JP2006169016A - Method for producing silicon single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve production efficiency of a silicon electrode plate by preventing the occurrence of crystal cracks in the cutting process. <P>SOLUTION: The method for producing a silicon single crystal comprises a step for pulling up a silicon single crystal rod 25 having a given length while surrounding it with a cylindrical heat-shielding member 36 from a silicon melt 12 that is obtained by heat-melting a silicon raw material stored in a quartz crucible 13 installed in a CZ furnace 11 by means of an electric heater 18, a step for separating the silicon single crystal rod from the silicon melt by temporally lowering the crucible, and a step for heat-treating the lower part of the silicon single crystal rod for a given period of time by exposing the lower part from the bottom end of the heat-shielding member by lowering the separated silicon single crystal rod and the crucible together to a given position and by directly exposing the exposed lower part to the heat of the heater. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a silicon single crystal suitable for producing a silicon electrode plate which is a main part of a plasma etching apparatus used in a semiconductor production process.

  One of the processes for manufacturing a semiconductor device is a process for etching a silicon wafer, and a plasma etching apparatus is used as an apparatus for etching the silicon wafer. As shown in FIG. 6, a general plasma etching apparatus includes a vacuum container 1 capable of maintaining the inside thereof in a vacuum, and a gas supply port 1 a capable of supplying an etching gas from the outside is provided at the top of the vacuum container 1. Gas outlets 1b that can discharge gas to the outside are provided at the bottom. A disc-shaped electrode plate 2 is provided horizontally inside the vacuum vessel 1, and the etching gas supplied from the etching gas supply port 1 a is installed so as to pass through the electrode plate 2. The electrode plate 2 is provided with a plurality of through holes 5 in a direction perpendicular to the disk-shaped plane, and the etching gas supplied from the etching gas supply port 1 a is uniformly blown out from the plurality of through holes 5. A support plate 3 is provided inside the vacuum vessel 1 at a certain distance from the electrode plate 2, and a silicon wafer 4 to be etched is placed on the support plate 3. A high frequency power source 6 for applying a high frequency voltage between the electrode plate 2 and the silicon wafer 4 is connected to the gas supply port 1 a and the support plate 3. In the plasma etching apparatus configured as described above, after the silicon wafer 4 is placed on the support plate 3, the etching gas 7 is supplied from the gas supply port 1 a and the silicon is passed through the through-holes 5 provided in the electrode plate 2. A high frequency voltage is applied between the electrode plate 2 and the support plate 3 by the high frequency power source 6 while flowing toward the wafer 4. Plasma 8 is generated in the space between the electrode plate 2 and the silicon wafer 4 by the application of the high frequency voltage. The surface of the silicon wafer 4 is etched by sputtering or physical reaction by the plasma 8 and chemical reaction by the silicon-etching gas.

Conventionally, a silicon electrode plate made of disc-shaped single crystal silicon has been mainly used as an electrode plate of a plasma etching apparatus. For example, there is disclosed a silicon electrode plate for plasma etching with less particle generation, which is made of single crystal silicon having a COP density of 10 ⁴ pieces / cm ³ or less (see, for example, Patent Document 1). When a silicon wafer is plasma-etched using the silicon electrode plate disclosed in Patent Document 1, the generation of defective products due to the generation of particles can be greatly reduced, which can greatly contribute to the development of the semiconductor device industry.
JP 2001-338913 A (Claim 1, paragraph [0024])

  On the other hand, in order to manufacture this silicon electrode plate, a large-diameter silicon single crystal rod of about φ240 mm to φ450 mm was used as a base material. In the growth of a silicon single crystal rod serving as a base material, first, a furnace of a silicon single crystal growing apparatus is heated with a heater, and a seed crystal is immersed in a silicon melt melted in the heated furnace. Next, while pulling up the seed crystal, the seed squeezed part, the cone part, the shoulder part and the straight body part are grown by a normal Czochralski method (CZ method) or a magnetic field application type CZ method. Next, after growing the tail part following the straight body part in the range of 50 mm to 150 mm, the single crystal rod is separated from the silicon melt. Next, after separating the single crystal rod from the silicon melt, the single crystal rod is maintained by maintaining the crystal position directly above the silicon melt while turning off the heater power to the growth apparatus and lowering the furnace temperature. The rod is cooled, and then the cooled single crystal rod is taken out from the growth apparatus.

