JPH08119790A - Semiconductor single crystal pull device - Google Patents

Abstract

PURPOSE: To provide a semiconductor single crystal pull device of shaft scheme reduced in height, designed to prevent the life time of single crystals produced from being shortened due to metallic powder falling from the periphery of the force bar onto the melt, by dividing a pull shaft into upper and lower shafts which are mutually connected with a wire, and installing a means to conduct vertical motions of the lower shaft. CONSTITUTION: A pull shaft is divided into upper and lower shafts and they are mutually connected with a wire and when a single crystal is to be drawn out of an oven; in this case, if the rise of the upper shaft is halted and the lower shaft is driven, only the portion below the lower shaft can be raised; therefore, a single crystal of continuous length can be pulled up even there is no need of increasing the whole height of the device. The figure shows the gross structure of the pull shaft based on weight-type diameter control scheme. As shown in the figure, a force bar having been conventionally integral construction, is made up of the upper shaft 1, wire 2, lower shaft 3, and force bar 4 (made of carbon), being revolvable integratedly with a weight sensor 5 and a seed chuck 6, and standing enclosed as a whole by a guide shaft 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor single crystal pulling apparatus.

[0002]

2. Description of the Related Art A high-purity single crystal silicon is mainly used for a substrate of a semiconductor element, and the Czochralski method (hereinafter referred to as CZ method) is often used as a method for producing this single crystal silicon. The semiconductor single crystal pulling apparatus by the CZ method is roughly classified into a shaft system and a wire system structurally, and an optical system and a weight system from a single crystal diameter control system. Figure 6 is a shaft system,
FIG. 1 is a schematic diagram showing a schematic configuration of a weight-type diameter control type semiconductor single crystal pulling apparatus. The pulling shaft for pulling the single crystal silicon 31 is a force bar 32 connecting the weight sensor 5 and the seed chuck 6, the seed chuck 6, and a collar 33 for preventing steadying of the force bar 32.
And a guide shaft 34 that holds the collar 33. Further, the weight sensor 5 and the force bar 32, and the force bar 32 and the seed chuck 6 are connected by screws or pins, respectively.
Generally, molybdenum steel is used as the material and stainless steel is used as the other lifting shaft parts.

A crucible 36 installed in the main chamber 35 is filled with high-purity polycrystalline silicon, and this polycrystalline silicon is heated and melted by a heater 37 surrounding the outer circumference of the crucible 36, and a melt 38 is formed. And Then, the seed crystal attached to the seed chuck 6 is immersed in the melt 38, and the pulling shaft 32, 6, 33, 34 and the crucible 36 are rotated in the same direction or in the opposite direction to raise the pulling shaft, Grow single crystal silicon. In addition, 39 is a cylindrical heat insulating material provided around the heater 37, 40 is a crucible shaft, and 13 is a bellows which constitutes an upper chamber.

[0004]

In recent years, the diameter of single crystal silicon has tended to increase, and the total length of single crystal silicon also increases accordingly. Therefore, the overall height of a shaft type single crystal pulling apparatus is increasing. is there. As the height of the apparatus increases, the cost of the building and the like also rises. Therefore, it is necessary to improve the pulling axis of the single crystal pulling apparatus to suppress the increase in the apparatus height. Moreover, specifications such as lifetime of a semiconductor substrate are becoming more important. However, in the case of the pulling shaft used in the general weight type diameter control type semiconductor single crystal pulling device, the contact between the force bar and the steady rest is particularly strong, and the dropping of metal powder into the melt should be avoided. However, this is one of the causes for reducing the lifetime of the semiconductor substrate.

The present invention has been made by paying attention to the above-mentioned conventional problems. The height of a shaft type semiconductor single crystal pulling apparatus is reduced, and the lifetime of metal powder falling from around the force bar into the melt is reduced. It is an object of the present invention to provide a semiconductor single crystal pulling apparatus capable of preventing the decrease in the semiconductor single crystal.

