JP5145176B2 - Silicon single crystal pulling apparatus and silicon single crystal pulling method - Google Patents

Description

  The present invention relates to a silicon single crystal pulling apparatus and a silicon single crystal pulling method, and in particular, a silicon single crystal pulling apparatus and a silicon single crystal pulling method in which the oxygen concentration of the silicon single crystal is high and the in-plane oxygen concentration distribution is uniform. It is about the method.

  In recent years, with changes in the device formation process, a standardized silicon wafer with a high oxygen concentration has been demanded in order to prevent dislocations and warpage due to increased stress during device formation. It is generally known that the strength of silicon increases when oxygen is mixed.

  In the crystal growth by the CZ (Czochralski) method, the amount of oxygen dissolved from the quartz crucible decreases as the contact area between the quartz crucible and the silicon melt decreases in the latter half of the crystal, and the oxygen concentration decreases as the latter half of the crystal. The phenomenon is generally known. Therefore, there is a problem that the oxygen concentration is out of specification in the latter half of the crystal and the yield is lowered.

  Therefore, Patent Document 1 discloses a technique for applying a lateral (horizontal) magnetic field to increase the rotation speed of a quartz crucible as in the conventional CZ method so as to increase oxygen. However, in Patent Document 1, if the rotation speed of the quartz crucible is increased, a problem of deformation or polycrystallization of the silicon single crystal occurs (see Patent Document 1).

  Further, in Patent Document 2, in the lateral magnetic field applied CZ method (Horizontal Magnetic Field Applied Czochralski, hereinafter referred to as “HMCZ method” in some cases), the flow from the quartz crucible bottom is activated by lowering the magnetic field position. A method for easily obtaining crystals having an oxygen concentration is disclosed. However, this method of lowering the magnetic field position has a problem that the flow from the bottom of the quartz crucible is activated and it becomes easy to obtain a crystal having a high oxygen concentration, while the in-plane oxygen concentration distribution is remarkably deteriorated. The deterioration of the in-plane oxygen concentration distribution leads to a situation where the standard is not met, and the yield is lowered.

  Therefore, in the above method, as a method of improving the yield reduction, the magnetic field strength is increased toward the latter half of the crystal, and the viscosity of the silicon melt is increased to increase the friction between the silicon melt and the quartz crucible, and the amount of oxygen dissolved A method of increasing the value can be considered. However, with this method of increasing the magnetic field strength in the second half of the crystal, even if the magnetic field strength is increased at a certain level or higher, the increase in viscosity due to the magnetic field has reached its peak, and the oxygen concentration does not increase. A silicon crystal cannot be obtained.

  As described above, the in-plane oxygen concentration distribution deteriorates due to the change in the magnetic field position. On the other hand, depending on the method of increasing the magnetic field strength, the increase in viscosity due to the magnetic field reaches a peak, and a desired oxygen concentration cannot be obtained. Therefore, in order to obtain a high oxygen concentration silicon crystal by increasing the oxygen concentration in the latter half of the crystal, it is necessary to make the in-plane oxygen concentration distribution uniform while lowering the magnetic field position.

  Therefore, the present inventors considered the reason why the in-plane oxygen concentration becomes non-uniform when the magnetic field position is lowered. Then, when the magnetic field position was lowered, the flow from the quartz crucible bottom was activated as described above, and it was thought that the inhomogeneity of oxygen dissolution at the quartz crucible bottom would affect the silicon crystal. That is, the flow of the silicon melt takes in the non-uniformity of oxygen dissolution at the bottom of the quartz crucible, and the flow of the silicon melt including the high oxygen concentration region and the flow of the silicon melt including the low oxygen concentration region replace each other. I thought that it became non-uniform in the crystal length direction.

