JP2000327479A - Single crystal production apparatus and single crystal production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single crystal production apparatus for production a high-quality single crystal which reduces the defect sizes of the defects (grown-in defects) generated in a temperature region of 1,150 to 1,080 deg.C passing at the time of pulling up of the single crystal by increasing the product of a pulling up speed and the temperature gradient in the defect forming temperature region described above and improves the yield of the device by decreasing the grown-in defect density after the heat treatment of a wafer and a process for producing the single crystal. SOLUTION: A radiation screen 40 of the single crystal production apparatus 20 having a crucible 26 which holds a melt 30 which is a single crystal material, a heater 28 which exists at the circumference of the crucible and heats the melt, a vertically movable supporting means 32 which exists above the melt in the crucible and the radiation screen 40 which is connected to the supporting means and encloses the single crystal 36 growing in the lower part of a seed crystal 34 is formed to an annular shape which is nearly a hollow triangular shape in its cross-sectional shape and encloses the single crystal. Thermally insulating materials of a prescribed thickness are installed to the inner side of a heat shielding plate disposed in such a manner that the inside surface side facing the single crystal gradually tapers to an inverted frustoconical shape, by which the spaces to decrease the radiation heat between the thermally insulating materials are disposed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a single crystal manufacturing apparatus and a single crystal manufacturing method, and more particularly, to a single crystal manufacturing apparatus using a CZ method (Czochralski method) and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, as a single crystal manufacturing apparatus for pulling a single crystal using the CZ method, as a conventional example 1, as shown in FIG. A configuration in which the screen 3 is disposed has been proposed (Japanese Patent Publication No. 57-40119). In this single crystal manufacturing apparatus, the radiant heat from the crucible 4, the heater 5, and the melt surface 6 is cut off by the radiation screen 3 arranged so as to surround the single crystal 1, thereby increasing the axial temperature gradient of the single crystal. It has become. Also, chamber 7
By guiding an inert gas such as Ar supplied from above into the crucible 4, SiO gas or the like generated from the surface of the silicon melt is smoothly discharged from the crucible 4 to the outside of the chamber 7.

However, in the single crystal manufacturing apparatus shown in FIG. 11, the reflected heat emitted from the melt surface 6 toward the single crystal 1 and the radiant heat from the heater 5 and the crucible 4 are sufficiently shut off. Can not do. As a result, the cooling effect on the single crystal 1 is insufficient, so that the time required to pass through a temperature range of 550 to 850 ° C., which is liable to cause oxygen-induced stacking faults, becomes longer, and the crystal quality may be degraded.

A single crystal manufacturing apparatus disclosed in Japanese Patent No. 2562245 has been made to solve this problem. In the following, the same reference numerals are given to the same components as described above, and description thereof will be omitted. In the single crystal manufacturing apparatus of the second conventional example, as shown in FIG. 12, a second screen 3b is provided inside the first screen 3a so as to open around the single crystal pulling region and have a parabolic inner cross section. It has become something. Due to the parabolic shape of the second screen 3b, absorptive radiant heat and radiant heat from near the solid-liquid interface 6 can be reflected upward by the effect of the solid angle. It is described that the axial temperature gradient above the solid-liquid interface 6 can be increased, so that the oxygen-induced stacking faults can be improved and the pulling speed of the single crystal 1 can be increased.

Further, in the single crystal manufacturing apparatus disclosed in Japanese Patent Publication No. Hei 5-35715 of Conventional Example 3, as shown in FIG. 13, the single crystal manufacturing apparatus is supported by a support plate 7 and faces a single crystal pulling region. The inner surface side of the screen 3 to be formed is formed in an inverted frustoconical ring whose diameter is reduced from the upper end side toward the lower end side, and a part or the whole is formed between the inner surface side and the outer surface side toward the melt surface side. Insulation material 9 with increased thickness over
, And a structure using felt having excellent heat insulation inside. As a result, the radiant heat from the heater 5, the crucible 4, the melt 8, and the like is cut off, an appropriate temperature gradient is formed in the single crystal 1 in the pulling direction, and the pulling speed of the single crystal 1 is increased. In addition, it is described that stacking fault density can be reduced and manufacturing efficiency can be improved by passing through a temperature range of 550 to 850 ° C., which is considered to cause stacking faults, in a short time.