  Subsequently, the straight body portion of the obtained single crystal rod is cut into a fixed length of about 150 mm to 300 mm to form a block. Normally, the silicon electrode plate is used up to the region where the crystal habit line of the straight body portion is generated. Furthermore, the silicon electrode plate was produced by slicing the block body to a predetermined thickness. However, when blocking the straight body portion of the obtained silicon single crystal rod, when the region having the habit line and including the etch pit portion is cut, a large crack occurs in the single crystal, There was a problem that the product rate of the silicon electrode plate without cracking from the silicon single crystal rod as the base material was low.

  An object of the present invention is to provide a method for producing a silicon single crystal that can prevent the occurrence of crystal cracking during cutting and improve the productization rate of a silicon electrode plate.

As shown in FIG. 1, the invention according to claim 1 is a method in which a silicon raw material stored in a quartz crucible 13 provided in a CZ furnace is heated by an electric heater 18 and melted from a molten silicon melt 12. A process of pulling up the silicon single crystal rod 25 of a length while being surrounded by a cylindrical heat shield member 36, and silicon pulled up to a predetermined length while being heated by a heater 18, as shown in FIG. The step of separating the silicon melt 12 and the silicon single crystal rod 25 by stopping the pulling of the single crystal rod 25 and lowering the crucible 13 temporarily, and the separated silicon single crystal rod 25 as shown in FIG. The crucible 13 is lowered together to a predetermined position so that the lower part of the silicon single crystal rod 25 is gradually exposed from the lower end of the heat shielding member 36 and the exposed lower part of the silicon single crystal rod 25 is exposed. A method for manufacturing a silicon single crystal and a step of heat-treating a predetermined time by directly exposed to radiant heat over data 18.
The invention according to claim 2 is the manufacturing method according to claim 1, further comprising the step of maintaining the power of the heater 18 in the CZ furnace by cutting the power of the silicon single crystal rod 25 heat-treated for a predetermined time. It is.

  Conventionally, when a silicon single crystal rod separated from a silicon melt is cooled, the pulled silicon single crystal rod is covered with a heat shielding member and gradually cooled while blocking the radiant heat of the heater. In the method, since the residual stress existing inside the obtained single crystal rod is large, it is considered that crystal cracking occurs at the time of cutting due to this residual stress. Especially when used as a silicon electrode plate, it uses up to the region where the crystal habit line of the straight body portion is generated. Therefore, the region including the crystal habit line and including the etch pit portion must be cut. This effect will be even greater. On the other hand, in the method for producing a silicon single crystal according to the present invention, the lower part of the silicon single crystal bar having a large residual stress existing therein is gradually exposed from the lower end of the heat shielding member, and the exposed lower part of the silicon single crystal bar is A heat treatment process is performed to directly expose to the radiant heat of the heater. This heat treatment process releases residual stress that exists inside the crystal below the silicon single crystal rod, thus preventing the occurrence of crystal cracking due to cutting when producing a silicon electrode plate from the obtained silicon single crystal rod. It is possible to improve the production rate of the silicon electrode plate.

The invention according to claim 3 is the invention according to claim 1, wherein the heat treatment to the lower part of the silicon single crystal rod 25 is performed while lowering the silicon single crystal rod 25, and the heating by the heater 18 is changed from a high temperature to a low temperature. It is a manufacturing method performed while lowering the temperature stepwise or continuously.
In the invention according to claim 3, by lowering the silicon single crystal rod and performing heating by the heater stepwise or continuously while lowering the temperature, the lower portion of the silicon single crystal rod has a gentle temperature profile. Since it is gradually cooled, the residual stress existing in the lower part of the silicon single crystal rod can be released more.

