JP2005187244A - Method for manufacturing single crystal and single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing single crystals, by which a plurality of single crystals, each having a respectively desired crystal quality, can be manufactured without changing structures in a chamber of a single crystal production apparatus when the plurality of single crystals are grown in the production of the single crystals by a CZ method. <P>SOLUTION: In the method for manufacturing at least two or more single crystals by pulling the single crystals from a raw material melt in a chamber by the CZ method, when at least two or more single crystals are grown, at least two or more single crystals, each having a respectively desired crystal quality, are manufactured by regulating the distance between the surface of the raw material melt and a heat shielding member arranged opposite to the surface of the raw material melt in the chamber to a value at which the quality of a relevant single crystal becomes within a target crystal standard, every time when the growth of each single crystal is started, then adjusting crystal temperature gradient G, and controlling the pulling speed V to a value at which the quality of a relevant single crystal becomes within a target crystal standard, depending on the growth of respective single crystals. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a single crystal by the Czochralski method (hereinafter abbreviated as CZ method), and in particular, a plurality of single crystals have a desired crystal quality for each single crystal. The present invention relates to a method for producing a single crystal that can be produced.

  As a single crystal used as a substrate of a semiconductor device, for example, there is a silicon single crystal or the like, which is mainly manufactured by the Czochralski 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.

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.

  Further, when the crystal pulling 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.

  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.

  Furthermore, it has been found that a part of the Nv region where oxygen precipitation is likely to occur after thermal oxidation treatment is a Cu deposition defect region in which defects detected by the Cu deposition treatment are remarkably generated. It has been found that it causes deterioration of electrical characteristics such as film withstand voltage characteristics.

In general, when a single crystal is manufactured by the CZ method, a single crystal is manufactured using a single crystal manufacturing apparatus 30 as shown in FIG. 8, for example.
The single crystal manufacturing apparatus 30 includes a member for containing and melting a raw material polycrystal such as silicon, a heat insulating material for cutting off heat, and the like. Contained. 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 (not shown) for pulling the single crystal 3 with a wire 14 is provided on the upper part. Yes.

  A quartz crucible 5 for containing the melted raw material melt 4 and a graphite crucible 6 for supporting the quartz crucible 5 are provided in the main chamber 1, and these crucibles 5 and 6 are rotated by a drive mechanism (not shown). It is supported by the holding shaft 13 so as to be movable up and down. The driving mechanism of the crucibles 5 and 6 raises the crucibles 5 and 6 by the amount corresponding to the liquid level drop in order to compensate for the liquid level drop of the raw material melt 4 accompanying the pulling of the single crystal 3.

  A cylindrical heater 7 is arranged so as to surround the crucibles 5 and 6. In order to prevent heat from the heater 7 from being directly radiated to the main chamber 1, a heat insulating material 8 is provided outside the heater 7 so as to surround the periphery thereof.

  A cylindrical gas rectifying cylinder 31 for controlling the cooling of the single crystal 3 is provided inside the main chamber 1, and an inverted conical heat shield member is provided at the lower end of the gas rectifying cylinder 31. 32 is installed. Further, a gas introduction port 10 is provided in the upper part of the pulling chamber 2, and an inert gas such as argon gas can be introduced from the gas introduction port 10. Between the single crystal 3 being pulled and the gas rectifying cylinder 31. Can be passed through the melt surface of the raw material melt 4 and discharged from the gas outlet 9.

  When a single crystal is grown by the CZ method using the single crystal manufacturing apparatus 30 described above, first, the raw material polycrystal is accommodated in the quartz crucible 5, and the polycrystalline raw material in the quartz crucible 5 is heated by the heater 7. And melt. Next, the seed crystal 16 fixed to the seed holder 15 is deposited on the raw material melt 4, and then pulled up gently while rotating, whereby the substantially cylindrical silicon single crystal 3 can be grown.

In the production of a single crystal by such a CZ method, the grown-in defects described above are between 1400 ° C. from the pulling rate V (mm / min) when the single crystal is grown and the melting point of silicon near the solid-liquid interface. The amount of introduction is considered to be determined by a parameter V / G (mm ² / ° C./min), which is the ratio of the crystal temperature gradient G (° C./mm) in the pulling axis direction (for example, non-patent literature) 1). Therefore, for example, the crystal pulling rate when growing a single crystal is changed, or the structure of a heater, a heat shield member, etc. constituting a hot zone in the main chamber of the single crystal manufacturing apparatus is changed. By changing the crystal temperature gradient G, it is possible to produce single crystals having various quality characteristics.

For example, in Patent Document 1, when a silicon single crystal is grown, the V / G value at the crystal center is controlled within a predetermined range (for example, 0.112 to 0.142 mm ² / ° C./min), and the single crystal It has been shown that a silicon single crystal wafer free from defects caused by voids and defects caused by dislocation loops can be obtained by pulling up.

  Furthermore, in Patent Document 2, the inner surface facing the single crystal of the heat shield coaxial with the pulling shaft placed around the single crystal to be grown is an inverted frustoconical surface whose inner diameter increases toward the upper side. Disclosed is a silicon single crystal manufacturing apparatus having a predetermined dimension and having a height H from the melt surface of the lower end portion of 50 to 130 mm. By using this apparatus, the pulling speed is appropriately selected. It is said that a single crystal with extremely few grow-in defects can be easily manufactured.