[0006]

However, the conventional single crystal manufacturing apparatus has the following problems. The crystal defects generated in the single crystal include the aforementioned 550 to 85
Apart from oxygen-induced stacking faults occurring in the temperature range of 0 ° C., there is a defect (Grown-in defect) formed in the temperature range of 1150 to 1080 ° C., which passes when pulling a single crystal.
The defect size of the grown-in defect is a product (cooling rate) of a pulling speed and a temperature gradient in the defect formation temperature region.
Has already been clarified from the results of experiments. However, in the single crystal manufacturing apparatus disclosed in Japanese Patent Publication No. 2562245, a heater and a heat absorber are provided on the crucible wall side, and the heat absorber is in contact with the heat insulator, so that the temperature of the heat insulator increases. Then, the heat of the raised heat insulating material is radiated and transmitted to the second screen facing the single crystal. In addition, since the second screen is formed only of the plate, the temperature rises due to radiant heat from the heat insulating material and the surface of the melt, and the temperature gradient of the defect forming region which affects the defect size of the grown-in defect can be made too large. Did not. Therefore, the effect of increasing the pulling speed only contributes to the reduction of the size of the grown-in defect.

In the single crystal manufacturing apparatus disclosed in Japanese Patent Publication No. Hei 5-35715, the inside of the heat shield plate is filled with a heat insulating material having an increased thickness over a part or all of a triangular cross section. Therefore, the heat of the heat shield plate facing the heater, crucible and the melt is transmitted as heat conduction to the heat shield plate facing the single crystal via the heat insulating material, and is added to the heat shield plate facing the single crystal. As a result, heat transfer due to heat radiation increases and cooling efficiency decreases. For this reason, the magnitude of the temperature gradient in the defect formation region is insufficient, and the size of the grown-in defect cannot be sufficiently reduced.

The present invention is directed to a single crystal manufacturing apparatus and a single crystal manufacturing method, focusing on the above-described conventional problems. In particular, the present invention relates to a defect (Grown) formed in a temperature range of 1150 to 1080.degree. -In defect) is reduced by increasing the product (cooling rate) of the pulling rate and the temperature gradient in the defect formation temperature region, thereby effectively eliminating the grown-in defect size after the wafer heat treatment. Accordingly, an object of the present invention is to provide a single crystal manufacturing apparatus and a single crystal manufacturing method for improving the yield of devices and manufacturing high quality single crystals.

[0009]

In order to achieve the above object, in the invention of a single crystal manufacturing apparatus according to the present invention, there is provided a crucible for holding a melt as a single crystal material, and a crucible around the crucible. A single crystal manufacturing apparatus comprising: a heater for heating a liquid crystal; a vertically movable support means positioned above the melt in the crucible; and a radiation screen surrounding the single crystal growing below the seed crystal connected to the support means. The radiation screen is formed in a ring shape surrounding the single crystal with a substantially triangular hollow cross section, and the inner surface facing the single crystal is gradually reduced to an inverted truncated cone shape. A heat insulating material having a predetermined thickness is provided on the inside, and a space for reducing radiant heat between the heat insulating materials is provided.
Further, it is preferable to provide a gap for blocking conduction heat on the end surface of the adjacent heat insulating material.

In the invention of the method for producing a single crystal according to the present invention, the single crystal material is heated and melted to form a melt, and the seed crystal is immersed in the melt and pulled up to produce a single crystal. In the defect formation temperature region of 1150 to 1080 ° C. through which the single crystal passes when pulled, the inside surface facing the single crystal has an inverted truncated cone shape, and the inside of the heat shield plate has a hollow triangular cross section. A radiation screen having a space between the attached heat insulating materials is provided as a space for increasing the temperature gradient in the defect formation temperature region, and the single crystal is pulled up at a high pulling speed by using the radiation screen to reduce the temperature gradient. Growing the product (cooling rate) with the upper speed, Gro
After reducing the defect size of the wn-in defect to a minute size to produce a single crystal rod, and cutting the wafer from the single crystal rod,
In this manufacturing method, the wafer is heat-treated in a non-oxidizing atmosphere containing a hydrogen gas, an argon gas, or the like so that the inside of the wafer is defect-free.

[0011]

In the CZ method, the temperature of the single crystal surrounded by the radiation screen is substantially determined by heat conduction from the melt, radiation from the melt surface, and radiation from the heat shield plate. Assuming that there is no difference between the amount of heat conduction from the melt and the amount of radiation from the surface of the melt between the prior arts, the temperature of the single crystal surface is determined by the heat transfer between the surface of the heat shield plate and the surface of the single crystal. It is almost determined by the exchange of quantity. For this reason, the temperature gradient on the surface of the single crystal can be increased by minimizing the amount of heat on the surface of the heat shield plate for exchanging heat transfer with the single crystal.

