WO2003091484A1

WO2003091484A1 - Method for producing silicon single crystal and silicon single crystal wafer

Info

Publication number: WO2003091484A1
Application number: PCT/JP2003/005243
Authority: WO
Inventors: Masahiro Sakurada; Tatsuo Mori; Izumi Fusegawa; Tomohiko Ohta
Original assignee: Shin-Etsu Handotai Co.,Ltd.
Priority date: 2002-04-25
Filing date: 2003-04-24
Publication date: 2003-11-06
Also published as: JP2003321297A

Abstract

A method for producing a silicon single crystal by the Czochralski method wherein a seed crystal is contacted with a silicon melt (2) held in a crucible (32) and the seed crystal is pulled up while being rotated, to thereby grow a silicon single crystal (1), characterized in that the crucible is not rotated or is rotated in the same direction with that of the rotation of the seed crystal, and a crystal is grown in a no defect region which is an N region being present outside OSF generating in a ring form in a heat oxidation treatment and is free from the presence of a defect region detected by Cu deposition. It is preferred that a horizontal magnetic field is applied and the crucible is rotated with a rate in the range of 0 to 2 rpm. The method allows the production, with stability at a high production rate, of a silicon single crystal which does not belong to any of a V region being rich in lattice vacancy, an OSF region and an I region being rich in interstitial silicon, and secures the improvement of electric characteristics such as oxide film breakdown voltage, which results in the manufacture, at a low cost, of a silicon single crystal wafer having no defects and exhibiting a high breakdown voltage and excellent electrical characteristics.

Description

Description Silicon silicon single crystal manufacturing method and silicon single crystal

The present invention is directed to a defect-free area having no defects in any of the V area, the I area, and the OSF area as described later, and having no defects detected from the u deposition. The present invention relates to a method for producing a silicon single crystal at high speed and in a stable manner. Background art

In recent years, with the miniaturization of elements due to the high integration of semiconductor circuits, silicon single crystals manufactured by the Czochralski method (CZ method), which is the substrate, have been developed. Quality requirements are increasing. In particular, single crystal growth-induced defects, such as Grown-in defects such as FPDs, LSTDs, and COPs, that degrade oxide film breakdown voltage characteristics and device characteristics, are present and their density is high. And reduction of size are emphasized.

In describing these defects, first, they are called vacancies (hereinafter sometimes abbreviated as “V”) incorporated into silicon single crystals. Void-type point defects and interstitial type called interstitials-silicon (Interstitia 1-Si, hereinafter sometimes abbreviated as "I") We explain what is generally known about the factors that determine the incorporated concentration of each of the silicon point defects.

In a silicon single crystal, the V region is a region where there are many Vacancy, that is, recesses and holes generated due to lack of silicon atoms, and the I region. This is a region where dislocations and extra silicon atom lumps are generated due to the presence of extra silicon atoms. Ma In addition, between the V region and the I region, there is a Neutran 1 (Neutra 1; hereafter, sometimes abbreviated as N) region with no (small) lack or excess of atoms. It will be. The above-mentioned green-in defect (FPD, LSTD, COP, etc.) is the result of point defects agglomerating when V and I are over-saturated. It can be seen that point defects do not aggregate and do not exist as the above-mentioned glow-in defects, even if there is some deviation of atoms, even if there is a certain degree of saturation, if they are less than saturation. I came.

The concentration of these two point defects is determined by the relationship between the crystal pulling rate (growth rate) in the CZ method and the temperature gradient G near the solid-liquid interface in the crystal, and the boundary between the V region and the I region is determined. In the vicinity, a defect called OSF (Oxidation Induced Stacking Fault) is ring-shaped when viewed in a cross section perpendicular to the crystal growth axis. It has been confirmed that it is possible to use it for a long time.