  However, as described above, when a single crystal having a desired crystal quality is manufactured, particularly when a single crystal is grown in a region including a V region where the pulling rate can be increased for reasons such as improvement in productivity. Control by two methods, that is, a method for controlling the defect occurrence region and a method for controlling the defect density in the defect occurrence region are required. Usually, the defect generation region can be controlled by the crystal pulling rate V and the crystal temperature gradient G near the solid-liquid interface as described above, and the defect density in the defect generation region is the temperature in the furnace in the single crystal manufacturing apparatus. It can be controlled by the thermal history determined by the distribution and the crystal pulling rate. The crystal temperature gradient in the vicinity of the solid-liquid interface and the temperature distribution in the furnace are determined by the structure in the furnace, and by controlling the crystal pulling speed as a manufacturing condition, a single crystal having a desired defect occurrence region and defect density can be obtained. can get.

  Therefore, for example, when manufacturing a plurality of single crystals, in order to make each single crystal have a different desired defect region and a desired defect density, the in-furnace structure required for each crystal quality is reduced. It is necessary to design and manufacture a single crystal.For example, changing the defect density without changing the defect generation area, or changing the defect generation area without changing the defect density is the in-furnace structure of the single crystal manufacturing apparatus. There was a problem that it could not be realized unless it was changed.

  Therefore, in the conventional single crystal manufacturing, every time a single crystal is grown, for example, a furnace structure suitable for each crystal quality is designed and manufactured according to the user's request, etc. Each in-furnace structure had to be prepared for quality and work such as replacement / replacement of the structure had to be performed. For this reason, as diversification in quality requirements for single crystals progresses, problems such as an increase in manufacturing cost and a decrease in productivity occur, and there is also a problem that the burden on the worker increases. Therefore, in the past, as a countermeasure, a technique of controlling the thermal history by changing the dimensions and installation position of the heater has been proposed, but this also increases the equipment cost and makes the structure of the internal structure of the furnace complicated. Therefore, the development of more effective technology is desired.

JP-A-11-147786 JP 2001-261493 A V. V. Voronkov, Journal of Crystal Growth, vol. 59 (1982), pp. 625 to 643

  Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to provide a single crystal manufacturing apparatus for growing a plurality of single crystals in the manufacture of a single crystal by the Czochralski method. An object of the present invention is to provide a method for producing a single crystal, which can produce a single crystal so that each single crystal has a desired crystal quality without replacing a structure (hot zone part) in a chamber.

  In order to achieve the above object, according to the present invention, in a method for producing at least two or more single crystals by pulling a single crystal from a raw material melt in a chamber by a Czochralski method, When the pulling speed when growing the body portion is represented by V (mm / min) and the crystal temperature gradient in the pulling axis direction near the solid-liquid interface is represented by G (° C./mm), the at least two single crystals are When growing, the distance between the melt surface of the raw material melt and the heat shielding member disposed opposite to the raw material melt surface in the chamber is increased each time the single crystal is started to grow. The crystal temperature gradient G is adjusted by adjusting the size to be a crystal standard of the crystal, and the pulling speed V is controlled to a value at which the single crystal becomes a target crystal standard according to the growth of each single crystal. The at least two or more Method for producing a single crystal, characterized in that the crystal to manufacture the desired so as to have a crystal quality single crystal for each single crystal is provided (claim 1).

  Thus, when manufacturing at least two or more single crystals by the CZ method, the distance between the raw material melt surface and the heat shielding member is adjusted to a predetermined size each time the growth of each single crystal is started. By adjusting the crystal temperature gradient G and controlling the pulling rate V to a predetermined value according to the growth of each single crystal, the single crystal is manufactured. A plurality of single crystals can be easily manufactured at low cost and high productivity so that each crystal has a desired crystal quality, and the burden on the operator can be greatly reduced.

At this time, the at least two single crystals can be manufactured so as to have different defect regions and / or different defect densities for each single crystal.
The method for producing a single crystal of the present invention has the above-described characteristics, so that when producing at least two or more single crystals, each single crystal has different defect regions and / or different defect densities. Thus, a plurality of single crystals can be manufactured very easily and at low cost.

In this case, it is preferable to grow the at least two single crystals from the same crucible.
In this way, by continuously growing at least two single crystals from the same crucible, for example, in one production batch, each single crystal has a desired crystal quality without changing the structure in the chamber. In this way, it is possible to manufacture a plurality of single crystals to produce a desired amount of crystals of a desired quality, which is sufficient for multi-product production, and shortens manufacturing time and further reduces costs in single crystal manufacturing. Can be planned.

In addition, when the single crystal is grown in the V region, defects formed in the single crystal can have a desired size.
In the present invention, particularly when a single crystal is grown in the V region, not only can a desired defect density be achieved, but also the size of defects formed in the single crystal can be set to a desired size. Thus, single crystals having various crystal qualities can be easily made and high-quality single crystals that reliably satisfy the user's requirements can be stably manufactured at low cost.