According to the above configuration of the present invention, as shown in FIG. 7 (the reference numerals in FIG. 7 are the same as those in FIG. 1 described later), the radiation screen 40 is provided with the heat insulating material 44 inside the heat shielding plate 42. And a space Ma on the inner surface surrounded by the heat insulating material 44.
Therefore, the amount of heat received by the oblique side 40a of the heat shielding plate 42 facing the single crystal surface depends on the amount of heat transferred by the heat conducting through the heat shielding plate 42 itself and the amount of heat transferred by the heat insulating material 44 itself. It is determined by adding the amount of heat transfer and the amount of heat transfer between the heat insulating materials 44 due to heat radiation. In the present invention, a heat insulating material 44 having a predetermined thickness is disposed inside the heat shielding plate 42, and the heat insulating material 44 prevents heat transfer due to heat radiation propagating through the space Ma provided between the heat shielding plates 42. The heat shielding plate 42 can be sufficiently shielded, and the amount of heat received by the oblique side 40a of the heat shielding plate 42 can be reduced. In other words, the heat radiated by the object into the space increases sharply as the temperature of the object increases,
In the present invention, the surface of the heat insulating material 44 that radiates heat reduces heat due to heat conduction from the heat shield plate 42 by the heat insulating material 44, and the reduced heat of the surface of the heat insulating material 44 is radiated to the space Ma.
Since the heat is transmitted to the surface of the heat insulating material 44, heat transfer due to heat radiation is substantially blocked.
The amount of heat received by a can be reduced.

The amount of heat received by the oblique side 40a of the heat shield plate 42 decreases in proportion to the distance from the melt and increases as the distance from the melt increases, and the temperature of the opposed single crystal also decreases. The amount of heat transfer between the single crystal surface and the oblique side 40a of the heat shield plate 42 decreases as going upward. Therefore, as shown by the solid line (A) in FIG. 10, the amount of heat of the oblique side 40a of the heat shielding plate 42 decreases in proportion to the distance from the melt. As described above, in the present invention, the amount of heat received by the oblique side 40a of the heat shield plate 42 is small, and the amount of heat transmitted from the heat shield plate 42 to the single crystal surface decreases as going upward, so that the single crystal temperature region G2 (1150 ° C ~
1080 ° C.). Thereby, the temperature gradient of the single crystal facing the oblique side 40a of the heat shielding plate 42 can be increased, and the pulling speed of the single crystal can be increased accordingly. The defect size of the defect can be made small so that it can be effectively eliminated easily during the wafer heat treatment.

In FIG. 7, the radiation screen is
A heat insulating material 44 is provided inside the heat shielding plate 42 and a gap is provided between the end surfaces of the heat insulating material 44, so that heat conduction can be cut off. Hypotenuse 40 of the heat shield plate 42
The amount of heat received by a can be reduced. As a result, the heat shielding plate 4
The oblique side 40a of No. 2 has a large temperature gradient in the axial direction of the heat shield plate as shown by the solid line (A) in FIG.
The temperature region G2 of the opposing single crystal (1150 ° C. to 1080
C) can be further increased. In addition,
In FIG. 10, the horizontal axis represents the distance Ln (shown in FIG. 2) from the melt to the heat shield, and the vertical axis represents the amount of heat received by the oblique side of the heat shield. At this time, the back surface and the front surface of the heat shield plate have substantially the same temperature.

