WO2005075715A1

WO2005075715A1 - Single crystal semiconductor manufacturing method

Info

Publication number: WO2005075715A1
Application number: PCT/JP2005/001939
Authority: WO
Inventors: Hiroshi Inagaki; Masahiro Shibata; Shigeki Kawashima; Nobuyuki Fukuda
Original assignee: Komatsu Denshi Kinzoku Kabushiki Kaisha
Priority date: 2004-02-09
Filing date: 2005-02-09
Publication date: 2005-08-18
Also published as: TWI263710B; TW200526821A; JP2007223814A

Abstract

A single crystal semiconductor manufacturing method by which dislocation induction due to a sharp increase of the crystal diameter after the seed crystal is brought into contact with the melt is prevented by suppressing the variation in the temperature of the melt when a single crystal is pulled up with no dislocation without performing a necking process while using an impurity-added seed crystal, and the crystal is prevented from being thinned below a crystal diameter durable against the load. By keeping a magnetic field applied to the melt before the seed crystal is brought into contact with the melt, the variation in the temperature of the melt is suppressed when the single crystal starts to be pulled up, thereby preventing the crystal diameter from sharply increasing or decreasing.

Description

Specification

Method for manufacturing single crystal semiconductor

Technical field

[0001] The present invention relates to a method for manufacturing a single-crystal semiconductor such as single-crystal silicon using a CZ method (Czochralski method), in which a large-diameter and heavy-weight single-crystal semiconductor is manufactured without dislocations. It is about how you can do it.

Background art

[0002] One of the methods for producing single crystal silicon is the CZ method.

[0003] One of the problems that cannot be avoided when growing single-crystal silicon by the CZ method is "dislocation" that occurs at the solid-liquid interface of the seed crystal when the seed crystal lands on the melt. This dislocation occurs due to thermal stress induced in the seed crystal when the seed crystal immerses in the melt.

[0004] In order to pull out this dislocation outside the crystal, a so-called dash neck, which narrows the crystal diameter to 3-4 mm, is required. FIG. 8 shows a state in which a dash neck 21 having a crystal diameter of 3 to 4 mm is formed and dislocations are extracted outside the crystal.

[0005] In recent years, however, there has been a demand for the manufacture of large-diameter silicon wafers having a diameter of 300 mm or more, and it has been required that a large-diameter and heavy-weight single-crystal silicon ingot can be pulled up without any problem. If the diameter is reduced to about 3-4 mm, dislocations will be removed, but the diameter will be too small and it may not be possible to manufacture large-diameter, heavy-weight single-crystal silicon ingots without problems such as crystal falling. is there.

[0006] (Prior art 1)

Patent Document 1 described below discloses that a large-diameter, heavy-weight single-crystal silicon ingot is formed in a dislocation-free state without necking using a silicon seed crystal to which boron B is added as a high concentration impurity. The invention of lifting is described.

Patent Document 1: JP 2001-240493 A

Disclosure of the invention

Problems to be solved by the invention

[0007] The concentration of oxygen taken into single-crystal silicon is affected by convection generated in the melt. Are known to those skilled in the art. As a technique for suppressing the generation of convection in a quartz crucible, there is a technique called a magnetic field application pulling method. In this method, convection in the melt is suppressed by applying a magnetic field to the melt, and stable crystal growth is performed.

[0008] However, when a strong magnetic field is applied during the necking process, the dislocation moves to the vicinity of the crystal center, and a problem occurs that the dislocation does not escape to the side surface. This is presumed to be due to the following. That is, since the temperature fluctuation of the melt is suppressed by the effect of suppressing the convection of the magnetic field, the fluctuation of the crystal diameter and the pulling speed during netting is small, the solid-liquid interface shape becomes a stable upward convex shape, and the dislocation is solid-liquid. Since it moves in the direction perpendicular to the interface, it moves to the center of the crystal, making it difficult to eliminate dislocations.

[0009] On the other hand, even if the single crystal silicon ingot is pulled up by using the silicon seed crystal doped with the impurity boron B at a high concentration without performing the necking process by employing the above-mentioned conventional technology 1, the following problem occurs. Trouble may occur.

[0010] That is, in recent years, the amount of the melt has been increasing due to the large weight of the pulled crystal.

