JPH09110578A - Control of oxygen concentration in silicon single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control, irrespective of pull-up operation time, the oxygen concentrations at the identical growth position within a desired range, for plural rods of silicon single crystal pulled up by conventional or multiple CZ process and differing in pull-up operation time from one another. SOLUTION: In pulling up by conventional or multiple CZ process plural rods of silicon single crystal by use of a pull-up device equipped with a quartz crucible, (1) the relationship between pull-up operation time when pull-up operations are made using the identical device under the identical operational condition and the oxygen concentration at the identical growth position for silicon single crystal is determined with the number of revolutions of the crucible as parameter, (2) the number of revolutions of the crucible is set based on the above relationship and a desired oxygen concentration range at the identical growth position for the silicon single crystal set in advance, and a pull-up operation is conducted using the identical device under the identical operational conditions with those when the above relationship is determined, except for the number of revolutions of the crucible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for pulling a silicon single crystal, and more specifically, a CZ method (Czochralski method),
The present invention relates to a method for controlling oxygen concentration in a silicon single crystal pulled by the multiple CZ method or the continuous charge pulling method.

[0002]

2. Description of the Related Art Conventionally, various methods have been proposed for controlling the oxygen concentration in the production of silicon single crystals by the CZ method. For example, in Japanese Examined Patent Publication No. 60-6911, based on the oxygen concentration profile in the axial direction of a silicon single crystal grown at a constant crucible rotation speed, the inclination of the crucible rotation speed is set so as to have a gradient opposite to that. It is disclosed that the oxygen concentration distribution in the axial direction of the silicon single crystal is controlled within a certain range by controlling the. Also,
Japanese Unexamined Patent Publication No. 64-61383 discloses a method for controlling the oxygen concentration of a single crystal by controlling the flow rate of an inert gas flowing on the liquid surface of the melt in a crucible in a single crystal pulling apparatus. ing.

By the way, recently, as a single crystal pulling method replacing the ordinary CZ method, the multiple CZ method (RCCZ) is used.
Method: Recharge CZ method) or continuous charge pulling method (CCCZ method: Continuous-Charging CZ method) has been developed. The multiple CZ method repeats the operation of refilling the raw material polycrystal and pulling again without solidifying the residual melt in the crucible after the pulling of the silicon single crystal is completed. This is a method of pulling a silicon single crystal. The continuous charge pulling method is to continuously pull the single crystal while keeping the melt amount in the crucible constant by continuously charging the raw material silicon melt or granular polycrystal into the crucible (Fumio Shimura. : "Semiconductor Silicon Crystal Engineering", Maruzen Co., Ltd.).

[0004]

However, the present inventors have found that the multiple CZ method and the continuous charge pulling method have the advantages of improving the raw material yield and the productivity of single crystals, but the CZ method (normal CZ method) is used. Similarly to the above, it was discovered that the oxygen concentration in the silicon single crystal being pulled gradually decreased in the axial direction with the lapse of pulling operation time (the time elapsed immediately after the completion of melting of the polycrystal, the same applies hereinafter). In other words, as the pulling operation time increases, the same equipment
Even when pulled under the same operating conditions, (1) the CZ method and the multiple CZ method have the same growth position (the same position in the axial direction of the silicon single crystal) when a plurality of silicon single crystals having different operating times are compared. Oxygen concentration (Oi)
Decreases with the elapse of the pulling operation time, and (2) in the continuous charge pulling method, the oxygen concentration in the silicon single crystal decreases with the elapse of the pulling operation time, and as a result, the oxygen concentration in the axial direction in the pulled silicon single crystal increases. , It was confirmed that it gradually decreased in the axial direction. The reason why multiple silicon single crystals with different pulling operation time are generated is that the crystal being pulled is melted again due to the dislocation of the crystal, and the crystal is pulled again. And, when pulling a plurality of silicon single crystals from the same quartz crucible, indicate the number of single crystals that have been pulled.), And others.

The present invention is based on the above findings, and its object is, in the CZ method or the multiple CZ method, the oxygen concentration at the same growth position of the pulled silicon single crystal, regardless of the elapse of the pulling operation time. In the continuous charge pulling method, the oxygen concentration distribution in the axial direction in the pulled silicon single crystal is controlled within the desired range regardless of the pulling operation time. is there.