[0006]

In order to achieve the above object, a semiconductor single crystal pulling apparatus according to the present invention comprises a crucible for melting a raw material of a semiconductor single crystal and a raw material in a crucible surrounding the crucible. In a shaft type semiconductor single crystal manufacturing apparatus provided with a heater for heating and a pulling mechanism for pulling a single crystal by immersing a seed crystal in a melted raw material, a pulling shaft is divided into an upper shaft and a lower shaft, The shaft and the lower shaft are connected by a wire, and a means for moving the lower shaft up and down is provided. Further, in the shaft type and weight type diameter control type semiconductor single crystal manufacturing apparatus, the upper shaft attached to the lower end of the weight sensor and the lower shaft attached to the upper end of the force bar are connected by a wire,
A structure for providing a means for moving the force bar up and down,
In such a configuration, the upper end is fixed to the lower end of the weight sensor, and the inner circumference of the guide shaft surrounding the upper part of the upper shaft, the wire, the lower shaft and the force bar,
A plurality of balls made of stainless steel or ceramics may be slidably disposed between the outer periphery of the force bar and
The upper end is fixed to the lower end of the weight sensor, and a guide collar made of carbon material is provided between the inner circumference of the guide shaft surrounding the upper shaft, the wire, the lower shaft and the upper part of the force bar, and the outer circumference of the force bar. Good. Further, the semiconductor single crystal pulling apparatus according to the present invention is characterized by using a carbon material for the force bar.

[0007]

According to the above construction, in the shaft type semiconductor single crystal pulling apparatus using the CZ method, the pulling axis is divided into upper and lower parts and the wire is connected between them, so that the grown single crystal silicon is taken out of the furnace. When taking out, if the raising of the upper shaft is stopped and the lower shaft elevating means is driven, the wire sags and only the portion below the lower shaft can be raised. Therefore, it is possible to pull the single crystal silicon longer than the conventional one without increasing the total height of the semiconductor single crystal pulling apparatus. Further, with respect to the weight-based diameter control type semiconductor single crystal pulling apparatus, the force bar and the guide shaft are configured to be in contact with each other through a plurality of balls made of stainless steel or ceramics or a guide collar made of carbon material. Therefore, the amount of metal powder falling from around the force bar is reduced, and it is possible to prevent the lifetime of the semiconductor substrate from being reduced. Further, the force bar made of carbon material has much higher heat resistance than that made of stainless steel, so that the service life is extended and the heat in the furnace is less likely to be transmitted to the weight sensor.

[0008]

Embodiments of the semiconductor single crystal pulling apparatus according to the present invention will be described below with reference to the drawings. FIG.
FIG. 1 is a sectional view showing a schematic structure of a lifting shaft according to a first embodiment of a weight type diameter control system. The conventional force bar is composed of an upper shaft 1, a wire 2, a lower shaft 3 and a force bar 4. ing. The upper shaft 1 is made of stainless steel, a weight sensor 5 is screwed on the upper end thereof, and a tungsten steel wire 2 is attached on the lower end thereof. A lower shaft 3 made of stainless steel is attached to the lower end of the wire 2, and an upper end of a force bar 4 made of carbon material is screwed to the lower shaft 3. Also, the lower end of the force bar 4 is made of carbon material,
A seed chuck 6 holding a seed crystal (not shown) is screwed on. The upper shaft 1, the wire 2, the lower shaft 3, and the upper portion of the force bar 4 are hollow stainless steel guide shafts 7 that rotate integrally with the weight sensor 5.
Be surrounded by. The force bar 4,
The seed chuck 6 is designed in consideration of a sufficient safety factor in terms of strength, and is less likely to be thermally deformed as compared with a conventional one made of stainless steel.

