JP2003321297A - Method for producing silicon single crystal and silicon single crystal wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a non-defective silicon single crystal wafer having high withstand voltage and excellent electrical properties by producing a silicon single crystal which does not belong to any of the V-region rich in vacancy, an OSF region and the I-region rich in interstitial silicon and can securely improve electrical properties such as dielectric strength of an oxide film, with high-speed and stability. <P>SOLUTION: A method for producing a silicon single crystal by Czochralski process comprises bringing a seed crystal into contact with silicon melt 2 contained in a crucible 32 and then pulling-up the seed crystal while rotating it to grow the silicon crystal 1. The crucible is not rotated or rotated in the same direction as the direction for rotating the seed crystal. The crystal is grown in an N-region outside of the OSF formed in a ring-form at the thermal oxidation treatment, which is a non-defective region in which the defective region detected by Cu-deposition is not present. Preferably, the silicon melt is applied with a horizontal magnetic field, and the rotation speed of the crucible is within 0-2 rpm. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
There are no defects in the region, I region, and OSF region,
In addition, the present invention relates to a method for producing a silicon single crystal in a defect-free region free of defects detected by Cu deposition at high speed and stably.

[0002]

2. Description of the Related Art In recent years, along with the miniaturization of elements accompanying the high integration of semiconductor circuits, quality requirements for a silicon single crystal, which is a substrate thereof, manufactured by the Czochralski method (CZ method) is increasing. . Especially FPD, LSTD, CO
There is a defect due to single crystal growth, which is called a grown-in defect such as P, which deteriorates the oxide film withstand voltage property and the device property, and it is important to reduce the density and size thereof.

In explaining these defects, first, a vacancy (Va) incorporated in a silicon single crystal is used.
vacancies, hereinafter abbreviated as "V"), and vacancies, and interstitial silicon called interstitial-Si (hereinafter sometimes abbreviated as "I"). We will explain what is generally known about the factors that determine the incorporated concentration of each of the point defects.

In a silicon single crystal, the V region is V
i.e., an area where there are many recesses, holes, etc. that arise from lack of silicon atoms, and the I area is
This is a region in which dislocations caused by the existence of extra silicon atoms and a large amount of extra silicon atoms are present. Further, between the V region and the I region, there is a neutral (Neutral, sometimes abbreviated as N hereinafter) region in which there is no shortage or excess of atoms. Then, the grown-in defects (FPD, LSTD, CO
(P, etc.) is generated as a result of agglomeration of point defects when V and I are supersaturated.
It has been found that the point defects do not agglomerate and do not exist as the grown-in defects if they are saturated or less, even if the atoms are slightly biased.

The concentration of these two point defects is determined by the relationship between the pulling rate (growth rate) of the crystal in the CZ method and the temperature gradient G near the solid-liquid interface in the crystal, and is near the boundary between the V region and the I region. Is OSF (oxidation-induced stacking fault, Oxidati)
on Induced Stacking Faul
It has been confirmed that defects called t) are distributed in a ring shape (hereinafter sometimes referred to as an OSF ring) when viewed in a cross section in a direction perpendicular to the crystal growth axis.

These defects caused by crystal growth can be observed in a CZ pulling machine using a normal furnace internal structure (hot zone: HZ) having a large temperature gradient G in the vicinity of the solid-liquid interface in the crystal from a high growth rate in the crystal axis direction. When the speed is changed to a low speed, the defect distribution map as shown in FIG. 6 is obtained.

When the defects caused by the crystal growth are classified, for example, when the growth rate is relatively high such as around 0.6 mm / min or more, it is considered that the FPD is caused by voids in which vacancy type point defects are aggregated. , LSTD, COP, and other grown-in defects are present at a high density over the entire crystal radial direction, and the region where these defects are present is called the V region (line (A) in FIG. 6). Also, the growth rate is 0.6 mm / min
In the following cases, the L / D is considered to be caused by the dislocation loop in which the OSF ring is generated from the periphery of the crystal along with the decrease in the growth rate and the interstitial silicon is gathered outside the ring.
(Large Dislocation: Abbreviation of interstitial dislocation loop, LSEPD, LFPD, etc.) defects (giant dislocation clusters) are present at low density, and the region where these defects are present is called I region (sometimes referred to as L / D region). being called. Further, when the growth rate is reduced to around 0.4 mm / min or less, the OSF ring contracts to the center of the wafer and disappears, and the entire surface becomes the I region (line (C) in FIG. 6).

