JP2824220B2 - Double crucible for silicon single crystal growth - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double crucible for growing a silicon single crystal having a double structure in which an annular partition wall having an introduction hole penetrating therethrough is provided. More specifically, when used in a continuous pulling and growing apparatus for silicon single crystal, CO
The present invention relates to a double crucible capable of growing a silicon single crystal called P (Crystal Originated Particles) having a small diameter of 0.3 μm or more and having few minute defects.

[0002]

2. Description of the Related Art A so-called CZ method is used in which a high-purity silicon single crystal for a semiconductor is grown from a silicon melt in an inner crucible, while silicon and dopant consumed by the growth are supplied from the outer crucible to the inner crucible. 2. Description of the Related Art An apparatus for continuously growing silicon single crystals is known. On the other hand, in the batch type silicon single crystal growing apparatus, since the amount of silicon melt in the quartz crucible changes as the single crystal grows, the quality in one single crystal such as oxygen concentration, crystal growth interface, dopant concentration, etc. Is changed in the longitudinal direction of the crystal. The silicon single crystal continuous growth equipment has no such problems,
Moreover, there is a feature of high productivity.

As shown in FIG. 7, in this continuous growing apparatus, a heat insulating material 2 and a heater 3 are arranged concentrically with the furnace body inside a furnace body 1, and are provided at the upper end of a rotating shaft 5 at the center of the furnace body 1. A cylindrical quartz crucible body 6 with a bottom is fixed to a fixed graphite susceptor 4.
Are fitted. The lower end of an annular partition 7 concentric with the crucible body is fixed to the inner bottom surface of the crucible body 6. This annular partition 7 is provided in the vertical direction. An outer crucible 8 and an inner crucible 9 for storing the silicon melt M are formed by the crucible body 6 and the partition walls. A plurality of introduction holes 10, 10 for communicating the outer crucible 8 to the inner crucible 9 are provided below the partition wall 7. The silicon melt M of the outer crucible 8 melted by the heater 3 through the introduction hole 10 can move from the outer crucible 8 to the inner crucible 9. At the top of the furnace 1
A pulling mechanism 11 is provided, and a seed S suspended from the rotation / pulling mechanism 11 via a wire 12 is disposed above the crucible body 6. Rotation and pulling mechanism 11
Is configured such that a single crystal rod T grown from a seed S is pulled up while rotating to grow a high-purity silicon single crystal at the lower end thereof.

In order to replenish the single crystal raw material consumed by the growth, a high-purity polycrystalline silicon grain is supplied from a raw material supply mechanism 13 provided outside the furnace body 1 through a chute 14 penetrating the furnace body 1. And a predetermined amount of dopant are contained in the outer crucible 8.
Supplied to These raw materials are dissolved by the sensible heat of the silicon melt M in the outer crucible, and then become a high-purity silicon melt. This silicon melt flows into the inner crucible 9 through the introduction hole 10 of the partition wall 7 with a predetermined concentration of dopant, and mixes with the silicon melt M stored in the inner crucible 9 to contain the predetermined concentration of dopant. Silicon melt. From this silicon melt, a silicon single crystal having a desired dopant concentration is deposited below the single crystal rod T and pulled up. A silicon wafer cut from a single crystal rod pulled up by this continuous growing apparatus is mirror-polished, and then a solution composed of NH ₄ OH, H ₂ O _2, and H ₂ O is used based on a standard RCA method. The so-called SC-1 cleaning is performed. This SC-1
The cleaning solution removes organic contaminants and some metal impurities in particles by a strong oxidizing action of H ₂ O ₂ , a dissolving action of NH ₄ OH, and a compound generation reaction.

Recently, shallow etch pits with a shallow bottom have been observed after this SC-1 cleaning, and various papers have been published which assume that the pits are caused by vacancy clusters introduced during crystal growth (for example, J.Ryuta et al., "Crystal-orig
inated singularities on Siwafer surface after SC1
cleaning ", Jpn.J.Appl.Phys., 29 , L1947-L1949 and TA
be et al., "Behavior of point defects in FZ silicon
crystals ", Semiconductor Silicon 1990, pp. 105-116,
Electrochem. Society (1990)). The etch pits are detected by counting with a commercially available laser particle counter. The etch pits counted as particles are COP (Crystal Originated Particl
es).

