JPH10324592A - Apparatus for pulling up single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems associated with the conventional apparatus for pulling up single crystals by a DLCZ method, i.e., the control of the thickness and melting rate of a solid layer is difficult and it takes time for formation of the solid layer with the conventional apparatus as these apparatus are not provided with cooling means; heaters are liable to breakage in case a molten layer solidifies as the heaters are fixed to the apparatus; and the heat history of the pulled up single crystal is not made uniform and the deposition state of oxygen is nonuniform in the heat treatment of a wafer after the manufacture of the wafer as the apparatus are not provided with means for applying the heat treatment to the single crystal to be pulled up. SOLUTION: This apparatus for pulling up the single crystal includes a crucible 11 to be packed with raw materials for the crystal and a main heater 12a and sub-heater 12b disposed on the circumference of this crucible 11. Moving means for making these heaters movable in a vertical direction or radial direction are attached to at least one stage of the heaters of the main heater 12a and the sub-heater 12b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal pulling apparatus used for pulling a single crystal by a molten layer method, and more particularly, to a silicon single crystal used as a semiconductor material for LSI, CCD, solar cell, etc. And the like.

[0002]

2. Description of the Related Art There are various methods for growing a single crystal. One of the methods is the Czochralski method (hereinafter referred to as a C method).
Z method). FIG. 20 is a cross-sectional view schematically showing a crystal pulling apparatus used in the conventional CZ method. In the figure, reference numeral 31 denotes a crucible. The crucible 31 has a bottomed cylindrical inner container 31a made of quartz, and a bottomed cylindrical outer container 31 made of graphite fitted outside the inner container 31a.
The crucible 31 is supported by a support shaft 38 which rotates at a predetermined speed in the direction of the arrow in the figure. A heater 32 of a resistance heating type is arranged outside the crucible 31, and a heat retaining tube 37 is arranged concentrically outside the heater 32, and a crystal raw material melted by the heater 32 is placed in the crucible 31. Of the melt 33 is filled. On the central axis of the crucible 31, a lifting shaft 34 composed of a lifting rod, a wire, or the like that rotates at a predetermined speed in the same direction or in the opposite direction with the same axis as the supporting shaft 38 is suspended. A seed crystal 35 a is attached to a seed chuck 35 disposed at the end of the seed chuck 35. The seed crystal 35 a is brought into contact with the surface of the
Is pulled upward while rotating in accordance with the crystal growth, whereby the melt 33 is solidified and the single crystal 36 is grown.

When a semiconductor crystal is grown by this pulling method, an impurity element is added (doped) to the melt 33 before the pulling in order to adjust the electric resistivity and the electric conduction type of the single crystal 36. However, in the ordinary CZ method, a so-called segregation phenomenon occurs in which the added impurity concentration changes along the crystal growth direction of the single crystal 36, and as a result, a single crystal having uniform electric characteristics in the crystal growth direction. There was a problem that crystal 36 could not be obtained.

[0004] This segregation is caused by the impurity concentration Cs in the single crystal 36 at the interface between the melt 33 and the single crystal 36 during solidification.
This is because the ratio Cs / Cl (effective segregation coefficient Ke) between the temperature and the impurity concentration Cl in the melt 33 is not 1. For example, when the effective segregation coefficient Ke <1, the impurity concentration in the melt 33 gradually increases as the single crystal 36 grows, and segregation occurs in the single crystal 36. Therefore, the yield based on the electric resistivity of the single crystal pulled up by such a method becomes low.

As one of the methods for growing a single crystal while suppressing the segregation of impurities described above, a molten layer method (hereinafter referred to as D
LCZ method).

FIG. 21 is a cross-sectional view schematically showing a single crystal pulling apparatus used in the DLCZ method. The raw material at the upper part of a crucible 41 having the same structure as that shown in FIG. To form a molten layer 43 in the upper layer and a solid layer 49 in the lower layer. Then, while the solid layer 49 is gradually melted with the pulling, the single crystal 46 is grown by the same method as the pulling method by the CZ method described above.

[0007] As the DLCZ method, two methods have been proposed so far, namely, a constant molten layer thickness method and a molten layer thickness changing method.

In the molten layer thickness constant method, when the single crystal 46 is pulled, regardless of the amount of the pulled single crystal 46,
In this method, the power of the heater 42 is adjusted so as to keep the volume of the molten layer 43 constant within 1 and the solid layer 49 is melted. Further, in this method, while the solid layer 49 containing no impurities is further melted as the single crystal is pulled, the impurities are continuously added to keep the impurity concentration of the molten layer 43 constant (Japanese Patent Publication No. Sho 34). No. 8242, Japanese Patent Publication No. 62-880, etc.), and the solid layer 49 is made to contain impurities first, and the impurity concentration of the molten layer 43 during single crystal pulling is kept constant without adding impurities. (Japanese Patent Publication No. Sho 62-880, JP-A-63-252)
No. 989).

On the other hand, in the molten layer thickness change method, the amount of liquid in the molten layer 43 is intentionally changed so that the impurity concentration C of the molten layer 43 can be increased without adding impurities during single crystal pulling.
This is a method for keeping the 1 constant and suppressing the segregation of impurities in the single crystal.
JP-A 1-250692 and JP-A-61-215285.
No. 6,009,036.

As described above, in the single crystal 46 obtained by the DLCZ method, the impurity concentration in the axial direction of the pulled single crystal 46 approaches a constant value more than that obtained by the CZ method. There is an advantage that the electrical resistivity is also made more uniform, and the yield based on the electrical resistivity is improved.

However, in any of the above-mentioned DLCZ methods, the position of the heater 42 is fixed, and the crucible 41 is set so that the raw material for the crystal can be easily melted. Therefore, it is difficult to completely control the amount of dissolution, and as a result, the impurity concentration in the molten layer 43 at the time of pulling is not completely kept constant, and the electrical resistivity in the pulled single crystal is not increased. There was a problem that it was difficult to be constant.