Furthermore, it is preferable that the distance between the raw material melt surface and the heat shield member is automatically adjusted according to a change condition obtained by conducting a test in advance.
When adjusting the distance between the raw material melt surface and the heat shield member for each growth of each single crystal, for example, a simulation analysis of the distribution of the crystal temperature gradient G in a manufacturing environment where the single crystal is actually manufactured, or Based on the information obtained from the actual production and other tests, the change conditions for changing the distance between the raw material melt surface and the heat shield member are determined so that each single crystal has the target crystal specification. Keep it. Then, the crystal temperature gradient G can be automatically adjusted with high accuracy by automatically adjusting the distance between the raw material melt surface and the heat shield member every time the growth of the single crystal is started according to the obtained change condition. Therefore, it is possible to more stably manufacture a plurality of single crystals in which each single crystal has a desired crystal quality with high accuracy.

In addition, it is preferable to control the distance between the raw material melt surface and the heat shield member during the pulling of the straight body portion of the single crystal.
In this way, by controlling the distance between the raw material melt surface and the heat shield member during the pulling of the single crystal straight body portion, the crystal temperature gradient G can be controlled with very high accuracy during single crystal growth. Therefore, a single crystal having a desired crystal quality can be manufactured very stably.

In the manufacturing method of the present invention, a cooling cylinder forcedly cooled with a cooling medium and a cooling auxiliary member installed below the cooling cylinder are arranged in the chamber so as to surround the single crystal to be grown. (Claim 7).
In this way, by placing the cooling cylinder and the cooling auxiliary member in the chamber so as to surround the single crystal, when the single crystal is pulled up, for example, a temperature zone where point defects are aggregated is cooled to a desired level. It becomes possible to rapidly cool at a speed, and a single crystal having a desired crystal quality with high accuracy can be grown more reliably.

Furthermore, it is preferable that the single crystal is pulled while applying a magnetic field having a central magnetic field strength in the range of 300 gauss to 6000 gauss (claim 8).
Thus, by applying a magnetic field having a central magnetic field strength of 300 to 6000 gauss when pulling up the single crystal, the convection of the raw material melt in the crucible is controlled, and the melt convection is stable. Since a single crystal can be grown in a state where the crystal growth interface shape is good, a high-quality single crystal having a desired crystal quality can be manufactured with higher production yield and higher productivity.

The single crystal to be manufactured can be a silicon single crystal (Claim 9), and the diameter of the straight body of the single crystal can be 150 mm or more (Claim 10).
The present invention can be particularly suitably used when a silicon single crystal is manufactured or when the diameter of the straight body portion is a large diameter of 150 mm or more. Thereby, a plurality of silicon single crystals each having a desired crystal quality can be manufactured easily and at low cost without replacing the structure in the chamber. In addition, even when manufacturing a plurality of large-diameter single crystals having a diameter of 150 mm or more, in which the temperature distribution in the crystal diameter direction plane is likely to be large, each single crystal has a desired crystal without changing the structure in the chamber. Manufacturing can be performed easily and at low cost so as to have quality.

And according to this invention, the single crystal manufactured by the manufacturing method of the said single crystal is provided (Claim 11).
Thus, the single crystal manufactured according to the present invention is a high-quality and low-cost single crystal manufactured so that each single crystal has a desired crystal quality without replacing the structure in the chamber. be able to.

  As described above, according to the present invention, when manufacturing at least two or more single crystals by the CZ method, each single crystal has a desired crystal quality without replacing the structure in the chamber. Thus, a plurality of single crystals can be easily manufactured at low cost and high productivity.

Hereinafter, although an embodiment is described about the present invention, the present invention is not limited to these.
When manufacturing at least two or more single crystals by the CZ method, the present inventors do not replace / replace the structure in the chamber as in the prior art, and each single crystal has a desired crystal quality. As a result, diligent experiments and studies were conducted on a production method capable of producing a single crystal so as to have the above. As a result, attention is paid to the distance between the melt surface of the raw material melt when the single crystal is grown and the heat shield member provided in the chamber, and the distance between the raw material melt surface and the heat shield member is determined for each individual unit. By adjusting each time crystal growth is started, the crystal temperature gradient G in the pulling axis direction between 1400 ° C. and the melting point of silicon in the vicinity of the solid-liquid interface can be adjusted, so that a plurality of single crystals each having a desired crystal quality can be obtained. It was considered that crystals could be manufactured without replacing the furnace structure.

  Here, comprehensive heat transfer analysis software FEMAG (F. Dupret, P. Nicodeme, Y. Ryckmans, P. Waterers, and M. J. Crochet, Int. J. Heat Mass Transfer, 33, 1849 (1990)) was used. Simulation analysis of the crystal temperature gradient G in the pulling axis direction when the single crystal is pulled by adjusting the distance between the melt surface of the raw material melt and the heat shielding member provided in the chamber to various sizes An example of the results is shown in FIG.

  As shown in FIG. 1, it can be seen from the results of the simulation analysis that the crystal temperature gradient G can be changed by changing the distance between the raw material melt surface and the heat shield member. Therefore, the inventors adjusted the distance between the raw material melt surface and the heat shielding member to various sizes when starting the growth of the single crystal based on the result of the simulation analysis described above, A single crystal was produced by controlling the pulling speed V when growing the straight body of the film to various values, and an experiment was conducted to examine the crystal quality of the single crystal obtained under each condition.