[0006]

When the conventional silicon single crystal is continuously grown, the quality in one single crystal does not change in the longitudinal direction of the crystal as described above. In the double crucible shown in FIG. 7, the ratio (V _OUT / V _IN ) of the amount of silicon melt (V _IN ) stored in the inner crucible to the amount of silicon melt (V _OUT ) stored in the outer crucible is 0.
It has been desired to increase the heat capacity for the silicon melt in the outer crucible to heat the silicon melt in the inner crucible. Due to this insufficient heat capacity, a silicon single crystal is pulled up using the above double crucible to produce a silicon wafer. When a silicon wafer is mirror-polished and SC-1 washed, the grain size is 0.3 μm or more. COP generation was unavoidable. Although the cause has not been sufficiently elucidated yet, it is considered that the above-mentioned heat capacity shortage is the cause. In order to increase V _OUT / V _IN , it is conceivable to increase the volume of the outer crucible. In this case, when the volume of the inner crucible is not changed, the crucible body becomes larger in the radial direction,
Accordingly, it was necessary to increase the capacity of the heater and the heat insulating material, and the furnace body was enlarged. Further, without changing the size of the crucible body, in other words, without increasing the amount of silicon melt in the crucible body, the upper inner diameter of the partition wall 7 is formed smaller than the lower inner diameter of the partition wall as shown in FIGS. V _OUT /
When V _IN is increased, when the diameter of the silicon single crystal to be grown is A and the inner diameter of the partition wall on the silicon melt surface is D, D / A becomes as small as about 1.2, and Was difficult to maintain. On the other hand, in recent years, there has been a remarkable increase in the degree of integration of semiconductor integrated circuits. As a result, circuits provided on silicon wafers have become finer. In the case of using a wafer, this COP has hindered high integration.

An object of the present invention is to provide a silicon single crystal continuous growth apparatus without increasing the size of a furnace body, and to carry out SC-1 cleaning of a silicon wafer made from a grown single crystal rod so that the particle size on the wafer surface is reduced. An object of the present invention is to provide a double crucible for growing a silicon single crystal in which generation of a coarse COP of 0.3 μm or more is small.

[0008]

In view of the above, the inventors of the present invention focused on a double crystal crucible in a single crystal growing apparatus in order to grow a coarse single crystal with little COP. As a result, it has been found that a single crystal with few fine defects can be obtained by continuous pulling by making the lower diameter of the partition wall constituting the double crucible smaller than the upper diameter.

That is, according to the present invention, as shown in FIGS. 1 and 6, a cylindrical crucible body 6 having a bottom and an annular shape concentric with the crucible body 6 and having a lower end fixed to the inner bottom surface of the crucible body 6 are provided. , An outer crucible 18 and an inner crucible 19 formed by the crucible body 6 and the partition 17 for storing the silicon melt M, respectively, and a plurality of introductions formed below the partition 17 and communicating the outer crucible 18 to the inner crucible 19. Holes 20, 20
It is an improvement of a double crucible for growing a silicon single crystal, comprising: The characteristic configuration is that the partition wall 17 has a uniform thickness, the lower inner diameter of the partition wall 17 is formed smaller than the upper inner diameter of the partition wall 17, the diameter of the silicon single crystal rod T to be grown is A, The inner diameter at the silicon melt surface is D, the depth from the silicon melt surface to the introduction hole 20 is h, the amount of silicon melt stored in the outer crucible 18 is V _OUT , and the inner crucible 1 is
When the amount of silicon melt stored in 9 is V _IN , D / A = 1.5 to 3.0 (1) 2h / A ≧ 1 (2) V _OUT / V _IN = 0.4 ０．９0.9 (3) This satisfies the relationship of the above equations (1) to (3).
The reason for limiting D / A to 1.5 to 3.0 is that if it is less than 1.5, it is difficult to maintain crystal growth, and if it exceeds 3.0, the amount of silicon melt becomes large and it becomes economically negative. . The reason for limiting 2h / A ≧ 1 is that if the depth of the introduction hole is smaller than the radius of the silicon single crystal rod, the dopant concentration in the single crystal silicon becomes non-uniform. V _OUT / V
_The reason for limiting _IN = 0.4 to 0.9 is that if the ratio is less than 0.4, the heat capacity of the silicon melt in the outer crucible to heat the silicon melt in the inner crucible does not increase, and mirror polishing is performed. 0.3% when the cleaned silicon wafer was subjected to SC-1 cleaning.
This is because a coarse COP of μm or more is generated. Also 0.
If it exceeds 9, the amount of the silicon melt becomes large, which is disadvantageous in that it is economically negative. In the example shown in FIG. 1, the partition wall 17 is formed so as to be inclined so that its inner diameter becomes smaller toward the lower end. Partition wall 17 of the present invention
The shape is not particularly limited as long as it is concentric with the crucible body 6. For example, it may be concentric with the crucible body 6 as shown in FIG. 4, or may be concentric and elliptical as shown in FIG. Although not shown, the shape may be a rectangular tube.

