JPH0741392A - Silicon single crystal and method for manufacturing the same - Google Patents

Abstract

(57) [Abstract] [Purpose] A silicon single crystal manufactured by the Czochralski method (hereinafter, CZ method), which is obtained by mirror-finishing a silicon wafer cut out from the silicon single crystal and further performing an ammonia-based cleaning. The present invention relates to a silicon single crystal in which generation of etch pits of 0.07 μm or more is suppressed when performed, and a manufacturing method thereof. [Structure] In the process of manufacturing a silicon single crystal by the CZ method, a temperature range of 1100 ° C to 850 ° C is passed in a crystal manufacturing furnace with a residence time of 250 minutes or less. Preferably, the temperature range from immediately after solidification to 850 ° C. in the furnace is 400
Pass with a stay time of less than a minute. Further, the silicon single crystal of the present invention, when the silicon wafer cut out from the silicon single crystal is mirror-finished and additionally subjected to ammonia cleaning, generation of etch pits of 0.07 μm or more was suppressed, It is a silicon single crystal with excellent quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon single crystal manufactured by the Czochralski method (hereinafter referred to as the CZ method), in which a silicon wafer cut out from the silicon single crystal is mirror-finished, and ammonia is added. The present invention relates to a silicon single crystal in which generation of etch pits of 0.07 μm or more is suppressed when a system cleaning is performed, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Solid solution oxygen is contained in a silicon single crystal produced by the CZ method. In addition, these solid solution oxygen precipitates in the process of manufacturing the silicon single crystal, and becomes fine oxygen precipitates. Further, minute secondary defects such as dislocation loops may occur from these minute oxygen precipitates in the process of manufacturing a silicon single crystal, although they are rare. If the minute secondary defects are present on the outermost surface of a silicon wafer that has been cut out from the silicon single crystal and subjected to mirror surface processing, an etch pit of 0.07 μm or more is formed during the subsequent ammonia-based cleaning. LSI on the etch pit
When such elements are formed, electric field concentration or the like occurs, which adversely affects the elements. Therefore, in order to manufacture an LSI with a high yield, a silicon single crystal in which generation of minute secondary defects that form etch pits during ammonia cleaning is suppressed is important. Further, it is necessary to establish a method for producing such crystals. However, such a technique has not existed in the past.

[0003]

SUMMARY OF THE INVENTION Therefore, the present invention provides C
A silicon single crystal manufactured by the Z method, in which a silicon wafer cut out from the silicon single crystal is mirror-finished, and in addition, an etch pit generated when an ammonia-based cleaning is performed is suppressed, It is intended to provide a manufacturing method thereof.

[0004]

In order to achieve the above object, according to the present invention, in the process of producing a silicon single crystal by the Czochralski method, a single crystal is produced in a crystal production furnace.
A temperature range of 00 ° C to 850 ° C is passed with a residence time of 250 minutes or less. Preferably, a temperature range from immediately after solidification to 850 ° C. is passed in the crystal production furnace with a residence time of 400 minutes or less.

Further, the silicon single crystal of the present invention is 0.07 when a silicon wafer cut out from the silicon single crystal is mirror-finished and additionally subjected to ammonia cleaning.
It is a silicon single crystal of excellent quality in which generation of etch pits of μm or more is suppressed.

[0006]

In the process of producing a silicon single crystal by the CZ method, the high temperature range from the melting point to 1200 ° C. has the effect of introducing nuclei for generating oxygen precipitation. The temperature range of 1200 to 1100 ° C. has an effect of stabilizing the generation nucleus. 1100
When the temperature is lower than 0 ° C, oxygen precipitation advances mainly in the generated nuclei, and there is an effect of forming fine oxygen precipitates. In particular, 1100 ℃ ~
The temperature range of 850 ° C. has an effect of generating minute secondary defects such as dislocation loops in rare cases from minute oxygen precipitates.

When micro secondary defects are present on the surface of the mirror-polished silicon wafer, they are etched during the subsequent ammonia-based cleaning to form etch pits of 0.07 μm or more.

Since the CZ silicon single crystal produced by the usual method has a long residence time in the temperature range of 1100 ° C. to 850 ° C., minute oxygen precipitates generate small secondary defects of small density, which are ammonia. This was the cause of the etch pits of 0.07 μm or more that were observed during system cleaning.

On the other hand, in the process of manufacturing a silicon single crystal by the CZ method, the temperature is 1100 ° C. to 850 ° C. in a crystal manufacturing furnace.
By passing through the temperature range of ℃ for a residence time of 250 minutes or less, it is possible to suppress the generation of minute secondary defects, so that it is possible to suppress the etch pits of 0.07 μm or more generated after the ammonia-based cleaning. . Preferably,
When passing through the temperature range from immediately after solidification to 850 ° C. for a staying time of 400 minutes or less, the stabilization of the nuclei for the generation of oxygen precipitates can also be suppressed, and the effect is further enhanced.

In the CZ silicon single crystal manufactured by these methods, 0.07 μm generated by the ammonia-based cleaning liquid
The above etch pits are suppressed.

[0011]

EXAMPLES The single crystal production apparatus used in the present invention is not particularly limited as long as it is generally used for producing a silicon single crystal by the CZ method. In this example, the production apparatus shown in FIG. 1 is used. Was used.