On the other hand, the conventional Japanese Patent Publication No. 5-3571
In the radiation screen 3 as shown in FIG. 8 of Japanese Patent Publication No. 5 (the same reference numeral is used as in FIG. 13), the amount of heat received by the heat shielding plate 3a facing the single crystal surface is as described above. The amount of heat transferred by the heat conduction transmitted through the shield plate 3a itself, and the heat shield plate 3a through the heat insulating material 9 from the heat shield plates other than the heat shield plate 3a.
It is determined by adding the amount of heat transfer due to the heat conduction to a. The amount of heat received by the surface of the heat shielding plate 3a is smaller than the amount of heat transferred from the surface of the heat insulating material 44 of the present invention through the space to the opposing surface of the heat insulating material 44. 9 through the heat insulating material 9 and the heat shielding plate 3a.
The amount of heat transfer due to heat conduction transmitted to is larger. Therefore, the amount of heat received by the surface of the heat shield plate 3a facing the single crystal surface is equal to the space M from the surface of the heat insulating material 44 of the present invention.
a is larger than that which is thermally conducted to the oblique side 40a of the heat shielding plate 42 after propagating a. The amount of heat received on the surface of the heat shielding plate 3a decreases in proportion to the distance from the melt, and the amount of heat transfer of the heat shielding plate 3a decreases as going upward.
As described above, since the heat transfer amount of “a” is larger than that of the present invention, the decrease amount of the heat amount of the heat shielding plate 3a is reduced.
Therefore, as shown by the dotted line (B) in FIG. 10, the heat quantity of the heat shielding plate 3a decreases in proportion to the distance from the melt, but is larger than that of the present invention. As described above, in this conventional technique, since the amount of heat received by the heat shield plate 3a is larger than that of the present invention, the amount of heat that propagates from the heat shield plate 3a to the single crystal surface also increases, and the temperature region G2 (1150) of the single crystal.
C. to 1080 C.) is smaller than in the present invention.

The heat shielding plate 42 of the radiation screen has the same shape as that of FIG. 7 and a heat insulating material 44 is provided inside as shown in FIG.
Is not provided, and has a space M, the amount of heat received by the oblique side 40a of the heat shield plate 42 facing the single crystal surface is the amount of heat transfer by heat conduction transmitted through the heat shield plate 42 itself, and It is determined by adding the heat transfer amount due to the heat radiation propagating in the space M between the heat shielding plates 42. As described above, the heat radiated from the object to the space rapidly increases as the temperature of the object increases, so that the heat insulating material 44 is provided between the heat shielding plates 42.
In the case of FIG. 9 in which the heat is not blocked by the heat shield plate 42, high heat is directly radiated from the heat shield plate 42 to the space M and propagated. As shown by the three-dot chain line (C), the amount of heat becomes extremely large, and the amount of heat received by the hypotenuse 40a of the heat shield plate 42 facing the single crystal surface becomes extremely large. Further, the amount of heat transferred by heat conduction through the heat shield plate 42 itself, which is the same as the present invention, is added to the heat amount of the three-dot chain line (C), and the amount of heat received by the oblique side 40a of the heat shield plate 42 is represented by the two-dot chain line (D). ). As a result of an increase in the amount of heat received by the oblique side 40a of the heat shielding plate 42, the amount of heat of the heat shielding plate 42 decreases in proportion to the distance from the melt as shown by the two-dot chain line (D) in FIG. It is even larger than the prior art. Thus, in this prior art, the heat shielding plate 4
2, the amount of heat transmitted from the heat shield plate 3a to the single crystal surface is further increased, and the temperature gradient of the single crystal temperature region G2 (1150 ° C. to 1080 ° C.) is smaller than that of the present invention. ing.

Further, the method for producing a single crystal according to the present invention comprises:
Radiation having a space between heat insulators provided inside a heat shield plate having an inverted truncated conical shape on the inner surface side facing the single crystal and a hollow triangular cross section in a defect formation temperature region of 1150 to 1080 ° C. In order to provide a space with a large temperature gradient surrounded by a screen and to pull a single crystal from the melt at a predetermined cooling rate or more using the radiation screen,
The defect size of the row-in defect can be reduced. After the single crystal is cut into wafers, the wafers are heat-treated in a non-oxidizing atmosphere containing hydrogen gas, so that the defects can be effectively eliminated by hydrogen heat treatment, and the defect-free area extends to the inside of the wafer. And a good oxide film breakdown voltage non-defective product ratio (GOI) can be secured.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a single crystal manufacturing apparatus and a single crystal manufacturing method according to the present invention will be described below in detail with reference to the accompanying drawings. The same parts as those in the related art are denoted by the same reference numerals, and description thereof will be omitted. FIG. 1 is an overall conceptual side view of a single crystal manufacturing apparatus 20 according to the first embodiment of the present invention. FIG. 2 is a partially enlarged side view of the first embodiment of the single crystal manufacturing apparatus 20, and FIG. 3 is a partially enlarged view of a radiation screen portion. In this embodiment, a CZ method (Czochralski method) is used in which a polycrystal is melted in a crucible to form a melt, and a seed crystal is immersed in the melt and pulled up to grow a single crystal to a predetermined size. The case where a single crystal is manufactured by the method will be described.