Another double crucible according to the present invention comprises, as shown in FIGS. 2 and 3, a partition wall 17 having a vertical upper portion 17a, a vertical lower portion 17b having an inner diameter smaller than the vertical upper portion 17a, and a lower end of the vertical upper portion 17a. An intermediate portion 17c connecting the upper end of the vertical lower portion 17b. The intermediate portion 17c shown in FIG. 2 is formed horizontally, and the intermediate portion 17c shown in FIG.
c is formed so as to be inclined such that its inner diameter decreases toward the vertical lower portion 17b. In addition, the double crucible of the present invention, when the inside diameter of the installation position of the introduction hole 20 formed in the partition wall 17 is d, in addition to the relationship of the above equations (1) to (3), d / D = 0.3 to 0.6 (4) It is preferable to satisfy the relationship of the above expression (4). In addition,
The reason for limiting d / D to the range of 0.3 to 0.6 is that d / D
Is less than 0.3, it is difficult to maintain crystal growth, and if it exceeds 0.6, the heat capacity for heating the silicon melt in the inner crucible does not increase so much, and the COP of the This is because the effect of preventing occurrence is not sufficient.
Further, it is preferable that each of the plurality of introduction holes 20 has the same height from the inner bottom surface of the crucible body 6.

[0011]

Next, examples of the present invention will be described together with comparative examples. <Examples 1 to 4> Having the shape shown in FIG.
The double crucibles of Example 1, Example 2, Example 3, and Example 4 having the partition wall dimensions shown in Table 1 were prepared. <Comparative Example 1 and Comparative Example 2> Having the shape shown in FIG.
In addition, double crucibles of Comparative Examples 1 and 2 having the partition wall dimensions shown in Table 1 were prepared.

<Comparative Test> The double crucibles of Examples 1 to 4 were applied to the single crystal growing apparatus shown in FIG. 6, and the double crucibles of Comparative Examples 1 and 2 were applied to the single crystal growing apparatus shown in FIG. A silicon single crystal having a total length of 1,000 mm was grown under the same conditions as those described below. Depth (h) from silicon melt surface to inlet hole: 100m
m Diameter of silicon single crystal rod (A): 160 mm Silicon melt amount in crucible body: 32 kg Crystal growth rate: 1.2 mm / min 500 mm from the top of the high-purity silicon single crystal rod pulled up in this manner. After the silicon wafer is cut out by using and the surface is mirror-polished, SC prepared using ammonia water, hydrogen peroxide solution, and ultrapure water in a ratio of 1: 1: 5 is used.
-1 Washing liquid at a temperature of 85 ° C for 20 minutes. Next, the number of COPs having a particle size of 0.3 μm or more on the wafer surface was measured using a commercially available laser particle counter. The measurement results are shown in Table 1.

[0013]

[Table 1]

As is clear from Table 1, the number of COPs having a grain size of 0.3 μm or more is 40 to 40 in the silicon wafer after SC-1 cleaning using the double crucibles of Comparative Examples 1 and 2.
In contrast to 50 / cm ² , the number of COPs having a particle diameter of 0.3 μm or more was 3 on the silicon wafer after SC-1 cleaning using the double crucibles of Examples 1 to 4. ５5 / cm ^{2, which} is 1/10 or less, which was extremely small.

