JPH0741391A - Silicon single crystal, heat treatment method thereof and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention is directed to the Czochralski method (hereinafter referred to as CZ
It is an object of the present invention to provide a silicon single crystal capable of forming a good surface-defect-free layer, a heat treatment method thereof, and a manufacturing method thereof. In order to achieve the above object, in the present invention,
The silicon single crystal manufactured by the CZ method is 1200 ° C-
Heat treatment at a high temperature of 1400 ° C, followed by 500 ° C-80
Heat treatment is performed in the temperature range of 0 ° C. In addition, in the process of manufacturing a silicon single crystal by the CZ method,
The same effect can be obtained by allowing the temperature range of 00 ° C to 500 ° C to stay for 200 minutes or more. A good defect-free layer is formed on the surface of the silicon wafer after the heat treatment for forming a defect-free layer on the silicon wafer obtained by this method and the silicon wafer cut out from the silicon single crystal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a density of 1 × 10 ⁵ cm ³ or less of fine crystal defects having a diameter of 1000 Å or more in a region within 5 μm from the surface of a silicon wafer after heat treatment for forming a defect-free layer. The present invention relates to a silicon single crystal produced by the Czochralski method (hereinafter, CZ method) in which a good surface-defect-free layer that does not exist can be easily formed, a heat treatment method thereof, and a production method thereof.

[0002]

2. Description of the Related Art A silicon single crystal manufactured by the CZ method contains fine crystal defects. Further, a silicon single crystal manufactured by the CZ method contains supersaturated oxygen. Supersaturated oxygen precipitates with the minute crystal defects as a generation center during the heat treatment in the LSI manufacturing process, generates an oxygen precipitation portion, and further induces giant secondary crystal defects such as dislocation loops and stacking faults. If these precipitates or secondary defects are introduced into the element formation region on the outermost surface of the silicon wafer, characteristic deterioration such as junction leakage is caused, which adversely affects the element. Therefore, in order to manufacture an LSI with a high yield, it is important to eliminate the fine crystal defects, which are the generation centers of oxygen precipitates, from the element formation region on the outermost surface of the silicon wafer and form a good surface-defect-free layer. is there.

As a heat treatment for the purpose of investigating the superiority or inferiority of the surface defect-free layer, a mixed atmosphere of nitrogen and oxygen was used.
In addition to 00 ° C. for 10 hours, a multi-step heat treatment (hereinafter, heat treatment for forming a defect-free layer) is generally performed at 650 ° C. for 16 hours in a nitrogen atmosphere, and at 1000 ° C. for 16 hours in a dry oxygen atmosphere. Further, the infrared tomography method is generally used for investigating microcrystalline defects on the outermost surface of a silicon wafer.

When a heat treatment for forming a defect-free layer is performed on a silicon wafer manufactured in the prior art, the density of fine crystal defects having a diameter of 1000 Å or more is 1 × 10 ⁶ / cm ³ or more on the outermost surface of the silicon wafer. It was not possible to eliminate the microcrystalline defects that exist at a density and are harmful to the device characteristics.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention provides a silicon single crystal manufactured by the CZ method capable of forming a good surface-defect-free layer, and a silicon single crystal for obtaining such characteristics. It is an object to provide a heat treatment method and a manufacturing method.

[0006]

In order to achieve the above object, in the present invention, a silicon single crystal produced by the CZ method is heat-treated at a high temperature of 1200 ° C to 1400 ° C, and then 500 ° C to 800 ° C. Heat treatment is performed in the temperature range. Preferably, after heat treatment at a high temperature of 1200 ° C to 1400 ° C, the temperature is continuously lowered to 400 ° C or lower and then 500
Heat treatment is performed in the temperature range of ℃ to 800 ℃. More preferably, after heat treatment at a high temperature of 1200 ° C to 1400 ° C, 1
Temperature range of 200 ℃ ~ 800 ℃ 0.1 ℃ / min ~ 100 ℃
It is cooled at a rate of / min, and heat treatment is continuously performed in a temperature range of 500 ° C to 800 ° C without lowering the temperature to 400 ° C or lower.
The heat treatment time at 1200 ° C. to 1400 ° C. high temperature is effective for 10 minutes or longer, but is preferably 30 minutes or longer.
The heat treatment time in the temperature range of 500 ° C to 800 ° C is 1
Although the effect can be seen even at 0 minutes, it is preferably at least 30 minutes. The silicon single crystal may be a wafer, an ingot, or a block.

