KR100784585B1 - Method of growing semiconductor crystal using unbalanced magnetic field and apparatus for implementing the same - Google Patents

Abstract

A method and an apparatus for manufacturing a semiconductor single crystalline using an asymmetry magnetic field are provided to manufacture a high quality semiconductor single crystalline by restricting potential defects caused by a crystalline exfoliation of a chamber surface. A chamber(10) contains a melted semiconductor with a high temperature. A chamber housing(20) surrounds the chamber and supports it. A rotation unit(30) is installed at a lower end of the chamber, and rotates the chamber and the housing. A heater(40) heats the chamber separated from the sidewall of the housing. A heat shielding unit(50) is installed at the outside of the heater, and prevent the heat from being flowed out. A single crystalline growing unit(60) grows the single crystalline(C) from the semiconductor melt(SM). A heat shielding unit(70) reflects the heat from the single crystalline.

Description

Method for manufacturing semiconductor single crystal using asymmetric magnetic field and its device {Method of growing semiconductor crystal using unbalanced magnetic field and Apparatus for implementing the same}

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to.

1 is a schematic configuration diagram of a semiconductor single crystal manufacturing apparatus according to a preferred embodiment of the present invention.

FIG. 2 shows a simulation of the magnetic field distribution around the silicon melt and the quartz crucible (upper view) and the convection velocity by position of the silicon melt (lower view) when the semiconductor single crystal manufacturing apparatus according to the present invention is used for the production of the silicon single crystal. It is.

3 is a photograph of the sidewall portion, the curved portion, and the bottom portion of the silicon crucible after the silicon single crystal growth process is performed for 100 hours without applying a magnetic field.

4 is a photograph of the surface and the cross-section of the curved portion of the silicon crucible after the silicon single crystal growth process is performed for 100 hours while applying a symmetric magnetic field.

FIG. 5 shows photographs of the curved surface and the curved and bottom sections of the silicon crucible after the silicon single crystal growth process is performed for 100 hours while an asymmetric magnetic field is applied.

The present invention relates to semiconductor single crystal growth, and more particularly, asymmetric magnetic field is applied during semiconductor single crystal growth by Czochralski (abbreviated as CZ) method to prevent surface delamination and crucible deterioration due to crystallization of crucible. The present invention relates to a method for preventing semiconductor single crystal growth and an apparatus capable of implementing the method.

In general, silicon single crystals used as materials for producing electronic components such as semiconductors are manufactured by the CZ method. In the CZ method, polycrystalline silicon is poured into a quartz crucible and melted at 1400 ° C. or higher, and the seed crystal is immersed in the molten silicon melt, and the crystal is grown while slowly pulling it. For a detailed description, see S.wolf and R.N. Tauber's paper is well described in Silicon Processing for the VLSI Era, volume 1, Lattice Press (1986), Sunset Beach, CA.

On the other hand, in order to increase the yield of semiconductor device manufacture in recent years, the large diameter of a silicon single crystal is calculated | required. Accordingly, the capacity of the polycrystalline silicon and the operating time for crystal growth are increased in the quartz crucible used in the CZ method.

In addition, multi-pulling processes have been applied to increase the productivity of silicon single crystals. Here, the multi-pooling process refers to a process of growing several silicon single crystals continuously without replacing the quartz crucible. Therefore, even when the multi-pooling process is applied, the operation time is increased regardless of the large diameter of the silicon single crystal.

In the single crystal growth process using the CZ method, the temperature of the silicon melt in the quartz crucible is high temperature of 1400 ° C or higher. Therefore, when the operation time for single crystal growth is long, the silicon atoms of the silicon melt and the oxygen atoms in the crucible form crystallization reactions on the surface of the quartz crucible to form cristobarite (SiO _x ). However, if the operation time is longer than the limit, cristobarite is introduced into the silicon melt in the form of fine particles by surface peeling. Then, the convection moves to the solid-liquid interface where crystal growth occurs, and then flows into the crystal to cause dislocation defects in the crystal. Thus, when dislocation defects are induced, there is a problem that the quality of the single crystal is lowered and the yield of the wafer is reduced.