These defects caused by crystal growth are caused by the growth rate in the crystal axis direction by a CZ pulling machine using an in-furnace structure (hot zone: HZ) with a large temperature gradient G near the solid-liquid interface in ordinary crystals. When the speed is changed from a high speed to a low speed, a defect distribution diagram as shown in Fig. 6 is obtained.

When these defects caused by crystal growth are classified, for example, when the growth rate is relatively high, for example, about 0.6 mm / min or more, voids formed by vacancy-type point defects are gathered. Glowin defects such as FPD, LSTD, and COP exist at high density throughout the crystal diameter direction, and the region where these defects exist is called the V region (see Fig. 6). (A)). When the growth rate is 0.6 mm Z min or less, the OSF ring is generated from the periphery of the crystal due to the decrease in the growth rate, and the interstitial silicon is formed outside the ring. Defects (Large Dislocations: LDSD, LSEPD, LFPD, etc.) defects (Large Dislocation Clusters) which are considered to be caused by dislocation loops The area where these are present at low density and these defects are present is called the I area (sometimes called the LZD area). Furthermore, when the growth rate is reduced to about 0.4 mm / min or less, the OSF ring shrinks to the center of the wafer and disappears, and the entire surface becomes the I region (see the line in FIG. 6). (C)) ₀

In recent years, outside the OSF ring between the V region and I region, outside the OSF ring, there are also FPDs, LSTDs, and COPs caused by vacancies, called L regions, and LSEPDs and LFPDs caused by interstitial silicon. The existence of an area that does not exist has been discovered. This region is outside the OSF ring, and when oxygen precipitation heat treatment is performed and the contrast of deposition is confirmed by X-ray observation or the like, oxygen precipitation is almost eliminated. It has been reported that it is on the side of the I region that is not rich enough to form LSEPD and LFPD (line (B) in Fig. 6).

In the usual method, these N regions exist obliquely with respect to the growth axis direction when the growth rate is reduced, so that only a part of the N region exists in the aeah plane (see, for example, FIG. 6). Line (B), outside the OSF ring (only around the aeha).

For this N region, the Boronkov theory (V.V.V oronkov; Journal rystal G rowth, 59 (1992) 625-643) raises It is proposed that the VZG, a ratio of the velocity (V) and the temperature gradient (G) in the crystal-liquid interface axis direction, determines the total concentration of point defects. Considering this fact, since the pulling rate (growth rate) should be almost constant in the plane, G has a distribution in the plane. At the raising speed, a force was obtained that could only obtain a crystal whose center was in the V region, sandwiched the N region, and became the I region in the periphery.

Therefore, recently, the distribution of G in the plane was improved, and the N region, which existed only at an angle, was pulled up, for example, while gradually lowering the pulling rate (growth rate). At a certain pulling speed, it became possible to produce crystals in which the N region spread over the entire horizontal surface (the entire surface of the wafer). In addition, in order to enlarge the crystal in the entire N region in the length direction, it can be achieved to some extent by pulling up while maintaining the pulling speed when the N region spreads laterally. Also, taking into account that G changes as the crystal grows, and correcting for it, adjusting the pulling speed so that V / G remains constant, the growth direction will be more In addition, the crystal in the entire N region can be expanded.

However, as described above, the entire surface is in the N region, and although it is a single crystal that does not generate an OSF ring when subjected to thermal oxidation and has no FPD or LZD on the entire surface. It was found that oxide film defects could occur significantly. This causes electrical characteristics such as oxide withstand voltage characteristics to deteriorate, and it is not sufficient to merely say that the entire surface of the conventional device is in the N region. Further improvement was desired.