[0011] However, when the amount of the melt increases (especially, when the amount of the melt is 150 kg or more), the temperature fluctuation in the melt becomes large, and the time from when the seed crystal is immersed to when the process shifts to the shoulder process. The crystal diameter sharply increases with temperature fluctuations, and the occurrence of dislocations due to abnormal growth occurs. Conversely, temperature fluctuations cause the crystal diameter to be smaller than the diameter (withstand load) that can support the single crystal to be pulled. As a result, problems such as a reworking of the process power for immersing the seed crystal in the melt occur.

[0012] The present invention has been made in view of such circumstances, and when pulling a single crystal without dislocations using a seed crystal to which impurities are added, by suppressing the temperature fluctuation of the melt, It is an object of the present invention to avoid dislocation introduction due to a sudden increase in crystal diameter after crystal immersion and to avoid a crystal diameter smaller than the withstand load.

Means for solving the problem

[0013] The first invention is

In a single crystal semiconductor manufacturing method of manufacturing a single crystal semiconductor by dipping a seed crystal to which impurities are added into a melt in a crucible and pulling up the seed crystal, a magnetic field is applied to the melt. Process and A step of immersing the seed crystal in the melt;

A step of pulling up the single crystal semiconductor without performing necking after the seed crystal is immersed in the melt;

And a method for manufacturing a single crystal semiconductor including:

[0014] The second invention is based on the first invention,

Before applying the seed crystal to the melt, apply a magnetic field to the melt

It is characterized by.

[0015] In a third aspect, in the first aspect,

Magnetic field strength should be 1500 Gauss or more

It is characterized by.

[0016] In a fourth aspect, in the first aspect,

It is characterized in that boron is added to the seed crystal at a concentration of at least 8 atoms / cc as boron impurities.

[0017] In a fifth aspect, in the first aspect,

The minimum crystal diameter after the seed crystal has immersed in the melt must be 4 mm or more.

It is characterized by.

According to the present invention, the force before the seed crystal is immersed in the melt is applied to the melt by applying a magnetic field to suppress the temperature fluctuation of the melt at the start of the single crystal pulling, thereby increasing the crystal diameter rapidly. This is to prevent the crystal diameter from becoming thin.

[0019] There is a time lag from the start of applying a magnetic field to the melt until the effect of suppressing convection and suppressing temperature fluctuation in the melt is obtained. The effect can be obtained approximately 40 minutes after applying a magnetic field to the melt. Therefore, considering this time lag, it is desirable to apply a magnetic field to the melt a predetermined time before the seed crystal landing liquid so that the effect can be obtained at least at the time of the melt landing.

[0020] A magnetic field is continuously applied after the seed crystal liquid is applied, and it is necessary to apply the magnetic field at least until a transition to the shoulder process.

[0021] According to the present invention, the temperature fluctuation in the melt is suppressed, and dislocation introduction due to a sudden increase in the crystal diameter after the seed crystal deposition until the transition to the shoulder process is avoided. . [0022] Further, it is possible to prevent the crystal diameter from being reduced to a diameter (withstand load) capable of supporting the crystal by raising the crystal diameter due to temperature fluctuation.

According to the present invention, since a dash neck is not required, after the seed crystal is immersed in the melt, the process may be immediately shifted to a so-called shoulder process in which the crystal is pulled up while gradually increasing its diameter, As shown in Fig. 9, after deposition, the crystal growth part 22 (for example, about 50 mm in length) was pulled up with a substantially constant diameter, and after confirming that the melt temperature was appropriate, the process was shifted to the shoulder process. Is also good.

[0024] It is desirable that the concentration of impurity boron B to be added to the seed crystal is lel8atoms / cc or more (the fourth invention). This is because the interface between the seed crystal and the newly formed crystal after landing was evaluated by X-rays after pulling up.When impurity boron B was added to the seed crystal at lel8 atoms / cc or more, dislocation was introduced. It is a cara that is not seen.

Brief Description of Drawings

FIG. 1 is a view showing a single crystal bow I raising apparatus according to an embodiment.

FIG. 2 is a graph showing the relationship between the temperature difference between a seed crystal and a melt and the maximum decomposition shear stress.

FIG. 3 is a graph showing the relationship between the seed crystal diameter, the impurity concentration in the seed crystal, and the allowable temperature difference.

[Fig. 4] Fig. 4 is a table showing the results of experiments performed to compare the case where a magnetic field was applied to the melt with the case where a magnetic field was not applied.

FIG. 5 is a view showing a single crystal pulling apparatus different from FIG. 1.

FIG. 6 is a table showing a relationship between various elements added to a seed crystal and a concentration range in which heat shock dislocation is not introduced.

FIG. 7 is a graph showing a relationship between a silicon crystal diameter and a withstand load.

