JPH09227274A - Apparatus for producing semiconductor single crystal by continuous charging method and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a semiconductor single crystal from having the dislocation by liquid level vibration at the time the melt surface falls and a raw material supplying pipe detaches from the melt when the raw material supply ends in production of the semiconductor single crystal by a continuous charging method. SOLUTION: The bottom end face of the raw material supplying pipe 24 to be mounted at the raw material supplying section of the apparatus for producing the semiconductor single crystal is inclined at a prescribed angle θ from the axial center of the raw material supplying pipe 24 and further, the bottom end face is provided with a notch 24a. The notch 24a initiates the detachment of the raw material supplying pipe 24 from the liquid at the time the pipe detaches from the melt by falling of the melt surface, and further, the detachment thereof from the liquid is improved by the inclination of the bottomed face. Then, the fall of the melt lifted by adhesion to the bottom end face of the raw material supplying pipe and the consequent occurrence of the melt surface vibration encountered heretofore do not arise. If the pressure of the raw material supplying section is equaled to the pressure of the crystal growing section after the end of the raw material supply, the melt level in the material supplying pipe falls and, therefore, the detachment of the pipe from the liquid is additionally improved.

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 production apparatus and a production method by a continuous charge method for growing a semiconductor single crystal while melting a raw material polycrystalline rod and supplying it to a crucible.

[0002]

2. Description of the Related Art Generally, high-purity single crystal silicon is used for a substrate of a semiconductor element, and the CZ method is mainly used for its production. In the CZ method, a graphite crucible is placed on the upper end of a crucible shaft installed in a chamber of a semiconductor single crystal manufacturing apparatus via a crucible receiver, and a quartz crucible housed in the graphite crucible is loaded with polycrystalline silicon. The polycrystalline silicon is heated and melted by a heater provided around the graphite crucible to form a melt. Then, the seed crystal attached to the seed chuck is immersed in the melt, and the seed chuck is pulled up while rotating the seed chuck and the graphite crucible in the same direction or in the opposite direction to grow single crystal silicon.

In recent years, the diameter of semiconductor wafers has increased, and large-diameter wafers exceeding 6 inches have been required. Single crystal silicon having a diameter of 6 inches or more is becoming the mainstream. For this reason, the semiconductor single crystal manufacturing apparatus tends to be large in size, and the throughput per batch tends to increase. However, the time required for the single crystal growth step becomes longer as the diameter of the single crystal silicon becomes larger, and the steps before and after that, for example, the time required for melting the polycrystalline silicon and after the grown single crystal silicon is taken out of the furnace. The cooling time required for the crucible, the heater, etc. to reach a temperature at which they can be cleaned is longer than before. These are factors that reduce the productivity of single crystal silicon.

As one of the means for efficiently producing large-diameter single crystal silicon by the CZ method, continuous pulling of the single crystal silicon while continuously supplying the raw material into the crucible according to the amount of the grown single crystal silicon. The charge method is used. FIG. 6 is a partial cross-sectional view showing an example of a semiconductor single crystal manufacturing apparatus by the continuous charge method, in which a plurality of raw material supply parts 20 are installed above the peripheral edge of the quartz crucible 3. The raw material supply unit 20 melts rod-shaped polycrystalline silicon (hereinafter, referred to as raw material polycrystalline rod) 21 hung from above the main chamber 1 and drops it into the melt 6. A protective cylinder 23 surrounding the raw material melting heater 22 and a raw material supply pipe 29 attached to the bottom of the protective cylinder 23 are provided. An annular melt cover 26, which serves as a passage for discharging the inert gas introduced into the raw material supply unit 20 from the main chamber 1, is attached to the lower end of the protective cylinder 23, and an exhaust pipe is attached to the outer edge of the melt cover 26. 27 is connected.

The lower portion of the raw material supply pipe 29 is immersed in the melt 6 to prevent vibrations from propagating to the melt 6 of the crystal growing portion 10 by the falling droplets. In addition, the raw material supply unit 2
Since 0 forms an independent space isolated from the single crystal growing portion 10 by the above structure, the vapor phase of the raw material supply portion 20 and the crystal growing portion 10 are separated.