Further, in order to pull up the crystal in the N region as described above, it is necessary to reduce the pulling speed lower than that of the conventional crystal in the V region. In addition, there is a problem that the productivity of the crystal is significantly reduced due to the narrow control range. In order to cope with the growing demand for semiconductors in recent years and low cost, it is also necessary to produce high-quality silicon single crystals at high speed and in a stable manner. Disclosure of the invention

Accordingly, the present invention provides a method for producing a silicon single crystal by the chiral scan method, in which a V region, an OSF region, and an interstitial silicon region of a vacancy rich are provided. High-speed and stable production of silicon single crystals that do not belong to any of the I regions of the switch and that can reliably improve electrical characteristics such as oxide withstand voltage. The objective is to provide a defect-free silicon single crystal wafer with excellent electrical properties at a low cost.

To achieve the above objective, according to the present invention, it is housed in a crucible. After the seed crystal is brought into contact with the silicon melt, the seed crystal is pulled up from a rotating force S to grow a silicon single crystal by the Chiocular key method. In the method for producing a silicon single crystal, the crucible is rotated without rotating or 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. The silicon is characterized by growing a crystal in an N region outside the OSF generated in the defect free region where there is no defect region detected by Cu deposition. A method for producing a single crystal is provided.

According to such a manufacturing method, when the grown crystal is used as a wafer, the entire region includes defects such as FPDs in the V region and giant dislocation clusters in the I region (LSEPD, LFPD). ) And N region where OSF defects are not formed, and there are no defects and no defects (Cu deposition defects) detected by Cu deposition. A silicon single crystal can be manufactured faster and more stably than before.

Further, according to the present invention, after the seed crystal is brought into contact with the silicon melt accommodated in the crucible, the seed crystal is pulled up while being rotated while rotating the silicon single crystal. In a method for producing a silicon single crystal by a chiral key method for growing a crystal, the crucible is rotated without being rotated or in the same direction as the rotation direction of the seed crystal. In addition, when the growth rate of the silicon single crystal during growth is gradually reduced, the defect area detected by the Cu deposition remaining after the OSF ring disappears disappears. The crystal growth is controlled by controlling the growth rate between the boundary growth rate and the growth rate at the boundary where interstitial dislocation loops occur when the growth rate is further reduced. A method for producing a silicon single crystal is also provided.

Even by such a method, V region defects such as FPD, I region defects such as giant dislocation clusters, and OSF defects are not formed, and Cu deposition defects also exist. Thus, it is possible to more reliably and stably produce a defect-free silicon single crystal that has no defect. When a silicon single crystal is produced by these methods, it is preferable to grow a silicon single crystal while applying a horizontal magnetic field to the silicon melt. .

In this way, by growing a silicon single crystal while applying a horizontal magnetic field to the silicon melt [], the convection of the melt is suppressed and the defect-free silicon is grown. A single crystal can be grown more stably.

Further, it is preferable that the rotation speed of the crucible is set in a range of 0 to 2 rpm.

In this way, without rotating the crucible (rotation speed: O 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, the silicon If a silicon single crystal is grown, a defect-free silicon single crystal can be grown at a higher speed.

A defect-free silicon single crystal wafer characterized by being sliced from silicon single crystal gas grown by the above method is provided. .

Such silicon wafers do not include V region defects such as FPDs, I region defects such as giant dislocation clusters, and OSF defects, and have a Cu deposition. It will be a defect-free silicon single crystal wafer with no defects, high breakdown voltage and excellent electrical characteristics, and will be inexpensive because it is grown at high speed.

Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto. Prior to the explanation, it is necessary to explain each of the above terms in advance.

1) FPD (Flow Pattern Defect) is a method in which a wafer is cut out from a silicon single crystal rod after growth, and the strained layer on the surface is etched with a mixed solution of hydrofluoric acid and nitric acid. After removal by etching, the surface is etched (Secco etching) with a mixture of K ₂ Cr ₂ O ₇ , hydrofluoric acid and water. Cuts and ripples occur. This ripples The higher the FPD density in the wafer surface, the more the oxide film withstand pressure increases (see Japanese Patent Application Laid-Open No. 1991-92445).

