JP6425332B2 - Single crystal silicon pulling apparatus and single crystal silicon pulling method - Google Patents

Description

  The present invention relates to a single crystal silicon pulling apparatus and a single crystal silicon pulling method, and more particularly to a single crystal silicon pulling temperature control.

Single crystal silicon used for semiconductor substrates and the like is generally manufactured by the Czochralski method (hereinafter referred to as the CZ method).
In the CZ method, polycrystalline silicon (raw material silicon) is placed in a quartz crucible placed in a high pressure and pressure tight chamber, and the polycrystalline silicon is heated by heating a heater placed so as to surround the quartz crucible, It melts to form a silicon melt. Then, a seed (seed crystal) is attached to a seed chuck disposed above the quartz crucible, and the seed is immersed in the silicon melt in the quartz crucible, and the seed is pulled up while rotating the seed and the quartz crucible. Silicon is grown (see, for example, Patent Document 1). In the pulling of single crystal silicon, the heater is controlled along a temperature control line in which the length (pulling length) of the single crystal silicon to be pulled up corresponds to the temperature of the quartz crucible.

  In the production of single crystal silicon in such a CZ method, it is important to maintain a dislocation-free state during pulling up of single crystal silicon. However, for example, the temperature of the wall surface of the quartz crucible rises to melt a large amount of raw material silicon, and the natural convection of the silicon melt intensifies, so that the melting of the quartz crucible proceeds and small particles of insoluble matter (cristobalite) By adhering to the growth interface, the single crystal silicon during pulling up may be dislocated. If the pulling single crystal silicon is dislocated, the pulling is stopped at that point, and the single crystal silicon already pulled is taken out.

  If such dislocation formation occurs at a position significantly shorter than the planned pulling-up length of single crystal silicon, a large amount of silicon melt remains in the quartz crucible. It is very time-consuming to use the remaining silicon melt by cooling, solidifying and recovering it as silicon raw material again, and there is also the possibility of contamination by impurities in the process of recovery. For this reason, using the silicon melt remaining in the quartz crucible, pulling up another single crystal silicon shorter than the planned pulling up length is performed.

JP 2001-278696 A

  However, when pulling up another single crystal silicon from the silicon melt remaining in the quartz crucible due to the dislocation of the single crystal silicon, the temperature of the quartz crucible along the temperature control line corresponding to the initially planned pulling up length. When control is performed, for example, there is a problem that the shape of the shoulder portion of single crystal silicon changes. For example, the shape of the shoulder portion of single crystal silicon pulled up again may have a so-called shoulder shape with so-called 撫 in which the inclination is steep compared with the shape of the shoulder portion of single crystal silicon pulled up first .

  Such change in the shape of the shoulder portion is due to the fact that the amount (remaining amount) of silicon melt at the time of redrawing is smaller than the amount of silicon melt in the quartz crucible at the time of the first pulling. That is, when the amount of silicon melt in the quartz crucible decreases, the height position of the quartz crucible rises in order to maintain the liquid level of the silicon melt at a predetermined position. One of the causes is that the temperature condition of single crystal silicon at the time of redrawing is changed.

  The present invention has been made in view of the above-described circumstances, and when pulling up another single crystal silicon from the silicon melt remaining in the quartz crucible after the single crystal silicon pulled first has dislocations, A single crystal silicon pull-up device capable of preventing a large change in the shape of the shoulder portion of the single crystal silicon as compared with the shape of the shoulder portion of the single crystal silicon pulled first, and a single crystal silicon pull-up device It is an object of the present invention to provide a crystalline silicon pulling method.

In order to solve the above-described problems, a single crystal silicon pulling up apparatus according to the present invention comprises: a quartz crucible; crucible driving means for rotating the quartz crucible around an axis and changing the height position of the quartz crucible; A single crystal silicon pulling up apparatus comprising at least a heater for melting a silicon raw material accommodated in a quartz crucible to form a silicon melt, and a control unit for controlling the crucible driving means and the heater. The heater is formed along a first shoulder portion temperature control line indicating a relationship between a temperature of the silicon melt and a length of the shoulder portion of the single crystal silicon when forming the shoulder portion of the single crystal silicon. And the control unit is configured to control the remaining portion of the silicon melt remaining in the quartz crucible when the single crystal silicon is dislocated at a position shorter than a predetermined pulling length. Are configured to generate a second shoulder portion temperature control line in accordance with said second shoulder portion temperature control lines than said first shoulder portion temperature control line, a short time the silicon melt Forming a curve that lowers the temperature of the

