JPS62105992A - Apparatus for producing semiconductor single crystal - Google Patents

Abstract

PURPOSE:To enable the continuous production of a semiconductor single crystal having uniform and high electrical resistivity along radial and longitudinal directions, by using a heat-insulation cylinder and dividing a molten semiconductor reservoir with said cylinder into raw material rod melting part under a semiconductor raw material rod and a semiconductor single crystal growing part. CONSTITUTION:A semiconductor raw material rod 9 is lowered from a feeding furnace 8 of a charging chamber furnished with a gate valve 14, heated with a high-frequency preheating coil 10 and melted in a quartz crucible 4 furnished with a heater 2. A semiconductor single crystal 7 is grown in a semiconductor growing part 12 of a molten semiconductor 5 produced by the above process and pulled up into a growing furnace 6. In the semiconductor single crystal production apparatus having the above construction, the molten semiconductor reservoir 5 is divided with a heat-insulation cylinder 13 into a raw material rod melting part 11 under a semiconductor raw material rod 9 and a semiconductor single crystal growing part 12 under the semiconductor single crystal 7. The propagation of the temperature fluctuation in the raw material rod melting part 11 and the flow disturbance of the molten semiconductor to the semiconductor single crystal growing part 12 can be inhibited by this process to enable the production of a semiconductor single crystal 7 having excellent quality.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an apparatus for manufacturing semiconductor single crystals, and particularly to an apparatus for continuously manufacturing high quality semiconductor single crystals with excellent homogeneity. be.

[Conventional technology]

In recent years, the demand for single crystal semiconductors such as silicon has increased,
In order to improve productivity in device manufacturers, semiconductor single crystal manufacturing equipment has become larger, and the diameter of semiconductor single crystals that are pulled and manufactured is also rapidly increasing in size.

However, in batch-type semiconductor single crystal production equipment, due to the characteristics of the equipment, as the semiconductor single crystal is pulled up and grown, the amount of molten metal in the semiconductor molten metal pool decreases, and the amount of dopant in the molten metal pool decreases. The drawback is that the concentration of the dopant increases and the dopant segregated in the pulled and grown semiconductor single crystal gradually increases in the longitudinal direction, and as a result, the quality of the produced semiconductor single crystal deteriorates along the longitudinal direction. have.

In other words, due to the (e-folding) of the doping material, the electrical resistivity of the semiconductor single crystal gradually decreases as solidification progresses. The yield is about 40% or less of the length of the grown semiconductor single crystal.

Under such circumstances, for example, Japanese Patent Application Laid-Open No. 52-58080
, JP-A-56-164097, JP-A-56-84397
As shown in JP-A-59-79000, a method was proposed in which a raw material rod made of a polycrystalline semiconductor was continuously supplied to a molten metal pool to suppress the deterioration in quality of the semiconductor single crystal as it grew. has been done.

[Problem that the invention seeks to solve]

However, the former two methods require a crucible for dissolving raw materials,
This requires a pulling crucible, making the structure extremely complex, and there are also problems in that the controllability of supplying the molten metal at a minute flow rate is poor. Furthermore, the latter two methods have the problem that the crucible cannot be rotated because of the lack of axial symmetry, making it difficult to obtain a homogeneous semiconductor single crystal. Furthermore, in the last method, since the raw material is directly immersed in the molten metal pool, the rotation of the crucible generates a complicated flow of the molten metal, which greatly impairs the uniformity of quality within the crystal cross section. Furthermore, since the crucible heater is the only heat source for melting the raw materials, it must be heated to a relatively high temperature in proportion to the heating temperature in the batch method.
The temperature gradient in the radial direction inside the crucible becomes large, and the isothermal curve at the crystal growth interface deviates significantly from a straight line parallel to the opposite surface, causing non-uniformity in the crystal growth rate in the radial direction.
Therefore, there is a problem that it becomes difficult to maintain uniformity of quality in the radial direction.