(Experiment)
Using the conventional single crystal manufacturing apparatus 30 shown in FIG. 8, 300 kg of raw polycrystalline silicon was charged into a quartz crucible 5 having a diameter of 32 inches (800 mm), and a silicon single crystal having a diameter of 300 mm was grown by the CZ method. At this time, the shortest distance between the melt surface of the raw material melt 4 and the heat shield member 32 is adjusted to be 30, 50, or 70 mm when starting the growth of the single crystal. Various silicon single crystals were manufactured by controlling the pulling speed V when growing the body part in a range of 0.9 to 0.3 mm / min. Then, after each wafer was cut out from the obtained straight body portions of various silicon single crystals, surface grinding and polishing were performed to prepare samples for inspection, and the distribution of defect areas on the sample wafer was measured with a foreign substance inspection device ( Inspected by SP-1), manufactured by KLA Tencor. The inspection result obtained by this defect area inspection is shown in FIG.

  As shown in FIG. 2, it can be seen that the defect region of the single crystal to be grown also changes by changing the distance between the raw material melt surface and the heat shielding member or by changing the pulling speed V. From this result, a combination of the magnitude of the distance between the raw material melt surface and the heat shield member that is adjusted when growing the single crystal and the value of the pulling speed V that is controlled during pulling of the single crystal straight body portion is appropriately selected. By doing so, it can be seen that a single crystal having a desired defect region can be easily manufactured without replacement / replacement of the structure in the chamber.

  Further, the present inventors have made a single crystal having the same defect region among the single crystals produced above, that is, a single crystal of A1, B1, and C1, and a single crystal of A2, B2, and C2 in FIG. The defect density and defect size distribution were investigated. The results are shown in FIGS.

  As shown in FIGS. 3 and 4, even if the single crystal of A1, B1, and C1 showing the same defect region, or the single crystal of A2, B2, and C2, the defect density of these single crystals is investigated. As can be seen, each has a different defect density (number of defects). Furthermore, as shown in FIG. 3 and FIG. 4, in the case of a single crystal grown in the V region, it can be confirmed that even if the single crystal has the same defect region, the distribution of the size of defects formed is different. . For example, when the single crystal A1 having the same defect region and the single crystal C1 are compared, the single crystal of C1 has a smaller number of defects having a size of 0.12 μm or more, but a defect of 0.11 μm or more is A1. Single crystal is less. That is, it can be seen that the single crystal C1 has a lower defect density than the single crystal A1, but has a larger size of each defect.

  This is because, by changing the distance between the raw material melt surface and the heat shield member, the optimum crystal pulling speed value selected for growing a single crystal in a desired defect region changes, and thereby, during crystal growth. This seems to be due to the change in the thermal history of the single crystal. That is, when the distance between the raw material melt surface and the heat shield member changes, the optimum crystal pulling rate also changes. As a result, as shown in FIG. The passage time of the single crystal in the (-1080 ° C. band) changes. For example, the slower the crystal pulling rate, the longer the transit time in the 1150-1080 ° band, so that the agglomeration of defects proceeds, so that small size defects are reduced However, defects of large size will increase.

  The present invention utilizes the fact that the defect region and defect density of the single crystal grown as described above can be changed by changing the distance between the raw material melt surface and the heat shield member and the pulling speed V. It has been found.

  That is, in the method for producing a single crystal of the present invention, at least two or more single crystals are grown in the method for producing at least two or more single crystals by pulling the single crystal from the raw material melt in the chamber by the CZ method. When the growth of individual single crystals is started, the distance between the raw material melt surface and the heat shielding member disposed opposite to the raw material melt surface in the chamber is such that the single crystal becomes the target crystal standard. The crystal temperature gradient G is adjusted by adjusting the thickness, and the pulling rate V is controlled to a value at which the single crystal becomes a target crystal standard according to the growth of each single crystal, whereby at least two or more single crystals are obtained. This is characterized in that the single crystal is manufactured so that the crystal has a desired crystal quality for each single crystal.

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 of the present invention includes a heat shield member disposed in the chamber so as to face the surface of the raw material melt, and starts the growth of the single crystal. Although it will not specifically limit if the distance between a surface and a heat-shielding member can be adjusted and changed, For example, a single crystal pulling apparatus as shown in FIG. 6 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.

  In the single crystal pulling apparatus 20 shown in FIG. 6, a quartz crucible 5 that accommodates a raw material melt 4 and a graphite crucible 6 that protects the quartz crucible 5 are rotated and moved up and down by a crucible drive mechanism 21 in a main chamber 1. A heater 7 and a heat insulating material 8 for heating the raw material melt are disposed so as to surround the crucibles 5, 6.

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.
Further, a cooling cylinder 22 is installed inside the main chamber 1 so as to surround the single crystal 3 being pulled, and the single crystal is circulated through the cooling cylinder 22 by flowing a cooling medium from the refrigerant inlet 23. 3 can be forcibly cooled. In this case, the amount of heat removed from the cooling cylinder 22 can be changed by adjusting the flow rate and temperature of the cooling medium flowing in the cooling cylinder 22. As a result, a desired cooling atmosphere can be created, and control can be performed so that a specific temperature zone is rapidly cooled at a desired cooling rate during pulling of the single crystal.