FIG. 2 shows a lower shaft 3 and a force bar 4.
FIG. 4 is a cross-sectional view illustrating the structure around the upper part of FIG. A wire fixing screw 8 made of stainless steel is screwed onto the upper end of the lower shaft 3. As shown in FIG. 3, the wire fixing screw 8 is provided with holes 8a and 8b having different diameters at its axial center, and a conical surface is formed at the boundary of these holes. The hole 8a is a hole for passing the wire 2. Further, one slit 8c extending from the outer circumference to the holes 8a and 8b is provided along the axis. A wire fixing screw having the same structure as the wire fixing screw 8 is also screwed to the lower end of the upper shaft 1.

Balls made of stainless steel are fixed to both ends of a wire 2 connecting the upper shaft 1 and the lower shaft 3, and the wire 2 is inserted through the slits 8c of the wire fixing screw 8 into the holes 8a and 8b. After that, when the wire 2 is pulled, the balls at both ends of the wire abut on the conical surface of the hole 8b provided in the wire fixing screw 8, respectively.

A spacer 9 is provided on the outer periphery of the upper portion of the force bar 4.
The spacers 9 are attached to the upper and lower ends of the spacer 9, and stainless steel cages 11 for holding the balls 10 made of stainless steel or ceramics are fitted to the spacers 9. The sphere 10
Are arranged in the retainer 11 at equal intervals and can slide on the inner wall surface of the guide shaft 7. Further, in order to prevent the lower retainer 11 from falling, a collar 12 made of stainless steel is attached to the force bar 4 in close contact with the lower surface of the retainer 11.

FIG. 4 is a cross-sectional explanatory view showing a state in which single crystal silicon having completed growth is being pulled into the upper chamber. A cylinder 14 driven by hydraulic pressure or air pressure is provided outside the bellows 13 forming the upper chamber of the semiconductor single crystal pulling apparatus, and a horizontal plate 15 is provided at the lower end of the piston rod 14a of the cylinder 14.
Is attached. The process until the tail of the single crystal silicon is separated from the melt surface and pulled up to a predetermined height is the same as in the conventional shaft system. When the single crystal silicon is pulled up to a predetermined height, the rise of the guide shaft 7 is stopped, and the bellows 13 forming the upper chamber is compressed upward. Then, after the plate 15 is brought into contact with the exposed lower end of the seed chuck 6, the cylinder 14 is driven to the retracting side. As a result, the lower shaft (not shown), the force bar 4, the seed chuck 6, and the single crystal silicon are pushed up, and the wire 2 is slackened. The single crystal silicon rises to the carry-out position while the heights of the weight sensor 5 and the guide shaft 7 are stopped at the predetermined height.

In the case of this embodiment, the force bar 4 has two upper and lower portions.
The point bar 4 is in point contact with the inner circumference of the guide shaft 7 through the balls 10 arranged in a row.
The frictional resistance is small even when moving up in the guide shaft 7, and the falling of the metal powder into the melt is reduced as compared with the force bar of the conventional structure.

FIG. 5 is a sectional view showing the schematic structure of a second embodiment of the lifting shaft of the weight type diameter control system.
A guide collar 2 instead of the cage and the sphere in the embodiment
1 and 22 are used. The guide collars 21 and 2
Reference numeral 2 is made of a carbon material, and the inner and outer circumferences thereof are mirror-finished or covered with a protective film of SiC, and are attached to the upper and lower ends of a spacer 23 made of stainless steel. The fixing bracket 24 made of stainless steel has a lower guide collar 22.
And is attached to the lower end of the guide shaft 7. In addition, the lower guide collar 2
A collar 25 made of carbon material is attached to the force bar 4 below the member 2. The fixing bracket 24 and the collar 2
The reference numeral 5 also has a function of preventing the carbon material powder from falling into the melt due to friction between the guide collars 21 and 22 and the force bar 4 and the guide shaft 7. However, since the frictional resistance is small, the amount of abrasion powder generated is extremely small. The other structure of each part is the same as that of the first embodiment, and detailed description thereof will be omitted.

