Single crystal pulling apparatus and method for manufacturing single crystal

Abstract

To keep a pulling speed constant for making the diameter of a single crystal become a target value when pulling the single crystal from a silicon melt by the Czochralski method and control the heating temperature of the silicon melt to suppress a variation in the diameter target value of the single crystal.SOLUTION: A single crystal pulling apparatus includes: a heater 4 for heating a silicon melt M; a heater control part 4a for supplying electric power to the heater; a cylindrical radiation shield 7 arranged above the silicon melt formed in the crucible and surrounding the periphery of a pulled single crystal; a diameter measurement device 16 for measuring the diameter of the pulled single crystal; a radiation thermometer 17 for measuring temperature on the side of the inner peripheral surface of the radiation shield; and a controller 11 for controlling electric power supplied to the heater by the heater control part. The controller controls the electric power supplied to the heater by the heater control part on the basis of the diameter of the single crystal measured by the diameter measurement device and the temperature on the side of the inner peripheral surface of the radiation shield measured by the radiation thermometer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a single crystal pulling apparatus and a method for manufacturing a single crystal, which perform pulling of a single crystal using the Czochralski method.

Background Art

[0002] For the growth of a silicon single crystal by the Czochralski method (CZ method), a quartz crucible 51 installed in a chamber 50 as shown in FIG. 6 is filled with polysilicon as a raw material, and the polysilicon is heated and melted by a heater 52 provided around the quartz crucible 51 to obtain a silicon melt M. Then, a seed crystal (seed) P attached to a seed chuck is immersed in the silicon melt, and the seed chuck is pulled up while rotating the seed chuck and the quartz crucible 51 in the same direction or in opposite directions.

[0003] Generally, prior to the start of pulling, after the temperature of the silicon melt M has stabilized, necking is performed by bringing the seed crystal P into contact with the silicon melt M to dissolve the tip portion of the seed crystal P. A neck portion P1 is formed by this necking.

[0004] Also, as a process after the start of pulling, after the completion of necking, a step of forming a shoulder portion C1 for expanding the crystal to the diameter of the straight body portion, a step of forming a straight body portion C2 for growing a single crystal to be a product, and a step of forming a tail portion (not shown) for gradually reducing the diameter of the single crystal after the straight body portion forming step are performed.

[0005] By the way, for a crystal generally called a defect-free crystal, when the pulling speed is v and the temperature gradient at the solid-liquid interface is G, v / G is controlled to be a certain value, and a crystal with a very low defect density is grown using this as an index. Also, the diameter of the single crystal to be pulled up is also controlled by the pulling speed v and the temperature gradient G. Specifically, the lower the melt temperature or the lower the pulling speed v, the larger the diameter of the single crystal. Conversely, the higher the melt temperature or the higher the pulling speed v, the smaller the diameter of the single crystal.

[0006] For example, in the single crystal pulling apparatus disclosed in Patent Document 1, the temperature of the silicon melt is measured by a two-color thermometer disposed at the top of the furnace, and the diameter of the single crystal is measured by a sensor through a window provided at the shoulder of the furnace, and the information is taken into a controller. The controller controls the pulling speed and the output of the heater to control the diameter of the single crystal by performing PID control using the diameter information of the single crystal and the measured melt temperature information.

Prior Art Document

Patent Document

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] When feedback control is performed on the heating temperature of the silicon melt by a heater and the pulling speed of the single crystal to be pulled up as in the single crystal pulling apparatus disclosed in Patent Document 1, accurate results can be obtained if the controlled result is immediate (has good responsiveness). For example, to control the pulling speed, it is only necessary to control the rotational speed of a reel that winds up a wire for lifting the single crystal. Generally, the rotational speed of the reel can be immediately reflected in the pulling speed.

[0009] However, when controlling the heating temperature of the silicon melt by a heater, a delay (time lag) occurs in the time until the change in the output of the heater is reflected in the temperature change of the solid-liquid interface, resulting in a lack of immediacy (low responsiveness) and a problem that the accuracy of controlling the diameter of the single crystal decreases.

