WO2003095717A1

WO2003095717A1 - Production method and production device for single crystal

Info

Publication number: WO2003095717A1
Application number: PCT/JP2003/005730
Authority: WO
Inventors: Shoei Kurosaka; Hiroshi Inagaki; Shigeki Kawashima; Nobuyuki Fukuda; Masahiro Shibata
Original assignee: Komatsu Denshi Kinzoku Kabushiki Kaisha
Priority date: 2002-05-10
Filing date: 2003-05-08
Publication date: 2003-11-20
Also published as: TW200307065A; JP2003327491A; TWI231319B; JP4187998B2

Abstract

A production method and a production device for a semiconductor single crystal. The production device (1) for a single crystal comprises a crucible (2) for storing the material melt (4) of a single crystal (7) to be grown, a heater (3) for heating this melt (4), a wire (5) for bringing a seed crystal (6) into contact with the surface of the melt (4) in the crucible (2) to pull up the single crystal (7), a chamber (9) for housing the above members, and a magnet (15) for applying magnetic field. Necking is carried out in the absence of magnetic field, before pulling is stopped, and the heater (3) is temperature-controlled. Then, magnetic field is gradually applied by the magnet (15) until a magnetic field intensity reaches a desired value, and thereafter pulling is resumed. A large-diameter, heavy-weight semiconductor single crystal can be safely pulled up with dislocation at a restriction part removed and without causing breakage at the restriction part.

Description

Description Single crystal manufacturing method and manufacturing apparatus

The present invention relates to a method for manufacturing a semiconductor single crystal by applying a magnetic field and a manufacturing apparatus for realizing the method, and in particular, to keep the diameter of the constricted portion large enough to withstand pulling of a heavy semiconductor single crystal. The present invention also relates to a method and an apparatus for manufacturing a semiconductor single crystal capable of achieving dislocation-free. Background art

There are various methods for producing single crystals, and among them, the Chiyoklarski method (CZ method) is widely used as a method that can be industrially mass-produced for pulling silicon single crystals.

FIG. 6 is a longitudinal sectional view of a single crystal manufacturing apparatus for manufacturing a silicon single crystal by the CZ method. Usually, the crucible 2 used for producing a silicon single crystal has a double structure, and is composed of an inner quartz crucible 2a and an outer black crucible 2b. A heater 3 made of graphite is provided around the crucible 2, and a molten silicon solution 4 melted by the heater 3 is stored in the crucible 2. A pulling wire 5 is used as a means for pulling a silicon single crystal, and a seed crystal 6 is attached to the tip thereof. Then, by bringing the lower end of the seed crystal 6 into contact with the surface of the silicon melt 4 and pulling it up, a single crystal 7 is grown at the lower end.

The surface of the inner quartz crucible 2a is melted by contact with the silicon melt 4 to release oxygen into the silicon melt 4. Since the single crystal 7 produced by the CZ method is pulled up from the silicon melt 4 in the quartz crucible 2a and grown, the grown single crystal 7 elutes from the quartz (Sio2) of the crucible. Contains oxygen. For this reason, even if it is repeatedly subjected to heat treatment in the manufacturing process of ICs and LSIs, it is characterized in that it is unlikely to cause slip and warp. Furthermore, the oxygen precipitates inside form a high-density defect layer by heat treatment near 100 ° C, and impurities present in the surface region of the wafer It also has the effect of reducing objects (so-called intrinsic gettering). As described above, since the amount of oxygen dissolved in the single crystal 7 has various effects on the quality of the wafer, it is necessary to control the amount of oxygen taken into the single crystal 7 in the CZ method.