In recent years, the OSF has been placed between the V region and the I region.
On the outside of the ring, a FP due to holes called N region
D, LSTD and COP are also LSE due to interstitial silicon
The existence of a region where neither PD nor LFPD exists has been discovered. This region is outside the OSF ring, and when oxygen precipitation heat treatment is performed and the precipitation contrast is confirmed by X-ray observation or the like, there is almost no oxygen precipitation and it is rich enough to form LSEPD and LFPD. It is reported to be the I region side which is not (line (B) of FIG. 6).

In the usual method, these N regions exist obliquely with respect to the growth axis direction when the growth rate is lowered, so that they exist only in a part of the wafer surface (for example, the line in FIG. 6). In the case of (B), only the wafer peripheral portion outside the OSF ring). For this N region,
Boronkov theory (V.V. Voronkov; Jour
nal of Crystal Growth, 59
(1982) 625-643), pulling speed (V)
And V / G, which is the ratio of the temperature gradient (G) in the crystal-solid interface
The parameter says that it determines the total density of point defects. Considering this, the pulling rate (growth rate) should be almost constant in the plane, so G
Has a distribution, so that, for example, at a certain pulling rate, only a crystal having the center in the V region and the N region sandwiching the I region in the periphery was obtained.

Therefore, recently, by improving the in-plane G distribution,
When the N-region that existed only obliquely is pulled up while gradually lowering the pulling rate (growth rate), the N region is laterally entire surface (entire wafer surface) at a certain pulling rate.
It has become possible to produce crystals that have spread to the. In order to expand the crystal in the entire N region in the length direction, it can be achieved to some extent by pulling while maintaining the pulling rate when the N region spreads laterally. Also, as the crystal grows, G
If the pulling speed is adjusted so that V / G is kept constant, considering that the value changes,
As a result, the crystal that becomes the entire N region can be expanded in the growth direction.

However, as described above, the entire surface is the N region, an OSF ring is not generated during the thermal oxidation process, and an oxide film defect is generated even though the FPD and L / D are not present on the entire surface. Was found to occur remarkably. This causes electrical characteristics such as oxide film withstand voltage characteristics to deteriorate, and it is not enough that the conventional entire surface is the N region, and further improvement in quality has been desired.

Further, in order to pull up the crystal in the N region as described above, the pulling rate must be lower than that of the crystal in the V region, which is a conventional crystal, and the control range is narrow, so that the crystal production is remarkable. There is a problem that the sex is lowered. In order to meet the recent increase in demand for semiconductors and cost reduction, it is also necessary to manufacture high-quality silicon single crystals at high speed and stably.

[0013]

Therefore, the present invention belongs to any of the V region rich in vacancies, the OSF region, and the I region rich in interstitial silicon when the silicon single crystal is manufactured by the Czochralski method. In addition, the silicon single crystal that can reliably improve the electrical characteristics such as the oxide film breakdown voltage is manufactured at high speed and stably, and the defect-free silicon single crystal wafer with high breakdown voltage and excellent electrical characteristics can be manufactured at low cost. The purpose is to provide.

[0014]

In order to achieve the above object, according to the present invention, a seed crystal is brought into contact with a silicon melt contained in a crucible, and then the seed crystal is pulled up while rotating the silicon single crystal. In the method for producing a silicon single crystal by the Czochralski method for growing a crystal, the crucible is rotated without rotating or in the same direction as the rotation direction of the seed crystal, and ring-shaped when subjected to thermal oxidation treatment. A method for producing a silicon single crystal, which comprises growing a crystal in a defect-free region outside the OSF, which is the N region outside of the defect region detected by Cu deposition. 1).

According to such a manufacturing method, when the grown crystal is used as a wafer, the FPD in the V region is entirely covered.
Such as defects, large dislocation clusters in the I region (LSEPD, L
FPD) and an N region where an OSF defect is not formed, and a defect (C
It is possible to manufacture a defect-free silicon single crystal having no u-deposition defect) at a higher speed and more stably than ever before.