Therefore, it was thought that by improving the non-uniformity of oxygen dissolution at the bottom of the quartz crucible, a silicon single crystal having a uniform in-plane oxygen concentration distribution and a high oxygen concentration can be obtained.
JP 2004-189557 A JP 2004-182560 A

  In the second half of the crystal of the lateral magnetic field application CZ method, the present invention lowers the magnetic field center position and the heater position simultaneously from the surface of the silicon melt, thereby maintaining the oxygen concentration of the silicon single crystal high and maintaining the in-plane oxygen concentration. An object of the present invention is to provide a silicon single crystal pulling apparatus and a silicon single crystal pulling method capable of making the above uniform.

According to an embodiment of the present invention, a crucible composed of a quartz crucible and a graphite crucible that melts silicon into a silicon melt, a crucible rotation drive unit that moves up and down while rotating the crucible, and a means for melting the silicon A heater that is a heat generation source, a heater drive unit that raises and lowers the heater, a magnetic field application unit that applies a magnetic field to the silicon melt, a magnetic field drive unit that raises and lowers the magnetic field application unit, and the crucible rotation A driving unit, connected to the heater driving unit and the magnetic field driving unit, and a controller for controlling the driving of the crucible rotation driving unit, the heater driving unit and the magnetic field driving unit, the control unit, in synchronization with the vertical movement of the crucible by the crucible rotation driving unit, and the depth of the silicon melt is B, the vertical direction of the lower surface of the silicon melt in the quartz crucible (minimum surface) Position and L, when referred to this L to seed the crystal side +, the magnetic field center position of the magnetic field applying unit + 1 / 2B + L~ + 1 / 3B + the controls the driving of the magnetic field driving unit so as to be located in L Driving the heater based on data obtained by heat transfer analysis of the surface of the silicon melt and the quartz crucible wall so that the temperature of the silicon melt is always uniform at the same time A case where the upper end of the graphite crucible is in an upper position with respect to the upper end of the heater with reference to a position where the upper end of the heater and the upper end of the graphite crucible are matched by controlling the drive of the unit + when the side, the silicon single crystal pulling apparatus according to claim Rukoto tracking is as the upper end of the graphite crucible is + 20 mm above + 100 mm or less is provided.

According to one embodiment of the present invention, in a silicon single crystal pulling method for pulling a silicon single crystal from a silicon melt in a quartz crucible while applying a transverse magnetic field by a magnetic field applying unit, the quartz single crystal is pulled along with the pulling of the silicon single crystal. The crucible is moved up and down while the depth of the silicon melt is B, the vertical position of the lower surface (lowest surface) of the silicon melt in the quartz crucible is L, and the seed crystal is based on this L. When the side is defined as +, the magnetic field application unit is moved up and down so that the magnetic field center position of the magnetic field application unit is located in + 1 / 2B + L to + 1 / 3B + L, and synchronized with the raising and lowering of the quartz crucible and the magnetic field application unit. based on the data obtained by heat transfer analysis of the surface and the quartz crucible wall in advance the silicon melt so as to maintain a uniform temperature of the silicon melt Based on the serial was a silicon melt in the quartz crucible is moved up and down the heater for heating matching the upper ends and the graphite crucible of the heater position, a position upper end of an upper side of the graphite crucible than an upper end of the heater There is provided a method for pulling a silicon single crystal characterized by causing the graphite crucible to follow an upper end of +20 mm or more and +100 mm or less when a certain case is set to the + side .

  According to the present invention, in the second half of the crystal in the lateral magnetic field application CZ method, the magnetic field center position and the heater position are simultaneously lowered from the surface of the silicon melt, thereby maintaining the oxygen concentration of the silicon single crystal high, It is possible to provide a silicon single crystal pulling apparatus and a silicon single crystal pulling method that can make the oxygen concentration uniform.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiment. Moreover, in each embodiment, the same code | symbol is attached | subjected about the same structure and it may not explain anew.