2) SEPD (Secco Etch Pit Defect) is a FPD that has a flow pattern when the same Secco etching as FPD is performed. The one without it is called SEPD. Among these, SEPD (LSEPD) with a size of 10 xm or more is considered to be caused by dislocation clusters.If a dislocation cluster exists in the device, the Leakage; leaks and no longer functions as a P-N junction. .

3) LSTD (Laser Scatting Tomography Defect) is a process in which a silicon monocrystal rod is cut out from a grown silicon single crystal rod, and the strained surface layer is mixed with hydrofluoric acid and nitric acid. After removal by etching with liquid, the wafer is cleaved. Infrared light is incident from this cleavage plane, and light emitted from the wafer surface is detected to detect scattered light due to defects existing in the wafer. And can be. Scatterers observed here have already been reported at academic meetings and are considered to be oxygen precipitates (Jpn. J. Appl. Phys. Vol. 32, P36). 79, 1993). Recent studies have also reported that it is an octahedral void.

4) COP (Crystal Originated Particulate 1e) is a defect that causes the oxide film breakdown voltage at the center of the wafer to deteriorate, and the defect that causes FPD in the Secco etch is SC-1 washing (washing with a mixture of NH ₄ OH: H ₂ O ₂ : H 2 O = 1: 1: 1: 10) works as a selective etching solution, and becomes COP. The diameter of this pit is less than 1 μm and is examined by the light scattering method.

5) L / D (Large D is 1 ocation) is an abbreviation of interstitial dislocation loop, which includes LSEPD and LFPD. These defects are thought to be caused by dislocation loops in which the aggregates aggregate. As mentioned above, LSEPD refers to those larger than 1 μππι among SEPDs. LFPD refers to the above-mentioned FPDs whose tip pits have a size of 1 O / xm or more, and this is also considered to be caused by a dislocation loop.

6) The Cu deposition method accurately measures the position of defects in semiconductor wafers, improves the detection limit for defects in semiconductor wafers, and accurately measures even finer defects. It can be analyzed.

A specific method of evaluating wafers is to form an oxide film of a predetermined thickness on the wafer surface, and to destroy the oxide film on a defect site formed near the wafer surface to obtain a defect. Electrode such as Cu is deposited (deposition) on the site. In other words, in the Cu deposition method, when a potential is applied to an oxide film formed on the wafer surface in a liquid in which Cu ions are dissolved, a current is supplied to a portion where the oxide film has deteriorated. This is an evaluation method that utilizes the fact that the flow and Cu ions are precipitated as Cu. It is known that defects such as COP exist in portions where the oxide film is easily deteriorated.

The defect site of the wafer that has been Cu deposited can be analyzed under the condensing light or directly with the naked eye to evaluate its distribution and density. Electron microscope (TEM) or scanning electron microscope (S

E M) can also be checked.

As described above, according to the present invention, a silicon single crystal in a defect-free region that does not include a V region, an OSF region, an I region, and a Cu deposition defect region is rapidly drawn. Can be raised. Therefore, silicon single crystals that can improve electrical characteristics such as oxide film breakdown voltage can be manufactured at high speed and in a stable manner, and defect-free silicon with high breakdown voltage and excellent electrical characteristics can be obtained. Can be provided at a low cost. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows an example of a silicon single crystal manufacturing apparatus that can be used in the present invention.

(a) Schematic diagram

(b) Direction of rotation of crystal and knowledge

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

Figure 3 is a graph showing the relationship between the crucible rotation speed and the defect-free region growth rate.

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

Figure 5 is a graph showing the relationship between crucible rotation speed and initial oxygen concentration.

(a) Crucible rotation speed for crystal 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 crystal defect distribution according to a conventional technique. BEST MODE FOR CARRYING OUT THE INVENTION

The present inventors have investigated in detail the vicinity of the boundary between the V region and the I region with respect to the silicon single crystal growth by the CZ method, and found that the OSF region is located between the V region and the I region. Outside the ring, a neutral N region was found in which the number of FPDs, LSTDs, and COPs was very small and L / D was absent.

