KR100906281B1 - Heat shield structure for growing silicon single crystal ingot and grower using the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat shield structure provided in a device for growing silicon single crystal ingots by the Czochralski method, wherein a portion is disposed at a point close to the interface of the silicon melt, and gradually becomes an axial direction from the center of the single crystal ingot to the edge portion. A lower heat shield for controlling the temperature gradient to be large; And a part of which is disposed above the lower heat shield so as to be spaced apart from the lower heat shield, and is controlled to gradually decrease in the axial temperature gradient from the center of the single crystal ingot to the edge portion, resulting in a temperature gradient deviation by the lower heat shield. Disclosed is a heat shield structure including;

Czochralski method, single crystal ingot, heat shield, temperature gradient, melt gap, boronkov theory

Description

Heat shield structure for growing silicon single crystal ingot and grower using 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 and 2 are cross-sectional views showing a heat shield structure of a silicon single crystal ingot growth apparatus according to the prior art.

Figure 3 is a cross-sectional view showing a heat shield structure of the silicon single crystal ingot growth apparatus according to an embodiment of the present invention.

FIG. 4 is a graph illustrating the G value distribution provided by the heat shield structure of FIG. 3.

5 is a table showing the results of measuring the G value for each point of the silicon single crystal ingot according to the embodiment and the comparative example of the present invention.

FIG. 6 is a distribution diagram illustrating a change in silicon single crystal pulling speed and a crystal defect distribution when a heat shield structure according to the present invention is applied. FIG.

FIG. 7 is a distribution diagram illustrating a change in silicon single crystal pulling speed and a crystal defect distribution when a heat shield structure according to the related art is applied. FIG.

<Description of main reference numerals in the drawings>

10: quartz crucible 11: single crystal ingot

15: heat shield structure 15a: lower heat shield

15b: top heat shield

The present invention relates to a heat shield structure of a silicon single crystal ingot growth apparatus and a silicon single crystal ingot growth apparatus using the same, and more particularly, to a heat shield structure having a structure capable of realizing a large and uniform temperature gradient in a radial direction during single crystal growth. It relates to a silicon single crystal ingot growth apparatus using the same.

As semiconductor device processes are increasingly micronized, even tens of nanoscale crystal defects are causing device yield deterioration. Accordingly, there is an increasing trend of semiconductor device makers using wafers whose crystal defects are controlled as semiconductor substrates.

However, according to Voronkov's theory, the process margin of the so-called defect-free single crystal production is affected by the radial vertical temperature gradient, so there is a difficulty in realizing a large and uniform temperature gradient in the radial direction.

The Voronkov Theory means that the dominant point defect in a crystal is vacancy-rich if the V / G value is greater than a certain threshold and the V / G value is less than any threshold. The theory is that it becomes interstitial-rich. Where V is the single crystal pulling rate and is the convection parameter of point defects in the silicon single crystal. In addition, G is the instantaneous axial vertical temperature gradient near the crystal melt interface (hereinafter referred to as 'temperature gradient') and is the diffusion parameter of point defects due to the temperature gradient in the crystal.

When G is relatively large, the thermodynamic point defect concentration gradient is also largely formed by a large temperature gradient, so that the point defect diffusion in the crystal direction increases. However, since the diffusion mobility of the interstitial is larger than the vacancy, the dominant point defect becomes the interstitial. On the other hand, when V is large, the state of vacancy concentration higher than interstitial is maintained as it is during crystallization due to convection due to single crystal pulling (because the effect by G is small). That is, if the V / G value is greater than a certain threshold, vacancy-rich is formed, and if the V / G value is less than a certain threshold, interstitial-rich is formed.

In the single crystal ingot, heat transfer is performed through thermal conduction by temperature gradient and heat is released through the surface of the ingot. Therefore, the temperature gradient in the single crystal ingot can be controlled by effectively controlling the heat release at the ingot surface. For this purpose, the single crystal ingot growth apparatus is generally provided with a heat shield. Related arts related thereto include Korean Patent Registration No. 374703, Korean Patent Registration No. 411571, and US Patent Registration No. 6,527,859.