  Further, a cylindrical cooling auxiliary member 11 extending from the lower part of the cooling cylinder 22 to the vicinity of the surface of the raw material melt 4 is provided. This cooling auxiliary member 11 surrounds the periphery of the high-temperature single crystal 3 immediately after being pulled up, and has an effect of cooling the single crystal 3 by blocking radiant heat from the heater 7 or the raw material melt 4. The shape of the cooling auxiliary member is not limited to a cylindrical shape, and other examples include a shape whose diameter is reduced downward. By changing the arrangement position, shape, and the like of this cooling auxiliary member, it is possible to control each temperature zone to be rapidly cooled at a desired cooling rate when pulling the single crystal.

  Further, a protective member 24 is provided outside the cooling cylinder 22. The protection member 24 extends from the ceiling portion of the main chamber 1 and is disposed so as to cover the outer peripheral surface including the lower end surface of the cooling cylinder 22 in the main chamber 1. By providing the protective member 24 in this way, it is possible to prevent the raw material melt that may be scattered when the raw material polycrystal is melted from adhering to the cooling cylinder 22, and from the heater 7 and the like. Since it is possible to prevent the radiant heat from directly hitting the cooling cylinder 22, it is possible to prevent damage to the cooling cylinder 22 and improve the heat removal effect.

  A heat shield member 12 is installed below the cooling auxiliary member 11 so as to face the raw material melt 4 to cut off radiation from the surface of the raw material melt 4 and to keep the surface of the raw material melt 4 warm. Like to do. In the present invention, it is also possible to install a heat shield member driving means (not shown) that can move the cooling auxiliary member 11 up and down to adjust the position of the heat shield member 12 up and down. 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. Further, the heat shield member 12 only needs to be disposed so as to face the melt surface, and is not necessarily limited to the one installed below the cooling auxiliary member 11 as described above. For example, FIG. As shown in FIG. 7, an inverted conical heat shield member 12 a is installed at the lower end of the gas rectifying cylinder 26, and the tip of the holding member 27 installed in the heat insulating material 8 as shown in FIG. The heat shield member 12b can also be installed inclined.

  In addition, an inert gas such as argon gas can be introduced from the gas inlet 10 provided in the upper part of the pulling chamber 2, and is passed between the single crystal 3 being pulled, the cooling cylinder 22, and the cooling auxiliary member 11. Then, it can pass through between the heat shield member 12 and the melt surface of the raw material melt 4, and can be discharged from the gas outlet 9.

  Further, the crucible drive mechanism 21 and the heat shield member drive means (not shown) are connected to the drive control means 18, respectively. For example, information such as the position of the crucibles 5 and 6, the position of the heat shield member 12, the position of the melt surface of the raw material melt 4 measured by the CCD camera 19 is fed back to the drive control unit 18. The position of the crucibles 5 and 6 and / or the position of the heat shield member 12 can be changed by adjusting the crucible drive mechanism 21 and / or the heat shield member drive means with the drive control means 18. The distance L between the melt surface and the heat shield member 12 can be adjusted. In the present invention, the heat shield member driving means is not necessarily installed. For example, the distance between the raw material melt surface and the heat shield member may be adjusted by the crucible drive mechanism 21. The single crystal pulling apparatus has an advantage that it can be applied to a conventionally used apparatus without significant modification.

  In addition, the single crystal pulling apparatus 20 shown in FIG. 6 can arrange the magnetic field generator 25 outside the main chamber 1, and the magnetic field intensity of the raw material melt is, for example, 300 gauss or more and 6000 gauss or less. Can be applied.

  When, for example, a silicon single crystal is grown by the CZ method using such a single crystal pulling apparatus 20, the seed crystal 16 fixed to the seed holder 15 is used as the raw material melt (silicon melt) 4 in the quartz crucible 5. The silicon single crystal 3 having a substantially cylindrical straight body portion can be grown by immersing and then gently pulling up while rotating to form a seed drawing and then expanding to a desired diameter.

  In the present invention, when the silicon single crystal is pulled up from the raw material melt by the CZ method in this way to produce at least two single crystals, the distance L between the raw material melt surface and the heat shielding member is set to each individual silicon. Each time the growth of a single crystal is started, the crystal temperature gradient G is adjusted by adjusting the size of the single crystal to the target crystal standard, and the pulling speed V when growing the single crystal straight body portion is set to each individual crystal. According to the growth of the single crystal, the single crystal is controlled to a value that satisfies the target crystal standard.

  More specifically, when starting the pulling of the first silicon single crystal, the crucible driving mechanism 21 positions the crucibles 5 and 6 so that the first silicon single crystal becomes the target crystal standard. The crystal temperature gradient G is adjusted by adjusting the distance L between the raw material melt surface and the heat shield member by moving or by moving the position of the heat shield member 12 by the heat shield member driving means.