In addition, when the single crystal growth process by the CZ process is performed for a long time, the quartz crucible is softened and the shape of the quartz crucible is asymmetrically deformed. This prevents stable control of the convection of the silicon melt in the quartz crucible. Convection of the silicon melt is an important control factor for the growth rate (mm / min) associated with productivity during single crystal growth or for the growth of crystals with a desired quality, for example, in the radial direction of the crystal cross section. Therefore, if the convection control of the silicon melt becomes difficult due to the deformation of the quartz crucible, a high quality single crystal cannot be obtained.

Therefore, in order to increase the productivity of the single crystal growth process by the large diameter of the silicon single crystal and the multi-pooling process, it is necessary to prevent crystal delamination on the surface of the crucible caused by prolonged operation time and to asymmetrically deform the shape of the quartz crucible. Measures must be in place to prevent them.

As an example of the prior art to solve the above problems, Korean Patent Publication No. 2005-7012775 consists of a triple layer of inner, middle and outer layers of the stone crucible, but doping Al in each layer to adjust the concentration of quartz A technique for preventing a crystallization reaction between a crucible and a silicon melt is disclosed. However, this technique complicates the quartz crucible manufacturing process, which increases the cost of crucible production and puts an economic burden on the silicon single crystal manufacturer to replace all existing quartz crucibles.

As another example, Japanese Patent Laid-Open No. 6-159602 discloses a technique capable of improving the durability of a quartz crucible by doping a metal into the quartz crucible. However, when the metal doped in the quartz crucible diffuses into the silicon melt and is incorporated into the single crystal through the solid-liquid interface, the quality of the single crystal is degraded as well as adversely affecting the yield of the semiconductor device.

The present invention was devised to solve the above-mentioned problems of the prior art, and a method and apparatus for manufacturing a semiconductor single crystal which can prolong operation time at low cost without changing the components of the crucible itself when growing single crystals by the CZ method. The purpose is to provide.

Another technical problem of the present invention is to increase the crucible input capacity of semiconductor raw materials by prolonging the operating time of the single crystal growth process by the CZ method, and to increase the size of the semiconductor single crystals, and to introduce the single-crystal growth process by the active introduction of the multi-pull process. To provide a semiconductor single crystal manufacturing method and apparatus that can maximize the productivity of the.

Another technical problem of the present invention is to prevent the surface delamination of the crystals generated on the surface of the crucible during the single crystal growth process by the CZ method and to prevent the deformation of the crucible, thereby enabling to secure the convection of the semiconductor melt. And to provide the device.

In the semiconductor single crystal manufacturing method according to the present invention for achieving the above technical problem, in the semiconductor single crystal manufacturing method using the CZ method, the magnetic field strength of the lower than the upper portion based on the Zero Gauss Plane (ZGP) having a vertical component of zero magnetic field A large asymmetric magnetic field is applied to the crucible, but the magnetic field horizontal component or vertical component at the point where the surface of the semiconductor melt and the sidewall of the crucible meet vertically is 800 G or less.

In the present invention, the single crystal growth operation time is preferably 60 hours or more.

Preferably, the crucible is a quartz crucible and the semiconductor melt is a silicon melt.

The semiconductor single crystal manufacturing apparatus according to the present invention for achieving the above technical problem, the single crystal growth apparatus using the CZ method including a crucible, crucible rotating means and pulling means for pulling the single crystal from the semiconductor melt contained in the crucible by seed crystals According to the present invention, an asymmetric magnetic field having a higher magnetic field strength than the upper portion is formed based on a zero gauge plane (ZGP) having a vertical component of zero applied by an upper / lower coil installed around the crucible or a chamber (manufacturing device). It is applied to the crucible, characterized in that it further comprises a magnetic field applying means for applying a magnetic field horizontal component or a vertical field of 800G or less at the point where the surface of the semiconductor melt and the sidewall of the crucible vertically.