Further, it is not easy to control the amount of the solid layer 49 dissolved and the temperature condition of the molten layer 43 with one heater 42.

As a method for better adjusting the temperature condition of the molten layer and the amount of the solid layer dissolved, a single crystal pulling apparatus provided with a heater divided into upper and lower two stages has been proposed.

FIG. 22 is a sectional view schematically showing the single crystal pulling apparatus. The other parts except for the main heater 42a and the sub heater 42b are the same as those of the single crystal pulling apparatus shown in FIG. Only the parts will be described.

The main heater 42a is disposed concentrically outside the upper portion of the crucible 41, and a sub heater 42b having substantially the same shape as the main heater 42a is provided below the main heater 42a.
Are similarly arranged, and the main heater 42a and the sub-heater 42b are respectively connected to a power supply device capable of adjusting the power.

When a single crystal is pulled up by using the single crystal pulling apparatus constructed as described above, first, the crucible 41 is moved and fixed to a predetermined position, and the crucible 41 is pulled up by using the main heater 42a and the sub-heater 42b. All of the crystal raw materials in the above are once dissolved to form a molten layer 43. Next, the power of the sub heater 42b is turned off, and the main heater 42b is turned off.
By lowering the power of a, the lower side of the molten layer 43 is solidified to form a solid layer 49, and an impurity for doping is added to the molten layer 43 to be melted. Thereafter, while adjusting the power of the main heater 42a and the sub-heater 42b to control the dissolution amount of the solid layer 49, the single crystal is pulled up by the same method as the above-mentioned CZ method (Japanese Patent Laid-Open No. Hei 5-24972).

As described above, in an apparatus in which the main heater 42a and the sub heater 42b are provided,
The power distribution of the crucible 41 can be controlled by adjusting the power of the sub-heater 42b and the power of the sub-heater 42b separately. Can be selectively cooled to adjust the thickness of the solid layer 49.

On the other hand, there is an attempt not only to control the impurities in the single crystal but also to control the distribution of the oxygen concentration to further increase the yield. As an attempt to control the concentration of oxygen contained in a single crystal, Japanese Patent Application Laid-Open No. 62-202892 discloses a silicon single crystal pulling apparatus in which a heat insulating plate for controlling the temperature distribution of the heater is provided inside the heater. A single crystal pulling apparatus has been proposed. By controlling the environmental temperature by moving the heat insulating plate up and down, the reaction rate between the quartz crucible and the silicon melt is controlled, and the oxygen concentration is 1.35-1. It is described that a silicon single crystal in a range of 45 × 10 ¹⁸ [cm ⁻³ ] can be pulled.

[0019]

However, in an apparatus using two heaters 42a and 42b shown in FIG. 22, each time the single crystal 46 is pulled up, the main heater 42a is turned off.
a and the sub-heater 42b are consumed, the heat generation state is slightly changed. Therefore, even when the relative position of the crucible 41 with respect to the main heater 42a and the sub-heater 42b is set to be constant during the formation of the solid layer 49, Thickness changes every time. For this reason, it is difficult to form the solid layer 49 having a certain thickness, and it is difficult to control the amount of the solid layer 49 to be dissolved with good reproducibility when the formed solid layer 49 is dissolved. There were challenges.

When the solid layer 49 is formed, after the power of the sub-heater 42b is turned off, there is no means for cooling the crucible 41, so that the melt 43 cannot be cooled efficiently. , And as a result, there is a problem that the process time becomes longer and the production efficiency becomes worse.

When the molten layer 49 in the crucible 41 solidifies due to a mistake in setting the heater temperature or the like, its volume expands due to crystallization, and the crucible 41 contacts the heaters 42a and 42b due to the deformation of the crucible 41. Heaters 42a, 4
There was a problem that 2b was easily broken.

Further, regarding the control of the oxygen concentration in the single crystal, the control of the oxygen concentration in the molten layer 43 as described above is not sufficient, and it is necessary to control the temperature environment of the single crystal 46 during the single crystal pulling. There is. That is, when no heat treatment is applied to the single crystal 46 pulled during the pulling of the single crystal 46, a temperature distribution occurs in the pulling axis direction of the single crystal 46, and the obtained single crystal 46 has a different heat history depending on the portion. Will go through. The pulled single crystal 46 is cut and divided into wafers and the like and then subjected to a heat treatment to precipitate oxygen. However, due to this difference in heat history, the behavior of oxygen precipitation in the wafer is different, resulting in non-uniformity. There is a point. However, in any of the above-described methods, the heat history of such a single crystal has not been made uniform.

As a means for making the heat history uniform, a single crystal pulling apparatus in which another single heater is provided in the single crystal pulling region in order to keep the pulled single crystal 46 at a uniform temperature is disclosed (see, for example, Japanese Patent Application Laid-Open No. H11-157556). JP-A-2-48491, JP-A-57-183393, JP-A-3-33
No. 093), since the heaters different from the heaters 42a and 42b used for heating the molten layer 43 are disposed in the single crystal pulling region, the equipment cost increases and the product cost increases. There was a problem that.

The present invention has been made in view of the above problems, and the thickness and the dissolution rate of the solid layer can be arbitrarily controlled in the DLCZ method, the solid layer can be formed quickly, and the heater can be formed. It is an object of the present invention to provide a single crystal binding device that hardly causes an accident such as destruction of the single crystal, and furthermore, makes the thermal history of the single crystal uniform and can pull up a single crystal with a high yield at low cost.

[0025]

To achieve the above object, a single crystal pulling apparatus according to the present invention comprises a crucible for filling a raw material for crystallization and a main heater and a sub-heater disposed around the crucible. In a single crystal pulling apparatus configured to include a two-stage heater, at least one of the main heater and the sub-heater is provided with moving means for vertically moving the heater. (1).

