JPH04357190A - Single crystal production apparatus - Google Patents

Abstract

PURPOSE:To improve the quality of a single crystal by placing a separation plate having narrowed lower end around a single crystal keeping a prescribed gap therebetween, covering a quartz crucible with a lower plate having plural small holes and passing an inert gas through the gap between the single crystal and the separation plate. CONSTITUTION:A raw material melting part 200 is evacuated through an evacuation port and an inert gas such as Ar is introduced into the apparatus. A quartz crucible 5 is heated to melt the raw material by electrifying a heater 8 and a seed crystal is immersed in the molten raw material. The inert gas flow passing through the gap between the single crystal 1 and the separation plate 13 increases its speed at the narrowed part 2 to discharge the component evaporated from the molten liquid surface through the small holes 6 of the lower plate 7. Furthermore, the intrusion of impurities into the single crystal 1 in pull-up stage is prevented e.g. by the action of the lower plate 7 to prevent the reflux of the condensed product removed from the molten liquid surface by the inert gas. The crystal is pulled up at a prescribed speed by a pull-up part 300 to obtain a single crystal 1 free from crystal defect.

Description

[Detailed description of the invention]

[Object of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor single crystal manufacturing apparatus, and more particularly to a semiconductor single crystal manufacturing technique for manufacturing a highly pure and homogeneous semiconductor single crystal.

0003

2. Description of the Related Art A CZ (Czochralski pulling) method is used to grow semiconductor single crystals, in which a cylindrical crystal is grown from a raw material melt in a crucible. The single crystal to be grown is required to be of extremely high purity, but during pulling, lumps of silicon monoxide condensate fall into the melt in the crucible and are incorporated into the pulled single crystal as impurities. There have been problems in that the crystallization is inhibited, and single crystallization is inhibited.

[0004] Therefore, in order to solve such problems,
A flat annular rim is protruded inward from the edge of the crucible, a cover is attached to the annular rim so that it tapers into a cylindrical or conical shape, and the flow rate and pressure of inert gas are adjusted appropriately into the reactor. A method has been proposed in which the condensate or lumps condensed during pulling are prevented from falling into the melt by doing so (Japanese Patent Publication No. 57-40119 or Japanese Patent Publication No. 58-1080).

However, in such a structure, silicon monoxide condensate or lumps that are condensed during pulling adhere to the outside of the cover, that is, on the low-temperature side, and fall into the melt. The condensate that fell into the melt caused crystal defects in the growing silicon single crystal.

Furthermore, as a result of various experiments, the present inventors found that
In this way, it is incorporated into the pulled single crystal as an impurity,
We discovered that in addition to silicon monoxide condensates, there are metals, metal oxides, and other substances that cause polycrystalization.

[0007]

[Problems to be Solved by the Invention] In this conventional structure, silicon monoxide condensate or lumps, metals, metal oxides, etc. that are condensed during pulling adhere to the outside of the cover, that is, the low temperature side. This falls into the melt and causes crystal defects in the growing silicon single crystal.

The present invention has been made in view of the above-mentioned circumstances, and provides a semiconductor that can prevent impurities from being incorporated into a growing silicon single crystal and obtain a highly reliable semiconductor single crystal with few crystal defects. The purpose is to provide a single crystal manufacturing device.

[Configuration of the invention]

0010

[Means for Solving the Problems] Accordingly, in the present invention, in a semiconductor single crystal manufacturing apparatus, the entire surface above the heater and crucible in the single crystal pulling device is covered, and the diameter is reduced by descending to the vicinity of the solid-liquid interface in the single crystal pulling region. and a separator that forms an opening between the single crystal in the pulling region and divides the gas phase in the single crystal manufacturing apparatus into two by leaving this opening, and the inside of this separator (downward). ), a lower plate is arranged to cover the upper part of the crucible like a lid and has a plurality of small holes, and an inert gas is flowed between the separator plate and the single crystal, and the lower plate It is made to be discharged through a small hole provided in the.

In the second aspect of the present invention, an inner cylinder that surrounds the pulled single crystal and whose diameter decreases toward the bottom; an upper plate that is connected to the upper end of the inner cylinder and covers the entire upper surface of the crucible and the heater; A separator plate consisting of an outer cylinder attached to the outer periphery, and a lower plate that is located inside (below) this separator plate and covers the raw material melt in the crucible like a lid and has a plurality of small holes are provided. An inert gas is caused to flow between the separator and the single crystal in the direction of the raw material melt.

Preferably, the distance between the cylinder and the single crystal is 20 mm, and the diameter is reduced to about 10 mm at the lower end of the cylinder.

Furthermore, it is preferable that a conical or truncated conical tube whose diameter decreases upward and is open at the tip is attached to the small hole.

[0014]

[Function] According to the above structure, since the plate-shaped body is provided with a plurality of small holes at a predetermined interval around the single crystal being pulled, the evaporated matter is condensed and the raw material is melted. It can prevent it from falling into the liquid.