The invention according to claim 4 is the method according to claim 1, wherein the heat treatment of the lower part of the silicon single crystal rod is performed at a heater temperature of 1000 to 1400 ° C. for 120 to 180 minutes.
The invention according to claim 5 is the invention according to claim 1, wherein the predetermined length of the silicon single crystal rod is 70 to 120 cm, and the lower portion of the silicon single crystal rod is 0 from the lower end of the silicon single crystal rod. It is a manufacturing method which is ~ 40cm.
The invention according to claim 6 is the manufacturing method according to claim 1, wherein the silicon single crystal rod has a diameter of 240 to 450 mm.

  The method for producing a silicon single crystal according to the present invention is a heat treatment step in which the lower part of a silicon single crystal rod having a large residual stress is gradually exposed from the lower end of the heat shielding member, and the exposed lower part is directly exposed to the radiant heat of the heater. Since the residual stress existing inside the crystal at the bottom of this silicon single crystal rod is released, the crystal cracking due to cutting is generated when the silicon electrode plate is produced from the obtained silicon single crystal rod. This can be prevented, and the production rate of the silicon electrode plate can be improved.

Next, the best mode for carrying out the present invention will be described with reference to the drawings.
FIG. 1 shows a CZ furnace for carrying out the method for producing a silicon single crystal of the present invention. A quartz crucible 13 for storing the silicon melt 12 is provided in the chamber 11 of the CZ furnace 10, and the outer peripheral surface of the quartz crucible 13 is covered with a graphite susceptor 14. The lower surface of the quartz crucible 13 is fixed to the upper end of the support shaft 16 via the graphite susceptor 14, and the lower portion of the support shaft 16 is connected to the crucible driving means 17. Although not shown, the crucible driving means 17 has a first rotating motor for rotating the quartz crucible 13 and a lifting motor for moving the quartz crucible 13 up and down, and the quartz crucible 13 can be rotated in a predetermined direction by these motors. At the same time, it is movable in the vertical direction. The outer peripheral surface of the quartz crucible 13 is surrounded by an electric heater 18 at a predetermined interval from the quartz crucible 13, and the electric heater 18 is surrounded by a heat retaining cylinder 19. The electric heater 18 heats and melts the silicon raw material charged in the quartz crucible 13 to form the silicon melt 12.

A cylindrical casing 21 is connected to the upper end of the chamber 11. The casing 21 is provided with a pulling means 22. The pulling means 22 is a pulling head (not shown) provided at the upper end of the casing 21 so as to be turnable in a horizontal state, a second rotating motor (not shown) for rotating the head, and a quartz crucible 13 from the head. And a pulling motor (not shown) that is provided in the head and winds or feeds the wire cable 23. A seed crystal 24 is attached to the lower end of the wire cable 23 to immerse the silicon single crystal rod 25 in the silicon melt 12.
Further, a gas supply / discharge means 28 for supplying an inert gas to the silicon single crystal rod side of the chamber 11 and discharging the inert gas from the crucible inner peripheral surface side of the chamber 11 is connected to the chamber 11. The gas supply / discharge means 28 has one end connected to the peripheral wall of the casing 21 and the other end connected to a tank (not shown) for storing the inert gas, and one end connected to the lower wall of the chamber 11. The other end has a discharge pipe 30 connected to a vacuum pump (not shown). The supply pipe 29 and the discharge pipe 30 are respectively provided with first and second flow rate adjusting valves 31 and 32 for adjusting the flow rate of the inert gas flowing through the pipes 29 and 30.

