JP4457584B2 - Method for producing single crystal and single crystal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a single crystal by the Czochralski method, and more particularly to a method for producing a single crystal having a predetermined crystal diameter and a desired defect region.
[0002]
[Prior art]
As a single crystal used as a substrate of a semiconductor device, for example, there is a silicon single crystal or the like, and it is mainly manufactured by a Czochralski method (hereinafter abbreviated as CZ method). In recent years, high integration has been promoted in semiconductor devices, and miniaturization of elements has progressed. Accordingly, the problem of grown-in defects introduced during single crystal growth has become more important.
[0003]
Here, the grow-in defect will be described with reference to FIG.
In general, when a silicon single crystal is grown, if the crystal growth rate V (crystal pulling rate) is relatively high, FPD (Flow Pattern Defect), which is caused by voids in which hole-type point defects are gathered, is assumed. Grown-in defects such as COP (Crystal Originated Particle) and the like exist in high density throughout the crystal diameter direction. A region where defects due to these voids exist is called a V (vacancy) region.
[0004]
Further, when the crystal growth rate is lowered, an OSF (Oxidation Induced Stacking Fault) region is generated in a ring shape from the periphery of the crystal as the growth rate is lowered, and when the growth rate is further lowered, the OSF is reduced. The ring shrinks to the center of the wafer and disappears. On the other hand, when the growth rate is further reduced, defects such as LSEPD (Large Secco Etch Pit Defect) and LFPD (Large Flow Pattern Defect), which are considered to be caused by dislocation loops in which interstitial silicon has gathered, exist at low density. The region where the defect exists is called an I (Interstitial) region.
[0005]
In recent years, it has been discovered that there is an area outside the OSF ring between the V region and the I region, where there are no defects such as FPD and COP caused by voids and no defects such as LSEPD and LFPD caused by interstitial silicon. This region is called an N (neutral) region. Further, this N region is further classified into an Nv region (region with many vacancies) adjacent to the outside of the OSF ring and a Ni region (region with a lot of interstitial silicon) adjacent to the I region. In the Nv region, It is known that the amount of precipitated oxygen is large when the thermal oxidation treatment is performed, and there is almost no oxygen precipitation in the Ni region.
[0006]
Furthermore, after thermal oxidation treatment, it has been found that there is a region (hereinafter referred to as Cu deposition defect region) in which defects detected by Cu deposition treatment are remarkably generated in a part of the Nv region where oxygen precipitation is likely to occur. This has been found to cause deterioration of electrical characteristics such as oxide film breakdown voltage characteristics.
[0007]
These grow-in defects are caused by a pulling rate V (mm / min) when growing a single crystal and a crystal temperature gradient G (° C / mm) in the pulling axial direction between 1400 ° C and the melting point of silicon near the solid-liquid interface. Ratio V / G (mm²The introduction amount is considered to be determined by a parameter of / ° C./min) (see, for example, Non-Patent Document 1). That is, a single crystal having a desired defect region or a desired defect-free region can be manufactured by growing a single crystal while V / G is controlled to be constant at a predetermined value.
[0008]
For example, in Patent Document 1, when a silicon single crystal is grown, the V / G value is within a predetermined range (for example, 0.112 to 0.142 mm) at the crystal center.²It has been shown that a silicon single crystal wafer free from defects due to voids and defects due to dislocation loops can be obtained by pulling up the single crystal under the control of / ° C./min). In recent years, there has been an increasing demand for defect-free crystals in the N region that do not include the Cu deposition defect region, and the manufacture of single crystals that pull up the single crystal while controlling the V / G to a predetermined defect-free region with high accuracy. Has been required.
[0009]
In general, the crystal temperature gradient G in the pulling axis direction is uniquely determined by HZ (hot zone: in-furnace structure) of a single crystal pulling apparatus in which single crystals are grown. However, since it is extremely difficult to change HZ during pulling of the single crystal, when the single crystal is grown by controlling V / G as described above, the crystal temperature gradient G is controlled during pulling of the single crystal. However, a single crystal having a desired defect region is manufactured by controlling the V / G value by adjusting the pulling rate V.
[0010]
Further, in the conventional production of a single crystal, in order to control the diameter of the single crystal to be grown, the temperature of the raw material melt is adjusted by adjusting the pulling rate of the single crystal or changing the power of the heater for heating the raw material melt. It has been done to adjust. However, in the case of growing a single crystal having a desired defect region by controlling the V / G value as described above, the V / G is controlled by adjusting the pulling speed and at the same time the diameter control of the single crystal. However, if the pulling speed is greatly changed in order to make the crystal diameter a desired size at this time, the defect region of the pulled single crystal changes, and the single crystal is There was a problem that it was not possible to grow in the area, resulting in a decrease in yield.
[0011]
Therefore, conventionally, in order to improve such a problem as much as possible, a single crystal can be grown in a desired defect region while suppressing fluctuations in the crystal pulling rate, and a heater is used to control the crystal diameter to a desired value. The temperature of the raw material melt was adjusted by changing the power. However, even if the single crystal is grown in this way, it is very difficult to grow the entire single crystal straight body portion with a predetermined diameter and to have a desired defect region. In order to control the temperature of the raw material melt in order to control the crystal diameter, it is necessary to change the set temperature pattern of the raw material melt for each single crystal pulling device and each single crystal production batch. Therefore, it is necessary to adjust the temperature pattern for each single crystal pulling apparatus or each manufacturing batch, and it takes a lot of labor to manufacture a single crystal in a desired defect region while controlling the diameter. The burden on the work was very heavy.
[0012]
[Patent Document 1]
JP-A-11-147786
[Non-Patent Document 1]
V. V. Voronkov, Journal of Crystal Growth, 59 (1982), 625-643
[0013]
[Problems to be solved by the invention]
Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to stabilize the single crystal diameter control and V / G control when growing the single crystal by the CZ method. It is an object of the present invention to provide a method for producing a single crystal which can be produced easily and can produce a single crystal having a predetermined crystal diameter and a desired defect region easily and with a high yield.
[0014]
[Means for Solving the Problems]
  In order to achieve the above object, according to the present invention, in a method for producing a single crystal by pulling it up from a raw material melt in a chamber by the Czochralski method, the single crystal is directly grown when the single crystal is grown. The diameter of the straight body of the single crystal is expressed as V (mm / min) as the pulling speed when growing the body and G (° C./mm) as the crystal temperature gradient in the pulling axis direction near the solid-liquid interface. The single crystal is pulled while controlling / changing the pulling speed V so that becomes a predetermined value, and the crystal temperature gradient G is controlled by changing the pulling condition of the single crystal according to the fluctuation of the pulling speed V. Ratio V / G (mm of pulling speed V and crystal temperature gradient G²/.Degree. C./min) is controlled so that a single crystal having a desired defect region can be grown..
[0015]
Thus, when a single crystal is grown by the CZ method, the crystal diameter can be stably controlled by controlling and changing the pulling rate V, and at the same time, other single crystals can be controlled according to the variation of V. By controlling the crystal temperature gradient G by changing the pulling conditions, the V / G can be stably controlled so that a single crystal having a desired defect region can be grown. Then, by growing the single crystal while performing the diameter control and the V / G control in this manner, the single crystal has a predetermined crystal diameter over the entire straight body of the single crystal, and a desired defect region is formed. A high-quality single crystal can be easily manufactured with a high yield.