Further, in the process of manufacturing a silicon single crystal by the CZ method, the temperature is 800 ° C. to 500 ° C. in a crystal manufacturing furnace.
The same effect can be obtained by allowing the temperature range of 2 to stay for 200 minutes or longer. Preferably, it is passed through a temperature range of 1200 ° C to 800 ° C for a residence time of 300 minutes or less, and 800 ° C.
The effect is further enhanced by allowing the temperature range of 500 ° C. to stay for 200 minutes or more.

The silicon wafer obtained by this method and the silicon wafer cut out from the silicon single crystal are
Regardless of the concentration of dissolved oxygen, the density of microcrystalline defects with a diameter of 1000 angstroms or more existing within a depth of 5 μm from the surface of the silicon wafer after the heat treatment for forming a defect-free layer is 1 × 10 ⁵ / Cm ³ or less, and a good defect-free layer is formed.

[0009]

In the process of growing a silicon single crystal by the CZ method, the diameter is about 2 in the high temperature range from the melting point to 1200 ° C.
Fine crystal defects of 00 to 800 angstrom are generated at a high density (about 10 ⁹ defects / cm ³ ). 1200 ° C ~ 8
In the temperature range of 00 ° C., relatively large ones of these microcrystalline defects grow and small ones decompose, resulting in low density of microcrystalline defects with a diameter of 1000 Å or more (about 10 ⁷ / cm ^3). ) Remains. 800 ℃ ~ 5
In the temperature range of 00 ° C., fine crystal defects with a diameter of about 300 Å are newly formed at a high density (about 10 ⁹ / cm ³ ), while fine crystal defects with a diameter of 1000 Å or more are about 100 μm. Dissolve to 300 Å. In the temperature range of 500 ° C. or lower, different kinds of defects called thermal donors occur.
Therefore, by performing heat treatment in a low temperature range of 500 ° C. to 800 ° C., it is possible to uniformly form fine crystal defects having a small size of about 300 Å at a high density.

If the diameter of the microcrystalline defects is 1000 angstroms or less, or if the defect density of 1000 angstroms or more is 1 × 10 ⁵ / cm ³ or less, the microcrystalline defects are present in the device active region on the outermost surface of the wafer. Even if it exists, it does not adversely affect the device characteristics. In addition, since the device active area of most devices is within 5 μm from the wafer surface, the defect-free layer is 5 μm from the surface.
It is sufficient to form up to the depth of. Therefore, a good surface-defect-free layer is a case where there are 1 × 10 ⁵ fine crystal defects having a diameter of 1000 Å or more and existing in a region having a depth of 5 μm from the surface of 1 × 10 ⁵ pieces / cm ³ or less.

In the heat treatment for forming a defect-free layer, the step of 1100 ° C. for 10 hours in a mixed atmosphere of nitrogen and oxygen increases the diffusion rate of the elements forming the microcrystalline defects and forms the microcrystalline defects. The purpose is to decompose the microcrystalline defects on the outermost surface of the silicon wafer by lowering the concentration of existing elements by utilizing the outward diffusion to the surface.

Since the CZ silicon single crystal produced by the usual method has a short residence time in the temperature range of 800 ° C. to 500 ° C., the diameter formed at 1200 ° C. to 800 ° C. is 1000.
It is not possible to dissolve microcrystalline defects of angstrom or more to about 300 angstrom. Therefore, even if the heat treatment for forming a defect-free layer is performed, the density of fine crystal defects having a diameter of 1000 Å or more and existing within a depth of 5 μm from the surface remains 10 ⁶ / cm ³ or more,
It was a factor that deteriorated the device characteristics.