Further, according to the present invention, after a seed crystal is brought into contact with the silicon melt contained in the crucible, the seed crystal is pulled while rotating to grow a silicon single crystal. In the method for producing a crystal, when the crucible is not rotated or is rotated in the same direction as the rotation direction of the seed crystal and the growth rate of the silicon single crystal being grown is gradually reduced, the Cu depletion remaining after the OSF ring disappears. To grow a crystal by controlling the growth rate between the boundary growth rate at which the defect region detected by the position disappears and the boundary growth rate at which an interstitial dislocation loop occurs when the growth rate is further reduced. A method for producing a silicon single crystal is also provided (claim 2).

Even with such a method, VPD of FPD or the like can be obtained.
Region defect, I region defect such as giant dislocation cluster, and OS
A defect-free silicon single crystal in which no F defects are formed and no Cu deposition defects are present can be manufactured more reliably and more rapidly than in the past.

When the silicon single crystal is produced by these methods, it is preferable to grow the silicon single crystal while applying a horizontal magnetic field to the silicon melt (claim 3).
By growing a silicon single crystal while applying a horizontal magnetic field to the silicon melt in this manner, convection of the melt can be suppressed and a defect-free silicon single crystal can be grown more stably.

Further, it is preferable that the rotation speed of the crucible be within a range of 0 to 2 rpm (claim 4). Thus, if the silicon single crystal is grown without rotating the crucible (rotation speed: 0 rpm) or by rotating the crucible in the same direction as the rotation direction of the seed crystal at a rotation speed of 2 rpm or less, a defect-free silicon single crystal is obtained. It can be raised at a higher speed.

A defect-free silicon single crystal wafer is provided which is obtained by slicing a silicon single crystal grown by the above method (claim 5).
With such a silicon wafer, V region defects such as FPD, I region defects such as giant dislocation clusters, and OSF
It becomes a defect-free silicon single crystal wafer having no defects, no Cu deposition defects, high breakdown voltage and excellent electrical characteristics, and is inexpensive because it is grown at high speed.

The present invention will be described in detail below, but the present invention is not limited thereto. Prior to the explanation, each term mentioned above will be explained in advance. 1) FPD (Flow Pattern Defec)
In t), the wafer is cut out from the grown silicon single crystal rod, the strained layer on the surface is removed by etching with a mixed solution of hydrofluoric acid and nitric acid, and then K ₂ Cr ₂ O ₇ is mixed with hydrofluoric acid and water. Etching the surface with a liquid (Secco etching) produces pits and ripples. This ripple pattern is referred to as FPD, and the higher the FPD density in the wafer surface, the more defective the oxide film withstand voltage becomes (Japanese Patent Laid-Open No. 19234/1992).
(See Japanese Patent Publication No. 5).

2) SEPD (Secco Etch P)
it Defect) is the same Secco as FPD.
When etching is applied, the flow pattern (flow pattern
The one with tern) is called FPD, and the one without flow pattern is called SEPD. Among them, a large SEPD (LSEPD) of 10 μm or more is considered to be caused by dislocation clusters, and when dislocation clusters exist in the device, current leaks through these dislocations, and the function as a P-N junction cannot be achieved.

3) LSTD (Laser Scatter)
In the ring tomography defect, a wafer is cut out from a grown silicon single crystal ingot, the strained layer on the surface is removed by etching with a mixed solution of hydrofluoric acid and nitric acid, and then the wafer is cleaved. Infrared light is incident from this cleavage plane and the light emitted from the surface of the wafer is detected, so that scattered light due to defects existing in the wafer can be detected. The scatterers observed here have already been reported in academic societies and are regarded as oxygen precipitates (Jpn. J. Appl. Phys. Vol. 32,
P3679, 1993). Also, in recent research,
Results have also been reported to be octahedral voids.

4) COP (Crystal Origin)
Nated Particle) is a defect that causes deterioration of the breakdown voltage of the oxide film at the center of the wafer.
The defect that becomes FPD by co etching is SC-1 cleaning (N
H ₄ OH: H ₂ O ₂ : H ₂ O = 1: 1: 10 mixed solution) acts as a selective etching solution and becomes a COP. The pit has a diameter of 1 μm or less and is examined by a light scattering method.