The present invention was made to solve these problems, and aims to provide an apparatus that can continuously manufacture semiconductor single crystals having high and uniform electrical resistivity in both the radial and longitudinal directions. The purpose is to

[Means for solving problems]

A semiconductor single crystal manufacturing apparatus according to the present invention is a semiconductor single crystal manufacturing apparatus in which a molten semiconductor is pulled up little by little from a pool of molten semiconductor, solidified and grown into a columnar shape, and thereby a semiconductor single crystal is obtained. The above raw material semiconductor loading chamber, a gate pulp for hermetically isolating the raw material semiconductor loading chamber, a raw material rod made of polycrystalline semiconductor loaded in the raw material semiconductor loading chamber, and a high-frequency induction preheating coil for preheating the raw material rod. , a heat insulating cylinder that divides the molten metal pool into a raw material rod melting section below the raw material rod and a semiconductor single crystal growth section below the semiconductor single crystal.

[Effect]

In this invention, since a heat insulating cylinder is provided which divides the molten metal pool into the raw material rod melting section below the raw material rod and the semiconductor single crystal growth section below the semiconductor single crystal, the effect on the semiconductor single crystal growth section is reduced. The effects of temperature fluctuations in the raw material rod melting section and disturbances in the flow of the molten metal are avoided.

〔Example〕

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, and the second t! l
t is a view from ■-■ arrow in Figure 1, in which (1) is a carbon crucible, (2) is a heater surrounding this carbon crucible, (3) is a heat insulating material surrounding this heater,
(4) is a quartz crucible covering the inside of the carbon crucible (11), (5) is a semiconductor molten metal pond held in this quartz crucible, (6) is a semiconductor single crystal growth furnace provided above this semiconductor molten metal pond, (7) is a columnar semiconductor single crystal body that is gradually pulled up from the molten semiconductor pool (5) little by little and solidified in the lower part of this semiconductor single crystal growth furnace; (8)
are a pair of raw material semiconductor supply furnaces provided adjacent to the semiconductor single crystal growth furnace (6); (9) and (9) are raw material rods made of polycrystalline semiconductors suspended in the raw material semiconductor supply furnace; (
country, (10) is a high-frequency induction preheating coil that preheats this raw material rod, (Ill is a raw material rod (9) in the molten metal pool (5), (9)
The lower part of the raw material melting part (f12) is the semiconductor single crystal (
7) Semiconductor single crystal growth section located in the lower part of (13)
(14) and (14) are gate pulps that hermetically isolate the raw material semiconductor supply furnace (8) from the others. The heat insulating cylinder (131) is a semiconductor single crystal growth section (1
It is installed for the purpose of preventing it from affecting the environment.

The heat insulating cylinder (131) has a double cylinder structure made of quartz filled with a heat insulating material, and is fixed to the upper part of the chamber (fixing jig is not shown).

FIG. 3 shows the effect of using a heat insulating cylinder fl:11.

When a heat insulating cylinder (++3) is used, the temperature distribution A in the molten metal pool (5) is different from the temperature distribution A in the melt pool (5) in the raw material melting section (11), compared to the case B when the heat insulating cylinder (1 heat) is not used. Furthermore, in the semiconductor single crystal growth section (No. 1), an isothermal curve close to the liquid level is obtained, creating an extremely favorable environment for the growth of semiconductor single crystals.

Note that the structure of the heat insulating cylinder (131) may be a double quartz cylinder whose inside is reinforced with a high melting point metal such as a molybdenum plate, and the inside of which is evacuated.

High frequency induction preheating coil (1..., (country) raw material rod (9),
Control means for preheating (9) to a temperature in the range of 1100°C to 1400°C and controlling the supplied current so that the liquid level (2) in the molten metal pond (5) is always constant within a depth range of 2 to 7 cm. It is equipped with Furthermore, high frequency induction preheating coil f1111, (l
O) is switched to a 500KHz, 50KW power supply (not shown) and connected to FjThQ.

Experimental example A molten silicone metal (5) is held in a crucible with a diameter of 25 inches, and inside the molten silicone, an inner diameter of 12 inches and an outer diameter of 1.
A 3 inch, 5 cm long insulated cylinder (++l is immersed for 3 cm, and the dope material is contained in the Noricon melt (5)).
Melt the raw material rod (9) with an inch diameter, and melt the Noricon molten metal (5
), a silicon semiconductor single crystal (7) with a diameter of 6 inches and a length of 2 m was grown. The procedure involves using approximately 30 kg of molten silicon (5) containing the doping material (at a depth of 5
cm) at a predetermined temperature, and in that state, the raw material rods (9), (
The vicinity of the tip of the raw material rod (9) is heated to approximately 850°C by the radiant heat of the molten metal pool (5), and current is applied from the high frequency power source to the high frequency induction preheating coil f101.
The tip of the was preheated to about 1300°C. Note that the supplied raw material rod (9) was rotated at 5 rpm for the purpose of uniformly melting it. Although it is desirable that the depth of the molten metal pool (5) be shallow in order to prevent large heat convection, the depth was set to 5 cm in this experimental example from the viewpoint of temperature uniformity and dope uniformity.