Preferably, the magnetic field applying means comprises an upper coil and a lower coil spaced a predetermined distance, the upper coil and the lower coil is disposed coaxially with the crucible.

Preferably, the asymmetric magnetic field is a Cusp type magnetic field.

Preferably, the crucible is a quartz crucible and the semiconductor melt is a silicon melt.

Preferably, the operation time of the semiconductor single crystal growth apparatus is 60 hours or more.

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Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical idea of the present invention, various equivalents that may be substituted for them at the time of the present application It should be understood that there may be water and variations.

1 is a schematic configuration diagram of a semiconductor single crystal manufacturing apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the semiconductor single crystal manufacturing apparatus of the present invention includes a crucible 10 in which a semiconductor melt SM melted at a high temperature is accommodated; A crucible housing 20 surrounding the outer circumferential surface of the crucible 10 and supporting the outer circumferential surface of the crucible 10 in a predetermined form; A crucible rotating means (30) installed at the bottom of the crucible housing (20) to rotate the crucible (10) together with the housing (20); Heating means 40 for heating the crucible 10 spaced a predetermined distance from a side wall of the crucible housing 20; Heat insulation means (50) installed on the outside of the heating means (40) to prevent heat generated from the heating means (40) from flowing out; Single crystal pulling means (60) for pulling single crystal (C) from the semiconductor melt (SM) accommodated in the crucible (10) using seed crystals; And heat shield means 70 reflecting heat emitted from the single crystal C at a predetermined distance from the outer circumferential surface of the single crystal C pulled by the single crystal pulling means 60. Since these components are typical components of a semiconductor single crystal manufacturing apparatus well known in the art, detailed description of each component will be omitted.

The semiconductor single crystal manufacturing apparatus according to the present invention further includes magnetic field applying means (80a, 80b, hereinafter referred to as 80) for applying a magnetic field to the crucible 10 in addition to the above components. Preferably, the magnetic field applying means 80 applies an asymmetric magnetic field (G _upper , G _lower : collectively referred to as G) to the high temperature semiconductor melt SM accommodated in the crucible 10.

Here, the asymmetric magnetic field (G) refers to a magnetic field having a higher G _lower intensity than the G _upper intensity based on ZGP (Zero Gauss Plane 90) where the vertical component of the magnetic field is zero. Means. That is, R = G _lower / G _upper is a magnetic field greater than one. Under these asymmetric magnetic field conditions, the ZGP 90 has a parabolic shape with approximately convex tops.

Preferably, the magnetic field applying means 80 applies a cusp type asymmetric magnetic field G to the crucible 10. In this case, the magnetic field applying means 80 includes an annular upper coil 80a and a lower coil 80b spaced apart from the outer circumferential surface of the thermal insulation means 50 by a predetermined distance. Preferably, the upper coil 80a and the lower coil 80b are installed coaxially with the crucible 10 substantially.

In order to form the asymmetric magnetic field G, for example, different sizes of currents are applied to the upper coil 80a and the lower coil 80b. That is, a larger current is applied to the lower coil 80b than the upper coil 80a. Alternatively, the magnitude of the current applied to the upper coil 80a and the lower coil 80b is the same, and the number of turns of each coil may be adjusted to form an asymmetric magnetic field G. Alternatively, the asymmetric magnetic field G may be formed by simultaneously adjusting the current applied to the coil and the number of turns of the coil.

When the asymmetric magnetic field G is applied to the crucible 10, the horizontal magnetic field component or the vertical magnetic field component at the point 100 where the upper surface of the semiconductor melt SM accommodated in the crucible 10 and the sidewall of the crucible vertically meet each other. The size of is preferably 800G or less. Then, the convection speed of the silicon melt SM may be slowed to delay the crystallization reaction induced on the surface of the crucible 10, and the crucible 10 may be deteriorated to prevent its shape from being deformed. This will be described later through experimental examples.

