JP5289294B2 - Quartz crucible for pulling silicon single crystal - Google Patents

Description

  The present invention is a crucible used in manufacturing a silicon single crystal, and is used in particular in the Czochralski method, so that the silicon single crystal is pulled into the quartz crucible for a long period of time. The present invention relates to a single crystal pulling crucible to which is continuously supplied and a single crystal pulling method using the crucible.

  Conventionally, the Czochralski method (hereinafter referred to as “CZ method”) is used for the production of a silicon single crystal because of the advantages that a large crystal can be grown and the speed of crystal growth is high. In recent years, for the purpose of producing a large amount of silicon single crystal, the silicon raw material melt is continuously supplied from the outside to the silicon single crystal pulling crucible, so that the liquid surface height position of the silicon raw material melt is substantially reduced. A silicon single crystal pulling method has been developed that enables the silicon single crystal to be pulled in a constant state.

  As a method for pulling up the silicon single crystal continuous for a long time, as shown in FIG. 1, the solid silicon raw material 2 is melted with a melt supply crucible 3, and the molten silicon raw material melt 5 is melted into a melt supply pipe 4. Then, the silicon single crystal pulling crucible 20 is supplied to the silicon single crystal pulling crucible 10 and the silicon single crystal is pulled up with the liquid surface height position H0 of the silicon raw material melt 5 substantially constant. For example, pulling up a silicon single crystal using a crystal raw material melting apparatus as disclosed in Patent Document 1.

  However, when the silicon single crystal is pulled by these pulling methods, it is effective in that many silicon single crystals can be pulled continuously. However, the silicon melt liquid supplied into the quartz crucible is effective. Since the surface does not vary at a substantially constant height position, there is a problem that the inner wall portion corresponding to the height position of the silicon melt surface of the quartz crucible is eroded (melted).

  The pulling of the silicon single crystal is performed in a high temperature environment of about 1500 ° C., and the quartz crucible is softened at a temperature of about 1150 ° C. Therefore, when the pulling continues for a long time (for example, 200 hours or more), This melting loss causes the quartz crucible to fall down or buckle, leading to a shortened use period of the quartz crucible. Therefore, even when the silicon raw material melt is supplied continuously or intermittently and the liquid level height position of the silicon raw material melt is substantially constant in the silicon crucible, the melting of the quartz crucible is performed. Development of a technique capable of suppressing breakage of a quartz crucible due to damage is desired.

  Here, Patent Document 2 discloses a crucible characterized in that the inner surface of the straight portion of the graphite crucible is inclined so that the diameter gradually increases from the lower portion toward the upper portion in order to suppress inward tilting and buckling. Has been. However, inward tilting and buckling caused by erosion (melting damage) of the inner wall portion corresponding to the height position of the silicon melt surface of the quartz crucible cannot be sufficiently solved.

Japanese Patent Laid-Open No. 10-25190 JP 2007-76974 A

  An object of the present invention is to optimize the shape of the quartz crucible so that the silicon raw material melt is continuously or intermittently supplied to the quartz crucible, and the liquid surface height position of the silicon raw material melt is within the quartz crucible. An object of the present invention is to provide a single crystal pulling crucible and a single crystal pulling method capable of suppressing breakage of a quartz crucible due to erosion of an inner wall even in a substantially constant state.

  The present inventors have a double structure of a quartz crucible containing a silicon raw material melt and a graphite crucible covering the outside of the quartz crucible, and the liquid surface height position of the silicon raw material melt is substantially within the quartz crucible. The silicon single crystal pulling crucible in which the silicon raw material melt is continuously or intermittently supplied into the quartz crucible so as to be in a constant state as a result of repeated investigations to solve the above problems. By providing a side wall reinforcing portion made of a quartz material on the outer periphery of the side wall corresponding to the liquid surface height position of the raw material melt to make the side wall portion a thick side wall portion, the thick side wall portion becomes a silicon single crystal. At the time of pulling up, the quartz crucible is heated and softened, and deforms corresponding to the shape of the inner wall surface of the graphite crucible, and the thick side wall portion of the quartz crucible partially protrudes toward the inner surface side. Liquid level high Even if the inner wall portion corresponding to the position range is eroded was found to be able to effectively suppress the breakage of the quartz crucible caused by it.

