JP2009292721A - Apparatus and method for pulling silicon single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for pulling a silicon single crystal by a CZ method where the acquisition rate and its assurance of a fault-free crystal (perfect crystal) can be enhanced. <P>SOLUTION: In the apparatus for pulling a single crystal to pull the silicon single crystal from a molten liquid, a method for enhancing the repeatability of crystal fault distribution in the surface of a silicon wafer cut from the silicon single crystal by tracing the variation amount of GAP being a distance from the bottom of a thermal shield to the surface of the molten liquid and minimizing the variation amount when the pulling of the silicon single crystal is performed in the apparatus equipped with the thermal shield surrounding the periphery of the silicon single crystal is used. As an example, a fault-free crystal region is formed over a wide region of a produced silicon ingot by the precise feedback control of the distance L of GAP basing on a measured value by a melt level detector and also the precise control of a crystal pulling velocity V. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a Czochralski method (CZ method) silicon single crystal pulling apparatus and method for pulling a silicon single crystal from a silicon melt, and in particular, a defect-free crystal (complete crystal) free from grown-in defects to a silicon ingot. The present invention relates to a CZ method silicon single crystal pulling apparatus and method that can be formed easily and with good reproducibility, and can acquire more defect-free crystal wafers from a silicon ingot.

  With the recent improvement in device characteristics associated with higher integration and miniaturization of semiconductor circuits, there is an increasing demand for reduction of crystal defects that occur in the manufacturing process of silicon single crystals. In order to meet this demand, when a silicon single crystal is manufactured by the CZ method, it is necessary to pull up the silicon single crystal by accurately controlling the defect distribution in the wafer surface.

  Here, when pulling up a silicon single crystal by the CZ method, the defect distribution of the crystal is generally reported to have a correlation with the pulling rate V and V / G expressed using the axial temperature gradient G near the melt. Has been. In order to grow a crystal having no crystal defects such as a void defect, a dislocation cluster, and an OSF ring, which is called a defect-free crystal (perfect crystal) (however, recently, there are those containing an OSF ring). ), It is necessary to control V / G with high accuracy.

For example, in Patent Document 1, as a condition for forming a defect-free region of a defect-free crystal (perfect crystal), the pulling rate of the crystal is V (mm / min), and the axial direction between the melting point of silicon and 1300 ° C. When the average temperature gradient in the crystal is G (° C./mm), the crystal may be pulled up by controlling the ratio represented by V / G to be 0.20 to 0.22 mm ² / ° C. min. Are listed.

  In addition to this, in order to control the defect distribution in the wafer plane determined by V / G, the axial temperature gradient at the crystal center during crystal growth is set to Gc, and the axial temperature gradient at the crystal outer periphery is set to Ge. The crystal growth rate V is controlled within a set value ± 0.02 mm, ΔG = Ge−Gc is controlled within 1 ° C./mm (see Patent Document 2), or Ge = Gc ± 0.3 ° C. (See Patent Document 3) has been proposed.

JP-A-8-330316 JP-A-11-199386 JP-A-11-199383

  However, in practice, it is not possible to accurately control V / G within a very narrow range (for example, Japanese Patent Application Laid-Open No. 8-330316) proposed as a condition for growing defect-free crystals (perfect crystals). It is extremely difficult.

  The reason is that, first, the quartz crucible inside the quartz crucible is actually fluctuated and the quartz crucible is deformed due to the radiant heat from the heater. It is mentioned that it is not.

  In addition, when a CZ method silicon single crystal pulling apparatus in which a heat shield is installed in the furnace is used, the heat shield expands and contracts when the silicon single crystal is pulled. As a result, the radial temperature distribution of the axial temperature gradient G in the vicinity of the interface during crystal growth changes, and the radial V / G changes. Therefore, only the pulling speed is controlled with high accuracy. However, it has been very difficult to obtain the same defect distribution with good reproducibility.

  Furthermore, even when the axial temperature gradient G is controlled, G actually changes every moment during crystal growth, and the radial distribution of the axial temperature gradient during crystal growth is accurately grasped. Since it is very difficult to do so, the intended defect distribution could not be obtained with good reproducibility within the wafer surface.

  This will be described in more detail. For example, in JP-A-8-330316, if G is uniform in the radial direction, for example, when G = 3.0 ° C./mm, the pulling speed V is 0.63. It is sufficient to control to ± 0.03 mm / min, but G is not uniform in the radial direction, and when the change in the radial direction of G reaches 10%, the allowable width becomes zero, It becomes impossible to produce defect-free crystals (perfect crystals). This means that a slight decrease in the uniformity of G in the radial direction substantially makes it impossible to manufacture defect-free crystals (perfect crystals), but the change in the radial direction of G becomes 10%. In the method proposed by Japanese Patent Laid-Open No. 8-330316, the production of defect-free crystals has to be extremely unstable.