As a method of controlling the amount of oxygen taken into a single crystal, there is a method in which a magnetic field is applied in combination with the CZ method. This method is called the MCZ method (Magnetic-fiel d_a PP 1 ied CZ method), in which a magnetic field is applied to the silicon melt by a magnet provided around the semiconductor single crystal manufacturing equipment, and the kinematic viscosity of the silicon melt is This is a method in which a silicon single crystal is pulled by the CZ method with the temperature raised. Since the convection of the silicon melt is suppressed by the action of the magnetic field, vibration and temperature fluctuation at the solid-liquid interface due to the convection are reduced, and a stable growth of a silicon single crystal can be promoted. Further, since the reaction between the silicon melt and the quartz crucible (S i 02) is suppressed or promoted, it is an effective method for controlling the oxygen concentration in the silicon single crystal. Because of these characteristics, the MCZ method is widely used as an industrial mass production method for single crystals for semiconductors. Generally, in seeding in which the seed crystal is first brought into contact with the silicon melt by the CZ method or the MCZ method, when the seed crystal is brought into contact with the silicon melt, the slip dislocation generated at high density in the seed crystal by thermal shock is applied. In order to eliminate the dislocations that propagate, so-called seed drawing (necking) is performed, in which the diameter is once reduced to about 2 to 5 mm to form a drawing part. Next, the dislocation-free silicon single crystal is pulled up by a shoulder expanding process by increasing the thickness of the crystal until a desired diameter is obtained. As described above, the necking method is widely known as the Dash NecKing method, and is an important step in pulling a silicon single crystal by the CZ method or the MCZ method.

However, in the production of silicon single crystals by the MCZ method, the convection of the silicon melt is suppressed by the application of a magnetic field, and the temperature fluctuation near the melt surface is reduced, so that the solid-liquid interface becomes stable. As a result, there was a problem that dislocations existing in the seed crystal did not escape in the left-right direction, remained in the narrowed portion, and it was difficult to eliminate dislocations. Therefore, in order to achieve dislocation-free in the MCZ method, it is necessary to make the diameter of the constricted portion even smaller than in the case of pulling a silicon single crystal using the ordinary CZ method, and to constrict the hole until dislocations escape. Was. In the production of silicon single crystals, the weight of the silicon single crystal to be pulled is limited by the diameter of the constricted portion. If the weight exceeds the limit, there is a risk that the constricted portion breaks and the silicon single crystal falls. In particular, in recent years, the weight of silicon single crystals has increased due to the increase in diameter, and it has become more difficult to pull heavy silicon single crystals by the MCZ method. For example, when growing a heavy silicon single crystal to produce a large diameter wafer having a diameter of 30 O mm or more, there is a safety problem such as a thin narrow portion inducing a drop of the silicon single crystal.

In order to solve the above problems, in the MCZ method described in Japanese Patent Application Laid-Open No. H10-74887, the necking step is performed at a low magnetic field strength, so that the neck portion can be relatively thinned without being extremely thin. Achieve dislocation-free operation in a large diameter state. Then, by performing the shoulder expanding process while gradually increasing the magnetic field strength, safe pulling of heavy silicon single crystals is secured.

However, if a magnetic field is randomly applied during the shoulder-spreading process, the convection of the silicon melt is rapidly restrained by the magnetic field. While the convection structure of the silicon melt changes due to this magnetic field constraint, the state of the silicon melt becomes extremely unstable, and the temperature of the silicon melt may fluctuate greatly.

Normally, in the absence of a magnetic field, convection occurs in the silicon melt in the crucible due to heating from the heater. Therefore, the heat given by the heater heats the silicon melt near the inner wall of the crucible, and the heated silicon melt circulates in the crucible by convection, raising the temperature of the entire silicon melt.

On the other hand, the convection of the silicon melt in the crucible is suppressed when the magnetic field is applied. Therefore, the heat given by the heater heats the silicon melt near the inner wall of the crucible, and then slowly relaxes toward the center of the silicon melt by heat conduction instead of convection of the silicon melt. Heat is transferred. Since the amount of heat transferred by heat conduction is smaller than the amount of heat transferred by convection, the temperature of the melt near the inner wall of the crucible rises in order to keep the temperature of the melt near the melting point in the center of the crucible. As described above, when a magnetic field is applied casually in the shoulder-spreading process, a sudden change occurs in the convection structure of the silicon melt when changing from the no-magnetic field state to a desired magnetic field strength, and the temperature of the silicon melt at the solid-liquid interface Can go down and up quickly Was confirmed by experiment. Such a rapid change in the temperature of the silicon melt makes it difficult to control the shape of the pulled silicon single crystal, and further causes the silicon single crystal to have dislocations.