In order to achieve the above object, the gist of the present invention is as follows.
(1) It has a double structure of a quartz crucible containing a silicon raw material melt and a graphite crucible covering the outside of the quartz crucible, and the liquid surface height position of the silicon raw material melt is substantially constant in the quartz crucible. A silicon single crystal pulling crucible in which a silicon raw material melt is continuously supplied into the quartz crucible so that the silicon single crystal is pulled in the state of A side wall reinforcing portion made of a quartz material is provided at a height position of the quartz material, the side wall portion is a thick wall side wall portion, the quartz crucible is heated and softened when the silicon single crystal is pulled, and the thick wall side wall portion is the graphite crucible. A silicon single crystal pulling crucible, characterized in that the thick side wall portion of the quartz crucible partially protrudes toward the inner surface side by being deformed corresponding to the inner wall surface shape.

(2) The silicon single crystal pulling crucible according to the above (1), wherein the thick side wall portion has a thickness of 110 to 150% with respect to a thickness of the side wall excluding the side wall reinforcing portion of the quartz crucible.

(3) The thick side wall portion is provided such that the height position of the upper end portion thereof is measured in the range of 50 to 90% of the distance to the upper end of the side wall as measured from the lower end of the side wall of the quartz crucible. The silicon single crystal according to the above (1) or (2), wherein the height position of the lower end portion is located in the range of 40 to 80% of the distance to the upper end of the side wall as measured from the lower end of the side wall of the quartz crucible A crucible for lifting.

(4) The quartz crucible for pulling up a silicon single crystal according to any one of the above (1) to (3), wherein the outer diameter of the upper end of the trunk is 0.1% or more larger than the outer diameter of the lower end of the trunk.

(5) The quartz crucible is a crucible for pulling up a silicon single crystal according to any one of (1) to (4) above, wherein the outer diameter of the upper end of the body portion is in the range of 700 to 1120 mm.

(6) Pulling a silicon single crystal ingot having a diameter of 300 mm or more using the silicon single crystal pulling crucible described in any one of (1) to (5) above, pulling a silicon single crystal Method.

  According to the present invention, the silicon raw material melt is continuously or intermittently supplied to the quartz crucible, and the liquid surface height position of the silicon raw material melt is substantially constant in the silicon crucible. However, it has become possible to provide a crucible for pulling a single crystal and a method for pulling a single crystal that can suppress the damage of the quartz crucible due to the erosion of the inner wall.

It is sectional drawing which showed the single crystal pulling apparatus typically. It is the sectional side view which showed typically the quartz crucible of this invention. FIG. 2 is a side sectional view schematically showing a single crystal pulling crucible of the present invention, in which (a) shows a state immediately after the silicon melt is formed, and (b) shows the supply of the silicon raw material melt to the crucible of (a). This shows the state when the pulling is continued for a long time while continuously or intermittently.

Hereinafter, the configuration of the present invention and the reasons for limitation will be described with reference to FIGS.
FIG. 1 is a side sectional view schematically showing a single crystal pulling apparatus of the present invention, and FIG. 2 is a side sectional view schematically showing an embodiment of a quartz crucible of the present invention. FIG. 2 is a side sectional view schematically showing a single crystal pulling crucible of the present invention, in which (a) shows a state immediately after a silicon melt is formed, and (b) shows a silicon raw material melt in a crucible of (a). It shows the state when the pulling is continued for a long time while the supply of is continuously or intermittently performed.