  In the embodiment of the present invention, it is assumed that the non-uniformity of oxygen penetration from the bottom of the quartz crucible is determined by the temperature of the bottom of the quartz crucible and the friction between the silicon melt and the bottom of the quartz crucible. Paying attention to the distribution, heat transfer analysis of the temperature of silicon melt and quartz crucible wall was conducted. As a result, the inventors have found that the more uniform the temperature difference at the contact surface between the quartz crucible and the silicon melt, the better the in-plane oxygen concentration distribution, and the present invention has been created. Hereinafter, description will be made based on the drawings.

  FIG. 1 is a schematic sectional view showing a silicon single crystal pulling apparatus 100 according to an embodiment of the present invention. As shown in FIG. 1, a silicon single crystal pulling apparatus 100 according to an embodiment of the present invention includes a furnace body 120 formed by superposing a pull chamber 122 on a cylindrical main chamber 121, and a furnace body 120 interior. And a heater 142 for maintaining the temperature of the silicon melt 116 loaded in the crucible 130. Around the heater 142, a first heat retaining member 145, a second heat retaining member 146, and a third heat retaining member 147 are provided along the inner wall of the main chamber 121 in order to effectively apply the heat of the heater 142 to the crucible 130. Is provided. The crucible 130 has a double structure, and the inner side is constituted by a quartz crucible 131 and the outer side is constituted by a graphite crucible 132.

  Above the furnace body 120, a winding mechanism 110 for winding the silicon single crystal 115 is provided. The winding mechanism 110 includes a winding unit 111 that winds up the wire 113 that winds up the silicon single crystal 115, and a motor that has a motor therein, and a wire rotation drive that applies a driving force for winding the wire 113 to the winding unit 111. A portion 112 and a pulling wire 113 wound around the winding portion 111 are configured. A seed crystal 114 is attached to the tip of the wire 113 and is arranged to be pulled up while growing the silicon single crystal 115.

  In the main chamber 121, upper and lower portions are formed above and in the vicinity of the crucible 130, and a radiation shield 144 is provided to prevent the silicon single crystal 115 being grown from being given excessive radiant heat from the heater 142. Is provided.

  Although not shown, the radiation shield 144 is configured to be movable up and down by winding and unwinding the wire 113 (lifting means) by a lifting drive unit (lifting means). That is, when the silicon is melted, the radiation shield 144 is disposed above the crucible 130 and is pulled down so that the lower end thereof is positioned in the crucible 130 as the silicon single crystal 115 is pulled up. The radiation shield 144 includes a second heat retaining member 146 (supporting means) provided on the first heat retaining member 145 and a third heat retaining member 147 provided on the second heat retaining member 146. Mounted and supported. Here, since the distance between the lower end of the radiation shield 144 and the surface of the silicon melt 116 is an important parameter for the crystal characteristics of silicon, the lower end of the radiation shield 144 and the silicon melt 116 are reduced as the silicon melt 116 decreases. The radiation shield 144 and the crucible 130 are arranged so as to be able to be raised and lowered so that the distance from the surface is constant.

  Furthermore, the silicon single crystal pulling apparatus 100 according to the embodiment of the present invention includes a magnetic field applying unit 140. The magnetic field application unit 140 is connected to the magnetic field driving unit 141, and the magnetic field driving unit 141 is connected to the control unit 160. The magnetic field driving unit 141 moves the magnetic field applying unit 140 up and down so that the magnetic field center position of the magnetic field applying unit 140 is located below the surface of the silicon melt 116 under the control of the control unit 160. In this way, by locating the magnetic field center position of the magnetic field application unit 140 below the surface of the silicon melt 116, the flow from the bottom of the quartz crucible 130 is activated, and crystals with a high oxygen concentration are easily obtained.

  Furthermore, the silicon single crystal pulling apparatus 100 according to the embodiment of the present invention includes a heater 142. The heater 142 is connected to the heater driving unit 143, and the heater driving unit 143 is connected to the control unit 160. The heater 142 can be moved up and down in accordance with the growth stage of the silicon single crystal 115 by the heater driving unit 143 controlled by the control unit 160. The heater 142 is arranged to make the temperature of the silicon melt 116 in the quartz crucible 131 uniform. This is because by making the temperature of the silicon melt 116 uniform, the in-plane oxygen concentration distribution can be made uniform.