[0015]

As described above, according to the present invention, the heat capacity of the outer crucible to the inner crucible can be increased without increasing the outer crucible in the radial direction. When the silicon wafer made from the grown single crystal rod was cleaned with SC-1 without increasing the size, a coarse COP with a particle size of 0.3 μm or more was formed on the wafer surface.
Can be reduced. As a result, silicon wafers made from the double crucible of the present invention are suitable for highly integrated circuits.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a double crucible of the present invention.

FIG. 2 is a schematic sectional view of another double crucible of the present invention.

FIG. 3 is a schematic sectional view of still another double crucible of the present invention.

FIG. 4 is a plan view of FIG. 1;

FIG. 5 is a plan view of FIG. 2;

FIG. 6 is a schematic sectional view of a continuous single crystal growing apparatus by a CZ method using a double crucible according to the present invention.

FIG. 7 is a schematic cross-sectional view of a conventional continuous single crystal growing apparatus by a CZ method using a double crucible.

FIG. 8 is a schematic sectional view of a conventional double crucible.

FIG. 9 is a schematic sectional view of another conventional double crucible.

FIG. 10 is a schematic cross-sectional view of another conventional double crucible that has been attempted.

[Explanation of symbols]

 M Silicon melt T Silicon single crystal rod S Seed 1 Furnace 2 Heat insulator 3 Heater 4 Graphite susceptor 5 Rotating shaft 6 Crucible body 7,17 Partition wall 8,18 Outer crucible 9,19 Inner crucible 10,20 Introducing hole 11 rotation -Pulling mechanism 12 Wire 13 Material supply mechanism 14 Chute 17a Vertical upper part of partition 17b Vertical lower part of partition 17c Middle part of partition

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Norihisa Machida 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsui Materials Co., Ltd. Central Research Laboratory (72) Inventor Yoshiaki Arai 1-297 Kitabukuro-cho, Omiya-shi, Saitama 3 (56) References JP-A-5-85879 (JP, A) JP-A-3-92774 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) C30B 15/10-15/12 C30B 28/00-35/00

Claims (6)

(57) [Claims] 1. A crucible body (6) having a bottom and a cylindrical shape, and an annular partition (17) concentric with the crucible body (6) and having a lower end fixed to an inner bottom surface of the crucible body (6). The silicon melt (M) formed by the crucible body (6) and the partition wall (17)
Outer crucible (18) and inner crucible (19), respectively, and a plurality of introduction holes (20, 20) formed below the partition wall (17) and communicating the outer crucible (18) to the inner crucible (19). ), A double crucible for growing a silicon single crystal, wherein the partition wall (17) has a uniform thickness, and a lower inner diameter of the partition wall (17) is formed smaller than an upper inner diameter of the partition wall (17). The diameter of the silicon single crystal rod (T) to be grown is A,
D is the inner diameter of the silicon melt surface of (17), h is the depth from the silicon melt surface to the introduction hole (20), and V _{OUT is} the amount of silicon melt stored in the outer crucible (18). Inner crucible (19)
When the silicon melt amount and V _IN to be stored in, D / A = 1.5~3.0 ...... ( 1) 2h / A ≧ 1 ...... (2) V OUT / V IN = 0.4~ 0.9 (3) A double crucible for growing a silicon single crystal, which satisfies the relations of the expressions (1) to (3). 2. The double crucible for growing a silicon single crystal according to claim 1, wherein the partition wall (17) is formed so as to be inclined so that its inner diameter becomes smaller toward the lower end. 3. A partition (17) includes a vertical upper portion (17a), a vertical lower portion (17b) having an inner diameter smaller than that of the vertical upper portion (17a), and the vertical upper portion.
The double crucible for growing a silicon single crystal according to claim 1, comprising an intermediate portion (17c) connecting a lower end of the (17a) and an upper end of the vertical lower portion (17b). 4. The double crucible for growing a silicon single crystal according to claim 3, wherein the intermediate portion (17c) is formed horizontally. 5. The double crucible for growing a silicon single crystal according to claim 3, wherein the intermediate portion (17c) is formed so as to be inclined such that its inner diameter becomes smaller toward the vertical lower portion (17b). 6. When the inside diameter of the installation position of the introduction hole (20) formed in the partition wall (17) is d, d / D = 0.0 in addition to the relations of the equations (1) to (3). 3 to 0.6 (4) The double crucible for growing a silicon single crystal according to any one of claims 1 to 5, wherein the relationship of the expression (4) is satisfied.