As shown in FIGS. 1 and 2, the heat shield 12 is disposed between the single crystal ingot 11 and the quartz crucible 10 to absorb heat emitted from the interface of the silicon melt SM contained in the quartz crucible 10. It insulates and appropriately controls the temperature distribution of the silicon melt (SM) required for the ingot to grow and the temperature distribution of the high temperature portion of the ingot. In FIGS. 1 and 2, the heat shields 12 of A and B correspond to elements provided in different growth apparatuses, but are shown in the same drawing for convenience of understanding.

In order to improve the structure of the heat shield, conventionally, a method of controlling the G value by designing a small or large size of the heat shield has been used. However, as shown in FIG. 1, the heat shield 12 having a relatively thin size may increase the G value, but there is a problem of deterioration in the radial uniformity. On the contrary, as shown in FIG. The heat shield 12 has a good radial uniformity but has a problem in that the G values of the central portion 13 and the edge portion 14 become small. In addition, in the case of configuring a single heat shield 12, no matter how melt-gap control is performed, since the G value appears at the (1/2) R to (2/3) R point in the radial direction, There is a limit that the G value must be nonuniform.

On the other hand, as the heat shield is closer to the solid-liquid interface, that is, the smaller the melt gap, the temperature gradient of the ingot edge portion is larger than that of the central portion, as shown in FIG. As the heat shield moves away from the liquid-liquid interface, the temperature gradient at the center of the ingot is larger than the edge portion.

The present invention was conceived in view of the above, a two-stage heat shield structure that can realize a large and uniform temperature gradient throughout the radial direction of the ingot by increasing the temperature gradient at the center and the edge of the silicon single crystal ingot at the same time; An object of the present invention is to provide a silicon single crystal ingot growth apparatus using the same.

In order to achieve the above object, the present invention provides a heat shield having a two-stage structure in which a lower heat shield for controlling a temperature gradient for the edge portion of the ingot and an upper heat shield for controlling the temperature gradient for the center of the ingot are combined. It starts.

That is, according to one aspect of the present invention, in the heat shield structure provided in the apparatus for growing a silicon single crystal ingot by the Czochralski method, a part is disposed at a point close to the interface of the silicon melt, and from the center of the single crystal ingot A lower heat shield that controls the gradual temperature gradient gradually toward the edge portion; And a part of which is disposed above the lower heat shield so as to be spaced apart from the lower heat shield, and is controlled to gradually decrease in the axial temperature gradient from the center of the single crystal ingot to the edge portion, resulting in a temperature gradient deviation by the lower heat shield. An upper heat shield structure is provided that includes a top heat shield to compensate.

Preferably, the lower heat shield has an opposite bottom surface at a position proximate to the silicon melt, and an inclined surface connected to the bottom surface and inclined obliquely toward the single crystal ingot, wherein the upper heat shield is the inclined surface of the lower heat shield. A bottom surface spaced apart from the bottom surface and an inclined surface that is connected to the bottom surface and inclined obliquely toward the single crystal ingot.

The lower heat shield and the upper heat shield may be composed of any one or two or more selected from the group consisting of carbon felt, graphite, SiC coated graphite, and Moly.

It is preferable that the melt gap of the upper heat shield does not exceed the diameter of the single crystal ingot.

According to another aspect of the present invention, a quartz crucible having an internal space for accommodating silicon melt, a heater installed to surround the quartz crucible, and heating the quartz crucible, a silicon single crystal ingot grown from the silicon melt and the quartz A device for growing a silicon single crystal ingot by a Czochralski method, comprising a heat shield structure disposed between crucibles and blocking heat radiated from the silicon single crystal ingot, wherein the heat shield structure is formed at an interface of the silicon melt. A lower heat shield disposed at an adjacent point, the lower heat shield controlling the gradual temperature gradient gradually from the center of the single crystal ingot to the edge; And a part of which is disposed above the lower heat shield so as to be spaced apart from the lower heat shield, and is controlled to gradually decrease in the axial temperature gradient from the center of the single crystal ingot to the edge portion, resulting in a temperature gradient deviation by the lower heat shield. Provided is a silicon single crystal ingot growth apparatus comprising a; top heat shield to compensate.

The temperature distribution of the single crystal ingot corresponding to the nearest part with the single crystal ingot in the lower heat shield is 1050 to 1250 ° C., and the temperature of the single crystal ingot corresponding to the nearest part with the single crystal ingot in the upper heat shield. It is preferable that distribution is 800-1000 degreeC.