FIG. 8 is a view showing a dash neck portion.

FIG. 9 is a view showing a crystal growth part after liquid landing.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an apparatus according to an embodiment will be described with reference to the drawings.

FIG. 1 is a side view of the configuration of the embodiment. As shown in FIG. 1, the single crystal pulling apparatus 1 of the embodiment includes a CZ furnace (chamber) 2 as a single crystal pulling container. The single crystal pulling apparatus 1 of FIG. 1 is an apparatus suitable for producing a large-diameter (for example, 300 mm in diameter) and heavy single-crystal silicon ingot.

[0029] In the CZ furnace 2, a quartz crucible 3 for melting a polycrystalline silicon raw material and storing the melt as a melt 5 is provided. In order to pull up single crystal silicon having a diameter of 300 mm, about 30 Okg of polycrystalline silicon is charged into the quartz crucible 3. The outside of the quartz crucible 3 is covered with a graphite crucible 11. A cylindrical main heater 9 that heats and melts the polycrystalline silicon raw material in the quartz crucible 3 is provided outside and laterally of the quartz crucible 3. At the bottom of the quartz crucible 3, an annular bottom heater 19 is provided to supplementally heat the bottom of the quartz crucible 3 to prevent the melt 5 at the bottom of the quartz crucible 3 from solidifying. The outputs (power; kW) of the main heater 9 and the bottom heater 19 are independently controlled, and the heating amount for the melt 5 is independently adjusted. For example, the output of the main heater 9 and the bottom heater 19 is controlled such that the temperature of the melt 5 is detected, and the detected temperature is used as a feedback amount so that the temperature of the melt 5 reaches the target temperature.

In the embodiment, any heating means other than the heater may be used as the heating means for heating the melt 5 from the outside by the heaters 9 and 19. For example, a method by electromagnetic heating or heating by laser irradiation may be employed.

[0031] A heat retaining cylinder 13 is provided between the main heater 9 and the inner wall of the CZ furnace 2.

[0032] Above the quartz crucible 3, a pulling mechanism 4 is provided. The pulling mechanism 4 includes a pulling shaft 4a and a seed chuck 4c at the tip of the pulling shaft 4a. The seed crystal 14 is gripped by the seed chuck 4c. Here, the pulling shaft 4a is, for example, a shaft or a wire, and is pulled up by the shaft or wound up by the wire.

[0033] Polycrystalline silicon (Si) is heated and melted in quartz crucible 3. When the temperature of the melt 5 is stabilized, the pulling mechanism 4 operates to pull single crystal silicon (single crystal silicon ingot) from the melt 5. That is, the pulling shaft 4a is lowered, and the seed crystal 14 held by the seed chuck 4c at the tip of the pulling shaft 4a is immersed in the melt 5. After the seed crystal 14 is adapted to the melt 5, the pulling shaft 4a is raised. Single crystal silicon grows as the seed crystal 14 held by the seed chuck 4c rises. At the time of pulling up, the quartz crucible 3 is To rotate at a rotation speed of ω1. The pulling shaft 4a of the pulling mechanism 4 is in the opposite direction to the rotating shaft 10, and rotates at the rotation speed ω2 in the same direction.

The rotating shaft 10 can be driven in the vertical direction, and the quartz crucible 3 can be moved up and down to an arbitrary position.

By shutting off the inside of the CZ furnace 2 from the outside air, the inside of the furnace 2 is maintained at a vacuum (for example, about 20 Torr). That is, the CZ furnace 2 is supplied with an argon gas 7 as an inert gas, and the exhaust locus of the CZ furnace 2 is also exhausted by the pump. Thereby, the pressure in the furnace 2 is reduced to a predetermined pressure.

Various evaporants are generated in the CZ furnace 2 during the single crystal pulling process (one batch). Therefore, the argon gas 7 is supplied to the CZ furnace 2 and exhausted together with the evaporant to the outside of the CZ furnace 2 to remove the evaporant from the CZ furnace 2 to make the CZ furnace 2 clean. The supply flow rate of the argon gas 7 is set for each process in one batch.

[0037] The melt 5 decreases as the single crystal silicon is pulled up. As the melt 5 decreases, the contact area between the melt 5 and the quartz crucible 3 changes, and the amount of oxygen dissolved from the quartz crucible 3 changes. This change affects the oxygen concentration distribution in the single crystal silicon to be pulled. Therefore, in order to prevent this, a polycrystalline silicon material or a single crystal silicon material may be additionally supplied into the quartz crucible 3 in which the melt 5 has been reduced after or during the pulling.