As shown in FIG. 1, the single crystal pulling crucible according to the present invention has a double structure of a quartz crucible 20 containing a silicon raw material melt 5 and a graphite crucible 30 covering the outside of the quartz crucible 20, and the quartz crucible The silicon raw material melt 5 is continuously introduced into the quartz crucible 20 so that the silicon single crystal 6 is pulled up with the liquid surface height position H0 of the silicon raw material melt 5 being substantially constant in the inside 20. The silicon crucible pulling crucible 20 is supplied either intermittently or intermittently, and the quartz crucible 20 has a side wall made of a quartz material at a predetermined height position H on the outer periphery of the side wall 21, as shown in FIG. As shown in FIGS. 3 (a) and 3 (b), the quartz crucible 20 is heated and softened when the silicon single crystal 5 is pulled up, as shown in FIGS. 3 (a) and 3 (b). 23 parts of thick side wall Due to the deformation corresponding to the shape of the inner wall surface 30a of the graphite crucible 30, the thick side wall portion 23 of the quartz crucible 20 partially protrudes toward the inner surface side (FIG. 3B). .
By adopting the above configuration, even when the inner wall portion 21 corresponding to the height position range (H1 to H3) of the surface of the silicon melt 5a is eroded, the thick wall provided with the side wall reinforcing portion 22 is provided. Since the side wall portion 23 becomes thicker toward the inner surface of the crucible, breakage of the quartz crucible 20 due to erosion (buckling, inward tilt, etc.) can be effectively suppressed.

  In the prior art, the side wall reinforcing portion 22 is provided in advance on the inner wall of the quartz crucible 20 so that the thick side wall portion 23 of the quartz crucible 20 partially protrudes toward the inner surface side. It is difficult to manufacture. The quartz crucible is manufactured by a so-called arc melting method in which quartz raw material powder is brought into close contact with a rotating crucible-shaped mold using a centrifugal force, and an arc is generated therein to melt the quartz powder. The raw material quartz powder is melted from the inner surface toward the outer surface, and its temperature is higher on the inner surface side than on the outer side, and conversely, the viscosity of the fused quartz glass is lower on the inner surface side. As a result, when the side wall reinforcing portion 22 is provided on the inner surface side of the quartz crucible 20, the inner surface of the quartz crucible that is being pulled up gradually falls downward due to gravity, and therefore when the quartz raw material powder is brought into close contact with the mold, the side wall Even if the reinforcing portion 22 is formed in a convex shape, it is difficult to realize a shape in which the portion formed in the convex shape is flattened and flows downward and partially protrudes toward the inner surface. Therefore, in the present invention, the side wall reinforcing portion 22 is once provided on the outside, and the thick side wall portion 23 is partially formed on the inner surface side of the quartz crucible 20 by utilizing the subsequent softening of the quartz crucible 20 by heat. It is possible to make a shape that protrudes.

  The side wall reinforcing portion 22 constituting the thick-walled side wall portion 23 is not particularly limited as long as it is made of a quartz material. From the viewpoint of adhesiveness to the quartz crucible 20, the material of the quartz crucible 20 and It is preferable to consist of the same material.

  As shown in FIG. 2, the side wall reinforcing portion 22 needs to be provided at a predetermined height position H corresponding to the liquid surface height position of the silicon raw material melt 5. The quartz glass constituting the quartz crucible 20 reacts with the molten silicon and dissolves in the silicon raw material melt 5 and then circulates in the melt 5 and then partially evaporates as a gas. However, in the vicinity of the surface of the melt, since it is in contact with the atmospheric gas, most of the dissolved quartz glass immediately evaporates after the quartz glass is dissolved. As a result of the vigorous dissolution reaction in the silicon melt, the amount of erosion of the inner wall portion of the silicon raw material melt 5 in contact with the liquid surface 5a increases, leading to the quartz crucible 20 falling down or buckling. is there. Note that the liquid surface height position H0 of the raw silicon melt 5 is substantially constant is not strictly constant height position. In the present invention, any liquid surface height position of the melt 5 is used. The range of ± 20mm with H0 as the center.