5) L / D (Large Disloca)
(abbreviation for interstitial dislocation loop), LSEP
D, LFPD, and the like, which are defects that are considered to be caused by dislocation loops in which interstitial silicon is aggregated. LSEPD
Means a large one of 10 μm or more among the SEPDs as described above. In addition, the LFPD refers to a large tip pit having a size of 10 μm or more among the above FPDs, which is also considered to be caused by a dislocation loop.

6) The Cu deposition method is capable of accurately measuring the position of defects in a semiconductor wafer, improving the detection limit for defects in the semiconductor wafer, and accurately measuring and analyzing even finer defects. Is an evaluation method of.

A specific method for evaluating a wafer is to form an insulating film having a predetermined thickness on the surface of the wafer, destroy the insulating film on the defective portion formed near the surface of the wafer, and to form Cu on the defective portion. It deposits (deposits) an electrolytic substance such as. That is, in the Cu deposition method, when a potential is applied to an oxide film formed on the surface of a wafer in a liquid in which Cu ions are dissolved, a current flows through a site where the oxide film is deteriorated and Cu ions become Cu. It is an evaluation method that utilizes the fact that it precipitates. C on the part where the oxide film is likely to deteriorate
It is known that defects such as OP exist.

The defective portion of the Cu-deposited wafer can be analyzed under a concentrating lamp or directly with the naked eye to evaluate its distribution and density, and further, it can be observed by a microscope, a transmission electron microscope (TEM) or a scanning. It can also be confirmed with an electron microscope (SEM) or the like.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present inventors have conducted a detailed investigation on the vicinity of the boundary between the V region and the I region regarding the growth of a silicon single crystal by the CZ method.
A neutral N region where the number of FPDs, LSTDs, and COPs was extremely small and L / D did not exist was found outside the SF ring.

However, N without the above-mentioned defect
Even if crystals were grown in the region, there were some oxide film withstand voltage characteristics that were poor, and the cause was not well understood. Therefore, the inventors of the present invention investigated the N region in more detail by the Cu deposition method. As a result, the Cu deposition was observed in a part of the N region outside the OSF region where oxygen precipitation was likely to occur after the precipitation heat treatment. It has been discovered that there are areas where defects detected in the process occur significantly. Then, it was found that this is a cause of deteriorating electrical characteristics such as oxide film withstand voltage characteristics.

Therefore, if the N region outside the OSF, which has no defect region detected by Cu deposition, can be spread over the entire surface of the wafer, the various grown-in defects will not occur and the oxide film can be surely formed. A wafer capable of improving withstand voltage characteristics and the like can be obtained.

Then, in the N region outside the OSF,
By growing a single crystal at a rate between the growth rate at which the Cu deposition defect region disappears and the growth rate at the I region where the giant dislocation cluster appears (hereinafter, sometimes referred to as defect-free region growth rate). It has been found that it is possible to obtain a defect-free silicon single crystal wafer which does not have the various grown-in defects described above and can surely improve the oxide film withstand voltage characteristics and the like.

However, the growth rate of such a defect-free region needs to be lower than the pulling rate of the conventional single crystal, and the control range is narrow, so that the manufacturing cost of the single crystal is significantly increased. Therefore, it is necessary to improve the growth rate of the defect-free region.

Therefore, the inventors of the present invention further investigated and found that there was a correlation between the number of rotations of the crucible and the growth rate of the defect-free region, and it was found that by rotating the crucible without rotating it or in the same direction as the rotation direction of the seed crystal. It was found that the growth rate of the defect-free region can be increased.

The present invention has been completed based on these findings, that is, the crucible is not rotated or is rotated in the same direction as the rotation direction of the seed crystal, and a ring shape is formed when the thermal oxidation treatment is performed. N outside the OSF
The present invention is characterized in that the crystal is grown in a defect-free region where no defect region detected by Cu deposition exists. Hereinafter, the present invention will be described in more detail with reference to the drawings, but the present invention is not limited thereto.