[0038] Above the quartz crucible 3 and around the single crystal silicon, a heat shielding plate 8 (gas rectifying cylinder) having a substantially inverted truncated cone shape is provided. The heat shield plate 8 is supported by the heat retaining cylinder 13. The heat shield plate 8 guides the argon gas 7 as a carrier gas supplied from above into the CZ furnace 2 to the center of the melt surface 5a, and further passes through the melt surface 5a to form a peripheral portion of the melt surface 5a. Lead to. Then, the argon gas 7 is exhausted from the melt 5 together with the gas evaporated from the melt 5 and the exhaust port provided at the lower part of the CZ furnace 2. For this reason, the gas flow velocity on the liquid surface can be stabilized, and the oxygen evaporated from the melt 5 can be kept in a stable state.

Further, the heat shield plate 8 heat-insulates and shields the seed crystal 14 and single crystal silicon grown by the seed crystal 14 from radiant heat generated in a high-temperature portion such as the quartz crucible 3, the melt 5, and the main heater 9. Cover up. The heat shield plate 8 prevents impurities (for example, silicon oxide) generated in the furnace from adhering to the single crystal silicon and hindering the growth of the single crystal. The size of the gap G between the lower end of the heat shield plate 8 and the melt surface 5a raises and lowers the rotating shaft 10 and the quartz It can be adjusted by changing the vertical position of the crucible 3. Alternatively, the gap G may be adjusted by moving the heat shield plate 8 up and down by a lifting device.

[0040] A magnet 20 for applying a magnetic field (transverse magnetic field) to the melt 5 in the quartz crucible 3 is provided outside and around the CZ furnace 2!

FIG. 2 shows the temperature difference ΔΤ (° C.) between the tip surface of seed crystal 14 and melt 5 (liquid contact surface) when seed crystal 14 is immersed in melt 5, It shows the relationship between the maximum decomposition shear stress and MRSS (MPa). Here, the maximum decomposition shear stress MRSS (MPa) in the seed crystal 14 is the maximum value of the thermal stress applied to the seed crystal 14 when the melt is immersed in the melt 5, and dislocation due to heat shock is introduced into the seed crystal 14. It shows the index to be used. Figure 2 plots the temperature difference ΔΤ calculated by the heat transfer analysis calculation (FEMAG) and the maximum decomposition shear stress MRSS calculated by the stress analysis (FEMAG).

As shown in FIG. 2, as the temperature difference ΔΤ becomes smaller, the maximum decomposition shear stress MRSS in the seed crystal 14 becomes smaller, and dislocation due to a thermal shock is introduced into the seed crystal 14.

On the other hand, in the earlier application (Japanese Patent Application No. 2002-204178) of the present applicant, the concentration C of the impurity (for example, boron B) added to the seed crystal 14 and the size (diameter D) of the seed crystal 14 The relationship between the critical decomposition shear stress (CRSS; MPa) and the allowable temperature difference ATc was disclosed.

That is, FIG. 3 shows the allowable temperature between the temperature of the tip of the seed crystal 14 and the temperature of the melt 5 (liquid contact surface) at the time of liquid landing, with the diameter D (mm) of the seed crystal 14 taken on the horizontal axis. The difference ATc is plotted on the vertical axis, and the correspondence between the diameter D and the allowable temperature difference ATc is shown by characteristics Ll, L2, and L3. As shown by the characteristics Ll, L2, and L3, a substantially inverse relationship is established between the seed crystal diameter D and the allowable temperature difference ATc. That is, as the seed crystal diameter D increases, the thermal shock stress applied to the seed crystal 14 at the time of liquid contact increases, and the allowable temperature difference ATc needs to be reduced accordingly.

Here, the allowable temperature difference ATc is an upper limit temperature difference at which dislocations are not introduced into seed crystal 14.

The characteristics Ll, L2, and L3 indicate the difference in the magnitude of the critical decomposition shear stress (CRSS; MPa), which is one of the indexes of the mechanical strength of the seed crystal 14. Critical decomposition shear stress (CRSS) is the critical stress beyond which dislocations are introduced into the seed crystal 14. In the figure, the characteristic L1 has the smallest critical decomposition shear stress (CRSS) (5 MPa), and the characteristic L2 is the characteristic. L beams also have a large critical decomposition shear stress (CRSS) (lOMPa), and characteristic L3 has the highest critical decomposition shear stress (CRSS) ヽ (15MPa).