[0006]

When the semiconductor single crystal 7 is pulled up, the pressure of the raw material supply section 20 is controlled by the single crystal growth section 1.
Evacuate to 1 Torr below the pressure of 0. FIG. 7 is an explanatory diagram showing changes in the melt level inside and outside the raw material supply pipe. The lower part of the raw material supply pipe 29 is immersed in the melt 6, but since the pressure of the raw material supply part is 1 Torr lower than that of the single crystal growth part, as shown in FIG. The liquid level rises outside the raw material supply pipe 29, that is, above the melt level of the single crystal growth portion. By this pressure difference,
It is possible to prevent SiO-based dust and impurities generated in the raw material supply section from flowing into the single crystal growth section, and prevent dislocation of the grown semiconductor single crystal.

When a series of semiconductor single crystal growth approaches the end, the supply of the raw material by the melting of the raw material polycrystalline rod ends, and when the quartz crucible 3 rises to the upper limit, the melt surface gradually lowers and the raw material supply pipe The lower end of 29 is separated from the melt 6.
However, since the melt 6 has a large surface tension, it adheres to the lower surface of the raw material supply pipe 29 and is lifted as shown in FIG. 7B. When the melt surface further descends, the melt 6 adhering to the raw material supply pipe 29 suddenly drops, causing liquid surface vibration as shown in FIG. 7C. This liquid level vibration causes dislocation of the single crystal during pulling.

The present invention has been made by paying attention to the above-mentioned conventional problems, and in the production of a semiconductor single crystal by the continuous charge method, the raw material supply is completed, the melt surface is lowered, and the raw material supply pipe is melted. It is an object of the present invention to provide a semiconductor single crystal production apparatus and a production method that do not cause dislocation of a semiconductor single crystal when the semiconductor single crystal is disengaged.

[0009]

In order to achieve the above object, a semiconductor single crystal manufacturing apparatus according to the present invention comprises a crucible for loading a raw material of a semiconductor single crystal, a main heater for melting the raw material in the crucible, and a crucible. A pulling mechanism for immersing the seed crystal in the melt inside to pull up the semiconductor single crystal, and a raw material supply section for melting the raw material by the raw material melting heater provided above the peripheral portion of the crucible and continuously supplying the raw material into the crucible. In the provided semiconductor single crystal manufacturing apparatus, the lower end surface of the raw material supply pipe attached to the bottom of the protective cylinder surrounding the raw material melting heater is inclined at a predetermined angle θ with respect to the axis of the raw material supply pipe,
A notch is provided on the lower end surface.

Further, the semiconductor single crystal manufacturing method according to the present invention uses the semiconductor single crystal manufacturing apparatus according to the above continuous charging method, the pressure of the raw material supply section is reduced from that of the crystal growth section, and the raw material melted by the raw material melting heater is used. In the production of a semiconductor single crystal in which a semiconductor single crystal is grown while being continuously supplied into a crucible, it is characterized in that the raw material supply section and the crystal growth section are brought to an equal pressure after the supply of the raw material is completed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention occurs when the growth of a semiconductor single crystal by the continuous charge method approaches the end and the melt level drops and the raw material supply pipe separates from the melt. It prevents dislocation from occurring due to vibration of the melt surface. When the lower end surface of the raw material supply pipe is tilted at a predetermined angle θ, the liquid dispersal at the time of separation is better than that of the conventional raw material supply pipe without inclination, but this is not sufficient. According to the above configuration, since the lower end surface of the raw material supply pipe is inclined at a predetermined angle θ and the notch is provided, the notch acts as a trigger for liquid leakage at the time of separation, and the conventional raw material supply pipe As described above, the surface tension prevents the melt from adhering to the lower end surface of the raw material supply pipe and lifting it. Therefore, the problem that the melt drops and the melt surface vibrates is eliminated.