  Then, after adjusting the distance L between the raw material melt surface and the heat shield member as described above, the pulling of the single crystal is started, and when the straight body of the single crystal is grown, the silicon single crystal has the target crystal standard. The single crystal is grown while controlling the pulling speed V so that

  In this way, when the growth of the first silicon single crystal is started, the crystal temperature gradient G is adjusted by adjusting the distance L between the raw material melt surface and the heat shield member to a predetermined size, and the pulling speed V By growing the silicon single crystal while controlling the value to a predetermined value, the single crystal can be manufactured so that the first single crystal has a desired crystal quality.

  At this time, for example, a single crystal pulling apparatus used for manufacturing a single crystal is subjected to tests such as simulation analysis or actual measurement in advance, and a single crystal grown under conditions of the distance L between the raw material melt surface and the heat shield member and the pulling speed V By investigating the relationship with the crystal quality of the material and making it into data, the size of the distance L between the raw material melt surface and the heat shield member, and the straight body part so that the single crystal to be grown has the desired crystal quality The value of the pulling speed V when growing can be appropriately set.

  In particular, in this case, the relationship between the condition of the distance L between the raw material melt surface and the heat shield member and the pulling speed V examined in advance and the crystal quality of the single crystal to be grown, and the target crystal quality of the single crystal to be grown Is input to the drive control means 18 and when the growth of the single crystal is started, for example, the position of the crucibles 5 and 6, the position of the heat shield member 12, and the raw material melt 4 measured by the CCD camera 19. Information such as the position of the melt surface is fed back to the drive control means 18 so that the distance between the raw material melt surface and the heat shield member is automatically changed to a size in which the single crystal becomes the target crystal standard. Can do. Thus, by automatically adjusting the distance between the raw material melt surface and the heat shield member according to the change condition obtained by conducting a test in advance, the crystal temperature gradient G can be adjusted with high accuracy. A single crystal having a desired crystal quality with high accuracy can be manufactured very stably.

  Further, when the silicon single crystal is manufactured as described above, it is preferable to control the distance L between the raw material melt surface and the heat shield member while the straight body portion of the silicon single crystal is pulled up. In general, it is known that the crystal temperature gradient G tends to decrease as the growth of the single crystal proceeds, and becomes smaller at the end of growth than at the start of growth of the single crystal straight body. Therefore, during the pulling of the single crystal straight body portion, not only the pulling speed V is controlled as described above, but also the position of the crucibles 5 and 6 and the position of the heat shield member 12 by the crucible drive mechanism or the heat shield member drive means, for example. By adjusting the distance L between the raw material melt surface and the heat shield member, the crystal temperature gradient G can be controlled with a very high precision so as to have a constant value, for example. A single crystal having a desired crystal quality can be manufactured very stably.

  Further, as described above, the cooling cylinder 22 and the cooling auxiliary member 11 are disposed in the chamber of the single crystal pulling apparatus 20 so as to surround the silicon single crystal. By adjusting the flow rate and temperature, it becomes possible to rapidly cool a predetermined temperature zone during pulling of the single crystal, for example, a temperature zone where point defects are aggregated (approximately 1150 to 1080 ° C.) at a desired cooling rate. A single crystal having a desired crystal quality with high accuracy can be grown more reliably.

  Moreover, when pulling up the single crystal as described above, it is preferable to apply a magnetic field having a central magnetic field strength in the range of 300 gauss to 6000 gauss from the magnetic field generator 25. Thus, when pulling up the single crystal, by applying a magnetic field having a central magnetic field strength of 300 to 6000 gauss, the convection of the raw material melt in the quartz crucible is controlled, and the melt convection is stable. Thus, it is possible to grow a single crystal with a good crystal growth interface shape. Therefore, a high-quality single crystal can be produced with a higher production yield and higher productivity.

  In the present invention, after growing the first single crystal as described above, when starting the growth of the second single crystal, the raw material fusion is performed so that the second single crystal becomes the target crystal specification. The crystal temperature gradient G is adjusted by adjusting the distance L between the liquid surface and the heat shield member again. Thereafter, the pulling of the second single crystal is started, and when the straight body portion of the single crystal is grown, the pulling speed V is controlled so that the second single crystal becomes the target crystal standard, A single crystal is grown in the same manner as when a single crystal is grown. By growing the second single crystal in this manner, a single crystal having a desired crystal quality can be stably produced. In this case, in the present invention, even if the first and second crystal specifications are different, the distance L between the raw material melt surface and the heat shield member is adjusted without performing work such as replacing the in-furnace parts. As long as the crystal temperature gradient G is adjusted and then the straight body portion of the single crystal is grown, the pulling speed V is controlled so that the single crystal becomes the target crystal standard. The greatest advantage is that crystals can be grown.

  After that, for example, when the third and fourth single crystals are grown, as in the case of the first and second, the raw material is set so that the single crystal becomes the target crystal standard every time the growth of each single crystal is started. The crystal temperature gradient G is adjusted by adjusting the distance L between the melt surface and the heat shield member, and then when the straight body of the single crystal is grown, the pulling speed V is set so that the single crystal becomes the target crystal standard. By controlling the growth of the single crystal, the single crystal can be manufactured so that each single crystal has a desired crystal quality. Also in this case, the quality standards of the third and fourth crystals may be different from those of the first and second crystals.

