JP2816623B2 - Single crystal manufacturing apparatus and manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for producing a single crystal by a continuous charge method.

[0002]

2. Description of the Related Art A silicon single crystal serving as a substrate of a semiconductor device is
In the case of manufacturing by the Z method, a raw material is supplied into a crucible according to the amount of the pulled single crystal, and a continuous charge method in which the single crystal is continuously pulled, and in order to reduce a change in resistivity of the single crystal due to a segregation phenomenon, There is known a semiconductor single crystal growing apparatus which combines a quartz crucible with a double structure and a double crucible method for pulling a single crystal from an inner crucible. (U
SP2892739, JP-A-61-36197)

[0003]

The conventional semiconductor single crystal manufacturing apparatus has the following problems. (1) Volatile SiO is placed on the edge of the quartz crucible and in the chamber.
x tends to accumulate. (2) The inner crucible is deformed during melting of the initial material. (3) Impurities are mixed into the single crystal growing portion, resulting in a decrease in single crystal purity. An object of the present invention is to provide a single crystal manufacturing apparatus and a manufacturing method that can focus on the above conventional problems and can obtain a high-purity single crystal by preventing the occurrence of these problems beforehand. .

[0004]

In order to achieve the above object, a single crystal manufacturing apparatus according to the present invention has a gas collecting cylinder fixed to the inside of the upper end of a hollow cylindrical inner crucible, The lower end keeps a constant gap between the melt surface and the exhaust pipe connected to the upper end of the gas collecting pipe formed between the inner circumference of the inner crucible and the outer circumference of the gas collecting cylinder. Means for raising and lowering the inner crucible, a gas collecting cylinder and an exhaust pipe fixed to the inner crucible, and providing a raw material supply pipe for supplying a raw material from the outside of the chamber with an inner periphery of the outer crucible and an outer periphery of the inner crucible. The single crystal manufacturing method according to the present invention, in the single crystal manufacturing apparatus, raises the inner crucible and the gas collecting cylinder and the exhaust pipe fixed to the inner crucible when the initial raw material is melted. Let the initial crucible fill the outer crucible When the single crystal is pulled up, the inner crucible is lowered and the lower end of the inner crucible is immersed in the melt to separate the gas phase of the single crystal pulling section from the gas phase of the raw material supply section and collect gas. The gas on the surface of the melt collected by the pipe is discharged to the outside of the chamber through the exhaust pipe.

[0005]

According to the above construction, a gas collecting cylinder is fixed to the inside of the upper end of a hollow cylindrical inner crucible which can freely move up and down, and the lower end of the gas collecting cylinder keeps a constant gap between itself and the melt surface. Along with connecting an exhaust pipe to the upper end of a gas collecting pipe formed between the inner circumference of the inner crucible and the outer circumference of the gas collecting cylinder,
Volatile SiOx present on the melt surface during single crystal growth
Together with the inert gas pulled up from the upper part of the chamber and flowing down along the single crystal, is discharged from the gas collecting pipe to the outside of the chamber via the exhaust pipe. Further, a raw material supply pipe for supplying a raw material from the outside of the chamber is disposed between the inner periphery of the outer crucible and the outer periphery of the inner crucible, and the lower end of the inner crucible is immersed in the melt when pulling a single crystal. The gas phase of the crystal growth section and the gas phase of the raw material supply section can be separated. Thereby, impurities are mixed into the single crystal growing portion, and the crucible,
It is possible to reliably prevent the deposition of SiOx on the chamber and the like.

At the time of melting the initial raw material, the inner crucible, the gas collecting cylinder and the exhaust pipe fixed to the inner crucible are raised, and the initial raw material is melted only with the outer crucible. In addition to preventing the dissolution, the dissolution efficiency of the initial raw material can be improved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a single crystal manufacturing apparatus and a manufacturing method according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a schematic structure of a first embodiment of a single crystal manufacturing apparatus according to the first and second aspects.
An outer crucible 2 in which a quartz crucible is fitted on the inner surface of a graphite crucible is provided in a chamber 1, and the outer crucible 2 is fixed to a crucible shaft 3. The inner crucible 4 is a hollow cylinder in which a quartz tube 4b is connected to a lower end of a graphite tube 4a, and is supported by a single crystal pulling shaft 5 by a wire cable (not shown) or the like. You can move. Inside the inner crucible 4, a hollow cylindrical gas collecting cylinder 6 having a taper whose upper end has a large diameter is provided, and the upper end of the inner crucible 4 and the upper end of the gas collecting cylinder 6 are in the same plane. There and inside crucible 4
The gap between the inner periphery of the gas collecting cylinder 6 and the outer periphery of the gas collecting cylinder 6 is sealed at the upper end. A gas collecting tube 7 is formed by a gap between the inner periphery of the inner crucible 4 and the outer periphery of the gas collecting tube 6. Exhaust pipes 8 communicating with the inner periphery of the inner crucible 4 are fixed to two upper ends of the inner crucible 4, and the end of the exhaust pipe 8 is close to the inner periphery of the chamber 1. As described above, the exhaust mechanism 9 is configured by the inner crucible 4, the gas collecting cylinder 6, and the exhaust pipe 8. In the present embodiment, the two exhaust pipes 8 are provided at 180 ° intervals with respect to the inner circumference of the inner crucible 4, but the present invention is not limited to this. For example, three exhaust pipes may be provided at 120 ° intervals. Good.

