KR101105547B1 - Heater used for manufacturing single crystal, Apparatus and Method of manufacturing single crystal using the same - Google Patents

Abstract

The present invention discloses a graphite heater for producing a single crystal, an apparatus and a method for producing a single crystal comprising the same. The graphite heater according to the present invention is a graphite heater consisting of a cylindrical heater wall for receiving a heating object, wherein the heater wall is a maximum heating part, a stabilizing heating part, and a local heat generating a step on the outside of the wall while going from the bottom to the upper part. The unit is sequentially provided, wherein the maximum heat generating unit provides a heat generation amount of 40% or more based on the total heat generation amount of the heater, the local heat generating unit is characterized in that providing a heat generation amount of 15% or more based on the total heat generation amount of the heater.

By using the graphite heater according to the present invention, it is possible to shorten the time required for the polycrystalline melting process and the stabilization process of the melt, to suppress the shape deformation of the quartz crucible and the generation of crystalline precipitates during polycrystalline melting, and Emissions of by-product gases are easy and the convection is activated near the melt surface to increase the oxygen concentration in the single crystal, increase the single crystal pulling rate and increase the flawless process margin for V / G.

Czochralski method, graphite heater, calorific value, local heat generation, single crystal

Description

Graphite heater for single crystal production, single crystal manufacturing apparatus and method including the same {Heater used for manufacturing single crystal, Apparatus and Method of manufacturing single crystal using the same}

The present invention relates to a graphite heater used in a single crystal production apparatus using the Czochralski method (abbreviated as CZ method), and a single crystal growth method and apparatus using the same.

The single crystal used as a substrate of a semiconductor element is mainly manufactured by CZ method. Here, examples of the single crystal include silicon single crystal. When manufacturing single crystal by the CZ method, the single crystal manufacturing apparatus 10 like FIG. 1 is used.

The single crystal manufacturing apparatus 10 includes a member for melting a polycrystalline (eg, single crystal silicon) raw material, a member for blocking heat, a member for pulling up a single crystal, and the like, which are installed in the main chamber 11. do.

The main chamber 11 is connected to the chamber 12 located in the upper portion, and the single crystal pulling means for pulling up the single crystal 13 by using a wire 14 having a seed crystal 22 above the chamber 12 ( Not shown) is installed.

In the main chamber 11, a quartz crucible 16 accommodating the melt 15 and a graphite crucible 17 supporting the quartz crucible 16 are provided, and the crucibles 16, 17 are driven by a driving mechanism. Is supported by the shaft 18, which is rotated and raised and lowered by the " shown " The crucibles 16 and 17 driving mechanism operates to raise the crucibles 16 and 17 by the liquid level lowered to compensate for the lowering of the liquid level of the melt 15 due to the pulling of the single crystal 13.

A graphite heater 19 is arranged around the crucibles 16 and 17. The graphite heater 19 heats the crucibles 16 and 17 by resistance heating to melt the polycrystalline raw material. The outer side of the graphite heater 19 is provided with a heat insulating member 20 surrounding the graphite heater 19. The heat insulating member 20 prevents heat generated from the graphite heater 19 from being directly radiated to the main chamber 11.

The chamber 12 is provided with a cooling cylinder 23 for cooling the raised single crystal. Inert gas is supplied to the inner space of the cooling cylinder 23. Inert gas enhances the cooling effect of the single crystal. The lower portion of the cooling cylinder 23 is provided with a heat shield 25 surrounding the single crystal. The heat shield 25 blocks the radiant heat emitted from the melt surface to prevent radiant heat from being applied to the single crystal 13. In addition, the heat shield 25 reflects radiant heat emitted from the single crystal surface to prevent sudden cooling of the single crystal surface.

The conventional structure of the graphite heater 19 is as shown in Figs. 2 is a front view of the graphite heater 19, and FIG. 3 is a rear view of the graphite heater 19. The right side of each figure shows the cross section along the AA 'line of the graphite heater 19 together.

2 and 3, the graphite heater 19 has a cylindrical shape and mainly consists of isotropic graphite. The graphite heater 19 includes a terminal portion 27 and a heat generating portion 28. The terminal portion 27 provides a path through which the operating current is drawn in and output and firmly fixes the graphite heater 19 to the bottom of the main chamber 11. The heat generating unit 28 generates resistance heat by the current flowing through the terminal unit 27 and applies radiant heat to the crucibles 16 and 17. The heat generating unit 28 includes an upper slit 29 cut from the top to the bottom and a lower slit 30 cut from the bottom to the top. The upper slit 29 and the lower slit 30 increase the length of the current path and reduce the cross-sectional area of the current path to maximize the resistance of the heat generator 28. When the resistance of the heat generating unit 28 is increased by the slits 29 and 30, the amount of heat generated by the graphite heater 19 also increases by the resistance increase.