[0006]

A method for controlling an oxygen concentration in a silicon single crystal according to claim 1 is a method for pulling a silicon single crystal by a CZ method using a pulling device equipped with a quartz crucible, 1) The relationship between the pulling operation time and the oxygen concentration at the same growth position in the silicon single crystal when pulling is performed under the same device and the same operating condition,
The rotation speed of the crucible is obtained as a parameter, and (2) the rotation speed of the crucible is set based on a preset desired oxygen concentration range at the same growth position in the silicon single crystal and the relationship between the pulling operation time and the oxygen concentration. At the same time, the conditions other than the rotation speed are increased by setting the same device and the same operation conditions as when the above relationship was obtained.
The oxygen concentration at the same growth position in a silicon single crystal decreases with the lapse of pulling operation time when the crystal being pulled is melted again due to dislocation of the crystal and the crystal is pulled again. It is characterized by suppressing

According to a second aspect of the present invention, there is provided a method for controlling oxygen concentration in a silicon single crystal, wherein a silicon single crystal is subjected to a CZ method by using a pulling apparatus equipped with a quartz crucible and a heater for heating a side wall of the crucible. In the method of pulling up,
(1) The relationship between the pulling operation time and the oxygen concentration at the same growth position in a silicon single crystal when pulling was performed under the same equipment and under the same operating conditions was compared between the upper end of the crucible and the heat generation center of the heater. The vertical separation distance is obtained as a parameter, and (2) the vertical separation distance is determined from the preset desired oxygen concentration range at the same growth position in the silicon single crystal and the relationship between the pulling operation time and the oxygen concentration. The conditions other than the separation distance are set so that the oxygen concentration at the same growth position in the silicon single crystal is changed to cause dislocation, etc. For the reason that the crystal being pulled is melted again for the reason of (1) and the crystal is pulled again, it is possible to suppress the decrease with the lapse of pulling operation time. It is characterized in.

The method for controlling the oxygen concentration in a silicon single crystal according to claim 3 is a method for pulling a silicon single crystal by the multiple CZ method using a pulling device equipped with a quartz crucible, wherein (1) the same device: The relationship between the pulling operation time in the case of pulling under the same operating conditions and the oxygen concentration at the same growth position in the silicon single crystal was obtained by using the rotation speed of the crucible as a parameter, and (2) preset silicon single crystal was used. A desired oxygen concentration range at the same growth position in the crystal is set, and the rotation speed of the crucible is set from the relationship between the pulling operation time and the oxygen concentration, and the conditions other than the rotation speed are the same as when the relationship was obtained. By pulling up under the same equipment and operating conditions, the oxygen concentration at the same growth position in the silicon single crystal may cause the dislocation of the crystal. Ri crystals melt again during pulling, and when again performing pulling of the crystal, in a case where the degree of pulling crystal is different, which comprises suppressing a decrease with the passage of pulling operation time.

According to a fourth aspect of the present invention, there is provided a method for controlling oxygen concentration in a silicon single crystal, wherein a silicon single crystal is subjected to a multiple CZ method by using a pulling apparatus equipped with a quartz crucible and a heater for heating a side wall of the crucible. (1) The relationship between the pulling operation time when pulling is performed under the same equipment and under the same operating conditions and the oxygen concentration at the same growth position in the silicon single crystal, the upper end portion of the crucible and the heater. The vertical distance from the heat generation center of is obtained as a parameter, and (2) the above-mentioned upper and lower sides are selected from the preset desired oxygen concentration range at the same growth position in the silicon single crystal and the relation between the pulling operation time and the oxygen concentration. The separation distance in the direction is set, and the conditions other than the separation distance are set to the same device / operation condition as when the above relationship was obtained. By doing so, when the oxygen concentration at the same growth position in the silicon single crystal causes the crystal under pulling to be melted again for the reason that the crystal has dislocations, etc., and the crystal is pulled up again, or the order of the pulled crystal is different. In the above, it is characterized in that it is suppressed from decreasing with the elapse of the pulling operation time.

The method for controlling the oxygen concentration in a silicon single crystal according to claim 5 is a method for pulling a silicon single crystal by a continuous charge pulling method using a pulling apparatus equipped with a quartz crucible, wherein (1) the same apparatus is used. The relationship between the pulling operation time when pulling is performed under the same operating conditions and the oxygen concentration at the growth position in the silicon single crystal corresponding to the time when the operating time has elapsed is obtained by using the rotation speed of the crucible as a parameter. (2) The relationship between the elapsed time after the start of pulling and the rotation speed of the crucible is set based on the preset desired oxygen concentration range in the axial direction of the silicon single crystal, the pulling operation time, and the oxygen concentration. In addition, the conditions other than the rotation speed were set to the same apparatus and the same operating conditions as when the above relationship was obtained, and the silicon single bond was applied. Oxygen concentration in the pulling axis direction in which is characterized in that suppress deterioration with the passage of pulling operation time.