  The present invention has been made in view of the problems as described above, and its purpose is to pull a CZ method silicon single crystal that can improve the acquisition rate and the certainty of defect-free crystals (perfect crystals). It is to provide an apparatus and method.

  In order to solve the above problems, the present inventors have conducted intensive research. As a result, in the CZ method silicon single crystal pulling apparatus provided with a heat shield in the furnace, the growth of defect-free crystals under the same conditions is performed. In this case, the change in the distance from the bottom surface of the heat shield to the melt surface (hereinafter simply referred to as “GAP”) greatly affects the temperature gradient G in the vicinity of the interface during crystal growth. It was found that this was the cause of variation in the defect distribution in the radial direction of the wafer surface.

  Further, the present inventors can suppress the change in the defect distribution in the wafer surface of the axial temperature gradient G by minimizing the amount of change in the GAP, and thereby in the wafer surface for each pulled crystal. The inventors have found that the reproducibility of the defect distribution can be improved, and have completed the present invention.

  For these reasons, the present invention provides the following method as a basic principle.

  (1) A single crystal pulling apparatus for pulling up a silicon single crystal from a silicon melt, wherein the silicon single crystal is pulled by a single crystal pulling apparatus having a heat shield surrounding the silicon single crystal. In addition, by tracking the amount of change in the distance from the bottom surface of the thermal shield to the melt surface and minimizing the amount of change, the distribution of crystal defects in the plane of the silicon wafer cut out from the silicon single crystal A method to improve reproducibility.

  Here, the method according to the above (1) has a problem of reproducibility of the crystal defect distribution in the plane of the silicon wafer, particularly in the radial direction, and the size of the crystal defect density is not a problem, but the crystal defect is zero. If the reproducibility is ensured, it means that the accuracy of manufacturing defect-free crystals has been increased.

  For this reason, according to the present invention, a method for producing a defect-free crystal with a certain degree of certainty is also provided. The following (2) is a general description of the method. In addition, in light of the basic principle of the present invention, in the process of pulling up a defect-free crystal, the manufacturing accuracy of the defect-free crystal is increased by giving a certain degree of freedom to increase or decrease the pulling rate of the silicon single crystal. (3) below is a general description of the present invention.

  Note that the “crystal defects” referred to here mean Grown-in defects such as void defects, dislocation clusters, and OSF rings. In addition, regarding the “within a predetermined allowable range” in the following (2), specific numerical values under a specific condition are clearly shown in the embodiments, but the numerical values are not limited to those shown therein, An appropriate value is set according to the situation (this “appropriate value” can be derived by a person skilled in the art by performing an experiment similar to the experiment shown in the Examples).

  (2) A single crystal pulling apparatus for pulling up a silicon single crystal from a silicon melt, wherein the silicon single crystal is pulled by a single crystal pulling apparatus having a heat shield surrounding the silicon single crystal. In addition, regarding the parameters set when forming a defect-free crystal region in the silicon single crystal pulled from the silicon melt, at least the distance from the bottom surface of the heat shield to the melt surface and the silicon single crystal. A method for increasing the accuracy of forming a defect-free crystal region by pulling a silicon single crystal while setting the crystal pulling speed to be within a predetermined allowable width.

  (3) A single crystal pulling apparatus for pulling up a silicon single crystal from a silicon melt, wherein the single crystal pulling apparatus includes a heat shield surrounding the silicon single crystal. In addition, when forming a defect-free crystal region in a silicon single crystal pulled from the silicon melt, silicon is increased by increasing the precision of controlling the distance from the bottom surface of the heat shield to the melt surface. A method of increasing the allowable range of increase / decrease in the pulling rate of a single crystal.

  A suitable CZ method silicon single crystal pulling apparatus for carrying out the method according to the present invention as described above is as follows.

  (4) A silicon single crystal pulling apparatus that pulls up a silicon single crystal from a silicon melt, wherein the silicon single crystal pulling apparatus includes a heat shield surrounding the silicon single crystal. With respect to parameters set when forming a defect-free crystal region in a silicon single crystal pulled up from at least the distance from the bottom surface of the heat shield to the melt surface and the pulling rate of the silicon single crystal are predetermined. The silicon single crystal pulling apparatus is characterized in that the silicon single crystal is pulled while being set so as to fall within an allowable width.