[0016]
  At this time, the single crystal pulling conditions to be changed when growing the single crystal are the distance between the melt surface of the raw material melt and the heat shield member disposed opposite to the raw material melt surface in the chamber, and the single crystal pulling condition. The rotational speed of the single crystal when pulling up the crystal, the rotational speed of the crucible containing the raw material melt, the flow rate of the inert gas introduced into the chamber, the position of the heater for heating the raw material melt, the inside of the chamber Preferably, at least one of a pressure, a magnetic field strength of a magnetic field applied to the raw material melt, and a relative distance between the raw material melt surface and the magnetic field center of the magnetic field applied to the raw material melt..
[0017]
Thus, when growing a single crystal, the crystal temperature gradient G can be easily controlled in accordance with fluctuations in the pulling rate V by changing at least one of the single crystal pulling conditions shown above. Accordingly, V / G can be stably controlled with high accuracy so that a single crystal having a desired defect region can be grown.
[0018]
  In this case, it is preferable to control the V / G so that the defect region of the single crystal to be grown becomes an N region over the entire surface in the radial direction..
  In this way, by controlling the V / G so that the defect region of the single crystal becomes the N region in the entire radial direction, defects caused by voids such as FPD and COP in the single crystal straight body portion can also be caused by LSEPD, LFPD. It is possible to produce a very high quality single crystal with a high yield without defects such as dislocation loops and the like, and with a crystal diameter controlled with high accuracy.
[0019]
  The diameter of the straight body of the single crystal can be 200 mm or more..
  The method for producing a single crystal of the present invention can be very effectively applied to the production of a large-diameter single crystal having a diameter of 200 mm or more, and a single crystal straight body portion that has been difficult to produce conventionally. Thus, a large-diameter single crystal having a diameter of 200 mm or more, which becomes a desired defect region, can be easily and very stably manufactured.
[0020]
  Furthermore, the single crystal to be manufactured can be a silicon single crystal..
  As described above, the method for producing a single crystal of the present invention can be particularly preferably used for producing a silicon single crystal. By producing a silicon single crystal according to the present invention, the diameter of the silicon single crystal can be increased during the growth of the silicon single crystal. Control and V / G control can be performed stably, and a high-quality silicon single crystal having a predetermined crystal diameter and having a desired defect region over the entire straight body can be easily obtained. And it can manufacture with a high yield.
[0021]
  And according to this invention, the single crystal manufactured by the manufacturing method of the said single crystal is provided..
  The single crystal produced according to the present invention can be a very high quality single crystal having a predetermined crystal diameter uniformly over the entire area of the single crystal straight body and having a desired defect region.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, although an embodiment is described about the present invention, the present invention is not limited to these.
The inventors of the present invention have repeatedly studied a method capable of easily and high yielding a single crystal having a predetermined crystal diameter and a desired defect region by the CZ method, and increasing the pulling speed V when pulling up the single crystal. If the diameter can be controlled by controlling and changing, and the crystal temperature gradient G in the pulling axis direction between the melting point of silicon near the solid-liquid interface and 1400 ° C. can be controlled during pulling of the single crystal, For control, it was considered that V / G can be controlled even if the pulling speed V is greatly changed, and a single crystal having a predetermined crystal diameter and a desired defect region can be easily grown with a high yield.
[0023]
Therefore, as a result of further experiments and examinations, the present inventors, as a result, a heat shielding member disposed so as to face the melt surface of the raw material melt and the raw material melt surface when the single crystal is grown by the CZ method, Distance, rotation speed of the single crystal for rotating the single crystal, rotation speed of the crucible containing the raw material melt, flow rate of the inert gas introduced into the chamber, position of the heater for heating the raw material melt, Pay attention to the single crystal pulling conditions such as pressure, magnetic field strength of the magnetic field applied to the raw material melt, and relative distance between the raw material melt surface and the magnetic field center of the magnetic field applied to the raw material melt. It has been found that the crystal temperature gradient G in the pulling axis direction between the melting point of silicon near the solid-liquid interface and 1400 ° C. can be controlled by intentionally changing the single crystal pulling. Pull The V / G was found to be controlled with high accuracy in a desired defect region by also varying the lower speed V to alter or control the crystal temperature gradient G.
[0024]
In addition, the present inventors have developed a comprehensive heat transfer analysis software FEMAG (F. Dupret, P. Nicodeme, Y. Ryckmans, P. Waters, and M. J. Crochet, Int. J. Heat Mass Transfer, 33, 1849 (1990). )), A simulation analysis was performed on the change in the crystal temperature gradient G when the single crystal pulling conditions described above were changed when growing the single crystal. 1 to 8, changes in G when the distance L1 between the raw material melt surface and the heat shield member is changed during pulling of the single crystal, changes in G when the rotation speed of the single crystal is changed, The change in G when the rotational speed of the crucible is changed, the change in G when the flow rate of the inert gas is changed, the position of the heat generation center of the heater and the raw material melt surface when the heater position is changed Change in G relative to the relative distance L2, change in G when the pressure in the chamber is changed, change in G when the magnetic field strength applied to the raw material melt is changed, applied to the raw material melt surface and the raw material melt An example of the result of simulation analysis for each change in G when the relative distance L3 of the magnetic field to be performed is changed is shown.
[0025]
As shown in FIG. 1 to FIG. 8, as a result of simulation analysis, it is clear that the crystal temperature gradient G changes by changing each pulling condition shown above. Decrease the distance L1 between the surface and the heat shield member, increase the rotation speed of the single crystal, decrease the rotation speed of the crucible, increase the flow rate of the inert gas, the heat generation center position of the heater and the raw material melt surface The crystal temperature gradient is obtained by changing the heater position so that the relative distance L2 is increased, decreasing the pressure in the chamber, increasing the magnetic field strength, or decreasing the relative distance L3 between the raw material melt surface and the magnetic field center. G can be increased, and on the other hand, the crystal temperature gradient G can be reduced by changing each single crystal pulling condition with the above increase and decrease reversed. It was bought.
[0026]
Furthermore, when the time (responsiveness) until the crystal temperature gradient G changes when the above single crystal pulling conditions are changed during single crystal pulling is investigated, When the distance L1 between the heat shield members, the rotation speed of the single crystal, and the flow rate of the inert gas are changed, the crystal temperature gradient G also changes immediately according to the change of the pulling conditions, and quick response It was found that the crystal temperature gradient G is very suitable for the fluctuation of the pulling rate V in a relatively short period. In addition, when the crucible rotation speed, the heater position, the pressure in the chamber, the magnetic field strength, and the relative distance L3 between the raw material melt surface and the magnetic field center are changed, the crystal temperature gradient G changes gently. It has been found that it is suitable for controlling the crystal temperature gradient G with respect to the fluctuation of the pulling speed V having a relatively long period. It has been found that if these are controlled in combination, V / G can be controlled within a predetermined value with high accuracy against various fluctuations in the pulling speed V.
[0027]
The present invention utilizes the relationship between the single crystal pulling condition during the pulling of the single crystal and the crystal temperature gradient G as described above to control the single crystal diameter and V / G when growing the single crystal. It can be performed very stably.
That is, according to the method for producing a single crystal of the present invention, when the single crystal is grown by the CZ method, the single crystal is pulled while controlling and changing the pulling speed V so that the diameter of the single crystal straight body portion becomes a predetermined value. In addition, the crystal temperature gradient G is controlled by changing the single crystal pulling conditions according to the fluctuation of the pulling speed V, and V / G is set to a desired value so that a single crystal having a desired defect region can be grown. It is characterized by control.