However, even if the crystal was grown in the N region having no green-in defect, the oxide film withstand voltage characteristics were poor, and the cause was not well understood. Thus, the present inventors conducted a more detailed investigation on the N region by the Cu deposition method, and found that the N region outside the OSF region was used. Therefore, it is evident that some of the regions where oxygen precipitation is likely to occur after the precipitation heat treatment have regions where defects detected by the Cu deposition process are significantly generated. discovered. The inventors have also found that this causes deterioration of electrical characteristics such as oxide breakdown voltage characteristics.

Therefore, it is possible to expand the N-region outside the OSF, which is free of defect regions detected by Cu deposition, over the entire area of the wafer. If possible, the above-mentioned various green defects are not present and the oxide film withstand voltage characteristics can be surely improved. And

Then, the growth rate of the N region outside the OSF, where the Cu depossion defect region disappears, and the growth speed of the I region where the giant dislocation cluster appears. By growing a single crystal at a rate between the above (hereinafter, sometimes referred to as a defect-free area growth rate), it is possible to eliminate the various types of green-in defects. In addition, it was found that a defect-free silicon single-crystal silicon wafer capable of reliably improving the oxide film breakdown voltage characteristics and the like was obtained.

However, the growth rate of such a defect-free region needs to be lower than the conventional single crystal pulling rate, and the control range is narrow. Let's raise the cost of single crystal production. Therefore, it is necessary to improve the growth rate of the defect-free region.

Thus, 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 that the rotation of the crucible or seeding was not performed. It has been found that by rotating the crystal in the same direction as that of the crystal, the growth rate of the defect-free region can be increased.

The present invention has been completed on the basis of these findings, that is, without rotating the crucible or in the same direction as the rotation direction of the seed crystal. The N region outside the OSF, which is formed in a ring shape when subjected to thermal oxidation treatment when it is converted, and is detected by the Cu deposition. The feature is to grow a crystal in a defect-free region where no defect region exists. It is a thing.

Hereinafter, the present invention will be described in more detail with reference to the drawings, but the present invention is not limited thereto.

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

The Norrebo 32 has a quartz crucible on the inner side for containing the silicon melt (hot water) 2 and a graphite crucible on the outer side. Further, a positive / negative rotation switching switch is provided so that the crucible holding shaft 33 can be rotated in either the left or right direction by a rotating mechanism. As shown in FIG. 1 (b), the crucible 32 is moved. The seed crystal can be rotated in the same direction as the rotation direction (upper axis 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 an annular outer periphery is provided around the solid-liquid interface 4 of the crystal. Insulation 10 is provided. The outer heat insulating material 10 is provided with an interval of 2 to 20 cm between its lower end and the molten metal surface 3 of the silicon melt 2. Further, a cylindrical cooling device for spraying a cooling gas or cooling a single crystal by blocking radiant heat may be provided.

By doing so, the difference between the temperature gradient G c [° C / cm] at the center of the crystal and the temperature gradient G e at the periphery of the crystal becomes smaller. For example, the temperature gradient around the crystal is greater than the crystal center. It is also possible to control the furnace temperature to lower the temperature.

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

In order to produce a silicon single crystal using such a single crystal pulling apparatus 30, first, a high-purity polycrystalline silicon raw material is melted in a crucible 32 at a melting point (about 142 0 ° C) Heat to above and melt. Next, by unwinding the wire 7, the tip of the seed crystal is brought into contact with or immersed substantially in the center of the surface of the melt 2. Thereafter, the crucible holding shaft 33 is rotated, and the wire 7 is wound while being rotated. As a result, the seed crystal is pulled while rotating, and the growth of the single crystal is started. Thereafter, by adjusting the pulling speed and the temperature appropriately, a substantially cylindrical single crystal rod 1 can be obtained. It can be.

