JPH10330190A - Growth of silicon single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely obtain a large-diameter, heavyweight silicon single crystal by surely supporting it with the enlarged diameter of a seed drawn part. SOLUTION: The growth of a silicon single crystal is conducted by the following method: a seed crystal 24 with its lower end contacted with a silicon melt reserved in a crucible inside a chamber is pulled up to make a seed drawn part 25a from the melt, and further pulled up to grow the objective single crystal 25 on the lower end of the seed drawn part; wherein the surface of the seed drawn part 25a of the seed crystal being pulled up is heated and a silane- based gas is allowed to flow around the seed drawn part to effect epitaxial growth of a single crystal silicon layer 25b with a thickness of 50-5,000 μm on the surface of the seed drawn part 25a; in this case, it is preferable that, when the gas is allowed to flow, the surface of the seed drawn part 25a is heated to 500-1,400 deg.C and the rate of epitaxial growth of the single crystal silicon layer 25b is 0.05-100 μm/min. Furthermore, the silane-based gas is pref. SiCl4 , SiHCl3 , SiH2 Cl2 or SiH4 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for growing a single crystal from a silicon melt by the Czochralski method (hereinafter referred to as CZ method). More specifically, the present invention relates to a method of pulling a seed crystal to produce a seed drawing portion from a silicon melt, and then further pulling the seed crystal to grow a single crystal below the seed drawing portion.

[0002]

2. Description of the Related Art Conventionally, as an apparatus of this type, an inert gas is supplied from above a chamber to evaporate S from a melt surface.
2. Description of the Related Art A single crystal pulling apparatus provided with a gas supply means for discharging iO gas is known. As a method for growing a silicon single crystal using this apparatus, a high purity silicon single crystal for a semiconductor is grown from a silicon melt in a crucible. A known CZ method is known. In this method, a mirror-etched seed crystal is brought into contact with a silicon melt, the seed crystal is pulled up to form a seed drawing portion from the silicon melt, and then the crystal is gradually thickened to a target silicon rod diameter. This is a method of obtaining a dislocation-free single crystal rod having a required plane orientation by growing. When this single crystal is obtained, slip dislocations are introduced into the seed crystal due to thermal stress when the seed crystal contacts the silicon melt, and it is difficult to obtain a single crystal without dislocation. ) Method is widely used (WC Dash, J. Appl. Phys. 29 736-737 (1958)).

In the dash method, after a seed crystal is brought into contact with a silicon melt, the diameter of the seed crystal is reduced to about 3 mm to form a seed drawing portion, thereby eliminating dislocations propagated from slip dislocations introduced into the seed crystal. Thus, a dislocation-free single crystal is obtained. That is, in the dash method, a seed drawing portion having a small diameter is required in a single crystal portion to be continuously grown from a seed crystal, and if the seed drawing portion has a predetermined value or more, it is difficult to sufficiently eliminate dislocations. At present, it is said that the diameter of the seed constricted portion which can sufficiently eliminate dislocations is about 3 mm described above as a limit value.

On the other hand, the practical length of a dislocation-free single crystal rod actually used is said to be about 1 m. This is because a single crystal with a length of less than this length is often deleted in the processing at the time of actual use, so that the production cost is high and the practical value is lost. Therefore, if the diameter of the seed drawing portion is limited, the weight of the single crystal that can be supported by the seed drawing portion is limited, and in order to obtain a single crystal rod of a practical length, the diameter of the single crystal is inevitably increased. Will be limited. For example, it is said that the diameter of a conventional 3 mm seed drawing portion has a limit of about 300 mm in order to pull a single crystal having a length of 1 m or more.

[0005]

However, the necessity of increasing the diameter of a single crystal in recent years has been particularly increased due to the progress of integration of VLSIs. However, the strength is not enough to pull a heavy single crystal with a practical length of 300 mm or more, and a serious accident such as dropping of the single crystal rod due to breakage of the seed drawing part may occur. Was. Also, in the dash method,
It takes a relatively long time to perform the seed drawing, and once the seed drawing has failed, it is necessary to start over again for a long time, resulting in a disadvantage that the efficiency in the growth process is reduced. An object of the present invention is to provide a method for growing a silicon single crystal in which a large diameter and a large weight silicon single crystal can be surely obtained by enlarging the diameter of a seed drawing portion and reliably supporting the silicon single crystal. is there.