[0010] In the configuration of the single crystal pulling apparatus disclosed in Patent Document 1, the liquid surface temperature of the silicon melt is directly measured by a two-color thermometer. However, in that case, there is a high risk that disturbances such as backlight components will be incorporated into the measurement results, and there is a risk that the accuracy of the measured temperature of the silicon melt will decrease. That is, conventionally, it has been difficult to accurately measure the temperature of the silicon melt, which has led to a decrease in the accuracy of the single crystal diameter control, resulting in a large variation in diameter or hunting.

[0011] In view of such circumstances, the inventor of the present application has conducted intensive research on accurately controlling the heating of the silicon melt and suppressing the variation in the diameter of the single crystal to be pulled up, and has arrived at the present invention.

[0012] An object of the present invention is to provide a single crystal pulling apparatus and a single crystal manufacturing method capable of suppressing variations in the diameter of a single crystal.

Means for Solving the Problems

[0013] The single crystal pulling apparatus according to the present invention, which has been made to solve the above problems, is a single crystal pulling apparatus for pulling up a single crystal from a silicon melt accommodated in a crucible in a chamber by the Czochralski method, and includes a heater for heating the silicon melt, a heater control unit for supplying power to the heater, a cylindrical radiation shield disposed above the silicon melt formed in the crucible and surrounding the periphery of the single crystal to be pulled up, a diameter measuring device for measuring the diameter of the single crystal to be pulled up, a radiation thermometer for measuring the temperature on the inner peripheral surface side of the radiation shield, and a controller for controlling the power supplied from the heater control unit to the heater. The controller is characterized in that it controls the power supplied from the heater control unit to the heater based on the diameter of the single crystal measured by the diameter measuring device and the temperature on the inner peripheral surface side of the radiation shield measured by the radiation thermometer.

[0014] In addition, it is provided with a wire for pulling up the single crystal and a pulling mechanism for winding up the wire and pulling up the grown single crystal. When pulling up the straight body part of the single crystal, it is desirable that the pulling mechanism winds up the wire so as to pull up the single crystal at a constant speed. Further, the radiation shield has an upper opening, a tapered portion that tapers from the upper opening toward the silicon melt, a terrace portion that extends horizontally inward from the lower end of the tapered portion and is formed in an annular shape, and a lower opening formed at the inner edge of the terrace portion. It is desirable that the radiation thermometer measures the temperature of the upper surface of the terrace portion. Further, it is desirable that the radiation thermometer measures the temperature near the lower end of the tapered portion on the upper surface of the terrace portion.

[0015] According to such a configuration, in the pulling of the straight body portion of the single crystal, the diameter of the single crystal to be grown is measured by a diameter measuring sensor, and the temperature on the inner peripheral surface side of the radiation shield is measured by a radiation thermometer. Then, using the measured crystal diameter and the measured temperature as inputs, the solid-liquid interface temperature for the target crystal diameter is determined, and the supply power amount output to the heater is controlled. Here, since the radiation thermometer measures the temperature on the inner peripheral surface side of the radiation shield, it is not affected by the reflection of the silicon melt or stray light, and can perform stable temperature measurement during the pulling process of the single crystal. As a result, the accuracy of the set temperature of the solid-liquid interface to be corrected can be improved, and the heater output can be controlled to suppress variations in the diameter of the single crystal.

[0016] Moreover, a method for manufacturing a single crystal according to the present invention, which is made to solve the above problems, is a method for manufacturing a single crystal in which a single crystal is pulled from a silicon melt accommodated in a crucible in a chamber by the Czochralski method. The method includes a step of forming a straight body portion of the single crystal while heating the silicon melt with a heater. In the step of forming the straight body portion of the single crystal, the method includes a step of measuring the diameter of the single crystal with a diameter measuring device, a step of measuring the temperature on the inner peripheral surface side of a cylindrical radiation shield disposed above the silicon melt formed in the crucible and surrounding the single crystal to be pulled with a radiation thermometer, and a step of controlling the power supplied to the heater based on the diameter of the single crystal measured by the diameter measuring device and the temperature on the inner peripheral surface side of the radiation shield measured by the radiation thermometer.