While the seed crystal is immersed and the necking operation is being performed, the preheated raw material rod (9) is immersed into the molten metal pond (5) and melted, and from then on the liquid level position is always at the fixed position. The preheating temperature and feed rate of raw materials were controlled as follows. As a result, we were able to pull a high-quality semiconductor single crystal with excellent homogeneity and no dislocation, similar to the conventional batch-type semiconductor single crystal growth.

In addition, when one raw material rod (9) is consumed to a predetermined amount, the other raw material rod (9) that has been loaded in advance is supplied, and in the meantime, the gate pulp f141, (the group is closed and the exhausted raw material rod ( By repeating this operation of replacing 9) with a new raw material rod (9), it becomes possible to continuously grow semiconductor single crystals and continuously manufacture long semiconductor single crystals.

Other crystal growth conditions were: the semiconductor single crystal (force rotation speed was 15 rpm, the crucible rotation speed was 3 rpm in the opposite direction, and the pulling speed of the semiconductor single crystal (7) was 3 rpm in the constant diameter section). .0 mm/min.

In addition, in this experimental example, the liquid level position was controlled by the feed rate of the raw material rod (9), so there was no need to raise the crucible, but the crucible was moved up and down to finely adjust the liquid surface. You may do so. However, in this case, there is a possibility that the concentration of the dopant in the molten metal may slightly fluctuate from a steady state.

Next, FIG. 4 shows the resistivity distribution of the semiconductor single crystal obtained in this experimental example. As can be seen from this figure, the resistivity distribution in the direction (corresponding to the crystal length and solidification fraction) is higher than that of the conventional patch method (151). rate distribution (1ω, the variation rate is within 1% over the entire length of the crystal, and C-MO3
When considering commercial wafers, the yield is about 40% compared to the conventional one.
- A yield of nearly 100% can be obtained.

It goes without saying that from the viewpoint of the growth and quality of the semiconductor single crystal, a magnetic field applying device may be added to the configuration of the present invention for the purpose of preventing the silicon melt from flowing.

〔Effect of the invention〕

As explained above, this invention prevents temperature fluctuations in the raw material melting part and disturbances in the flow of the molten metal from affecting the semiconductor single crystal growth part, so that it has a homogeneous tS electrical resistivity in both the radial direction and the length direction. This has the effect that semiconductor stopped crystals can be manufactured continuously.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing one embodiment of the present invention, Fig. 2 is a view from the ■-■ arrow in Fig. 1, Fig. 3 is a graph showing the temperature distribution in the crucible, and Fig. 4 is a solidification fraction. It is a graph showing the relationship between and electrical resistivity. In the figure, (11 is a carbon crucible, (2) is a heater, (3) is a heat insulator, (4) is a quartz crucible, (5) is a semiconductor molten metal pool, (6) is a semiconductor single crystal growth furnace, (7) is a semiconductor single crystal, (8) is a raw material semiconductor supply furnace, (9) is a raw material rod, DI is a high-frequency preheating coil, (11) is a raw material rod melting section, (14 is a single crystal growth section, (+31 is a heat insulating cylinder, (14
1 is gate pulp. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] A semiconductor single crystal manufacturing apparatus for obtaining a semiconductor single crystal by pulling up a molten semiconductor little by little from a pool of molten semiconductor and solidifying and growing it into a columnar shape, which comprises at least one raw material semiconductor loading chamber and the raw material semiconductor loading chamber. A gate pulp that seals and isolates the chamber, a raw material rod made of polycrystalline semiconductor loaded in the raw material semiconductor loading chamber, a high frequency induction preheating coil that preheats the raw material rod, and a molten metal pool that connects the raw material below the raw material rod. 1. An apparatus for manufacturing a semiconductor single crystal, comprising: a heat insulating cylinder partitioned into a rod melting section and a single crystal growth section below the semiconductor single crystal.