball screw.

In a further preferred aspect of the present invention, the support base includes a fixed base fixedly installed on a floor or the like, an inclined base supported on the fixed base via a horizontal support shaft so as to be tiltable, And a tilt mechanism for tilting the tilt table with respect to the fixed table. In this case, when the tilt table is tilted by the tilt mechanism, the furnace body installed on the tilt table tilts. Thereby, the raw material melt comes into contact with the seed crystal and can be gradually solidified from the seed crystal side.

The support plate for mounting the ampoule tube is preferably inserted into the furnace body from one end of the furnace body, preferably the lower end, and solidified while pulling out from the inserted side. . Further, ceramic powder or the like may be scattered between the support plate and the furnace tube in order to improve the slip of the support plate.

The method and apparatus of the present invention can be applied to the manufacture of Group 3-5 compound semiconductor crystals such as GaAs, InP and InAs and Group 2-6 compound semiconductor crystals such as ZnSe. Further, it can be used not only for producing single crystals of these compound semiconductors but also for producing polycrystals.

[0021]

According to the present invention, as a structure for moving the ampoule tube relatively to the furnace body, the ampoule tube is not moved by the furnace body but is supported by a support plate placed in the furnace core tube of the furnace body. The structure of the device is simplified, the structure of the device is simplified, and the manufacturing cost is reduced as compared with the conventional device for moving a furnace having a considerable weight.

Further, the support plate and the ampule tube are extremely light in comparison with the furnace body, and the support plate on which the ampule tube is mounted is placed in the furnace core tube of the furnace body fixed on the support base. As a result, the vibration caused by the movement is extremely small, and the vibration is prevented from being transmitted to the ampoule tube and adversely affecting the crystallinity. Therefore, a long single crystal with good crystallinity can be obtained with good yield.

Further, it is not necessary to use a furnace core tube longer than the furnace body as shown in FIG. 3, and a space for moving the furnace body as shown in FIG. 4 is not required. Can save money. In addition, when a single crystal is manufactured using a seed crystal, even when a tilting mechanism for a furnace body that is normally used is provided, the support plate and the moving mechanism for the ampule tube have a simple and lightweight structure. Can be made relatively small, easy to manufacture, and inexpensive.

Further, unlike the temperature gradient method (GF method),
Since the temperature distribution in the furnace is fixed in principle, temperature control in the furnace is easy. Furthermore, since the crystal observation window only needs to be opened in a part of the upper part of the furnace body, heat radiation from the crystal observation window is small, a desired temperature distribution is easily obtained, and it is advantageous to obtain a large, long and good quality crystal. It is.

As described above, according to the present invention, the apparatus can be manufactured easily and inexpensively, the temperature distribution in the furnace can be easily controlled to a desired value, and the vibration can be reduced. Therefore, high-quality crystals can be obtained with high yield, and the manufacturing cost of the compound semiconductor can be reduced.

[0026]

【Example】

(Embodiment) FIG. 1 shows an embodiment of an apparatus for producing a compound semiconductor single crystal according to the present invention.

The manufacturing apparatus 11 includes a support table 16 including a fixed table 13 installed on a floor 12 and an inclined table 15 supported by the fixed table 13 via a horizontal support shaft 14 so as to be tiltable. Have. A tilting mechanism 17 that changes the tilt of the tilt base 15 with respect to the fixed base 13 is provided between the fixed base 13 and the tilt base 15.

In this embodiment, the tilting mechanism 17 includes a motor 18 installed on the fixed base 13, an interlocking mechanism 19 such as a pulley, a V-belt, and a worm screw, a ball screw 20, and a ball screw 20 mounted on the tilt base 15. When the motor 18 is operated to rotate the ball screw 20 via the interlocking mechanism 19, the flange 21 screwed to the ball screw 20 moves up and down as shown by the arrow A in the figure. It moves to change the tilt angle of the tilt base 15.

A cylindrical heater 2 is mounted on the inclined table 15.
A furnace body 24 including a furnace core tube 2 and a furnace core tube 23 fixedly disposed therein is provided. The heater 22 is divided in the longitudinal direction into a high-temperature side heater 22a and a low-temperature side heater 22b. 12
Maintain the high temperature range maintained at around 50 ° C, and the heater 22b on the low temperature side maintains the low temperature range maintained at around 610 ° C in order to maintain the inside of the ampoule with almost one atmosphere of arsenic gas. Form a temperature profile connected by a gentle temperature gradient.

Further, above the heater 22a on the high temperature side,
A crystal observation window 25 during growth is provided.

A long support plate 26 is provided inside the furnace body 24, and one end of the support plate 26 projects outward from the low-temperature side end of the furnace body 24. A connector 27 is detachably attached to a portion of the support plate 26 protruding outward, and the connector 27 extends in the direction of the inclined base 15 of the support base 16. A ball screw 30 is rotatably supported on the inclined table 15 via a pair of bearings 28 and 29, and a connecting member 27 is screwed to the ball screw 30. A pulley 31 is attached to one end of the ball screw 30, and is connected to a driving pulley 33 of a motor 32 installed on the inclined base 15 by a belt.