FIG. 1 (a) shows an example of a single crystal pulling apparatus that can be used in the present invention. This single crystal pulling apparatus 30 includes a pulling chamber 31, a crucible 32 provided in the pulling chamber 31, a heater 34 arranged around the crucible 32, a crucible holding shaft 33 for rotating the crucible 32, and a rotation mechanism thereof. (Not shown), a seed chuck 6 for holding a silicon seed crystal, a wire 7 for pulling up the seed chuck 6, and a winding mechanism (not shown) for rotating or winding the wire 7. Further, a heat insulating material 35 is arranged around the outside of the heater 34.

The crucible 32 is provided with a quartz crucible on the inner side for accommodating the silicon melt (hot water) 2 and a graphite crucible on the outer side. A positive / negative rotation changeover switch is provided so that the crucible holding shaft 33 can be rotated in either the left or right direction by the rotation mechanism. As shown in FIG. 1B, the crucible 32 is rotated in the rotation direction of the seed crystal (upper direction). It can be rotated in the same direction as the shaft rotation direction) or in the opposite direction.

An annular graphite cylinder (heat shield plate) 9 is provided in order to set the manufacturing conditions relating to the manufacturing method of the present invention, and further the annular outer side is provided on the outer periphery in the vicinity of the solid-liquid interface 4 of the crystal. A heat insulating material 10 is provided. This outer insulation 10
Is 2 to 2 between the lower end and the molten metal surface 3 of the silicon melt 2.
It is installed with a space of 0 cm. Furthermore, a cylindrical cooling device may be provided that blows a cooling gas or blocks radiant heat to cool the single crystal. By doing so, the difference between the temperature gradient Gc [° C./cm] in the crystal center portion and the temperature gradient Ge in the crystal peripheral portion becomes small, and for example, the temperature in the furnace is set so that the temperature gradient in the crystal peripheral portion becomes lower than that in the crystal center. Can also be controlled.

Further, a superconducting magnet 36 for applying a horizontal magnetic field (transverse magnetic field) to the silicon melt 2 in the crucible 32 is provided outside the pulling chamber 31 in the horizontal direction. As a result, the silicon single crystal can be pulled up by the so-called H-MCZ method in which the convection of the melt 2 is suppressed and the single crystal is stably grown. The magnet 3
6 may be a normal conduction type.

In order to manufacture a silicon single crystal using such a single crystal pulling apparatus 30, first, a high-purity polycrystalline raw material of silicon is melted (about 1420 ° C.) in a crucible 32.
Heat to above and melt. Next, the tip of the seed crystal is brought into contact with or immersed in the substantially central portion of the surface of the melt 2 by unwinding the wire 7. Then, the crucible holding shaft 33 is rotated and the wire 7 is wound while being rotated. As a result, the seed crystal is also pulled while rotating, and the growth of the single crystal is started. Thereafter, by appropriately adjusting the pulling speed and the temperature, the substantially cylindrical single crystal ingot 1 can be obtained.

At this time, conventionally, the rotation direction of the seed crystal, that is, the rotation direction of the growing single crystal rod and the rotation direction of the crucible are opposite to each other. However, in the present invention, when the silicon single crystal is grown as described above, Without rotating or in the same direction as the rotation direction of the seed crystal, which is an N region outside the OSF generated in a ring shape when a thermal oxidation treatment is performed,
Crystals are grown in a defect-free region where no defect region detected by u deposition exists.

(Experiment 1): Confirmation of Crystal Growth Rate in Defect-Free Region In order to confirm the conditions for growing a defect-free silicon single crystal using the above-described single crystal manufacturing apparatus 30, the crystal was grown as follows. An experiment of gradually reducing the growth rate was performed, and FPD, LFPD, LSEPD, and OSF of the obtained single crystal were confirmed, and the oxide film breakdown voltage characteristic was evaluated.

First, 150 kg of polycrystalline silicon as a raw material was charged in a quartz crucible having a diameter of 24 inches (600 mm) to grow a silicon single crystal having a diameter of 8 inches (200 mm) and an orientation of <100>. Here, when a single crystal is grown, the growth rate is 0.
It was controlled to gradually decrease from 8 mm / min to 0.4 mm / min.