On the other hand, since the diameter of the lower end of this cylinder is reduced to reduce the distance between it and the single crystal being pulled,
On the other hand, the flow rate of inert gas increases in the boundary region between the single crystal and the dissolved silicon during pulling, and even if the raw material melt contains a small amount of impurities, gaseous impurities will adhere to the single crystal during pulling. is prevented.

[0016] Furthermore, this gap between the cylinder and the single crystal is necessary for the radiant heat to be efficiently removed from the high-temperature single crystal that has just been pulled from the melt, and the lower limit of this gap is approximately 20 mm. It is.

[0017] Furthermore, by attaching a conical or truncated conical cylinder whose diameter decreases upward and is open at the tip to the small hole, it is possible to prevent the generated condensate from falling into the melt. Can be done.

[0018]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment 1 A single crystal manufacturing apparatus according to a first embodiment of the present invention is as shown in FIGS. 1 and 2 (FIG. 1 is a sectional view and FIG. 2 is a perspective view of the lower plate). It is composed of a crystal manufacturing apparatus main body 100, a raw material melt section 200 provided inside the main body 100, and a pulling section 300. Then, a cylindrical inner cylinder 3 surrounds the pulling part 300 and has a reduced diameter part 2 such that the distance from the pulled single crystal 1 at the lower end is about 10 mm;
An upper plate 4 that is connected to the upper end of the quartz crucible 5 from near the pulling part 300 and reaches between the heater 8 and the manufacturing apparatus 100 to cover the upper side; A separator 50 consisting of an outer cylinder 30 that surrounds the heater 8 and is supported by the bottom (not shown) of the manufacturing apparatus main body 100; The lower plate 7 is formed to cover the lower plate and has a small hole 6.

The reduced diameter portion 2 of the separator 50 is constructed such that the distance between the reduced diameter portions 2 of the separator plate 50 sharply decreases (l2) near the boundary with the melt. Further, this lower plate 7 is provided with a small cylinder 6s in the shape of a cone or truncated cone whose diameter decreases upward in each of the small holes 6 and whose tip is open, so that the generated condensate can be melted. It has a structure that prevents it from falling into the liquid. Note that the distance between the separator 3 and the single crystal 1 is l1 at the top.
= 20 mm, and l2 = 10 mm at the lower end. Further, side holes 7h are formed on the sides of the lower plate 7.

Furthermore, a heater 8 is provided between the quartz crucible 5 and the upper plate 4 to maintain the temperature of the quartz crucible at a predetermined value.

From above this separator 50, a supply port O1 arranged above the single crystal manufacturing apparatus main body 100 can be seen.
Argon gas is supplied through the chamber and exhausted through an exhaust port (not shown) disposed below.

Therefore, the argon gas flows between the inner cylinder 3 of the separator plate and the pulled single crystal 1, rapidly increases the flow velocity in the diameter-reduced section 2, and removes volatile matter (silicon oxide, silicon oxide, etc.) from the raw material melt. metal oxide) and small holes 6 provided in the lower plate 7.
, flows along the inside of the heater 8 and the outer cylinder 30, and is finally exhausted to the outside of the system.

Further, the condensate generated in the single crystal production apparatus is discharged through the space between the lower plate 7 and the upper plate 4, and the lower plate 7 is connected to each small hole 6. small tube 6s
Therefore, even if it adheres to the inner wall of the upper plate 4, it will not be contained in the raw material melt due to the presence of the conical or truncated conical small cylinder 6s whose diameter decreases upward and the tip is open. It almost never falls.

The lower plate 7 and the separator 50 are made of thermally stable materials such as quartz and carbon.

In addition, the raw material melt section 200 further includes a quartz crucible 5 mounted in the graphite crucible 11 supported by a crucible holder 10 mounted on a pedestal (crucible support stand) 9 within the heater 8. The silicon raw material is melted inside the crucible 5 and held as a raw material melt.

Furthermore, the pulling section 300 grows the single crystal 1 by immersing a seed crystal in this raw material melt and pulling it up at a predetermined speed.

Next, a method for growing a silicon single crystal using the single crystal manufacturing apparatus shown in FIG. 1 will be described.

First, the exhaust port is evacuated, and the raw material melt part 2
00 is a reduced pressure state.

Then, the heater 8 for heating the inside of the quartz crucible 5 is turned on to obtain a raw material melt, and the seed crystal is immersed in the raw material melt and pulled up at a predetermined speed by the pulling unit 300. Grow single crystal 1.

The conditions for single crystal growth are as follows: quartz crucible 4 has a diameter of 16 inches, the amount of melt in the quartz crucible 3 is 15 kg, the grown single crystal 1 has a diameter of 4 inches, and the resistivity (phosphorus dope) is 15 Ω.
・cm, pulling speed 1mm/min. It is.