In FIG. 1, the chamber 22 of the single crystal manufacturing apparatus 20 has a configuration in which a cylindrical top chamber 24 is incorporated in the upper part. A crucible 26 for holding a melt 30 of a single crystal material is rotatably and vertically movable inside the chamber 22. The crucible 26 has a shape in which the melt 30 side is formed of a quartz crucible 26a and the quartz crucible 26a is covered with a graphite crucible 26b. A heater 28 for heating and melting the melt 30 is disposed around the crucible 26, and a heat insulating wall 29 is disposed concentrically around the heater 28.

In the crucible 26, the melt 30 obtained by heating and melting the polycrystal as described above is held. A seed crystal 34 is connected to the support means 32 which is arranged above the center axis of the top chamber 24 and which can move up and down.
Is dipped in the melt 30 and pulled up to obtain a rod-shaped single crystal 3.
6 can be manufactured. In the vicinity of the upper side of the upper surface 30a of the melt 30, a radiation screen 40 is formed, which surrounds the single crystal 36 and has a substantially triangular annular cross section and is formed in a ring shape.

The radiation screen 40 is connected to supporting screens 60 and 62 fixed to the chamber 22. From above the top chamber 24, an inert gas 64 is caused to flow in the axial direction of the single crystal 36, and between the seed crystal 34 and the oblique side 40a of the radiation screen 40, the upper surface 30a of the melt 30 and the bottom 40b of the radiation screen 40. , And between the side 40c of the radiation screen 40 and the inner wall 26c of the crucible 26, and flows downward from the outer periphery of the crucible 26.

In FIG. 2, the radiation screen 40 is formed in a substantially right-angled triangular shape, and has a heat shield plate 42 having a predetermined thickness comprising an oblique side 40a, a bottom side 40b, and a side side 40c. And a heat insulating material 44 of a predetermined thickness attached to each side of the above. The oblique side heat shield plate 42a of the oblique side 40a of the radiation screen 40 is a single crystal 3
The oblique side 40a on the inner surface side facing 6 has an inverted truncated cone shape, and is formed so as to gradually decrease toward the single crystal 36 toward the melt 30 side. Further, the bottom side heat shield plate 42b of the bottom side 40b is located near the melt 30 and
It is formed substantially parallel to the upper surface 30a of the melt 30 at a predetermined interval. Side heat shield plate 42 of side 40c
“c” is disposed substantially parallel to the inner wall 26c of the crucible 26 at predetermined intervals.

The heat insulating material 44 includes a heat insulating material 44a for the hypotenuse attached to the heat shielding plate 42a for the oblique side and a heat insulating plate 42b for the bottom side.
And a side heat insulating material 44c attached to the side heat shield plate 42c.

In this embodiment, the heat shield plate 42 has a predetermined thickness, for example, a thickness of about 5 mm in this embodiment, and is made of high-density graphite having high heat resistance. I have. The heat insulating material 44 has a predetermined thickness, for example,
In this embodiment, graphite felt having a thickness of about 20 mm and having low thermal conductivity is used as a material. Insulation material 4
Both end surfaces of the oblique side heat insulating material 44a and the bottom side heat insulating material 44b are in contact with the adjacent heat insulating materials 44. The heat insulating material 44c for the side is a heat insulating material 44 for the oblique side in the middle part.
a, and one end surface of the side heat insulating material 44c is in contact with an end surface of the bottom heat insulating material 44b. Inside the radiation screen 40, there is a space Ma having a predetermined area or more surrounded by the inner surfaces of the heat insulating material 44a for the oblique side, the heat insulating material 44b for the bottom side, and the heat insulating material 44c for the side side.

FIG. 3 shows the radiation screen 4 of the first embodiment.
FIG. 2 is a partially enlarged view of a modification example of FIG. 0. In FIG. 2 described above, the heat insulating material 44a for the oblique side and the heat insulating material 44b for the bottom side of the heat insulating material 44 are shown.
Each end face of each is brought into contact with the adjacent heat insulating material 44,
In addition, the heat insulating material for side 44c is a heat insulating material for oblique side 44c in the middle part.
The other end face is in contact with the end face of the bottom heat insulating material 44b. However, in the modified example, the heat insulating material for hypotenuse 44
a and a heat insulating material 44b for the bottom side.