  (5) A silicon single crystal pulling apparatus that pulls up a silicon single crystal from a silicon melt, wherein the silicon single crystal pulling apparatus includes a heat shield surrounding the silicon single crystal. When a defect-free crystal region is formed in a silicon single crystal that is pulled up from, the distance from the bottom surface of the heat shield to the melt surface is precisely controlled, so that the pulling rate of the silicon single crystal is increased to some extent. A silicon single crystal pulling apparatus characterized in that the silicon single crystal can be pulled up with a margin.

  (6) A silicon single crystal pulling apparatus for pulling up a silicon single crystal from a silicon melt, wherein the silicon single crystal pulling apparatus includes a heat shield that surrounds the periphery of the silicon single crystal. Measure and track the distance from the bottom of the body to the melt surface, and manufacture a silicon ingot containing many defect-free crystal regions by pulling up the silicon single crystal while precisely controlling the distance as calculated. A silicon single crystal pulling apparatus characterized by that.

  (7) The silicon single crystal pulling apparatus according to any one of (4) to (6), further comprising magnetic field applying means for applying a magnetic field to the silicon melt.

  Note that it is preferable to apply a horizontal magnetic field of at least 2500 G as the magnetic field. If the magnetic field is 2000 G or less, the uniformity of G in the wafer surface is insufficient, and if it is 5000 G or more, it is considered that the defect-free rate is deteriorated. Therefore, the magnetic field is preferably adjusted in the range of 2500 G to 5000 G.

  By the way, silicon ingots manufactured by these devices include more defect-free regions than conventional ones, and the accuracy of forming defect-free regions is higher, so even when many silicon ingots are pulled up continuously. , There is almost no mixture of defective products (silicon ingots that hardly include defect-free regions). Therefore, in the present invention, the silicon ingot group which is continuously pulled up and manufactured as follows is also included in the scope.

  (8) A silicon ingot group including many defect-free regions manufactured by the silicon single crystal pulling apparatus according to any one of (4) to (7).

  Furthermore, the present invention includes the following method as a more specific embodiment.

  (9) A single crystal growth method characterized in that the set GAP is set to 0.2 to 0.5 times the pulling diameter, and pulling is performed by controlling the GAP within a set value ± 2.0 mm.

  (10) Adjust the crucible feed by accurately measuring the distance from the bottom surface of the heat shield to the melt surface using the melt level detector, and feeding back the difference between the measured GAP value and the set GAP to the crucible feed amount. To precisely control the GAP.

  (11) A method for growing a defect-free crystal (complete crystal), wherein the tolerance of the pulling rate is widened by applying a magnetic field.

  When pulling up the silicon single crystal, the radial distribution of the axial temperature gradient G during crystal growth can be changed with good reproducibility for each crystal in the longitudinal direction of the crystal by accurately controlling the distance L of the GAP. . Here, it is very difficult to keep G constant in the longitudinal direction of the crystal, but by accurately controlling the distance L of GAP, it is also possible to precisely control G in the radial direction. As a result, defect-free crystals can be manufactured.

  That is, according to the present invention, defect-free crystals can be formed easily and reproducibly in a silicon ingot, and more defect-free crystal wafers can be obtained from the silicon ingot.

It is the figure which showed the basic composition of the hot zone of the CZ method silicon | silicone single crystal pulling apparatus for implementing this invention. It is a block diagram which shows embodiment of the melt level detection apparatus which concerns on Japanese Patent Application 2000-083030 suitable for implementing this invention. It is a block diagram for demonstrating embodiment of the melt level detection apparatus based on Japanese Patent Application No. 2000-083030 suitable for implementing this invention. It is a figure for demonstrating the dispersion | variation in the distance L of measured GAP, and is the measured value of the distance L of GAP when it pulls up a silicon single crystal several times using a general CZ method silicon single crystal pulling apparatus. It is the graph which showed. In the figure, the vertical axis indicates the size of the GAP distance L, and the horizontal axis indicates the length of the silicon single crystal pulled from the silicon melt. It is a figure which shows the result when preparation of a defect-free crystal | crystallization is tried by setting the distance L of GAP constant according to the method currently performed conventionally and adjusting the crystal pulling speed V. In the figure, the upper figure is a graph showing the relationship between the length (horizontal axis) of the silicon single crystal pulled from the silicon melt and the distance L (vertical axis) of the crystal pulling speed V and GAP. The figure is a defect distribution diagram produced corresponding to the length of the silicon single crystal pulled from the silicon melt. As a control experiment, the distance L of the GAP is precisely feedback controlled based on the actual measurement value. On the other hand, the crystal pulling speed V is intentionally shifted from the set value, and the result when an attempt is made to produce a defect-free crystal. FIG. In the figure, the upper figure is a graph showing the relationship between the length (horizontal axis) of the silicon single crystal pulled from the silicon melt and the distance L (vertical axis) of the crystal pulling speed V and GAP. The figure is a defect distribution diagram produced corresponding to the length of the silicon single crystal pulled from the silicon melt. As a control experiment, while precisely controlling the crystal pulling speed V, the GAP distance L is a diagram showing a result when an attempt is made to produce a defect-free crystal by deliberately shifting from a set value. In the figure, the upper figure is a graph showing the relationship between the length (horizontal axis) of the silicon single crystal pulled from the silicon melt and the distance L (vertical axis) of the crystal pulling speed V and GAP. The figure is a defect distribution diagram produced corresponding to the length of the silicon single crystal pulled from the silicon melt. The GAP distance L is precisely feedback-controlled based on the actual measurement value from the melt level detection device according to the above Japanese Patent Application No. 2000-083030, and the crystal pulling speed V is also precisely controlled to produce a defect-free crystal. It is a figure which shows a result when trying. In the figure, the upper figure is a graph showing the relationship between the length (horizontal axis) of the silicon single crystal pulled from the silicon melt and the distance L (vertical axis) of the crystal pulling speed V and GAP. The figure is a defect distribution diagram produced corresponding to the length of the silicon single crystal pulled from the silicon melt. It is a figure which shows the result of having measured precisely about "allowable width" suggested in experiment.