As described above, according to the device of the present invention, by adopting the configuration including the separator plate 50 and the lower plate 7,
Since the flow of inert gas introduced into the device is maximum near the solid-liquid interface (near the boundary between the single crystal being pulled and the melt), volatile matter from the melt surface is quickly carried away. is,
Impurities can be prevented from being incorporated into the single crystal during pulling.

Further, the lower plate 7 provided above the melt is
The inert gas prevents backflow of condensate removed from the melt surface.

Furthermore, as described above, since the small tube 6s is provided in the small hole 6, even if the generated condensate falls, the probability that it will return to the melt is greatly reduced.

[0035] Therefore, while the conventional CZ method involves contamination with impurities, the contamination of impurities is significantly reduced in the single crystal grown using the present invention.

In the apparatus of the present invention, quartz or carbon is preferable as the material for the parts near the melt, but it is particularly desirable to use high-purity quartz for the parts that come into contact with the melt.

In the above embodiment, the small holes are arranged in an arc, but as shown in a modification shown in FIG. 3, holes with a circular cross section may be arranged at a predetermined density. Further, the small tube attached to the small hole may be omitted.

Furthermore, in the above embodiment, the lower end of the inner cylinder 3 of the separator 50 is formed with a diameter-reduced portion perpendicular to the axial direction, and the distance from the single crystal near the solid-liquid interface is rapidly reduced. However, as shown in FIG. 4 as a separator 51, it may have a tapered shape in which the distance from the single crystal gradually decreases.

Furthermore, the present invention is not limited to the above embodiments, but can be applied to various applications, such as the growth of single crystals other than silicon, the application of a magnetic field, and the use of granular raw materials.

[0040]

Effects of the Invention As explained above, according to the present invention, the crystals are arranged around the single crystal being pulled at a predetermined interval, and the diameter of the lower end is reduced so as to be connected to the single crystal being pulled. It is equipped with a separator plate with a small interval and a lower plate with a plurality of small holes arranged at a predetermined height so as to cover the raw material melt in the crucible. The flow rate of the inert gas at the solid-liquid interface between the crystal and the melt increases, allowing gaseous impurities to be quickly carried away from the melt surface and preventing backflow. It is possible to prevent the adhesion of particles and to efficiently obtain a high-quality semiconductor single crystal with high purity and no defects.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a single crystal growth apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view of the lower plate of the single crystal growth apparatus.

FIG. 3 is a diagram showing a modification of the lower plate of the present invention.

FIG. 4 is a diagram showing a single crystal growth apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

100 Single crystal manufacturing equipment main body 200 Raw material melt section 300 Pulling part 1 Pulled single crystal 2 Reduced diameter part 3 Inner cylinder 4 Upper board 5 Quartz crucible 6 Small hole 6S small hole 7 Lower plate 8 Heater 9 Pedestal (crucible support stand) 10 Crucible holder 11 Graphite crucible 13 Separation plate 30 Outer cylinder 50 Separation plate 51 Separation plate

Claims (3)

[Claims] 1. A crucible filled with a raw material melt; a heating heater disposed around the crucible to melt the raw material in the crucible to form a raw material melt; In a single crystal manufacturing apparatus equipped with a pulling mechanism that immerses the crystal and pulls the single crystal, it covers the heater and the upper part of the crucible, descends toward the center of the crucible, reaches near the solid-liquid interface, and reaches the lower end. a separator whose diameter is reduced by about 100 mm to form an opening between the single crystal in the pulling region and leave this opening to divide the gas phase portion in the single crystal manufacturing apparatus into two;
A lower plate is disposed at a certain height from the surface of the raw material melt in the separator so as to cover the upper part of the quartz crucible in a lid-like manner, and has a plurality of small holes, and the separator and the single 1. An apparatus for producing a single crystal, characterized in that an inert gas is passed between the crystal and the crystal and is discharged through a small hole provided in the lower plate. 2. The single crystal according to claim 1, wherein the small hole has a conical or truncated conical tube whose diameter decreases upward and whose tip is open. Manufacturing equipment. 3. A crucible filled with a raw material melt; a heater disposed around the crucible to melt the raw material in the crucible to form a raw material melt; In a single crystal manufacturing apparatus equipped with a pulling mechanism for dipping the crystal and pulling the single crystal, the single crystal is disposed at a predetermined interval around the single crystal in the pulling region, the lower end is reduced in diameter, and the a separator consisting of an inner cylinder with a small distance from the single crystal, an upper plate that covers the crucible and above the heater, and an outer cylinder installed around the outer periphery of the upper plate; a lower plate disposed at a predetermined height of the upper plate so as to cover the liquid and having a plurality of small holes;
A single crystal manufacturing apparatus characterized in that an inert gas is caused to flow between the cylinder and the single crystal and is discharged through the small hole.