  On the other hand, an encoder (not shown) is provided on the output shaft (not shown) of the pulling motor, and an encoder (not shown) for detecting the raising / lowering position of the support shaft 16 is provided on the crucible driving means 17. Each detection output of the two encoders is connected to a control input of a controller (not shown), and the control output of the controller is connected to a lifting motor of the pulling means 22 and a lifting motor of the crucible driving means. The controller is also provided with a memory (not shown), and the memory stores the winding length of the wire cable 23 with respect to the detection output of the encoder, that is, the pulling length of the silicon single crystal rod 25 as a first map. . Further, the memory stores the liquid level of the silicon melt 12 in the quartz crucible 13 with respect to the pulled length of the silicon single crystal rod 25 as a second map. The controller is configured to control the raising / lowering motor of the crucible driving means 17 so as to always keep the liquid level of the silicon melt 12 in the quartz crucible 13 at a constant level based on the detection output of the encoder in the pulling motor. Is done.

  Between the outer peripheral surface of the silicon single crystal rod 25 and the inner peripheral surface of the quartz crucible 13, a heat shielding member 36 surrounding the outer peripheral surface of the silicon single crystal rod 25 is provided. The heat shield member 36 has a cylindrical portion 37 that is formed in a cylindrical shape and shields radiant heat from the electric heater 18, and a flange portion 38 that is connected to the upper edge of the cylindrical portion 37 and projects outward in a substantially horizontal direction. . By placing the flange portion 38 on the heat insulating cylinder 19, the heat shielding member 36 is fixed in the chamber 11 so that the lower edge of the cylinder portion 37 is positioned a predetermined distance above the surface of the silicon melt 12. The A bulging portion 39 that bulges in the direction of the tube is provided at the bottom of the tube portion 37.

A method for manufacturing a silicon single crystal rod using the CZ furnace configured as described above will be described.
As shown in FIG. 1, a silicon raw material is put into a quartz crucible 13, and this silicon raw material is heated and melted by an electric heater 18 to form a silicon melt 12. Examples of the silicon raw material include high-purity silicon polycrystal. Further, a dopant impurity may be introduced into the quartz crucible as necessary together with the silicon polycrystal. Subsequently, the quartz crucible 13 is rotated at a predetermined speed via the support shaft 16 by the crucible driving means 17. Then, the wire cable 23 is fed out by a pulling motor (not shown) of the rotary pulling means to lower the seed crystal 24, and the tip of the seed crystal 24 is brought into contact with the silicon melt 12. Then, while rotating the seed crystal 24 at a predetermined rotational speed in a direction opposite to that of the quartz crucible 13, the seed crystal 24 is gradually pulled up, whereby a silicon single crystal rod 25 having a predetermined length is formed below the seed crystal 24. Develop.

  In growing the silicon single crystal rod 25, first, after the seed crystal 24 brought into contact with the silicon melt is melted, the pulling is started to form the seed constricted portion 25a, the crystal diameter is gradually increased, and the cone portion 25b, The shoulder portion 25c is formed, and the process proceeds to pulling up the regular straight body portion 25d. The axial length of the straight body portion 25d is preferably 50 to 100 cm. The crystal growth rate is optimized by controlling the pulling rate and the melt temperature while taking into account the height of the melt surface that decreases with pulling growth. After the straight body portion 25d is formed, the crystal diameter is gradually reduced to form the tail portion 25e. The tail portion is grown in the range of 50 mm to 150 mm. The diameter of the silicon single crystal rod 25 having a predetermined length grown in this way is preferably 240 to 450 mm.

  Next, as shown in FIG. 2, after the tail portion 25e is formed, the silicon single crystal rod 25 is lifted by stopping the pulling motor (not shown) of the rotary pulling means while being heated by the electric heater 18. And the quartz crucible 13 is temporarily lowered by the crucible driving means 17 via the support shaft 16 to separate the silicon melt 12 and the silicon single crystal rod 25 from each other. The length from the straight body portion 25d to the tail portion 25e constituting the separated silicon single crystal rod 25 is preferably 70 to 120 cm for reasons of manufacturing cost. As shown in FIG. 4, for example, the straight body portion 25d of the silicon single crystal rod 25 having a diameter of 400 mm and a length of 60 cm from the straight body portion 25d to the tail portion 25e is a single crystal region from the shoulder portion 25c to about 100 mm. The single crystal region 25g is followed by a crystal line containing region 25h up to about 400 mm and a crystal wall line disappearing region 25i up to the tail portion 25e. When this habit line containing region 25h is cut and the cut surface is dash or secco etched, etch pits appear. The regions used as the silicon electrode plate are the single crystal region 25g and the habit line containing region 25h.