[0017] Further, in the step of forming the straight cylindrical portion of the single crystal, it is desirable to lift the single crystal at a constant speed. Also, in the step of measuring the temperature on the inner peripheral surface side of the radiation shield with a radiation thermometer, the radiation shield having an upper opening, a tapered portion that tapers from the upper opening toward the silicon melt, a terrace portion that extends horizontally inward from the lower end of the tapered portion and is formed in an annular shape, and a lower opening formed at the inner edge of the terrace portion is used, and it is desirable to measure the temperature of the upper surface of the terrace portion with the radiation thermometer. Also, in the step of measuring the temperature on the inner peripheral surface side of the radiation shield with a radiation thermometer, it is desirable to measure the temperature near the lower end of the tapered portion on the upper surface of the terrace portion with the radiation thermometer.

[0018] According to such a method, in pulling up the straight cylindrical portion of the single crystal, the diameter of the single crystal to be grown is measured by a diameter measuring sensor, and the temperature on the inner peripheral surface side of the radiation shield is measured by a radiation thermometer. Then, using the measured crystal diameter and the measured temperature as inputs, the supply power amount output to the heater is controlled. Here, since the radiation thermometer measures the temperature on the inner peripheral surface side of the radiation shield, it is less affected by the reflection of the silicon melt and stray light compared to the case of directly measuring the temperature of the silicon melt surface, and stable temperature measurement can be performed during the single crystal pulling process. As a result, the variation with respect to the target value of the diameter of the single crystal can be suppressed by controlling the heater output.

Effect of the Invention

[0019] According to the present invention, it is possible to provide a single crystal pulling apparatus and a single crystal manufacturing method capable of suppressing variations in the diameter of a single crystal.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0021] Hereinafter, the single crystal pulling apparatus and the method for manufacturing a single crystal according to the present invention will be described with reference to the drawings. Figure 1 is a cross-sectional view of the single crystal pulling apparatus according to the present invention. This single crystal pulling apparatus 1 includes a furnace body 10 formed by stacking a pull chamber 10b on a cylindrical main chamber 10a. Inside this furnace body 10, there is provided a carbon crucible (or graphite crucible) 2 that can rotate and move up and down around a vertical axis, and a quartz glass crucible 3 (hereinafter simply referred to as crucible 3) held by the carbon crucible 2. This crucible 3 is made to be rotatable around a vertical axis along with the rotation of the carbon crucible 2.

[0022] Also, below the carbon crucible 2, there are provided a rotation drive unit 14 such as a rotation motor that rotates the carbon crucible 2 around a vertical axis, and a lifting drive unit 15 that moves the carbon crucible 2 up and down. In addition, a rotation drive control unit 14a is connected to the rotation drive unit 14, and a lifting drive control unit 15a is connected to the lifting drive unit 15.

[0023] The single crystal pulling apparatus 1 also includes a heater 4 using a resistance heating method or a high frequency induction heating method for heating and melting the semiconductor raw material (raw material polysilicon) loaded in the crucible 3 to obtain a silicon melt M. In addition, in this embodiment, a heater control unit 4a that supplies power to the heater 4 applies, for example, a pulse width modulation (PWM) power control method. That is, the magnitude of the output voltage (the amount of supplied power) is controlled by the pulse width (ON period) of the switching cycle that repeats ON and OFF.

[0024] Further, the single crystal pulling device 1 includes a pulling mechanism 9 that winds up the wire 6 and pulls up the grown single crystal C. A seed crystal P is attached to the tip of the wire 6 that the pulling mechanism 9 has. A rotation drive control unit 9a that controls the rotation drive of the pulling mechanism 9 is connected to the pulling mechanism 9.