According to a sixth aspect of the present invention, there is provided a method for controlling oxygen concentration in a silicon single crystal, wherein a silicon single crystal is continuously charged by using a pulling device equipped with a quartz crucible and a heater for heating a side wall of the crucible. In the method of pulling by the method, (1) the relationship between the pulling operation time when pulling is performed under the same equipment and under the same operating conditions, and the oxygen concentration at the growth position in the silicon single crystal corresponding to the time when the operating time has passed. Is calculated using the vertical distance between the upper end of the crucible and the heat generation center of the heater as a parameter, and (2) the preset desired oxygen concentration range in the axial direction of the silicon single crystal, and the pulling operation time. From the relationship with the oxygen concentration, the relationship between the elapsed time after the start of pulling and the vertical distance is set, and the conditions other than the distance are It is characterized in that the pulling is performed under the same apparatus and the same operating conditions as when the above relation is obtained, thereby suppressing the oxygen concentration in the pulling axial direction in the silicon single crystal from decreasing with the lapse of operating time. .

According to the first, third and fifth aspects of the present invention, the decrease in the oxygen concentration in the silicon single crystal when the pulling is performed under the same apparatus and the same operating conditions is compensated for by increasing the crucible rotation speed. To do.

According to the second, fourth, and sixth aspects of the present invention, the decrease in the oxygen concentration in the silicon single crystal when the pulling is performed under the same equipment and the same operating conditions is caused by the upper end of the crucible and the heat generation center of the heater. This is compensated by increasing the vertical separation distance.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The structure and effects of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 1 is a schematic cross-sectional view showing a main part structure of a silicon single crystal pulling apparatus by a CZ method (normal CZ method) or a multiple CZ method. In this pulling apparatus, in a cylindrical chamber 1 made of stainless steel, a crucible 2 having an inner peripheral side made of quartz and an outer peripheral side made of graphite is provided with a support shaft 3 vertically provided.
Supported by. A cylindrical heater 4 made of a carbon material is arranged around the crucible 2.
A cylindrical heat insulating material 5 also made of a carbon material is provided around the. The support shaft 3 (and thus the crucible 2) can be rotated by a rotary drive device (not shown) having a control mechanism, and the number of rotations can be finely adjusted. The heater 4 has a control mechanism and can be moved up and down by a slide mechanism (not shown), and its vertical position can be finely adjusted.

A cylindrical pull chamber 6 made of stainless steel is concentrically connected to the chamber 1 above the chamber 1, and an isolation valve 7 is provided at a connecting portion between the chamber 1 and the pull chamber 6. Has been deployed. The pull chamber 6 accommodates the pulled silicon single crystal and forms a space for taking it out to the outside. A silicon single crystal winding device (not shown) is arranged above the pull chamber 6 so as to be rotatable about a vertical axis. A wire 8 is hung from the winding device, and a seed crystal 10 is attached to the lower end of the wire 8 by a seed holding jig 9. A supply port 11 for an inert gas such as Ar is provided above the pull chamber 6.
However, an exhaust port 12 for the inert gas is provided at the bottom of the chamber 1. The exhaust port 12 is connected to a vacuum generator (not shown) so that the chamber 1 and the pull chamber 6 can be maintained at a predetermined vacuum degree.

Embodiment 2 FIG. 2 is a schematic cross-sectional view showing the main structure of a silicon single crystal pulling apparatus by the continuous charge pulling method. In the chamber 1 of this apparatus, an apparatus for enabling the pulling of the silicon single crystal by the continuous charge pulling method is provided. Other configurations are similar to those of the apparatus shown in FIG. That is, a quartz cylindrical partition wall 21 having an outer diameter smaller than the inner diameter of the crucible 2 is provided concentrically with the crucible 2, and a supply device 31 of granular polycrystalline silicon is provided above the chamber 1 above the chamber 1.
Is provided. The supply device 31 includes a container 32 of granular polycrystalline silicon 41, a vibration feeder 33 connected to the lower end portion of the container 32, a closed chamber (with an opening / closing lid) 34 for accommodating the container 32 and the vibration feeder 33 in a closed state, A quartz supply pipe 35 connected to the outlet of the vibration feeder 33 is provided. Supply pipe 35
The lower half part of the is inserted into the chamber 1, and the lower end part thereof is inserted into the gap between the crucible 2 and the partition wall 21. A supply port 3 for an inert gas such as Ar gas is provided above the closed chamber 34.
4a, and an inert gas exhaust port 34b is opened at the bottom. 1 and 2, 51 is a silicon melt, and 52 is a silicon single crystal in the process of pulling.