[0047] The critical decomposition shear stress (CRSS) varies depending on the type and concentration C of impurities added to the seed crystal 14. In the present embodiment, boron B is assumed as the type of impurity.

[0048] As the concentration C of the impurity added to the seed crystal 14 increases, the critical decomposition shear stress (CRSS) increases. As the concentration C of the impurity added to the seed crystal 14 increases to Cl, C2, and C3, the characteristics change to L1, L2, and L3. Note that FIG. 3 shows the case where the impurity concentration C is three types as a representative, but as the impurity concentration C changes in more steps and continuously, the characteristics become multi-step or It changes continuously.

[0049] Therefore, if the diameter D of the seed crystal 14 is, for example, equal to 3, the impurity concentration C changes to LI, L2, and L3 as the impurity concentration C increases to Cl, C2, and C3. growing. If the allowable temperature difference ATc is, for example, the same value ATcO, the diameter D of the seed crystal 14 changes to L1, L2, L3 as the diameter D1, D2, D3 increases, so that the impurity concentration C is changed to Cl, C2, C3. It should just be big.

[0050] The force described in the case where the type of impurity is boron B The same relationship can be established when various impurities other than boron B, such as germanium Ge and indium In, are added to the seed crystal 14.

[0051] Accordingly, the allowable temperature difference ATc when the seed crystal 14 is added with the predetermined concentration C and the size (diameter) of the seed crystal 14 is the predetermined value D is calculated using the characteristics Ll and L2 shown in FIG. By adjusting the power of each of the heaters 9 and 19 so that the temperature difference ΔΤ between the seed crystal 14 and the melt 5 at the time of immersion is equal to or less than the allowable temperature difference ATc, It is possible to prevent dislocations from being introduced into the seed crystal 14 without performing necking.

[0052] Impurity boron B force 5el8atoms / cc added silicon seed crystal 14 with a diameter of 7mm, the allowable temperature difference ATc is 100 ° C, and the temperature difference between seed crystal 14 and melt 5 at the time of liquid contact Δ 液However, if the power of each of the heaters 9 and 19 can be adjusted so as to be equal to or smaller than the allowable temperature difference ATc (100 ° C.), dislocation-free operation can be stably performed without performing necking.

FIG. 4 shows the results of an experiment in which the effect of the magnetic field force applied to the melt 5 on the temperature difference ΔΤ was examined. In the experiment, impurity boron B force 5el8atoms / cc added diameter 7mm (Allowable temperature difference ATc is 100 ° C.), the power input to the bottom heater 19 (Kw) when the silicon seed crystal 14 is immersed in the melt 5, and the power input to the main heater 9 (Kw). Kw) was varied (1)-(6), and a magnetic field of 3000 (Gauss) was applied to the melt 5 by the magnet 20 (test (4)-(6)). In the case where no magnetic field was applied (test (1)-(3)), it was examined whether or not a force for introducing dislocations into the silicon seed crystal 14 was determined. In FIG. 4, the ones in which dislocations are introduced into the seed crystal 14 and single-crystal silicon are dislocated are indicated by X, and those in which no dislocations are introduced into the seed crystal 14 and single-crystal silicon is dislocated. Is marked with a triangle. In the experiment, 300 kg of polycrystalline silicon was charged and single crystal silicon having a diameter of 300 mm was pulled up. In the experiment, the electric power supplied to the bottom heater 19 was fixed to each value (0 Kw, 10 Kw, 35 Kw), and the liquid contact surface of the melt 5 on which the seed crystal 14 was contacted was set to the target temperature (for example, 1340 ° C.). ), The power supplied to the main heater 9 was controlled by a closed loop control system.

As shown in FIG. 4, when no magnetic field is applied to the melt 5 (test (1) -one (3)), the power supplied to the bottom heater 19 is reduced to 0 (Kw), Only the test (3) in which the input power to the power supply was adjusted to 138 (Kw) had a temperature difference of 95.6 (° C) below the allowable temperature difference ΔTc (100 ° C). Confirmed force Other than that, the power input to the bottom heater 9 was set to a higher value than OKw (10Kw, 35Kw). For tests (1) and (2), the temperature difference (111.1) exceeding the allowable temperature difference ATc ° C, 103.2 ° C).