According to the single-crystal silicon pull-up apparatus of the present invention, when pulling up another single-crystal silicon from the silicon melt remaining in the quartz crucible after the single-crystal silicon pulled first has a dislocation, the quartz crucible is used. The control unit generates a second shoulder portion temperature control line optimized in accordance with the remaining amount of silicon melt remaining. As a result, the shape of the shoulder portion of single crystal silicon pulled up in a state where the amount of silicon melt decreases decreases significantly compared to the shape of the shoulder portion of single crystal silicon pulled up first. It can be prevented.
The temperature of the silicon melt is substantially the same as the temperature of the quartz crucible, and the temperature of the silicon melt can be the temperature of the quartz crucible.
In addition, a single-crystal silicon having a shoulder similar to the shape of the shoulder of single-crystal silicon pulled first by setting the second shoulder temperature control line to a curve that lowers the temperature of the quartz crucible in a short time Can be pulled from the silicon melt remaining in the quartz crucible.

In the present invention, the control unit may include a crystal weight of single crystal silicon up to a position where dislocation occurs, a pull-up length of single crystal silicon up to a location where dislocation occurs, and a height of the quartz crucible at a position where dislocation occurs. The second shoulder portion temperature control line is generated based on at least one or more parameters of the position.
These second shoulder temperature control lines are generated by generating a second shoulder temperature control line reflecting the parameters of the first pull-up single crystal silicon and the parameters related to the position of the quartz crucible. The single crystal silicon having a shoulder similar to the shape of the shoulder of the single crystal silicon initially pulled can be pulled from the silicon melt remaining in the quartz crucible.

In the present invention, the control unit performs the second shoulder portion temperature based on the temperature of the silicon melt at the time of forming the neck portion when pulling up single crystal silicon from the silicon melt remaining in the quartz crucible again. Generating a control line.
The second shoulder temperature control line is generated by reflecting a parameter related to the temperature of the quartz crucible at the time of neck formation when pulling up single crystal silicon again to generate a second shoulder temperature control line. The single crystal silicon having a shoulder similar to the shape of the shoulder of the single crystal silicon pulled first can be pulled from the silicon melt remaining in the quartz crucible.

The single crystal silicon pulling method of the present invention is a single crystal silicon pulling method using the single crystal silicon pulling apparatus according to each of the above items, wherein a predetermined amount of silicon raw material is introduced into the quartz crucible; Heating the heater along the first shoulder portion temperature control line to form a shoulder portion of single crystal silicon from a silicon melt obtained by melting the silicon raw material; Stopping the pulling of the single crystal silicon when dislocation occurs at a position shorter than the upper length, and forming the second shoulder portion temperature control line, and along the second shoulder portion temperature control line heating said heater Te, from the remaining silicon melt to the quartz crucible, comprises the steps of forming a shoulder portion of another single crystal silicon, in this order, the second shoulder Part Temperature control lines than said first shoulder portion temperature control line, and wherein the curvilinear to lower the temperature of the silicon melt in a short time.

  According to the single crystal silicon pulling method of the present invention, when pulling up another single crystal silicon from the silicon melt remaining in the quartz crucible after the single crystal silicon pulled first has a dislocation, the quartz crucible is used. The shoulder of the single crystal silicon pulled up in a state where the amount of silicon melt is reduced by the control unit generating a second shoulder portion temperature control line optimized according to the remaining amount of the remaining silicon melt The shape of the portion can be prevented from largely changing as compared with the shape of the shoulder portion of single crystal silicon pulled up first.

  According to the single crystal silicon pull-up apparatus and the single crystal silicon pull-up method of the present invention, another single crystal silicon is pulled from the silicon melt remaining in the quartz crucible after the single crystal silicon pulled first has dislocation. At the time of lifting, it is possible to prevent the shape of the shoulder portion of the single crystal silicon from being greatly changed as compared with the shape of the shoulder portion of the single crystal silicon pulled up first.

It is sectional drawing which shows the single-crystal silicon pulling-up apparatus of this invention. It is a flowchart which shows an example of the single crystal silicon pulling-up method of this invention. It is an explanatory view explaining the shape of single crystal silicon. It is a graph which shows the shoulder part temperature control line of single crystal silicon. It is a graph which shows the example of verification of the present invention. It is a graph which shows the example of verification of the present invention. It is a graph which shows the conventional verification example. It is a graph which shows the conventional verification example.