For example, if the seed crystal is brought into contact with the silicon melt in the absence of a magnetic field, pulling is stopped after netting, and the magnetic field strength is gradually increased in that state, the temperature of the silicon melt will fluctuate up and down . As a result, rapid crystal growth occurred from the narrowed portion, and the single crystal became thicker, and the grown crystal rapidly re-dissolved and the single crystal became thinner. This indicates that it is difficult to control the shape of the single crystal when gradually increasing the magnetic field strength while pulling the single crystal.

In addition, the magnetic field strength was gradually increased, and the temperature fluctuation of the silicon melt was allowed to proceed, and the X-ray analysis of a single crystal whose diameter was repeatedly expanded and contracted was performed. Dislocations were introduced in the part. From this, it was found that if a single crystal is manufactured with the temperature fluctuation of the silicon melt accompanying the fluctuation of the magnetic field, the single crystal may be dislocated. Controlling the single crystal shape during such an increase in the magnetic field strength is more difficult with a larger volume of melt. Disclosure of the invention

The invention according to the present application has been made in order to solve the above-described problems, and an object of the invention is to provide a large-diameter, heavy-weight semiconductor single crystal without breaking the drawn portion. An object of the present invention is to provide a method and an apparatus for manufacturing a semiconductor single crystal that can be safely pulled up.

Another object of the invention according to the present application is to provide a method and an apparatus for manufacturing a semiconductor single crystal capable of removing dislocations in a narrowed portion during a necking step.

In order to achieve the above object, a first invention according to the present application is directed to a method in which a tip of a seed crystal is brought into contact with a silicon melt in a no magnetic field, the seed crystal is pulled up, a drawing step is performed, and the seed crystal is pulled up. Stopping the application of a magnetic field, increasing the magnetic field intensity to a desired intensity, and then restarting the pulling of the seed crystal in a state where a magnetic field is applied. is there. Further, the second invention according to the present application provides the above-mentioned silicon molten liquid before applying the magnetic field, while increasing the magnetic field strength, or after increasing the magnetic field strength to a desired strength. The method for producing a single crystal according to the first aspect, wherein the temperature is controlled as follows.

Further, a third invention according to the present application is characterized in that before applying the magnetic field, the temperature of the silicon melt is controlled in a state where the pulling of the seed crystal is stopped. 1 is a method for producing a single crystal according to the invention of 1).

Further, the fourth invention according to the present application is characterized in that, in a absence of a magnetic field, the tip of the seed crystal is brought into contact with a silicon melt, the seed crystal is pulled up, a drawing process is performed, and the pulling of the seed crystal is stopped. A method for producing a single crystal, comprising applying a magnetic field after controlling the temperature of a silicon melt.

Further, in the fifth and sixth inventions according to the present application, the temperature control of the silicon melt is performed, and the magnetic field is applied after a lapse of time sufficient for the temperature of the silicon melt to stabilize. A method for producing a single crystal according to the third or fourth invention, characterized in that:

Further, the seventh and eighth inventions according to the present application are characterized in that the temperature control of the silicon melt is performed in accordance with a change in the diameter of the narrowed portion where the lifting is stopped. A method for producing a single crystal according to the second or fourth invention.

Further, a ninth invention according to the present application is characterized in that, after the resumption of the pulling, the temperature of the silicon melt is controlled before the shoulder expanding step, wherein the single crystal according to the first invention is characterized in that: It is a manufacturing method.

Further, in the tenth invention according to the present application, the temperature of the silicon melt is set so as to cancel a temperature change of the silicon melt due to an increase in the magnetic field strength in the shoulder expanding step after the lifting is restarted. The method for producing a single crystal according to the first aspect of the present invention, wherein control is performed.

Furthermore, the eleventh invention according to the present application provides a crucible containing a single crystal raw material melt to be grown, a heater for heating the melt, and a seed crystal contacting the surface of the melt in the crucible. A single crystal manufacturing apparatus comprising: a pulling means for growing a single crystal by growing the magnetic field; a magnetic field applying means for applying a magnetic field; and a chamber accommodating the above members. In the field, the tip of the seed crystal is brought into contact with the melt, the seed crystal is pulled up, a drawing step is performed, the pulling up of the seed crystal is stopped, the application of a magnetic field is started, and the magnetic field strength is increased to a desired strength. The apparatus for producing a single crystal according to claim 1, further comprising control means for controlling the pulling means and the magnetic field applying means so as to restart the pulling of the seed crystal in a state in which the single crystal is pulled.