[0055] On the other hand, when a magnetic field is applied to the melt 5 (test (4) -1 (6)), regardless of the input power (input power ratio) to the bottom heater 19 and the main heater 9 Temperature difference less than the permissible temperature difference ΔΤ c (100 ° C) (92, 2 ° C, 82.5 ° C, 78.5 ° C), and no dislocations at all test levels. A dagger was confirmed. In particular, in the test in which the power supplied to the bottom heater 9 was set to a value higher than OKw (10 Kw, 35 Kw), dislocations were observed when no magnetic field was applied, whereas no dislocation was observed when a magnetic field was applied. The difference of dislocation was confirmed. Note that FIG. 2 is a plot showing a point where the dislocation-free transfer is realized in FIG. 4 (marked with 〇) and a point where the dislocation is formed (marked with X).

By applying a magnetic field to the melt 5 as described above, regardless of the heater input power The reason why dislocation-free is easily realized is explained as follows.

That is, by applying a magnetic field to the melt 5, convection in the melt 5 is suppressed. As a result, heat transfer in the melt 5 is suppressed, the temperature difference in the lateral direction of the melt 5 in FIG. 1 increases, and the portion of the melt 5 where the seed crystal 14 lands (the immersion surface) The temperature drops. As a result, the power input to the main heater 9 starts to increase in order to maintain the target temperature of the liquid landing surface of the melt 5. When the power supplied to the main heater 9 increases, the temperature of the seed crystal 14 increases due to the increase in radiant heat, and the temperature of the seed crystal 14 approaches the temperature of the melt 5 (which is higher than the temperature of the seed crystal 14). The difference Δ 縮小 is reduced. For this reason, the maximum decomposition shear stress MRSS (M Pa) in the seed crystal 14, that is, the maximum value of the thermal stress associated with the liquid landing, is reduced, and dislocations are more introduced.

[0058] The strength of the magnetic field applied to the melt 5 is preferably 1500 (Gauss) or more. This is because, when the magnetic field strength is 1000 to 1500 (Gauss), an unstable part where the temperature fluctuation becomes large in the melt 5 appears, and there is a possibility that a problem that the diameter of the crystal fluctuates may occur. Below Gauss), the effect of suppressing the convection is small, and the controllability of the crystal diameter is poor.

In this embodiment, a magnetic field is applied before the seed crystal 14 lands on the melt 5.

[0060] This is because a magnetic field is applied to the melt 5 before the seed crystal 14 lands on the melt 5, thereby suppressing temperature fluctuation of the melt 5 at the time of starting pulling of the single crystal silicon. It is intended to avoid a sudden increase in crystal diameter or a decrease in crystal diameter.

There is a time lag from when the magnetic field is applied to the melt 5 to when the effect of suppressing the convection and suppressing the temperature fluctuation in the melt 5 is obtained. The effect can be obtained approximately 40 minutes after applying a magnetic field to the melt 5. Therefore, considering this time lag, it is desirable to apply a magnetic field to the melt 5 a predetermined time before the seed crystal landing liquid so that the effect can be obtained at least at the time of the melt landing liquid.

[0062] The magnetic field is continuously applied after the seed crystal liquid is applied, and it is necessary to apply the magnetic field at least until the transition to the shoulder process. It is desirable to continue applying a magnetic field until the formation of the straight body is completed.

(Example 1)

In Example 1, a 7 mm-diameter silicide was added with impurity boron B power of 5el8atoms / cc. Con seed crystal 14 was used (allowable temperature difference ΔTc was 100 ° C.).

[0063] At least 40 minutes before the seed crystal 14 lands on the melt 5, the application of a magnetic field to the melt 5 is started by the magnet 20 until the growth of the silicon single crystal is completed. The magnetic field (transverse magnetic field) with a magnetic field strength of 3000 (Gauss) was continued to be applied until the formation of the straight body portion was completed. That is, the strength of the magnetic field applied before the seed crystal 14 lands is the same as the strength of the magnetic field applied during single crystal growth.

When the seed crystal 14 lands on the melt 5, the power supplied to the bottom heater 19 is fixed at 35 Kw.

[0065] Then, the electric power supplied to the main heater 9 is adjusted by a closed loop control system so that the surface temperature at which the seed crystal 14 of the melt 5 lands is at the target temperature (for example, 1340 ° C). Controlled. Therefore, the input power (Kw) to the bottom heater 19 and the input power (Kw) to the main heater 9 become 35 (Kw) and 112 (Kw), respectively, as in the test (4) shown in FIG. The temperature difference ΔT between the seed crystal 14 and the melt 5 at the time of the liquid becomes a value (92.2 ° C) or less of the allowable temperature difference ΔTc (100 ° C), and the dislocation into the seed crystal 14 The introduction was suppressed.