[0028]
Hereinafter, although the manufacturing method of the single crystal of this invention is demonstrated in detail, referring drawings, this invention is not limited to this.
The single crystal pulling apparatus used in the method for producing a single crystal according to the present invention includes a distance L1 between the raw material melt surface and the heat shield member during the pulling of the single crystal, the rotation speed of the single crystal, the rotation speed of the crucible, and an inert gas. Flow rate, heater position, chamber pressure, magnetic field strength applied to the raw material melt, and relative distance L3 between the raw material melt surface and the magnetic field center applied to the raw material melt. Although it will not specifically limit if crystal pulling conditions can be changed, For example, a single crystal pulling apparatus as shown in FIG. 9 can be used. First, a single crystal pulling apparatus that can be used when carrying out the method for producing a single crystal of the present invention will be described with reference to FIG.
[0029]
In the single crystal pulling apparatus 20 shown in FIG. 9, a quartz crucible 5 containing a raw material melt 4 and a graphite crucible 6 protecting the quartz crucible 5 are rotated and moved up and down by a crucible driving mechanism 21 in a main chamber 1. The heater 7 and the heat insulating material 8 are disposed so as to be freely supported by the holding shaft 13 and surround the crucibles 5 and 6, and further, heater driving means 22 is provided so that the position of the heater 7 can be adjusted. It has been.
[0030]
A pulling chamber 2 for accommodating and taking out the grown single crystal 3 is connected to the upper part of the main chamber 1, and a pulling mechanism 17 for pulling up the single crystal 3 while rotating it with a wire 14 is connected to the upper part of the pulling chamber 2. Is provided.
[0031]
Further, a gas rectifying cylinder 11 is provided inside the main chamber 1, and a heat shield member 12 is installed at the lower part of the gas rectifying cylinder 11 so as to face the raw material melt 4. The radiation from the surface of the material is cut and the surface of the raw material melt 4 is kept warm. Further, on the upper part of the gas rectifying cylinder 11, a heat shielding member driving means 23 capable of adjusting the position of the heat shielding member 12 up and down by raising and lowering the gas rectifying cylinder 11 is installed. In the present invention, the shape, material, and the like of the heat shield member 12 are not particularly limited, and can be changed as appropriate. Furthermore, the heat shield member 12 of the present invention may be any member as long as it is disposed so as to face the melt surface, and is not necessarily limited to the member installed at the lower portion of the gas rectifying cylinder as described above.
[0032]
An inert gas such as argon gas can be introduced from the gas inlet 10 provided in the upper portion of the pulling chamber 2 while adjusting the flow rate with a valve 24, and between the single crystal 3 being pulled and the gas rectifying cylinder 11. Can be passed between the heat shield member 12 and the melt surface of the raw material melt 4 and discharged from the gas outlet 9. Further, the gas outlet 9 is connected to a vacuum pump (not shown), and the pressure in the main chamber 1 and the pulling chamber 2 can be adjusted by adjusting the valve 26.
[0033]
Further, a magnetic field generator 25 made of a superconducting magnet capable of applying a magnetic field to the raw material melt 4 with a desired magnetic field strength is installed outside the main chamber 1, and the position of the magnetic field generator 25 is moved up and down. The magnetic field generator drive means 27 is provided so that it can be adjusted.
[0034]
The pulling mechanism 17, the crucible drive mechanism 21, the heater drive means 22, the heat shield member drive means 23, the valves 24 and 26, the magnetic field generator 25, and the magnetic field generator drive means 27 are respectively connected to the pull condition control means 18. For example, the position of the raw material melt surface measured by the CCD camera 19 and the diameter of the single crystal 3, the position of the heat shield member 12, the rotational speed of the single crystal 3, and the crucible 5 are connected to the pulling condition control means 18. , 6 position and rotation speed, flow rate of inert gas, position of the heater 7, magnetic field strength and magnetic field center of the magnetic field applied to the raw material melt 4 from the magnetic field generator 25, pressure gauge provided in the chamber By feeding back information such as the pressure in the chamber (not shown) and the pulling length of the single crystal obtained from the pulling mechanism 17, the pulling mechanism 17, The pulling condition control means 18 adjusts the body drive mechanism 21, heater drive means 22, heat shield member drive means 23, valves 24 and 26, magnetic field generator 25, and magnetic field generator drive means 27, respectively, and pulls up the single crystal. The distance L1 between the raw material melt surface and the heat shield member, the rotation speed of the single crystal, the rotation speed of the crucible, the flow rate of the inert gas, the position of the heater, the pressure in the chamber, the magnetic field strength, the raw material melt surface and the magnetic field The relative distance L3 from the center can be controlled and changed with high accuracy.
[0035]
The single crystal pulling apparatus that can be used in the present invention is not limited to the above-described apparatus, and a cooling jacket for cooling the single crystal 3 can be installed instead of the gas rectifying cylinder 11. Further, it is possible to provide an endothermic fin at the tip of the cooling jacket.
[0036]
In the case of growing, for example, a silicon single crystal by the CZ method using such a single crystal pulling apparatus 20, while introducing an inert gas (for example, argon gas) from the gas inlet 10 to the pulling chamber 2 and the main chamber 1. The seed crystal 16 fixed to the seed holder 15 is immersed in the raw material melt 4 in the quartz crucible 5 and then gently pulled up while rotating to form a seed squeeze, and then the crystal diameter is a predetermined value, for example, 200 mm or more. The silicon single crystal 3 having a substantially cylindrical straight body portion can be grown until the diameter is increased.
[0037]
In the present invention, when the straight body portion of the silicon single crystal 3 is grown in this way, the single crystal 3 is formed while controlling and changing the pulling speed V so that the diameter of the straight body portion of the single crystal becomes a predetermined value. The distance L1 between the raw material melt surface and the heat shield member, the rotation speed of the single crystal 3, the rotation speed of the crucibles 5 and 6, and the flow rate of the inert gas introduced into the chamber according to the fluctuation of the pulling speed V By changing at least one single crystal pulling condition among the position of the heater 7, the pressure in the chamber, the magnetic field strength, and the relative distance L3 between the raw material melt surface and the magnetic field center, the pulling axis near the solid-liquid interface is changed. The crystal temperature gradient G in the direction can be controlled. And thereby, the diameter control of the single crystal to be grown can be performed with high accuracy and the V / G control can be performed very stably, so that a high quality having a predetermined crystal diameter and a desired defect region can be obtained. This single crystal can be easily and stably grown.
[0038]
More specifically, for example, when a silicon single crystal is grown so that the defect region is an N region over the entire surface in the radial direction, after the seed restriction is formed as described above, the diameter is expanded until the diameter reaches a predetermined value. After the diameter, the pulling speed V is adjusted according to the manufacturing environment (for example, HZ of the single crystal pulling apparatus) in which the single crystal is manufactured so that the straight body portion of the single crystal can be grown in the N region.
[0039]
Then, when growing the diameter of the single crystal straight body portion, the pulling speed V is controlled and changed so that the diameter of the single crystal straight body portion is maintained at a predetermined value, and according to the fluctuation of the pulling speed V. The distance L1 between the raw material melt surface and the heat shield member, the rotation speed of the single crystal, the rotation speed of the crucible, the flow rate of the inert gas introduced into the chamber, the position of the heater, the pressure in the chamber, the magnetic field strength, the raw material melting The crystal temperature gradient G is controlled by changing at least one single crystal pulling condition of the relative distance L3 between the liquid level and the magnetic field center. At this time, other factors that can change the crystal temperature gradient G may be simultaneously controlled and changed.