Further, after the raw polycrystalline rod is melted,
If the raw material supply part is made to have the same pressure as the crystal growth part, the melt surface in the raw material supply pipe is lowered, and it becomes easier for the raw material supply pipe to come out of the melt.

Next, an embodiment of the semiconductor single crystal manufacturing apparatus by the continuous charging method according to the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view showing a schematic configuration of the semiconductor single crystal manufacturing apparatus. A graphite crucible 2 and a quartz crucible 3 are installed at the center of a main chamber 1 so as to be vertically movable and rotatable, and a main heater 4 is provided around the graphite crucible 2. A heat insulating cylinder 5 is provided. The raw material polycrystal charged in the quartz crucible 3 is melted by the main heater 4 to form a melt 6, and the semiconductor single crystal 7 is pulled up from the central portion of the quartz crucible 3. The central region of the quartz crucible 3 in which the semiconductor single crystal 7 is grown is called a crystal growing part 10.

Above the vicinity of the periphery of the quartz crucible 3, two sets of raw material supply parts 20 are installed so as to face each other. The raw material supply unit 20 melts a raw material polycrystalline rod 21 hung from a pull chamber 8 connected to the upper end of the main chamber 1 and drops it into the melt 6. The raw material melting heater 22 and the raw material melting heater 22 are connected to each other. Protective cylinder 23 surrounding and protective cylinder 23
, A shield cover 25 attached between the upper part of the pull chamber 8 and the upper end of the raw material melting heater 22, and an annular melt attached to the lower part of the protective cylinder 23. It is composed of a cover 26 and an exhaust pipe 27. Raw material melting heater 22 and protective cylinder 23
The gap between the upper part and the upper part is sealed with a quartz material.

Exhaust port 1 provided at the bottom of the main chamber 1.
The exhaust pipe line 11 connected to a and the exhaust pipe line 12 connected to the exhaust pipe 27 at the outer edge of the melt cover 26 meet at a confluence point 1
An exhaust pipe line 14 provided downstream of the confluence point 13 is connected to a vacuum pump 15. The exhaust line 11,
Valves 16, 17 and 18 are provided on 12 and 14, respectively. The valve 17 is for adjusting the pressure of the raw material supply unit 20.

FIG. 2 shows a raw material supply pipe in the first embodiment of the present invention, FIG. 2 (a) is a sectional view, and FIG. 2 (b) is FIG.
It is a Z view of (a). The raw material supply pipe 24 is made of quartz, and its lower end surface has a predetermined angle θ with respect to the central axis of the raw material supply pipe.
And a notch 24a is provided on the lower end surface.

The raw material polycrystalline rods 21 are melted in the raw material melting heater 22 alternately or one by one at a time,
The raw materials are continuously supplied. The raw material polycrystalline rod 21 suspended inside the shield cover 25 is melted from the lower end by the raw material melting heater 22, becomes droplets, passes through the raw material supply pipe 24, and falls into the quartz crucible 3. The lower portion of the raw material supply pipe 24 is immersed in the melt 6 to prevent vibrations from propagating to the melt outside the raw material supply pipe 24, that is, the melt 6 of the crystal growing portion 10 by the droplets. . Further, the raw material supply unit 20 has the crystal growth unit 10 having the above structure.
Since the independent space isolated from the above is formed, the vapor phase of the crystal growth part 10 and the raw material supply part 20 is separated.

A pipe line different from the pipe line for the inert gas introduced into the crystal growing portion 10 is connected to the upper portion of the shield cover 25, and the inert gas is supplied to the two sets of the raw material supply portions 20. be introduced. The inert gas flows down around the raw material polycrystalline rod 21, enters the melt cover 26 through an opening provided in the lower portion of the protective cylinder 23, and the SiO-based dust generated when the raw material polycrystalline rod 21 is melted and the raw material supply portion. The impurities generated in 20 are discharged from the main chamber 1 through the exhaust pipe 27.