When the inner crucible 4 is lowered to a predetermined position with the lowering of the single crystal pulling shaft 5, a center line is provided at a position coinciding with the center line of the exhaust pipe 8 fixed to the upper end of the inner crucible 4. An exhaust port 10 is provided, which penetrates the side wall of the chamber 1 and is slidable in the horizontal direction. The raw material supply pipe 11 is provided in the chamber 1
Penetrates the chamber 1 from the upper outside of the outer crucible 2
Of the inner crucible and the outer periphery of the inner crucible 4. The bottom plate 1a of the chamber 1 is provided with a hole through which the crucible shaft 3 is inserted at the center, and a plurality of exhaust ports 12 are provided around the hole. In addition, 13 is a heater, 14 is a heat retaining cylinder,
Reference numeral 15 denotes a melt surface, and reference numeral 16 denotes a pulled single crystal.

Next, a method for producing a single crystal by the above-described apparatus for producing a single crystal will be described. First, the outer crucible 2 is filled with polycrystalline Si as an initial material, and the inner crucible 4, the gas collecting cylinder 6 and the exhaust pipe 8 integrally formed with the inner crucible 4 are lifted by raising the single crystal pulling shaft 5. After that, the initial raw material is melted by the heater 13.

After the melting of the initial raw materials is completed, when the inner crucible 4 is lowered to a predetermined position, the exhaust port 10 slides into the chamber 1 and the end of the exhaust pipe 8 is inserted into the exhaust port 10. At the same time, the quartz tube 4b below the inner crucible 4 is immersed in the melt. In this state, while supplying the raw material from the raw material supply pipe 11 to the gap between the inner crucible 4 and the outer crucible 2,
The single crystal 16 is pulled from the inside of the inner crucible 4. At this time, the argon gas introduced from above the chamber 1 fills the chamber 1 and rises and descends along the single crystal 16, enters the gas collecting pipe 7 from the lower end of the gas collecting pipe 7, and 8 through the exhaust port 10 to the chamber 1
Is discharged outside. Therefore, volatile SiOx existing on the melt surface 15 does not deposit on the edge of the outer crucible 2 or inside the heater 13 or the like. Further, since the lower end portion of the gas collecting cylinder 6 becomes high in temperature, SiOx does not deposit. Further, the vicinity of the lower end opening of the raw material supply pipe 11 or the outer crucible 2
The impurities existing in the vicinity of the inner and outer peripheries are discharged out of the chamber 1 through the exhaust port 12 together with the argon gas. By immersing the lower end of the inner crucible 4 in the melt as described above, the gas phase in the vicinity of the end of the raw material supply pipe 11 and the gas phase in the inner crucible 4 are separated by the inner crucible 4, so that the single crystal defect It is possible to prevent impurities from being mixed, and to obtain a more reliable semiconductor single crystal.

Further, particularly when the initial raw materials are dissolved at a high temperature,
The unsupported inner crucible 4 is retracted above the outer crucible 2 to prevent thermal deformation of the inner crucible 4 and to prevent a decrease in heat transfer efficiency to the initial raw material due to the interposition of the inner crucible 4, thereby increasing the melting efficiency of the initial raw material. In addition, the time required for dissolution is reduced.

FIG. 2 is a sectional view showing a second embodiment of the present invention. The lower end of a rod 17 vertically moving through the chamber 1 from above the outside of the chamber 1 is fixed to the exhaust pipe 8. The exhaust mechanism 9 including the inner crucible 4 moves up and down by raising and lowering the rod 17 by a rod elevating mechanism (not shown), and when it is lowered to a predetermined position, the terminal of the exhaust pipe 8 and the exhaust port 10 are connected. Other structures and functions are the same as those of the first embodiment.