[0040]
For example, when the pulling speed is increased in order to maintain the diameter of the straight body portion at a predetermined value, in order to increase the crystal temperature gradient G according to the increase of the pulling speed V, between the raw material melt surface and the heat shield member The distance L1 is decreased, the rotation speed of the single crystal is increased by the pulling mechanism 17, the rotation speed of the crucibles 5 and 6 is decreased by the crucible drive mechanism 21, and the flow rate of the inert gas introduced into the chamber by opening the valve 24 is increased. The valve 26 is adjusted by changing the position of the heater 7 by the heater driving means 22 (lowering the heater position) so that the relative distance L2 between the heat generation center position of the heater 7 and the raw material melt surface is increased. To reduce the pressure in the chamber, increase the magnetic field strength of the magnetic field applied to the raw material melt by the magnetic field generator 25, and the magnetic field of the magnetic field applied to the raw material melt surface and the raw material melt. At least one of the change in the single crystal pulling conditions such reducing the relative distance L3 between heart performed.
[0041]
Note that the distance L1 between the raw material melt surface and the heat shield member is set so that the quartz crucible 5 and the graphite crucible 6 are pushed up by the crucible drive mechanism 21 at a speed different from the melt surface decrease due to crystal growth. Easy and high accuracy by raising and lowering the height in the crystal growth axis direction, and moving the gas rectifying cylinder 11 up and down by the heat shield member driving means 23 to move the position of the heat shield member 12 up and down. Can be changed. The relative distance L3 between the raw material melt surface and the magnetic field center of the magnetic field applied to the raw material melt increases or decreases the height of the raw material melt surface in the crystal growth axis direction as described above, and generates a magnetic field. By moving the position of the magnetic field generator 25 up and down by the device driving means 27, it can be easily changed with high accuracy. Furthermore, in the above, the case where the heater heat generation center and the magnetic field center are below the position of the raw material melt surface is described as an example, but of course, the heater heat generation center and the magnetic field center are controlled to be above the melt surface. It is also possible to do.
[0042]
On the other hand, in the case where the pulling speed is slowed down in order to control the diameter of the straight body portion, the distance between the raw material melt surface and the heat shield member is reduced in order to reduce the crystal temperature gradient G according to the decrease in the pulling speed V. Increase L1, decrease single crystal rotation speed, increase crucible rotation speed, decrease flow rate of inert gas, decrease relative distance L2 between the center of heat generation of the heater and the raw material melt surface Of the single crystal pulling conditions such as raising the position of the heater 7, increasing the pressure in the chamber, decreasing the magnetic field strength, and increasing the relative distance L3 between the raw material melt surface and the magnetic field center Do at least one of the following:
[0043]
As described above, among the single crystal pulling conditions shown above, the distance L1 between the raw material melt surface and the heat shield member, the rotation speed of the single crystal, and the flow rate of the inert gas were changed. Sometimes the crystal temperature gradient G also changes quickly and shows a quick response. Also, the crucible rotation speed, the position of the heater, the pressure in the chamber, the magnetic field strength, the relative distance L3 between the raw material melt surface and the magnetic field center. Gradually changes the crystal temperature gradient G. Further, regarding the magnetic field strength and the relative distance L3 between the raw material melt surface and the magnetic field center, for example, the magnetic field strength is adjusted by the magnetic field generator 25, or the position of the magnetic field generator 25 is changed by the magnetic field generator driving means 27. When adjusting up and down, some time may be required until the magnetic field strength and magnetic field center of the magnetic field actually applied to the raw material melt change as desired.
[0044]
Therefore, in consideration of the characteristics of each single crystal pulling condition as described above, for example, the distance L1 between the raw material melt surface having excellent G response and the heat shielding member, the rotation speed of the single crystal, the flow rate of the inert gas Is preferably changed with respect to the fluctuation of the pulling speed V in a relatively short cycle. Based on this, by changing the distance L1 between the raw material melt surface and the heat shield member, the single crystal rotation speed, and the flow rate of the inert gas, the V / G can be controlled with high accuracy.
[0045]
Further, the rotational speed of the crucible for gradually changing G, the position of the heater, and the pressure in the chamber are preferably changed in response to fluctuations in the pulling speed from a short cycle to a long cycle, for example, several minutes to several tens of minutes The crystal temperature gradient G may be controlled by changing the pulling conditions based on the fluctuations in the average value of the pulling rates obtained over a relatively long period of time. Further, if the magnetic field strength and the relative distance L3 between the raw material melt surface and the magnetic field center are changed, the change in G is gentle and the magnetic field strength and the magnetic field center actually applied to the raw material melt change. Since it takes time to do so, an average value of the pulling speed is obtained in a very long time, for example, 5 minutes or more, and based on the fluctuation of the average value of the pulling speed, that is, the fluctuation of the pulling speed V in a long cycle. It is preferable to change the magnetic field strength and the relative distance L3 between the raw material melt surface and the magnetic field center. By calculating the average value of the pulling speed at different time intervals depending on the single crystal pulling condition thus changed, and changing each single crystal pulling condition based on the fluctuation of the average value of the pulling speed thus determined, It becomes possible to control the crystal temperature gradient G with high accuracy in accordance with fluctuations in the pulling speed, thereby controlling the V / G with very high accuracy and stably growing a single crystal in a desired defect region. be able to.
[0046]
Furthermore, in the present invention, when growing a single crystal, the crystal temperature gradient G is controlled by changing two or more of the single crystal pulling conditions shown above according to the fluctuation of the pulling speed V. Can also be done. Normally, each of the above single crystal pulling conditions also affects various other manufacturing conditions such as crystal quality when growing a single crystal. Therefore, depending on the manufacturing environment of the single crystal, there may be a concern that various inconveniences may occur if only one pulling condition is changed greatly. For example, if the distance L1 between the raw material melt surface and the heat shield member is excessively widened, or if the flow rate of the inert gas is excessively increased, the operability during single crystal growth may be deteriorated. If the rotational speed of the crucible and the rotational speed of the crucible become too fast or too slow, the shape of the single crystal straight body will be deformed, the quality distribution in the crystal plane will be deteriorated and the yield will be reduced. It is possible that inconvenience may occur.
[0047]
However, when growing a single crystal as described above, the crystal temperature gradient G can be increased over a wider range than when one pulling condition is changed by changing two or more of the single crystal pulling conditions. In addition, the control accuracy and responsiveness of the crystal temperature gradient G can be improved by changing the pulling conditions. Further, for example, when the crystal temperature gradient G is increased, the distance L1 between the raw material melt surface and the heat shielding member is reduced, while when the crystal temperature gradient G is decreased, the flow rate of the inert gas is decreased. By doing so, it becomes possible to control the crystal temperature gradient G without deteriorating the operability and reducing the influence on various other manufacturing conditions. Furthermore, for example, the single crystal pulling condition to be changed with respect to the fluctuation of the pulling speed with a relatively short cycle such as the distance L1 between the raw material melt surface and the heat shield member, If the single crystal pulling condition is changed in combination with the single crystal pulling condition that is changed with respect to the long-period pulling speed fluctuation, the crystal temperature gradient G can be controlled with higher accuracy with respect to various pulling speed V fluctuations. Thus, a single crystal having a desired defect region can be manufactured very stably.