  By producing at least two or more single crystals as described above, each single crystal has a desired crystal quality in one kind of hot zone without replacing the structure (hot zone part) in the chamber. Thus, a plurality of single crystals can be easily manufactured at low cost and high productivity. In addition, if a single crystal is manufactured in this way, it is not necessary to replace the structure in the chamber, so there is no need to purchase and store various structures as in the prior art, and a significant cost reduction can be achieved. It becomes possible. Furthermore, the plurality of single crystals produced in this way can be made into high-quality and very inexpensive single crystals in which each single crystal has a desired crystal quality.

  In particular, in the present invention, the defect region is controlled by the distance between the raw material melt surface and the heat shielding member, and the defect density is controlled independently such that the thermal history of the single crystal is controlled by the pulling rate. For example, depending on the purpose and requirement of each single crystal, the defect region is a region where the entire crystal surface is a V region, a region where an OSF ring is present, or the entire crystal surface is an N region. Different defects for each single crystal that have a predetermined defect density if the entire surface of the crystal is an I region, or if the single crystal includes a V region or an I region as a defect region. A plurality of single crystals can be produced with regions and / or different defect densities without replacing the structure in the chamber. Therefore, for example, it is easy to change the defect density without changing the defect occurrence area, which cannot be realized without replacing the structure in the chamber in the past, or to change the defect occurrence area without changing the defect density. Thus, a plurality of single crystals having different crystal qualities for each single crystal can be manufactured very easily and the burden on the operator can be greatly reduced.

  Furthermore, when the single crystal is grown in the V region by the manufacturing method of the present invention, as shown in the above experimental results, the defects formed in the single crystal can only have a desired defect density. In addition, the defect size can be set to a desired size. For this reason, single crystals having various crystal qualities can be easily made and high-quality single crystals that reliably satisfy the user's requirements can be stably manufactured at low cost.

  In the method for producing a single crystal according to the present invention, as is conventionally performed, single crystals are grown one by one using one quartz crucible in one production batch, and at least two or more single crystals are produced. Crystals can be produced in a plurality of production batches, and at least two single crystals can be continuously grown in one production batch from the same quartz crucible. In particular, two or more single crystals in the same crucible are repeatedly filled with raw materials and grown single crystals, or are continuously grown in one production batch while filling and replenishing raw materials. Single crystals can be manufactured so that each single crystal has a desired crystal quality without changing the structure. In this way, it is possible to shorten the manufacturing time and further reduce the cost.

  And the manufacturing method of such a single crystal of this invention is 150 mm or more in diameter of the silicon single crystal used as the material of the substrate for semiconductor devices, and the straight body part which demand is increasing in recent years, in particular, 200 mm or more, It can be particularly preferably used when producing a single crystal having a large diameter of 300 mm or more. Thereby, for example, a plurality of silicon single crystals each having a desired crystal quality can be manufactured easily and at low cost without replacing the structure in the chamber, and a large diameter having a diameter of 150 mm or more. Even when a plurality of single crystals are manufactured, each single crystal can be manufactured easily and at low cost so that each single crystal has a desired crystal quality without replacing the structure in the chamber.

EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated more concretely, this invention is not limited to these.
(Example)
Using the single crystal pulling apparatus 20 shown in FIG. 6, 300 kg of raw material polycrystalline silicon is charged into a quartz crucible 5 having a diameter of 32 inches (800 mm), and a horizontal magnetic field having a central magnetic field strength of 4000 gauss is applied and a diameter of 300 mm is applied. Four silicon single crystals were grown.

  At this time, in the first and second silicon single crystals, the defect region becomes a V region in the entire radial direction, and in the third and fourth silicon single crystals, the defect region becomes a V region in which the OSF ring exists. In addition, in order to manufacture four types of silicon single crystals in which the first and fourth silicon single crystals have a defect density lower than that of the second and third silicon single crystals, respectively, Each time growth is performed, the distance between the raw material melt surface and the heat shield member and the crystal pulling speed are adjusted and controlled so as to have the values shown in Table 1 below. Repeatedly, four single crystals were continuously grown from the same quartz crucible. Since the first to fourth silicon single crystals are manufactured in the same batch, the structure in the chamber is not replaced at all.

  Then, after each wafer was cut out from the obtained four silicon single crystals, surface grinding and polishing were performed to produce a sample wafer for inspection, and the defect area of the sample wafer was inspected by the foreign substance inspection apparatus. As a result, the sample wafers produced from the first and second silicon single crystals have the entire surface of the wafer in the V region, and the sample wafers produced from the third and fourth silicon single crystals are the outer periphery of the wafer. An OSF ring was observed in the part, and it was confirmed that the inner part was a V region.

  Further, the number of defects formed on the sample wafers made from the first to fourth silicon single crystals and having a size of 0.12 μm or more was inspected. Furthermore, in order to examine the distribution of the size of defects formed on the wafer, the number of defects having a size of 0.20 μm or more was also inspected. The results of the defect inspection are shown in Table 2 below.