On the other hand, when a normal silicon single crystal in the as-grown state is maintained at a high temperature of 1200 ° C. or higher to dissolve fine crystal defects, and then heat treatment is performed in a temperature range of 500 ° C. to 800 ° C. Since fine crystal defects having a small size of about 300 angstroms are uniformly formed at a high density, a good surface-defect-free layer can be formed. Further, by growing the oxygen precipitates by utilizing fine crystal defects which are uniformly present inside the crystal at a high density, it is possible to provide the characteristic excellent in intrinsic gettering ability. However, heat treatment at a temperature exceeding 1400 ° C. is dangerous because it is just below the melting point, and is not suitable as a manufacturing technique. At this time, after maintaining at a high temperature of 1200 ° C. or higher, 5
When the heat treatment is performed in the temperature range of 00 ° C. to 800 ° C., the influence of the thermal donor is eliminated, and thus it is possible to form a better surface-defect-free layer. Furthermore, after maintaining at a high temperature of 1200 ° C. or higher, the temperature range of 1200 ° C. to 800 ° C. is rapidly cooled at a rate of 0.1 ° C./min or higher, and the temperature of 500 ° C. to 800 ° C. continues without being lowered to 400 ° C. or lower. If the heat treatment is performed in the region, the growth of fine crystal defects can be completely suppressed, and a better surface-defect-free layer can be formed. However, the cooling rate in the temperature range of 1200 ° C to 800 ° C is 100 ° C /
If it exceeds the minute, different kinds of defects called rapid freezing defects are formed at high density, so the cooling rate must be 100 ° C./min or less.

The effect of this series of heat treatments is greatest when the silicon single crystal is a wafer, but even if it is an ingot or block, it has a sufficient effect.

In the process of producing a silicon single crystal by the CZ method, the same effect can be obtained by making the temperature range of 800 ° C. to 500 ° C. stay in the crystal producing apparatus for 200 minutes or more. In this case, when passing through a temperature range of 1200 ° C. to 800 ° C. for a staying time of 300 minutes or less, the growth of fine crystal defects is suppressed and the effect is further enhanced.

[0016]

EXAMPLES Examples of the present invention will be described below.
It goes without saying that the invention is not limited by the description of these examples. An infrared tomography method was used to measure the fine crystal defects on the outermost surface. The infrared tomography method is a method in which a crystal is irradiated with a YAG laser and light scattered by defects in the wafer is detected by a Si vidicon, and the diameter and density of microcrystalline defects can be measured with high sensitivity. In addition, all the densities shown here are densities of fine crystal defects having a diameter of 1000 angstroms or more. The presence of defects having a size smaller than that does not adversely affect the device characteristics, so the description thereof is omitted.

Example 1 A silicon block used as a heat treatment effect sample at 500 ° C. to 800 ° C. is as follows. Conduction type: p type (boron doped) Crystal size: 100 × 100 × 100 mm Resistivity: 10Ω. cm Oxygen concentration: 9.0 to 9.2 × 10 ¹⁷ atoms / cc (calculated using the oxygen concentration conversion coefficient by the Japan Electronic Industry Development Association) Carbon concentration: <1.0 × 10 ¹⁷ atoms / cc Calculation was carried out using a carbon concentration conversion coefficient by the Promotion Association) A plurality of these blocks were prepared, and each of them was subjected to the following heat treatment of the present invention. Heat treatment temperature: 1350 ° C. Heat treatment time: 120 minutes Heat treatment atmosphere: After heat treatment under the conditions of Ar, the temperature is lowered to 400 ° C. or lower, followed by heat treatment temperature: 650 ° C. Heat treatment time: 10 minutes, 30 minutes, 100 minutes, 400 minutes Heat treatment atmosphere: Heat treatment was performed under the condition of Ar 2.