[0048]
In the present invention, the distance L1 between the raw material melt surface and the heat shield member during single crystal growth, the rotation speed of the single crystal, the rotation speed of the crucible, the flow rate of the inert gas, the position of the heater, the pressure in the chamber It is sufficient to change at least one of the magnetic field strength, the relative distance L3 between the raw material melt surface and the magnetic field center, and depending on the manufacturing environment (for example, the structure of HZ) where the single crystal is actually manufactured, etc. The number and parameters of pulling conditions to be changed can be selected as appropriate. It is also possible to control and change factors other than the above simultaneously.
[0049]
Further, the control range of each pulling condition when changing the pulling condition can be appropriately determined according to the production environment of the single crystal and is not particularly limited. If one pulling condition is changed too much, there is a risk that the above-mentioned disadvantages occur. Therefore, during the single crystal pulling, it is preferable to change each single crystal pulling condition within a range in which the single crystal can be stably grown.
[0050]
For example, when changing the distance L1 between the raw material melt surface and the heat shield member during single crystal growth, depending on the diameter of the single crystal to be pulled up, the distance L1 is 1 to 500 mm, preferably 10 to 300 mm, Preferably, it is desirable to change in the range of 20 to 200 mm. Similarly, in the case of the rotational speed of the single crystal, it is changed in the range of 0.1 to 40 rpm, preferably 5 to 20 rpm, and in the case of the rotational speed of the crucible. Change in the range of 0.1 to 40 rpm, change in the range of 10 to 2000 L / min, preferably in the range of 60 to 300 L / min for the flow rate of the inert gas, and the position of the heater is the center of heat generation of the heater Heater position so that the relative distance L2 between the surface and the raw material melt surface varies in the range of 0 to 500 mm, preferably 10 to 200 mm, more preferably 30 to 100 mm. The pressure in the chamber is changed in the range of 5 to 300 mbar, preferably 10 to 200 mbar, the magnetic field strength is changed in the range of 100 to 10000 G, preferably 500 to 6000 G, and the raw material melt surface and the magnetic field are changed. In the case of the relative distance L3 from the center, it is desirable to change within a range of 0 to 1000 mm, preferably 5 to 500 mm.
[0051]
Furthermore, in the present invention, by using the pulling condition control means 18 shown in FIG. 9, the pulling speed V is automatically controlled and changed so that the diameter of the single crystal becomes a predetermined value during pulling of the single crystal. The crystal temperature gradient G can be automatically controlled according to the fluctuation of the pulling speed V. Specifically, for example, during the pulling of the single crystal, the position of the raw material melt surface measured by the CCD camera 19 and the diameter of the single crystal 3, the position of the heat shield member 12, the rotational speed of the single crystal 3, the crucible 5, 6 position and rotation speed, flow rate of inert gas, position of the heater 7, magnetic field strength and magnetic field center of the magnetic field applied to the raw material melt 4 from the magnetic field generator 25, pressure in the chamber, and the pulling mechanism 17. Is fed back to the pulling condition control means 18 so that the pulling condition control means 18 adjusts the driving of the pulling mechanism 17 so that the single crystal 3 can be grown with a predetermined diameter. The pulling speed V is automatically controlled and changed. The pulling speed V is controlled and changed in this way, and at the same time, the pulling condition control means 18 controls the pulling mechanism 17, the crucible driving mechanism 21, the heater driving means 22, and the heat shield member driving means according to the change in the changed pulling speed V. 23, the valves 24 and 26, the magnetic field generator 25, and the magnetic field generator driving means 27 are adjusted so that the distance L1 between the raw material melt surface and the heat shield member, the rotational speed of the single crystal, the rotational speed of the crucible, If at least one of the flow rate of the inert gas to be introduced, the position of the heater, the pressure in the chamber, the magnetic field strength, and the relative distance L3 between the raw material melt surface and the magnetic field center is changed, the crystal temperature gradient G The V / G can be controlled with high accuracy so that a single crystal having a desired defect region can be grown.
[0052]
As described above, according to the present invention, during the pulling of the single crystal, the pulling speed V is controlled and changed so that the diameter of the single crystal straight body portion becomes a predetermined value, and the raw material melt is changed according to the fluctuation of the pulling speed V. The distance L1 between the liquid surface and the heat shield member, the rotation speed of the single crystal, the rotation speed of the crucible, the flow rate of the inert gas introduced into the chamber, the position of the heater, the pressure in the chamber, the magnetic field strength, and the raw material melt surface By changing at least one of the relative distances L3 from the magnetic field center and controlling the crystal temperature gradient G, V / G can be stably controlled so that a single crystal having a desired defect region can be grown. Can do. Therefore, the single crystal diameter control and V / G control can be stably performed during the single crystal pulling without performing the temperature pattern adjustment for each single crystal pulling apparatus or each manufacturing batch as in the prior art. For example, even a large-diameter single crystal having a diameter of 200 mm or more has a predetermined crystal diameter over the entire straight body portion of the single crystal and has a very high defect area. Quality single crystals can be manufactured much more easily and with a higher yield.
[0053]
Furthermore, when the single crystal is grown, the controllability of V / G can be improved by controlling the crystal temperature gradient G according to the fluctuation of the pulling rate V as in the present invention. Therefore, for example, as shown in FIG. 10, it is possible to manufacture a single crystal by controlling V / G with high precision in a narrow region such as an Nv region or an Ni region in an N region that does not include a Cu deposit defect region, A high-quality single crystal having a desired defect region can be obtained very stably.
[0054]
In the present invention, it is also possible to install a cooling jacket for cooling the single crystal 3 instead of the gas rectifying cylinder 11 as described above, or to provide an endothermic fin at the tip of the cooling jacket. By changing the distance between the raw material melt surface and the cooling jacket and the distance between the raw material melt surface and the endothermic fin in accordance with the fluctuation of the pulling speed V, the single crystal having a desired defect region can be obtained. It is also possible to control so that it can be grown.
[0055]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to these.
(Example 1: Change of the distance L1 between a raw material melt surface and a heat shield member)
Using a single crystal pulling apparatus 20 shown in FIG. 9, 150 kg of raw material polycrystalline silicon is charged into a quartz crucible having a diameter of 24 inches (600 mm) by the CZ method, and an argon gas is allowed to flow from the gas inlet 10 while orientation <100 > A silicon single crystal having a diameter of 200 mm and an oxygen concentration of 22 to 23 ppma (ASTM'79) was grown in an N region where no Cu deposition defect was detected (the length of the single crystal straight body portion was about 100 cm).
[0056]
While the straight body portion of the silicon single crystal is grown, the diameter of the single crystal body portion is measured by the CCD camera 19 and the information is fed back to the pulling condition control means 18 to adjust the pulling mechanism 17. Thus, the pulling speed V was controlled and changed so that the diameter of the straight body portion of the silicon single crystal was 200 mm. At the same time, in order to change the distance L1 between the raw material melt surface and the heat shield member in accordance with the fluctuation of the pulling speed V, an average value of the pulling speeds for 2 minutes is obtained, and the average value of the pulling speeds is set to 0. If the distance L1 between the raw material melt surface and the heat shield member is reduced by 5 mm when it is increased by 02 mm / min, the distance L1 is 5 mm when the average pulling speed is decreased by 0.02 mm / min. The crucible drive mechanism 21 and the heat shield member drive means 23 were adjusted by the pulling condition control means 18 at such a rate as to increase.