Such a gradual decrease experiment of the crystal growth rate was conducted by setting the crucible at various rotation speeds. Specifically, with the crucible stopped (0 rpm), or 0.1 rpm in the same direction as the rotation direction of the seed crystal (upper axis rotation direction),
0.3 rpm, 0.5 rpm, 1.0 rpm, 2.0r
pm, 3.0 rpm, and 0.1 rpm, 1.0 rpm, 2.0 rpm in the opposite direction to the seed crystal. In any case, during the growth of the single crystal, the magnetic field strength at the center of the single crystal was 400
A horizontal magnetic field was applied by a superconducting method so as to obtain 0 G. The magnetic field strength is not particularly limited, but it is suitable to apply a horizontal magnetic field having a central magnetic field strength of about 500 to 5000 G, for example. The following evaluation was performed on each silicon single crystal grown as described above.

Evaluation method (1) The straight body portion of each grown single crystal ingot was set to 10 in the crystal axis direction.
After cutting into blocks each having a length of cm, each block was further cut in the crystal axis direction to prepare a sample having a thickness of about 2 mm. (2) FPD, LFPD, LSE for the above samples
The PD and OSF were confirmed. Specifically, each sample was surface-ground, then mirror-etched and seco-etched (30 minutes), left without stirring, and subjected to a predetermined treatment, and the density of each defect was measured. Regarding the evaluation of OSF, after heat treatment at 1150 ° C. for 100 minutes (in a wet oxygen atmosphere), cooling (putting in / out at 800 ° C.),
After removing the oxide film with a chemical solution, the OSF ring pattern was confirmed and the density was measured. (3) Further, defect evaluation by Cu deposition was also performed. One of the samples cut longitudinally in the crystal axis direction was hollowed into a wafer shape with a diameter of 6 inches, mirror-finished by polishing, and Cu deposition processing was performed after oxide film formation to remove oxide film defects. The distribution status was confirmed. At that time, the evaluation conditions are as follows. Oxide film: 25 nm Electric field strength: 6 MV / cm Voltage application time: 5 minutes

Evaluation Results According to the above evaluation, in each silicon single crystal,
It was possible to confirm a defect-free region in which a defect region detected by Cu deposition does not exist in the N region outside the OSF generated in a ring shape when the thermal oxidation process is performed. FIG. 2 shows the relationship between such a defect-free region and its growth rate. From this figure, when the growth rate of the growing silicon single crystal is gradually reduced, the growth rate at the boundary where the defect region detected by the Cu deposition remaining after the OSF ring disappears disappears, and when the growth rate further decreases Between the growth rate at the boundary where the interstitial dislocation loop (giant dislocation cluster: I region) occurs is the N region outside the OSF, and Cu
It can be specified as a growth rate (defect-free area growth rate) that becomes a defect-free area in which a defect area detected by deposition does not exist.

The defect-free region growth rate of each silicon single crystal was determined as described above and is shown in Table 1. Furthermore, the relationship between the number of rotations of the crucible and the growth rate of the defect-free region is graphed in FIG. The defect-free region growth rate shown in Table 1 and FIG. 3 is an intermediate value between the Cu deposition defect disappearance rate and the giant dislocation cluster (LSEPD, LFPD) generation rate.

[0048]

[Table 1]

As is clear from Table 1 and FIG. 3, when the crucible is rotated in the direction opposite to that of the seed crystal, the smaller the number of rotations, the higher the defect-free region growth rate.
It is less than 7 mm / min. On the other hand, when the crucible is stopped or the crucible is rotated in the same direction as the seed crystal to grow the crystal, both are 0.57 mm / min.
The above defect-free region growth rate has been achieved. Therefore,
For example, the defect-free region growth rate of at least near 0.58 mm / min is achieved by rotating the crucible without rotation or by rotating the crucible in the same direction as the rotation direction of the seed crystal at a rotation speed within the range of 0 to 2 rpm. Can, in particular, 0-1
With rpm, a higher defect-free region growth rate of 0.585 mm / min or more can be achieved.