The power supplied to the graphite heater 19 is the highest in the melting step of the polycrystalline raw material (hereinafter referred to as melting step). The maximum heat generating portion of the graphite heater 19 corresponds to the side wall positions of the crucibles 16 and 17 as the center portion O of the heat generating portion 28. Therefore, in the melting process, the most heat is applied to the sidewalls of the quartz crucible 16. When heat is concentrated on the sidewall of the quartz crucible 16, the following problem occurs.

The heat applied from the graphite heater 19 is concentrated on the sidewall of the quartz crucible 16, so that the degree of softening of the sidewall of the quartz crucible 16 is relatively larger than that of the other parts. As a result, the softened quartz flows down by gravity as it goes to the second half of the melting process, resulting in a slight thickness variation on the quartz crucible 16 sidewalls. In some cases, the upper end of the sidewall of the quartz crucible 16 is bent downward to deform the crucible shape. In this case the convection symmetry in the melt is disturbed, resulting in poor quality of the single crystal and reduced yield.

In addition, during the melting process, a crystallization reaction is induced between the quartz crucible 16 and the melt to form crystalline precipitates on the inner wall of the quartz crucible 16. The crystalline precipitate is likely to be peeled off at the point where the quartz crucible 16 is softened. Since the sidewall of the quartz crucible 16 is softer than other portions, the sidewall of the quartz crucible 16 serves as a release source of the crystalline precipitate. The crystalline precipitate separated from the quartz crucible 16 is transferred to the solid-liquid interface by convection of the melt in the single crystal growth process and flows into the single crystal. Crystalline precipitates introduced into single crystals are the cause of dielectric degradation.

Further, if heat is concentrated on the sidewall of the quartz crucible 16 in the melting process, there is a possibility that the quartz crucible 16 may be damaged in the process of melting the polycrystalline raw material. That is, when heat is concentrated on the sidewalls of the quartz crucible 16, melting starts from the raw material near the sidewalls of the quartz crucible 16. The melt formed by melting of the single crystal raw material is moved to the lower part of the quartz crucible 16 by convection and gravity to dissolve the surrounding polycrystalline raw material. In this process, the polycrystal at the center of the quartz crucible 16 may suddenly sink toward the sidewall of the quartz crucible 16. In this case, the melted phenomenon of the melt or physical damage of the quartz crucible 16 may occur.

In addition, when heat is concentrated on the sidewall of the quartz crucible 16 during the melting process, the melting process time is increased because the gas generated during the melting process is not smoothly discharged. That is, the gas generated in the melting process is present in the melt in the form of bubbles, and then moved to the surface of the melt by convection and then discharged to the outside. However, the polycrystalline raw material under the quartz crucible 16 is indirectly fused through contact with the melt moving in natural convection, rather than being directly melted by the heat transferred from the graphite heater 19. The gas generated during indirect melting takes a long time to move to the surface of the melt and discharge to the outside, thereby increasing the melting process time.

Therefore, in the technical field to which the present invention belongs, research and development are continuously made to solve the above-mentioned problems by locally improving the structure of the graphite heater to improve the calorific value distribution.

The present invention was devised to solve the above-mentioned problems of the prior art, and it is possible to increase the stability of the melting process, to shorten the melting process and the stabilization process time, and to increase the oxygen concentration of the single crystal in the single crystal growth process and to increase the pulling speed. It is an object of the present invention to provide a graphite heater, a single crystal manufacturing apparatus and method including the same, which can increase the productivity and yield of a single crystal by enabling the same.

The graphite heater according to the present invention for achieving the above technical problem is a graphite heater made of a cylindrical heater wall for receiving a heating object, the heater wall is a maximum heating portion formed by placing a step on the outside of the wall going from the bottom to the top And a stabilizing heating part and a local heating part sequentially, wherein the maximum heating part provides a calorific value of 40% or more based on the total calorific value of the heater, and the local heating part provides a calorific value of 15% or more based on the total calorific value of the heater. It is characterized by.