[0006]

The invention according to claim 1 is
As shown in FIG. 1 and FIG.
The seed crystal 24 whose lower end is brought into contact with the silicon melt 12 stored in the sample melt 3 is pulled up, and the seed narrowing section 25 is separated from the silicon melt 12.
a, the seed crystal 24 is further pulled up, and the seed drawing portion 25a
Is an improvement of a method for growing a single crystal 25 in the lower part of FIG. The characteristic configuration is that the seed drawing portion 25 of the seed crystal 24 being pulled is drawn.
The surface of a is heated and a silane-based gas is flowed around the seed aperture 25a to epitaxially grow the single crystal silicon layer 25b to a thickness of 50 to 5000 μm on the surface of the seed aperture 25a. In the method for growing a silicon single crystal according to the first aspect, the seed narrowing portion 2 is formed by epitaxially growing the single crystal silicon layer 25b to a thickness of 50 to 5000 μm on the surface of the seed narrowing portion 25a during pulling.
The diameter of 5a is enlarged, and the supporting weight for supporting silicon single crystal 25 per unit area of seed drawing portion 25a is reduced. The single-crystal silicon layer 25b has a thickness of 500 to 5000 μm.
m is preferably epitaxially grown to a thickness of m
More preferably, the thickness is from 2000 to 5000 μm.

The invention according to claim 2 is the invention according to claim 1, wherein the seed narrowing section 25a is used when the silane-based gas flows.
Is a method of growing a silicon single crystal in which the surface of the silicon single crystal is heated to a temperature of 500 to 1400 ° C. The surface of the seed drawing part 25a is
By heating to a temperature of 0 to 1400 ° C., a single-crystal silicon layer 25b is effectively grown epitaxially on the surface of the seed drawing portion 25a. If the surface of the seed narrowing portion 25a is lower than 500 ° C. or higher than 1400 ° C., epitaxial growth does not occur, and the single crystal silicon layer 25b is not formed. Preferably it is 800-1100 degreeC.

The invention according to claim 3 is the invention according to claim 1 or 2, which is a method for growing a silicon single crystal in which the epitaxial growth rate of the single crystal silicon layer 25b is 0.05 to 100 μm / min. Since the epitaxial growth rate is 0.05 to 100 μm / min, the single crystal silicon layer 25 b is
Epitaxial growth to a thickness of 00 μm. When the epitaxial growth rate is less than 0.05 μm / min, it takes too much time for the single crystal silicon layer 25b to grow to a thickness of 50 μm, and the epitaxial growth rate is 100 μm / min.
When the length exceeds the limit, dislocations are formed in the single crystal silicon layer 25b.
The epitaxial growth rate is particularly 1 to 100 μm /
Minutes, more preferably 10 to 100
μm / min.

The invention according to claim 4 is the invention according to claims 1 to 3
The invention according to any one of the above, wherein the silane-based gas is SiCl
₄ , a method for growing a silicon single crystal which is SiHCl ₃ , SiH ₂ Cl ₂ or SiH ₄ . Silane gas is SiCl
_{4. The} single crystal silicon layer 25b is effectively epitaxially grown on the surface of the seed narrowing portion 25a by the following chemical reaction due to SiHCl ₃ , SiH ₂ Cl ₂ or SiH ₄ . SiCl ₄ + 2H ₂ → Si + 4HCl SiHCl ₃ + H ₂ → Si + 3HCl SiH ₂ Cl ₂ → Si + 2HCl SiH ₄ → Si + 2H ₂

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. As shown in FIG. 3, a quartz crucible 13 for storing a silicon melt 12 is provided in a chamber 11 of a silicon single crystal growing apparatus 10 used in the growing method of the present invention, and the outer surface of the quartz crucible 13 is graphite. Covered by susceptor 14. The lower surface of the quartz crucible 13 is fixed to the upper end of a support shaft 16 via the graphite susceptor 14, and the lower portion of the support shaft 16 is connected to a crucible driving unit 17. Although the crucible driving means 17 is not shown, the quartz crucible 1
3 has a first rotation motor for rotating 3 and a lifting / lowering motor for raising / lowering the quartz crucible 13, and these motors can rotate the quartz crucible 13 in a predetermined direction,
It can be moved up and down. Outside the quartz crucible 13, the first
A heater 18 is provided, and a heat retaining cylinder 19 is provided between the first heater 18 and the chamber 11. First heater 1
The high-purity silicon polycrystal put into the quartz crucible 13 is melted by 8 to become a silicon melt 12.

