JPS5841796A - Apparatus for preparation of semiconductor single crystal - Google Patents

Abstract

PURPOSE:To enable the growth of a large-sized single crystal of a compound semiconductor having controlled profile, in high reproducibility, by attaching a particular ring at the top of a crucible containing molten raw material for the preparation of single crystal by liquid capsule pulling method. CONSTITUTION:In the growth of a single crystal of a compound semiconductor having high decomposition pressure by the liquid capsule pulling method, a ring 33 is attached at the top of the quartz crucible 32 for containing molten raw material so as to cover the outer circumference of the crucible with the ring. The top face of the ring 33 is positioned below the upper end of the container 31 of the crucible 32. Since the heat dissipation from the inside of the crucible is effectively suppressed by this arrangement, the temperature of the molten liquid is maintained stably higher at the circumferential part than the central part, and at the same time, the content of the crucible is heat- insulated. Consequently, the temperature gradient in B2O3 covering the surface of the molten liquid is decreased, and the generation of crack and the increase of dislocation can be suppressed. As the temperature in the molten liquid takes a U-shaped distribution which is flat at the central part and has sharp positive gradient at the circumferential part, the diameter of the single crystal can be controlled in high stability and reproducibility.

Description

[Detailed Description of the Invention] This invention relates to an apparatus for manufacturing a compound semiconductor single crystal having a high decomposition pressure such as GaP, GaAs, InP, etc. by a liquid capsule pulling method, and is particularly capable of growing a large-sized single crystal with a controlled shape with good reproducibility. Kotonodeki Gap, GaAs,
A liquid capsule pulling method is known as a method for producing single crystals of high decomposition pressure compound semiconductors such as InP. This method will be explained using the principle diagram shown in FIG. That is, the raw material melt I and the liquid capsule B2O3 (151fd car K/heated and melted by heater 08 for 9 minutes, The liquid level of liquid I is covered by 8203 (19).The inside of the pressure vessel 0υ is vacuum replaced in advance, and then an inert gas such as N2 is introduced.When melting the raw material [
maintains the pressure inside the high-pressure container OD at a predetermined pressure to prevent decomposition and evaporation of the raw material. In this state, the seed crystal n is immersed in the rporium melt through 8203@OJ and gradually pulled up while rotating to form a single crystal θg.

By the way, when pulling under high pressure using a large liquid capsule, the thermal environment is harsh and complex, and the growth of rounded crystals is inevitable, so the development of a stable manufacturing technology is desired6.
aP has a melting point (1467° C.) and a high P decomposition pressure of about 35 atm, and is usually pulled under pressure of 50 atm or more. This causes intense thermal convection of the inert gas, causing crucible and B
Heat dissipation from the top surface of 2O3 increases. In addition, B2O3
GaP under the B2O3 coating has a high viscosity and low thermal conductivity, and the temperature gradient in B2O3 is steep.
The temperature gradient within the melt becomes smaller. A large temperature gradient in B2O3 gives a large thermal strain to the growing crystal, resulting in an increase in the occurrence of cracks and crystal defects. It is possible to reduce the temperature gradient of B2O3 by modifying the structure of the heater etc.
There are problems with the limitation of effective space within the high-pressure vessel and the maintenance of high-temperature and high-pressure strength. Generally, heat retention inside the crucible is maintained by placing the crucible below the heater or by raising the crucible wall, but in the former case, the temperature at the bottom of the crucible becomes low, and the melt from the bottom of the crucible drops. Due to solidification, etc., crystal growth is accelerated. In addition, in the latter case, heat dissipation from the top of the crucible becomes large, and the temperature distribution within the raw material melt tends to be uneven, with the temperature at the 1-inch outer periphery being lower than the temperature at the center, as shown in Figure 2 (a). There is an example of the temperature distribution.

When crystals are grown under such conditions, the following disadvantages occur. In other words, the growth of the so-called head portion from seed crystal attachment until the growing crystal reaches a predetermined size is B2O3.
Because the process proceeds inside the growing crystal, heat dissipation from the growing crystal is insufficient, and in order to grow the head part, the melt must be cooled widely. crystallizes and floats. This leads to growing crystals and inhibits single crystal growth.Also, even if you try to grow the head part to a predetermined size, when the diameter expands to a certain point, growth stops and the diameter continues to decrease. . If this decrease is suppressed by increasing the cooling rate of the melt, the growing crystal will be exposed on 8203 after the growth of the head part has finished, and this time heat dissipation will suddenly improve and rapid growth will occur. . Since the outer envelope is supercooled due to the growth of the head, it is extremely difficult to control the diameter due to this rapid growth.