In the above embodiments, the weight type diameter control type semiconductor single crystal pulling apparatus has been described, but the present invention can also be applied to a shaft type semiconductor single crystal pulling apparatus which performs optical diameter control. it can. Further, although a cylinder that operates hydraulically or pneumatically is used as a means for moving the force bar up and down, a shaft that moves up and down with a ball screw may be used instead of the cylinder, or a method of winding a wire with an electric motor may be used.

[0016]

As described above, according to the present invention, the force bar used in the conventional weight type diameter control type semiconductor single crystal pulling apparatus is divided into a wire portion and a short force bar portion. Then, after pulling the single crystal silicon having completed the crystal growth to a predetermined height, the force bar portion is pushed up. With this improvement, it is not necessary to extend the rising stroke of the pulling shaft in accordance with the axial length of the single crystal silicon, and the total height of the pulling device can be reduced, which increases the equipment cost of the semiconductor single crystal pulling device. Can be suppressed. Also,
Since the force bar and the guide shaft are in contact with each other through a plurality of balls made of stainless steel or ceramics or a guide collar made of carbon material, the metal powder falling from around the force bar is reduced and the life of the semiconductor substrate is reduced. Time reduction can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a lifting shaft according to a first embodiment of a weight type diameter control system.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of a lower shaft and an upper periphery of a force bar.

FIG. 3 is a cross-sectional view of a wire fixing screw.

FIG. 4 is a cross-sectional explanatory view showing a state in which single crystal silicon that has completed growth is being pulled into the upper chamber.

FIG. 5 is a cross-sectional view showing a schematic configuration of a lower shaft of a lifting shaft according to a second embodiment of a weight type diameter control system and an upper periphery of a force bar.

FIG. 6 is a schematic view showing a schematic configuration of a conventional semiconductor single crystal pulling apparatus by a weight type diameter control system.

[Explanation of symbols]

 1 Upper Shaft 2 Wire 3 Lower Shaft 4,32 Force Bar 5 Weight Sensor 7,34 Guide Shaft 10 Ball 11 Cage 14 Cylinder 21, 22 Guide Collar 31 Single Crystal Silicon 36 Crucible 37 Heater

Claims (5)

[Claims] 1. A crucible for melting a raw material of a semiconductor single crystal, a heater for heating a raw material in a crucible around the crucible, and a pulling mechanism for dipping a seed crystal in the melted raw material to pull up the single crystal. In the shaft type semiconductor single crystal manufacturing apparatus having the above-mentioned, the pulling shaft is divided into an upper shaft and a lower shaft, the upper shaft and the lower shaft are connected by a wire, and means for raising and lowering the lower shaft is provided. A semiconductor single crystal pulling apparatus characterized by: 2. In a shaft type and weight type diameter control type semiconductor single crystal manufacturing apparatus, an upper shaft attached to a lower end of a weight sensor and a lower shaft attached to an upper end of a force bar are connected by a wire. A device for pulling a semiconductor single crystal is provided with means for moving up and down the force bar. 3. A stainless steel or ceramics member having an upper end fixed to a lower end of the weight sensor, and an inner periphery of a guide shaft that surrounds an upper shaft, a wire, a lower shaft and an upper portion of the force bar, and an outer periphery of the force bar. 3. A semiconductor single crystal pulling apparatus according to claim 2, wherein a plurality of spheres made of silicon are slidably arranged. 4. The upper end is fixed to the lower end of the weight sensor, and is made of a carbon material between the inner circumference of the upper shaft, the wire, the lower shaft and the guide shaft surrounding the upper part of the force bar, and the outer circumference of the force bar. The semiconductor single crystal pulling apparatus according to claim 2, wherein a guide collar is provided. 5. The semiconductor single crystal pulling apparatus according to claim 2, wherein a carbon material is used for the force bar.