At this time, the rotation direction of the seed crystal, that is, the rotation direction of the crucible and the rotation direction of the crucible are conventionally set to be opposite to each other, but in the present invention, when growing the silicon single crystal as described above, When the crucible is rotated without rotating or in the same direction as the rotation of the seed crystal, the N region outside the OSF, which is generated in a ring when the thermal oxidation treatment is performed, is performed. Therefore, the crystal is grown in a defect-free region where no defect region is detected by the Cu deposition.

(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 single crystal manufacturing apparatus 30 as described above, an experiment was performed to gradually reduce the crystal growth rate as follows. The FPD, LFPD, LSEPD, and OSF of the obtained single crystal were confirmed, and the withstand voltage characteristics of the oxide film were evaluated.

First, a 250-cm (600 mm) diameter quartz crucible was charged with 150 kg of polycrystalline silicon as a raw material, and an 8-inch (200 mm) diameter was used. ), A silicon single crystal of orientation <100> was grown. Here, when growing a single crystal, the growth rate was controlled so that the growth rate gradually decreased from 0.8 mm / min force to 0.4 mm / miίι from the straight body of 10 cm to the tail. did.

Such an experiment of gradually decreasing the crystal growth rate was performed by setting the crucible to various rotation speeds. Specifically, the crucible is kept stopped (0 rpm), or in the same direction as the seed crystal rotation direction (upper shaft rotation direction), 0.1 rpm, 0.3 rpm, 0.5 rpm. rpm, 1.0 rpm, 2.0 rpm, 3.0 rpm, and 0.1 rpm, 1.0 rpm, 2.0 rpm in the opposite direction to the seed crystal. Set to a number. In each case, during the growth of the single crystal, a horizontal magnetic field was applied by a superconducting method so that the magnetic field strength at the center of the single crystal was 400 G. The magnetic field strength is not particularly limited. For example, it is appropriate to apply a horizontal magnetic field having a center magnetic field strength of about 500 to 500 G.

Each silicon single crystal grown as described above was evaluated as follows. Evaluation method

(1) After cutting the straight body of each grown single crystal rod into blocks with a length of 10 cm in the crystal axis direction, each block is further divided vertically in the crystal axis direction. The sample was cut to a thickness of about 2 mm.

(2) FPD, LFPD, LSEPD, and OSF of the above sample were confirmed. Specifically, after grinding each sample, it was subjected to milling and seco-etching (30 minutes), and was left unstirred. After the specified treatment, the density of each defect was measured.

For the OSF evaluation, heat treatment was performed at 115 ° C for 100 minutes (under a wet oxygen atmosphere), and then the system was cooled (put in and out at 800 ° C). After removing the oxide film with the solution, the OSF ring pattern was checked and the density was measured.

(3) Defect evaluation was also performed using Cu deposition. The processing method was such that one of the samples cut vertically in the crystal axis direction was cut into a 6-inch diameter ゥ -a-shape with a punching force D, and was polished to a mirror-like surface by polish. After the formation, Cu deposition treatment was performed to check the distribution of oxide film defects. At that time, the evaluation conditions are as follows.

Oxide film: 25 nm

Electric field strength: SMV / cm

Electric ffi application time: 5 minutes. Evaluation result

According to the above evaluation, in each silicon single crystal, the Cu deposition was applied to the N region outside the OSF, which was generated in a ring shape during thermal oxidation treatment. A defect-free area where no defective area was detected was confirmed. Figure 2 shows the relationship between such a defect-free region and its growth rate. From this figure, when the growth rate of the silicon single crystal during growth is gradually reduced, the defect area detected by the Cu deposition remaining after the OSF ring disappears disappears. The N region outside the OSF is between the boundary growth rate and the boundary growth rate at which the interstitial dislocation loop (giant dislocation cluster: I region) occurs when the growth rate is further reduced. Thus, it can be specified as a growth rate (a defect-free area growth rate) that is a defect-free area where no defect area detected by the Cu deposition exists.