  The single crystal silicon pulling up apparatus and the single crystal silicon pulling up method of the present invention will be described below with reference to the drawings. Each embodiment shown below is concretely described in order to understand the meaning of the invention better, and does not limit the present invention unless otherwise specified. Further, in the drawings used in the following description, for the sake of easy understanding of the features of the present invention, the main parts may be enlarged for convenience, and the dimensional ratio of each component may be the same as the actual one. Not necessarily.

The configuration of the single crystal silicon pulling apparatus of the present invention will be described.
FIG. 1 is a schematic view showing an example of a single crystal silicon pulling apparatus. The single-crystal silicon manufacturing apparatus 1 includes a pressure-tight chamber 10, a quartz crucible 15, a seed chuck 17, a heater 19, a crucible support 21 and a seed chuck driving mechanism 30, and is in a reduced pressure state. In the chamber 10, the seed S attached to the seed chuck 17 is immersed in the silicon melt M stored in the quartz crucible 15, and pulled up while rotating to grow single crystal silicon T. .

  The chamber 10 includes a main chamber 11, a top chamber 12 connected to the upper side of the main chamber 11, and a pull chamber 13 connected to the upper side of the top chamber 12. The main chamber 11 is provided upright on the bottom 11A and the bottom 11A. The quartz crucible 15 is disposed at the central portion, and a vacuum pump (not shown) is connected to the exhaust hole 11D so that the pressure in the chamber 10 can be reduced or reduced. .

  Further, the spill tray 14 is disposed at the bottom 11A of the main chamber 11, and the silicon melt M is in direct contact with the bottom 11A when the quartz crucible 15 is broken and the silicon melt M flows out. It is possible to prevent the chamber from being broken.

  The pull chamber 13 is formed in a substantially cylindrical shape, has a space for containing the pulled single crystal silicon T, and is connected to the main chamber 11 by the top chamber 12. A shutter (not shown) for thermally isolating the pull chamber 13 from the main chamber 11 and the top chamber 12 is formed between the pull chamber 13 and the top chamber 12. Even when the silicon melt M is stored in the quartz crucible 15 by such a shutter, the single crystal silicon T in a state where only a part of the initially planned pulling up length is pulled from the pull chamber 13 is obtained. It has a removable structure.

  The quartz crucible 15 is capable of holding massive polycrystalline silicon (raw material silicon) which is a raw material of single crystal silicon T in the recess of the quartz crucible 15, and a silicon melt formed by heating and melting the polycrystalline silicon. M can be stored, and is stored in the graphite crucible 16. For example, by controlling the temperature of the quartz crucible 15, the temperature of the silicon melt M can be maintained at a desired temperature.

  The graphite crucible 16 is integrally formed by being held by a pedestal 21C disposed on the upper surface of the crucible support 21. The support 21A of the crucible support 21 is formed at the central portion of the bottom 11A of the main chamber 11. It is inserted into a through hole 11H formed through the bottom portion 11A and the spill tray 14 so that rotation and vertical movement relative to the main chamber 11 are possible.

Further, a cylindrical heater 19, a cylindrical heat retaining cylinder 22 outside the heater 19, and a radiation thermometer 40 outside the heat retaining cylinder 22 are disposed around the graphite crucible 16.
The heat retaining cylinder 22 includes an inner heat retaining cylinder 22A made of cylindrical graphite and an outer heat retaining cylinder 22B made of porous cylindrical porous graphite disposed outside the inner heat retaining cylinder 22A, and the inner diameter of the inner heat retaining cylinder 22A. A disc-shaped upper ring 22D is disposed on the disc-shaped lower ring 22C in which a hole of substantially the same inside diameter as the above is formed, and a hole of substantially the same inside diameter as the inside diameter of the inner heat retaining cylinder 22A is formed thereon It is done.

  The lower part of the heater 19 is fixed to the electrode joint 19A with a bolt 19B, and the electrode joint 19A is connected to the power supply device P1 via a graphite electrode 19C disposed in a through hole formed in the spill tray 14. The heater 19 controls the power supplied from the power supply device P1 so that, for example, the temperature of the silicon melt M is maintained at a predetermined temperature.