  Subsequently, as shown in FIG. 3, the separated silicon single crystal rod 25 and the quartz crucible 13 are lowered together to a predetermined position while being heated by the electric heater 18. The descending speed of the silicon single crystal rod 25 and the quartz crucible 13 depends on the diameter of the silicon single crystal rod 25 to be grown and the length in the axial direction, but is preferably in the range of 1.0 to 2.5 mm / min. The range of 0.5 to 2.0 mm / min is more preferable. If it is less than the lower limit, a defect of cracking at the crystal cutting stage occurs due to insufficient heat treatment, and if it exceeds the upper limit value, the crystal separation part melts due to excessive heat treatment, causing a defect of cracking at the crystal processing stage. The separated silicon single crystal rod 25 is lowered by feeding the wire cable 23 by a pulling motor (not shown) of the rotary pulling means, and the quartz crucible 13 is lowered by a lifting motor (not shown) of the crucible driving means 17. 16 is performed. By this downward movement, the lower part of the silicon single crystal rod 25 is gradually exposed from the bulging portion 39 located at the lower end of the heat shielding member 36 while maintaining a certain distance between the silicon single crystal rod 25 and the silicon melt 12. The exposed portion of the lower portion of the crystal rod 25 is directly exposed to the radiant heat of the electric heater 18. Thus, the heat treatment for the lower portion of the silicon single crystal rod 25 is performed while the silicon single crystal rod 25 is lowered. The lower part of the silicon single crystal rod exposed from the lower end of the heat shielding member 36 is preferably 20 to 50 cm from the lower end of the silicon single crystal bar of the separation part 25f, and is more preferably 30 to 40 cm. If it is less than the lower limit, the residual stress cannot be relieved due to insufficient heat treatment range, causing a defect of cracking in the crystal processing stage. Even if the upper limit is exceeded, there is no particular problem, but this is a limitation on the device structure. The heat treatment of the lower portion of the silicon single crystal rod 25 is preferably performed at a heater temperature of 1000 to 1400 ° C. for 120 to 180 minutes, and more preferably at a heater temperature of 1100 to 1300 ° C. for 120 to 180 minutes. The reason why the heater temperature is in the range of 1000 to 1400 ° C. is that if it is less than the lower limit value, rapid cooling occurs and residual stress exists in the single crystal rod. This is because the surface of the rod may melt again. The reason why the heat treatment time is in the range of 120 to 180 minutes is that if the heat treatment time is less than the lower limit value, the heat treatment cannot be performed sufficiently and residual stress exists in the single crystal rod, which exceeds the upper limit value. However, the effect is not changed, but the manufacturing cost is increased.

  Further, the heating by the electric heater 18 may be performed while decreasing the temperature stepwise or continuously from a high temperature to a low temperature. Specifically, the heating temperature by the electric heater is continuously lowered immediately after the silicon single crystal rod 25 starts to descend, and the lower portion of the silicon single crystal rod 25 is completely exposed from the lower end of the heat shielding member 36 and lowered. The heating by the electric heater may be stopped before the operation is stopped. Further, immediately after the silicon single crystal rod 25 starts to descend, the heating temperature by the electric heater is kept constant, and when the single crystal rod descends to a desired position, the heating temperature by the electric heater is lowered to a predetermined temperature. In addition, heating may be performed in stages so as to keep the lowered temperature constant.