Further, a twelfth invention according to the present application provides a crucible containing a single crystal raw material melt to be grown, a heater for heating the melt, and a seed crystal contacting the surface of the melt in the crucible. A single crystal manufacturing apparatus comprising: a pulling unit that grows a single crystal by applying a magnetic field; a magnetic field applying unit that applies a magnetic field; and a chamber that accommodates each of the members. After the time required for stabilization has elapsed, the heater and the control means for controlling the magnetic field applying means so as to excite the magnetic field applying means to a desired magnetic field intensity. Use the device.

Brief description of the drawings, '

FIG. 1 is a longitudinal sectional view showing a state where a single crystal manufacturing apparatus of the present invention pulls a single crystal.

FIG. 2 is a longitudinal sectional view showing a state where the single crystal manufacturing apparatus of the present invention has stopped pulling a seed crystal.

FIG. 3 is a longitudinal sectional view showing a state where the single crystal manufacturing apparatus of the present invention is performing a shoulder expanding step. ,

FIG. 4 is a timing chart showing a relationship between ΔN, OFF of the pulling up and the application of the magnetic field in the first embodiment. '

Fig. 5 (a) is a timing chart showing ON / OFF of the lifting, Fig. 5 (b) is the heater temperature, Fig. 5 (c) is the temperature of the silicon melt, and Fig. 5 (d) is a timing chart showing the magnetic field strength. is there.

FIG. 6 is a longitudinal sectional view of a single crystal manufacturing apparatus for manufacturing a silicon single crystal by the CZ method.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of a single crystal manufacturing method and a manufacturing apparatus according to the present application, FIG. This will be described in detail based on the plane.

FIG. 1 is a longitudinal sectional view showing a single crystal manufacturing apparatus.

Reference numeral 2 in the figure denotes a crucible, which has a double structure of a quartz crucible 2a on the inside and a graphite crucible 2b on the outside, and is set on a crucible support shaft 2c. The chamber 9 constituting the appearance of the single crystal manufacturing apparatus 1 is made of stainless steel with little contamination to silicon, and is a cylindrical container arranged around a single crystal pulling shaft. A crucible 2 is disposed at the center thereof, and a heater 3 for heating the silicon melt 4 in the crucible 2 is provided around the crucible 2 around the crucible 2. The heater 3 is made of isotropic graphite, and the temperature of the heater 3 is controlled by adjusting the set power by the temperature controller 14 arranged outside the chamber 9.

Outside the heater 3, a cylindrical heat insulating cylinder 11 is arranged so as to surround the outer periphery of the heater 3. The heat retaining cylinder 11 serves to prevent the chamber 9 from being damaged by heat from the heater 3 and to maintain the temperature in the heat retaining cylinder 11 at a high temperature. As a material of the heat retaining cylinder 11, a carbon fiber material is mainly used.

On both left and right sides of the chamber 9, a pair of magnets 15 as magnetic field applying means are arranged to face each other in a vertically standing state. As the magnet 15, use is made of an electromagnet, a superconducting magnet, or the like having a variable magnetic field strength. As another method of applying a variable magnetic field, a permanent magnet having a variable distance from the silicon melt 4 can be used instead. Further, a cusp magnetic field may be applied by the upper magnet and the lower magnet. The output of the magnet 15 is controlled by the magnetic field controller 16.

On the other hand, above the crucible 2, a wire 5 is suspended from the center of the upper part of the chamber 9 as a single crystal pulling means so as to be rotatable and vertically movable, and a seed chuck 8 is provided at the lower end thereof. The seed crystal 6 is held by the seed chuck 8 and raised while the seed crystal ⁶ is rotated by the wire 5, whereby a single crystal 7 grows on the solid-liquid interface that is the contact surface with the silicon melt ^4. .