The defect-free region growth rate was determined for each silicon single crystal as described above, and is shown in Table 1. In addition, in Fig. 3, the relationship between the crucible rotation speed and the defect-free region growth rate is graphed. The growth rate of the defect-free region shown in Table 1 and Fig. 3 is the same as that of the Cu deposition defect disappearance rate. Intermediate value with the dislocation cluster (LSEPD, LFPD) generation speed

<Table 1> Rotation speed of Norrevo Rotation speed (rpm) Growth rate of defect-free region

(mm / m 1 n)

2 .0 0 .5 3 5

Χ. 1 ~ [HI

-C TO IHJ ¾S Λ リ, ri o 丄

0 .1 0 .5 6 6 Stop rotation of the crucible 0 .0 0 .6 0 2

0. 1 0 .6 0 5

0. 3 0 .6 0 0

Upper shaft rotation direction 0.5 0 .5 9 4

1 .0 0 .5 8 5

2.0 0 .5 7 8

3 .0 0 .5 7 0

As can be clearly seen from FIGS. 1 and 3, when the Norrebo is rotated in the opposite direction to the seed crystal, the growth rate of the defect-free region increases as the rotation speed decreases. In any case, it will be less than 0.57 mm / min. On the other hand, when the crucible is stopped, or when the crucible is rotated in the same direction as the seed crystal to grow the crystal, the crystal growth rate is 0.57 mm / min or more. Depressed area growth rate has been achieved. Therefore, for example, by rotating the crucible without rotating or rotating the crucible in the same direction as the rotation direction of the seed crystal at a rotation speed in the range of 0 to 2 rpm, at least 0. o It is possible to achieve a defect-free area growth rate close to 8 mm / m1n, especially if it is 0 to 1 Pm, it will be 0.585 mm / m1n or more. A high defect-free region growth rate can be achieved.

From an experiment like this, using a device like the one in Fig. 1

-When producing silicon single crystals by the method, when the crucible is rotated without rotating or in the same direction as the seed crystal, and when the thermal oxidation treatment is performed. N-region outside the ring-shaped OSF In the defect-free region where there is no defect region detected by Cu deposition, in other words, when the growth rate of the growing silicon single crystal is gradually reduced, it remains after the OSF ring disappears. Between the growth rate of the boundary where the defect region detected by the Cu deposition disappears and the growth rate of the boundary where interstitial dislocation loops occur when the growth rate is gradually reduced. By growing the crystal at a controlled growth rate, it is possible to grow a silicon single crystal in which the entire crystal is a defect-free region at a high speed. In particular, when the crucible is rotated in the same direction as the seed crystal, preferably at a rotational speed in the range of 0 to 2 rpm, and more preferably in the range of 0 to l rpm, the defect-free silicon is obtained. A single crystal can be grown at a higher speed. Therefore, by slicing a silicon single crystal rod grown by such a method, the entire surface is free from defects, that is, V region defects such as FPD, and giant dislocations. High-quality silicon with high withstand voltage and excellent electrical characteristics that does not include I-region defects such as clusters, OSF defects, and no defects detected by Cu deposition. It is possible to obtain efficiently.

(Experiment 2): Relationship between crucible rotation and crystal-solid interface temperature gradient In order to grow a crystal that becomes an entire N region in the growth direction, V / G must be at least as described above. Adjust the pulling speed so that it is constant. Therefore, if G (the tangent (differential value) of the crystal temperature curve on the solid-liquid interface) can be increased, the pulling speed V also increases (V / G is constant), and the entire surface becomes an N region. Crystal can be grown.