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 specification and claims should not be construed as having a conventional or dictionary meaning, 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 embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

3 is a cross-sectional view schematically showing a heat shield structure of a silicon single crystal ingot growth apparatus according to an embodiment of the present invention.

Although not shown in detail in the drawing, the silicon single crystal ingot growth apparatus includes known components for growing a silicon single crystal ingot by the Czochralski method. That is, the silicon single crystal ingot growth apparatus is provided with a chamber, and inside the chamber is filled with a quartz crucible 10 containing silicon melt (SM) and the outer peripheral surface of the crucible support made of graphite. At this time, the crucible support is fixedly installed on the rotating shaft, and the rotating shaft is rotated by the driving means to raise the crucible 10 while rotating the solid-liquid interface to maintain the same height. The crucible support is surrounded by a cylindrical heater at predetermined intervals. The heater is installed on the side of the quartz crucible to melt a high-purity polycrystalline silicon mass loaded in the quartz crucible 10 into a silicon melt SM. In addition, a heat shield structure 15 is installed between the single crystal ingot 11 and the quartz crucible 10 to block the heat flow radiated upward from the silicon melt SM to prevent heat. Preserve In addition, a pulling means for winding a cable is provided in the upper part of the chamber, and a lower crystal is provided in the lower part of the cable to grow the single crystal ingot 11 while contacting and pulling the silicon melt SM in the quartz crucible. The pulling means rotates while pulling up the cable during growth of the single crystal ingot 11, wherein the single crystal ingot 11 is rotated about the same axis as the rotation axis of the quartz crucible 10 and is opposite to the rotation direction of the quartz crucible 10. Or pull up while rotating in the same direction. In the upper part of the chamber, an inert gas such as argon (Ar), neon (Ne), and nitrogen (N) is supplied to the grown single crystal ingot 11 and the silicon melt SM, and the inert gas used is the lower part of the chamber. Eject through.

In particular, the heat shield structure 15 provided in accordance with the present invention is disposed close to the upper side of the silicon melt (SM) SM to participate in the temperature gradient control of the edge portion of the single crystal ingot 11, and the lower heat It is comprised by the two-stage heat shield which consists of the upper heat shield 15b arrange | positioned above the shield 15a and is involved in the temperature gradient control of the center part of the single crystal ingot 11. As shown in FIG.

The lower heat shield 15a has an opposite bottom face 16 at a position proximate to the silicon melt SM and an inclined face 17 subsequent to the bottom face 16. The inclined surface 17 extends from the closest surface to the single crystal ingot 11 in the lower heat shield 15a but is inclined obliquely toward the single crystal ingot 11. At this time, the inclined surface 17 is formed in multiple stages having different inclination angles, or are formed in a single inclination angle. In order to increase the temperature gradient of the ingot edge portion, the smaller the melt gap of the lower heat shield 15a is preferable.

The upper heat shield 15b includes a bottom surface 18 spaced apart from the inclined surface 17 of the lower heat shield 15a by a predetermined distance, and an inclined surface 19 connected to the bottom surface. Like the inclined surface 17 of the lower heat shield 15a, the inclined surface 19 extends from the closest surface with the single crystal ingot 11 and has an inclined shape obliquely toward the single crystal ingot 11, and has different inclination angles. It is formed in multiple stages or in a single tilt angle.

The upper heat shield 15b is preferably made of at least one material of carbon felt, graphite, SiC coated graphite, or Moly to promote heat release from the single crystal ingot or partially insulate it. In view of the heat transfer distribution and temperature gradient from the solid-liquid interface, it is preferable that the melt gap of the upper heat shield 15b does not exceed the diameter of the single crystal ingot 11. Therefore, the position of the upper heat shield 15b may be designed to be 150mm, 200mm, 300mm, etc. corresponding to the diameter of the commercially available silicon single crystal ingot.

The main heat transfer path from the solid-liquid interface by the temperature gradient control action by the lower heat shield 15a and the upper heat shield 15b has a G value that is substantially equal to each other in the ingot center, R / 2 and the edge portion as shown in FIG. Distributed to have.