  Furthermore, the silicon single crystal pulling apparatus 100 according to the embodiment of the present invention includes a crucible rotation driving unit 150. The crucible rotation drive unit 150 includes a table 117 and a rotation shaft 118. The crucible rotation drive unit 150 is a drive unit for rotating and raising and lowering the crucible 130 in a predetermined direction of the rotation shaft 118.

  Furthermore, the silicon single crystal pulling apparatus 100 according to the embodiment of the present invention includes a control unit 160. The control unit 160 controls the raising / lowering operations of the magnetic field driving unit 141, the heater driving unit 143, and the crucible rotation driving unit 150 described above. Therefore, in order to appropriately control the raising / lowering operations of the magnetic field driving unit 141, the heater driving unit 143, and the crucible rotation driving unit 150 by the control unit 160, paying attention to the temperature distribution in the quartz crucible 131, the silicon melt 116 and the quartz The heat transfer analysis of the temperature of the crucible 131 wall was performed. In the silicon single crystal pulling apparatus 100 according to the embodiment of the present invention, the result of the heat transfer analysis described above is stored in the control unit 160, and the magnetic field application is performed in synchronization with the raising and lowering of the crucible 130 by the crucible rotation driving unit 150. The magnetic field applying unit 140 is moved up and down by controlling the driving of the magnetic field driving unit 141 so that the magnetic field center position of the unit 140 is always located at a predetermined position from the surface of the silicon melt 116. At the same time, the heater 142 is moved up and down by controlling the driving of the heater driving unit 143 based on the data obtained by the heat transfer analysis so that the temperature of the silicon melt 116 is always uniform.

  In applying a magnetic field, it is possible to set the magnetic field center position of the magnetic field application unit 140 first and not move the magnetic field center position, but the crucible 130 moves relatively upward as the amount of the silicon melt 116 decreases. Therefore, it is preferable to move the magnetic field center position of the magnetic field application unit 140 to the optimum position below the surface of the silicon melt 116 following the movement of the surface of the silicon melt 116.

  The above is the configuration of the silicon single crystal pulling apparatus 100 according to the embodiment of the present invention. As described above, the silicon single crystal pulling apparatus 100 according to the embodiment of the present invention performs heat transfer analysis of the quartz crucible 131 wall and the silicon melt 116 and adjusts the position of the heater 142 to adjust the silicon melting point. The temperature of the liquid 116 is made uniform, and non-uniformity of oxygen dissolution at the bottom of the quartz crucible 131 that occurs when a transverse magnetic field is applied to the silicon melt 116 is prevented. Accordingly, the in-plane oxygen concentration distribution can be made uniform while keeping the oxygen concentration of the silicon single crystal 115 high. The above effect is achieved by controlling the movement of the magnetic field driving unit 141, the heater driving unit 143, and the crucible rotation driving unit 150 in synchronization with each other by the control unit 160.

  Next, a method for pulling a silicon single crystal will be described with reference to FIG. FIG. 2 is an enlarged view of the main chamber 121 shown in FIG. In FIG. 2, the broken line of the magnetic field application unit 140 indicates a state in which the magnetic field application unit 140 is pulled down following the decrease in the surface of the silicon melt 116 in the second half of the crystal. Note that the same configuration as in FIG. 1 may not be described again.

  In the method for pulling up a silicon single crystal according to the embodiment of the present invention, as described above, there is a problem that if the rotation of the crucible is accelerated while applying a transverse magnetic field, deformation or polycrystallization occurs. It is slower than the law. The deformation or polycrystallization of the silicon single crystal 116 is caused by non-uniform oxygen concentration due to friction. When a transverse magnetic field is applied, the viscosity of the fluid increases, and when the crucible rotates faster, the fluid movement becomes unsteady. Oxygen that was distributed unevenly in the fluid is generated by being taken into the crystal. Therefore, in this embodiment, since the rotation of the crucible is slowed, it is considered that the influence of rotation (nonuniformity due to friction) is relatively small. Therefore, by making the temperature of the silicon melt 116 uniform, the in-plane oxygen concentration distribution can be made uniform. Therefore, the heater 142 is moved up and down in accordance with the conditions calculated to make the temperature of the silicon melt 116 uniform and the stage of growing the silicon single crystal 116.