According to the single crystal pulling apparatus described in the above (1), the single crystal pulling apparatus is configured to include a crucible for filling a raw material for crystallization and a two-stage heater including a main heater and a sub-heater disposed around the crucible. In single crystal pulling equipment,
Since at least one of the main heater and the sub-heater is provided with moving means for vertically moving the heater, the main heater and the sub-heater are set at appropriate positions, and After the formation of, the solid layer is quickly formed by controlling the power of the two heaters or moving the at least the sub-heater up and down using the moving means, and controlling the thickness of the solid layer and the dissolution rate thereof. Done. Also, even if the melt in the crucible solidifies, by moving the heater,
Breakage due to contact between the heater and the crucible is prevented. Further, the single crystal pulling apparatus described in the above (1) can also be used to equalize the thermal history of the single crystal.

In the apparatus for pulling a single crystal according to the above (1), the main heater and the sub-heater themselves may be made of a cylindrical material similar to a conventionally used heater, but the width of each heater is not limited. May be selected as most suitable depending on the size of the crucible, the thickness of the solid layer to be formed, and the like. Although the moving means attached to the main heater and / or the sub-heater is not particularly limited, for example, a member having a threaded hole is fixed to a part of the heater,
A threaded threaded rod is screwed into the member, and a moving means such as a device capable of moving the heater up and down by rotating the threaded rod is exemplified.

Further, the single crystal pulling apparatus according to the present invention is a single crystal comprising a crucible for filling a crystal raw material and a two-stage heater comprising a main heater and a sub-heater disposed around the crucible. The lifting device is characterized in that at least one of the main heater and the sub-heater is provided with a moving means for moving the heater in the radial direction of the crucible (2).

According to the single crystal pulling apparatus described in the above (2), the single crystal pulling apparatus is constituted to include a crucible for filling a raw material for crystallization and a two-stage heater comprising a main heater and a sub-heater disposed around the crucible. In single crystal pulling equipment,
At least one of the main heater and the sub-heater is provided with the moving means for moving the heater in the radial direction of the crucible, so that the main heater and the sub-heater are set at appropriate positions. After forming a molten layer, by controlling the power of the two heaters and moving at least the sub-heater in the radial direction of the crucible by the moving means, a solid layer is quickly formed, the thickness of the solid layer, The dissolution rate is controlled. Further, similarly to the above case, the breakage of the heater and the crucible due to solidification of the melt is prevented. Further, the single crystal pulling apparatus described in the above (2) can also be used to make the thermal history of the single crystal uniform.

In the apparatus for pulling a single crystal according to the above (2), the material of the main heater and the sub-heater may be a conventionally used material, but the cylindrical shape is such that the heater can be moved in the radial direction of the crucible. Must be divided into several parts. As the moving means, the same means as the single crystal pulling apparatus described in the above (1) can be used.

A single crystal pulling apparatus according to the present invention is a single crystal comprising a crucible for filling a raw material for crystallization and a two-stage heater comprising a main heater and a sub-heater disposed around the crucible. In the lifting device, a cooling plate is provided around the crucible, and a moving means for vertically moving the cooling plate is attached to the cooling plate (3).

According to the single crystal pulling apparatus described in the above (3), the single crystal pulling apparatus is configured to include a crucible for filling a raw material for crystallization and a two-stage heater including a main heater and a sub-heater disposed around the crucible. In the single crystal pulling apparatus, the cooling plate is provided around the crucible, and the moving means for vertically moving the cooling plate is attached to the cooling plate. After setting the sub-heater at an appropriate position to form a molten layer, by controlling the power of the two heaters and vertically moving the cooling plate, a solid layer is quickly formed, and the thickness of the solid layer and its thickness The dissolution rate is controlled. Further, the single crystal pulling apparatus described in the above (3) can also be used to equalize the thermal history of the single crystal.

[0033] In the single crystal pulling apparatus according to the above (3), the cooling plate may be a cylindrical one having a smaller radius than the sub-heater, and a moving means capable of moving up and down at a position closest to the crucible is provided. Must be attached. The cooling plate is made of a metal such as W or Mo or ceramics such as SiC, and a cooling plate in which a cooling medium is circulated so that the temperature is not increased by a heater near the cooling plate. preferable. The moving means of the cooling plate may be the same as the moving means used in the single crystal pulling apparatus according to (1).

Further, in the apparatus for pulling a single crystal according to the present invention, in the single crystal pulling apparatus according to the above (1) or (2), the cooling plate and the moving means attached to the cooling plate are provided for the crucible. It is characterized by being arranged around (4).

In the apparatus for pulling a single crystal according to the above (1) or (2), when the cooling plate and the moving means attached to the cooling plate are arranged around the crucible,
After forming the molten layer by setting the main heater and the sub-heater at appropriate positions, controlling the power of the two heaters, moving at least the sub-heater up and down by the moving means, or moving the crucible in the radial direction By moving the cooling plate up and down, the solid layer is formed more quickly, the thickness of the solid layer and the dissolution rate are more accurately controlled, and the thermal history of the single crystal is made uniform. Further, similarly to the above case, the breakage of the heater and the crucible due to solidification of the melt is prevented.

A single crystal pulling apparatus according to the present invention is a single crystal comprising a crucible for filling a crystal material and a two-stage heater comprising a main heater and a sub-heater disposed around the crucible. The lifting device is characterized in that a cooling plate is provided around the crucible, and a moving means for moving the cooling plate in a radial direction is provided on the cooling plate (5).

According to the single crystal pulling apparatus described in the above (5), the single crystal pulling apparatus is configured to include a crucible for filling a raw material for crystallization and a two-stage heater including a main heater and a sub-heater disposed around the crucible. In the single crystal pulling apparatus, the cooling plate is provided around the crucible, and the cooling plate is provided with moving means for moving the cooling plate in a radial direction. By setting a sub-heater at an appropriate position to form a molten layer, controlling the power of the two heaters, and moving the cooling plate in the radial direction of the crucible, a solid layer is quickly formed, and a solid layer is formed. The thickness and the dissolution rate are controlled. Further, the apparatus for pulling a single crystal described in the above (5) can also be used to make the thermal history of the single crystal uniform.