Therefore, in order to verify the results obtained in Experiment 1, the relationship between the rotation of the crucible and the temperature gradient (G) in the direction of the crystal-solid interface at the crystal solid-liquid interface (G) was investigated using the comprehensive heat transfer analysis software “IHTCMJ (detailed description). Are described in TAKinney, DEBornside, RABrown and KMKim, Journal of Crystal Growth, vo 1.126, pp 413, (1993) and TAKinney and RABrown, Journal of Crystal Growth, vol. 132, pp551, (1993)), a convective simulation calculation was performed, and the axial temperature gradient (G) at the crystal-solid interface was investigated. Figure 4 shows the results.

Fig. 4 As is clear from FIG. 4, the crucible should be rotated more than when the crucible is rotated in the direction opposite to the rotation direction of the seed crystal (the direction of rotation of the upper shaft). Rotating in the same direction (upper shaft rotation direction) increases the temperature gradient G in the crystal-solid interface axial direction.

From the results of the simulation described above, G can be increased by rotating the crucible without rotating or rotating the crucible in the same direction as the rotation of the seed crystal. It is thought that the defect-free region growth rate V when growing a defective silicon single crystal can be increased. In other words, it supported 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. Thus, the crucible is rotated in the same direction as the seed crystal, and the crystal straight body is grown while gradually increasing the crucible rotation speed, and the straight body of the obtained silicon single crystal is obtained. The initial oxygen concentration was measured every 2 O cm. Figure 5 shows the results. As is evident from this graph, the oxygen concentration in the first part of the straight body grown with little rotation of the crucible was reduced, and the oxygen concentration in the latter half of the straight body was increased. As a result, the oxygen concentration in the entire single crystal rod can be kept almost constant. In addition, for example, when the target oxygen concentration is lower, if the crucible is stopped and grown under conditions close to (0 rpm), a defect-free and low oxygen concentration of silicon alone can be obtained. It can grow crystals. Note that the present invention is not limited to the above embodiment. The above The embodiment is an exemplification, and any of those having substantially the same configuration as the technical idea described in the claims of the present invention and having the same function and effect will be described. Even so, they are included in the technical scope of the present invention. For example, the apparatus used for producing a silicon single crystal according to the present invention is not limited to the apparatus as shown in FIG. 1, and the crucible is formed in the same direction as the seed crystal. It can be rotated, and it is a ring-shaped N region outside the OSF that occurs during thermal oxidation, and there is no defect region detected by Cu deposition. Any device that can produce a silicon single crystal in a defect region can be used without limitation. For example, crystal growth may be performed without applying a horizontal magnetic field.

Claims

The scope of the claims

1. After the seed crystal is brought into contact with the silicon melt contained in the knollerbo, it is pulled up while rotating the seed crystal to grow a silicon single crystal. In the method for manufacturing a silicon single crystal by the Larsky method, when the crucible is rotated without rotating or in the same direction as the rotation direction of the seed crystal and the thermal oxidation treatment is performed. The crystal is grown in the N-region outside the ring-shaped OSF, which has no defect region detected by Cu deposition. A method for producing silicon single crystals.

2. After the seed crystal is brought into contact with the silicon melt contained in the crucible, it is pulled up while rotating the seed crystal to grow a silicon single crystal. In the method for producing a silicon single crystal according to the silicon method, the crucible is rotated without rotating or in the same direction as the rotation direction of the seed crystal. When the growth rate of the 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 is further reduced. A method for producing a silicon single crystal, characterized in that a crystal is grown by controlling a growth rate between a growth rate of a boundary where an interstitial dislocation loop is generated and a growth rate of a boundary.

3. The silicon according to claim 1 or 2, wherein the silicon single crystal is grown while applying a horizontal magnetic field II to the silicon melt. Method for producing single crystal.

4. The silicon according to any one of claims 1 to 3, wherein the rotation speed of the crucible is in a range of 0 to 2 rpm. Method for producing single crystal.

5. It is characterized by being sliced from silicon single crystal force grown by the method according to any one of claims 1 to 4. Defect-free silicon single crystal ゥ wafer.