[0057]
FIGS. 11A and 11B show the pulling rate V and the rate of change in the distance L1 between the raw material melt surface and the heat shield member, respectively, changed during the single crystal growth. As shown in FIG. 11 (a), the reason why the pulling speed is high within a range of 10 cm or less in the straight body portion is that the shoulder portion is pulled up from the enlarged diameter portion to enter the straight body portion. By forming the shoulder portion, it is possible to shift to pulling up the straight body portion and to stably control the diameter of the straight body portion.
[0058]
Next, after cutting out the wafer for inspection from each part in the growth axis direction of the single crystal grown as described above, surface grinding and polishing are performed to prepare a sample for inspection, and the crystal as shown below Quality characteristics were inspected.
[0059]
(1) Inspection of FPD (V region) and LSEPD (I region)
After inspecting the sample for inspection for 30 minutes without stirring, the inside of the wafer surface was observed with a microscope to confirm the presence or absence of crystal defects.
(2) Inspection of OSF
The sample for inspection was heat-treated at 1100 ° C. for 100 minutes in a wet oxygen atmosphere, and then the presence of OSF was confirmed by observing the wafer surface with a microscope.
(3) Inspection of defects by Cu deposition process
After forming an oxide film on the surface of the sample for inspection, Cu deposition treatment was performed to confirm the presence or absence of oxide film defects. The evaluation conditions at that time are as follows.
Oxide film: 25nm
Electrolytic strength: 6MV / cm
Voltage application time: 5 minutes
[0060]
(Comparative example)
150 kg of raw material polycrystalline silicon is charged into a quartz crucible having a diameter of 24 inches (600 mm) using the same single crystal pulling apparatus 20 as in the above example, and an orientation <100>, a diameter of 200 mm, and an oxygen concentration of 22 are obtained by CZ method. A silicon single crystal of ˜23 ppma (ASTM'79) was grown in the N region where no Cu deposition defect was detected (the length of the single crystal straight body was about 100 cm).
[0061]
Further, while the straight body portion of the silicon single crystal is grown, the diameter of the single crystal straight body portion is measured by the CCD camera 19 and the pulling condition control means 18 adjusts the pulling mechanism 17, whereby the silicon single crystal is crystallized. The pulling speed V was controlled / changed so that the diameter of the straight body portion was 200 mm. Note that the rate of change of the pulling speed V at this time was substantially the same as that in Example 1. On the other hand, the other single crystal pulling conditions were always constant during the pulling of the single crystal straight body.
[0062]
The rate of change in pulling speed V in this comparative example is shown in FIG. 11 (a) (substantially the same value as pulling speed V in Example 1). FIG. 11B shows the value of the distance L1 between the raw material melt surface during the body growth and the heat shield member (constant during single crystal growth).
And after cutting out the wafer for inspection from each part of the growth axis direction of the single crystal obtained above, surface grinding and polishing are performed to produce a sample for inspection, and the same crystal quality characteristics as in Example 1 Inspection was conducted.
[0063]
As a result of examining the crystal quality characteristics of each of the silicon single crystals produced in Example 1 and the comparative example as described above, the silicon single crystal produced in Example 1 was changed from a single crystal straight body part 10 cm to a straight body part. In the region up to the end, any defect of FPD, LSEPD, and OSF was not detected, and no defect due to Cu deposition treatment was observed. Therefore, it was confirmed that the silicon single crystal of Example 1 was an N region in which no Cu deposition defect was detected in all regions except the range of the straight body portion within 10 cm of the single crystal straight body portion.
[0064]
On the other hand, in the silicon single crystal produced in the comparative example, OSF is observed in the region of 40 to 55 cm of the straight body portion where the pulling speed V greatly fluctuates, and in the region of 65 to 75 cm of the straight body portion, LSEPD (I Area) was observed. Here, in order to make it easy to compare the results of the inspection of the crystal quality characteristics of the silicon single crystals produced in Example 1 and the comparative example, a diagram schematically showing the defect region of each single crystal is shown in FIG. Shown in (c).
[0065]
(Example 2: Change of rotation speed of single crystal, Example 3: Change of flow rate of inert gas)
Using the single crystal pulling apparatus 20 shown in FIG. 9, a silicon single crystal having an orientation <100>, a diameter of 200 mm, and an oxygen concentration of 22 to 23 ppma (ASTM'79) by the CZ method in the same manner as in Example 1 above. Was grown in the N region where no Cu deposition defect was detected (the length of the single crystal straight body was about 100 cm).
[0066]
In addition, while the straight body portion of the silicon single crystal is grown, in Example 2, the pulling speed V is controlled and changed so that the diameter of the straight body portion of the silicon single crystal becomes 200 mm as in Example 1 above. In order to change the rotation speed of the single crystal according to the fluctuation of the pulling speed V, the average value of the pulling speeds for 2 minutes is obtained, and the average value of the pulling speeds is increased by 0.02 mm / min. Is a rate at which the rotation speed of the single crystal is increased by 3.0 rpm, and when the average value of the pulling rate is decreased by 0.02 mm / min, the rotation speed of the single crystal is increased by a rate of 3.0 rpm. The pulling mechanism 17 was adjusted by the condition control means 18.
[0067]
Further, in Example 3, the pulling speed V is controlled and changed so that the diameter of the straight body of the silicon single crystal is 200 mm, and the flow rate of the inert gas (argon gas) according to the fluctuation of the pulling speed V. Therefore, when the average value of the pulling rate for 2 minutes is increased by 0.02 mm / min, the flow rate of argon gas is increased by 50 L / min, and the average value of the pulling rate is 0.02 mm. The valve 24 was adjusted by the pulling condition control means 18 at such a rate that the flow rate of argon gas decreased by 50 L / min when the flow rate decreased by 50 min / min.
[0068]
Here, the rate of change in pulling speed V and single crystal rotation speed changed during single crystal growth as described above in Example 2 is shown in FIGS. 12 (a) and 12 (b), respectively. The rate of change in pulling speed V and the flow rate of argon gas changed during single crystal growth in Example 3 are shown in FIGS. 13 (a) and 13 (b), respectively.
[0069]
And after cutting out the wafer for inspection from each part of the growth axis direction of the single crystal obtained in each of the above Example 2 and Example 3, surface grinding and polishing are performed to produce a sample for inspection, The same crystal quality characteristics were tested as in Example 1. As a result, both the silicon single crystals produced in Example 2 and Example 3 are N regions in which no Cu deposition defects are detected in all regions except the range of the straight body portion of the single crystal straight body portion within 10 cm. It was confirmed that
[0070]
(Example 4: Change of crucible rotation speed, Example 5: Change of pressure in the chamber)
Using the single crystal pulling apparatus 20 shown in FIG. 9, a silicon single crystal having an orientation <100>, a diameter of 200 mm, and an oxygen concentration of 22 to 23 ppma (ASTM'79) by the CZ method in the same manner as in Example 1 above. Was grown in the N region where no Cu deposition defect was detected (the length of the single crystal straight body was about 100 cm).
[0071]
Further, while the straight body portion of the silicon single crystal is grown, in Example 4, the pulling speed V is controlled and changed so that the diameter of the straight body portion of the silicon single crystal becomes 200 mm as in Example 1 above. In order to change the rotation speed of the crucible according to the fluctuation of the pulling speed V, the average value of the pulling speed for 10 minutes is obtained, and when the average value of the pulling speed is increased by 0.01 mm / min Pulling condition control means at such a rate that the rotational speed of the crucible is reduced by 0.5 rpm, and when the average value of the pulling speed is reduced by 0.01 mm / min, the rotational speed of the crucible is increased by 0.5 rpm. 18, the crucible drive mechanism 21 was adjusted.