[Test Example 1] Next, a pulling test of a silicon single crystal by the CZ method (normal CZ method) performed using the pulling apparatus of FIG. 1 will be described. First, pulling crystal N
o. In 1 (first batch of crystals), by driving the vacuum generator and supplying an inert gas,
The pressure in the chamber 1 and the pull chamber 6 is set to 10
It was kept at 0 mbar. In this state, the polycrystalline silicon charged in advance in the crucible 2 was melted by the heater 4. Next, the seed crystal 10 at the lower end of the wire 8 was immersed in the surface of the silicon melt 51 in the crucible 2, the crucible 2 was rotated at R ₁ rpm, and the wire 8 was pulled up at a predetermined speed while rotating. By the above operation, the diameter D
A silicon single crystal having i inches and a total length of Li inches was manufactured. The pulling time for pulling the center of this crystal is Ti
Met.

Pulled crystal No. 2 (2nd batch of crystals)
Is a pulled crystal No. Under the same conditions as in No. 1, a silicon single crystal having the same size as that of No. 1 was manufactured. However, after the polycrystalline silicon was melted, the single crystal was pulled up after standing for a certain period of time. This pulled crystal No. The pulling up time in the center of No. ₂ was T ₂ . Further, the pulled crystal No. 3 ~
No. Crystal No. 5 was pulled up. Under the same conditions as in No. 1, a silicon single crystal having the same size as that of No. 1 was manufactured. Pulled crystal N
o. 1 to No. _No. 5 is different in the standing time after melting the polycrystalline silicon, and in the following test, the pulling operation time when pulling the central portion of the single crystal straight body was T ₁ <T ₂ <T ₃ <T ₄ <T
₅ (the number indicates the crystal No.).

[Test Example 2] Next, a pulling test of a silicon single crystal by the multiple CZ method performed using the pulling apparatus of FIG. 1 will be described. First, the pulled crystal No.
In No. 11 (the crystal pulled up in the first batch of the first batch), the vacuum generator was driven and an inert gas was supplied to the inside of the chamber 1 and the pull chamber 6.
The pressure inside was maintained at 100 mbar. In this state, the polycrystalline silicon charged in advance in the crucible 2 was melted by the heater 4. Next, on the surface of the silicon melt 51 in the crucible 2, the seed crystal 10 at the lower end of the wire 8 is
Was dipped, the crucible 2 was rotated at R ₁ rpm, and the wire 8 was pulled up at a predetermined speed while rotating. By the above operation, a silicon single crystal having a diameter of Di inch and a total length of Li inch was manufactured.

Pulled crystal No. No. 12 (the crystal pulled up in the second batch of the first batch), the silicon remaining in the crucible 2 is maintained in a molten state, and in this state, the polycrystalline silicon 41
Is additionally charged into the crucible 2 and the liquid level of the melt in the crucible 2 is pulled up to crystal No. 2. The same as No. 11 and the pulling crystal No.
Under the same conditions as for No. 11, the pulled crystal No. Do 12 steps,
Pulled crystal No. A silicon single crystal having the same size as 11 was manufactured. Further, the pulled crystal No. By repeating the same operation as in No. 12, the pulled crystal No. The operations of Nos. 13 to 15 were performed to pull up the crystal No. A silicon single crystal having the same size as 11 was manufactured.

Next, the rotation speed of the crucible 2 is changed from R ₁ to R.
₂ (However, R ₂ > R ₁ )
o. Under the same conditions as in No. 11, the pulled crystal No. 21-25
(The crystals of the first batch to the fifth batch of the second batch) were operated, and the rotation speed of the crucible 2 was changed to R ₃ ,
The pulled crystal Nos. Were changed to R ₄ and R ₅ (provided that R ₅ > R ₄ > R ₃ > R ₂ ). Under the same conditions as in No. 11, the pulled crystal No. 31-35, 41-45, 51-55 (the crystals of the 3rd, 4th, and 5th batches, and the crystals that were pulled up to the 1st to 5th lines, respectively), and the pulled crystal No. A silicon single crystal having the same size as 11 was manufactured.