On the other hand, the inert gas introduced into the crystal growing portion 10 flows down around the semiconductor single crystal 7 being grown, flows between the melt cover 26 and the melt 6, and the graphite crucible 2
Through the gap between the main heater 4 and the main heater 4 and the gap between the main heater 4 and the heat insulating cylinder 5, and are discharged together with the impurities generated in the crystal growing part 10 from the exhaust port 1a provided at the bottom of the main chamber 1. Further, a part of the inert gas flows down through the gap between the main chamber 1 and the heat insulating cylinder 5, and is discharged from the exhaust port 1a.

Upon pulling up the semiconductor single crystal, the opening of the valve 16 and the valve 17 is adjusted so that the raw material supply unit 20
Is reduced to 1 Torr with respect to the crystal growth portion 10. A pressure sensor is installed in the raw material supply unit 20 and the crystal growth unit 10, and the opening degree of the valve is adjusted based on the respective detected values. Thereby, the raw material supply unit 20
It is possible to prevent the SiO-based dust, impurities, etc., generated in the above from flowing into the single crystal growth portion, and prevent the semiconductor single crystal to be grown from having dislocation.

FIG. 3 is an explanatory diagram showing changes in the melt level with respect to the raw material supply pipe. FIG. 3A shows the melt level inside and outside the raw material supply pipe 24 when the raw material polycrystalline rod is melted and supplied to the melt in the raw material supply section. As described above, the lower part of the raw material supply pipe 24 is immersed in the melt 6, and the pressure of the raw material supply part is 1 Torr lower than that of the crystal growth part. It rises by Δh from the outer side, that is, the melt surface of the single crystal growth portion.

When the supply of the raw material by the melting of the raw material polycrystalline rod is completed, the opening of the valve 17 shown in FIG. 1 is reduced, and the crystal growing portion and the raw material supplying portion are made to have the same pressure. As a result, FIG.
As shown in (b), the melt levels inside and outside the raw material supply pipe 24 become equal. Further, since the semiconductor single crystal is continuously pulled up even after the supply of the raw materials is completed, the melt level is constant while the quartz crucible and the graphite crucible are being raised in accordance with the melt decrease amount, When the position of reaches the upper limit, the position of the melt surface with respect to the raw material supply pipe 24 begins to fall as shown in FIG.

When the melt surface descends, a part of the lower end of the raw material supply pipe 24 is exposed from the melt 6 as shown in FIG. 3 (d). The lower end surface of the raw material supply pipe 24 is inclined with respect to the melt surface,
Further, since the notch 24a is provided, this notch 2
4a gives a chance to get out of the liquid. When the melt surface further descends, the lower end surface of the raw material supply pipe 24 is completely exposed from the melt 6 as shown in FIG. At this time, since the lower end surface of the raw material supply pipe 24 is inclined, the melt 6 is easily spread out, and the amount of the molten liquid adhering to the lower end surface of the raw material supply pipe 24 and being lifted is very small. Therefore, when the raw material supply pipe 24 is separated from the melt surface, the liquid surface vibration hardly occurs,
Dislocation generation of the single crystal during growth is avoided.

FIG. 4 shows a raw material supply pipe in a second embodiment of the present invention, FIG. 4 (a) is a sectional view, and FIG. 4 (b) is FIG.
It is a Z view of (a). At the lower end of the raw material supply pipe 28, inclined surfaces 28a having a predetermined angle θ are provided on both sides of the central axis. As a result, when the raw material supply pipe 28 is detached from the melt, the liquid is better spread and the liquid surface vibration hardly occurs.

In the above embodiment, the continuous charging method in which the raw material polycrystalline rod is melted and supplied to the melt has been described, but the present invention is not limited to this, and continuous charging in which a granular raw material is continuously supplied to the melt. The present invention can be applied to the method. For example, the actual fair 7-11177 shown in FIG.
In the semiconductor single crystal manufacturing apparatus disclosed in the publication, a granular raw material introduced from a hopper 31 installed outside the main chamber 1 to a preheating device 33 via a feeder 32 is used as the preheating device 33. Isolation pipe 34 connected to the lower end of the
Is supplied to the melt 6. The lower end of the isolation tube 34 has the shape shown in FIG. 2 or 4, and when the supply of the granular raw material is completed, the inside of the isolation tube 34 is made to have the same pressure as the crystal growth portion 10, so that the isolation tube at the time of the melt surface lowering The liquid leak of 34 can be smoothly performed.