[0025] Also, above the silicon melt M formed in the crucible 3, a radiation shield 7 that surrounds the single crystal C is disposed. This radiation shield 7 has openings formed at the upper and lower portions, shields unnecessary radiant heat from the side heater 4, the silicon melt M, etc. to the growing single crystal C, and rectifies the gas flow in the furnace. Regarding the shape of the radiation shield 7, to describe in detail, as shown in FIG. 2, the radiation shield 7 has a tapered portion 7b that reduces in diameter from the upper opening 7a toward the silicon melt M (downward), and a terrace portion 7c that extends horizontally inward from the lower end of the tapered portion 7b and is formed in an annular shape. The single crystal is pulled up so as to pass through the lower opening 7d formed at the inner edge of the terrace portion 7c and the upper opening 7a.

[0026] Note that the radial length (width) of the terrace portion 7c is formed, for example, to be 10 to 150 mm so that reflection and stray light of the silicon melt M do not reach near the lower end 7c1 of the tapered portion 7b. Also, the gap between the lower opening 7d (lower end) of the radiation shield 7 and the melt surface is controlled to maintain a predetermined distance (for example, 50 mm) constant according to the desired characteristics of the single crystal to be grown.

[0027] Further, the single crystal pulling apparatus 1 is provided with an optical diameter measurement sensor (diameter measurement device) 16 such as a CCD camera for measuring the diameter of the single crystal being grown. A small window 10a1 for observation is provided on the upper surface portion of the main chamber 10a, and the position change of the crystal end (the position indicated by the broken line arrow) at the solid-liquid interface is detected from the outside of this small window 10a1.

[0028] In addition, the single crystal pulling apparatus 1 is provided with a radiation thermometer 17 for stably measuring a temperature close to the temperature of the boundary between the single crystal to be grown and the silicon melt, that is, the solid-liquid interface. As shown in FIG. 2, this radiation thermometer 17 is arranged to measure the temperature of the inner surface of the radiation shield 7, more specifically, the temperature of the vicinity 7c1 of the lower end of the tapered portion 7b on the upper surface of the terrace portion 7c. A small window 10a2 different from the small window 10a1 is provided on the upper surface portion of the main chamber 10a, and the temperature of the inner surface of the radiation shield 7 is measured from the outside of this small window 10a2. Incidentally, the emissivity of the radiation thermometer 17 can be set based on the result of previously performing a heat transfer simulation of the radiation shield 7.

[0029] In addition, this single crystal pulling apparatus 1 is provided with a controller 11 having a storage device 11a and an arithmetic control device 11b, and the rotation drive control unit 14a, the lifting drive control unit 15a, the rotation drive control unit 9a, the diameter measurement sensor 16, and the radiation thermometer 17 are respectively connected to the arithmetic control device 11b.

[0030] In the single crystal pulling apparatus 1 configured as described above, for example, when growing a single crystal C with a diameter of 305 mm, the pulling is performed as follows. That is, first, the crucible 3 is loaded with raw material polysilicon (for example, 460 kg), and the crystal growth process is started based on the program stored in the storage device 11a of the controller 11.

[0031] First, the inside of the furnace body 10 is made into a predetermined atmosphere (mainly an inert gas such as argon gas). For example, a furnace atmosphere with a furnace pressure of 65 torr and an argon gas flow rate of 90 l / min is formed. Then, with the crucible 3 rotating in a predetermined direction at a predetermined rotational speed (rpm), the raw material polysilicon loaded in the crucible 3 is melted by heating with the heater 4 to form a silicon melt M (step S1 in FIG. 3).

[0032] Also, the pulling-up conditions are adjusted with parameters such as the initial supply power to the heater 4 and the pulling-up speed, and the seed crystal P starts to rotate around its axis at a predetermined rotational speed. The rotational direction is opposite to that of the crucible 3. Then, the wire 6 is lowered and the seed crystal P is brought into contact with the silicon melt M. After melting the tip of the seed crystal P, necking is performed to form a neck portion P1 (step S2 in FIG. 3).

