JPH06279168A - Single crystal manufacturing equipment - Google Patents

Abstract

(57) [Summary] [Purpose] The quality of single crystals is prevented from deteriorating due to displacement of the melt interface or crucible position accompanying the progress of single crystal growth, and high quality and homogeneous single crystals are produced with good growth rate. To do. [Structure] In a single crystal manufacturing apparatus used for pulling a single crystal ingot while growing it from a melt in a crucible,
When arranging a heat shield consisting of a substantially conical tubular body that surrounds the growing single crystal ingot coaxially and has its lower end close to the outer peripheral surface of the single crystal ingot, as the support, the upper outer periphery of the heat shield A lifting mechanism that is connected to the surface and supported from below on the side of the crucible is used.Furthermore, the thermal shield is displaced by the lifting mechanism in relation to the fluctuation of the melt interface accompanying the growth of the single crystal ingot. A control means is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing a single crystal used for producing a single crystal ingot of silicon or the like, and in particular, improvement of an apparatus configuration having a heat shield for blocking radiant heat from a melt. It is about.

[0002]

2. Description of the Related Art As a method for producing a single crystal such as silicon,
The Czochralski method (CZ method), in which crystals are pulled from a melt in a crucible while growing, is widely used. This CZ
In an apparatus used for manufacturing a silicon single crystal by the method, a heat shield having an inverted conical tubular body whose lower end is close to the silicon single crystal and the melt with the silicon single crystal being pulled as an axis is provided ( For example, Japanese Patent Publication No. 57-40
119 and JP-A-62-138386) have been proposed. FIG. 3 is a use state diagram showing a configuration of a single crystal manufacturing apparatus in which such an inverted conical heat shield is arranged.

A single crystal manufacturing apparatus 31 shown in FIG. 3 has a chamber 2 consisting of a heating chamber section 2a and a pulling chamber section 2b. Inside the heating chamber portion 2a, a quartz crucible 4 supported by a rotary shaft 3 extending through a chamber bottom portion by a driving device (not shown) located outside the chamber 2 is arranged. A cylindrical heater 5 surrounding the crucible 4 with a predetermined space is provided,
Further, a heat insulating material 6 is arranged outside the heater 5. In this example, the outer circumference of the quartz crucible 4 is protected by a graphite crucible 7, and the graphite crucible 7 is supported by the rotary shaft 5 via a graphite tray 8.

Above the quartz crucible 4, a single crystal ingot 10 pulled up from the silicon melt 9 formed in the quartz crucible 4 is coaxially surrounded, and its lower end portion is at the interface of the melt 9 and the single crystal ingot 10. A heat shield 17 composed of an inverted conical tube is arranged near the outer peripheral surface of the crystal ingot 10, and the heat shield 17 is extended above the upper end of the heat insulator 7 on the outer peripheral surface of the upper end thereof. It is supported by being connected to the fixed support 18.

On the other hand, the pulling chamber portion 2b is extended above the heating chamber portion 2a along the pulling axis of the single crystal ingot 10 pulled from the silicon melt 9 formed in the quartz crucible 4. The inner diameter is smaller than that of the heating chamber portion 2a.

Further, a pulling wire 14 having a chuck 13 for holding the seed crystal 12 at a tip portion penetrating from the upper wall surface of the chamber and hanging from above is arranged in the chamber 2, and the pulling wire 14 is The wire pulling device 11 provided on the upper portion of the pulling chamber portion 2b enables the lifting and lowering while rotating.

In the manufacturing apparatus 31 having such a structure, in order to grow a single crystal, first, the quartz crucible 4 is charged with a predetermined amount of raw materials such as polycrystalline silicon and a dopant added as necessary. The raw material is melted by heating with the heater 5 to form the melt 9. Then, the seed crystal 1 attached to the melt 9 at the tip of the pulling wire 14
2 is soaked, the quartz crucible 4 and the seed crystal 12 are pulled up while being rotated, and the single crystal ingot 1 is attached to the lower end of the seed crystal 12.
It grows 0. During the single crystal pulling operation, the inert gas is introduced into the chamber 2 through the inert gas inlet 15 provided in the pulling chamber portion 2b and flows down from the pulling chamber portion 2b to the heating chamber portion 2a. A gas flow is formed. Also chamber 2
The gas inside is exhausted to the outside of the system by being sucked by an exhaust device (not shown) communicating with the gas exhaust port 16 provided on the bottom surface of the heating chamber 2a.