  The radiation thermometer 40 is for measuring the temperature of the heat insulating cylinder 22. In the present embodiment, the power of the heater 19 is adjusted based on the measurement data of the radiation thermometer 40 to control the temperature of the silicon melt M. The temperature measured by the radiation thermometer 40 is substantially the same as the temperature of the quartz crucible 15.

The electric power of the heater 19 is controlled so that the temperature measured by the radiation thermometer 40 becomes temperature data set in advance.
The temperature data consists of the growth amount of single crystal silicon T (the growth length from the liquid surface of silicon melt M) and the temperature inclination set according to the growth amount of single crystal silicon. In this embodiment, this growth amount is associated with the pulling up length of single crystal silicon T. Details of the temperature data will be described later.

A flow pipe 25 is attached to the upper end of the heat insulating cylinder 22 via an upper ring 22D and an adapter 23.
The flow tube 25 is a hollow cylinder in the shape of an inverted truncated cone whose upper end opening has a larger diameter than the lower end opening, and is made of graphite or SiC.
The seed chuck 17 has a proximal end connected to the wire W, and the wire W is connected to the seed chuck drive mechanism 30 so that the seed S can be rotated and lifted relative to the main chamber 11.

  The seed chuck driving mechanism 30 is provided at the upper part of the pull chamber 13 and can be rotated relative to the pull chamber 13 with the wire W as a rotational axis O, with the pulley 31 connected and wound around the base end side of the wire W And the seed chuck 17 is raised and lowered by winding the wire W by the pulley 31 so that the seed chuck 17 is pivoted around the wire W by the rotation of the rotary drive portion 32. It has become.

  Furthermore, the manufacturing apparatus 1 of single crystal silicon includes a control unit 50. The control unit 50 is configured to be able to control the rotation of the crucible support 21 and the rotation and elevation of the seed chuck drive mechanism 30, and the rotation direction and rotational speed of the crucible support 21 and the rotational drive of the seed chuck drive mechanism 30. It is possible to control the rotation direction and rotation speed of the seed chuck 17 by the unit 32 and the raising and lowering (raising) speed of the seed chuck 17 by the pulley 31.

  The control unit 50 includes, for example, a first inverter 51, a second inverter 52, a third inverter 53, a fourth inverter 55, and an operation unit 54. The first inverter 51, the second inverter The inverter 52, the third inverter 53, and the fourth inverter 55 are configured to send out a drive signal based on an instruction signal from the calculation unit 54.

  The control unit 50 changes, for example, the frequency of the first inverter 51 to control the drive mechanism M1 that rotates and moves the crucible support 21 vertically, whereby the rotation direction, the number of rotations, and the number of rotations of the quartz crucible 15 It is possible to control the vertical position (height position). The rotation speed of the crucible support 21 can be adjusted, for example, from 1.0 rpm to 30 rpm. In addition, the height position of the crucible support 21 is such that the liquid level position of the silicon melt M with respect to the main chamber 11 is always constant corresponding to the decrease of the silicon melt M accompanying the growth of the single crystal silicon T. It is controlled.

In addition, the control unit 50 changes the frequency of the second inverter 52 to control the rotation direction and the number of rotations of the motor M2 that rotates the rotation drive unit 32 of the seed chuck drive mechanism 30, thereby rotating the seed chuck 17. The rotation direction (right rotation, left rotation) and rotation speed around the axis O can be adjusted, and the rotation speed of the seed chuck 17 can be adjusted from 0.5 rpm to 15 rpm.
The second inverter 52 and the motor M2 constitute a seed rotation control means.

Further, the control unit 50 changes the frequency of the third inverter 53 to control the rotational direction and the number of rotations of the motor M3 that rotates the pulley 31 on which the wire W is wound. The pulling speed can be adjusted, and the pulling speed of the seed chuck 17 can be adjusted from 0.01 rpm to 10 rpm.
The third inverter 53 and the motor M3 constitute a seed pulling speed control means.

  Further, the control unit 50 controls the voltage and the current output from the power supply device P1 via the fourth inverter 55. As a result, the power of the heater 19 can be controlled to set the temperature of the silicon melt M to a predetermined temperature. The fourth inverter 55 is controlled based on the temperature of the heat insulating cylinder 22 detected by the radiation thermometer 40. The heater 19 performs temperature control in accordance with a temperature control curve input to the control unit 50. Such temperature control of the heater 19 will be described in detail later.

