JPH07510B2 - Compound semiconductor crystal manufacturing equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for producing a single crystal by solution growth of a compound semiconductor.

(Problems to be Solved by Prior Art and Invention) FIG. 4 is an example of a schematic cross-sectional view of a single crystal growth apparatus used in a synthetic solute diffusion method, which is a type of conventional solution growth method for compound semiconductors. In the figure, 1 is a high temperature furnace, 2 is a low temperature furnace, 3 is a quartz ampoule, 4 is a crucible bottom plate, 5 is a crucible bottom plate also serving as a heat sink, 6 is a seed crystal, and 7 is a second compound.
Constituent element, 8 is the first using the first constituent element of the compound as a solvent
A solution of the element and the second element, 9 is a single crystal of the compound semiconductor crystallized from the solution 8, and 10 is a driving unit.
This type of apparatus basically comprises a high temperature furnace 1 and a low temperature furnace 2, and a desired temperature distribution as shown in FIG. 4B is obtained by adjusting the relative positions of these. The crucible comprises a crucible cylinder 4 and a crucible bottom plate 5, and has a structure in which a seed crystal 6 can be fixed to the upper part of the crucible bottom plate. The first constituent element is put in this and stored in the high temperature part side of the ampoule 3. The second constituent element 7 is stored in the bottom of the ampoule 3 on the low temperature side. Usually, the first element is a component that is hard to evaporate, and the second element is a component that is easy to evaporate. After storing the raw material, the ampoule 3 is vacuum-sealed. The method for growing a single crystal using this type of apparatus is as follows. First, the temperature inside the ampoule 3 is raised to evaporate the second element 7 and transport it into the crucible. Thereby, the first element and the second element react with each other to prepare the compound solution 8. When the ampoule 3 is gradually lowered by the driving unit 10, the bottom of the solution 8 reaches the temperature T _G and becomes supersaturated. As a result, a single crystal 9 of the compound crystallizes on the seed crystal 6. After that, this process proceeds continuously, and the whole solution 8 becomes the single crystal 9. Although the solution growth has been described above, in the case of melt growth, T _G
Is a melting point, and if the solution 8 is a melt, single crystal growth is performed according to the same principle. However, the melt is prepared by the direct reaction of the constituent elements as described above, or the polycrystal of the compound synthesized in advance is used. Conventionally, the following problems have been encountered in growing a single crystal using such an apparatus configuration.

(A) When the constituent elements react to prepare the solution 8, it takes a considerable time until the solution 8 becomes a saturated solution. During this time, the seed crystal is in contact with the unsaturated liquid,
There was a problem that the seeds could not be seeded by eluting into the unsaturated liquid.

(B) In order to improve the above problems, there is a method in which a polycrystal of a compound is added at the same time in addition to the first constituent element to shorten the preparation time of the saturated solution. However, this method not only loses the merit of obtaining a single crystal from the direct reaction of the constituent elements, but also when the dissolution of the polycrystal is incomplete,
There is a problem that this undissolved polycrystal acts as a new seed crystal and hinders single crystal growth.

(C) The seed crystal 6 is in contact with the crucible cylinder 4, but crystal nuclei are easily generated in this portion. Therefore, there has been a problem that twinning or polycrystallization of crystals is likely to occur and the yield of single crystal growth is reduced.

For this reason, in the present situation, a single crystal of high quality cannot be obtained with the above-mentioned device configuration, and it is hardly industrially usable.

(Object of the Invention) An object of the present invention is to provide a compound semiconductor crystal manufacturing apparatus capable of eliminating these defects and industrially obtaining a good quality compound semiconductor.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an ampoule, a crucible arranged in the ampoule with a gap between the ampoule, and an opening side of the crucible. And a fixing jig for fixing the upper part of the seed crystal arranged in the pipe partition, and a pipe partition inserted in the crucible with a gap therebetween. The heat sink for releasing heat to the upper part, the raw material storage part other than the crucible, and the outer circumference of the ampoule are arranged to cause a temperature distribution in the tube direction of the ampoule, and the raw material storage part is stored in this. The temperature of the crucible part is sufficient to melt the raw material to be vaporized, and the temperature of the crucible portion is gradually lowered from below the crucible to above the heat sink and above the heat sink. Like temperature SUMMARY OF THE INVENTION A gist of the invention is a compound semiconductor crystal manufacturing apparatus characterized in that it has a furnace for holding the ampoule and a vertical moving mechanism for the ampoule.

Furthermore, the present invention provides an ampoule, a crucible made of a material having a good thermal conductivity, which is arranged in the ampoule with a gap between the ampoule, and the crucible is inserted from the opening side of the crucible,
A pipe partition wall having a fold back at the bottom, which is arranged with a gap between the crucible, a fixing jig for fixing the upper part of the seed crystal arranged in the pipe partition wall, and an upper part of the seed crystal. The heat sink for releasing heat to the upper part, the raw material storage portion other than the crucible, and the raw material storage portion disposed around the ampoule and causing a temperature distribution in the tube direction of the ampoule. The temperature of the raw material to be stored is sufficient to evaporate, the temperature of the crucible portion is sufficient to melt the raw material to be stored therein, and the temperature gradually decreases from below the crucible to above the heat sink and above the heat sink. The gist of the invention is a compound semiconductor crystal manufacturing apparatus characterized by having a furnace for maintaining such a temperature and a vertical moving mechanism for the ampoule.