In the apparatus for pulling a single crystal according to the above (5), the material and configuration of the cooling plate itself may be the same as those in the apparatus for pulling a single crystal according to the above (3), and the moving means may be as described in the above (2). A moving means similar to the moving means in the case of the single crystal pulling apparatus can be used.

The single crystal pulling apparatus according to the present invention is the single crystal pulling apparatus according to the above (1) or (2), wherein the cooling plate according to (5) and the moving means attached to the cooling plate. Are arranged around the crucible (6).

In the apparatus for pulling a single crystal according to the above (1) or (2), the cooling plate according to the above (5) and the moving means attached to the cooling plate are arranged around the crucible. In the case, the main heater and the sub-heater are set at appropriate positions to form a molten layer, the power of the two heaters is controlled, and at least the sub-heater is moved up and down by the moving means or in the radial direction of the crucible. Then, by moving the cooling plate in the radial direction of the crucible, the solid layer is formed more quickly, and the thickness of the solid layer and the control of the dissolution rate are more accurately controlled. Further, similarly to the above case, the breakage of the heater and the crucible due to solidification of the melt is prevented. Further, the single crystal pulling apparatus described in the above (6) can also be used to equalize the thermal history of the single crystal.

[0041]

Embodiments and Comparative Examples Hereinafter, embodiments of a single crystal pulling apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view schematically showing a single crystal pulling apparatus according to an embodiment of the present invention. In the drawing, reference numeral 20 denotes a main chamber. The main chamber 20 is constituted by a cylindrical vacuum container 20a, and is water-cooled by a water cooling mechanism (not shown). A crucible 11 filled with a raw material for crystallization is provided at a substantially central position of the main chamber 20. The crucible 11 has a cylindrical shape with a bottom and an inner diameter of 16 inches (about 400 cm).
m), an inner layer container 11a made of quartz having a height of 14 inches (about 350 cm) and an outer layer holding container 11b made of graphite having a bottom and fitted into the outside of the inner layer container 11a. A support shaft 18 that penetrates a bottom wall of the main chamber 20 is attached to a substantially central portion of the bottom of the crucible 11, and the crucible 11 is rotatably and vertically supported by the support shaft 18.

On the upper part of the outer periphery of the crucible 11, a resistance heating type main heater 12a having a heating length of, for example, about 90 mm is provided.
resistance heating type sub-heater 12b having a heating length of about m
Are arranged concentrically, and a heat retaining cylinder 17 is provided around the outside thereof. Further, below the sub-heater 12b,
A cylindrical cooling plate 22a smaller than the diameter of the sub-heater 12b and capable of moving up and down at a position closest to the crucible 11
Are arranged. The cooling plate 22a is made of, for example, a metal such as W or Mo or ceramics such as SiC. When the cooling plate 22a is made of ceramics having particularly excellent heat resistance, the cooling plate 22a should be inserted between the sub-heater 12b and the like and the crucible 11. Thus, the heat can be sufficiently blocked, but in order to perform the cooling more efficiently, it is preferable that the structure is such that the refrigerant can flow through the inside.

The sub-heater 12b is mounted on a threaded bar 23 so as to be movable. The same moving means (not shown) is used for the main heater 12a and the cooling plate 22a.
Is attached. The means for moving the main heater 12a, the sub heater 12b, and the cooling plate 22b are described below.
Details will be described later.

On the other hand, a lifting shaft 14 is suspended above the crucible 11 so as to be rotatable and vertically movable through a small, substantially cylindrical pull chamber 21 connected to the upper part of the main chamber 20. A seed chuck 15 is provided at the lower end of the seed chuck 15.
Is mounted with a seed crystal 15a. On the other hand, a solid layer 19 is formed in the lower part of the crucible 11 and a molten layer 13 is formed in the upper part, and the lower end of the seed crystal 15a is immersed in the molten layer 13 in the crucible 11, and then rotated. The single crystal 1 from the lower end of the seed crystal 15a.
6 to grow.

The main heater 12a and the sub-heater 12b are connected to a controller (not shown) so that power can be controlled separately.

FIG. 2A is a plan view schematically showing the sub-heater 12b and a part of the moving means attached thereto in the single crystal pulling apparatus according to the embodiment.
(B) is a side view thereof. A moving member 24 is provided on one outer side of the sub-heater 12b, and a screw hole 24a is formed at the center thereof, and a screw is formed so as to have the same pitch as the screw of the screw hole 24a. A threaded rod 23 is screwed to the moving member 24. A fixing member 29 is provided on the opposite side, and a support rod 30 is fixed to the fixing member 29. An upper portion 30a of the support rod is accommodated in a cylinder 31 fixed in the furnace. The threaded rod 23 is connected to the motor 25 and the motor 2
By rotating the threaded rod 23 clockwise or counterclockwise by 5, the sub-heater 12 b is moved up and down. At this time, the upper part of the support rod 30 is slidably supported in the state of being accommodated in the cylinder 31. Therefore, the entire sub-heater 12b can be smoothly moved in the vertical direction. The material of the threaded rod 23 and the support rod 31 is preferably a metal such as W or Mo or a ceramic such as SiC.

As another embodiment, support rods 30 are provided on both sides.
The lower part of the support bar 30 of the sub-heater 12b to which the sub-heater is fixed is accommodated in a hydraulic cylinder installed outside the single crystal pulling apparatus, and the sub-heater 12b can be moved up and down by the hydraulic cylinder. Good. The upper part of the support rod 30 has the cylinder 3 as in the case of FIG.
What is necessary is just to have the structure accommodated in 1.

The main heater 12a is also provided with the same moving means, and can be moved up and down. On the other hand, the cooling plate 22a preferably has a configuration as shown in FIG. 3, for example.