  The silicon single crystal pulling method according to the embodiment of the present invention will be described. First, silicon filled in the quartz crucible is melted to obtain a silicon melt. Next, the silicon single crystal 115 is pulled up while applying a transverse magnetic field to the silicon melt by the magnetic field applying unit 140. At this time, the crucible 130 is rotated and moved up and down by the crucible rotation driving unit 150. In synchronization with the rotation and elevation of the crucible 130, the magnetic field driving unit 141 moves the magnetic field application unit 140 up and down so that the magnetic field center position of the magnetic field application unit 140 is always located at a predetermined position from the surface of the silicon melt 116. Here, the predetermined position of the magnetic field center position of the magnetic field application unit 140 is that the depth of the silicon melt 116 is B, and the vertical position of the lower surface (lowest surface) of the silicon melt 116 in the quartz crucible 131 is L. When the L is a reference and the seed crystal side is +, the magnetic field center position is + 1 / 2B + L to + 1 / 3B + L. Thereby, the magnetic field center position always follows the center of the depth B of the silicon melt 116 or the position 1/3 of the depth B of the silicon melt 116. Further, in synchronization with the rotation and elevation of the crucible 130 and the elevation of the magnetic field application unit 140, the silicon melt is obtained based on the data obtained by performing the heat transfer analysis in advance so as to keep the temperature of the silicon melt 116 uniform. The position of the heater 142 that heats the liquid 116 is raised and lowered. Here, the adjustment of the position of the heater 142 based on the data obtained by the heat transfer analysis is based on the position where the upper end of the heater 142 and the upper end of the graphite crucible 131 coincide with each other. When the upper end is positioned on the upper side, the upper side of the graphite crucible 131 is made to follow so that it is always +20 mm or more and +100 mm or less. More preferably, the position of the heater 142 is made to follow so that the upper end of the graphite crucible 131 is always +45 mm. This is because if the upper end of the graphite crucible 131 is less than +20 mm, the effect is difficult to obtain, and if it exceeds +100 mm, the silicon single crystal may freeze. Thus, in the embodiment of the present invention, the position of the crucible 130, the position of the magnetic field application unit 140, and the position of the heater 142 are varied in synchronization.

  The silicon single crystal pulling method according to the embodiment of the present invention is summarized as follows. In synchronism with the raising and lowering of the quartz crucible 131 when the silicon single crystal 116 is pulled, the magnetic field center position of the magnetic field applying unit 140 is the silicon melt 116. The magnetic field application unit 140 is moved up and down so that it is always located at a predetermined position from the surface of the magnetic field. Further, a heater for heating the silicon melt 116 based on data obtained by performing heat transfer analysis so as to keep the temperature of the silicon melt 116 in synchronization with the raising and lowering of the quartz crucible 131 and the magnetic field applying unit 140. Is a method of moving up and down.

  As described above, the silicon single crystal pulling method according to the embodiment of the present invention performs the heat transfer analysis of the quartz crucible 131 wall and the silicon melt 116 and adjusts the position of the heater 142 to adjust the silicon melt. The temperature of 116 is made uniform to prevent non-uniformity of oxygen dissolution at the bottom of the quartz crucible 131 that occurs when a transverse magnetic field is applied to the silicon melt 116. Accordingly, the in-plane oxygen concentration distribution can be made uniform while maintaining a high oxygen concentration in the silicon single crystal 115 to be grown. The above effect is achieved by controlling the movement of the magnetic field driving unit 141, the heater driving unit 143, and the crucible rotation driving unit 150 in synchronization with each other by the control unit 160.