Preferably, the semiconductor single crystal manufacturing apparatus is used for silicon single crystal growth. In this case, the high temperature semiconductor melt SM accommodated in the crucible 10 is a silicon melt, and the crucible 10 is a quartz crucible. However, the present invention is not limited thereto and may be used in the manufacture of various semiconductor single crystals known in the art. Therefore, the specific components of the crucible and the semiconductor melt accommodated therein may be variously modified depending on the type of semiconductor single crystal to be manufactured.

FIG. 2 shows a simulation of the magnetic field distribution around the silicon melt and the quartz crucible (upper view) and the convection velocity by position of the silicon melt (lower view) when the semiconductor single crystal manufacturing apparatus according to the present invention is used for the production of silicon single crystal It is. In FIG. 2, the left figure shows a case where R (G _lower / G _upper ) is 1.36 and the right figure shows a case where R (G _lower / G _upper ) is 2.3. Reference numeral 90 denotes a ZGP in which the vertical component of the magnetic phase becomes zero.

Referring to FIG. 2, it can be seen that the position of the ZGP 90 increases as the R value increases from 1.36 to 2.3. Increasing the R value means that the magnetic field strength of the lower coil is greater than that of the upper coil. Therefore, it is obvious that the ZGP 90 will gradually move upward as the value of R increases.

After increasing the R value as described above, the strength of the magnetic field was calculated at the bending point A located at the lower end of the sidewall of the quartz crucible 10, and the strength of the magnetic field was increased from 87G to 200G. Accordingly, the convection velocity of the silicon melt is reduced at both the lower curved point A of the quartz crucible sidewall, the outermost point B of the solid-liquid interface, and the quartz crucible bottom point C. Specifically, the convection velocity is reduced from 3.2 cm / s to 2.7 cm / s at point A, from 2.3 cm / s to 2.2 cm / s at point B and from 1.6 cm / s to 1.4 cm / s at point C. In view of the decrease in the speed of convection, it can be seen that the speed decrease is prominent at the bending point A of the quartz crucible 10.

When the convection speed of the silicon melt (SM) is reduced by increasing the R value as described above, it is possible to reduce the rate of crystallization of cristobarite on the surface of the quartz crucible 10. Accordingly, it is possible to suppress the growth of cristobarite to the extent that the surface is peeled off, even in a long time operation environment of 60 hours or more. This effect is clearly confirmed by the following experimental results.

Experimental Example

Comparative Example 1

In a state where no magnetic field was applied, a silicon single crystal having a diameter of 200 mm was grown to 1500 mm for 100 hours by the CZ method. Then, the surface of the side wall, the bend and the bottom of the quartz crucible was photographed. 3 shows the photographs taken in this way. In FIG. 3, (a) is a side wall part photograph, (b) is a curved part photograph, and (c) is a bottom part photograph.

Referring to FIG. 3, it can be seen that a large amount of cristobarite is generated over the entire surface of the quartz crucible due to the absence of a magnetic field, thereby actively crystallizing the stone crucible. The cristobarite surface is peeled off from the quartz crucible during silicon single crystal growth, moved to the solid-liquid interface by convection, and then incorporated into single crystal silicon to act as a determinant of dislocation defects. As a result, the quality of the silicon single crystal is reduced, resulting in a decrease in yield.

Comparative Example 2

In a state in which a symmetric Cusp magnetic field was applied, a silicon single crystal having a diameter of 200 mm was grown to a length of 1200 mm for 87 hours by the CZ method. At this time, the magnetic field strength at the point where the silicon melt and the quartz crucible sidewall vertically met (see 100 in FIG. 1) was 17G, and the bent portion (see FIG. 2A) located at the bottom of the quartz crucible and the outermost point of the solid interface (see FIG. 2). Magnetic field strengths were 62G and 17G, respectively.