On the upper surface of the chamber 11, a chamber 11 is provided.
A cylindrical casing 21 having a smaller diameter is provided. A second heater 21a is provided on an inner surface of a lower portion of the casing 21. A pulling head 22 is provided on the upper end of the casing 21 so as to be pivotable in a horizontal state. It is drooped toward. Although not shown, the head 22 has a built-in second rotation motor for rotating the head 22 and a pull-up motor for winding or feeding out the wire cable 23. At the lower end of the wire cable 23, a seed crystal 24 for dipping in the silicon melt 12 to pull up the silicon single crystal 25 is provided in the holder 2.
Attached via 3a.

An inert gas such as an Ar gas and a silane-based gas are supplied to the chamber 11 from the upper portion of the chamber 11, and the inert gas and the silane-based gas are supplied to the chamber 1.
A gas supply / discharge means 28 for discharging the gas from the lower portion 1 is connected.
One end of the gas supply / discharge means 28 is connected to the peripheral wall of the casing 21 above the second heater 21a, and the other end is connected to a supply pipe 29 connected to an inert gas tank and a silane-based gas tank (not shown). It has a discharge pipe 30 connected to the lower wall of the chamber 11 and the other end connected to a vacuum pump (not shown). The supply pipe 29 and the discharge pipe 30 are provided with first and second flow control valves 31 and 32 for controlling the flow rates of the inert gas and the silane-based gas flowing through these pipes 29 and 30, respectively.

A method for growing a silicon single crystal using the apparatus configured as described above will be described. First, a silicon melt 12 formed by melting a polycrystal in a crucible 13 by heating of a first heater 18 is stored, and a seed crystal 24 is hung above a surface of the silicon melt from a wire cable 23 via a holder 23a. Lower. Next, by opening the first and second flow control valves 31 and 32, an inert gas is supplied from the supply pipe 29 into the casing 21 and the SiO gas evaporated from the surface of the silicon melt 12 is removed together with the inert gas. Discharge pipe 3
Drain from 0. In this state, the wire 19 is drawn out by a pulling motor (not shown) of the pulling head 22 to lower the seed crystal 24, and the tip of the seed crystal 24 is brought into contact with the silicon melt 23. When the tip of the seed crystal 24 is brought into contact with the silicon melt 12, slip dislocations are introduced into the tip by thermal stress. Thereafter, the seed crystal 24 is gradually pulled up to form a seed drawing portion 25a having a diameter of about 3 mm. Form.
By forming the seed constricted portion 25a, the dislocations introduced into the seed crystal 24 disappear, and then the seed crystal 24 is further pulled to grow a dislocation-free silicon single crystal 25 below the seed constricted portion 25a. .

If the seed crystal 24 is further pulled up and the growth of the dislocation-free silicon single crystal 25 is continued, the weight of the silicon single crystal 25 supported by the seed constricted portion 25a increases, and the seed crystal 24 is eventually removed from the inside of the chamber 11 by the casing. 21
Reach the bottom of As shown in FIG. 2, when the seed crystal reaches the lower part of the casing 21, the second heater 21 a is turned on to raise the surface of the seed drawing part of the seed crystal being pulled up to 500 to 14.
Heat to 00 ° C. In addition, the second heater 21a is turned on, and the first flow control valve 31 is adjusted so that the supply pipe 2
The silane-based gas is supplied into the casing 21 together with the inert gas that has been flowing from 9 to heretofore, and flows around the seed narrowing portion as shown by the solid line arrow in the figure. The silane-based gas may be SiCl ₄ , SiHCl ₃ , SiH ₂ Cl ₂ or SiH
_{4 and the} like are preferred.