Wafers were cut out from these blocks and subjected to the following heat treatment as a heat treatment for forming a surface-defect-free layer. Heat treatment temperature: 1100 ° C Heat treatment time: 10 hours Heat treatment atmosphere: After heat treatment under the conditions of N ₂ + O ₂ , the temperature is lowered to room temperature, and subsequently heat treatment temperature: 650 ° C heat treatment time: 16 hours Heat treatment atmosphere: N ₂ After heat treatment, the temperature was lowered to room temperature. Further, heat treatment was performed under the conditions of heat treatment temperature: 1000 ° C., heat treatment time: 16 hours, heat treatment atmosphere: dry O ₂ . In these cases, the density of fine crystal defects within 5 μm from the wafer surface was measured and shown in Table 1. The results in Table 1 indicate that the density of these fine crystal defects is 1 × 10 ⁵ defects / cm ³ or less, and that the wafer cut from the silicon block subjected to the heat treatment of the present invention forms a good surface-defect-free layer. It is shown that.
Further, the longer the heat treatment time, the higher the effect.

Example 2 Effect of heat treatment on sample shape The following silicon single crystals were prepared as samples having different shapes. (1) Silicon wafer The silicon wafer used is as follows. Conductive type: p-type (boron-doped) Crystal diameter (wafer diameter): 6 inches (150 mm) Resistivity: 10 Ω · cm Oxygen concentration: 7.3 to 7.5 × 10 ¹⁷ atoms / cc (oxygen by Japan Electronic Industry Development Association) Calculation using concentration conversion coefficient) Carbon concentration: <1.0 × 10 ¹⁷ atoms / cc (Calculation using carbon concentration conversion coefficient by Japan Electronic Industry Development Association) Thickness of wafer subjected to heat treatment: 0.625 (mm) (2) Silicon Block The silicon block of Example 1 was used. (3) Silicon ingot The silicon ingot used is as follows. Conductive type: n-type (P-doped) Crystal diameter: for 6 inches (160 mm) Resistivity: 10 Ω · cm Oxygen concentration: 9.8 to 10.0 × 10 ¹⁷ atoms / cc (oxygen concentration conversion by Japan Electronic Industry Development Association) Carbon concentration: <1.0 × 10 ¹⁷ atoms / cc (Calculated using the carbon concentration conversion coefficient by Japan Electronic Industry Development Association) Ingot straight body length: 1500 (mm) These wafers or blocks Alternatively, a plurality of ingots were prepared and subjected to the following heat treatment of the present invention. (A) After the heat treatment, the temperature is lowered to 400 ° C. or less and then the heat treatment is performed.
Among the heat treatments (→) of the heat treatment (1) of the present invention for applying the heat treatment, the heat treatment in which the holding time at the low temperature heat treatment (650 ° C.) is 100 minutes. (B) After the heat treatment, the temperature is not lowered to 400 ° C. or lower and heat treatment is performed.
Heat treatment according to the present invention in which heat treatment is performed without quenching between the heat treatment temperature: 1350 ° C., heat treatment time: 120 minutes, heat treatment atmosphere: Ar, heat treatment is performed, and then cooling is performed at 0.05 ° C./min.
Heat treatment in which the temperature is not lowered to 400 ° C. or lower, and subsequently the heat treatment temperature is 650 ° C., the heat treatment time is 100 minutes, and the heat treatment atmosphere is Ar. (C) After the heat treatment, the temperature is not lowered to 400 ° C. or less and the heat treatment is performed.
Heat treatment according to the present invention, in which a heat treatment is performed by rapidly cooling between the heat treatment temperature: 1350 ° C., a heat treatment time: 120 minutes, a heat treatment atmosphere: Ar, heat treatment is performed at a temperature of 10 ° C./min, and then 40
Heat treatment temperature: 650 ° C. Heat treatment time: 100 minutes Heat treatment atmosphere: Ar heat treatment in which Ar is performed. These wafers, the wafers cut from the blocks, or the wafers cut from the ingot were subjected to the heat treatments and and in Example 1 as the heat treatment for forming the surface defect-free layer. In these cases, the density of fine crystal defects within 5 μm from the wafer surface was measured and is shown in Table 2. The results shown in Table 2 indicate that these microcrystal defect densities are all 1 × 10 ⁵ defects / cm ³ or less, and the silicon wafers subjected to the heat treatment of the present invention, the wafers cut from the blocks, and the ingots were cut out. The wafer is shown to form a good surface defect free layer.