In addition to the control based on the temperature of the heat insulating cylinder 22 detected by the radiation thermometer 40, the fourth inverter 55 directly measures the temperature of the quartz crucible 15 using, for example, a thermocouple. It may be
In the present invention, the temperature of the silicon melt M is substantially the same as the temperature of the quartz crucible 15. Therefore, the fourth inverter 55 may be configured to measure the temperature of the silicon melt M by the radiation thermometer 40.

Next, the operation of the single-crystal silicon manufacturing apparatus 1 having the above-described configuration and the method for manufacturing single-crystal silicon of the present invention will be described.
FIG. 2 is a flow chart showing the method of manufacturing single crystal silicon of the present invention stepwise. In the method of manufacturing a silicon single crystal of the present invention, for example, a manufacturing apparatus 1 of single crystal silicon shown in FIG. 1 is used.
First, bulk polycrystalline silicon (raw material silicon), which is a raw material, is filled in the quartz crucible 15 (raw material filling step S1). Then, the quartz crucible 15 is heated by the heater 19 to form a silicon melt M obtained by melting polycrystalline silicon, and the silicon melt M in the vicinity of the portion in which the seed S is immersed is brought into a supercooled state Raw material melting step S2).

  Then, the seed S is inserted into the seed chuck 17 and fixed. Next, the seed chuck driving mechanism 30 is driven to lower the seed chuck 17 to immerse the seed S in the silicon melt M, and the seed S is made to conform to the silicon melt M (seed immersion step S3).

  When the seed S is absorbed in the silicon melt M, the seed chuck 17 is raised while rotating. The seed S is for growing single crystal silicon from the silicon melt M, and when the seed S is in contact with the silicon melt M, the single crystal silicon T having the same atomic arrangement as the seed S is connected to the seed S To grow (first crystal growth step S4).

  As shown in FIG. 3, the silicon single crystal T has a neck portion Tn extending from the seed S with a small diameter, a shoulder portion Ts connected to the neck portion Tn and the diameter expanded, and a predetermined diameter extending from the shoulder portion Ts. It consists of a straight body portion Tb. The end of the straight body Tb is formed to form a curved surface.

  The neck portion Tn has a shape in which the diameter is narrowed to cut off the handover of the crystal defect so that the crystal defect present in the seed S is not transferred to the region after the shoulder portion Ts.

  The shoulder portion Ts is a region whose diameter is increased to the diameter of the straight body portion Tb for cutting out a wafer. The straight body portion Tb is formed such that its diameter falls within a predetermined range. In the present invention, the shoulder portion Ts is an inversed hook-shaped portion between the upper position where the diameter of single crystal silicon starts to expand from the neck portion Tn and the lower position where the diameter is expanded to a target size. In the present invention, the length of the shoulder portion Ts is a length between the upper position and the lower position along the crystal growth axis of single crystal silicon.

  Pulling (crystal growth) of the silicon single crystal T refers to the rotation speed of the silicon single crystal T itself by the rotation of the seed chuck 17, the rotation speed of the quartz crucible 15 storing the silicon melt M by the rotation of the crucible support 21, the seed Growing a silicon single crystal T having desired properties by controlling the pulling rate by the rise of the chuck 17 and the heating temperature of the quartz crucible 15 by the heater 19 (approximately similar to the temperature of the silicon melt M). Can.

  Further, since the silicon melt M decreases with the crystal growth of the silicon single crystal T, the quartz crucible 15 storing the silicon melt M has its height position so that the silicon melt M corresponds to the amount of decrease. Will rise. By this, the liquid level position of the silicon melt M is always kept at a fixed position with respect to the chamber 10.

  The heating temperature of the quartz crucible 15 is controlled by the controller 50 by applying arbitrary power to the heater 19 via the fourth inverter 55. The optimum heating temperature of the quartz crucible 15 always fluctuates due to the change of the heat radiation characteristic according to the portion of the silicon single crystal pulled up and the change of the remaining amount of the silicon melt M. Therefore, the length of the silicon single crystal T along the pulling direction (hereinafter, may be referred to as pulling length) and the heating temperature of the heater 19 (hereinafter, may be referred to as the pulling temperature). The pull-up temperature is controlled to follow the temperature control line indicating the relationship. Such temperature control lines are generally indicated by curves.