The CZ method thus obtained (normal CZ
Method) 5 silicon single crystals and multiple C
With respect to 25 silicon single crystals by the Z method, the oxygen concentration Oic in the central portion (in the vicinity of the center of gravity of the straight body portion) in the axial direction and the diametrical direction was measured. The results are as shown in FIGS. 3 and 4, and oxygen concentration change curves l ₁₀ (FIG. 3) and l _{11 to} l ₁₅ (FIG. 4) with the number of rotations of the crucible 2 as a parameter were obtained. That is, FIGS. 3 and 4 show pulling crystal Nos. Of a plurality of silicon single crystals having different pulling operation times. And the oxygen concentration at the same growth position were obtained using the rotation speed of the crucible as a parameter. From the slopes of l _{10 in} FIG. 3 and l ₁₁ in FIG. 4, the relationship between the pulling operation time and the reduction rate of the oxygen concentration in the silicon single crystal is the same between the CZ method (normal CZ method) and the multiple method. Was confirmed.
Further, from FIGS. 3 and 4, (1) when the rotation speed of the crucible 2 is constant, the oxygen concentration Oic decreases as the crystal is pulled up later (that is, as the pulling operation time elapses), (2) When comparing single crystals having different pulling operation times and different pulling batches, it was found that the oxygen concentration Oic increased as the rotation speed of the crucible 2 increased.

Therefore, the target oxygen concentration is Oit (p
pma), in the graph of FIG. 4, a straight line L passing through the point of “Oit” on the vertical axis and parallel to the horizontal axis is drawn, and this straight line L and each pulled crystal No. Of the crucible rotation speed r _{1 to} r ₅ (where r ₅ > r ₄ > r ₃ > r _{2 of the} oxygen concentration change curve that passes through an intersection with a straight line parallel to the vertical axis.
> R ₁ ), each pulled crystal No. When the crucible rotation number is set to r ₁ to r ₅ in the operation of No. 3, each pulling crystal No. The oxygen concentration Oic of the silicon single crystal obtained in
It can be close to it. In the case where the oxygen concentration variation curve passing through the intersection as described above does not exist, the oxygen concentration variation curve l ₁₁ to l ₁₅ by interpolating or extrapolating, may be obtained an approximation of the desired crucible rotation speed.

"Pulled-up crystal No. 3" obtained in the above manner
FIG. 5 shows the relationship between “and desired crucible rotation speed”. That is, FIG. 5 is a graph showing the oxygen concentration control method in the silicon single crystal prepared based on FIG. 4, in which the oxygen concentration at the same growth position is desired for a plurality of silicon single crystals having different pulling operation times. In the case of controlling within the range of the pulling crystal No. of the silicon single crystal. 3 shows the relationship with the set value of the number of rotations of the crucible in the pulling operation time of.

Next, the rotation speed of the crucible 2 was set as shown in FIG. No. 11 pulling crystal No. 11 61-65, and pulling crystal No. A silicon single crystal having the same size as 11 was manufactured. The oxygen concentration Oic was measured for five silicon single crystals having different pulling operation times. The results are as shown in FIG. 5, and the oxygen concentration Oic is almost the target value Oit ±
It could be controlled within the range of 1.0 (ppma ASTM'79, the same applies hereinafter).

[Test Example 3] In Test Example 2, the relationship between the number of rotations of the crucible 2 and the oxygen concentration Oic was examined. In Test Example 3, the pulling crystal Nos. For a plurality of silicon single crystals were examined. And the oxygen concentration at the same growth position were obtained using the vertical distance D (see FIG. 1) between the upper end of the crucible 2 and the heat generation center Hc of the heater 4 as a parameter. In this case, all the pulled crystal Nos. And the number of rotations of the crucible 2 was set to R rpm, and the pulling crystal No. by the CZ method (normal CZ method) was used. In Nos. 101 to 105, the separation distance D was set to D ₁ and the pulled crystal No. ₁ by the multiple CZ method was used. 111-115
Then, the separation distance D is set to D ₁ , and the pulled crystal No. 121 ~ 1
In No. 25, the separation distance D is set to D ₂ , and the pulled crystal No. 131
˜135, the separation distance D was set to D ₃ and the pulled crystal No. 1
41 to 145, the separation distance D is set to D ₄ , and the pulled crystal N
o. The distance D in the 151 to 155 to the D _5, respectively set _{(although, D 5> D 4> D} 3> D 2>
D ₁ ), other operating conditions were the same as in Test Example 1, and five silicon single crystals having a diameter of Di inch and a total length of Li inch were manufactured by the CZ method (normal CZ method) and 25 by the multiple CZ method. In this case, the distance D was adjusted by moving the heater 4 in the vertical direction by the slide mechanism.