The single crystal manufacturing apparatus 1 also includes a television camera 19 and a camera controller unit 20 for observing a change in the diameter of the single crystal 7 at the solid-liquid interface. In addition, the display 21 is connected to the camera control unit 20, and images taken by the TV camera 19 are displayed on the display 21 for visualization. ing. The operator can observe the change in the diameter of the single crystal 7 from the display 21 and adjust the set temperature of the temperature controller 14 in accordance with the change in the diameter of the single crystal 7 to change the heater 3. Control the temperature. In addition, instead of the TV camera 19 or in combination with the TV camera 19, the temperature change of the solid-liquid interface is measured by a temperature measuring means such as an infrared thermometer, and the temperature controller 14 is controlled based on the temperature change. The temperature of the heater 3 may be controlled by adjusting the set temperature. These operations may be performed manually by an operator, or may be a mechanism capable of automatically connecting the camera controller unit 20 or the temperature measuring means and the temperature controller 14 to each other and automatically providing feedback.

Although not shown in FIG. 1, a radiation screen is provided above the crucible 2 so as to surround the periphery of the single crystal 7 to be pulled, so as to increase the pulling speed of the single crystal 7 and promote efficient growth. May be provided. On the bottom surface of the chamber 9, there is provided a receiving tray 18 for receiving the silicon melt 4 from the crucible 2 in case of accident.

A supply port 12 is provided at an upper portion of the chamber 9, and a high-purity argon gas is constantly supplied from the supply port 12 to adjust the atmosphere of the chamber 9 and discharge evaporated substances. The argon gas may be supplied by a commonly used method, and liquid argon is used as a raw material, and is supplied into the chamber 9 after gasification. A discharge port 10 is provided at the lower part of the chamber 9 and a vacuum pump 13 is connected thereto. The argon gas is supplied from the supply port 12, flows downward over the crucible 2, and is discharged from the discharge port 10 by the vacuum pump 13 (see the arrow in FIG. 6).

[Example 1]

A method for manufacturing a semiconductor single crystal using the semiconductor single crystal manufacturing apparatus 1 shown in FIGS. 1 to 3 will be described.

First, high-purity polycrystalline silicon is roughly crushed and washed, then put into crucible 2 and heated by heater 3. At this time, a small amount of a conductive impurity (additive or doping agent) is simultaneously added in a required amount. Boron (B) is added to obtain a P-type crystal, and phosphorus (P) or antimony (Sb) is added to form an N-type crystal. The resistivity of the crystal is controlled by the amount of impurities added. In this case, the magnetic field controller 16 controls the magnet 15 Is controlled to a non-excited state, and no magnetic field is applied to the silicon melt 4.

The seed crystal 6 is held by the seed chuck 8 provided at the lower end of the pulling wire 5, and the seed crystal 6 is brought into contact with the silicon melt 4. Then, as shown in FIG. 2, the wire 5 is wound up while the crucible 2 and the seed crystal 6 are rotated, and the seed crystal 6 is pulled upward. In seeding in which the seed crystal 6 is brought into contact with the silicon melt 4, a seed crystal having a diameter of 12.7 mm is reduced to about 5 mm in order to eliminate dislocations propagating from slip dislocations generated at high density in the seed crystal 6. A necking is performed to form a narrowed portion 17 by narrowing.

In the conventional MCZ method, a magnetic field is applied to the silicon melt 4 at the time of seeding, the convection of the silicon melt 4 is suppressed, and the solid-liquid interface is in a stable state. Dislocations existing in 6 do not escape in the left-right direction and remain inside the constricted portion, making it difficult to eliminate dislocations. Therefore, in the conventional M CZ method, the diameter of the constricted portion had to be reduced to 2 mm. On the other hand, in the single crystal manufacturing method of the present invention, necking is performed in the absence of a magnetic field, so that the diameter of the narrowed portion 17 may be about 5 mm.

Figure 4 shows a timing chart showing the relationship between pulling up and applying a magnetic field. The horizontal axis is the time axis [min], and the vertical axis is the upward ON, OFF, and magnetic field strength [T] (tesla). After necking as described above, the winding of the pulling wire 5 is stopped, and the pulling of the seed crystal 6 is stopped. In FIG. 4, the time at which the lifting stops is set to 0 [min] on the time axis.