Therefore, in the present invention, the seed crystal is brought into contact with the unsaturated solution, and further, in order to create a situation in which only the seed crystal and the saturated solution are in contact with each other at the start of crystal growth, the seed crystal is not in the crucible bottom but in the solution top. It is characterized by being placed in.

Next, examples of the present invention will be described.

Needless to say, the embodiment is merely an example, and various modifications and improvements can be made without departing from the spirit of the present invention.

FIG. 1 is a first embodiment of the present invention, which is applied to the growth of InP single crystal. (A) In the figure, 1 is a high temperature furnace, 2
Is a low temperature furnace, 3 is a quartz ampoule, 6 is a seed crystal, 9 is a compound semiconductor single crystal, 11 is phosphorus (P), 12 is a solution of indium and phosphorus (P), 13 is a quartz pipe partition wall, and 14 is a quartz crucible. Blocks 15 made of AlN or BN serve as a jig for fixing the seed crystal 6 and a heat sink for latent heat. Quartz pipe bulkhead 13
Is welded to the ampoule 3 at the upper part and separates the In-P solution 12 in the quartz crucible 14 fixed by the protrusion 16 into a single crystal growth region and a solute supply region.

Single crystal growth by this apparatus is performed as follows. First, the raw material In is stored in the quartz crucible 14. When the temperature is raised, phosphorus (P) 11 evaporates and is supplied into the In melt from the clearance between the quartz pipe partition wall 13 and the quartz crucible 14. First, phosphorus (P) gas passes through the In melt and diffuses to the upper part of the ampoule, but eventually reacts with In to form an In-P solution. The volume of this solution increases and the liquid level rises as it approaches saturation. However, since the excess solution overflows from the upper part of the crucible, the position of the liquid surface cannot be higher than the upper surface of the crucible. That is, the seeding position is automatically determined. The latent heat during crystallization is released through the seed crystal 6 and the heat sink 15. Therefore, the temperature around the seed crystal 6 becomes the lowest at the time of seeding. Further, since the seed crystal 6 is not in contact with the outer wall, crystal nucleation does not occur except on the seed crystal. In this way, reproducible seeding is possible. Since the growth interface is located in the temperature gradient region on the upper side of the high temperature portion as shown in the figure, the single crystal 9 is continuously grown by pulling the ampoule 3 upward by the driving unit 10.

Next, examples will be described in detail. The seed crystal used is 4 mm square and the orientation is <111>. This was fixed to the AlN block 15 with an AlN pin. Ampoule 3 has phosphorus (P) 11 about 50g, In
A quartz crucible 14 containing 100 to 200 g, a quartz pipe partition wall 13, and an AlN block 15 having the seed crystal 6 fixed thereon were placed in this order. Then, it was connected to a vacuum apparatus and a vacuum of 2 × 10 ⁻⁶ Torr was drawn, the upper part of the quartz pipe partition wall 13 was fused to the ampoule 3, and the ampoule was vacuum sealed. The temperature was set so that the contact surface between the seed crystal and the solution was 1000 ° C, and the temperature gradient before and after that was 10 to 30 ° C / cm. The temperature of the bottom of the ampoule was 430 ° C at which the phosphorus vapor pressure was about 2 atm. After loading the ampoule in the furnace, the temperature was raised while rotating at 4 rpm. After reaching the predetermined temperature, the temperature was maintained for about 20 hours in order to prepare a saturated solution of In-P. After that, the ampoule was pulled up at a speed of 2 to 8 mm / day. As a result, a single crystal with a length of about 5 cm was obtained.

FIG. 2 is a second embodiment of the present invention applied to the growth of an InP single crystal. (A) In the figure, 1 is a high temperature furnace, 2 is a low temperature furnace, 6 is a seed crystal, 9 is a single crystal, 11 is phosphorus, 12 is a solution of indium and phosphorus, 14 is a quartz crucible, 15 is a heat sink, and 16 is quartz. This is a jig that also serves as a partition pipe made of metal and a fixing base for the heat sink 15. The heat sink 15 is fixed by the protrusions of 17. Reference numeral 18 is a quartz container for containing phosphorus (P) 11. (B) The figure shows the temperature distribution.

In this example, the low temperature furnace 2 was placed on the high temperature furnace 1. This allows you to use a long heat sink 15,
The latent heat during crystallization could be released efficiently.
This enabled seeding with even better reproducibility.