  Further, as shown in FIG. 2, the thick side wall portion 23 provided with the side wall reinforcing portion 22 effectively suppresses erosion of the inner wall of the quartz crucible 20, and further eliminates the unnecessary side wall reinforcing portion 22. From the point of prevention, it is limited to a certain height range. Specifically, the height position H1 of the upper end 23a is measured from the lower end U of the side wall of the quartz crucible 20, and It is provided in the range of 50 to 90% of the distance X to the upper end T, and the height position H3 of the lower end 23b is measured from the lower end U of the side wall of the quartz crucible 20, and is the distance to the upper end T of the side wall. It is preferably located in the range of 40 to 80% of X. When the height position H1 of the upper end portion 23a is less than 50% of the distance X and when the height position H2 of the lower end portion 23b exceeds 80% of the distance X, the actual liquid of the silicon raw material melt 5 Since the surface height position cannot be accommodated, the quartz crucible may not be prevented from being damaged at a portion outside the range. On the other hand, the height position H1 of the upper end 23a exceeds 90% of the distance X. When the height position H2 of the lower end portion 23b is less than 40% of the distance X, the side wall reinforcing portion 22 is provided beyond the actual liquid level height position range of the silicon raw material melt 5. This is because it is not preferable in terms of cost.

  As shown in FIG. 2, the thick side wall portion 23 has a thickness A1 of 110 to 150% with respect to the thickness A2 of the side wall excluding the side wall reinforcing portion 22 of the quartz crucible 30. preferable. When the thickness A1 of the thick side wall portion 23 is less than 110% with respect to the thickness A2 of the side wall excluding the side wall reinforcing portion 22, the thick side wall portion 23 is too thin. This is because damage to the quartz crucible 20 due to erosion of the corresponding inner wall portion 21 cannot be sufficiently suppressed. On the other hand, when the thickness A1 exceeds 150% with respect to the thickness A2, the thick side wall portion 23 becomes thick. This is because the weight of the thick side wall portion 23 may cause buckling or inward collapse of the quartz crucible 20. In FIGS. 2 and 3, the side wall reinforcing portion 22 and the thick side wall portion 23 are shown in an exaggerated state in order to easily explain the thick side wall portion 23.

  Further, the quartz crucible 20 is preferably formed such that the outer diameter W of the body portion gradually increases from the lower part toward the upper part as shown in FIG. 2, and specifically, the outer diameter W1 of the upper end 20a of the body part is More preferably, it is 0.1% or more larger than the outer diameter W2 of the trunk lower end 20c. This is because the effect of suppressing inward tilting and buckling of the side wall 21 of the quartz crucible 20 is improved. If the outer diameter W1 of the barrel upper end 20a is not more than 0.1% larger than the outer diameter W2 of the barrel lower end 20c, quartz This is because the side wall 21 of the crucible 20 may not be able to sufficiently exhibit the effect of suppressing the internal falling and buckling. On the other hand, if the difference between the outer diameter W1 of the barrel upper end 20a and the outer diameter W2 of the barrel lower end 20c becomes too large (for example, more than 10 mm), the position immediately above and directly below the liquid surface 5a of the silicon raw material melt 5 Since the difference in the inner diameter of the crucible 20 increases, the position may become the starting point of buckling.

  Furthermore, it is preferable that the quartz crucible has an outer diameter at the upper end of the body portion in a range of 700 to 1120 mm. The silicon single crystal pulling crucible 10 of the present invention is intended for large-diameter wafers and is used at a higher temperature than a small-diameter crucible having the above range of 700 mm or less. In addition, the quartz crucible can be prevented from being damaged due to the erosion of the inner wall.

  Note that the structure of the graphite crucible 30 constituting the silicon single crystal pulling crucible 10 of the present invention is not particularly limited, and a commonly used graphite crucible may be used.

  The size of the silicon single crystal pulling crucible of the present invention is not particularly limited because crucibles of various sizes are required depending on the size of the silicon single crystal ingot to be pulled.

  Further, the method for supplying the silicon raw material melt 5 continuously or intermittently into the quartz crucible 20 is not particularly limited, and any supply method may be used. For example, as shown in FIG. 1, a melt supply crucible 3 for melting a solid silicon raw material 2 disposed outside a single crystal pulling crucible 10, and silicon melted by the melt supply crucible 3 By using the melt supply pipe 4 for conveying the raw material melt 5, the silicon raw material melt 5 can be supplied into the silicon crucible 20.