The CZ method thus obtained (usually CZ
Oxygen concentration Oi in the vicinity of the center of gravity of the straight body part for five silicon single crystals
c was measured. The results are shown in FIGS. 6 and 7, and the oxygen concentration change curve l ₂₀ (FIG. 6) and l _{21 to} l ₂₅ (FIG. 7) using the separation distance as a parameter were obtained. That is, FIGS. 6 and 7 show pulling crystal Nos. Of a plurality of silicon single crystals having different pulling operation times. And the oxygen concentration at the same growth position are obtained by using the separation distance as a parameter. From the slopes of l _{20 in} FIG. 6 and l ₂₁ in FIG. 7, the relationship between the pulling operation time and the reduction rate of the oxygen concentration in the silicon single crystal is the same between the CZ method (normal CZ method) and the multiple method. Was confirmed. Further, from FIGS. 6 and 7, (1) when the separation distance is constant, the oxygen concentration Oic decreases as the crystal is pulled up later (that is, as the pulling operation time elapses), and (2) pulling operation time It was found that the oxygen concentration Oic increased as the separation distance was longer, by comparing the silicon single crystals having the same course of the above and different pulling batches.

Therefore, the target oxygen concentration is Oit (p
pma), in the graph of FIG. 7, a straight line L passing through the point of “Oit” on the vertical axis and parallel to the horizontal axis is drawn, and this straight line L and each pulled crystal No. Distances d _{1 to} d ₅ (where d ₅ > d ₄ > d ₃ > d ₂ > d) of the oxygen concentration change curve that passes through the intersection with a straight line parallel to the vertical axis.
₁ ) is calculated, and each pulled crystal No. If the operations by setting the distance to d ₁ to d _5, the pulling crystal No. The oxygen concentration Oic of the silicon single crystal obtained in step 1 can be set to a value close to Oit. If there is no oxygen concentration change curve passing through the above-mentioned intersection, the desired approximate distance distance may be obtained by interpolating or extrapolating the oxygen concentration change curves l _{21 to} l ₂₅ .

FIG. 8 shows the "relationship between the pulled crystal No. and the desired separation distance" obtained by the above procedure. That is, FIG. 8 is a graph showing a method for controlling the oxygen concentration in a silicon single crystal, which is created based on FIG. 7, and controls the oxygen concentration at the same growth position within a desired range for a plurality of silicon single crystals. In the case of the pulling crystal No.
And the crystal No. 3 shows the relationship with the set value of the separation distance in FIG.

Next, the separation distance is set as shown in FIG. 8, and the other conditions are the pulled crystal No. The same as No. 111, the pulled crystal No. 161-165,
Pulled crystal No. A silicon single crystal having the same size as 111 was manufactured. The oxygen concentration Oic was measured for five silicon single crystals having different pulling operation times. The results are as shown in FIG. 8, and the oxygen concentration Oic is almost the target value Oit.
It could be controlled within the range of ± 1.0 (ppma).

[Test Example 4] FIG. 2 is a schematic cross-sectional view showing a main structure of a silicon single crystal pulling apparatus by a continuous charge pulling method. An example of a pulling test of a silicon single crystal conducted using this apparatus will be described. First, in the same manner as in Test Example 1, the rotational speed of the crucible 2 was set to R _{11 to} R ₁₅ (provided that R ₁₅ >
R ₁₄ > R ₁₃ > R ₁₂ > R ₁₁ ) was changed in five ways, and the other operating conditions were set the same, and a total of 5 silicon single crystals with a diameter of Di inches and a total length of Li inches were produced. Thus, the relationship between the pulling operation time and the oxygen concentration Oi at the growth position in the silicon single crystal corresponding to the time when the operation time has elapsed was obtained using the rotation speed of the crucible 2 as a parameter. This is shown in FIG. The amount of melt in the crucible 2 was controlled to be constant by continuously charging the polycrystalline silicon 41 during the pulling operation. The pressure inside the chamber 1 and the pull chamber 6 is 100 mb, as in the first embodiment.
maintained at ar.

Next, in the same manner as in Test Example 1, as shown in FIG. 10 from the graph of FIG. 9, the relationship between the elapsed time after the start of pulling and the crucible rotation speeds r _{11 to} r ₁₅ is set (however,
r ₁₅ > r ₁₄ > ₁₃ > r ₁₂ > r ₁₁ and the crucible rotation speed increases as the elapsed time increases. ),
With respect to the conditions other than the rotation speed, the pulling operation was performed under the same operating conditions as when the above relationship was obtained. As a result, as shown in FIG. 10, the oxygen concentration Oic is almost equal to the target value Oit ±.
It was possible to control within the range of 1.0 (ppma).