[0072]
Furthermore, in Example 5, the pulling speed V is controlled and changed so that the diameter of the straight body of the silicon single crystal is 200 mm, and the pressure in the chamber is changed according to the fluctuation of the pulling speed V. When the average pulling speed for 10 minutes is increased by 0.01 mm / min, the pressure in the chamber is reduced by 25 mbar, and when the average pulling speed is decreased by 0.01 mm / min. The valve 26 was adjusted by the pulling condition control means 18 at such a rate that the pressure in the chamber increased by 25 mbar.
[0073]
Here, the rate of change in pulling speed V and crucible rotation speed changed during single crystal growth in Example 4 is shown in FIGS. 14A and 14B, respectively. FIG. 15A and FIG. 15B show the pulling speed V and the rate of change in the pressure in the chamber, respectively, changed during single crystal growth in FIG.
[0074]
And after cutting out the wafer for inspection from each part of the growth axis direction of the single crystal obtained in each of Example 4 and Example 5 above, surface grinding and polishing are performed to produce a sample for inspection, The same crystal quality characteristics were tested as in Example 1. As a result, in both the silicon single crystals produced in Example 4 and Example 5, although crystal defects were observed in some very small crystal parts, the range of the straight body portion of the single crystal straight body portion within 10 cm. It was found that the N region in which no Cu deposition defect was detected was in the region of 95% or more excluding. Therefore, in the silicon single crystals of Example 4 and Example 5, the set temperature pattern of the raw material melt is changed for each of the above comparative examples and for each single crystal pulling apparatus or single crystal production batch. Even when compared with a method of producing a single crystal with a predetermined crystal diameter, it was confirmed that a yield equal to or higher than that could be secured.
[0075]
Incidentally, the reason why crystal defects were observed in a part of the silicon single crystals of Example 4 and Example 5 was that even if the rotational speed of the crucible or the pressure in the chamber was changed according to the fluctuation of the pulling speed, it was actually This is probably because some time lag occurred before the crystal temperature gradient G changed.
[0076]
(Example 6: Change in the distance L1 between the raw material melt surface and the heat shielding member and the flow rate of the inert gas) Using the single crystal pulling apparatus 20 shown in FIG. Thus, a silicon single crystal having an orientation <100>, a diameter of 200 mm, and an oxygen concentration of 22 to 23 ppma (ASTM'79) was grown in an N region where no Cu deposition defect was detected (the length of the single crystal straight body portion was about 100 cm).
[0077]
Further, while the straight body portion of the silicon single crystal is grown, the pulling speed V is controlled and changed so that the diameter of the straight body portion of the silicon single crystal becomes 200 mm as in the first embodiment. The average value of the pulling speed per minute is obtained, and when the average value of the pulling speed is increased by 0.02 mm / min, the pulling condition is such that the distance L1 between the raw material melt surface and the heat shield member is reduced by 5 mm. When the crucible drive mechanism 21 is adjusted by the control means 18 and the average value of the pulling speed is reduced by 0.02 mm / min, the pulling condition control means 18 controls the valve at a rate such that the flow rate of argon gas is reduced by 50 L / min. 24 was adjusted.
[0078]
Then, after inspecting a wafer for inspection from each part in the growth axis direction of the obtained single crystal, surface grinding and polishing are performed to produce a sample for inspection, and the inspection of crystal quality characteristics similar to that in Example 1 is performed. Went. As a result, it was confirmed that the silicon single crystal produced in Example 6 was an N region in which no Cu deposition defect was detected in all regions except the range of the straight body portion within 10 cm of the single crystal straight body portion. did it.
[0079]
(Example 7)
The single crystal pulling apparatus 20 shown in FIG. 9 is different from the single crystal pulling apparatus in the shape and material of the heat shield member, and the orientation <100>, the diameter 200 mm, and the oxygen concentration is 22 to 23 ppma (by CZ method). A single crystal of ASTM '79) was continuously grown in batches in the N region where no Cu deposition defect was detected (the length of the single crystal straight body portion was about 100 cm).
[0080]
In addition, when a plurality of batches of silicon single crystals are continuously produced, when the single crystal straight body portion is grown in each production batch, the pulling speed V is set so that the diameter of the single crystals becomes 200 mm as in the case of Example 6. In addition, the distance L1 between the raw material melt surface and the heat shield member and the flow rate of the inert gas were changed according to the fluctuation of the pulling speed.
[0081]
Then, as a result of performing the inspection of the crystal quality characteristics similar to Example 1 on each single crystal for the plurality of single crystals obtained continuously, all the silicon single crystals are 10 cm in the straight body portion of the single crystal straight body portion. It was confirmed that in all the regions except for the inner range, the N region in which no Cu deposition defect was detected.
[0082]
(Example 8: Change of heater position)
Using the single crystal pulling apparatus 20 shown in FIG. 9, a silicon single crystal having an orientation <100>, a diameter of 200 mm, and an oxygen concentration of 22 to 23 ppma (ASTM'79) by the CZ method in the same manner as in Example 1 above. Was grown in the N region where no Cu deposition defect was detected (the length of the single crystal straight body was about 100 cm).
[0083]
Further, while the straight body portion of the silicon single crystal is being grown, in Example 8, the pulling speed V is controlled and changed so that the diameter of the straight body portion of the silicon single crystal becomes 200 mm as in Example 1 above. In order to change the position of the heater according to the fluctuation of the pulling speed V, the average value of the pulling speed for 10 minutes is obtained, and when the average value of the pulling speed is increased by 0.01 mm / min When the relative distance L2 between the heat generation center position of the heater and the raw material melt surface is increased by 15 mm, and when the average pulling rate is reduced by 0.01 mm / min, the heat generation center position of the heater and the raw material The heater driving means 22 was adjusted by the pulling condition control means 18 at a rate such that the relative distance L2 to the melt surface was reduced by 15 mm to change the position of the heater.
[0084]
Here, the pulling rate V changed during the single crystal growth as described above in Example 8 and the rate of change in the relative distance L2 between the heating center position of the heater and the raw material melt surface are shown in FIG. Shown in a) and (b).
[0085]
And after cutting out the wafer for an inspection from each site | part of the growth axis direction of the single crystal obtained in the said Example 8, surface grinding and grinding | polishing are performed and the sample for an inspection is produced, It is the same as that of Example 1. Crystal quality characteristics were inspected. As a result, the silicon single crystal produced in Example 8 had a crystal defect of 95% or more excluding the range of the straight body portion of the single crystal straight body portion within 10 cm, although crystal defects were observed in some extremely small crystal parts. It was found that the region was an N region where no Cu deposition defect was detected. Therefore, the silicon single crystal of Example 8 has a predetermined crystal diameter by changing the set temperature pattern of the raw material melt for each of the above comparative examples and the conventional single crystal pulling apparatus and each single crystal production batch. In comparison with the method for producing a single crystal, it was confirmed that a yield equal to or higher than that could be secured.
[0086]
The reason why crystal defects were observed in a part of the silicon single crystal of Example 8 was that the crystal temperature gradient G actually changed even if the position of the heater was changed according to the fluctuation of the pulling speed. This is thought to be due to some time lag.
[0087]
In addition, this invention is not limited to the said embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.