Then, the surface and the cross section of the curved portion of the quartz crucible were photographed. 4 shows a photograph thus taken. In FIG. 4, (a) is a surface photograph of the quartz crucible bend, and (b) is a cross-sectional picture of the bend.

Referring to FIG. 4, it can be seen that crystallization of cristobarite occurs in the curved portion of the quartz crucible even when a cusp magnetic field is applied. In addition, as can be seen in Fig. 4 (a), the degree of crystallization of cristobarite was apparent enough to be seen with the naked eye (see the dotted circle). Therefore, since the crystallization of cristobarite cannot be effectively suppressed by the symmetric magnetic field, there is a limit in producing a high quality silicon single crystal.

In addition, when looking at the cross section of the curved part of the quartz crucible, it can be confirmed that the thickness is not constant. This means that the stone crucible deteriorated due to prolonged operation, which deformed the shape. This deformation of the quartz crucible adversely affects the stable convection of the silicon melt. In particular, it is obvious that the degree of deformation of the quartz crucible will increase as the latter part of the silicon single crystal growth process increases. Therefore, the change in the convection pattern of the silicon melt in the second half of the process is likely to be severe, causing a process abnormality such as a flower or a dog-leg. When such process abnormalities are induced, the quality of the silicon single crystal is degraded and the yield is reduced.

Example

According to the present invention, a silicon single crystal having a diameter of 200 mm was grown to a length of 1500 mm for 132 hours while an asymmetric magnetic field with R greater than 1 was applied. At this time, the R value was set to 2.3, the magnetic field strength at the point where the silicon melt surface and the quartz crucible sidewall vertically met (see 100 in FIG. 1) was 66 G, the quartz crucible curved point (see A in FIG. 2) and the solid solution The magnetic field strengths at the outermost point of the interface (see B in FIG. 2) were 200G and 84G, respectively.

Then, a quartz crucible curved surface photograph was taken, and a quartz crucible was crushed to take a cross-sectional photograph of the curved portion and the bottom portion. 5 shows a photograph taken in this way. Fig. 5 (a) shows the surface photograph of the quartz crucible bend, (b) shows the cross section photograph of the bottom of the quartz crucible, and (c) shows the cross section photograph of the quartz crucible bend.

Referring to Figure 5 (a), the crystallization of cristobarite did not proceed to the extent that it is visually confirmed. In contrast to FIG. 4A, the inner surface of the quartz crucible is almost pure white due to little contamination. In addition, although the crystallization of the cristobarite proceeded to some extent, it can be seen that the degree is significantly small. Therefore, the surface peeling of the crastobarite is not substantially generated on the surface of the quartz crucible even in a long operating environment of about 132 hours. In addition, referring to Figure 5 (b) and (c), it can be seen that the shape of the quartz crucible is hardly deformed even in a long time operating environment because the thickness of the quartz crucible curved portion and the bottom portion is uniform.

Comparative Experiment

After the silicon single crystal growth method according to Comparative Examples 1 and 2 described above and the examples were applied to an actual process, the yield was measured. Then the results are summarized in Table 1 below.

TABLE 1

Comparative Example 1 Comparative Example 2 Example Lot number 3 16 12 Charge 150 120 150 Total Lth (cm) 255 1496 1650 cm / run 85 93 138 Yield (%) 57% 78% 92% Average operating time (hr) 97 85 128

In Table 1, 'Lot number' is the number of silicon single crystals grown, 'charge' is the amount of polycrystalline silicon injected into the quartz crucible (unit: kg), 'Total Length' is the total length of the silicon single crystal grown, ' cm / run 'is the average length of each silicon single crystal grown,' Yield 'is the yield, and' operation time 'is the total time of the silicon single crystal growth process.