FIG. 3A is a plan view schematically showing the cooling plate 22a and a part of the moving means attached thereto in the single crystal pulling apparatus according to the embodiment, and FIG.
Is a side view thereof. A support member 26 for supporting and flowing the refrigerant is disposed below the cooling plate 22a.
Is accommodated in a hydraulic cylinder (not shown). By operating this hydraulic cylinder, the cooling plate 2
2a can be moved up and down. Cooling plate 22
a and the inside of the support member 26 are hollow, and water or Ar
Cooling can be performed by flowing a cooling medium such as He or He through the support member 26 into the cooling plate 22a. However, the structure of the cavity inside the cooling plate is shown in FIG. It is preferable to have a structure divided into several rooms which are communicated by a small through hole as described above.

When a single crystal is pulled by using the single crystal pulling apparatus having the above-described structure, first, 65 kg of polycrystalline silicon is charged into the crucible 11 as a raw material for crystallization.
0.6 g of phosphorus as an n-type dopant is added therein. After setting the inside of the chamber 20 to an Ar atmosphere of about 10 Torr, the powers of the main heater 12a and the sub-heater 12b are set to about 50 kW, respectively, to about 100 kW in total, and all the crystal raw materials are once melted. Next, the power of the sub-heater 12b is turned off so that a desired solid layer thickness is obtained, the power of the main heater 12a is set to about 70 kW, the position of the main heater 12a is adjusted, and the cooling plate 22a is further moved upward.

FIG. 4 is a longitudinal sectional view schematically showing a single crystal pulling apparatus when the cooling plate 22a is moved to the vicinity of the sub-heater 12b. By moving the cooling plate 22a to the vicinity of the sub-heater 12b in this way, the radiant heat from the main heater 12a and the sub-heater 12b to the lower part of the crucible 11 can be completely shut off, and the radiant heat cooling plate 22a from the crucible 11 absorbs the heat. So that the crucible 11
The melt inside is cooled quickly, and the solid layer 13 can be grown under the melt layer 13 in a short time.

After the solid layer 19 was formed and the amount thereof was stabilized, the lower side of the seed crystal 15a was immersed in the molten layer 13, the rotation speed of the crucible 11 was set at 1 rpm, and the rotation speed of the pulling shaft 14 was set. Is set to 10 rpm and the pulling speed is set to 1.0 mm / min.
A silicon single crystal 16 having a length of 54 mm and a length of about 1000 mm is pulled up.

At this time, the single crystal is pulled up by the neck 16.
a, transition to the shoulder 16b, and to the body 16c, the power of the main heater 12a and the sub-heater 12b,
The positions of the two heaters and the position of the cooling plate 22a are readjusted, and the main heater 12a and the sub-heater 12b are pulled up while adjusting the power so that the above-mentioned pulling-up condition is maintained.

FIG. 5 shows the solid layer 19 having a thickness of 1
23 is a graph showing a comparison between the time required to form a 00 mm film and the case of using the conventional apparatus shown in FIG. 22 as a comparative example.

As is apparent from FIG. 5, it took about 8 hours to form the solid layer 19 in the conventional apparatus, while about 6 hours in the case of using the apparatus of this embodiment. 19 can be formed, the formation speed of the solid layer 19 can be increased, and the single crystal pulling time per one can be reduced.

Next, a method for controlling the thermal history of the single crystal 16 during single crystal pulling by using the single crystal pulling apparatus will be described.

In this case, as shown in FIG. 6, the main heater 12a is used as a heater for controlling the heat history of the single crystal 16 to be pulled up. In this case, after forming the solid layer 19, the main heater 12 a is moved to a position higher than the upper end of the crucible 11, and the sub-heater 12 b is moved near the center of the crucible 11 to hold the molten layer 13 on the crucible 11. Used. The conditions for pulling a single crystal are the same as those described above.

FIG. 7 shows a single crystal 16 obtained by the above method.
Is a graph showing the relationship between the distance from the top of the single crystal 16 in the axial direction and the amount of precipitated oxygen on the wafer when the wafer is cut into wafers and the same heat treatment is performed on the obtained wafer. As a comparative example, a result of similarly examining the amount of precipitated oxygen for a single crystal obtained using the conventional apparatus shown in FIG. 22 is shown.

As is clear from this figure, by controlling the thermal history when pulling the single crystal, a single crystal having a uniform amount of oxygen precipitation can be obtained at all portions.

By setting the positional relationship between the two heaters 12a and 12b and the crucible 11 as shown in FIG. 6, heat can be applied to the single crystal 16 by the main heater 12a. As a result, the single crystal 16
Can control the heat history of the crystal, can control the amount of oxygen precipitation, and can eliminate the lattice defects and lattice strains introduced in the process of pulling the single crystal by heat treatment. And a homogeneous single crystal can be obtained.

When the single crystal pulling apparatus having the above-described structure is employed, even if a large amount of the crystal raw material melt is solidified, the heaters 12a and 12b are moved so that the molten layer 13 can be solidified. It is possible to prevent the main heater 12a or the sub-heater 12b from coming into contact with the crucible 11 due to the volume expansion due to solidification, thereby preventing the crucible 11, the main heater 12a or the sub-heater 12b from being broken.

Next, another embodiment of the single crystal pulling apparatus according to the present invention will be described with reference to the drawings. FIG. 8 is a longitudinal sectional view schematically showing a single crystal pulling apparatus according to another embodiment, and FIG. 9 is a sectional view taken along line AA in FIG. In this apparatus, the main heater 12c and the sub heater 1
Except for the structure of 2d, it is substantially the same as the single crystal pulling apparatus shown in FIG. 1, and the configuration of the main heater 12c and the sub-heater 12d will be mainly described. The illustration of the heat retaining cylinder is omitted.

The main heater 12c and the sub-heater 12d according to this embodiment are both cylindrical heaters having a heating length of about 90 mm, and are arranged around the crucible 11, but move in the radial direction of the crucible 11. It is divided into eight parts as much as possible, and a moving means shown in FIG. 10 is additionally provided.