In the single crystal pulling apparatus 31 having such a structure, since the heat shield 17 having an inverted conical shape is arranged above the quartz crucible 9 as described above, the heater 5 and the melting point are melted. Single crystal ingot 1 grown from liquid 9 etc.
The radiant heat toward 0 is blocked, the cooling of the single crystal ingot 10 is promoted, and the pulling speed can be increased. Also,
The presence of the heat shield 17 effectively prevents the problem that the SiO gas generated from the melt 9 rises and solidifies and adheres to the wall surface of the chamber 2 and drops to the single crystal growth interface to cause dislocation. It is something.

[0009]

When the single crystal ingot 10 is pulled up using the single crystal manufacturing apparatus as shown in FIG. 3, the amount of the melt 9 decreases as the growth of the single crystal ingot 10 progresses. To do. On the other hand, since the heat shield 17 is fixedly supported as described above, and its position is unchanged, the distance between the interface of the melt 9 and the lower end of the heat shield 17 is determined by the single crystal ingot 10. Of the single crystal growth interface, the flow of the inert gas in the vicinity of the single crystal growth interface and the amount of radiant heat to the growth interface change, making it difficult to maintain optimal conditions for obtaining the desired crystal quality. Or, the constraints for its realization became greater. Conventionally, in order to keep the interface height of the melt 9 constant, the quartz crucible 4 is also raised according to the decrease in the amount of the melt 9, but the quartz crucible 5 is raised in this way. Even in the case of allowing it, the quartz crucible 4 and the heater 5
Due to the change in the positional relationship with the above, the amount of radiant heat to the single crystal growth interface changes as described above.

Incidentally, Japanese Patent Publication No. 58-1080 discloses that
In order to facilitate the supply of the raw material to the quartz crucible 5 and to improve the efficiency at the time of melt formation, such a heat shield 10 is supported so that it can be moved up and down from above, and the heat shield is maintained until the start of single crystal growth. It has been proposed to hold the body 10 relatively upward, but in this document, the interface between the melt 9 or the quartz crucible 4 and the heat shield 10 during single crystal growth as described above. No consideration has been given to changes in the single crystal growth conditions due to changes in the physical positional relationship, and when the heat shield 10 is supported from above in this way, the support exists in the space above the heating chamber 2a. The SiO gas is solidified and adhered to this support, and this may fall to the single crystal growth interface to cause dislocation.

Therefore, according to the present invention, the quality deterioration of a single crystal due to the displacement of the melt interface or the position of the crucible accompanying the progress of the growth of the single crystal is prevented, and a high quality and homogeneous single crystal is produced with a good growth rate. It is an object of the present invention to provide an apparatus for producing a single crystal that can be manufactured. The present invention also provides an improved single crystal manufacturing apparatus capable of maintaining optimum conditions for single crystal growth throughout a pulling operation in a single crystal manufacturing apparatus having an inverted conical heat shield. It is intended.

[0012]

Means for Solving the Problems The present invention, which achieves the above objects, is an apparatus for producing a single crystal which is used for pulling a single crystal ingot while growing it from a melt in a crucible. The single crystal ingot is coaxially surrounded, the lower end of which has a heat shield consisting of a substantially conical tube body that is close to the outer peripheral surface of the single crystal ingot, and the upper end outer peripheral surface of this heat shield is connected. On the side of the crucible, a support body that supports the inverted conical tube body from below is provided with a lifting mechanism
Further, it is characterized in that it further comprises control means for displacing the heat shield by the elevating mechanism in relation to the change of the melt interface with the progress of the growth of the single crystal ingot.

[0013]

In the apparatus for producing a single crystal of the present invention, the inverted conical heat shield is supported so as to be able to move up and down from below, and is related to the fluctuation of the melt interface accompanying the progress of growth of the single crystal ingot. The heat shield can be arbitrarily displaced. For example, by lowering the heat shield as the melt interface is lowered and keeping the distance between the melt interface and the heat shield lower end constant, The amount of radiant heat to the crystal growth interface and the gas flow in the vicinity of the growth interface can be made constant by pulling up the single crystal, and high quality and homogeneous single crystal can be obtained by maintaining the optimum single crystal growth conditions. It is a thing.