[0088]
For example, in the above embodiment, the case where a single crystal is grown in an N region is described as an example. However, the present invention is not limited to this, and a desired defect such as a V region, an I region, or an OSF region. Single crystals can also be grown in the region. Further, the present invention can be suitably used in the case of manufacturing a silicon single crystal, but is not limited to this, and can be similarly applied to the case of manufacturing a compound semiconductor single crystal or the like. Further, the present invention is similarly applied to a case where a single crystal is grown without applying a magnetic field to the raw material melt, or a case where a single crystal is grown while applying a magnetic field and a current to the raw material melt (EMCZ method). it can.
[0089]
In addition, the manufacturing method of the single crystal of the present invention is not necessarily limited to the case of carrying out with the entire length of the single crystal straight body, and the diameter is controlled at the pulling speed V over a part of the length, and the pulling speed V This includes the case where the crystal temperature gradient G is controlled in accordance with the fluctuation of the desired defect region. In particular, as described above, the region of 10 cm from the shoulder, which is the first half of the straight body, may not be stable in crystal quality. Therefore, it is preferable to carry out after 5 cm or 10 cm after the straight body, which tends to be in a steady state. .
[0090]
【The invention's effect】
As described above, according to the present invention, when a single crystal is grown, the crystal diameter can be stably controlled by controlling / changing the pulling speed V, and at the same time, the fluctuation of the pulling speed V is varied. By changing the single crystal pulling conditions according to the above and controlling the crystal temperature gradient G, V / G can be stably controlled so that a single crystal having a desired defect region can be grown. Then, by growing the single crystal while performing the diameter control and the V / G control in this manner, the single crystal has a predetermined crystal diameter over the entire straight body of the single crystal, and a desired defect region is formed. A high-quality single crystal can be easily manufactured with a high yield.
[Brief description of the drawings]
FIG. 1 is a graph showing an example of a relationship between a distance L1 between a raw material melt surface and a heat shield member and a crystal temperature gradient G;
FIG. 2 is a graph showing an example of the relationship between the rotation speed of a single crystal and the crystal temperature gradient G.
FIG. 3 is a graph showing an example of the relationship between the rotational speed of the crucible and the crystal temperature gradient G;
4 is a graph showing an example of a relationship between an inert gas flow rate and a crystal temperature gradient G. FIG.
FIG. 5 is a graph showing an example of the relationship between the relative distance L2 from the heating center position of the heater to the raw material melt surface and the crystal temperature gradient G;
6 is a graph showing an example of the relationship between the pressure in the chamber and the crystal temperature gradient G. FIG.
7 is a graph showing an example of the relationship between the magnetic field strength of the magnetic field applied to the raw material melt and the crystal temperature gradient G. FIG.
FIG. 8 is a graph showing an example of the relationship between the crystal temperature gradient G and the relative distance L3 between the raw material melt surface and the magnetic field center of the magnetic field applied to the raw material melt.
FIG. 9 is a schematic configuration diagram illustrating an example of a single crystal pulling apparatus that can be used in carrying out the method for producing a single crystal of the present invention.
FIG. 10 is an explanatory diagram showing the relationship between V / G and crystal defect distribution.
FIG. 11 (a) is a graph showing the relationship between the length in the growth axis direction of a single crystal straight body portion and the pulling speed when growing a single crystal in Example 1 and Comparative Example; These are the graphs which showed the relationship of the length of the growth axis direction of a single-crystal straight body part, and the distance L1 between a raw material melt surface and a thermal-insulation member, (c) produced in Example 1 and the comparative example. It is the figure which showed typically the defect area | region of the silicon single crystal.
12A is a graph showing the relationship between the length in the growth axis direction of the single crystal straight body portion in Example 2 and the pulling rate, and FIG. 12B is the growth axis of the single crystal straight body portion. It is the graph which showed the relationship between the length of a direction, and the rotational speed of a single crystal.
FIG. 13A is a graph showing the relationship between the length in the growth axis direction of the single crystal straight body part and the pulling rate in Example 3, and FIG. 13B is the growth axis of the single crystal straight body part. It is the graph which showed the relationship between the length of a direction, and the flow volume of argon gas.
14 (a) is a graph showing the relationship between the length in the growth axis direction of the single crystal straight body portion and the pulling rate in Example 4, and FIG. 14 (b) is the growth axis of the single crystal straight body portion. It is the graph which showed the relationship between the length of a direction, and the rotational speed of a crucible.
15 (a) is a graph showing the relationship between the length in the growth axis direction of the single crystal straight body portion and the pulling rate in Example 5, and FIG. 15 (b) is the growth axis of the single crystal straight body portion. It is the graph which showed the relationship between the length of a direction, and the pressure in a chamber.
16 (a) is a graph showing the relationship between the length in the growth axis direction of the single crystal straight body part and the pulling rate in Example 8, and FIG. 16 (b) is the growth axis of the single crystal straight body part. It is the graph which showed the relationship between the length of a direction, the heat generation center position of a heater, and the relative distance L2 between raw material melt surfaces.
[Explanation of symbols]
1 ... main chamber, 2 ... pulling chamber,
3 ... single crystal (silicon single crystal), 4 ... raw material melt, 5 ... quartz crucible,
6 ... Graphite crucible, 7 ... Heater, 8 ... Insulating material,
9 ... Gas outlet, 10 ... Gas inlet, 11 ... Gas rectifier,
12 ... Heat shield member, 13 ... Holding shaft, 14 ... Wire,
15 ... Seed holder, 16 ... Seed crystal, 17 ... Pulling mechanism,
18 ... Pulling condition control means, 19 ... CCD camera,
20 ... Single crystal pulling device, 21 ... Crucible drive mechanism,
22 ... heater driving means, 23 ... heat shield member driving means,
24, 26 ... valve, 25 ... magnetic field generator,
27: Magnetic field generator driving means.

Claims (4)

In a method of pulling a single crystal from a raw material melt in a chamber by the Czochralski method, when the single crystal is grown, a pulling speed when growing the straight body portion of the single crystal is V (mm / min), when the crystal temperature gradient in the pulling axis direction near the solid-liquid interface is represented by G (° C./mm), the pulling speed V is controlled so that the diameter of the straight body portion of the single crystal becomes a predetermined value. A heat shield member that pulls up the single crystal while changing the temperature, and that is arranged so that the crystal temperature gradient G is opposed to the melt surface of the raw material melt and the raw material melt surface in the chamber according to the fluctuation of the pulling speed V , The rotation speed of the single crystal when pulling up the single crystal, the rotation speed of the crucible containing the raw material melt, the flow rate of the inert gas introduced into the chamber, and the heater for heating the raw material melt Position, pressure in the chamber Controlled by changing at least one of the relative distance between the center of the magnetic field of the magnetic field applied magnetic field strength of the magnetic field to be applied to the raw material melt, and the raw material melt surface of the raw material melt, the pulling rate A method for producing a single crystal, wherein a ratio V / G (mm ² / ° C. · min) of V and a crystal temperature gradient G is controlled so that a single crystal having a desired defect region can be grown. 2. The method for producing a single crystal according to claim 1 , wherein the V / G is controlled so that a defect region of the single crystal to be grown becomes an N region over the entire radial direction. The diameter of the straight body part of the said single crystal shall be 200 mm or more, The manufacturing method of the single crystal of Claim 1 or Claim 2 characterized by the above-mentioned. The method for producing a single crystal according to any one of claims 1 to 3 , wherein the single crystal to be produced is a silicon single crystal.

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