FIG. 10A is a plan view showing the sub-heater 12d and its moving means, and FIG.
FIG. 2 is a rear view as viewed from the direction in which the device 1 is provided. A sliding member 28 that slides on the rail 27 is fixed below the sub-heater 12d, and the sub-heater 12d can move on the rail 27 via the sliding member 28.
A screw hole 28a is formed substantially at the center of the sliding member 28, and the sliding member 28 is screwed to a threaded rod 23b threaded so as to have the same pitch as the screw of the screw hole 28a. . The threaded rod 23b is connected to the motor 25a, and the sub-heater 12d is moved in the radial direction of the crucible 11 by rotating the threaded rod 23b clockwise or counterclockwise by the motor 25a. . The sliding member 28 and the rail 27 are preferably disposed above and below the sub-heater 12d.
It is sufficient that b is disposed at least on either the upper or lower side. The main heater 12c is also used for the crucible 1 by the same moving means.
1 in the radial direction. The material of the rail 27 is preferably a metal such as W or Mo, or a ceramic such as SiC.

The cooling plate 22a provided in this device
Has the same configuration as the cooling plate 22a shown in FIG. 1 and can be moved up and down.

When a single crystal is pulled using the single crystal pulling apparatus having the above-described structure, the main heater 12c
In addition, except that the heating condition is changed by moving the sub-heater 12d in the radial direction of the crucible 11, substantially the same operation as that of the single crystal pulling apparatus shown in FIG. 1 may be performed.

FIG. 11 is a longitudinal sectional view schematically showing a state in which a solid layer 19 is formed below the molten layer 13 after all of the polycrystalline silicon material is dissolved. As shown, by moving the main heater 12c, the sub-heater 12d, and the cooling plate 22a, the solid layer 19 is efficiently moved.
Can be formed.

FIG. 12 shows a solid layer 19 using the above-described apparatus.
23 is a graph showing the time required to form a film having a thickness of 100 mm in comparison with the case where the conventional apparatus shown in FIG. 22 is used as a comparative example.

As is apparent from FIG. 12, it took about 8 hours to form the solid layer 49 in the conventional device, whereas in the case of using the device of the present embodiment, the solid layer 19 was formed in about 6 hours. Can be formed, the formation speed of the solid layer 19 can be increased, and the single crystal pulling time per one can be shortened.

FIG. 13 shows two heaters 12c and 1c for controlling the thermal history of the single crystal when pulling the single crystal.
It is a longitudinal cross-sectional view which shows typically the state of the single crystal pulling apparatus when the position of 2d is adjusted. By thus arranging the main heater 12c and the sub-heater 12d a little away from the crucible 11, the heating area of the heaters 12c and 12d can be expanded, and the single crystal 16 can be heat-treated under appropriate temperature conditions. FIG. 14 shows a single crystal 16 obtained by cutting the single crystal 16 obtained by controlling the thermal history of the single crystal 16 as shown in FIG. 13 and dividing it into wafers, and subjecting the obtained wafer to the same heat treatment. 4 is a graph showing a relationship between a distance from a top of a crystal 16 in an axial direction and an amount of precipitated oxygen on a wafer. As a comparative example, a result of similarly examining the amount of precipitated oxygen for a single crystal obtained using the conventional apparatus shown in FIG. 22 is shown.

As is clear from FIG. 14, by controlling the thermal history at the time of pulling a single crystal, a single crystal having a uniform amount of precipitated oxygen can be pulled at all portions.

Next, still another embodiment of the single crystal pulling apparatus according to the present invention will be described with reference to the drawings. FIG. 15 is a longitudinal sectional view schematically showing a single crystal pulling apparatus according to still another embodiment, and FIG. 16 is a sectional view taken along line BB in FIG.
It is a line sectional view.

This apparatus is substantially the same as the single crystal pulling apparatus shown in FIG. 8 except for the structure of the cooling plate 22b and the combination of the cooling plate 22b and the heaters 12c and 12d. And the combination of the cooling plate 22b and the heaters 12c and 12d will be described.

The cooling plate 22b provided in this apparatus has a cylindrical shape and is disposed around the crucible 11;
Are divided into eight portions so as to be movable in the radial direction. The material of the cooling plate 22b is the cooling plate 22a shown in FIG.
The material may be the same as that described above, and it is desirable that the refrigerant is made to flow through the inside of the cavity. Moving means is attached to the cooling plate 22b similarly to the configuration of the main heater 12c and the sub-heater 12d shown in FIG. 10, and the cooling plate 22b mounted on the rail 27 via the sliding member 28 is screwed. It is configured to move by rotating the stick 23b. FIG.
FIG. 6 shows a case where the rail 27 is provided only below the cooling plate 22b, but the rail 27 may be provided above and below the cooling plate 22b.

As shown in FIG. 16, the sub-heater 12
Since d and the cooling plate 22b move in the radial direction of the crucible 11 at the same height, it is necessary to prevent them from contacting each other when moving. That is, when the cooling plate 22b is moved near the periphery of the crucible 11 by moving the sub-heater 12d away from the crucible 11, the sub-heater 12d is
What is necessary is to move the cooling plate 22b to a position near the periphery of the crucible 11 after moving the cooling plate 22b to a position sufficiently far from the crucible 11 so that the 2b does not come in contact with the moving plate 2b.

When a single crystal is pulled by using the single crystal pulling apparatus constructed as described above, the main heater 12c
In addition, except that the heating condition is changed by moving the sub-heater 12d in the radial direction of the crucible 11, substantially the same operation as in the case of the single crystal pulling apparatus shown in FIG. 1 may be performed.

First, the polycrystalline silicon material is charged into the crucible 11 and all the polycrystalline silicon material is melted using the main heater 12c and the sub-heater 12d. Then, the power of the sub-heater 12d is turned off, and the sub-heater 12d is turned off.
Is moved away from the periphery of the crucible 11, then the cooling plate 22 b is moved around the crucible 11 to cool the lower part of the crucible 11, and the solid layer 19 is formed below the molten layer 13.
As described above, by moving the main heater 12c, the sub-heater 12d, and the cooling plate 22, the solid layer 19 can be efficiently formed.