The bottom heat insulating material 44b is provided on the upper surface 3 of the melt 30.
Radiant heat from a high melting temperature of 0a.
b, the conductive heat is received from the bottom heat shield plate 42b by heat conduction. Since the bottom-side heat insulating material 44b is disposed closer to the melt 30 than the oblique-side heat insulating material 44a, it has a higher heat quantity than the oblique-side heat insulating material 44a.
The amount of heat of the bottom side heat insulating material 44b is equal to that of the hypotenuse side heat insulating material 44a.
Smaki Sa provided between the heat insulating material 44b and the bottom heat insulating material 44b blocks the heat without conducting heat to the heat insulating material 44a for the oblique side. Accordingly, the heat transfer amount of the bottom side heat insulating material 44b is not conducted to the oblique side heat insulating material 44a, and the oblique side heat insulating material 44a can maintain a low heat amount.

As described above, the lower side of the heat insulating material 44a for the oblique side does not conduct a high amount of heat from the heat insulating material 44b for the bottom side, and high heat radiation propagates from the heat insulating material 44a for the oblique side to the single crystal 36. And the temperature gradient of the single crystal 36 can be increased.

The end face of the middle portion of the upper oblique side heat insulating material 44a and the end surface of the side heat insulating material 44c are connected to the side heat insulating material 44c.
When the upper side receives the heat radiation of the heater 28, a gap is provided to block the conduction heat, and when the upper side of the side heat insulating material 44c does not receive the heat radiation of the heater 28, the upper side of the side heat insulating material 44c is brought into contact to reduce the heat amount of the oblique side heat insulating material 44a. The escape temperature may be increased by transmitting the heat to the side heat insulating material 44c by heat conduction.

As described above, the temperature gradient of the single crystal 36 facing the side heat shield plate 42c can be increased, and the size of the grown-in defect of the single crystal 36 can be easily eliminated during annealing. It can be made minute.

FIG. 4 shows an example of an embodiment in which the radiation screen 40A is a scalene triangle. The upper portion of the radiation screen 40A is connected to support screens 60 and 62 fixed to the chamber 22 via an annular rim 46, as in FIG. The radiation screen 40A, its hypotenuse 50a,
The heat shield plate 52 includes a heat shield plate 52 having a predetermined thickness including a bottom side 50b and a side edge 50c, and a heat insulator 54 having a predetermined thickness attached to each side of the heat shield plate 52. The oblique side heat shield plate 52a of the oblique side 50a of the radiation screen 40A is formed such that the oblique side 50a on the inner surface side facing the single crystal 36 has an inverted truncated cone shape, and gradually decreases toward the single crystal 36 toward the melt 30 side. Is formed. Also, the bottom 50
The heat shield plate 52b for the bottom of b is inclined so as to gradually expand at a predetermined distance from the upper surface 30a of the melt 30 near the melt 30 on the inner side near the single crystal 36 and near the outer crucible 26. It is formed. The side heat shielding plate 52c of the side 50c is disposed substantially in parallel with a predetermined interval along the inner wall 26a of the crucible 26.

Thus, when the radiation screen 40A is a scalene triangle, when the inert gas 64 flows inside, the flow between the melt 30 and the bottom 50b becomes smooth, and the upper surface 30a of the melt 30 Does not wave out, the surface of the melt is stabilized, and a stable growth interface of the single crystal 36 is obtained. Further, the radiation screen 40A has a space Mb having a predetermined area or more inside. Further, the materials, thicknesses, and the like of the heat shield plate 52 and the heat insulating material 54 are substantially the same as those in the embodiment of FIG.

In the above configuration, a single crystal 36 is manufactured as follows. First, in a crucible 26, a silicon polycrystal, which is a single crystal material, is heated and melted by a heater 28 to form a melt 30. Then, the seed crystal 34 connected to the support means 32 is once immersed in the melt 30 in the crucible 26 and then pulled up while rotating the seed crystal 34 from the melt 30, so that the seed crystal 34 Rod-shaped single crystal 3
6 is manufactured. Single crystal 36 pulled from melt 30
After passing through a first temperature region G1 (silicon melting point 1412 ° C. to 1350 ° C.) near the melt 30, a second temperature region G 2 (1150 ° C. to 10
80 ° C). The first temperature gradient in the temperature region near the melt 30 is G1 (° C./min), the second temperature gradient in the crystal defect formation temperature region is G2 (° C./min), and the pulling speed of the single crystal 36 is V And

As described above, the size of the crystal defect generated in the single crystal 36 is determined by the cooling rate Cv, which is the product of the second temperature gradient G2 in the crystal defect formation temperature region and the pulling rate V of the single crystal.
It is known from experiments that it is almost determined by (Cv = G2 × V).