[0066] After the seed crystal 14 was immersed in the melt 5, single-crystal silicon was pulled up without performing necking. After the seed crystal is immersed, the temperature of the melt 5 reaches the target temperature while the power (Kw) applied to the bottom heater 19 is maintained at the same power 35 (Kw) as when the single crystal silicon is immersed while pulling the single crystal silicon. Thus, the power supplied to the main heater 9 was controlled.

As a result, single crystal silicon could be grown without dislocations without performing necking.

[0068] According to the present embodiment, since a dash neck is not required, after the seed crystal 14 is immersed in the melt 5, the process may be immediately shifted to a so-called shoulder process in which the crystal is pulled up while gradually increasing its diameter. Then, as shown in Fig. 9, the crystal growth part 22 (e.g., about 50 mm in length) was pulled up with a substantially constant diameter after liquid contact, and after confirming that the melt temperature was appropriate, the process shifted to the shoulder process. You may. It is desirable that the diameter (minimum crystal diameter) of the crystal growth part 22 be 4 mm or more.

[0069] In particular, according to the present embodiment, when the seed crystal 14 is immersed in the melt 5, the temperature fluctuation in the melt 5 is suppressed, so that after the seed crystal immersion, the process proceeds to the shoulder process. Until the crystal diameter The introduction of dislocations due to the sudden increase was avoided. Further, it was avoided that the crystal diameter was raised to a value smaller than the (load-bearing) diameter capable of supporting the crystal by raising the crystal diameter due to temperature fluctuation.

FIG. 7 is a graph showing the relationship between the diameter of a silicon single crystal and the withstand load. The load capacity is determined according to the diameter of the silicon single crystal (the diameter that becomes the narrowest before the transition to the shoulder process). According to the present embodiment, the diameter of the silicon single crystal is maintained at the diameter of the seed crystal 14 which does not become thinner than the diameter of the seed crystal 14, so that the weight (diameter) of the silicon single crystal to be pulled is reduced. If the diameter of the seed crystal 14 is set accordingly, a large-diameter and heavy silicon single crystal can be reliably pulled without breaking.

Further, according to the present embodiment, non-dislocation of single crystal silicon that can be pulled up can be realized while the power applied to the bottom heater 19 is unchanged during and after the seed crystal liquid landing, and the heater Adjustment work is simplified, and the burden on the operator is reduced. In addition, according to the present embodiment, the power applied to the bottom heater 19 is maintained at a high value (35 Kw) which is equal to or higher than a certain level at the time of the seed crystal landing liquid and thereafter, while the single crystal silicon is pulled up. Since the dislocation-free dislocation is realized, it is possible to avoid a large change in the diameter of the single crystal silicon to be pulled up by increasing the power supplied to the bottom heater 19 after the seed crystal liquid is deposited.

When the seed crystal 14 lands on the melt 5, the heat shield plate 8 is raised by the above-described elevating device so that more radiant heat is applied to the seed crystal 5, The difference ΔΤ may be further reduced.

[0073] Further, by keeping the difference between the concentration of the impurity added to seed crystal 14 and the concentration of the impurity in melt 5 at a certain level or less, not only dislocation due to heat shock but also the melting of seed crystal 14 is suppressed. It is desirable to avoid the introduction of dislocations (misfit dislocations) due to lattice mismatch at the joint surface with liquid 5.

[0074] The type and concentration of impurities to be added to the melt 5 side are determined by specifications specified by the semiconductor device maker as the customer. Specifically, for impurity B, a predetermined concentration within the range of 5el4-2el9atoms / cc, for impurity P, a predetermined concentration of lel4-8el8atoms / cc, and for impurity Sb, 2el7-el9atoms. If it is a predetermined concentration within the range of / cc and impurity As, it is a predetermined concentration within the range of 5el8-le20atoms / cc. [0075] In order to suppress dislocation due to lattice mismatch, the impurity species and impurities on the melt 5 side should be adjusted so that the lattice mismatch rate at the junction between the seed crystal 14 and the single crystal silicon is 0.01% or less. It is desirable to use a seed crystal 14 in which the impurity seed and the addition concentration are adjusted in advance according to the concentration.

In the present embodiment, the strength of the magnetic field applied before the seed crystal 14 lands is the same as the strength of the magnetic field applied during the growth of the single crystal. The intensity of the magnetic field applied to the substrate may be greater than the intensity of the magnetic field applied during single crystal growth.