  In the first crystal growth step S4, after forming the neck portion Tn, the silicon single crystal T is expanded in diameter to form the shoulder portion Ts (S4-1). FIG. 4 is a graph showing an example of the temperature lowering width of the pulling up temperature (first shoulder portion temperature control line Q1) when forming the shape of the shoulder portion (see the solid line in FIG. 4). In addition, the shoulder length of the horizontal axis in FIG. 4 means the pulling-up length along a pulling-up direction. Further, the temperature decrease width of the pull-up temperature indicates the value of the relative decrease width when the value at the start point of the shoulder portion Ts (the end point of the neck portion Tn) is 0.

  The first shoulder portion temperature control line Q1 forming the shape of the shoulder portion Ts has a relatively high temperature state because there are many heat dissipation portions due to the outer surface of the silicon single crystal T with the shape of the shoulder portion Ts facing upward. At the beginning of pulling up, it is linear to increase the temperature reduction width along with the diameter expansion of the silicon single crystal T. In the present invention, the control unit 50 controls the value of the power applied to the heater 19 along the first shoulder temperature control line Q1, and changes the pulling temperature to form the shoulder Ts of the silicon single crystal T. Do.

  When the shoulder portion Ts of the silicon single crystal T is formed, the straight body portion Tb is formed so as to maintain the diameter at the end portion of the shoulder portion Ts (S4-2). In forming such a straight barrel Tb, for example, the pulling temperature is controlled so as to gradually increase toward the end of the straight barrel Tb, and the silicon single crystal T is grown so as to fall within a predetermined diameter range.

  Then, when single crystal silicon T is grown without disarrangement over the entire length up to the originally planned pulling up length (planned pulling up length), the single crystal silicon pulled up from pull chamber 13 is taken out and the planned pulling up length Of single crystal silicon (S5).

  On the other hand, if the single crystal silicon is dislocated during the pulling up of the straight body portion Tb of the silicon single crystal T, the pulling is stopped at that point, and the single crystal silicon of the pulled portion is already pulled. The single crystal silicon with a pull-up length L1 shorter than the length is taken out (S6). The single crystal silicon of such a pulling up length L1 is also a single crystal silicon before the position having dislocation, and can be used for production of a silicon wafer or the like.

  On the other hand, in the quartz crucible 15, since the silicon melt M in an amount capable of pulling up the single crystal silicon of the pulling length initially planned in the raw material melting step S2 is stored, Even after taking out the crystals, a considerable amount of silicon melt M remains. From this remaining silicon melt M, a silicon single crystal having a pull-up length shorter than the originally planned pull-up length is further pulled up.

  The control unit 50 forms a second shoulder portion temperature control line Q2 corresponding to the amount of the remaining silicon melt M (S7). As indicated by a dotted line in the graph of FIG. 4, the second shoulder portion temperature control line Q2 has a larger amount of decrease in the pulling temperature with respect to the shoulder length than the first shoulder portion temperature control line Q1, ie, It is shown as linear which lowers the temperature of the quartz crucible in a short time.

The second shoulder portion temperature control line Q2 is formed based on at least one or more parameters. Such parameters include the crystal weight of single crystal silicon up to the position of dislocation, the pull-up length of single crystal silicon to the position of dislocation, and the height position of the quartz crucible at the position of dislocation.
The operator inputs one or more of these parameters to the control unit 50, and the control unit 50 generates a second shoulder portion temperature control line Q2 based on the input parameters.

At the time of re-lifting, the weight temperature conversion ratio calculated by the following formula is multiplied by the shoulder temperature decrease curve.
The shoulder cut weight temperature conversion coefficient was preset as a parameter, and the cut weight was actually cut.
The weight of the crystal is measured and input to the touch panel.
Weight temperature conversion ratio [%] = cut weight [kg] × shoulder cut weight temperature conversion coefficient [% / kg] + 100 [%]

  Using the second shoulder portion temperature control line Q2 thus obtained, another single crystal silicon is pulled up from the silicon melt M remaining in the quartz crucible 15 (second crystal growth step S8). First, after forming the neck portion Tn, the diameter is expanded to form the shoulder portion Ts (S8-1). At this time, the control unit 50 controls the value of the power applied to the heater 19 along the second shoulder portion temperature control line Q2, and changes the pulling temperature to form the shoulder portion Ts of the silicon single crystal T.

  Thus, according to the decrease of the silicon melt M, the crystal weight of single crystal silicon up to the position of dislocation, the pulling up length of single crystal silicon to the position of dislocation, and the position of dislocation By forming the shoulder portion Ts by the second shoulder portion temperature control line Q2 reflecting parameters such as the height position of the quartz crucible, the shape of the shoulder portion in the first single crystal silicon, for example, the external shape of the shoulder is almost Shoulders Ts of the same shape can be formed.