  More preferably, the specific flow rate of the inert gas is reduced. As is well known, oxygen constantly evaporates from the surface of the silicon melt 116, and a low oxygen concentration region is formed near the surface of the silicon melt 116. This low oxygen concentration region is also taken into the flow of the silicon melt 116 with a very small effect, and is one factor that deteriorates the in-plane distribution of the oxygen concentration. Therefore, a condition where the specific flow rate is reduced and evaporation is suppressed is more desirable. When the specific flow rate is lowered, high oxygenation can be achieved at the same time.

  Next, examples and comparative examples according to the embodiment of the present invention will be described.

  In this example, in the method of pulling up the silicon single crystal by the HMCZ method, the quartz crucible 131 was 22 inches (558.8 mm) and the charge amount was 100 kg in order to grow the silicon single crystal 115 with a diameter of 200 mm. It is an example. In this example, the silicon single crystal 115 was grown with a diameter of 200 mm, but the silicon single crystal pulling method according to the embodiment of the present invention is not limited to this. For example, the diameter of the silicon single crystal 115 is 300 mm or more. It can also be cultivated as a large diameter.

  In this embodiment, the heat transfer analysis is performed by FEMAG (total heat transfer analysis software) at the position of the magnetic field center always at a position of −100 mm from the surface of the silicon melt, and the quartz crucible 131 is placed on the basis of the heat transfer analysis result. The position of the heater 142 was adjusted so that the temperature of the heater was uniform. Here, the adjustment of the position of the heater 142 based on the heat transfer analysis is based on the position where the upper end of the heater 142 and the upper end of the graphite crucible 131 coincide with each other. When the case is in the + side, the upper end of the graphite crucible 131 is made to follow +45 mm.

The results of measuring the in-plane oxygen concentration distribution and the oxygen concentration at the crystal length (1979 ASTM) of the silicon single crystal grown according to this example are shown in 201 of FIG. 3, FIG. 4A, and FIG. FIG. 3 is a graph showing the oxygen concentration (E18 atoms / cm ³ ) at the crystal length (mmL), where the horizontal axis shows the crystal length (mmL) and the vertical axis shows the oxygen concentration (E18 atoms / cm ³ ). FIG. 4A is a diagram showing the in-plane oxygen concentration distribution of the silicon single crystal, where the horizontal axis indicates the oxygen concentration (E18 atoms / cm ³ ), and the vertical axis indicates the distance (mm) on the test piece. Here, the distance on the test piece corresponds to the distance in the growth direction of the grown silicon single crystal. Moreover, a test piece means what cut | disconnected a 70-75-cm part of crystal straight cylinders longitudinally, and cut out from the center part of a crystal axis as thickness 0.775mm and width 10mm. FIG. 5 is a diagram showing the in-plane oxygen concentration in the crystal length (mmL), where the horizontal axis indicates the crystal length (mmL) and the vertical axis indicates Δ [Oi] (%). Here, Δ [Oi] (%) is the in-plane oxygen concentration ((MAX−MIN) / MIN × 100).

As can be seen from FIG. 3, in this example, the oxygen concentration of the silicon single crystal is between 1.2 (E18 atoms / cm ³ ) and 1.4 (E18 atoms / cm ³ ), which is the target value of the oxygen concentration. The oxygen concentration is stable with a small fluctuation range.

  As can be understood from FIG. 4A, in this embodiment, the in-plane oxygen concentration distribution is substantially uniform.

Further, as can be seen from FIG. 5, in this embodiment, the fluctuation range of the in-plane oxygen concentration is small and the oxygen concentration is stable.
[Comparative Example 1]
In order to verify the effects of the above-described embodiment, Comparative Examples 1 and 2 described below were measured.

  In Comparative Example 1 and Comparative Example 2, in the method of pulling up the silicon single crystal by the HMCZ method, the quartz crucible 131 is 22 inches (558.8 mm) in order to grow the silicon single crystal 115 with a diameter of 200 mm, and the charge amount Is 100 kg.