From the above experiment, when the silicon single crystal is manufactured by the Czochralski method using the apparatus as shown in FIG. 1, the crucible is not rotated or is rotated in the same direction as the rotation direction of the seed crystal. In addition, in the N region outside the OSF generated in a ring shape when the thermal oxidation process is performed, in the defect-free region where the defect region detected by Cu deposition does not exist, in other words, the silicon under growth. When the growth rate of the single crystal is gradually reduced, the growth rate of the boundary where the defect region detected by the Cu deposition remaining after the OSF ring disappears disappears, and the boundary where the interstitial dislocation loop occurs when the growth rate is further decreased By growing the crystal while controlling the growth rate between the growth rate and the growth rate, the silicon single crystal in which the entire crystal is a defect-free region can be grown at high speed. In particular, the crucible is in the same direction as the seed crystal,
Preferably 0-2 rpm, more preferably 0-1 rp
By rotating at a rotation speed in the range of m, a defect-free silicon single crystal can be grown at a higher speed.

Therefore, by slicing the silicon single crystal ingot grown by such a method, the entire surface is defect-free, that is, V region defects such as FPD, I region defects such as giant dislocation clusters, and OSF defects are included. In addition, it is possible to efficiently obtain a high-quality silicon wafer having a high breakdown voltage and excellent electrical characteristics, which is free from defects detected by Cu deposition.

(Experiment 2): Relationship between rotation of crucible and temperature gradient of solid-liquid interface of crystal In order to grow a crystal having an N region on the entire surface in the growth direction, V / G should be kept constant as described above. You can adjust the pulling speed. Therefore, if G can be increased, the pulling speed V also increases (V / G is constant),
It is possible to grow a crystal that becomes the entire N region. Therefore, in order to verify the results obtained in Experiment 1, the relation between the rotation of the crucible and the temperature gradient (G) in the crystal solid-liquid interface was calculated by using the comprehensive heat transfer analysis software “IHTCM” (for details, TAKinne
y, DEBornside, RABrown and KMKim, Journal of
Crystal Growth, vol.126, pp413, (1993) and TA Kinney
and RABrown, Journal of Crystal Growth, vol.132,
pp551, (1993)), the convection simulation calculation was performed, and the temperature gradient (G) in the axial direction at the crystal-solid interface was investigated. The results are shown in Fig. 4.

As is clear from FIG. 4, the crucible is not rotated or is rotated in the same direction (upper axis rotation direction) as compared with the case where the crucible is rotated in a direction opposite to the rotation direction of the seed crystal (anti-upper axis rotation direction). It is understood that the temperature gradient G in the crystal solid-liquid interface axial direction becomes higher when rotated to (). From the result of the above simulation, G can be increased without rotating the crucible or in the same direction as the rotation direction of the seed crystal, and the defect-free region growth rate when growing a defect-free silicon single crystal. It is considered that V can also be speeded up. That is, it supports the results obtained in Experiment 1.

(Experiment 3): Control of Oxygen Concentration in Crystal When the crystal is pulled up with the rotation speed of the crucible kept constant, the oxygen concentration in the single crystal decreases toward the latter half of the straight body. Therefore, the crucible was rotated in the same direction as the seed crystal, and the straight body portion of the crystal was grown while gradually increasing the number of rotations of the crucible, and the initial oxygen concentration in the straight body portion of the obtained silicon single crystal was set to 20 c.
The measurement was performed every m. The results are shown in Fig. 5. As is clear from this graph, the oxygen concentration in the first part of the straight body part that was grown without rotating the crucible was lowered,
It can be seen that the oxygen concentration in the latter half of the straight body can be increased and the oxygen concentration of the entire single crystal ingot can be kept substantially constant. Also, for example, if the target oxygen concentration is lower,
When the crucible is stopped and grown under conditions close to (0 rpm), a defect-free silicon single crystal with a low oxygen concentration can be grown.

The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, has substantially the same configuration as the technical idea described in the scope of the claims of the present invention, and has any similar effect to the present invention. It is included in the technical scope of the invention.

For example, the apparatus used for producing a silicon single crystal according to the present invention is not limited to the apparatus shown in FIG. 1, but the crucible can be rotated in the same direction as the seed crystal, and the thermal oxidation treatment can be performed. OSF generated in a ring shape when
The apparatus can be used without limitation as long as it is an apparatus that can manufacture a silicon single crystal in the N region outside the region, which is a defect-free region where a defect region detected by Cu deposition does not exist. For example, crystal growth may be performed without applying a horizontal magnetic field.