Further, in the first embodiment, the description has been made on the assumption that the silicon seed crystal 14 having a diameter of 7 mm is used. However, if the silicon seed crystal has a diameter of 4 mm or more, the necking process is similarly performed. Single crystal silicon can be grown without dislocations without dislocation. In order to pull a single crystal silicon having a diameter of 300 mm exceeding a weight of 200 kg, the diameter of the silicon seed crystal 14 is desirably 5 mm or more.

(Example 2)

Further, single crystal pulling apparatus 1 shown in FIG. 5 may be used instead of single crystal pulling apparatus 1 in FIG.

In the apparatus shown in FIG. 5, the arrangement of the bottom heater 19 is omitted, and the main heater 9 is divided into two upper and lower heaters 9 a and 9 b along the vertical direction of the quartz crucible 3. The heaters 9a and 9b can independently adjust the heating amount of the quartz crucible 3, that is, the output. In the embodiment device, the heater 9 may be divided into three or more forces that are divided into two stages.

[0080] Even in the multi-heater having such a configuration, similarly to the first embodiment, if a magnetic field is applied to the melt 5 before the seed crystal 14 lands on the melt 5, the same as in the first embodiment. In addition, large-diameter and heavy single-crystal silicon can be reliably pulled up without dislocation and without breaking without necking.

(Example 3)

In the above-described embodiment, the description has been made on the assumption that the single crystal pulling apparatus 1 is provided with a multi-heater. However, when the single crystal pulling apparatus 1 is provided with a single heater, that is, in the case of FIG. Similarly, before applying liquid to melt 5, the magnetic field is applied to melt 5, and in the same way, it breaks without dislocation without necking treatment. The single crystal silicon having a large diameter and a large weight can be surely pulled up without performing.

[0082] In the above-described embodiment, even when various impurities such as gallium Ga and indium In other than boron B are added to the seed crystal 14, the same applies to the case where the kind of impurity is boron B. The introduction of dislocations into the seed crystal due to shock is suppressed, and single crystal silicon can be grown without dislocations.

FIG. 6 shows a concentration range in which when various elements are added to the seed crystal 14, introduction of dislocations into the seed crystal due to heat shock is suppressed. That is, in the case of impurity B, lel8 atoms / cc or more may be added. This was evaluated by X-ray evaluation of the interface between the seed crystal 14 after pulling and the newly formed crystal after contact with liquid, and found that when boron B was added to the seed crystal 14 by lei 8 atoms / cc or more. Is the force that did not show the introduction of dislocations. In addition, if it is impurity Ga, it can be added by adding 5el9atoms / cc or more.If it is In, it can be added by adding lel6 atoms / cc or more.If it is impurity P, it can be added by lel9atoms / cc or more. If the impurity is As, it should be added with 5el9atoms / cc or more.If the impurity is Sb, it should be added with lel9atoms / cc or more.If it is Ge, the impurity should be 5el9atoms / cc or more. If it is impurity N, it should be added at 5el3atoms / cc or more. If it is impurity C, it should be added at 8el6atoms / cc or more.

In the above description, the addition of a high concentration of impurities to the seed crystal 14 and the application of a magnetic field to the melt 5 are performed in a dislocation-free state without performing necking treatment. A large-diameter, heavy-weight single crystal silicon ingot is pulled up.By adding a high concentration of impurities to the seed crystal 14, dislocation due to heat shock can be prevented. It is also possible to implement only adding impurities to seed crystal 14 at a high concentration without applying voltage.

[0085] In the above description, the allowable temperature difference is taken as an example of the diameter D as the size of the seed crystal 14.

The force described in the case of obtaining ΔTc The other allowable temperature difference ΔTc may be obtained using the area of the tip surface of the seed crystal 14 and the like as the size of the seed crystal 14.

Claims

The scope of the claims

[1] A method for manufacturing a single crystal semiconductor, in which a seed crystal to which an impurity is added is immersed in a melt in a crucible and a single crystal semiconductor is manufactured by pulling up the seed crystal,

Applying a magnetic field to the melt;

A step of immersing the seed crystal in the melt;

A method for producing a single crystal semiconductor, comprising:

[2] Before applying the seed crystal to the melt, apply a magnetic field to the melt.

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

[3] The strength of the magnetic field must be greater than 1500 Gauss

The method for producing a single crystal semiconductor according to claim 1.

[4] The method for producing a single crystal semiconductor according to [1], wherein the impurity is added to the seed crystal at a concentration of boron B force of lel8 atoms / cc or more.

[5] The minimum crystal diameter after the seed crystal has immersed in the melt must be 4 mm or more.