  Furthermore, the electric power of the electric heater 18 is cut off and maintained in the CZ furnace 10 at the lower part of the silicon single crystal rod 25 heat-treated for a predetermined time. The single crystal rod is cooled by lowering the furnace temperature, and the cooled single crystal rod is taken out from the CZ furnace. The straight body portion 25d of the silicon single crystal rod 25 thus obtained is cut into a fixed length of about 150 mm to 300 mm and blocked. In the silicon single crystal rod obtained through the manufacturing method of the present invention, the residual stress that causes cracking in the cutting process is released, so when the straight body portion of the single crystal rod is blocked, Even if it is cut in the region 25h including the etch pit portion, no large cracks are generated in the single crystal. Therefore, the product rate of silicon electrode plates can be improved.

Next, examples of the present invention will be described in detail together with comparative examples.
<Example 1>
A silicon single crystal rod was manufactured using the CZ furnace shown in FIG. Specifically, first, the inside of the chamber 11 was depressurized to 25 torr (about 3.3 kPa), and Ar gas was continuously introduced at a rate of 100 l / min. Next, silicon raw material for crystal and boron were put into the quartz crucible 13, the heater power of the electric heater 18 was set to 160 kW, and the silicon raw material and boron were melted to obtain a silicon melt 12. Subsequently, the crucible driving means 17 rotates the quartz crucible 13 through the support shaft 16 at a speed of 6 rpm, the wire cable 23 is fed out by a pulling motor (not shown) of the rotary pulling means, and the seed crystal 24 is the quartz crucible 13. The seed crystal 24 was lowered while rotating in the reverse direction at a rotational speed of 6 rpm, and the tip of the seed crystal 24 was brought into contact with the silicon melt 12. After the tip of the seed crystal 24 has melted, the seed crystal 24 is gradually pulled up to form a seed squeezed portion 25a, a cone portion 25b, and a shoulder portion 25c. Further, a straight barrel portion having a diameter of 340 mm and an axial length of 760 mm was formed. After the straight barrel portion was formed, the tail portion 25e was formed by narrowing the crystal diameter to about 300 mm with an axial length of 50 mm.

  Next, as shown in FIG. 2, after the tail portion 25e is formed, the pulling of the silicon single crystal rod 25 is stopped, and the quartz crucible 13 is temporarily lowered to separate the silicon melt 12 and the silicon single crystal rod 25 from each other. It was. The distance between the separated silicon single crystal rod 25 and the surface of the silicon melt 12 was about 80 mm.

  Next, as shown in FIG. 3, the silicon single crystal rod 25 and the quartz crucible 13 are lowered together at a descending speed of 1.5 mm / min, and the lower portion of the silicon single crystal rod 25 is gradually lowered from the lower end of the heat shielding member 36. Then, the lower part of the exposed silicon single crystal rod 25 was directly exposed to the radiant heat of the electric heater 18 for heat treatment for a predetermined time. The lowering of the silicon single crystal rod 25 and the quartz crucible 13 stopped about 135 minutes after being lowered by about 200 mm. Further, the output of the heater power of the electric heater 18 was reduced from 160 kW before crystal separation to 100 kW, the heater temperature was set to 1300 ° C., and this heater power was held for 60 minutes. After 60 minutes, the heater power was further reduced to 50 kW, the heater temperature was set to 1100 ° C., the heater power was held for 60 minutes, and the heater power was cut after the hold. The relationship between the descending speed of the quartz crucible and the silicon single crystal rod and the heater power in this heat treatment step is shown in FIG. After the heater power was cut off, the silicon single crystal rod 25 was cooled by holding for 12 hours while maintaining the silicon single crystal rod 25 at the lowered position. After cooling, the silicon single crystal rod 25 was taken out of the CZ furnace, and the straight body portion 25d of the silicon single crystal rod 25 was cut into a fixed length of about 150 mm to 300 mm and blocked. In the block formation, even when cutting was performed in the region 25h having crystal habit lines and including the etch pit portion, no large cracks were generated in the single crystal. Moreover, it was able to cut | disconnect without abnormality also about each cutting | disconnection site | part.