Comparative Example 1 A silicon wafer cut by a CZ method, which was cut from an arbitrary portion from a seed crystal side to a liquid surface side of a silicon ingot, was subjected to the heat treatment step of Example 1 and was not performed.
The heat treatment step and and only were carried out to measure the fine crystal density of the outermost surface, which is shown in Table 1 together with Example 1.
From Table 1, these microcrystal defect densities are all 1 × 1.
It is 0 ⁵ pieces / cm ³ or more, which means that a good surface-defect-free layer is not obtained.

Comparative Example 2 The heat treatment temperature of the heat treatment step of Example 1 was set to 1 with respect to a silicon wafer cut from an arbitrary portion of the silicon ingot grown by the CZ method from the seed crystal side to the liquid surface side.
The heat treatment was performed under the condition of 190 ° C., followed by cooling at 10 ° C./min, and then the heat treatment was performed under the condition that the heat treatment time was 100 minutes without lowering the temperature to 400 ° C. or lower. These wafers were subjected to the heat treatment steps of Example 1 and and the fine crystal defect density of the outermost surface was measured. The results are shown in Table 1 together with Example 1. From Table 1, each of these fine crystal defect densities is 1 × 10 ⁵ defects / cm ³ or more,
It can be seen that a good surface-defect-free layer has not been obtained.

Comparative Example 3 A silicon wafer cut by a CZ method at a desired position from the seed crystal side to the liquid surface side of a silicon ingot was subjected to the heat treatment step of Example 1 and then 11
Cooling was performed at 0 ° C./min, and the temperature was not lowered to 400 ° C. or lower, and subsequently, heat treatment was performed under the condition that the heat treatment time of the heat treatment step was 100 minutes. These wafers are subjected to the heat treatment steps of Example 1 and and to measure the fine crystal density of the outermost surface,
The results are shown in Table 1 together with Example 1. From Table 1, it can be seen that the density of these fine crystal defects is 1 × 10 ⁵ defects / cm ³ or more, and no good surface defect-free layer is obtained.

Comparative Example 4 A silicon wafer cut by a CZ method from a desired position from the seed crystal side to the liquid surface side of a silicon ingot was subjected to the heat treatment step of Example 1 and then 10
The heat treatment was performed at a temperature of 820 ° C./min, without lowering the temperature to 400 ° C. or lower, and subsequently at a heat treatment temperature of 820 ° C. in the heat treatment step, and for a heat treatment time of 100 minutes. These wafers were subjected to the heat treatment steps of Example 1 and and the fine crystal density of the outermost surface was measured. The results are shown in Table 1 together with Example 1. From Table 1, it can be seen that the density of these fine crystal defects is 1 × 10 ⁵ defects / cm ³ or more, and no good surface defect-free layer is obtained.

Comparative Example 5 A silicon wafer cut by a CZ method at a desired position from the seed crystal side to the liquid surface side of a silicon ingot was subjected to the heat treatment in the heat treatment step of Example 1 and then at 10 ° C. The heat treatment was performed at a heat treatment temperature of 490 ° C. for 100 minutes without cooling to 400 ° C. or lower. These wafers were subjected to the heat treatment steps of Example 1 and and the fine crystal defect density of the outermost surface was measured. The results are shown in Table 1 together with Example 1. From Table 1, it can be seen that the density of these fine crystal defects is 1 × 10 ⁵ defects / cm ³ or more, and no good surface defect-free layer is obtained.