The temperature distribution of the single crystal ingot 11 corresponding to the closest portion with the single crystal ingot 11 in the lower heat shield 15a is preferably 1050 to 1250 ° C, and the single crystal ingot (15b) in the upper heat shield 15b. It is preferable that the temperature distribution of the single crystal ingot 11 corresponding to the nearest part with 11) is 800-1000 degreeC. Such a corresponding structure can maximize the point defect diffusion effect in the high temperature region, and can provide a secondary defect formation suppression effect, particularly at around 1150 ℃ and around 850 ℃.

FIG. 4 shows the G value distribution provided by the heat shield structure of FIG. 3. In the figure, the dotted line graph shows the G value distribution by the lower heat shield 15a, and the dashed-dot line graph shows the G value distribution by the upper heat shield 15b. As shown in the figure, the difference in the axial temperature gradient is simultaneously compensated by the lower heat shield 15a and the upper heat shield 15b. As a result, the G value is improved as a solid composite graph and substantially from the ingot center to the edge portion. G value is distributed uniformly.

In the general growth interface (slightly single concave or double concave), the heat dissipation at the crystal center is not smoother than the edge, so the G value tends to increase from the center to the edge. However, since the temperature gradient distribution at the growth interface is affected by the heat transfer path, the G value of the center portion can be increased larger than the edge portion through the upper heat shield 15b spaced from the lower heat shield 15a. In this case, since the G value increases toward the center of the ingot according to the heat balance equation, the temperature gradient difference due to the heat transfer path in the crystal is compensated.

k _S G _S = k _L G _L + L _f V

k _S : Solid (single crystal) heat transfer coefficient, G _S : Solid (single crystal) temperature gradient

k _L : Liquid (melt) heat transfer coefficient, G _L : Liquid (melt) temperature gradient

L _f : latent heat of crystallization, V: growth rate

5 is a table showing the results of measuring the G value for each point of the silicon single crystal ingot according to the embodiment and the comparative example of the present invention. Referring to the figure, the comparative examples 1 to 4 the embodiment of the present invention, unlike (A-D in Fig. 1 and 2) is the ingot center, R / 2 and the edge of the G value of the deviation (G _{min - max)} of 0.1 to It can be seen that the appearance is very small as 0.2.

Figure 6 shows the change in silicon single crystal pulling speed and the defect distribution of the crystal when the heat shield structure according to the present invention is applied, Figure 7 shows the change and crystallization of silicon single crystal pulling speed when the heat shield structure according to the prior art is applied The defect distribution of is shown. Referring to the drawings, the process margin M of the defect-free regions Pv and Pi of the single crystal ingot to which the heat shield structure of the present invention shown in FIG. 6 is applied is shown in FIGS. 7A to 7C. Compared to the process margin (M) of the technology it can be seen that the increase rate is significantly increased.

As described above, the heat shield structure 15 provided according to the present invention is composed of a two-stage heat shield having an appropriate level gap to minimize the temperature gradient variation on the single crystal ingot growth interface. That is, the lower heat shield 15a positioned below the heat shield structure 15 is disposed on the silicon melt SM and surrounds the growing single crystal ingot to maintain the temperature distribution of the silicon melt SM. Effectively controlling the axial temperature gradient with respect to the edge portion of the single crystal ingot, and the upper heat shield 15b located on the top of the heat shield structure 15 promotes heat emission from the single crystal ingot 11 and Effectively control the axial temperature gradient with respect to the center.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

According to the present invention, the axial temperature gradients of the center, R / 2, and edge portions of the ingot can be maintained substantially constant along the radial direction of the ingot, thereby making it possible to manufacture silicon wafers having the same characteristics over the entire wafer surface.

In addition, since the pulling speed can be improved during the growth of the silicon single crystal ingot, productivity is improved and manufacturing cost can be reduced.

Claims (9)