  A method for manufacturing the quartz crucible is not particularly limited as long as the side wall reinforcing portion 22 having a special shape can be manufactured with high accuracy, but it is preferable to manufacture the quartz crucible by an arc method. Manufacturing by arc melting is advantageous in terms of cost because it can be manufactured in a short time with a wide range of high-temperature flames, and in addition, it can be manufactured according to the shape of the crucible type. On the other hand, when manufacturing with other manufacturing methods, for example, an oxyhydrogen burner, since the thick reinforcing portion 22 is welded to the conventional quartz crucible 20, the flame range may be small, and the working time This is because the length and the productivity and cost are increased, and more hydroxyl groups in the flame are incorporated into the glass, which may cause a decrease in viscosity. In addition, since the oxyhydrogen burner is locally heated, strain remains in the weld, and the crucible is damaged if the entire crucible after welding is not annealed at a temperature higher than the strain point.

  Next, the silicon single crystal pulling method of the present invention will be described. The silicon single crystal pulling method according to the present invention is characterized by pulling up a large-diameter silicon single crystal ingot having a diameter of 300 mm or more using the above-described single crystal pulling crucible 10 according to the present invention. This is because if this silicon single crystal pulling method is used, it is possible to pull the single crystal silicon ingot over a long period of time while effectively suppressing breakage of the quartz crucible due to erosion of the inner wall.

  Furthermore, the pulling of the single crystal is preferably performed by continuously pulling up one single crystal ingot for a long time. The quartz crucible 20 of the present invention corresponds to a substantially constant liquid level height range of the silicon raw material melt. When the single crystal ingot is continuously pulled up for a long time, the quartz crucible 20 of the present invention is more effectively used. It is because an effect can be produced.

  The above description is merely an example of the embodiment of the present invention, and various modifications can be made within the scope of the claims.

(Examples 1-3)
In Examples 1 to 3, a silicon single crystal pulling-up having a double structure of a quartz crucible 20 having an outer diameter of 810 mm and a height of 500 mm and a graphite crucible 30 covering the outside and having an inner diameter of 815 mm and a depth of 480 mm. The crucibles 10 for use were produced as samples.
As shown in FIG. 2, the quartz crucible 20 has a side wall reinforcement made of the same material as the quartz crucible on the outer periphery of the side wall 21 corresponding to the liquid surface height position (300 to 450 mm) of the silicon raw material melt 5. The portion 22 is provided to form the thick side wall portion 23, and the quartz crucible 20 is heated and softened when the silicon single crystal 5 is pulled, as shown in FIGS. 3 (a) and 3 (b). The thick side wall portion 23 is deformed corresponding to the shape of the inner wall surface 30a of the graphite crucible 30 so that the thick side wall portion 23 of the quartz crucible 20 partially protrudes toward the inner surface side. , The thickness A1 of the thick side wall portion 23 (expressed as a ratio (%) with respect to the thickness A2 of the side wall 21 excluding the side wall reinforcing portion 22), and the height positions H1 and H3 of the upper end 23a and the lower end 23b (quartz Measured from the lower end U of the side wall 21 of the crucible 20, For the display) the percentage (%) at the distance X to the edge T, shown in Table 1. Further, the outer diameter W1 of the trunk upper end 20a is 6 mm larger than the outer diameter W2 of the trunk lower end 20c.
Further, as shown in FIG. 1, the silicon raw material melt in the quartz crucible 20 is obtained by melting the solid silicon raw material 2 with the melt supply crucible 3 and passing the molten silicon raw material melt 5 through the melt supply pipe 4. The quartz crucible 20 was supplied.

Comparative example

(Comparative example)
In the comparative example, silicon was formed under the same conditions as in Example 1 except that the side wall reinforcing portion 22 was not provided on the outer periphery of the side wall 21 of the quartz crucible 20 and the thick side wall portion 23 was not formed on the side wall portion. A crucible for pulling a single crystal was produced.
Further, as shown in FIG. 1, the silicon raw material melt in the quartz crucible 20 is obtained by melting the solid silicon raw material 2 with the melt supply crucible 3 and passing the molten silicon raw material melt 5 through the melt supply pipe 4. The quartz crucible 20 was supplied.