Next, with the pulling of the seed crystal 6 stopped, after about 15 minutes have passed, the magnet 15 is excited by the magnetic field controller 16 and the application of a magnetic field to the silicon melt 4 is started. The magnetic field strength of the magnet 15 is gradually increased with time. This embodiment

At 1, the value is raised to 0.3 to 0.4 Tesla [T] over about one hour. The rate of increase of the magnetic field strength of the magnet 15 may be constant over time, or may be changed over time. Rate of increase in the magnetic field strength can be programmed controlled by the magnetic field controller 1 6 shown in ^FIG. For example, changing the output of the magnet 15 by adjusting the magnetic field controller 16 based on the image captured by the TV camera 19 so that the diameter of the aperture 17 at the solid-liquid interface becomes constant. Can also You.

After increasing the magnetic field strength of the magnet 15 to a desired value, the magnetic field controller 16 sets the magnetic field strength to a constant value. Then, the magnetic field intensity is set to a constant value, and after 5 minutes or more, the winding of the pulling wire 5 is restarted. More preferably, after the elapse of 15 minutes or more, the winding of the lifting wire 5 is restarted.

At this time, it is determined whether or not the temperature state of the silicon melt 4 is appropriate based on how the diameter of the narrowed portion 17 is increased or decreased with respect to the lifting speed, and if necessary, a temperature correction operation of the heater 3 is performed. After that, the growth phase may be shifted to the shoulder expanding step. Next, as shown in FIG. 3, a shoulder expanding step is performed in a state where a magnetic field is applied, and the single crystal 7 is thickened until a desired diameter is obtained. Then, a straight body is formed as shown in FIG. For example, when manufacturing a semiconductor wafer having a diameter of 30 O mm, the diameter of the single crystal 7 is enlarged until the diameter becomes slightly larger than 30 O mm, and then the straight body is formed. At this time, the magnetic field may be maintained at a constant value, or may be changed according to a change in the diameter of the single crystal 7.

As described in the related art, the temperature of the silicon melt 4 during the increase of the magnetic field strength is not stabilized, and fluctuates rapidly. Therefore, it is not preferable to perform the shoulder expanding step in that state. Experiments have shown that when 5 minutes or more have passed since the magnetic field strength was kept constant, the temperature of the silicon melt 4 was stabilized and the state of the solid-liquid interface was also stabilized.

According to the first embodiment, with the pulling of the seed crystal 6 stopped in this way, the magnetic field strength is gradually increased from the non-magnetic field, and when the magnetic field strength increases to a predetermined value, a constant value is maintained. Then, after a sufficient time has passed for the temperature change of the silicon melt 4 to stabilize, the pulling of the seed crystal 6 is restarted, and the process proceeds to the shoulder expanding step. As a result, the variation of the convection structure of the silicon melt 4 is suppressed, and the shoulder spreading process can be performed after the melt temperature is stabilized, so that the shape of the pulled silicon single crystal ⁷ can be easily controlled. Further, since necking is performed in the absence of a magnetic field, dislocation-free silicon single crystal 7 can be effectively achieved even when the diameter of aperture portion 17 is relatively large.

[Example 2]

Next, another method for manufacturing a semiconductor single crystal will be described. In Example 1, it was found that a magnetic field was applied to the silicon melt 4 and the temperature of the silicon melt 4 during the increase in the magnetic field strength was on average decreased while fluctuating up and down. Therefore, in the second embodiment, the temperature of the heater 3 is also controlled.

First, similarly to the first embodiment, the seed crystal 6 is held by the seed chuck 8 provided at the lower end of the pulling wire 5, and the seed crystal 6 is brought into contact with the silicon melt 4. Then, as shown in FIG. 2, the wire 5 is wound up while the crucible 2 and the seed crystal 6 are rotated, and the seed crystal 6 is pulled up. In the seeding in which the seed crystal 6 is brought into contact with the silicon melt 4, a seed crystal having a diameter of 12.7 mm is removed from the seed crystal 6 in order to eliminate dislocations propagating from slip dislocations generated at high density in the seed crystal 6. The necking for forming the squeezed portion 17 by once thinning to about mm is performed.

After necking, stop winding the pulling wire 5 and stop pulling the seed crystal 6.