Example 3 In the process of growing a silicon single crystal
In the case of applying the present invention, the silicon single crystal production apparatus used in the present invention is usually C
The manufacturing apparatus is not particularly limited as long as it is used for manufacturing a silicon single crystal by the Z method, and the manufacturing apparatus shown in FIG. 1 was used in this example. This CZ method silicon single crystal manufacturing apparatus 1 includes a heating chamber 2a that houses a structure for melting silicon and a pulling chamber 2b that houses a grown silicon single crystal ingot S that is separated and connected by a separation mechanism 20. And a crucible 5 including a quartz crucible 5b and a graphite crucible 5a for protecting the quartz crucible 5b in the heating chamber 2a.
The heater 6 arranged so as to surround the side surface of the crucible 5, and the heat from the heater 6 heats the heating chamber 2a.
A heat insulating member 11 is arranged in order to prevent the crucible 5 from escaping to the outside. The crucible 5 is connected to a driving device (not shown) by a rotating jig 4, and is rotated at a predetermined speed by the driving device. The crucible 5 is moved up and down in order to compensate for the decrease of the silicon melt liquid level due to the decrease of the silicon melt in the crucible 5. In the pulling chamber 2b, a pulling wire 7 suspended in the chamber is installed, and a chuck 9 for holding a seed crystal 8 is provided at the lower end of this wire. An upper end side of the pulling wire 7 is provided with a pulling device which is wound around the wire winding machine 10 to pull up the silicon single crystal ingot. Then, in the chamber 2, the gas introduction port 12 formed in the pulling chamber 2b is formed.
Ar gas is introduced into the heating chamber 2a, and the Ar gas is evenly distributed in the heating chamber 2a and discharged from the gas outlet 13. The Ar gas is caused to flow out in this manner so that SiO generated in the chamber due to the melting of silicon is not mixed into the silicon melt. Using this apparatus, a silicon single crystal was grown under the following conditions. Raw material melt weight: 45 kg Crystal growth rate: 1.2 mm / min Crystal a: Without rapid cooling between high temperature and low temperature 1200 ° C. to 800 ° C. residence time in temperature range: 350 minutes 800 ° C. to 500 ° C. residence time in temperature range : 400 minutes Crystal b: When rapidly cooling between high temperature and low temperature 1200 ° C. to 800 ° C. staying time in temperature range: 120 minutes 800 ° C. to 500 ° C. staying time in temperature range: 400 minutes Silicon single crystal grown under these conditions The ingot is as follows. Crystal a conductivity type: p-type (boron-doped) Crystal diameter: for 6 inches (160 mm) Resistivity: 10 Ω · cm Oxygen concentration: 9.8 to 10.0 × 10 ¹⁷ atoms / cc (oxygen concentration by Japan Electronic Industry Development Association) Calculated using conversion coefficient) Carbon concentration: <1.0 × 10 ¹⁷ atoms / cc (Calculated using conversion coefficient of carbon concentration by Japan Electronic Industry Development Association) Crystal b Conductivity type: n-type (P-doped) Crystal diameter: For 6 inches (160 mm) Resistivity: 2 Ω · cm Oxygen concentration: 7.5 to 7.8 × 10 ¹⁷ atoms / cc (calculated using the oxygen concentration conversion coefficient by the Japan Electronic Industry Development Association) Carbon concentration: <1. 0 × 10 ¹⁷ atoms / cc (calculated by using the carbon concentration conversion coefficient by Japan Electronics Industry Promotion Association) Example 1 was applied to wafers cut from these ingots.
The heat treatment and the heat treatment performed in 1) were performed as the heat treatment for forming a defect-free surface layer. In these cases, the density of fine crystal defects within 5 μm from the wafer surface was measured and shown in Table 3. The results in Table 3 indicate that these microcrystal defect densities are all 1 × 10 ⁵ defects / cm ³ or less, and that the wafer cut from the ingot produced by the method of the present invention has a good surface defect-free layer. It shows that it forms.

Comparative Example 6 Using the apparatus used in Example 3, a silicon single crystal was grown under the following conditions. Raw material melt weight: 45 kg Crystal growth rate: 1.2 mm / min 1200 ° C. to 800 ° C. temperature range residence time: 200 minutes 800 ° C. to 500 ° C. temperature range residence time: 190 minutes Silicon single crystal grown under these conditions The ingot is as follows. Conductive type: p-type (boron-doped) Crystal diameter: for 6 inches (160 mm) Resistivity: 10 Ω · cm Oxygen concentration: 9.8 to 10.0 × 10 ¹⁷ atoms / cc (oxygen concentration conversion coefficient by Japan Electronic Industry Development Association) Carbon concentration: <1.0 × 10 ¹⁷ atoms / cc (calculated using the carbon concentration conversion coefficient by Japan Electronic Industry Development Association) Example 1 was applied to wafers cut from these ingots.
The heat treatment and the heat treatment performed in 1) were performed as the heat treatment for forming a defect-free surface layer. In these cases, the density of fine crystal defects within 5 μm from the wafer surface was measured and shown in Table 3. From Table 3, it can be seen that the density of these fine crystal defects is 1 × 10 ⁵ defects / cm ³ or more, and a good surface-defect-free layer is not obtained.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