Therefore, when the motor 32 operates, the ball screw 30 rotates via the driving pulley 33, the belt and the pulley 31, and the connecting member 27 screwed to the ball screw 30.
Moves as shown by the arrow B in the figure, and the support plate 26
With respect to the longitudinal direction. In addition,
These devices serve as the moving mechanism 4 of the support plate 26 in the present invention.
1. The support plate 26 is provided with an ampule tube 35 enclosing a boat 34 on which raw materials are placed.

Next, an embodiment of the method of manufacturing a compound semiconductor single crystal of the present invention using the manufacturing apparatus 11 will be described.

7000 g of GaAs polycrystal which is a raw material of GaAs single crystal
Was placed in a quartz boat 34 and put into a quartz ampule tube 34 together with 40 g of As, and the inside was evacuated and sealed. The ampule tube 34 is placed on the support plate 26, and the furnace core tube 23 made of SiC is formed.
Of the heater 22b on the low temperature side. The ampoule tube 34 was initially arranged in the heater 22a on the high temperature side, so that the raw material was heated to become a melt. After the raw material became a melt, the tilting table 17 was tilted by the tilting mechanism 17 to bring the melt into contact with a seed crystal installed at one end of the boat 34.

Thereafter, the motor 32 in the moving mechanism 41
To rotate the ball screw 30 so that the support plate 26
Is gradually pulled out of the furnace body 24, and the boat 34 installed in the ampule tube 35 is moved from the seed crystal side to the low temperature region of the heater 22b. Thus, the melt was gradually solidified from the seed crystal side to obtain a GaAs single crystal.

The single crystal thus obtained has a total length of 800 mm.
, Weighed 4000 g, and were high-quality crystals over the entire length. Although similar crystal growth was repeated, a high-quality single crystal with good reproducibility was obtained. Further, since the moving mechanism 41 of the support plate 26 only needs to be moved by the load of the ampule tube 34, the moving mechanism 41 is not complicated in structure but is an inexpensive mechanism. The total length of the manufacturing apparatus 11 was 5900 mm, and the installation space was small. Further, the maximum amplitude due to the movement of the support plate 26 measured at the position of the ampoule tube 34 during the crystal growth was 5 μm.

(Comparative Example) FIG. 2 shows an apparatus for manufacturing a compound semiconductor single crystal manufactured for comparison. In the figure, parts that are substantially the same as those in FIG. 1 are given the same reference numerals, and descriptions thereof will be omitted.

The manufacturing apparatus 51 is basically the same as the apparatus shown in FIG. 4. In order to make the furnace body 24 tiltable, the tilting table 15 of the support 16 is tilted by the tilting mechanism 17. And a point that a moving mechanism 52 for moving the furnace body 24 is provided, and that an ampule tube insertion table 53 for placing the ampule tube 35 on the support plate 26 and inserting the ampule tube 35 into the furnace body 24 is provided. Is different.

The furnace body 24 is movably mounted on the inclined table 15 by a bearing mechanism 54. In the furnace body 24,
A flange 55 extending in the direction of the inclined table 15 is provided,
A ball screw 58 supported on the inclined table 15 via bearings 56 and 57 is screwed into the flange 55 and penetrated therethrough. A pulley 59 is mounted on one end of the ball screw 58, and the pulley 59 is connected to a driving pulley 61 of a motor 60 by a belt.

Therefore, when the motor 60 operates, the ball screw 58 rotates via the drive pulley 61, the belt and the pulley 59, and the flange 55 screwed to the ball screw 58 moves, so that the furnace body 24 is placed on the inclined base 15. It is designed to move with. These devices constitute the moving mechanism 52.

One end of the support plate 26 is detachably fixed to a holder 62 erected from the inclined table 15 during the crystal growing operation. When the ampule tube 35 is inserted and removed, it is connected to the ampule tube insertion table 53. It is configured to be removably fixed to the attached holder 63. The ampoule tube insertion base 53 is installed on the floor surface 12 adjacent to the support base 16, and a ball screw 66 is rotatably supported via bearings 64 and 65. The ball screw 66 is screwed to the holder 63. Through. A pulley 67 is attached to one end of the ball screw 66, and the pulley 67 is connected to a driving pulley 69 of a motor 68 by a belt.

Therefore, when the motor 68 is operated, the ball screw 66 is rotated via the driving pulley 69, the belt and the pulley 67, and the holder 63 screwed to the ball screw 66 is moved to the furnace body 24 of the support plate 26. Insertion and withdrawal are made.

Next, a GaAs single crystal was manufactured by using the same raw material as in the embodiment using this manufacturing apparatus 51. That is, in the same manner as in the embodiment, the raw material GaAs polycrystal was
, And sealed in an ampoule tube 35 together with As. The ampule tube 35 was placed on the support plate 26, and the support plate 26 was inserted into the furnace body 24 by the ampule tube insertion stand 53. Ampoule tube 3
5 was positioned inside the heater 22a on the high temperature side of the furnace body 24, and the support plate 26 was fixed to the inclined table 15 by the holder 62 in this state.