  Comparative Example 1 is an example in which a silicon single crystal is grown by adjusting the position of the magnetic field at a position of ± 0 from the surface of the silicon melt and adjusting the heater position.

The result of measuring the oxygen concentration at the crystal length in the grown silicon single crystal is shown at 202 in FIG. As understood from FIG. 3, the oxygen concentration of the silicon single crystal is 1.2 (E18 atoms / cm ³ ) to 1.4, which is the target value of the oxygen concentration from the initial stage of growth of the silicon single crystal to the middle stage of growth. Although it is between (E18 atoms / cm ³ ), the oxygen concentration becomes lower in the latter half of the crystal and deviates from the target value, and the fluctuation range is large and the oxygen concentration is unstable.

  Next, as Comparative Example 2, an example in which the magnetic field center position is raised and lowered while the heater is not adjusted will be described.

  In Comparative Example 2, a silicon single crystal was grown at a magnetic field center position that was always −100 mm from the surface of the silicon melt.

  The results of measuring the oxygen concentration distribution in the plane of the grown silicon single crystal and the oxygen concentration at the crystal length are shown in 203 of FIG. 3, FIG. 4B, and FIG. Since the units of the vertical axis and the horizontal axis in FIGS. 3, 4B and 5 are the same as those in the above-described embodiment, description thereof will be omitted.

As understood from FIG. 3, in Comparative Example 2, the oxygen concentration of the silicon single crystal is between 1.2 (E18 atoms / cm ³ ) and 1.4 (E18 atoms / cm ³ ), which is the target value of the oxygen concentration. Although it is improved compared with the comparative example 1, it is grasped | ascertained that the fluctuation range is larger than an Example and oxygen concentration is unstable.

  Further, as can be seen from FIG. 4B, in the comparative example 2, the in-plane oxygen concentration distribution is not uniform.

  Further, as understood from FIG. 5, in Comparative Example 2, the fluctuation range of the in-plane oxygen concentration is larger than that of the example, and the oxygen concentration is unstable.

  As described above, when Example is compared with Comparative Example 1 and Comparative Example 2, the present example, in which the magnetic field center position is lowered and the temperature distribution of the surface of the silicon melt and the quartz crucible wall is adjusted, is a silicon single crystal. It is understood that the in-plane oxygen concentration distribution is made uniform while maintaining a high oxygen concentration. On the other hand, in the case where the magnetic field center position of Comparative Example 1 is not lowered and the temperature distribution is not adjusted, the oxygen concentration in the crystal length becomes a low oxygen concentration in the latter half of the crystal, the fluctuation range is large, and the oxygen concentration is unstable. I understand that. Therefore, a uniform high oxygen concentration silicon single crystal cannot be obtained. Further, in the case where the magnetic field center position of Comparative Example 2 is lowered and the temperature distribution is not adjusted, it can be seen that the in-plane oxygen concentration distribution is non-uniform although it is improved over Comparative Example 1. Therefore, a silicon single crystal having a uniform in-plane oxygen concentration distribution cannot be obtained.

  Note that the silicon single crystal pulling apparatus 100 according to the embodiment of the present invention is not limited to the above-described example, and can be modified. For example, as a first modification, the shape of the heater of the silicon single crystal pulling apparatus 100 may be changed. As an example, the shape is similar to the shape of the crucible. However, the shape of the heater is not particularly limited as long as the temperature of the silicon melt and the quartz crucible wall can be made uniform.

  As a second modification, a bottom heater may be provided below the crucible of the silicon single crystal pulling apparatus 100. The bottom heater can be used to keep the temperature below the quartz crucible uniform. Furthermore, the oxygen concentration of the silicon single crystal can be further increased by providing the bottom heater at the lower part of the crucible. Moreover, you may make a bottom heater track according to the crucible which goes up and down with the reduction | decrease of a silicon melt.