Single crystal manufacturing apparatus according to the present invention for achieving the above technical problem, a quartz crucible in which the melt of the polycrystalline raw material is accommodated; A graphite crucible supporting the shape of the quartz crucible; It is provided around the graphite crucible, and the quartz crucible is heated above the melting temperature of the polycrystalline raw material, and is provided with a maximum heating part, a stabilizing heating part, and a local heating part formed with a step on the outer wall of the heater wall while going from the lower part to the upper part. A graphite heater in which the maximum heat generating portion provides 40% or more of the total heat generation amount and the local heat generating portion provides 15% or more of the total heat generation amount; Crucible driving means for rotating and raising / lowering the graphite crucible; And single crystal pulling means for immersing the seed crystal attached to the wire in the melt contained in the quartz crucible and then pulling the single crystal upward through the solid-liquid interface.

According to the present invention, when the length of the graphite heater is L, it is preferable that the maximum heating part has a length of 20% to 30% L, and the local heating part has a length of 10% to 20% L.

Optionally, the stabilizing heating part includes a first stabilizing heating part and a second stabilizing heating part having different steps. In this case, it is preferable that the first stabilized heat generating portion is in contact with the maximum heat generating portion and the heat generation amount is larger than that of the second stabilized heat generating portion.

Preferably, the heater wall is a part of the upper slit that is cut while going from the upper end to the lower part and the lower slit that is spaced apart from the upper slit by the predetermined distance from the lower end to the upper part, and partially cut in a repeating unit to perform a zigzag current flow path. Have

Preferably, the length of the maximum heating portion, the stabilizing heating portion and the local heating portion, the local heating portion corresponds to the height of the melt surface at the first position condition that the bottom bottom of the quartz crucible is lower than the center of the maximum heating portion, In the second positional condition where the bottom bottom is higher than the center of the maximum heating part, the center of the local heating part is designed to be located at 0.7 to 0.85 h based on the height h of the melt.

Preferably, the bottom bottom of the quartz crucible in the first position condition is located 10 to 25 mm lower than the center of the maximum heating portion, and the bottom bottom of the quartz crucible in the second position condition is 20 to 30 mm than the center of the maximum heating portion. It is located at a high point.

The single crystal manufacturing apparatus according to the present invention may further include a magnetic field applying means for applying a cusp magnetic field so that ZGP is located at 0.7 to 0.85h based on the height h of the melt.

Single crystal manufacturing method according to the present invention for achieving the above technical problem, the step of loading a polycrystalline raw material in a quartz crucible; A maximum heating portion, a stabilizing heating portion and a local heating portion formed by stepping on the outer wall of the heater wall while going from the lower portion to the upper portion, wherein the maximum heating portion is 40% or more of the total heat generation amount, and the local heating portion is 15% or more of the total heat generation amount. Providing a graphite heater around the quartz crucible to provide a; Adjusting the height of the quartz crucible under a first positional condition in which a bottom bottom of the quartz crucible is lower than a center of the maximum heating part; Operating the graphite heater to melt a polycrystalline raw material in a quartz crucible; Adjusting the height of the quartz crucible under a second positional condition where a bottom bottom of the quartz crucible is higher than a center of the maximum heating part; And stabilizing the melt and immersing the seed crystal in the melt and then pulling the single crystal through the solid-liquid interface.

According to the present invention, it is possible to minimize the thermal damage applied to the quartz crucible in the melting process of the polycrystalline raw material, and to reduce the delamination factor of the crystalline precipitates to suppress the occurrence of dielectric dislocation in the single crystal. In addition, since the maximum heat generating portion is located at the bottom of the heater, the power of the graphite heater can be enhanced, thereby reducing the time required for the melting process. In addition, it is possible to increase the oxygen concentration flowing into the single crystal by activating forced convection and natural convection near the solid-liquid interface and increasing the vertical temperature gradient of the solid-liquid interface, thereby increasing the flawless pulling rate. In addition, the temperature variation in the horizontal direction of the solid-liquid interface can be reduced to increase the defect free process margin for V / G. According to the present invention, it is possible to produce a high quality single crystal with easy BMD control with high yield and productivity.

Hereinafter, preferred 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.

4 and 5 are a front view and a rear view of the graphite heater for producing a single crystal according to an embodiment of the present invention, respectively. On the right side of each figure is shown a cross-sectional view along the line B-B '.