[Test Example 5] Another example of the pulling test of the silicon single crystal by the continuous charge pulling method, which was carried out by using the pulling apparatus shown in FIG. 2, will be described. In this case, all the pulled crystal Nos. And the rotation speed of the crucible 2 is R rpm, and the separation distance is D _{11 to} D ₁₅ (where D ₁₅ > D ₁₄ > D ₁₃ >).
D ₁₂ > D ₁₁ ), the other operating conditions were set to be the same as in Test Example 4, and a total of 5 silicon single crystals having a diameter of Di inches and a total length of Li inches were manufactured. Thus, the relationship between the pulling operation time and the oxygen concentration Oi at the growth position in the silicon single crystal corresponding to the time when the operation time has elapsed was obtained using the separation distance as a parameter. This is shown in FIG. During the pulling operation, the polycrystalline silicon 41
Was continuously charged to control the melt amount in the crucible 2 to be constant. The pressure inside the chamber 1 and the pull chamber 6 is 100 mbar as in the first embodiment.
Maintained.

Then, in the same manner as in Test Example 1, the relationship between the elapsed time after the start of pulling and the distances d _{11 to} d ₁₅ is set from the graph of FIG. 11 (however, d
_15> d _14> d _13> a d _12> d _11, to increase the distance according to the elapsed time becomes longer. ), The conditions other than the separation distance were raised under the same operating conditions as when the above relationship was obtained. As a result, as also shown in FIG. 12, the oxygen concentration Oic is almost the target value Oit ± 1.0.
It was possible to control within the range of (ppma).

[0035]

As is apparent from the above description, in the inventions described in claims 1, 3 and 5, it is possible to reduce the oxygen concentration in the silicon single crystal when the pulling is performed under the same apparatus and the same operating conditions. Since the compensation is performed by increasing the number of rotations of the crucible, in the CZ method or the multiple CZ method, the oxygen concentration at the same growth position of the pulled silicon single crystal is desired regardless of the length of pulling operation time. The continuous charge pulling method can control the oxygen concentration distribution in the axial direction of the pulled silicon single crystal within a desired range regardless of the length of pulling operation time. Becomes Further, claim 2,
In the inventions of Nos. 4 and 6, the decrease of the oxygen concentration in the silicon single crystal when the pulling is carried out under the same apparatus and the same operating condition is
Since the compensation is made by increasing the vertical distance between the upper end of the crucible and the heat generation center of the heater, the pulling by the CZ method, the multiple CZ method or the continuous charge pulling method is performed. The same excellent effect can be obtained.

[Brief description of the drawings]

FIG. 1 relates to the first embodiment of the present invention and is a schematic cross-sectional view showing a main part structure of a silicon single crystal pulling apparatus by a CZ method (normal CZ method) or a multiple CZ method.

FIG. 2 relates to the second embodiment of the present invention and is a schematic cross-sectional view showing a main part structure of a silicon single crystal pulling apparatus by a continuous charge pulling method.

FIG. 3 is a graph showing the results of Test Examples 1 and 2.

FIG. 4 is a graph showing the results of Test Examples 1 and 2.

FIG. 5 is a graph showing the method for controlling the oxygen concentration in the silicon single crystal of the present invention, which was created based on FIG.

FIG. 6 is a graph showing the results of Test Example 3.

FIG. 7 is a graph showing the results of Test Example 3.

FIG. 8 is a graph showing the method for controlling the oxygen concentration in the silicon single crystal of the present invention, which was created based on FIG. 7.

FIG. 9 is a graph showing the results of Test Example 4.

FIG. 10 is a graph showing the method for controlling the oxygen concentration in the silicon single crystal of the present invention, which was created based on FIG. 9.

FIG. 11 is a graph showing the results of Test Example 5.

FIG. 12 is a graph showing the method for controlling the oxygen concentration in the silicon single crystal of the present invention, which was created based on FIG. 11.

[Explanation of symbols]

 1 Chamber 2 Crucible 3 Support Shaft 4 Heater 5 Heat Insulating Material 6 Pull Chamber 7 Isolation Valve 8 Wire 9 Species Holding Jig 10 Species Crystal 11,34a Inert Gas Supply Port 12,34b Inert Gas Exhaust Port 21 Partition Wall 31 Polycrystalline Silicon Supply Device 32 Container 33 Vibration Feeder 34 Closed Chamber 35 Supply Pipe 41 Polycrystalline Silicon 51 Silicon Melt 52 Silicon Single Crystal

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Atsushi Iwasaki 2-13-50 Kitafu, Takefu City, Fukui Prefecture Shin-Etsu Semiconductor Co., Ltd. Takefu Factory

Claims (6)