After the raw material was heated to obtain a melt, the furnace body 24 was tilted by the tilting mechanism 17 to bring the melt into contact with the seed crystal. In this state, the furnace body 24 is moved by the moving mechanism 52.
Was gradually moved backward, the ampoule tube 35 was moved to the low-temperature side heater 22b side, and the melt was solidified from the seed crystal side to obtain a GaAs single crystal.

In the single crystal thus obtained, twin defects were liable to be formed, and as a result of repeated crystal growth, the yield was lower than that of the above example. In addition, since the manufacturing apparatus 51 moves the extremely heavy furnace body 24, the moving mechanism 52 requires an expensive bearing mechanism 54 and a powerful motor 60.
And the like, and the equipment cost becomes extremely high.

Further, despite the adoption of such an expensive mechanism, the maximum amplitude accompanying the movement of the furnace body 24 measured at the position of the ampoule tube 35 during crystal growth is 15 μm, 3 times larger than the device 11,
This is considered to be the cause of the twin defect. The total length of the manufacturing apparatus 51 including the ampoule tube insertion table 53 is 6700 mm, which is 800 mm longer than that of the manufacturing apparatus 11 of the embodiment, and requires a larger installation space for the apparatus.

[0047]

As described above, according to the manufacturing method of the present invention, the vibration applied to the ampoule tube during the crystal growth can be made very small, and as a result, the compound semiconductor crystal having few crystal defects can be produced at a high yield. Can be manufactured well. Further, according to the manufacturing apparatus of the present invention, since the ampoule tube is moved together with the support plate, the moving mechanism can be reduced in size with a simple structure, easy to manufacture, and inexpensive to manufacture. And the installation space of the device is small. Therefore, according to the present invention,
A long and elongate group III-V compound semiconductor crystal can be obtained more easily and at lower cost.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing one embodiment of an apparatus for producing a compound semiconductor single crystal according to the present invention.

FIG. 2 is a schematic side view showing an apparatus for manufacturing a compound semiconductor single crystal manufactured for comparison with the present invention.

FIG. 3 is a schematic side view showing an example of a conventional compound semiconductor single crystal manufacturing apparatus.

FIG. 4 is a schematic side view showing another example of a conventional compound semiconductor single crystal manufacturing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Manufacturing apparatus of compound semiconductor single crystal 12 Floor 13 Fixing stand 14 Support shaft 15 Inclined stand 16 Supporting stand 17 Tilt mechanism 22 Heater 22a High temperature side heater 22b Low temperature side heater 23 Furnace tube 24 Furnace body 26 Support plate 27 Connection Tools 34 Boat 35 Ampoule tube 41 Moving mechanism

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-18374 (JP, A) JP-A-1-129273 (JP, U) JP-B-54-6035 (JP, B2) JP-B-57- 39179 (JP, B2) JP-B 55-23236 (JP, B2) JP-B 52-19192 (JP, B2) JP-B 54-35195 (JP, B2) (58) Fields surveyed (Int. ⁶ , DB name) C30B 1/00-35/00

Claims (6)

(57) [Claims] In a method of manufacturing a compound semiconductor crystal by a boat method, a furnace for forming a predetermined temperature distribution and a furnace core tube disposed inside the heater constitute a furnace body. A support plate longer than the equivalent length of the ampoule tube is disposed in the furnace core tube, and this support plate is movably connected to the support base outside the furnace core tube to grow crystals. A predetermined raw material is put in a boat and sealed in an ampoule tube, the ampoule tube is placed on the support plate and arranged in the furnace core tube, and the support plate is moved in the longitudinal direction of the furnace body, A method for producing a compound semiconductor crystal, wherein the ampoule tube is moved within the furnace core tube. 2. A support is attached to an end of said support plate, and a ball screw is screwed into said connector and provided on said support base, and said support plate is moved by rotating said ball screw. 1. The method for producing a compound semiconductor crystal according to 1 above. 3. The method for producing a compound semiconductor crystal according to claim 1, wherein the furnace body is tilted to bring the raw material melt into contact with the seed crystal and gradually solidify from the seed crystal side. 4. An apparatus for producing a compound semiconductor crystal by a boat method, wherein a heater for forming a predetermined temperature distribution and a furnace core tube disposed inside the heater constitute a furnace body. A support plate longer than the ampoule tube equivalent length is disposed in the furnace core tube, and the support plate is movably connected to the support base outside the furnace core tube, An apparatus for producing a compound semiconductor crystal, comprising a moving mechanism for moving the support plate via a part. 5. The moving mechanism according to claim 1, wherein a connecting tool is attached to an end of the support plate, a ball screw is screwed into the connecting tool and provided on the support base, and a driving device for rotating the ball screw is provided. 5. The apparatus for producing a compound semiconductor crystal according to claim 4, wherein the apparatus comprises: 6. The support base is a fixed base fixed to a floor or the like, a tilt base supported on the fixed base via a horizontal support shaft, and a tilt base supported by the fixed base. And a tilting mechanism for tilting with respect to.
For manufacturing compound semiconductor crystals.