Figure 5 shows a timing chart showing the relationship between the heater temperature, the silicon melt temperature, and the application of a magnetic field. The horizontal axis is the time axis, and the vertical axis is ( _a ) Pull ON, OFF,

(b) Heater temperature [° C], (c) Silicon melt temperature [. C] and (d) Magnetic field strength [T] (Tesla). In FIG. ⁵ , the point of time when the lifting is stopped is set to 0 [min] on the time axis.

The pulling of the seed crystal 6 is stopped (FIG. 5 (a)), and after about 1 to 5 minutes have elapsed, the set temperature of the heater 3 is increased by the temperature controller 14 (FIG. 5 (b)). In the second embodiment, the temperature is set to about 10 to 20 ° C. higher than the normal heater temperature. As the temperature of the heater 3 rises, the temperature of the silicon melt 4 also rises (Fig. 5 (c)).

It takes about 5 to 15 minutes for the temperature of the silicon melt 4 to stabilize. Then, after a lapse of sufficient time for the temperature of the silicon melt 4 to stabilize, the magnetic field controller 16 starts excitation of the magnet 15 and applies a magnetic field to the silicon melt ⁴ (FIG. 5 (d) ). The magnetic field strength of the magnet 15 is gradually increased over time. In this embodiment, the pressure is increased to 0.3 to 0.4 Tesla [T] over about one hour. The rate of increase of the magnetic field strength of magnet 15 is constant over time Or may change over time. The rate of increase of the magnetic field strength is

The program can be controlled by the magnetic field controller 16 shown in FIG. For example, the output of the magnet 15 can be changed by adjusting the magnetic field controller 16 based on the image captured by the TV camera 19 so that the diameter of the aperture 17 at the solid-liquid interface is constant. .

FIG. 5 shows an example in which the temperature of the heater 3 is kept constant while the magnetic field strength is gradually increased, but the temperature of the heater 3 may be varied. For example, in the initial stage of the application of the magnetic field, the convective structure of the silicon melt 4 undergoes a sudden change, so that the temperature of the silicon melt 4 fluctuates greatly. For this reason, as shown in Fig. 2, the expansion and contraction of the diameter of the diaphragm section 17 whose lifting is stopped during application of the magnetic field is photographed with a television camera 19, and the temperature controller 14 is adjusted while observing the display 21. The temperature of the silicon melt 4 can be stabilized by positively performing fine adjustment of the temperature of the heater 3. Also, the temperature controller 14 may be program-controlled to offset the temperature fluctuation of the silicon melt 4 caused by the magnetic field fluctuation.When the magnetic field strength of the magnet 15 is increased to a desired value, the magnetic field controller 16 The magnetic field strength to a constant value. Then, after the magnetic field intensity is set to a constant value and 5 minutes or more have elapsed, winding of the pulling wire 5 is resumed. More preferably, after the elapse of 15 minutes or more, the winding of the lifting wire 5 is restarted.

At this time, it is determined whether or not the temperature state of the silicon melt 4 is appropriate based on how the diameter of the narrowed portion 17 is increased or decreased with respect to the lifting speed, and if necessary, a temperature correction operation of the heater 3 is performed. After that, the growth phase may be shifted to the shoulder expanding step. Next, as shown in FIG. 3, a shoulder expanding step is performed in a state where a magnetic field is applied, and the single crystal 7 is thickened until a desired diameter is obtained. Then, a straight body is formed as shown in FIG. For example, when manufacturing a semiconductor wafer having a diameter of 30 O mm, the diameter of the single crystal 7 is enlarged until the diameter becomes slightly larger than 30 O mm, and then the straight body is formed. At this time, the magnetic field strength may be maintained at a constant value, or may be changed according to a change in the diameter of the single crystal 7.

According to the second embodiment, when the magnetic field is applied by increasing the temperature of the heater 3 Since the temperature drop of the silicon melt 4 can be canceled, fluctuations in the diameter of the narrowed portion 17 can be suppressed.

Of course, if the temperature of the silicon melt 4 rises on average while the magnetic field applied to the silicon melt 4 is gradually increasing, the temperature of the heater 3 may be controlled to decrease.