FIG. 17 shows the solid layer 19 using the above-described apparatus.
23 is a graph showing a comparison between the time required to form a film having a thickness of 100 mm and the conventional apparatus shown in FIG. 22 as a comparative example.

As is apparent from FIG. 17, it took about 8 hours to form the solid layer 49 in the conventional apparatus, whereas in the case of using the apparatus of this embodiment, it took about 6 hours. 19 can be formed, the formation speed of the solid layer 19 can be increased, and the single crystal pulling time per one can be reduced.

FIG. 18 shows two heaters 12c and 1c for controlling the thermal history of the single crystal when pulling the single crystal.
It is the longitudinal cross-sectional view which showed typically the state of the single crystal pulling apparatus at the time of adjusting the position of 2d. By thus arranging the main heater 12c and the sub-heater 12d slightly away from the crucible 11, the heating region of the heaters 12c and 12d can be expanded, and the pulled single crystal 16 can be heat-treated under appropriate conditions.

FIG. 19 shows a case where the single crystal 16 obtained by controlling the thermal history of the single crystal 16 as shown in FIG. 18 is cut into wafers, and the obtained wafer is subjected to the same heat treatment. 5 is a graph showing the relationship between the distance of the single crystal 16 from the top in the axial direction and the amount of oxygen precipitated on the wafer. As a comparative example, a result of similarly examining the amount of precipitated oxygen for a single crystal obtained using the conventional apparatus shown in FIG. 22 is shown.

As is clear from FIG. 19, by controlling the thermal history at the time of pulling a single crystal, a single crystal having a uniform oxygen precipitation amount at all portions can be pulled.

[0083]

As described above in detail, the single crystal pulling apparatus according to the above (1) comprises a crucible for filling a raw material for crystallization and a main heater and a sub-heater disposed around the crucible. In a single crystal pulling apparatus configured to include a two-stage heater, at least one of the main heater and the sub-heater is provided with a moving unit that allows the heater to move in a vertical direction. After setting the main heater and the sub-heater at appropriate positions to form a molten layer, by controlling the power of the two heaters and moving at least the sub-heater up and down using the moving means, the solid layer is formed. It can be formed quickly, and the thickness of the solid layer and the dissolution rate thereof can be controlled. Further, even if the molten liquid in the crucible solidifies, the heater or the crucible can be prevented from being broken due to the contact between the heater and the crucible by moving the heater. Further, the single crystal pulling apparatus described in the above (1) can be used to make the thermal history of the single crystal uniform.

Further, the single crystal pulling apparatus according to the above (2) includes a crucible for filling the raw material for crystallization and a two-stage heater comprising a main heater and a sub-heater disposed around the crucible. In the single crystal pulling device, the moving means for moving the heater in the radial direction of the crucible is added to at least one of the main heater and the sub-heater,
After forming the molten layer by setting the main heater and the sub-heater at appropriate positions, by controlling the power of the two heaters and moving at least the sub-heater in the radial direction of the crucible by the moving means, the solid The layer can be formed quickly and the thickness of the solid layer and its dissolution rate can be controlled. Further, similarly to the case described above, it is possible to prevent the heater and the crucible from being broken due to solidification of the melt. Further, the single crystal pulling apparatus described in the above (2) can be used to make the thermal history of the single crystal uniform.

Further, the single crystal pulling apparatus according to the above (3) comprises a two-stage heater comprising a crucible for filling a crystal raw material and a main heater and a sub-heater disposed around the crucible. In the single crystal pulling apparatus, the cooling plate is provided around the crucible, and the moving means for vertically moving the cooling plate is added to the cooling plate. And after setting the sub-heater at an appropriate position to form a molten layer,
By controlling the power of the two heaters and moving the cooling plate vertically, a solid layer can be quickly formed,
The thickness of the solid layer and its dissolution rate can be controlled.
Further, the single crystal pulling apparatus according to the above (3) can be used to make the thermal history of the single crystal uniform.

In the single crystal pulling apparatus according to (1) or (2), when the cooling plate and the moving means described in (3) are provided around the crucible, the main heater and the sub-heater are used. After setting the molten layer at an appropriate position, controlling the power of the two heaters, moving at least the sub-heater up and down by the moving means, or moving the crucible in the radial direction, and moving the cooling plate up and down By moving, the solid layer can be quickly formed, and the thickness of the solid layer and the dissolution rate thereof can be controlled. Further, similarly to the case described above, it is possible to prevent the heater and the crucible from being broken due to solidification of the melt. The single crystal pulling apparatus can be used to equalize the thermal history of the single crystal.

Further, in the single crystal pulling apparatus according to the above (5) according to the present invention, a two-stage crucible filled with a crystal raw material and a main heater and a sub-heater disposed around the crucible are provided. In the single crystal pulling apparatus including a heater, the cooling plate is provided around the crucible, and the cooling plate is provided with moving means for moving the cooling plate in a radial direction. By setting the main heater and the sub-heater at appropriate positions to form a molten layer, controlling the power of the two heaters, and moving the cooling plate in the radial direction of the crucible, the solid layer can be quickly formed. The thickness of the solid layer and the dissolution rate thereof can be controlled. Further, the single crystal pulling apparatus described in the above (5) can be used to make the thermal history of the single crystal uniform.

Further, in the single crystal pulling apparatus according to the above (1) or (2), wherein the cooling plate and the moving means according to the above (5) are arranged around the crucible, The heater and the sub-heater are set at appropriate positions to form a molten layer, the power of the two heaters is controlled, and at least the sub-heater is moved vertically by the moving means, or in the radial direction of the crucible, Is moved in the radial direction of the crucible, whereby a solid layer can be quickly formed, and the thickness of the solid layer and the dissolution rate thereof can be controlled. Further, similarly to the case described above, it is possible to prevent the heater and the crucible from being broken due to solidification of the melt. Also, the single crystal pulling apparatus,
It can be used to equalize the thermal history of a single crystal.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a single crystal pulling apparatus according to an embodiment of the present invention.