  The second shoulder portion temperature control line Q2 can also be generated reflecting the change in the pulling temperature when forming the neck portion Tn after the second crystal growth step S7 is started. In this case, the second shoulder portion temperature control line Q2 is generated after the second crystal growth step S7 is started.

  After the shoulder portion Ts of the silicon single crystal T is formed in the second crystal growth step S7, the straight body portion Tb is formed so as to maintain the diameter at the end portion of the shoulder portion Ts (S8-2). In forming such a straight barrel portion Tb, for example, the pulling temperature is controlled so as to gradually increase toward the end of the straight barrel portion Tb, and the silicon single crystal T with a pulling length L2 falls within a predetermined diameter range. Nurture

According to the above steps, when single crystal silicon is dislocated during the pulling, two single crystal silicons of single crystal silicon of pulling length L1 and single crystal silicon of pulling length L2 can be obtained. (S9).
The two single crystal silicons have almost the same shape of their shoulders and are surely expanded to the target diameter.

  Conventionally, when pulling up another single crystal silicon from the silicon melt M remaining after dislocation formation, the pulling temperature control at the time of forming the shoulder portion is the same as at the time of pulling up the first single crystal silicon, Although the shape of the shoulder may have largely changed from the original single crystal silicon or may not extend to the desired diameter, the second shoulder formed according to the remaining amount of silicon melt as in the present invention By using the temperature control line Q2, the single crystal silicon pulled up at the first time has almost the same shape as the shoulder portion, and the single crystal silicon which is surely expanded to the target diameter remains silicon after dislocation. It can be pulled up from the melt M.

  Moreover, although each shoulder part temperature control line mentioned above is a curve (temperature control curve), it may be the composition which connected a plurality of straight lines, and it is not limited to a curve. The linear shape of the illustrated temperature control line is an example, and is not limited to such a linear shape, and any linear temperature control line can be used.

  The second shoulder portion temperature control line Q2 is a shoulder portion temperature control line generated each time according to the remaining amount of silicon melt M when single crystal silicon is dislocated, and is twice or more. The second shoulder portion temperature control line can be generated each time the dislocation is generated.

  A verification example of the present invention is shown below. In the verification, a manufacturing apparatus 1 of single crystal silicon having a configuration shown in FIG. 1 was used.

  As an example of the present invention, when the first single crystal silicon is dislocated at 1270 mm with respect to the planned pulling length of 1800 mm, and the second single crystal is pulled from the remaining silicon melt, the first single crystal silicon is A shoulder was formed using a second shoulder temperature control line generated reflecting the crystal weight. FIG. 5 is a graph showing an example of the temperature reduction width of the pulling up temperature when forming the shape of the shoulder portion. The shoulder length of the horizontal axis in FIG. 5 means the pulling up length along the pulling up direction. Further, the temperature decrease width of the pull-up temperature indicates the value of the relative decrease width when the value at the start point of the shoulder portion Ts (the end point of the neck portion Tn) is 0. A first shoulder temperature control line Q1 (first single crystal silicon pulling up) is shown by a solid line, and a second shoulder temperature control line Q2 (second single crystal silicon pulling up) is shown by a dotted line.

  FIG. 6 is a graph showing the cross-sectional shapes of the shoulder Ts of the first and second silicon single crystals T when the shoulders are formed based on the shoulder temperature control lines Q1 and Q2 shown in FIG. 5, respectively. . The shoulder portion of the first monocrystalline silicon is shown by a solid line, and the shoulder portion of the second monocrystalline silicon is shown by a dotted line. In the graph shown in FIG. 6, in the cross section of the shoulder portion Ts, the crystal central axis is taken as the horizontal axis coordinate 0, and the outline of the shoulder portion Ts on one side from the crystal central axis is shown.

  As a comparative example, when the first single crystal silicon is dislocated at 887 mm with respect to the planned pulling length of 1800 mm, and when the second single crystal silicon is pulled from the remaining silicon melt, the first single crystal silicon is The first shoulder portion temperature control line used for forming the shoulder portion was used as it is to form a second shoulder portion of single crystal silicon.