As described above, by heating the surface of the seed narrowing section 25a in the middle of pulling up and flowing a silane-based gas around the seed narrowing section 25a, as shown in FIG. The single crystal silicon layer 25b is epitaxially grown. In this way, the seed narrowing section 25 being pulled up is
a to form a single-crystal silicon layer 25b on the surface of
By epitaxial growth with a thickness of m, the diameter of the seed constricted portion 25a is enlarged, the weight supported per unit area of the seed constricted portion 25a supporting the weight of the silicon single crystal 25 is reduced, and the silicon single crystal 25 is It can be reliably supported.

[0016]

As described above, according to the present invention, a single-crystal silicon layer is formed on the surface of a seed drawing part during pulling up by 50 to 50%.
Epitaxial growth with a thickness of 5000 μm increases the diameter of the seed narrowed portion and reduces the weight of the seed narrowed portion that supports the silicon single crystal per unit area. As a result, even if the silicon single crystal has a large diameter and a large weight, the seed drawing portion does not break, and a silicon single crystal having a large diameter and a large weight can be reliably obtained.

Further, the surface of the seed drawing part is set to 500 to 1400
C., a single-crystal silicon layer can be effectively grown epitaxially on the surface of the seed drawing part. If the epitaxial growth rate is 0.05 to 100 μm / min, the surface of the single-crystal silicon can be grown on the seed drawing part. 50-50 layers
It can be epitaxially grown to a thickness of 00 μm. Furthermore, SiCl ₄ , SiHCl ₃ , S
By using iH ₂ Cl ₂ or SiH ₄ , a pure single crystal silicon layer can be effectively epitaxially grown on the surface of the seed aperture.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a portion A in FIG. 3 showing a state in which a silicon single crystal layer is grown in a growth method of the present invention.

FIG. 2 is an enlarged view corresponding to FIG. 1, showing a state before the silicon single crystal layer is grown.

FIG. 3 is a sectional configuration view of an apparatus used in the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Chamber 12 Silicon melt 13 Quartz crucible 24 Seed crystal 25 Silicon single crystal 25a Seed constriction part 25b Single crystal silicon layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01L 21/208 H01L 21/208 P (72) Inventor Keisei Abe 1-5-1, Otemachi, Chiyoda-ku, Tokyo Mitsubishi Material Silicon (72) Inventor Kazutaka Terashima 206-3 Nakano, Ebina-shi, Kanagawa Prefecture (72) Inventor Susumu Maeda 2612 Shinomiya, Hiratsuka-shi, Kanagawa Prefecture Komatsu Electronic Metals Co., Ltd. (72) Hideo Nakanishi Tokyo Metropolitan Government 1-26-1 Nishi Shinjuku, Shinjuku-ku Toshiba Ceramics Co., Ltd.

Claims (4)

[Claims] 1. A seed crystal (24) having its lower end in contact with a silicon melt (12) stored in a crucible (13) in a chamber (11) is pulled up, and a seed narrowing section is drawn from the silicon melt (12). (25a), the seed crystal (24) is further pulled up, and the seed drawing part (25a)
A method of growing a single crystal (25) below the seed crystal, heating the surface of the seed drawing part (25a) of the seed crystal (24) being pulled and silane-based gas around the seed drawing part (25a). A single crystal silicon layer on the surface of the seed drawing portion (25a).
A method for growing a silicon single crystal, comprising epitaxially growing (25b) to a thickness of 50 to 5000 μm. 2. When a silane-based gas is passed, a seed narrowing section (25
The method for growing a silicon single crystal according to claim 1, wherein the surface of a) is heated to a temperature of 500 to 1400C. 3. The single crystal silicon layer (25b) has an epitaxial growth rate of 0.05 to 100 μm / min.
Or the method for growing a silicon single crystal according to 2. 4. The silane-based gas is SiCl ₄ , SiHC
_{4. The method according} to claim 1, wherein said compound is l ₃ , SiH ₂ Cl ₂ or SiH _4.
The method for growing a silicon single crystal according to any one of the above.