[Claims] 1. A method for pulling a silicon single crystal by a CZ method using a pulling apparatus having a quartz crucible, (1) a pulling operation time when pulling is performed under the same apparatus and under the same operating conditions, The relationship with the oxygen concentration at the same growth position in the silicon single crystal was obtained using the number of rotations of the crucible as a parameter, and (2) the desired oxygen concentration range at the same growth position in the silicon single crystal, which was set in advance, and the pulling operation. While setting the rotation speed of the crucible from the relationship between time and oxygen concentration, the conditions other than the rotation speed, in the silicon single crystal by pulling up as the same device and the same operating conditions as when the relationship was obtained. The oxygen concentration in the silicon single crystal is characterized by suppressing the decrease of the oxygen concentration at the same growth position with the lapse of pulling operation time. Control method. 2. A method for pulling a silicon single crystal by the CZ method using a pulling device equipped with a quartz crucible and a heater for heating the side wall of the crucible, comprising: (1) under the same device and under the same operating conditions. The relationship between the pulling operation time when pulling is performed and the oxygen concentration at the same growth position in the silicon single crystal, is obtained by using the vertical distance between the upper end of the crucible and the heat generation center of the heater as a parameter, 2) The preset distance is set based on a preset desired oxygen concentration range at the same growth position in the silicon single crystal and the relationship between the pulling operation time and the oxygen concentration. , The oxygen concentration at the same growth position in the silicon single crystal was increased by pulling under the same equipment and the same operating conditions as when the above relationship was obtained. Oxygen concentration control method of a silicon single crystal, characterized in that to suppress a decrease with the passage of raising operating hours. 3. A method of pulling a silicon single crystal by a multiple CZ method using a pulling device equipped with a quartz crucible, comprising: (1) pulling operation time when pulling is performed under the same device and under the same operating conditions. The relationship between the oxygen concentration at the same growth position in the silicon single crystal is obtained by using the number of rotations of the crucible as a parameter, and (2) the preset desired oxygen concentration range at the same growth position in the silicon single crystal and the pulling rate are set. The rotation speed of the crucible is set from the relationship between the operating time and the oxygen concentration, and the conditions other than the rotation speed are the same apparatus and the same operating conditions as when the above relationship was obtained, and the silicon single crystal is pulled up. Silicon single crystal characterized by suppressing the decrease of oxygen concentration at the same growth position in the steel with the elapse of pulling operation time Oxygen concentration control method of. 4. A method for pulling a silicon single crystal by the multiple CZ method using a pulling device equipped with a quartz crucible and a heater for heating the side wall of the crucible, comprising: (1) the same device under the same operating conditions. The pulling operation time when pulling in, and the relationship between the oxygen concentration at the same growth position in the silicon single crystal, the vertical separation distance between the upper end of the crucible and the heat generation center of the heater, as a parameter, (2) The preset distance is set in advance from the desired oxygen concentration range at the same growth position in the silicon single crystal and the relationship between the pulling operation time and the oxygen concentration, and conditions other than the distance are set. By pulling under the same equipment and same operating conditions as when the above relation was obtained, the same growth position in the silicon single crystal Oxygen concentration control method of a silicon single crystal, wherein a hydrogen concentration to suppress a decrease with the passage of pulling operation time. 5. A method of pulling a silicon single crystal by a continuous charge pulling method using a pulling apparatus equipped with a quartz crucible, (1) Pulling operation time when pulling is performed under the same equipment and under the same operating conditions. And the oxygen concentration at the growth position in the silicon single crystal corresponding to the time when the operation time has elapsed, using the rotation speed of the crucible as a parameter, and (2) preset axial direction of the silicon single crystal. From the relationship between the desired oxygen concentration range, the pulling operation time and the oxygen concentration, the relationship between the elapsed time after the start of pulling and the rotation speed of the crucible is set, and conditions other than the rotation speed are determined by the relationship. By performing pulling under the same equipment and operating conditions as in the above case, the oxygen concentration in the pulling axial direction in the silicon single crystal can be adjusted by the pulling operation time. Oxygen concentration control method of a silicon single crystal, characterized in that suppress deterioration me. 6. A method for pulling a silicon single crystal by a continuous charge pulling method using a pulling apparatus equipped with a quartz crucible and a heater for heating a side wall of the crucible, comprising: (1) the same apparatus and the same operating conditions. The relationship between the pulling operation time when the pulling is performed below and the oxygen concentration at the growth position in the silicon single crystal corresponding to the time when the operating time has passed, between the upper end of the crucible and the heat generation center of the heater. From the relationship between the preset desired oxygen concentration range in the axial direction of the silicon single crystal, the pulling operation time and the oxygen concentration, which are set in advance as the parameter, the vertical distance is used as a parameter, and the elapsed time after the start of pulling and the above The relationship with the vertical separation distance is set, and the conditions other than the separation distance are the same device / same operating conditions as when the above relationship was obtained. By performing up, the oxygen concentration control method of a silicon single crystal, characterized in that the oxygen concentration of the pulling axis direction in the silicon single crystal to suppress a decrease with the passage of operation time.