[0014]

The present invention will be described in more detail based on the embodiments below. FIG. 1 is a use state diagram schematically showing the configuration of one embodiment of the silicon single crystal production of the present invention.

The single crystal manufacturing apparatus 1 shown in FIG. 1 is similar to the conventional single crystal manufacturing apparatus 31 shown in FIG. 3 in that the driving chamber (not shown) located outside the chamber 2 inside the heating chamber 2a. A quartz crucible 4 supported by a rotary shaft 3 extending through the bottom of the chamber through a graphite tray 8 and the outer periphery of which is protected by a graphite crucible 7, and the crucible 4 is surrounded by a predetermined distance. A cylindrical heating heater 5 and a cylindrical heat insulating material 6 are arranged on the outside of the heater 5, and the tip of the chamber 2 is hung from the upper side through the chamber upper wall surface. A pulling wire 14 having a chuck 13 for holding the seed crystal 12 is arranged in the portion, and the pulling wire 14 is the pulling chamber portion 2
By the wire pulling device 11 provided on the upper part of b,
It is possible to move up and down while rotating.

In the single crystal manufacturing apparatus 1, the single crystal ingot 1 is pulled above the quartz crucible 4 from the silicon melt 9 formed in the quartz crucible 4.
0 is coaxially surrounded, and a heat shield 17 composed of an inverted conical tube whose lower end is close to the interface of the melt 9 and the outer peripheral surface of the single crystal ingot 10 is arranged.
The outer peripheral surface of the upper end of 7 extends through the bottom of the chamber by a hydraulic or gear type elevating mechanism (not shown) located outside the chamber 2, passes through the outside of the heat insulating material 6, and is above the upper end. The heat shield 17 is displaceably supported by the variable support 19 which is extended to

In the single crystal production apparatus of the present invention,
The structure of the variable support that supports the heat shield 17 from below is not particularly limited as long as it supports the heat shield 17 in a displaceable manner. As in the single-crystal manufacturing apparatus 21 of another embodiment shown, the outer peripheral surface of the upper end of the heat shield 17 is connected to the connector 20 extending upward from the upper end of the heat insulator 7, and the cylindrical heat insulator is further connected. The lower end of 7 may be connected to a plurality of variable supports 19 that extend through the bottom of the chamber by an elevating mechanism (not shown) located outside the chamber 2.

Further, in the single crystal pulling apparatus of the present invention, the elevating mechanism for driving the variable support 19 is
A control device (not shown) for displacing the heat shield by the elevating mechanism is connected in connection with the fluctuation of the melt 9 interface accompanying the growth of the single crystal ingot 10.

The material forming the heat shield 17 used in the apparatus for producing a single crystal of the present invention is not particularly limited, and examples thereof include tungsten, niobium, tantalum, steel, nickel, germanium and the like. Various materials such as metal, ceramics such as silicon nitride, silicon carbide and boron nitride, and graphite coated with these ceramics can be used.

The distance between the inner peripheral portion of the lower end of the heat shield 17 and the outer peripheral surface of the single crystal ingot 10 to be grown depends on the size, type, etc. of the single crystal ingot 10 to be manufactured. Cannot be specified, but for example 5
It is about 100 mm.

In order to pull up a single crystal by using the single crystal manufacturing apparatus 1 as described above, first, according to a conventional method, polycrystalline silicon and a dopant added as necessary in the quartz crucible 4 are added. A certain amount of raw material is loaded and the heater 5
Is heated to melt the raw material to form a melt 9. Then, the heat shield 17 is displaced by the variable support 19 and held at a desired position where the distance between the interface of the melt 9 and the lower end of the heat shield 17 is, for example, 5 to 100 mm. After that, the seed crystal 12 attached to the tip of the pulling wire 14 is immersed in the melt 9, and the quartz crucible 4 and the seed crystal 12 are pulled up while rotating, and the single crystal ingot 10 is grown at the lower end of the seed crystal 12. As the growth of the single crystal ingot 10 progresses, the amount of the melt 9 decreases and its interface lowers. Therefore, the elevating mechanism of the variable support 19 is driven, and the displacement amount is controlled by the control device while heat shielding is performed. Body 17
Change the height of the to a predetermined height. If necessary, the quartz crucible 4 can be gradually raised as the single crystal pulling operation proceeds, as in the conventional case.