In the semiconductor single crystal manufacturing apparatus 1 shown in FIGS. 1 to 3 for realizing the first embodiment or the second embodiment, the pulling of the seed crystal 6 and the stopping of the pulling, the control of the temperature controller 14 and the control of the magnetic field controller 16 are well known. Automatic control is also possible by linking them with each other by control means.

ADVANTAGE OF THE INVENTION According to the single crystal manufacturing method and manufacturing apparatus of this invention, a large-diameter and heavy semiconductor single crystal can be safely pulled up without causing breakage of a drawing part.

Further, according to the method and the apparatus for producing a single crystal of the present invention, dislocations in the narrowed portion can be effectively removed during the necking step.

Claims

The scope of the claims

1. In the absence of a magnetic field, the tip of the seed crystal is brought into contact with the silicon melt, the seed crystal is pulled up, and a drawing process is performed.

Stop pulling up the seed crystal, start applying a magnetic field,

After increasing the magnetic field strength to a desired strength, the pulling of the seed crystal is resumed with the magnetic field applied,

A method for producing a single crystal, comprising:

2. Before applying the magnetic field, or while increasing the magnetic field strength, or after increasing the magnetic field strength to a desired strength,

Performing temperature control of the silicon melt;

2. The method for producing a single crystal according to claim 1, wherein:

3. Before applying the magnetic field, perform temperature control of the silicon melt in a state where the pulling of the seed crystal is stopped.

2. The method for producing a single crystal according to claim 1, wherein:

4. In the absence of a magnetic field, the tip of the seed crystal is brought into contact with the silicon melt, the seed crystal is pulled up, and the drawing process is performed.

Stop pulling the seed crystal,

Applying a magnetic field after controlling the temperature of the silicon melt;

A method for producing a single crystal, comprising:

5. performing the temperature control of the silicon melt and applying the magnetic field after a lapse of time sufficient for the temperature of the silicon melt to stabilize;

4. The method for producing a single crystal according to claim 3, wherein:

6. performing the temperature control of the silicon melt, applying the magnetic field after a lapse of time sufficient for the temperature of the silicon melt to stabilize,

5. The method for producing a single crystal according to claim 4, wherein:

7. Perform the temperature control of the silicon melt in accordance with a change in the diameter of the narrowed portion where the lifting is stopped.

3. The method for producing a single crystal according to claim 2, wherein:

8. In accordance with the change of the diameter of the drawing part where the lifting is stopped, the silicon melting Performing the temperature control of the liquid,

5. The method for producing a single crystal according to claim 4, wherein:

9. After the above resumption,

Performing a temperature control of the silicon melt before the shoulder expanding step,

2. The method for producing a single crystal according to claim 1, wherein:

1 0. After resuming the withdrawal,

In the shoulder expanding step, the temperature of the silicon melt is controlled so as to cancel the temperature change of the silicon melt due to the increase in the magnetic field strength.

2. The method for producing a single crystal according to claim 1, wherein:

11. A crucible containing a single crystal raw material melt to be grown, a heater for heating the melt, and a pulling means for growing a single crystal by bringing a seed crystal into contact with the surface of the melt in the crucible; In a single crystal manufacturing apparatus comprising: a magnetic field applying means for applying a magnetic field; and a chamber for accommodating each of the members.

In the absence of a magnetic field, the seed crystal tip is brought into contact with the melt, the seed crystal is pulled up, a squeezing process is performed, the pulling up of the seed crystal is stopped, the application of a magnetic field is started, and the magnetic field strength is increased to a desired strength. And a control means for controlling the pulling means and the magnetic field applying means so as to restart the raising of the seed crystal bow I in a tilted state.

1 2. A crucible containing a single crystal material melt to be grown, a heater for heating the melt, and a pulling means for growing a single crystal by bringing a seed crystal into contact with the surface of the melt in the crucible; In a single crystal manufacturing apparatus comprising: a magnetic field applying means for applying a magnetic field; and a chamber for accommodating each of the members.

The heater is controlled, and after a lapse of time sufficient for the temperature of the melt to stabilize, the magnetic field applying unit is excited to a desired magnetic field intensity,

And a control means for controlling the heater and the magnetic field applying means as described above.