  FIG. 7 is a graph showing an example of the temperature reduction width of the pulling up temperature when forming the shape of the shoulder portion. The shoulder length on the horizontal axis in FIG. 7 means the pulling up length along the pulling up direction. Further, the temperature decrease width of the pull-up temperature indicates the value of the relative decrease width when the value at the start point of the shoulder portion Ts (the end point of the neck portion Tn) is 0. A first shoulder temperature control line Q1 (first single crystal silicon pulling up) is shown by a solid line, and a second shoulder temperature control line Q2 (second single crystal silicon pulling up) is shown by a dotted line. The second shoulder portion temperature control line Q2 has a linear shape in which half or more of the second shoulder portion temperature control line Q2 overlaps the first shoulder portion temperature control line Q1.

  FIG. 8 is a graph showing the external shape of the shoulder Ts of the first and second silicon single crystals T when the shoulders are formed based on the shoulder temperature control lines Q1 and Q2 shown in FIG. 7 respectively. . The shoulder portion of the first monocrystalline silicon is shown by a solid line, and the shoulder portion of the second monocrystalline silicon is shown by a dotted line. In the graph shown in FIG. 8, in the cross section of the shoulder portion Ts, the crystal center axis is taken as the horizontal axis coordinate 0, and the outline of the shoulder portion Ts on one side from the crystal center axis is shown.

  As apparent from FIG. 8, in the comparative example (conventional example), when forming the second single-crystal silicon shoulder portion, the first single-crystal silicon first shoulder portion temperature control line is used as it is. Since the shoulder portion was formed, the decrease in the silicon melt was not reflected, and the shoulder portion became steeper than the first single crystal silicon (the shoulder at the heel).

On the other hand, as is clear from FIG. 6, in the example of the present invention, when forming the shoulder portion of the second single crystal silicon, the second shoulder portion generated reflecting the crystal weight of the first single crystal silicon By forming the shoulder using temperature control lines, it is possible to form a shoulder having substantially the same slope as that of the first single crystal silicon.
From the above results, the effects of the present invention were confirmed.

M silicon melt S seed T single crystal silicon 1 single crystal silicon manufacturing apparatus 10 chamber 15 quartz crucible (crucible)
19 heater

Claims (4)

With a quartz crucible,
Crucible driving means for rotating the quartz crucible about an axis and changing the height position of the quartz crucible;
A heater for melting a silicon raw material accommodated in the quartz crucible to form a silicon melt;
A single crystal silicon pulling up apparatus comprising at least a control unit for controlling the crucible driving means and the heater, wherein
When forming the shoulder portion of the single crystal silicon, the heater is arranged along a first shoulder portion temperature control line showing a relationship between the temperature of the silicon melt and the length of the shoulder portion of the single crystal silicon. Controlled
The control unit is configured to generate a second shoulder portion temperature control line according to the remaining amount of silicon melt remaining in the quartz crucible when the single crystal silicon is dislocated at a position shorter than a predetermined pulling length. Is configured to generate ,
A single crystal silicon pull-up device characterized in that the second shoulder portion temperature control line forms a curve which lowers the temperature of the silicon melt in a short time than the first shoulder portion temperature control line .   The control unit includes the crystal weight of single crystal silicon up to the position where dislocation occurs, the pulling up length of single crystal silicon up to the location where dislocation occurs, and the height position of the quartz crucible at the position where dislocation occurs. The single crystal silicon pulling-up apparatus according to claim 1, wherein the second shoulder portion temperature control line is generated based on at least one or more parameters. The control unit generates the second shoulder portion temperature control line based on the temperature of the silicon melt at the time of forming the neck portion when pulling back single crystal silicon from the silicon melt remaining in the quartz crucible. The single crystal silicon pulling-up apparatus according to claim 1 , characterized in that: A single crystal silicon pulling method using the single crystal silicon pulling device according to any one of claims 1 to 3 ,
Introducing a predetermined amount of silicon raw material into the quartz crucible, heating the heater along the first shoulder temperature control line, and melting the silicon raw material from a molten silicon melt; forming and forming said when single crystal silicon is that dislocations in a shorter position than expected pulling length set in advance, stops the pulling of the single crystal silicon, said second shoulder portion temperature control line And heating the heater along the second shoulder temperature control line to form another single crystal silicon shoulder from the silicon melt remaining in the quartz crucible. Yes,
A method of pulling a single crystal silicon according to claim 1, wherein said second shoulder portion temperature control line forms a curve which lowers the temperature of said silicon melt in a short time than said first shoulder portion temperature control line .

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