[0057]

As described above, according to the present invention,
The silicon single crystal in the V region, the OSF region, the I region, and the defect-free region that does not include the Cu deposition defect region can be pulled at high speed. Therefore, a silicon single crystal capable of improving electrical characteristics such as oxide film withstand voltage can be manufactured at high speed and stably, and a defect-free silicon single crystal wafer having high withstand voltage and excellent electrical characteristics can be provided at low cost. You can

[Brief description of drawings]

FIG. 1 is an example of a silicon single crystal manufacturing apparatus that can be used in the present invention. (A) Schematic diagram (b) Rotation direction of crystal and crucible

FIG. 2 is a graph showing a defect-free region growth rate.

FIG. 3 is a graph showing the relationship between the number of rotations of the crucible and the growth rate of a defect-free region.

FIG. 4 is a graph showing the relationship between the rotation of the crucible and the temperature gradient in the crystal interface axis direction.

FIG. 5 is a graph showing the relationship between the rotation speed of the crucible and the initial oxygen concentration. (A) Crucible rotation speed with respect to crystal straight body length (b) Initial oxygen concentration with respect to crystal straight body length

FIG. 6 is an explanatory diagram showing a growth rate and a defect distribution of crystals according to a conventional technique.

[Explanation of symbols]

1 ... Growth single crystal rod, 2 ... Silicon melt, 3 ... Molten surface,
4 ... Solid-liquid interface, 6 ... Seed chuck, 7 ... Wire,
9 ... Graphite cylinder, 10 ... Outside heat insulating material, 30 ... Single crystal pulling device, 31 ... Pulling chamber, 32 ... Crucible, 33 ... Crucible holding shaft, 34 ... Heater, 35 ... Heat insulating material, 36
…magnet. V ... V area, N ... N area, OSF ... OSF ring and OSF area, I ... I area.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tatsuo Mori             Odaira, Odakura, Saigo Village, Nishishirakawa-gun, Fukushima Prefecture             No. 150 Shin-Etsu Semiconductor Co., Ltd. Semiconductor Shirakawa             In the laboratory (72) Inventor Izumi Fusegawa             Odaira, Odakura, Saigo Village, Nishishirakawa-gun, Fukushima Prefecture             No. 150 Shin-Etsu Semiconductor Co., Ltd. Semiconductor Shirakawa             In the laboratory (72) Inventor Tomohiko Ota             Odaira, Odakura, Saigo Village, Nishishirakawa-gun, Fukushima Prefecture             No. 150 Shin-Etsu Semiconductor Co., Ltd. Semiconductor Shirakawa             In the laboratory F term (reference) 4G077 AA02 BA04 CF10 EH06 EH08                       PF17 PF51

Claims (5)

[Claims] 1. A method for producing a silicon single crystal by the Czochralski method in which a seed crystal is brought into contact with a silicon melt contained in a crucible and then the seed crystal is pulled up while rotating to grow a silicon single crystal, The N region outside the OSF, which is ring-shaped when the crucible is rotated without rotating or in the same direction as the rotation direction of the seed crystal and is subjected to thermal oxidation treatment, is detected by Cu deposition. A method for manufacturing a silicon single crystal, which comprises growing a crystal in a defect-free region where no defect region exists. 2. A method for producing a silicon single crystal by the Czochralski method, in which a seed crystal is brought into contact with a silicon melt contained in a crucible and then the seed crystal is pulled while rotating to grow a silicon single crystal, Defects detected by Cu deposition remaining after the OSF ring disappears when the crucible is rotated without rotating or in the same direction as the rotation direction of the seed crystal and the growth rate of the silicon single crystal during growth is gradually reduced. A silicon single crystal characterized by growing a crystal by controlling the growth rate between a boundary growth rate at which the region disappears and a boundary growth rate at which an interstitial dislocation loop is generated when the growth rate is further reduced. Crystal manufacturing method. 3. The method for producing a silicon single crystal according to claim 1, wherein the silicon single crystal is grown while applying a horizontal magnetic field to the silicon melt. 4. The rotation speed of the crucible is set within a range of 0 to 2 rpm.
A method for producing a silicon single crystal according to any one of 1. 5. A defect-free silicon single crystal wafer obtained by slicing a silicon single crystal grown by the method according to any one of claims 1 to 4.