4 and 5, the graphite heater 40 according to the embodiment of the present invention is formed of a cylindrical heater wall 41 in which an inner space in which a heating target can be accommodated is defined. For example, the heating target is a quartz crucible provided in the single crystal manufacturing apparatus using the CZ method. The heater wall 41 includes a maximum heating part 42, a stabilizing heating part 43, and a local heating part 44 formed by a step of the wall outer wall while going from the bottom to the top.

The maximum heating part 42 is a heater section that provides a heat generation amount of 40% or more based on the total heat generation amount of the graphite heater 40, and the local heat generation unit 44 is based on the total heat generation amount of the graphite heater 40. A heater section providing a calorific value of more than%, the stabilization heating unit 43 is a heater section providing less than 45% of the heating value based on the total calorific value of the graphite heater 40.

As the step height of each of the heat generating parts 42, 43, 44 increases, the cross-sectional area of the heater through which current flows decreases and the resistance increases by that amount. Since the step of each heat generating unit increases in the order of stabilization heat generating unit 43, local heat generating unit 44, and maximum heat generating unit 42, the resistance magnitude of each heat generating unit 42, 43, 44 also increases in the same order.

Although not shown in the drawings, the stabilizing heating unit 43 may be classified into a first stabilizing heating unit and a second stabilizing heating unit having different steps in some cases. In this case, it is preferable that the first stabilized heat generating portion is in contact with the maximum heat generating portion, and the step difference is greater than that of the second stabilized heat generating portion, so that the heat generation amount is larger than that of the second stabilized heat generating portion.

The heater wall 41 is partially cut by using the upper slit 45 and the lower slit 46 as a repeating unit to have a zigzag current flow path. The upper slit 45 partially cuts the heater wall 41 while going from the upper end of the heater wall 41 to the lower portion. The lower slit 46 partially cuts the heater wall 41 while going from the lower end of the heater wall 41 to the upper portion.

The heater wall 41 has a terminal portion 47 through which a current for resistance heating is introduced or output. The terminal portion 47 serves to fix the heater wall 41 to the bottom of the chamber of the single crystal manufacturing apparatus while providing a path through which current is drawn in and output.

The single crystal manufacturing apparatus which concerns on this invention is equipped with the graphite heater mentioned above. The remaining configurations other than the graphite heater may be replaced by any configuration of the single crystal manufacturing apparatus known in the art. As an example, the configuration of the single crystal manufacturing apparatus shown in FIG. 1 may be employed as it is. That is, the single crystal manufacturing apparatus according to the present invention includes a chamber, a quartz crucible, a graphite crucible, a shaft, a crucible driving mechanism, a heat insulating material, a heat shield, a cooling cylinder, a single crystal pulling means, etc. together with the above-described graphite heater.

The single crystal manufacturing apparatus according to the present invention further includes a control unit (not shown) for differently adjusting the relative position of the quartz crucible relative to the graphite heater in the process of melting the single crystal, stabilizing the melt, and growing the single crystal. Hereinafter, the operation of the controller will be described in detail with reference to the accompanying drawings.

6 is a view showing the relative positional relationship between the graphite heater and the quartz crucible in the melting process.

Referring to FIG. 6, when the melting process starts, the controller sets the position of the quartz crucible 50 as a first position condition so that a large amount of heat can be transferred to the bottom of the quartz crucible 50 (below the curved starting point E). do. The position of the quartz crucible 50 is set by driving the shaft 52 supporting the graphite crucible 51. The first position condition is a condition in which the bottom bottom C of the quartz crucible 50 is lower than the center point D of the maximum heat generating part 42. Preferably, when the first location condition is set, the bottom bottom C of the quartz crucible 50 is located 10 to 25 mm below the center point D of the maximum heating part 42. Here, the driving mechanism of the shaft 52 is known, so the description thereof will be omitted.

In the single crystal manufacturing apparatus according to the present invention, the melting process is performed in a state where the first positional conditions are set. Then, the heat emitted from the maximum heat generating portion 42 is concentrated at the bottom of the quartz crucible 50. The maximum heat generating portion 42 dissipates 40% or more of the total amount of heat generated by the graphite heater 40. The maximum heat generating portion 42 preferably has a length of 20% to 30% L when the length of the graphite heater 40 is L. Since the maximum heat generating part 42 generates the maximum heat per unit length, it starts to melt from the polycrystal at the bottom of the quartz crucible 50, and the melting reaction gradually diffuses upward. Therefore, the depression of the polycrystalline raw material is made stable, thereby preventing damage to the quartz crucible 50 and splashing of the melt 53 throughout the melting process.