FIG. 3 shows a third embodiment of the present invention, which is applied to InP single crystal growth. Here, the aim is to obtain a longer single crystal. (A) In the figure, 1 is a high temperature furnace, 2 is a low temperature furnace, 6 is a seed crystal, 9 is a single crystal, 10 is a driving unit, 11 is phosphorus, 12 is a solution of phosphorus and indium, 15 is a heat sink, and 17 is a protrusion. , 18 is a quartz container, 19
Is a jig that doubles as a partition pipe made of quartz and a fixing base for the heat sink 15, and has a turnback 19a. The heat sink 15 is fixed by the protrusions of 17. 20 is BN with good thermal conductivity or
It is a crucible made of AlN. Reference numeral 18 is a quartz container for containing phosphorus (P) 11. In order to obtain a long crystal, In for supplying phosphorus (P) surrounded by the crucible 20 and the quartz jig 19 is used.
It is necessary to prevent the temperature of the -P solution layer 21 from decreasing. When the temperature of the solution layer is drastically lowered, the solubility of phosphorus (P) in the In solution is remarkably reduced, and the growth rate of the crystal is lowered. In some cases, the In-P solution layer 21 is solidified to grow a single crystal. Becomes difficult to maintain.

In this embodiment, this problem could be solved by using the following three methods together.

(A) Use of a long heat sink, (b) A void 22 is provided between the quartz jig 19 and the crucible 20, and the outside and inside of the crucible of the solution layer are completely thermally separated. (C) A BN (or AlN) crucible with good thermal conductivity was used. This prevented a decrease in the temperature of the solution layer 21 above the crucible.

By combining the methods of (a), (b), and (c), a sufficient temperature difference is created between the center of the crucible (solid line) and the solution layer 21 (broken line), as shown in the temperature distribution in (b). I was able to.
As a result, even in the crystal growth for a long time, the solution layer 21
It was possible to quickly release latent heat while maintaining a high temperature, and to obtain a long InP single crystal of 10 cm or more with good reproducibility.

(Effects of the Invention) As described above, according to the present invention, a single crystal can be grown directly from the constituent elements of the compound semiconductor, so that highly pure single crystal can be grown with good reproducibility.

Further, there is an advantage that a crystal with a low dislocation density can be obtained because the stress of the crucible wall or the like is not applied during the solidification of the crystal. The present invention is most suitable for growing a compound semiconductor single crystal such as InP, GaP, and GaAs.

[Brief description of drawings]

1 (a) and 1 (b) are schematic cross-sectional views and temperature distributions of one embodiment of the apparatus used in the solution growth method for a compound semiconductor single crystal of the present invention, and FIGS. 2 (a) and 2 (b), respectively. ) And the third
FIGS. 4 (a) and 4 (b) respectively show a schematic sectional view and temperature distribution of the apparatus of another embodiment of the present invention, and FIG. 4 shows a schematic sectional view and temperature distribution of the conventional apparatus. 1 ... High temperature furnace 2 ... Low temperature furnace 3 ... Quartz ampoule 4 ... Crucible cylinder 5 ... Heat sink 6 ... Seed crystal 7 ... Second constituent element of compound 8 ... First element of compound as solvent Solution of 1st element and 2nd element 9 …… Compound semiconductor single crystal 10 …… Driving unit 11 …… Phosphorus 12 …… Sodium of indium and phosphorus 13 …… Quartz pipe partition 14 …… Quartz crucible 15 …… AlN Or BN block (heat sink) 16 …… Quartz jig 17 …… Protrusion 18 …… Phosphorus storage quartz container 19 …… Folded quartz jig 20 …… BN or AlN crucible 21 …… Crucible 18 and quartz jig 16 Outer In-P surrounded by and
Solution layer 22 ... void

Claims (2)

[Claims] 1. An ampoule, a crucible arranged in the ampoule with a gap between the ampoule, and an crucible inserted from the opening side of the crucible and arranged with a gap between the crucible. Pipe partition wall, a fixing jig for fixing the upper part of the seed crystal arranged in the pipe partition wall, a heat sink arranged on the upper part of the seed crystal for radiating heat to the upper part, and other than the crucible. The raw material storage unit and the outer periphery of the ampoule are arranged to generate a temperature distribution in the tube direction of the ampoule. The raw material storage unit has a temperature sufficient to evaporate the raw material stored therein, and the crucible part has A furnace for maintaining a temperature at which the raw material stored in the crucible melts, and a temperature that gradually decreases from the lower side of the crucible to the heat sink and the upper side of the heat sink; and a vertical movement mechanism for the ampoule. Having A compound semiconductor crystal manufacturing apparatus according to claim. 2. An ampoule, a crucible made of a material having a high thermal conductivity, which is disposed in the ampoule with a gap between the ampoule, and the crucible inserted from the opening side of the crucible. And a pipe partition having a fold-back at the bottom arranged with a gap between the pipe partition, a fixing jig for fixing the upper part of the seed crystal arranged in the pipe partition, and a fixing jig arranged on the upper part of the seed crystal. And a heat sink to let the heat escape to the top,
The raw material storage section other than the crucible is arranged around the ampoule and causes a temperature distribution in the tube direction of the ampoule, and the raw material storage section has a temperature sufficient to evaporate the raw material stored in the crucible. The part is a temperature that is sufficient to melt the raw materials contained in the part, and the furnace that holds the heat sink from the bottom of the crucible to the heat sink and the heat sink is gradually lowered. A compound semiconductor crystal manufacturing apparatus having a moving mechanism.