<Comparative Example 1>
In the same manner as in Example 1, the straight body portion 25d was pulled up, and after the formation of the straight body portion, the tail portion 25e was formed by narrowing the crystal diameter to about 250 mm with an axial length of 150 mm. After the tail portion 25e was formed, the pulling of the silicon single crystal rod 25 was stopped, and the quartz crucible 13 was temporarily lowered to separate the silicon melt 12 and the silicon single crystal rod 25 from each other. After the silicon single crystal rod 25 was separated from the silicon melt 12, the heater power was cut while maintaining the crystal position of the silicon single crystal rod 25 directly above the silicon melt 12. This state was maintained for 12 hours to cool the silicon single crystal rod 25. After cooling, the silicon single crystal rod 25 was taken out of the CZ furnace, and the straight body portion 25d of the silicon single crystal rod 25 was cut into a fixed length of about 150 mm to 300 mm and blocked. In the block formation, a large crack was generated in the single crystal when it was cut in the region 25h having the habit line and including the etch pit portion. Similarly, silicon single crystal rods were manufactured a plurality of times and attempted to be blocked. When all single crystal rods were cut in the region 25h having crystal habit lines and including etch pits, single crystals were obtained. A big crack has occurred.

The figure which shows the process of pulling up the silicon single crystal rod from the silicon melt in the production method of the present invention. The figure which shows the process of isolate | separating a silicon melt and a silicon single crystal rod in the manufacturing method of this invention. The figure which shows the process of heat-processing the lower part of the silicon single crystal rod in the manufacturing method of this invention. The figure which shows the silicon single crystal rod obtained by the manufacturing method of this invention. The figure which shows the relationship between the descending speed of a quartz crucible and a silicon single crystal rod in a heat treatment process, and heater electric power. The cross-sectional block diagram of a general plasma etching apparatus.

Explanation of symbols

10 CZ furnace 12 Silicon melt 13 Quartz crucible 18 Electric heater 25 Silicon single crystal rod 36 Heat shielding member

Claims (6)

A silicon single crystal having a predetermined length from a silicon melt (12) melted by heating a silicon raw material stored in a quartz crucible (13) provided in a CZ furnace (10) with an electric heater (18). Pulling up the rod (25) while being surrounded by the cylindrical heat shield member (36);
By stopping the pulling of the silicon single crystal rod (25) pulled up to the predetermined length while being heated by the heater (18) and temporarily lowering the crucible (13), the silicon melt is melted. Separating the liquid (12) and the silicon single crystal rod (25);
The separated silicon single crystal rod (25) and the crucible (13) are lowered together to a predetermined position, and the lower portion of the silicon single crystal rod (25) is gradually exposed from the lower end of the heat shielding member (36). And a heat treatment for a predetermined time by directly exposing a lower portion of the exposed silicon single crystal rod (25) to radiant heat of the heater (18).   The manufacturing method according to claim 1, further comprising the step of maintaining the inside of the CZ furnace (10) by cutting off the power of the heater (18) under the silicon single crystal rod (25) heat-treated for a predetermined time. Heat treatment to the lower part of the silicon single crystal rod (25) is performed while lowering the silicon single crystal rod (25),
The manufacturing method according to claim 1, wherein the heating by the heater (18) is performed while gradually or continuously decreasing the temperature from a high temperature to a low temperature.   The manufacturing method according to claim 1, wherein the heat treatment of the lower part of the silicon single crystal rod (25) is performed at a heater temperature of 1000 to 1400 ° C for 120 to 180 minutes.   The manufacturing method according to claim 1, wherein the predetermined length of the silicon single crystal rod (25) is 70 to 120 cm, and the lower portion of the silicon single crystal rod is 0 to 40 cm from the lower end of the silicon single crystal rod.   The method according to claim 1, wherein the silicon single crystal rod (25) has a diameter of 240 to 450 mm.

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