At the end of the melting process, the quartz crucible 50 is filled with the melt 53. At this time, it is preferable that the local heat generating portion 44 corresponds to the position of the melt surface 54. The local heating unit 43 preferably has a length of 10% to 20% L when the length of the graphite heater 40 is L. The local heating portion 43 concentrates at least 15% of the total calorific value of the graphite heater 40 near the melt surface 54. The viscosity near the melt surface 54 then becomes small. In this case, the external discharge of the fusion by-product gas coming up by convection from the bottom of the quartz crucible 50 is smoothed.

The vicinity of the side wall of the quartz crucible 50 is heated by the stabilizing heating portion 43. The stabilization heating portion 43 preferably has a length of 50% to 70% L when the length of the graphite heater 40 is L. The stabilization heating unit 43 heats the sidewall of the quartz crucible 50 with heat less than 45% of the total amount of heat generated by the graphite heater 40. The amount of heat generated per unit length of the stabilizing heating part 43 is smaller than the maximum heating part 42. Therefore, when the graphite heater 40 is operated at the same power, more heat is not applied to the sidewall of the quartz crucible 50 than before. Therefore, the sidewall of the quartz crucible 50 is suppressed from the thickness variation caused by the softening phenomenon and the peeling of the crystalline precipitate. Therefore, it is possible to prevent the shape deformation of the sidewall of the quartz crucible 50 and to prevent the occurrence of dielectric dislocation in the single crystal.

7 is a view showing the relative positional relationship between the graphite heater and the quartz crucible during the stabilization of the melt after the melting process is completed.

Referring to FIG. 7, when the melting process is completed, the controller sets the relative position of the quartz crucible 50 based on the graphite heater 40 as the second position condition to make the melt 53 supercooled. The supercooled state refers to a melt state for growing single crystals through a solid-liquid interface. The second position condition is a condition in which the bottom bottom C of the quartz crucible 50 is higher than the center point D of the maximum heating part 42. Preferably, the second position condition is a condition in which the bottom bottom C of the quartz crucible 50 is 20 to 30 mm higher than the center point D of the maximum heating part 42. When the second position condition is set, the position of the local heat generating portion 44 is directly below the melt surface 54, preferably the center point F of the local heat generating portion 44 is referred to the height h of the melt 53. To 0.7 to 0.85h. The controller drives the shaft 52 with the setting of the second position condition to gradually rotate the quartz crucible 50. The driving mechanism for setting the second position condition by the control unit is the same as when setting the first position condition.

When the control unit sets the second position condition, the quartz crucible 50 is mainly heated by the stabilizing heating portion 43, and the vicinity of the bottom bottom C of the quartz crucible 50 is heated by the maximum heating portion 42. Directly below the melt surface 54 is heated by the local heat generating section 44.

The stabilization heating unit 43 has a heat generation amount per unit length smaller than the maximum heating unit 42. Thus, the melt 53 enters the supercooled state. Knowing the design conditions of the graphite heater 40, the calorific value and the calorific value distribution of the heater according to the power can be calculated, so that the power of the heater for making the melt 53 supercooled can be easily determined.

The maximum heat generating portion 42 forms a heat shield near the bottom bottom C of the quartz crucible 50. When the heat shield is formed, it is possible to prevent the radiant heat of the melt 53 from being emitted to the bottom of the quartz crucible 50. Therefore, the convection of the melt 53 is stabilized and the reproducibility of the single crystal growth process is improved.

The local heating portion 44 concentrates heating the lower portion of the melt surface 54 to activate the forced convection in the vertical direction and the natural convection in the horizontal direction near the melt surface 54. Here, forced convection is formed by the rotation of the quartz crucible 50 and natural convection is formed by the temperature deviation in the melt 53. When forced convection and natural convection are activated, the temperature gradient of the melt surface 54 increases and the deviation of the temperature gradient in the horizontal direction of the melt surface 54 decreases. In addition, oxygen eluted from the silica constituting the quartz crucible 50 is smoothly supplied to the melt surface 54 side.