Thermal shield 17 during pulling operation of a single crystal
The amount of displacement of is based on the weight of the single crystal ingot, the pulling rate, the temperature of the single crystal growth interface, the position of the quartz crucible 4, etc., which are gradually detected so that the heat distribution near the single crystal growth interface can be kept constant. Is controlled by the control device according to a pre-installed program.

Although various modes are conceivable as this control method, for example, the heat shield 17 is lowered as the interface of the melt 9 is lowered, and the distance between the interface of the melt 9 and the lower end of the heat shield 17 is set. By keeping it constant throughout the single crystal pulling operation, the amount of radiant heat to the single crystal growth interface and the gas flow in the vicinity of the growth interface are made almost constant through the single crystal pulling operation, and the single crystal growth optimum condition is maintained constant. Maintains a constant thermal history in the high temperature range, which has a large effect on crystal quality,
A high quality and homogeneous single crystal can be obtained. Alternatively, the quartz crucible 4 is raised in order to keep the height of the melt 9 interface constant with the decrease in the amount of the melt 9, while the heat shield 17 is displaced to move the quartz crucible 4 and the heater. A change in the amount of radiant heat to the single crystal growth interface and a change in the gas flow in the vicinity of the growth interface due to a change in the relative position with respect to No. 5 may be offset by the displacement of the heat shield 17.

[0024]

As described above, according to the present invention, a heat shield composed of an inverted conical tubular body disposed in a single crystal manufacturing apparatus is supported so as to be vertically movable from below, and this heat shield By gradually displacing the arrangement position to a predetermined position during single crystal growth, the single crystal growth conditions can be maintained constant throughout the single crystal growth operation, which results in good and uniform quality over the entire length. A single crystal ingot can be obtained.

[Brief description of drawings]

FIG. 1 is a use state diagram schematically showing a configuration of an embodiment of a single crystal production apparatus of the present invention,

FIG. 2 is a use state diagram schematically showing the configuration of another embodiment of the single crystal production apparatus of the present invention,

FIG. 3 is a use state diagram schematically showing a configuration of a conventional single crystal manufacturing apparatus.

[Explanation of symbols]

1, 21 ... Single crystal manufacturing apparatus, 2 ... Chamber, 2a ... Heating chamber section, 2b ... Pulling chamber section, 3 ... Rotation axis, 4
... quartz crucible, 5 ... heater, 6 ... heat insulating material, 7 ... graphite crucible, 8 ... graphite crucible, 9 ... silicon melt, 10 ... single crystal ingot, 11 ... wire pulling device, 12 ... seed crystal, 13 ... Chuck, 14 ... Pulling wire, 15 ... Inert gas introduction port, 16 ... Gas exhaust port, 17 ... Heat shield, 1
8 ... Support body, 19 ... Variable support body, 20 ... Connection body.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kiyoshi Kojima, 3434 Shimada, Hitsu-shi, Yamaguchi Prefecture, Nittetsu Denshi Co., Ltd. 72) Inventor Shigeyoshi Takao 3434 Shimada, Hikari City, Yamaguchi Prefecture Nippon Steel Corporation Hikari Steel Works Ltd.

Claims (1)

[Claims] 1. A single crystal manufacturing apparatus used for pulling a single crystal ingot while growing it from a melt in a crucible, wherein the growing single crystal ingot is coaxially surrounded, and its lower end is the outer periphery of the single crystal ingot. It has a heat shield consisting of an approximately conical tube that is close to the surface, is connected to the outer peripheral surface of the upper end of this heat shield, and supports this inverted conical tube from below on the side of the crucible. The support is provided with an elevating mechanism, and further has a control means for displacing the heat shield by the elevating mechanism in relation to the change of the melt interface accompanying the growth progress of the single crystal ingot. Single crystal manufacturing equipment.