This CZ method silicon single crystal manufacturing apparatus 1 is
The heating chamber 2a includes a heating chamber 2a for accommodating a structure for melting silicon and a pulling chamber 2b for accommodating the grown silicon single crystal ingot S separated and connected by the separation mechanism 20. A crucible 5 composed of a quartz crucible 5b and a graphite crucible 5a for protecting the quartz crucible 5b, a heater 6 arranged so as to surround a side surface of the crucible 5, and heat from the heater 6 are provided in 2a. A heat insulating member 11 is arranged in order to prevent the crucible 5 from escaping to the outside of the heating chamber 2a. 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. At the same time, the crucible 5 is moved up and down in order to compensate for the decrease in the silicon melt level as the silicon melt in the crucible 5 decreases. It has become. Pulling chamber 2b
Inside, a pulling wire 7 that is suspended in the chamber is installed, and at the lower end of this wire, a chuck 9 that holds a seed crystal 8 is provided. 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.

Ar gas is introduced into the chamber 2 from the gas introduction port 12 formed in the pulling chamber 2b, is evenly distributed in the heating chamber 2a, and is 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. a) Raw material melt weight: 45 kg b) Crystal growth rate: 1.2 mm / min The above two conditions are common to Example 1, Example 2, Comparative Example 1 and Comparative Example 2.

Example 1 Residence time in the temperature range of solidification to 850 ° C .: 300 minutes A silicon single crystal ingot grown under these conditions is as follows. Conductive type: p-type (boron-doped) Crystal diameter: for 6 inches (160 mm) Resistivity: 10 Ω · cm Oxygen concentration: 7.5-7.8 × 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 the Japan Electronic Industry Development Association) After mirror-finishing the surface of the wafer cut from these ingots, Ammonia-based cleaning solution NH ₄ OH: H ₂
It was washed with O ₂ : H ₂ O = 1: 1: 5, and the etch pit density of 0.07 μm or more was measured by a known particle measuring device. The results are shown in Table 1. As shown in Table 1, the etch pit density of 0.07 μm or more is low, and the wafer cut out from the silicon single crystal ingot obtained by the manufacturing method of the present invention has a density of 0. This indicates that the etch pits of 07 μm or more are suppressed.

Example 2 Residence time in the temperature range of 1100 ° C. to 850 ° C .: 150 minutes A silicon single crystal ingot grown under these conditions is as follows. Conductive type: n-type (P-doped) Crystal diameter: for 6 inches (160 mm) Resistivity: 2 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) The surface of the wafer cut from these ingots is mirror-polished , Ammonia-based cleaning solution NH ₄ OH: H ₂
After cleaning with O ₂ : H ₂ O = 1: 1: 5, the etch pit density of 0.07 μm or more was measured with a well-known particle measuring device, and the result is shown in Table 1 together with Example 1. It was As shown in Table 1, the etch pit density of 0.07 μm or more is low, and the wafer cut from the silicon single crystal ingot obtained by the manufacturing method of the present invention has a density of 0. 07 μm
It is shown that the above etch pits are completely suppressed.

Comparative Example 1 Staying time in the temperature range of solidification to 850 ° C .: 420 minutes A silicon single crystal ingot grown under these conditions is as follows. Conductive type: n-type (P-doped) Crystal diameter: for 6 inches (160 mm) Resistivity: 2 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) The surface of the wafer cut from these ingots is mirror-polished , Ammonia-based cleaning solution NH ₄ OH: H ₂
Cleaning was performed using O ₂ : H ₂ O = 1: 1: 5, and an etch pit density of 0.07 μ or more was measured by a known particle measuring device. The results are also in accordance with Example 1 and Example 2. The results are shown in Table 1. 0.07 μm as shown in Table 1
It can be seen that the above-mentioned etch pit density is high, and the etch pits of 0.07 μm or more generated when cleaning with an ammonia-based cleaning liquid are not suppressed.

Comparative Example 2 Residence time in the temperature range of 1100 ° C. to 850 ° C .: 300 minutes A silicon single crystal ingot grown under these conditions is as follows. Conductive type: p-type (boron-doped) Crystal diameter: for 6 inches (160 mm) Resistivity: 10 Ω · cm Oxygen concentration: 7.5-7.8 × 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 the Japan Electronic Industry Development Association) After mirror-finishing the surface of the wafer cut from these ingots, Ammonia-based cleaning solution NH ₄ OH: H ₂
It was washed with O ₂ : H ₂ O = 1: 1: 5, and an etch pit density of 0.07 μ or more was measured with a known particle measuring device. The results are shown in Example 1 and Example 2. The results are shown in Table 1. 0.07 μm as shown in Table 1
It can be seen that the above-mentioned etch pit density is high, and the etch pits of 0.07 μm or more generated when cleaning with an ammonia-based cleaning liquid are not suppressed.

[0019]

[Table 1]

[0020]

The silicon single crystal of the present invention and the silicon single crystal produced by the method of the present invention are obtained by subjecting the surface of a silicon wafer cut out from the silicon single crystal to mirror-finishing and then performing ammonia cleaning. Generated in 0.07
Since the etching pits of μm or more are suppressed, the surface unevenness is small and it is suitable for a MOS device wafer.

[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.

Front page continuation (72) Inventor Yutaka Takebayashi 3434 Shimada, Hikari City, Yamaguchi Prefecture Nittetsu Electric Co., Ltd. In-house

Claims (3)

[Claims] 1. A process for producing a silicon single crystal by the Czochralski method, which is characterized in that a temperature range from immediately after solidification to 850 ° C. is passed in a crystal production furnace with a residence time of 400 minutes or less. Crystal manufacturing method. 2. In the process of producing a silicon single crystal by the Czochralski method, the temperature is 1100 ° C. in a crystal production furnace.
A method for producing a silicon single crystal, which is characterized in that it passes through a temperature range of 850 ° C. for a residence time of 250 minutes or less. 3. A silicon single crystal produced by the Czochralski method, which is 0.07 μm or more when a silicon wafer cut out from the silicon single crystal is mirror-finished and additionally subjected to an ammonia-based cleaning. A silicon single crystal characterized in that the occurrence of etch pits is suppressed.