(Evaluation method)
Using each of the crucibles of the example and the comparative example in a single crystal pulling apparatus as shown in FIG. 1, pulling up four silicon single crystal ingots under a pulling condition of a silicon melt temperature of 1500 ° C. (230 hours continuous) Went. Thereafter, the quartz crucible was collected, and evaluation was performed by confirming the presence or absence of inward collapse and buckling due to erosion of the inner wall of the quartz crucible.

  From the results of Table 1, the silicon single crystal pulling crucibles of Examples 1 to 3 did not generate any buckling or inward tilting of the quartz crucible, and were able to effectively suppress the damage of the quartz crucible. I understand. On the other hand, in the crucible for pulling up the silicon single crystal of the comparative example, the quartz crucible was tilted and buckled due to the erosion of the inner wall of the quartz crucible.

  According to the present invention, the silicon raw material melt is continuously or intermittently supplied to the quartz crucible, and the liquid surface height position of the silicon raw material melt is substantially constant in the silicon crucible. However, it has become possible to provide a crucible for pulling a single crystal and a method for pulling a single crystal that can suppress the damage of the quartz crucible due to the erosion of the inner wall.

DESCRIPTION OF SYMBOLS 1 Single crystal pulling apparatus 2 Solid silicon raw material 3 Melt supply crucible 4 Melt supply pipe 5 Silicon raw material melt 6 Silicon single crystal ingot 10 Silicon single crystal pulling crucible 20 Quartz crucible 21 Side wall 22 Side wall reinforcement 23 Thick side wall 30 Graphite crucible

Claims (6)

A quartz crucible containing a silicon raw material melt,
It has a body consisting of a cylindrical side wall,
The trunk includes a thick side wall provided at a predetermined height position of the side wall,
The thick side wall portion has a side wall reinforcing portion provided so as to protrude outward from the outer periphery of the side wall,
The thick side wall portion is heated and softened when the silicon single crystal is pulled, and is formed so as to protrude toward the inner surface side when deformed corresponding to the inner wall surface shape of the graphite crucible covering the outer side of the quartz crucible. A quartz crucible for pulling a silicon single crystal. The quartz crucible for pulling a silicon single crystal according to claim 1, wherein the thick side wall portion has a thickness of 110 to 150% with respect to the thickness of the side wall excluding the side wall reinforcing portion. The thick side wall portion is provided such that the height position of its upper end portion is in the range of 50 to 90% of the distance to the upper end of the side wall as measured from the lower end of the side wall, and the height position of the lower end portion thereof. The quartz crucible for pulling a silicon single crystal according to claim 1 or 2 , wherein the quartz crucible is located in a range of 40 to 80% of a distance to the upper end of the side wall as measured from the lower end of the side wall. The quartz crucible for pulling a silicon single crystal according to any one of claims 1 to 3 , wherein an outer diameter of an upper end of the body portion is 0.1% or more larger than an outer diameter of a lower end of the body portion. The quartz crucible for pulling up a silicon single crystal according to any one of claims 1 to 4 , wherein an outer diameter of an upper end of the body portion is in a range of 700 to 1120 mm. A quartz crucible containing a silicon raw material melt,
It has a body consisting of a cylindrical side wall,
The trunk includes a thick side wall provided at a predetermined height position of the side wall,
The thick side wall portion has a side wall reinforcing portion provided so as to protrude outward from the outer periphery of the side wall,
The thick side wall portion is provided such that the height position of its upper end portion is in the range of 50 to 90% of the distance to the upper end of the side wall as measured from the lower end of the side wall, and the height position of the lower end portion thereof. However, the quartz crucible for pulling a silicon single crystal is located in the range of 40 to 80% of the distance to the upper end of the side wall as measured from the lower end of the side wall.

Images