[0033] Then, the crystal diameter is gradually increased to form a shoulder portion C1 (step S3 in FIG. 3). Also, the controller 11 drives and controls the lifting drive unit 15 by the lifting drive control unit 15a, sets the pulling-up speed to be constant at, for example, 0.55 mm / min (step S4 in FIG. 3), and proceeds to the step of forming a straight body portion C2 that becomes the product portion (step S5 in FIG. 3).

[0034] Also, the controller 11 converts the change in the position of the crystal end at the solid-liquid interface detected by the diameter measurement sensor 16 into the crystal diameter, and obtains the temperature of the inner peripheral surface of the radiation shield 7 detected by the radiation thermometer 17 (step S6 in FIG. 3). When the value of the crystal diameter deviates from the target range (step S7 in FIG. 3), the supply power amount output to the heater 4 is determined by PID control so that the measured value of the crystal diameter falls within the target range, and the heater control unit 4a is operationally controlled (step S8 in FIG. 3).

[0035] For example, when the measured value of the crystal diameter is smaller than the target range, in order to lower the heating temperature by the heater 4, using the temperature of the inner peripheral surface of the radiation shield 7 as an input, the power supply amount by the heater control unit 4a is determined to be a smaller value by PID control. Conversely, when the measured value of the crystal diameter is larger than the target range, in order to increase the heating temperature by the heater 4, using the temperature of the inner peripheral surface of the radiation shield 7 as an input, the power supply amount by the heater control unit 4a is determined to be a larger value by PID control. Here, the heater control unit 4a first temporarily applies a pulsed voltage of a predetermined time and high voltage according to the power supply amount. Thereafter, a voltage corresponding to the determined power supply amount is applied. By doing so, it becomes possible to raise the temperature of the silicon melt M in a short time, and the temperature controllability can be made good.

[0036] Also, the temperature detected by the radiation thermometer 17 is the temperature of the inner peripheral surface of the radiation shield 7, and strictly speaking, it is not the temperature of the solid-liquid interface. However, when the temperature of the solid-liquid interface is directly measured by a radiation thermometer, the reflection of the silicon melt M and the influence of stray light are reflected in the measured value. By measuring the temperature of the inner peripheral surface of the radiation shield 7, more specifically, in the vicinity of the lower end of the tapered portion 7b in the terrace portion 7c, as in the configuration of the present invention, it is possible to make it less susceptible to the reflection of the silicon melt M and the influence of stray light, and stable temperature measurement can be performed during the single crystal pulling process. Further, by feeding back to the power supply to the heater 4 by the heater control unit 4a by PID control using this measured temperature and the measured crystal diameter as input values, it becomes possible to suppress variations in the crystal diameter.

[0037] When the straight barrel portion C2 is formed to a predetermined length (step S9 in FIG. 3), the process proceeds to the final tail portion process (step S10 in FIG. 3). In this tail portion process, the contact area between the lower end of the crystal and the silicon melt M gradually decreases, the single crystal C and the silicon melt M are separated, and a silicon single crystal is produced.

[0038] As described above, according to the present embodiment, in pulling up the straight cylindrical portion C2 of the single crystal, the pulling speed is made constant, the diameter of the single crystal C to be grown is measured by the diameter measuring sensor 16, and the temperature on the inner peripheral surface side of the radiation shield 7 is measured by the radiation thermometer 17. Then, using the measured crystal diameter and the measured temperature as inputs, the solid-liquid interface temperature for achieving the target crystal diameter is determined by PID control, and the supply power output to the heater 4 is controlled. Here, since the radiation thermometer 17 measures the temperature near the lower end of the tapered portion 7b in the terrace portion 7c of the radiation shield 7, it is not affected by the reflection of the silicon melt M or stray light, and stable temperature measurement can be performed during the pulling process of the single crystal. Further, by temporarily applying a pulsed voltage of a predetermined time and high voltage at the beginning, the time lag of the temperature change of the solid-liquid interface with respect to the fluctuation of the heater output can be reduced. As a result, variations with respect to the target value of the single crystal diameter can be suppressed.