It is a schematic sectional drawing which shows the pulling apparatus of the silicon single crystal which concerns on embodiment of this invention. It is a general | schematic expanded sectional view which shows the main chamber of the pulling apparatus of the silicon single crystal shown in FIG. 1 which concerns on embodiment of this invention. It is a figure which shows the oxygen concentration of the crystal | crystallization full length of the silicon single crystal which concerns on embodiment of this invention. (A) is a figure which shows oxygen concentration distribution in the surface of the silicon single crystal which concerns on the Example of this invention, (b) is a figure which shows oxygen concentration distribution in the surface of the silicon single crystal which concerns on a comparative example. is there. It is a figure which shows the oxygen concentration in the surface of the silicon single crystal which concerns on embodiment of this invention.

Explanation of symbols

  100: Silicon single crystal pulling device, 110: Winding mechanism, 111: Winding unit, 112: Wire rotation driving unit, 113: Wire, 114: Seed crystal, 115: Silicon single crystal, 116: Silicon melt, 117: Table: 118: Rotating shaft, 120: Furnace body, 121: Main chamber, 122: Pull chamber, 130: Crucible, 131: Quartz crucible, 132: Graphite crucible, 140: Magnetic field applying unit, 141: Magnetic field driving unit, 142: Heater 143: heater driving unit, 144: radiation shield, 145: first heat retaining member, 146: second heat retaining member, 147: third heat retaining member, 150: crucible rotation driving unit, 160: control unit

Claims (2)

A crucible composed of a quartz crucible and a graphite crucible that melts silicon into a silicon melt; and
A crucible rotation drive unit that moves up and down while rotating the crucible;
A heater that is a heat generation source for melting the silicon;
A heater drive for raising and lowering the heater;
A magnetic field application unit for applying a magnetic field to the silicon melt;
A magnetic field drive unit for moving the magnetic field application unit up and down;
A controller that is connected to the crucible rotation driving unit, the heater driving unit, and the magnetic field driving unit, and controls the driving of the crucible rotation driving unit, the heater driving unit, and the magnetic field driving unit;
The control unit synchronizes with the raising and lowering of the crucible by the crucible rotation driving unit, and sets the depth of the silicon melt to B, and the vertical direction of the lower surface (lowest surface) of the silicon melt in the quartz crucible When the position is L and the seed crystal side is + with reference to L, the drive of the magnetic field drive unit is controlled so that the magnetic field center position of the magnetic field application unit is located in + 1 / 2B + L to + 1 / 3B + L. raises and lowers the magnetic field application unit, at the same time, the upper ends and the graphite crucible of the silicon melt by controlling the drive of the pre-Symbol heater driving unit so that the temperature is always uniform raising and lowering the heater the heater The upper end of the graphite crucible becomes +20 mm or more and +100 mm or less when the upper end of the graphite crucible is located on the upper side of the upper end of the heater with respect to the matched position. The silicon single crystal pulling apparatus according to claim Rukoto is urchin follow. In the silicon single crystal pulling method of pulling up the silicon single crystal from the silicon melt in the quartz crucible while applying a transverse magnetic field by the magnetic field applying unit,
As the silicon single crystal is pulled up, the quartz crucible is raised and lowered while rotating, and the depth of the silicon melt is set to B, and the vertical position of the lower surface (lowest surface) of the silicon melt in the quartz crucible is set. When L is used as a reference and the seed crystal side is +, the magnetic field application unit is moved up and down so that the magnetic field center position of the magnetic field application unit is located in + 1 / 2B + L to + 1 / 3B + L.
In synchronism with the raising and lowering of the quartz crucible and the magnetic field application unit, the heater for heating the silicon melt in the quartz crucible is raised and lowered so as to keep the temperature of the silicon melt uniform, and the upper end of the heater and the graphite The upper end of the graphite crucible is +20 mm or more and +100 mm or less when the upper end of the graphite crucible is located on the upper side of the upper end of the heater with respect to the position where the upper ends of the crucibles are matched. A method for pulling a silicon single crystal, which is characterized in that the following is performed .

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