Since the silicon single crystal of the present invention can form a good surface-defect-free layer, it has a high reliability of the device active layer and is suitable for a wafer for a MOS device.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a CZ method silicon single crystal manufacturing apparatus used in an example of the present invention.

[Explanation of symbols]

1 ... CZ method silicon single crystal manufacturing apparatus, 2 ... chamber,
2a ... Heating chamber, 2b ... Pulling chamber, 4 ... Rotating shaft, 5 ... Crucible, 5a ... Graphite crucible, 5b ... Quartz crucible, 6 ... Heating heater, 7 ... Wire, 9 ... Chuck, 10 ... Wire winding machine, 11 … Thermal insulation, 12
… Gas inlet, 13… Gas outlet, 2
0 ... Separation mechanism.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Tsuneo Nakatsune 3434 Shimada, Hikari City, Yamaguchi Prefecture Inside the Nippon Steel Works, Nippon Steel Corporation (72) Masamichi Okubo 3434 Shimada, Hikari City, Yamaguchi Prefecture Nittetsu Dentsu Child Co., Ltd.

Claims (8)

[Claims] 1. A silicon single crystal produced by the Czochralski method, which is first heat-treated at a high temperature of 1200 ° C. to 1400 ° C., and then heat-treated at a low temperature of 500 ° C. to 800 ° C. Heat treatment method. 2. A silicon single crystal produced by the Czochralski method is first subjected to a high temperature heat treatment at 1200 ° C. to 1400 ° C. and then subjected to a low temperature heat treatment at 500 ° C. to 800 ° C. without being lowered to 400 ° C. or lower. A method for heat treating a silicon single crystal characterized. 3. A silicon single crystal produced by the Czochralski method is first subjected to a high temperature heat treatment at 1200 ° C. to 1400 ° C., and then a temperature range of 1200 ° C. to 800 ° C. is adjusted to 0.
A method for heat treating a silicon single crystal, which comprises cooling at a rate of 1 ° C / min to 100 ° C / min, and subsequently performing a low temperature heat treatment at 500 ° C to 800 ° C without lowering the temperature to 400 ° C or lower. 4. The heat treatment method for a silicon single crystal according to claim 1, wherein the silicon single crystal is a silicon wafer. 5. The heat treatment method for a silicon single crystal according to claim 1, wherein the silicon single crystal is a silicon ingot or a block. 6. In the process of producing a silicon single crystal by the Czochralski method, the temperature is 800 ° C. in a crystal production furnace.
A method for producing a silicon single crystal, which comprises allowing a temperature range of 500 ° C. to stay for 200 minutes or more. 7. A process of producing a silicon single crystal by the Czochralski method, at 1200 ° C. in a crystal production furnace.
A method for producing a silicon single crystal, which is characterized in that a temperature range of -800 ° C is passed for a stay time of 300 minutes or less, and a temperature range of 800 ° C-500 ° C is allowed to stay for 200 minutes or more. 8. A silicon single crystal produced by the Czochralski method, which is obtained by adding a silicon wafer cut out from the silicon single crystal to a mixed atmosphere of nitrogen and oxygen at 1100 ° C. for 10 hours and at 650 ° C. in a nitrogen atmosphere. 16
5 μm deep from the surface of the silicon wafer after heat treatment at 1000 ° C. for 16 hours in a dry oxygen atmosphere
Silicon single crystal capable of forming a good surface-defect-free layer, characterized in that the density of microcrystalline defects having a diameter of 1000 angstroms or more and existing within m is 1 × 10 ⁵ defects / cm ³ or less. crystal.