[0026]

As described above, according to the present invention, the lower end surface of the raw material supply pipe attached to the raw material supply unit of the semiconductor single crystal manufacturing apparatus by the continuous charge method is set to a predetermined position with respect to the axis of the raw material supply pipe. By inclining at an angle θ and further providing a notch on the lower end surface, the melt surface descends and the raw material supply pipe is better off when the raw material supply pipe is separated from the melt. The melt that has adhered to the lower end surface of and is lifted does not fall and cause melt surface vibration. Further, if the pressure of the raw material supply part is made equal to that of the crystal growth part after the end of the raw material supply, the melt surface in the raw material supply pipe is lowered, so that the liquid leakage can be further improved. This makes it possible to prevent dislocation of the grown semiconductor single crystal,
The productivity of semiconductor single crystals is improved.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a schematic configuration of a semiconductor single crystal manufacturing apparatus by a continuous charge method.

2A and 2B show a raw material supply pipe according to the first embodiment of the present invention, FIG. 2A is a sectional view, and FIG. 2B is a Z view of FIG.

3A and 3B are explanatory views showing changes in the melt level with respect to the raw material supply pipe. FIG. 3A is a raw material supply, FIG. 3B is a raw material supply end, FIG. 3C is a melt level lowering, and FIG. When a part of the raw material supply pipe is separated from the melt, (e) shows a state where the raw material supply pipe is completely separated from the melt.

4A and 4B show a raw material supply pipe in a second embodiment of the present invention, FIG. 4A is a sectional view, and FIG. 4B is a Z view of FIG. 4A.

FIG. 5 is a partial cross-sectional view showing a schematic configuration of a semiconductor single crystal manufacturing apparatus by a continuous charge method in which granular raw materials are continuously supplied.

FIG. 6 is a partial cross-sectional view showing a schematic configuration of a conventional semiconductor single crystal manufacturing apparatus by a continuous charge method.

FIG. 7 is an explanatory view showing a change in melt level with respect to a raw material supply pipe according to a conventional technique, in which (a) is during raw material supply and (b) is
(C) shows a state where the raw material supply pipe is completely separated from the melt when the raw material supply pipe is separated from the melt.

[Explanation of symbols]

2 ... Graphite crucible, 3 ... Quartz crucible, 4 ... Main heater,
6 ... Melt, 7 ... Semiconductor single crystal, 10 ... Crystal growth part, 20
... Raw material supply section, 21 ... Raw material polycrystalline rod, 22 ... Raw material melting heater, 23 ... Protective cylinder, 24, 28, 29 ... Raw material supply pipe,
24a ... notch.

Claims (2)

[Claims] 1. A crucible for loading a raw material of a semiconductor single crystal, a main heater for melting the raw material in the crucible, a pulling mechanism for immersing a seed crystal in a melt in the crucible to pull up the semiconductor single crystal, and a crucible In a semiconductor single crystal manufacturing apparatus equipped with a raw material supply section that melts the raw material by a raw material melting heater provided above the peripheral edge and continuously supplies it into the crucible, the raw material supply that is attached to the bottom of the protective cylinder surrounding the raw material melting heater An apparatus for producing a semiconductor single crystal by a continuous charge method, characterized in that a lower end surface of a tube is inclined at a predetermined angle θ with respect to an axis of a raw material supply tube, and a notch is provided on the lower end surface. 2. The semiconductor single crystal manufacturing apparatus according to claim 1, wherein the raw material supply part is depressurized more than the crystal growth part, and the raw material melted by the raw material melting heater is continuously supplied into the crucible while the semiconductor single crystal is produced. In the production of a semiconductor single crystal for growing a crystal, a method for producing a semiconductor single crystal by a continuous charge method, characterized in that the raw material supply part and the crystal growth part are made to have an equal pressure after the supply of the raw material is completed.