In the heat shield structure provided in the apparatus for growing a silicon single crystal ingot by the Czochralski method, A lower heat shield disposed above the silicon melt and controlling the axial temperature gradient to gradually increase from the center of the single crystal ingot to the edge portion; And A part is disposed above the lower heat shield so as to be spaced apart from the lower heat shield, and is controlled to gradually decrease in the axial temperature gradient from the center of the single crystal ingot to the edge portion, thereby reducing the temperature gradient deviation caused by the lower heat shield. A top heat shield to compensate; The material of the upper heat shield is any one selected from the group consisting of carbon felt, graphite, SiC coated graphite and Moly (Moly). The method of claim 1, The lower heat shield has a bottom facing the silicon melt and an inclined surface that is inclined at an angle toward the single crystal ingot while being connected to the bottom; And the upper heat shield has a bottom spaced apart from the inclined surface of the lower heat shield and an inclined surface connected to the bottom surface and inclined obliquely toward a single crystal ingot. delete In the heat shield structure provided in the apparatus for growing a silicon single crystal ingot by the Czochralski method, A lower heat shield disposed above the silicon melt and controlling the axial temperature gradient to gradually increase from the center of the single crystal ingot to the edge portion; And A part is disposed above the lower heat shield so as to be spaced apart from the lower heat shield, and is controlled to gradually decrease in the axial temperature gradient from the center of the single crystal ingot to the edge portion, thereby reducing the temperature gradient deviation caused by the lower heat shield. A top heat shield to compensate; And wherein the melt gap of the upper heat shield does not exceed the diameter of the single crystal ingot. The silicon crucible is provided between a quartz crucible having an internal space accommodating the silicon melt, a heater installed to surround the quartz crucible, and a heater heating the quartz crucible, a silicon single crystal ingot grown from the silicon melt and the quartz crucible. An apparatus for growing a silicon single crystal ingot by a Czochralski method, comprising a heat shield structure that blocks heat radiated from an interface, The heat shield structure, A lower heat shield disposed above the silicon melt and controlling the axial temperature gradient to gradually increase from the center of the single crystal ingot to the edge portion; And A part is disposed above the lower heat shield so as to be spaced apart from the lower heat shield, and is controlled to gradually decrease in the axial temperature gradient from the center of the single crystal ingot to the edge portion, thereby reducing the temperature gradient deviation caused by the lower heat shield. A top heat shield to compensate; The material of the upper heat shield is silicon single crystal ingot growth apparatus comprising any one selected from the group consisting of carbon felt, graphite, SiC coated graphite and Moly (Moly). The method of claim 5, The lower heat shield has a bottom facing the silicon melt and an inclined surface that is inclined at an angle toward the single crystal ingot while being connected to the bottom; And the upper heat shield has a bottom spaced apart from the inclined surface of the lower heat shield and an inclined surface connected to the bottom surface and inclined obliquely toward a single crystal ingot. delete The silicon crucible is provided between a quartz crucible having an internal space accommodating the silicon melt, a heater installed to surround the quartz crucible, and a heater heating the quartz crucible, a silicon single crystal ingot grown from the silicon melt and the quartz crucible. An apparatus for growing a silicon single crystal ingot by a Czochralski method, comprising a heat shield structure that blocks heat radiated from an interface, The heat shield structure, A lower heat shield disposed above the silicon melt and controlling the axial temperature gradient to gradually increase from the center of the single crystal ingot to the edge portion; And A part is disposed above the lower heat shield so as to be spaced apart from the lower heat shield, and is controlled to gradually decrease in the axial temperature gradient from the center of the single crystal ingot to the edge portion, thereby reducing the temperature gradient deviation caused by the lower heat shield. A top heat shield to compensate; The silicon single crystal ingot growth apparatus, characterized in that the melt gap (Melt-Gap) of the upper heat shield does not exceed the diameter of the single crystal ingot. The silicon crucible is provided between a quartz crucible having an internal space accommodating the silicon melt, a heater installed to surround the quartz crucible, and a heater heating the quartz crucible, a silicon single crystal ingot grown from the silicon melt and the quartz crucible. An apparatus for growing a silicon single crystal ingot by a Czochralski method, comprising a heat shield structure that blocks heat radiated from an interface, The heat shield structure, A lower heat shield disposed above the silicon melt and controlling the axial temperature gradient to gradually increase from the center of the single crystal ingot to the edge portion; And A part is disposed above the lower heat shield so as to be spaced apart from the lower heat shield, and is controlled to gradually decrease in the axial temperature gradient from the center of the single crystal ingot to the edge portion, thereby reducing the temperature gradient deviation caused by the lower heat shield. A top heat shield to compensate; The temperature distribution of the single crystal ingot at the point opposite to the portion closest to the single crystal ingot among the respective portions of the lower heat shield is 1050 to 1250 ° C., And a temperature distribution of the single crystal ingot at a point of the portions of the upper heat shield that is opposite to the portion closest to the single crystal ingot is 800 to 1000 ° C.

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