In this embodiment, the radiation screen 4
Reference numerals 0 and 40A denote heat shield plates 42 and 52 having a substantially triangular hollow cross-section and having oblique sides 40a and 50a on the inner surface facing the single crystal 36 having an inverted truncated cone shape.
And heat insulating materials 44 and 54 attached to the inside. Since the inner surfaces of the heat insulating materials 44 and 54 attached to each side have spaces Ma and Mb of a predetermined area or more surrounded by the heat insulating materials 44 and 54, they are described in the column of operation. The oblique sides 40a, 5a of the heat shielding plates 42, 52 facing the single crystal 36
0a indicates that the amount of heat received is small.
Since the amount of heat that propagates from 2 to the surface of the single crystal 36 is reduced, the first temperature region G1 near the melt 30 of the single crystal 36 and the second temperature gradient G2 in the crystal defect formation temperature region can be increased.

Accordingly, the pulling speed V can be increased, whereby the second temperature gradient G2 and the pulling speed V
Can be increased. Table 1 shows the results of the conventional example and the present embodiment. In Table 1, the critical pulling speed V, the first temperature gradient G1 in the crystal axis direction, the second temperature gradient G2 in the crystal axis direction, and the cooling speed Cv are shown. If the pulling speed V is too large with respect to the first temperature gradient G1 in the crystal axis direction during crystal growth, bending or deformation occurs. Here, the pulling speed V shown represents a pulling limit speed at which no bending or deformation occurs.

[0036]

[Table 1]

In the single crystal manufacturing apparatus 20 according to the present embodiment, the pulling speed V can be increased by increasing the first temperature region G1 near the melt 30, and the second temperature gradient G2 can be reduced. Can also be increased.
Therefore, by increasing the cooling rate Cv,
Grown- formed in the temperature region of the second temperature gradient G2.
The defect size of the in defect can be reduced as shown in FIG. FIG. 5 shows the level of the heat shield plate on the horizontal axis and the defect size of the grown-in defect on the vertical axis, and shows the grown-in defect size (nm) of the present invention and the related art. In the figure, the white circles indicate the average value, and the average defect size of the present invention can be reduced by at least about 20 nm or more on average compared with the prior art.

After the single crystal 36 is manufactured as described above, a wafer (not shown) is manufactured from the single crystal 36, and a heat treatment is performed at a temperature of 1200 ° C. for 30 minutes in a hydrogen atmosphere, and the oxide film withstand voltage ratio (GOI). Was confirmed. As a result, as shown in Table 2, the oxide film breakdown voltage non-defective rate (GOI)
Means that although it is poor in as-grown, after the hydrogen heat treatment, the yield rate is almost the same as that of the conventional example, and especially after the polishing of 3 μm, it is greatly improved and the defect-free region can be secured to the inside of the wafer. Was confirmed.

[0039]

[Table 2]

This is because the cooling rate Cv can be increased, so that the defect size (nm) becomes smaller and the as-grow
At the time of n, the oxide film breakdown voltage non-defective rate (GOI) is deteriorated, but the defect size (nm) is small, so that the defects in the surface layer of the wafer are effectively eliminated by the hydrogen heat treatment, the same non-defective rate is obtained, and 3 μm polishing is performed. Later, the defect-free area is greatly improved to the inside of the wafer, and a good oxide film breakdown voltage non-defective rate (G
OI) can be secured. Although the above description is made in a hydrogen atmosphere, a similar effect can be obtained in an argon atmosphere.

FIG. 6 is an explanatory view of a single crystal manufacturing apparatus 20A according to the second embodiment of the present invention. The same components as those in the second embodiment are denoted by the same reference numerals, and description thereof will be omitted. FIG.
As shown in FIG.
And supporting the radiation screen 40 </ b> A, the same effect as in the above embodiment can be obtained. If a cylindrical member is used as the holding means 66, the gas flow can be improved by the rectifying action. In this case, the DFC conversion ratio (Di) is higher than when the rod-shaped holding unit 66 is used.
location free crystal).

[0042]

As described above, in the single crystal manufacturing apparatus and the single crystal manufacturing method according to the present invention, the axial temperature gradient in the vicinity of the pulling interface and the defect forming temperature region in single crystal pulling is increased, and the crystal pulling is performed. By increasing the upper speed, a single crystal rod having a reduced defect size of the grown-in defect can be manufactured. By subjecting the wafer cut from this single crystal rod to heat treatment in a non-oxidizing atmosphere containing hydrogen gas, defects can be effectively eliminated by the hydrogen heat treatment, and an equivalent yield can be obtained by the hydrogen heat treatment. At the same time, it is possible to secure a wafer having a good oxide film withstanding voltage ratio (GOI) in which the defect-free region is significantly improved inside the wafer, to improve the yield in devices, and to manufacture a high-quality single crystal. Can be.