It is difficult to return to a constant diameter once it has fluctuated greatly. In the case of increasing the size of the charge or the diameter, the above-mentioned problems become more and more noticeable because it becomes difficult to control temperature distribution conditions and heating conditions.

Therefore, rounding that enables the reproducible growth of large single crystals with a controlled shape requires controlling the temperature distribution conditions, that is, reducing the temperature gradient in the 8203 at a sufficiently high crucible position to prevent solidification of the melt from the bottom. It is necessary to optimize the temperature distribution inside the liquid.

The first step in optimizing the temperature distribution of the melt is to make the temperature of the outer part higher than that in the center, and the second step is to control the distribution characteristics.

The present invention has been made based on the above circumstances, and is directed to the production of a semiconductor single crystal in which the degree distribution conditions necessary for growing a large compound semiconductor single crystal with a controlled shape with good reproducibility can be easily controlled. This is to clean the equipment.

That is, this invention grows a single bond crystal of a high-decomposition-pressure compound semiconductor using a liquid capsule pulling method (in this case, a ring is provided at the upper end of the crucible for storing the raw material melt, and the outer circumference is increased, and It is characterized in that the surface is located below the upper end of the crucible holding container.

As mentioned above, by providing a ring at the upper end of the crucible that encloses the outer circumference, heat dissipation from the upper end of the crucible and the inner surface of the V-vitreous pot is largely suppressed, so that the temperature inside the melt decreases at the outer circumference. At the same time, the temperature in the center becomes stably high, and at the same time the inside of the crucible is kept warm, the temperature gradient in B2O3 is reduced, and the occurrence of cracks and increase in dislocations are also suppressed. By configuring the upper surface of the ring to be positioned below the upper end of the crucible holder 8, the after-shielding effect of the crucible holder wall becomes more pronounced, and the temperature inside the melt decreases. The distribution characteristics are flat in the center and U-shaped with a large rising slope at the outer periphery! Niro. In this U-shaped temperature distribution characteristic, there is a characteristic that the shoulder diameter of the growing crystal, that is, the diameter of the straight body formed, is determined by the inner diameter of the ring without depending on the heating control conditions. As diameter control stability. Reproducibility is obtained and now it looks like this.

The present invention will be explained in detail below with reference to the drawings.

For this explanation, specific conventional examples, Example 1, Leprosy Example 2
I will explain in this order.

[Conventional specific example]

600gr f) Charge GaP polycrystal to diameter 4
The inner diameter used to pull the 51m+ single crystal was 1. Q
QllI, IIcg of Ga in a quartz crucible with height g5in
When the P polycrystal was charged, the temperature distribution in the raw material melt was as shown in Figure 2 (Q)). The distribution was as shown in Figure fa), and as mentioned above, crystals crystallized from the inner and outer peripheries of the crucible and sudden changes in diameter occurred, making normal pulling impossible. The temperature gradient in the longitudinal direction in B2O3 was also 200'0/1 or more, which was ton greater than the ~150°C/am of 600gr←yage, and all of the crystals that were cut and pulled had cracks.

□ By moving the crucible support shaft ((9) in Figure 1) downward, the crucible and the crucible holding container are positioned downward, and the crucible and the crucible holding container are moved downward, and the crucible in the raw material melt as shown in Figure 2 (b) is moved downward. Although the temperature distribution was achieved and the increase was carried out, about 3 of the charge amount
01 At the 9th point of pulling, the melt solidified from the bottom of the crucible, making it impossible to continue pulling. Although it is possible to reduce the temperature gradient in the direction of 1 part tl
The abnormal distribution of temperature lower than that of the central part became more and more noticeable.