The controller starts single crystal growth after a predetermined time has elapsed and when the supercooled state of the melt surface 54 and the convection of the melt 53 are stabilized. That is, the controller controls the single crystal pulling means to immerse the seed crystal on the melt surface 54 and then gradually raises the seed crystal upward while rotating the seed crystal in the opposite direction to the direction of rotation of the quartz crucible 50. Then, the single crystal grows slowly through the solid-liquid interface. As the single crystal growth proceeds, the melt 53 is consumed and the liquid level of the melt is lowered. Accordingly, the controller may drive the shaft 52 to gradually raise the quartz crucible 50 during the single crystal growth to compensate for the lowering of the liquid level. Since single crystal growth is performed by the single crystal growth method by a well-known CZ method, detailed description is abbreviate | omitted.

When the single crystal is grown in the state where the second position condition is set, the forced convection and natural convection near the melt surface 54 are activated by the local heating section 44 as described above. Therefore, it is possible to increase the temperature gradient of the solid-liquid interface and to reduce the temperature gradient variation of the central and peripheral portions of the single crystal. As a result, the defect free pulling speed of the single crystal and the defect free process margin for V / G (V is the pulling speed and G is the temperature gradient of the solid-liquid interface) can be increased. In addition, the oxygen eluted from the quartz crucible 50 may be smoothly supplied to the solid-liquid interface to increase the concentration of oxygen introduced into the single crystal.

The single crystal manufacturing apparatus according to the present invention may further comprise magnetic field applying means 60 to further activate forced convection near the melt surface 54. Preferably, the magnetic field applying means 60 applies a cusp magnetic field to the melt 53. At this time, it is preferable that the ZGP (Zero Gauss Plane) of the cusp magnetic field is located at 0.7 to 0.85 h, which is the center range of the local heating unit 44. More preferably, the ZGP is located in the center of the localized heat generating portion 44. If the ZGP position of the cusp magnetic field satisfies the above conditions, the convection is stabilized as a whole of the melt 53, but the magnetic field is weakened near the melt surface 54 to further activate forced convection near the melt surface 54. Then, the above-described effects generated by the local heating unit 44 during single crystal growth are further enhanced. On the other hand, since the technique for applying the cusp magnetic field is known in the art of single crystal growth using the CZ method, a detailed description of the magnetic field applying means is omitted.

Next, a single crystal manufacturing method according to an embodiment of the present invention will be described with reference to the process flowchart shown in FIG. 8.

First, in step S10, a graphite heater is installed around the quartz crucible. Here, the graphite heater includes a maximum heating part, a stabilizing heating part and a local heating part. The structure of the graphite heater is well disclosed in FIGS. 4 and 5.

Subsequently, in step S20, the relative position of the quartz crucible and the graphite heater is set as the first position condition. The first position condition is a condition in which the bottom bottom of the quartz crucible is lower than the center of the maximum heating portion.

Next, in step S30, the graphite heater is operated to melt the polycrystalline raw material introduced into the quartz crucible. In this step, since the melting of the polycrystal is mainly performed at the bottom of the quartz crucible, it is possible to stably melt the polycrystal. In addition, since the melt surface becomes less viscous by the local heating unit, smooth external discharge of gas generated by melting of the polycrystal is possible. In addition, since the quartz crucible sidewall is heated by the stabilizing heating portion, it is possible to suppress the crystalline precipitates from being deformed by the softening of the quartz crucible sidewall and the shape deformation of the quartz crucible.

Subsequently, in step S40, the relative position of the quartz crucible and the graphite heater is set as the second position condition. The second position condition is a condition in which the bottom bottom of the quartz crucible is higher than the center of the maximum heating portion. When this condition is set, the maximum heating part of the graphite heater provides a heat shield near the bottom of the quartz crucible, the local heating part activates forced convection and natural convection near the melt surface, and the stabilizing heating part makes the melt supercooled. . In the second position condition, the center of the local heating portion is preferably located at 0.7 to 0.85 h based on the height h of the melt.

Then, in step S50, the quartz crucible is slowly rotated to stabilize the supercooled state of the melt surface and the convection of the melt.

Next, in step S60, after the seed crystals are immersed in the melt, the single crystals of the target diameter are grown to a desired length through the solid-liquid interface while rotating the seed crystals in a direction opposite to the rotation direction of the quartz crucible.

Preferably, the liquid level decrease of the melt due to the melt consumption during the single crystal growth process is compensated for. Liquid level compensation is performed by adjusting the position of the quartz crucible. Optionally, a cusp magnetic field is applied to the melt. In this case, the ZGP of the cusp magnetic field places the ZGP near the melt surface, preferably at 0.7-0.85 h (h is the melt depth). More preferably, the ZGP of the cusp magnetic field coincides with the center position of the local heating portion. In addition, when the cusp magnetic field is applied, as the single crystal grows, the position of the magnetic field applying means may be adjusted to compensate for the positional change of the ZGP due to the liquid level decrease of the melt.