[0039] In the above embodiment, the temperature near the lower end of the tapered portion 7b on the upper surface of the terrace portion 7c of the radiation shield 7 is measured by the radiation thermometer 17. However, in the present invention, it is not limited to this form. For example, the radiation thermometer 17 may measure the temperature of any part on the upper surface of the terrace portion 7c, or without being limited to the upper surface of the terrace portion 7c, the temperature of any part on the inner peripheral surface of the tapered portion 7b may be measured (that is, any device that measures the temperature on the inner peripheral surface side of the radiation shield 7 is acceptable). Also, in the above embodiment, the pulling speed is made constant, but the pulling speed may be varied instead of being constant.

Example

[0040] The single crystal pulling apparatus and the method for manufacturing a single crystal according to the present invention will be further described based on examples.

[0041] (Example 1) In Example 1, the quartz crucible with a diameter of 32 inches was filled with silicon raw materials and melted. Also, the pulling speed was kept constant at 0.6 mm / min during the formation of the straight body part, and seven P-type single crystals were continuously pulled up at a crystal rotation speed of 7 rpm and a crucible rotation speed of 1 rpm. The target value of the crystal diameter was set to 305 mm. With the configuration shown in Fig. 1, the diameter of the single crystal was measured, and the temperature on the inner circumferential side of the radiation shield (near the lower end of the tapered part in the terrace part) was measured using a radiation thermometer. The emissivity of the radiation thermometer was set based on the results of the heat transfer simulation of the radiation shield performed in advance. During the growth of the straight body part, PID control was performed with the measured temperature on the inner circumferential side of the radiation shield and the measured crystal diameter as inputs. When the measured crystal diameter deviated from the target range, the heater output was changed.

[0042] The graph in Fig. 4 shows the diameter variation with respect to the temperature measurement results. In the graph of Fig. 4, the horizontal axis is the measured temperature (°C) on the inner circumferential side of the radiation shield, and the vertical axis is the measured crystal diameter (mm). As shown in this graph, the diameter variation could be kept within ±1 mm. Also, as an evaluation of the pulled single crystal, an inspection for the presence or absence of defects by Secco etching was performed. LPD (Light Point Defect) of 19 nm or more was observed as minute voids. As shown in Table 1, in Example 1, 95% defect-free crystals were obtained with respect to the total length of the crystal. Also, divergence and hunting of the diameter of the single crystal did not occur.

[0043]

Table 1

[0044] (Comparative Example 1) In Comparative Example 1, the quartz crucible with a diameter of 32 inches was filled with silicon raw materials and melted in the same manner as in Example 1. Also, the pulling speed was kept constant at 0.6 mm / min during the formation of the straight body part, and seven P-type single crystals were continuously pulled up at a crystal rotation speed of 7 rpm and a crucible rotation speed of 1 rpm. The target value of the crystal diameter was set to 310 mm, and with the same configuration as in Example 1, the diameter of the single crystal was measured. Also, the temperature of the heater member located around the heater was measured using a radiation thermometer. During the growth of the straight body portion, PID control was performed with the measured temperature of the heater member and the measured crystal diameter as inputs, and the heater output was changed when the measured crystal diameter deviated from the target range.

[0045] The graph in Fig. 5 shows the diameter variation with respect to the temperature measurement results. In the graph of Fig. 5, the horizontal axis is the measured temperature (°C) of the heater member, and the vertical axis is the measured crystal diameter (mm). As shown in this graph, the diameter variation was as large as ±5 mm. Also, as an evaluation of the pulled single crystal, an inspection for the presence or absence of defects by Secco etching was performed. LPD (Light Point Defect) of 19 nm or more was observed as minute voids. As shown in Table 1, in Comparative Example 1, defect-free crystals were obtained at a rate of 80% with respect to the total length of the crystal, but the acquisition rate was lower than that in Example 1. Also, divergence and hunting of the diameter of the single crystal occurred three times.

[0046] From the results of the above examples, it was confirmed that according to the present invention, the variation in the diameter of the single crystal can be suppressed to be small.