FIG. 3 shows a third embodiment of the present invention. An air conducting hole 18 penetrating in the vertical direction is provided in the heat retaining cylinder 14 provided so as to surround the heater 13, and an exhaust port 19 communicating with the air conducting hole 18 is attached to the bottom plate 1 a of the chamber 1. I have. The end portion of the exhaust pipe 8 communicating with the gas collecting pipe 7 is bent downward at the upper end opening of the air guide hole 18, and when the exhaust mechanism 9 including the inner crucible 4 is lowered to a predetermined position, the exhaust pipe 8 is closed. Is inserted into the upper end opening of the air guide hole 18. Volatile Si existing on the melt surface 15
Ox is discharged to the outside from the exhaust port 19 through the exhaust pipe 8 and the air conduction hole 18. Other structures and functions are the same as those of the first embodiment.

FIG. 4 shows a fourth embodiment of the present invention, in which an exhaust mechanism 9 including an inner crucible 4 can be moved up and down by a rod 17. The structure and function of this embodiment are the same as those of the third embodiment.

[0015]

As described above, according to the present invention, a gas collecting cylinder is fixed to the inside of the upper end of a hollow cylindrical inner crucible which can freely move up and down, and the inner periphery of the inner crucible and the outer periphery of the gas collecting cylinder are fixed. The volatile SiOx is introduced into a gas collecting pipe formed between the outer crucible and the exhaust pipe, and the raw material is supplied between the inner circumference of the outer crucible and the outer circumference of the inner crucible. By disposing the pipe, the gas phase of the single crystal growing section and the gas phase of the raw material supply section were separated.
It is possible to prevent Ox from being adhered to the pulled single crystal or to prevent impurities adhering to the feed material from being mixed into the single crystal, so that a single crystal having high purity and high reliability can be obtained. Further, the deposition of SiOx on the crucible, the chamber and the like can be reliably prevented.

Since the inner crucible is raised when the initial raw material is melted, thermal deformation of the inner crucible can be prevented, and work efficiency can be improved by improving the melting efficiency of the initial raw material. Furthermore, since the melt surface is partitioned by the inner crucible during the supply of the raw material during the pulling of the single crystal, it is possible to prevent the ripples generated on the melt surface by the supply of the raw material from being propagated to the single crystal growing portion. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic structure of a single crystal manufacturing apparatus according to a first embodiment.

FIG. 2 is a sectional view showing a schematic structure of a single crystal manufacturing apparatus according to a second embodiment.

FIG. 3 is a sectional view showing a schematic structure of a single crystal manufacturing apparatus according to a third embodiment.

FIG. 4 is a sectional view showing a schematic structure of a single crystal manufacturing apparatus according to a fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chamber 2 Outer crucible 4 Inner crucible 6 Gas collection tube 7 Gas collection tube 8 Exhaust tube 11 Raw material supply tube 15 Melt surface 16 Single crystal

Continuation of front page (56) References JP-A-5-51291 (JP, A) JP-A-4-317492 (JP, A) JP-A-5-85880 (JP, A) JP-A-5-43380 (JP) JP-A-61-36197 (JP, A) JP-A-5-117075 (JP, A) JP-A-54-41280 (JP, A) JP-A-4-84362 (JP, U) (58) Field surveyed (Int.Cl. ⁶ , DB name) C30B 15/00-15/36 C30B 28/00-35/00 H01L 21/208

Claims (2)

(57) [Claims] 1. A gas collecting cylinder is fixed to the inside of an upper end of a hollow cylindrical inner crucible, and a lower end of the gas collecting cylinder keeps a constant gap with a melt surface, and the inside of the inner crucible is fixed. An exhaust pipe is connected to the upper end of a gas collecting pipe formed between the circumference and the outer circumference of the gas collecting cylinder, and the inner crucible and the gas collecting cylinder and the exhaust pipe fixed to the inner crucible are raised and lowered. A single crystal manufacturing apparatus, characterized in that a raw material supply pipe for supplying a raw material from outside the chamber is provided between the inner periphery of the outer crucible and the outer periphery of the inner crucible. 2. The single crystal production apparatus according to claim 1, wherein when the initial raw material is dissolved, the inner crucible, the gas collecting cylinder and the exhaust pipe fixed to the inner crucible are raised, and the outer raw material is filled in the outer crucible. When the single crystal is pulled up, the inner crucible is lowered and the lower end of the inner crucible is immersed in the melt to separate the gas phase of the single crystal pulling section from the gas phase of the raw material supply section and collect gas. A method for producing a single crystal, wherein a gas on a melt surface collected by a pipe is discharged to the outside of a chamber through an exhaust pipe.