Experimental Example

Hereinafter, the present invention will be described in more detail through experimental examples. The following experimental examples are described for the purpose of helping the understanding of the present invention, and the present invention should not be construed to limit the present invention to terms or experimental conditions described in the experimental examples.

Comparative example

Silicon single crystals used for 300 mm wafers were grown using the conventional heaters shown in FIGS. 2 and 3. In the melting and stabilization process of the single crystal, the center point of the heater was positioned at 0.6 h based on the melt height h (the height when all the single crystals were melted). During the single crystal pulling up after the stabilization process, the process conditions including the single crystal pulling rate were controlled within a flawless margin so that the single crystal did not cause crystal defects resulting from bacon or lattice silicon.

Example

Silicon single crystals used for 300 mm wafers were grown using a heater according to the invention shown in FIGS. 4 and 5. In the melting process of the single crystal, the bottom of the quartz crucible was 15 mm lower than the center point of the maximum heating part. In the melt stabilization step, the bottom of the quartz crucible was 22 mm higher than the center point of the maximum heating part. During the single crystal pulling up after the stabilization process, the process conditions including the single crystal pulling rate were controlled within a flawless margin so that the single crystal did not cause crystal defects resulting from bacon or lattice silicon.

Comparison of the time taken to stabilize

FIG. 9 is a graph illustrating a comparison between the time taken for the melting and stabilization of the polycrystal to be completed and the power fluctuation of the heater in Comparative Examples and Examples. Referring to the drawings, the melting process and the stabilization process could be completed more quickly by the heater power, which is relatively low in the case of the example compared to the comparative example. From this, it can be seen that when the single crystal is manufactured using the graphite heater according to the present invention as a heat source, productivity can be increased and power required for the heater operation in the polycrystalline melting and stabilization process can be reduced.

Comparison of Oxygen Concentrations of Single Crystals

10 is a graph showing the results of measuring the oxygen concentration of the single crystal grown by the comparative example and the example along the length of the single crystal body section. Referring to the drawings, the oxygen concentration of the single crystal was higher in the case of the example than in the comparative example. From this, it can be seen that the growth of the single crystal using the graphite heater according to the present invention as a heat source can increase the strength of the wafer and the concentration of BMD serving as a collecting site of impurities.

Comparison of the temperature distribution of the melt

FIG. 11 is a graph illustrating measurement of horizontal and vertical temperature distributions of a melt immediately after the stabilization process of the melt is completed in Comparative Examples and Examples. Referring to the drawings, the temperature change was higher in the vertical direction of the melt surface in the case of the Example than in the comparative example, while the temperature change was small in the horizontal direction of the melt. From this, growing the single crystal using the graphite heater according to the present invention can increase the vertical temperature gradient of the melt surface to increase the single crystal pulling rate within the defect free margin. In addition, the temperature deviation in the horizontal direction of the melt decreases, thereby increasing the process margin of V / G (G is the temperature gradient of the solid-liquid interface, V is the pulling rate) to grow a defect-free single crystal.

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.

The following drawings, which are attached to this specification, illustrate exemplary embodiments of the present invention, and together with the detailed description of the present invention serve to further understand the technical spirit of the present invention, the present invention includes matters described in such drawings. It should not be construed as limited to.

1 is a cross-sectional view schematically showing the configuration of a conventional single crystal production apparatus using the CZ method.

2 is a front view of a conventional graphite heater.

3 is a rear view of a conventional graphite heater.

4 is a front view of the graphite heater according to the embodiment of the present invention.

5 is a rear view of the graphite heater according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating a relative positional relationship between a quartz crucible and a graphite heater in a polycrystalline melting process.

7 is a diagram showing the relative positional relationship between the quartz crucible and the graphite heater in the stabilization process of the melt.

8 is a process chart showing the procedure of the single crystal manufacturing method according to an embodiment of the present invention.

FIG. 9 is a graph illustrating a comparison between a power change of a heater according to time and a time required when a single crystal melting process and a melt stabilization process are performed according to a comparative example and an embodiment.

10 is a graph illustrating comparison of oxygen concentrations by length of single crystals when single crystals are grown according to Comparative Examples and Examples.