Explanation of Signs

[0047] 1 Single crystal pulling apparatus 2 Carbon crucible 3 Quartz glass crucible 4 Heater 4a Heater control unit 6 Wire 7 Radiation shield 7a Upper opening 7b Taper portion 7c Terrace portion 7d Lower opening 10 Furnace body 11 Controller 16 Diameter measurement sensor (diameter measuring device) 17 Radiation thermometer M Silicon melt C silicon single crystal C2 straight body

Claims

1. In a single crystal pulling apparatus for pulling a single crystal from a silicon melt accommodated in a crucible in a chamber by the Czochralski method, a heater for heating the silicon melt, a heater control unit for supplying power to the heater, a cylindrical radiation shield disposed above the silicon melt formed in the crucible and surrounding the periphery of the single crystal to be pulled, a diameter measuring device for measuring the diameter of the single crystal to be pulled, a radiation thermometer for measuring the temperature on the inner peripheral surface side of the radiation shield, and a controller for controlling the power supplied by the heater control unit to the heater, wherein the controller controls the power supplied to the heater by the heater control unit based on the diameter of the single crystal measured by the diameter measuring device and the temperature on the inner peripheral surface side of the radiation shield measured by the radiation thermometer. The single crystal pulling apparatus is characterized by this.

2. A wire for pulling the single crystal, and a pulling mechanism for winding up the wire and pulling up the grown single crystal, when pulling up the straight body portion of the single crystal, the pulling mechanism winds up the wire so as to pull up the single crystal at a constant speed. The single crystal pulling apparatus according to claim 1 is characterized by this.

3. The radiation shield has an upper opening, a tapered portion that tapers in diameter from the upper opening toward the silicon melt, a terrace portion that extends horizontally inward from the lower end of the tapered portion and is formed in an annular shape, and a lower opening formed at the inner edge of the terrace portion, wherein the radiation thermometer measures the temperature of the upper surface of the terrace portion. The single crystal pulling apparatus according to claim 1 or claim 2 is characterized by this.

4. The radiation thermometer measures the temperature in the vicinity of the lower end of the tapered portion on the upper surface of the terrace portion. The single crystal pulling apparatus according to claim 3 is characterized by this.

5. A method for manufacturing a single crystal for pulling a single crystal from a silicon melt accommodated in a crucible in a chamber by the Czochralski method, comprising a step of forming a straight body portion of the single crystal while heating the silicon melt with a heater, in the step of forming the straight body portion of the single crystal, a step of measuring the diameter of the single crystal with a diameter measuring device, and a step of measuring the temperature on the inner peripheral surface side of a cylindrical radiation shield disposed above the silicon melt formed in the crucible and surrounding the periphery of the single crystal to be pulled with a radiation thermometer. a step of controlling the power supplied to the heater based on the diameter of the single crystal measured by the diameter measuring device and the temperature on the inner peripheral surface side of the radiation shield measured by the radiation thermometer; A method for manufacturing a single crystal, comprising the above. **Claim 6** In the step of forming the straight body portion of the single crystal, The method for manufacturing a single crystal according to claim 5, wherein the single crystal is pulled up at a constant speed. **Claim 7** In the step of measuring the temperature on the inner peripheral surface side of the radiation shield with a radiation thermometer, using the radiation shield having an upper opening, a tapered portion that tapers from the upper opening toward the silicon melt, a terrace portion that extends horizontally inward from the lower end of the tapered portion and is formed in a ring shape, and a lower opening formed at the inner edge of the terrace portion; The method for manufacturing a single crystal according to claim 5 or claim 6, wherein the temperature of the upper surface of the terrace portion is measured by the radiation thermometer. **Claim 8** In the step of measuring the temperature on the inner peripheral surface side of the radiation shield with a radiation thermometer, The method for manufacturing a single crystal according to claim 7, wherein the temperature near the lower end of the tapered portion on the upper surface of the terrace portion is measured by the radiation thermometer.

Images