[Example 1] A quartz crucible with a diameter of 60 mm was placed on the upper surface of a quartz crucible with a height of 11,001 ^ which was used to charge a 600 gr GaP polycrystal and pull a single crystal with a diameter of 45 mm as shown in Figure 3. If a 1ic9 GaP polycrystal is melted by providing a quartz ring to cover the outer part of the crucible with a central hole of Achieves normal temperature distribution higher than normal temperature distribution 1-1
And the vertical direction gradient in B20m is 159'Q/c.
IrLL, (could be lower.Also quartz crucible C
33p) Alternatively, make the crucible holding container e11) longer and increase the gradient in the vertical direction in B2O3 to 120°C/cI.
Even when it was reduced to below IL, the normal vertical distribution within the melt was maintained as shown in FIG. 2(b). As a result of lifting in this condition,
It was possible to pull a desired large-diameter crystal of approximately 50III without crystallization from the outer periphery of the crucible and without any sudden change in diameter without any tardage.

In Figure 3, (a) is a cross-sectional view of the crucible, and (b) is a cross-sectional view of the crucible.
is a plan view of a quartz ring.

[Example 2] The upper end of the quartz ring covering the crucible outer enclosure provided at the upper end of the quartz crucible C31 in Fig. 4 is positioned below the upper end of the V-vitreous holding container e13 ,
゛Temperature distribution characteristics in the melt are v, as shown in Figure 5, the central part is more flat 1 (the outer periphery has a large rise and becomes U-shaped with a slope. If you pull it in this state, □ Pulling will start. There is no crystallization from the outer surrounding area of the rear crucible, and the shoulder portion, that is, the straight body portion is easily formed.

In this case, regardless of the heating control conditions such as the shoulder diameter and leaf temperature drop rate, the interval between the rise starting points at the outer periphery of the temperature distribution characteristics shown in Fig. 5 (
d) It ended up being equal to +C. Even if the melt temperature continued to decrease due to straight body growth, the crystal continued to grow at the same diameter as the shoulder diameter for a while without a rapid increase in diameter. After that, proper heating control conditions made it possible to easily pull the material to a constant diameter. In addition, by changing the center hole of the quartz ring, it is possible to change the temperature distribution characteristics in the melt (temperature distribution characteristics at the outer periphery), and by using a quartz ring with a center hole of 79 mm, it is possible to Diameter 62m, weight t950g which was impossible
It was possible to easily pull up large single crystals.

As explained above, the present invention (according to which a ring is provided at the upper end of the crucible for storing the raw material melt to cover the external part of the crucible,
In addition, by positioning the upper surface of the ring below the upper end of the crucible holding container, it is possible to easily control the temperature distribution conditions required to produce a large single crystal with a controlled shape with good reproducibility. Industry - Young fruit of Hibiscus 1d large ~
stomach. Furthermore, according to the present invention, the shoulder diameter of the pulled crystal, which has been difficult to control in the past, can be almost automatically controlled, so it is also possible to effectively utilize a predetermined diameter control method such as heavy scale removal.

In the above embodiments, GaP was used as an example, but the present invention can be similarly applied to the production of high-resolution compound semiconductor single crystals such as GaAs and InP by the liquid capsule pulling method. t
Similarly, although quartz has been cited as an example of the ring material, it goes without saying that other materials such as carbon and alumina can be selected as appropriate.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the principle of the apparatus for producing compound semiconductor monocrystalline crystals by the liquid capsule drawing method. Figure 2 is an example of the temperature distribution in the crucible diameter direction within the raw material melt, and fa) is the crystal (h) is an example of a temperature distribution that is inappropriate for crystal growth; (h) is an example of @hard distribution that allows crystal growth; FIGS. FIG. 5 is a diagram showing the gradient distribution in the crucible diameter direction within the raw material melt related to the present invention. 31 Nil crucible holder, 32: Quartz crucible, 33: Ring covering the external part of the quartz crucible. Agent: Patent Attorney Noriyuki Chika (1 person for 7 days) Figure 1 Figure 2/1. , Medium adventure promotion
, l , □ Change of heart 1.・'H--噸Ij,+,
1112. Ir, Ruime Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] When growing high decomposition pressure compound semiconductor crystals by the liquid capsule pulling method, a ring is provided at the upper end of the crucible that houses the raw material melt to increase the inner and outer surroundings of the crucible, and the upper surface of the ring is placed above the upper end of the crucible holding container. 1. A semiconductor single crystal manufacturing apparatus characterized in that the semiconductor single crystal is positioned below.