  As shown in Table 2, as a result of measuring the defect density of the sample wafer produced from each silicon single crystal, relatively large defects having a size of 0.20 μm or more were observed in the first silicon single crystal. However, it was found that the number of defects having a size of 0.12 μm or more was significantly reduced as compared with the second silicon single crystal, and the defect density was low. Further, comparing the third silicon single crystal with the fourth silicon single crystal, it was found that the fourth silicon single crystal has a lower defect density.

  As described above, it was confirmed that the single crystal manufacturing method of the present invention can manufacture a plurality of single crystals having different desired crystal qualities, without replacing the structure in the chamber. .

  The present invention is not limited to the above embodiment. The above embodiment is merely an example, and the present invention has the same configuration as that of 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.

  For example, in the above description, a case where a silicon single crystal is mainly manufactured is described as an example. However, the present invention is not limited to this, and a single crystal such as a compound semiconductor single crystal is manufactured by the CZ method. The same can be applied to the case.

It is a graph which shows an example of the relationship between the distance between a raw material melt surface and a thermal insulation member, and the crystal temperature gradient G. It is a figure which shows the result of having test | inspected the defect area | region of the various silicon single crystal manufactured with the distance between the raw material melt surface of various conditions, and the heat-shielding member, and the pulling speed. It is a graph which shows the result of having investigated the defect density and defect size of the single crystal of A1, B1, and C1 shown in FIG. It is a graph which shows the result of having investigated the defect density and defect size of the single crystal of A2, B2, C2 shown in FIG. It is the graph which showed the relationship between the crystal pulling rate and the passage time of 1150-1080 degreeC band. It is the structure schematic which shows an example of the single crystal pulling apparatus which can be used when implementing the manufacturing method of the single crystal of this invention. (A) And (b) is the structure schematic which shows the other form of the heat-shielding member installed in a single crystal pulling apparatus. It is the structure schematic which shows an example of the conventional single crystal manufacturing apparatus. It is explanatory drawing showing the relationship between V / G and crystal defect distribution.

Explanation of symbols

1 ... main chamber, 2 ... pulling chamber, 3 ... single crystal (silicon single crystal),
4 ... Raw material melt (silicon melt), 5 ... Quartz crucible,
6 ... Graphite crucible, 7 ... Heater, 8 ... Insulating material,
9 ... Gas outlet, 10 ... Gas inlet, 11 ... Cooling auxiliary member,
12, 12a, 12b ... heat shield member, 13 ... holding shaft,
14 ... Wire, 15 ... Seed holder, 16 ... Seed crystal,
17 ... Lifting mechanism, 18 ... Drive control means, 19 ... CCD camera,
20 ... Single crystal pulling device, 21 ... Crucible drive mechanism,
22 ... Cooling cylinder, 23 ... Refrigerant inlet, 24 ... Protection member, 25 ... Magnetic field generator,
26 ... Gas flow straightening cylinder, 27 ... Holding member,
30 ... Single crystal manufacturing apparatus, 31 ... Gas rectifier cylinder, 32 ... Heat insulation member.

Claims (11)

  In a method of producing at least two single crystals by pulling a single crystal from a raw material melt in a chamber by the Czochralski method, the 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 in the vicinity of the solid-liquid interface is expressed by G (° C./mm), when growing the at least two single crystals, the melt surface of the raw material melt The crystal temperature is adjusted by adjusting the distance from the heat shielding member disposed opposite to the raw material melt surface in the chamber so that the single crystal grows to a target crystal standard every time the growth of the single crystal is started. By adjusting the gradient G, and further controlling the pulling rate V to a value at which the single crystal becomes the target crystal standard in accordance with the growth of each single crystal, the at least two single crystals are converted into each single crystal. Each has the desired crystal quality Method for producing a single crystal, characterized in that to manufacture a single crystal Te Unishi.   2. The method for producing a single crystal according to claim 1, wherein the at least two or more single crystals are produced so as to have different defect regions and / or different defect densities for each single crystal.   The method for producing a single crystal according to claim 1 or 2, wherein the at least two or more single crystals are grown from the same crucible.   The single crystal according to any one of claims 1 to 3, wherein when the single crystal is grown in a V region, a defect formed in the single crystal has a desired size. Crystal production method.   5. The unit according to claim 1, wherein a distance between the raw material melt surface and the heat shielding member is automatically adjusted according to a change condition obtained by performing a test in advance. Crystal production method.   The method for producing a single crystal according to any one of claims 1 to 5, wherein a distance between the raw material melt surface and the heat shielding member is controlled during the pulling of the straight body portion of the single crystal. .   The cooling chamber forcibly cooled with a cooling medium and a cooling auxiliary member installed below the cooling cylinder are disposed in the chamber so as to surround the growing single crystal. The method for producing a single crystal according to any one of claims 1 to 6.   The single crystal is pulled while applying a magnetic field having a central magnetic field strength in a range of 300 gauss to 6000 gauss. Production method.   9. The method for manufacturing a single crystal according to claim 1, wherein the single crystal to be manufactured is a silicon single crystal.   The method for producing a single crystal according to any one of claims 1 to 9, wherein the diameter of the straight body portion of the single crystal is 150 mm or more.   The single crystal manufactured by the manufacturing method of the single crystal as described in any one of Claims 1 thru | or 10.

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