FIG. 2A is a plan view schematically showing a sub-heater and a part of a moving unit attached to the sub-heater in the single crystal pulling apparatus according to the embodiment, and FIG. FIG.

FIG. 3A is a plan view schematically showing a cooling plate and a part of a moving means attached to the cooling plate in the single crystal pulling apparatus according to the embodiment, and FIG. It is the front view.

FIG. 4 is a longitudinal sectional view schematically showing a state of the single crystal pulling apparatus when the cooling plate is moved to the vicinity of a sub-heater in the single crystal pulling apparatus according to the embodiment.

FIG. 5 is a graph showing a time distribution required for forming a solid layer having a thickness of 100 mm below a melt in a crucible in Examples and Comparative Examples.

FIG. 6 is a longitudinal sectional view schematically showing a state of the single crystal pulling apparatus when a main heater is used as a heater for controlling the thermal history of the single crystal to be pulled in the single crystal pulling apparatus according to the embodiment. is there.

FIG. 7 shows a case where a wafer is manufactured using the single crystal obtained in the example (when a main heater is used as a heater for controlling the thermal history of a single crystal to be pulled) and in the comparative example, and the wafer is subjected to heat treatment. 4 is a graph showing the relationship between the distance from the top of the single crystal in the axial direction and the amount of precipitated oxygen when the single crystal is formed.

FIG. 8 is a longitudinal sectional view schematically showing a single crystal pulling apparatus according to another embodiment.

9 is a cross-sectional view of the single crystal pulling apparatus according to another embodiment, taken along line AA in FIG.

FIG. 10A is a plan view showing a sub-heater 12d and its moving means, and FIG. 10B is a rear view thereof.

FIG. 11 is a longitudinal sectional view schematically showing a state of a single crystal pulling apparatus when a solid layer is formed below a molten layer in a single crystal pulling apparatus according to another embodiment.

FIG. 12 is a graph showing the distribution of time required when repeating an experiment in which a solid layer was formed to a thickness of 100 mm below a melt in a crucible in another example and a comparative example.

FIG. 13 is a longitudinal sectional view schematically showing a state of a single crystal pulling apparatus when used as a heater for controlling the thermal history of a single crystal for pulling a main heater and a sub heater.

FIG. 14 shows another example (in which the main heater and the sub-heater are used as a heater for controlling the thermal history of a single crystal for pulling up the main heater and the sub-heater) and a single crystal obtained in the comparative example. 4 is a graph showing the relationship between the distance from the top of the single crystal in the axial direction and the amount of precipitated oxygen when heat treatment is performed on the single crystal.

FIG. 15 is a longitudinal sectional view schematically showing a single crystal pulling apparatus according to still another embodiment.

FIG. 16 is a sectional view taken along line BB of FIG. 15 of a single crystal pulling apparatus according to still another embodiment.

FIG. 17 is a graph showing a time distribution required for forming a solid layer having a thickness of 100 mm below a melt in a crucible in still another example and a comparative example.

FIG. 18 is a longitudinal sectional view schematically showing a state of a single crystal pulling apparatus when used as a heater for controlling the thermal history of a single crystal for pulling a main heater and a sub heater in still another embodiment. .

FIG. 19 shows a wafer manufactured using a single crystal obtained in another example (when the main heater and the sub-heater are pulled up and used as a heater for controlling the thermal history of the single crystal) and a single crystal obtained in a comparative example. 4 is a graph showing the relationship between the distance from the axial top of a single crystal and the amount of precipitated oxygen when a wafer is subjected to heat treatment.

FIG. 20 is a cross-sectional view schematically showing a single crystal pulling apparatus using a conventional CZ method.

FIG. 21 is a cross-sectional view schematically showing a single crystal pulling apparatus using a conventional DLCZ method.

FIG. 22 is a cross-sectional view schematically showing a single crystal pulling apparatus using two heaters in a conventional DLCZ method.

[Explanation of symbols]

 11 crucible 12a, 12c main heater 12b, 12d sub-heater 22a, 22b cooling plate 23, 23a threaded rod 25 motor 27 rail

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Takayuki Kubo 4-33, Kitahama, Chuo-ku, Osaka-shi, Osaka Prefecture Sumitomo Metal Industries, Ltd. (72) Hideki Fujiwara 4-chome, Kitahama, Chuo-ku, Osaka-shi, Osaka No. 5-33 Sumitomo Metal Industries, Ltd. (72) Inventor Shuichi Inami 4-33 Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries, Ltd.

Claims (6)

[Claims] 1. A single crystal pulling apparatus comprising a crucible for filling a crystal raw material and a two-stage heater comprising a main heater and a sub-heater disposed around the crucible, wherein the main heater and the sub-heater are provided. Wherein at least one of the heaters is provided with moving means for vertically moving the heater. 2. A single crystal pulling apparatus comprising a crucible for filling a crystal raw material and a two-stage heater comprising a main heater and a sub-heater disposed around the crucible, wherein the main heater and the sub-heater are provided. A moving means for moving the heater in a radial direction of the crucible is attached to at least one of the heaters. 3. A single crystal pulling apparatus including a crucible for filling a raw material for crystallization and a two-stage heater comprising a main heater and a sub-heater disposed around the crucible, wherein cooling around the crucible is performed. A single crystal pulling apparatus, wherein a plate is provided, and a moving means for vertically moving the cooling plate is attached to the cooling plate. 4. The single crystal pulling apparatus according to claim 1, wherein the cooling plate and the moving means attached to the cooling plate are arranged around the crucible. 5. A single crystal pulling apparatus including a crucible for filling a raw material for crystallization and a two-stage heater comprising a main heater and a sub-heater disposed around the crucible, wherein cooling around the crucible is performed. A single crystal pulling apparatus, wherein a plate is provided, and moving means for moving the cooling plate in a radial direction is provided on the cooling plate. 6. The single crystal according to claim 1, wherein the cooling plate according to claim 5 and the moving means attached to the cooling plate are disposed around a crucible. Lifting device.