11 is a graph illustrating a comparison of the temperature distribution of melts measured in the horizontal direction and the vertical direction of the surface of the melt after completion of the melting process and the melt stabilization process of the polycrystals according to Comparative Examples and Examples.

Claims (18)

delete delete delete delete A quartz crucible in which a melt of a polycrystalline raw material is accommodated; A graphite crucible supporting the shape of the quartz crucible; Installed around the graphite crucible, the quartz crucible is heated above the melting temperature of the polycrystalline raw material, and is provided with a maximum heating part, a stabilizing heating part, and a local heating part formed by stepping on the outer wall of the heater wall while going from bottom to top. Graphite heaters; Crucible driving means for rotating and raising / lowering the graphite crucible; And In the single crystal manufacturing apparatus comprising a single crystal pulling means for immersing the seed crystals attached to the wire in the melt contained in the quartz crucible and then pulling the single crystals upward through the solid-liquid interface, The length of the maximum heating part, the stabilizing heating part and the local heating part of the graphite heater corresponds to the height of the melt surface of the local heating part in the first positional condition where the bottom bottom of the quartz crucible is lower than the center of the maximum heating part. A single crystal manufacturing apparatus, characterized in that the center of the local heating portion is located at 0.7 ~ 0.85h on the basis of the height h of the melt under the second position condition that the bottom bottom is higher than the center of the maximum heating portion. The method of claim 5, Single crystal manufacturing apparatus, characterized in that the maximum heating portion has a length of 20% to 30% L, the local heating portion has a length of 10% to 20% L based on the length L of the graphite heater. The method of claim 5, wherein the graphite heater,  And wherein the maximum heat generating portion provides 40% or more of the total calorific value and the local heat generating portion provides 15% or more of the total calorific value. The method of claim 5, The bottom bottom of the quartz crucible in the first position condition is 10 to 25 mm lower than the center of the maximum heating portion, and the bottom bottom of the quartz crucible in the second position condition is 20 to 30 mm higher than the center of the maximum heating portion. Manufacturing device. The method of claim 5, The stabilizing heating unit includes a first stabilizing heating unit and a second stabilizing heating unit having different steps, And the first stabilized heat generating portion is in contact with the maximum heat generating portion, and generates a larger amount of heat than the second stabilized heat generating portion. The method of claim 5, The heater wall has a zigzag-type current flow path by partially cutting the upper slit cut from the upper end and the lower slit spaced apart from the upper slit and cut from the lower end to the upper end in a repeating unit. Single crystal manufacturing apparatus. The method of claim 5, And a magnetic field applying means for applying a cusp magnetic field such that ZGP is located at 0.7 to 0.85 h based on the height h of the melt. (a) loading a polycrystalline raw material into a quartz crucible; (b) providing a graphite heater provided around the quartz crucible having a maximum heating portion, a stabilizing heating portion, and a local heating portion formed by stepping on an outer wall of the heater wall while going from bottom to top; (c) adjusting the height of the quartz crucible under a first positional condition in which a bottom bottom of the quartz crucible is lower than the center of the maximum heating part and a local heating part corresponds to the melt surface; (d) operating the graphite heater to melt polycrystalline raw materials in a quartz crucible; (e) adjusting the height of the quartz crucible under a second position condition in which the bottom bottom of the quartz crucible is higher than the center of the maximum heating part and the center of the local heating part is located at 0.7 to 0.85 h based on the height h of the melt; ; And (f) stabilizing the melt and immersing seed crystals in the melt, followed by pulling up a single crystal through a solid-liquid interface. The method of claim 12, The step (c) is characterized in that the bottom of the quartz crucible is 10 to 25 mm lower than the center of the maximum heating portion. The method of claim 12, The step (e) is characterized in that the bottom of the quartz crucible 20 to 30 mm higher than the center of the maximum heat generating portion single crystal manufacturing method. The method of claim 12, The step (d) is a single crystal manufacturing method characterized in that for operating the graphite heater such that the maximum heat generating portion provides more than 40% of the total heat generation amount, the local heat generating portion provides more than 15% of the total heat generation amount. delete The method of claim 12, Single crystal manufacturing method characterized in that in step (e) applying a cusp magnetic field in which ZGP is located at 0.7 ~ 0.85h based on the melt height h to the melt. The method of claim 17, Single crystal manufacturing method characterized in that in the step (f) to compensate for the lowering of the liquid level and the position elevation of the ZGP due to the growth of the single crystal.

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