[Brief description of the drawings]

FIG. 1 is an overall conceptual side view of a single crystal manufacturing apparatus according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged side view of the first embodiment of the single crystal manufacturing apparatus of the present invention.

FIG. 3 is a partially enlarged view of a radiation screen section of the single crystal manufacturing apparatus of the present invention.

FIG. 4 is a side view of a trapezoidal embodiment of the radiation screen of the present invention.

FIG. 5 is a graph showing defect sizes in a conventional example and the present invention.

FIG. 6 is an overall conceptual side view of a single crystal manufacturing apparatus according to a second embodiment of the present invention.

FIG. 7 is a partial conceptual side view for explaining the operation of the single crystal manufacturing apparatus of the present invention.

FIG. 8 is a partial conceptual side view for explaining the operation of a conventional single crystal manufacturing apparatus.

FIG. 9 is a partial conceptual side view for explaining the operation of another conventional single crystal manufacturing apparatus.

FIG. 10 is an explanatory diagram showing the amount of heat received by the shielding plate according to the distance from the melt of the related art and the present invention.

FIG. 11 is a side view of a first example of a conventional single crystal manufacturing apparatus.

FIG. 12 is a side view of a second example of a conventional single crystal manufacturing apparatus.

FIG. 13 is a side view of a third example of a conventional single crystal manufacturing apparatus.

[Explanation of symbols]

 20, 20A Single crystal manufacturing apparatus 22 Chamber 24 Top chamber 26 Crucible 28 Heater 29 Warm wall 30 Melt 32 Support means 34 Seed crystal 36 Single crystal 40, 40A Radiation screen 42, 52 Heat shield plate 42a, 52a Oblique heat shield plate 42b, 52b Bottom heat shield 42c, 52c Side heat shield 44, 54 Insulation 44a, 54a Oblique heat insulation 44b, 54b Bottom heat shield 44c, 54c Side heat shield 64 Inert gas V Lifting speed G1 First temperature gradient G2 Second temperature gradient Cv Cooling speed (Cv = V * G2) Ma, Mb Space Sa Clearance

Continued on the front page (72) Inventor Hiroki Nakajima 2612 Yonomiya, Hiratsuka-shi, Kanagawa F-term (reference) 4G077 AA02 BA04 CF10 EG19 EG20 EG25 FE02 PE22

Claims (3)

[Claims] 1. A crucible for holding a melt as a single crystal material, a heater around the crucible for heating the melt, and a vertically movable support means positioned above the melt in the crucible. A radiation screen surrounding the single crystal growing below the seed crystal connected to the support means, wherein the radiation screen is formed in an annular shape surrounding the single crystal with a substantially triangular cross section in a hollow shape. At the same time, a heat insulating material of a predetermined thickness is attached inside the heat shield plate that is disposed so that the inner surface facing the single crystal is gradually reduced to an inverted truncated cone shape, and a space that reduces radiant heat between the heat insulating materials is provided. An apparatus for producing a single crystal, comprising: 2. The single crystal manufacturing apparatus according to claim 1, wherein a gap for blocking conduction heat is provided on an end surface of the adjacent heat insulating material. 3. A single crystal material is heated and melted to form a melt,
In a single crystal manufacturing method for manufacturing a single crystal by dipping a seed crystal in the melt and pulling the same, the single crystal faces a single crystal in a defect formation temperature region of 1150 to 1080 ° C. through which the single crystal passes when pulled. A radiation screen having a space between heat insulating materials provided inside a heat shield plate having a hollow triangular cross section on the inner surface side having an inverted truncated cone shape and having a hollow triangular cross section is provided to increase a temperature gradient in a defect forming temperature region. Space
Using this radiation screen, the single crystal is pulled at a high pulling speed to increase the product of the temperature gradient and the pulling speed, and
A single crystal rod is manufactured by making the defect size of the n-in defect minute, and the wafer is cut from the single crystal rod, and then the wafer is heat-treated in a non-oxidizing atmosphere containing hydrogen gas or argon gas. A method for producing a single crystal, characterized in that the inside of a wafer is free from defects.