Referring to Table 1, the application of an asymmetric magnetic field as described in Example 1 delayed the crystallization rate of cristobarite on the surface of the quartz crucible and prevented the morphology of the quartz crucible, resulting in silicon single crystal yield even in a long time operation environment of about 130 hours. It can be confirmed that it is very excellent compared to the Comparative Examples 1 and 2. This result means that the large size of the silicon single crystal can be increased by the increase of the operating time, and the productivity of the single crystal manufacturing process can be maximized by the active introduction of the multi-pull process.

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited thereto and is intended by those skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of equivalents of the claims to be described.

According to the present invention, in the process of manufacturing a semiconductor single crystal having a large diameter of 200 mm or more by using the CZ method, it is possible to effectively suppress the dislocation defects of the semiconductor single crystal due to crystal delamination on the surface of the crucible, thereby enabling the production of high quality semiconductor single crystal. .

According to another aspect of the present invention, it is possible to prevent the morphological deformation of the quartz crucible even in a long time operating environment, it is possible to increase the capacity of the crucible. Therefore, the large diameter of the semiconductor single crystal is possible, and the productivity (yield) of the semiconductor single crystal manufacturing process can be maximized by the active introduction of the multi-pull process.

According to another aspect of the present invention, by extending the life of the crucible, which is a key component of the semiconductor single crystal growth apparatus using the CZ method, it is possible to reduce the production cost of the semiconductor single crystal and immediately apply it to production even with a simple design change of the existing equipment. There is an economic advantage that this is possible.

Claims (11)

In the method for manufacturing a semiconductor single crystal using the Czochralski method in which a seed crystal is immersed in a semiconductor melt contained in a crucible and then the seed crystal is gradually raised to grow a semiconductor single crystal. Apply a non-symmetrical magnetic field with a higher magnetic field strength than the upper part to the crucible based on the zero Gauge Plane (ZGP) whose vertical component is zero.The magnetic field horizontal component at the point where the surface of the semiconductor melt and the sidewall of the crucible meet vertically or The vertical single component is 800G or less, The semiconductor single crystal manufacturing method characterized by the above-mentioned. The method of claim 1, Single crystal growth operation time is 60 hours or more, The semiconductor single crystal manufacturing method characterized by the above-mentioned. The method of claim 1,  Wherein the crucible is a quartz crucible and the semiconductor melt is a silicon melt. In the apparatus for manufacturing a semiconductor single crystal using the Czochralski method comprising a crucible, crucible rotating means and pulling means for pulling a single crystal from a semiconductor melt contained in the crucible by seed crystals, The asymmetric magnetic field, which is installed around the crucible and has a higher magnetic field intensity than the upper portion, is applied to the crucible based on a zero gauge plane (ZGP) whose vertical component is zero, but the surface of the semiconductor melt and the sidewall of the crucible are perpendicular to each other. And a magnetic field applying means for applying a magnetic field having a magnetic field horizontal component or a vertical component of 800 G or less at a point meeting each other. The method of claim 4, wherein  The magnetic field applying means includes an upper coil and a lower coil spaced apart by a predetermined distance, and the upper coil and the lower coil are disposed coaxially with the crucible. The method of claim 5, The asymmetric magnetic field is a semiconductor single crystal manufacturing apparatus, characterized in that the Cusp type magnetic field. According to claim 6, wherein the magnetic field applying means, The number of turns of the upper coil and the lower coil is the same, but more current is applied to the lower coil than the upper coil; Applying a current having the same magnitude to the upper coil and the lower coil, but controlling a larger number of turns of the lower coil than the upper coil; or And forming the asymmetric magnetic field by simultaneously controlling the strength of the current and the number of turns applied to the upper coil and the lower coil. The method of claim 4, wherein Wherein the crucible is a quartz crucible and the semiconductor melt is a silicon melt. The semiconductor single crystal manufacturing apparatus according to claim 4, wherein the single crystal growth operation time is 60 hours or more. delete delete

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