[Definition of terms]
In this specification, “ingot” means a single crystal grown from a silicon melt, and is cut out from the ingot to produce a “wafer”.

  A defect-free crystal (perfect crystal) means a crystal in which neither a void (cavity) defect, an oxidation-induced stacking fault (OSF), nor a dislocation cluster exists. In addition, a defect-free region (perfect crystal region) or a defect-free region means that neither a void (cavity) defect, an oxidation-induced stacking fault (OSF), nor a dislocation cluster exists in the crystal. It means an area.

  “Thermal shield” is installed in the furnace to shield the radiant heat from the raw material melt liquid surface and the heat radiation from the heater in the furnace. It also works to rectify. Here, even if the main purpose of gas rectification is as long as the heat from the melt liquid surface or the heater is shielded in some form as a result, it functions as a heat shield according to the present invention. As long as the heat shielding is performed in some form, it is included in the concept of the “thermal shield” in the present invention.

  As the “magnetic field applying means for applying a magnetic field to the silicon melt”, for example, those disclosed in JP-A-56-45889 can be used. Further, among the magnetic field applying means, those that produce a cusp magnetic field can be those disclosed in Japanese Patent Application Laid-Open No. 58-217493.

  FIG. 1 is a diagram showing a basic configuration of a hot zone of a CZ method silicon single crystal pulling apparatus for carrying out the present invention. As shown in FIG. 1, a CZ silicon single crystal pulling apparatus for carrying out the present invention includes a crucible 21 that stores a silicon melt 13 and rotates itself, a heater 22 that heats the crucible 21, A heat shield 23 that surrounds the single crystal 11 that is pulled up while being rotated from the silicon melt 13 to adjust the amount of radiant heat to the single crystal 11, and a solenoid 27 that applies a magnetic field to the silicon melt 13. Including.

  Here, the heat shield 23 is generally made of a carbon member, and adjusts the temperature of the side surface of the single crystal 11 by shielding the radiant heat from the silicon melt 13 or the like. The heater 22 is preferably composed of a side heater 22a and a bottom heater 22b as shown in FIG.

  In carrying out the present invention, it is necessary to precisely track and control the distance L from the bottom surface 23a of the heat shield to the melt surface 13a. It is preferable to use a melt level detection apparatus according to -083030. In carrying out the present invention, when the distance L measured by the melt level detection device according to Japanese Patent Application No. 2000-083030 deviates from a preset range, for example, the crucible 21 is moved up and down. Adjust this to return it to the appropriate value.

  Here, FIG. 2 and FIG. 3 are block diagrams showing an embodiment of a melt level detection apparatus according to Japanese Patent Application No. 2000-083030. In the CZ method single crystal pulling apparatus equipped with this melt level detecting device, a distance measuring unit 8 based on the principle of triangulation is adopted, and laser light is applied to the silicon melt liquid surface 13a in this distance measuring unit 8. A laser beam irradiator for projecting and a light receiver for receiving the laser beam reflected from the silicon melt liquid surface 13a are provided.

  The laser beam 2 output from the distance measuring unit 8 is reflected by the scan mirror 28, passes through the incident window 18, passes through the quartz prism 20 installed in the chamber 17 of the pulling device, and passes through the silicon melt. It is projected on the liquid level 13a. The laser beam 2 projected on the silicon melt liquid surface 13a is once specularly reflected here, and the measurement spot 31 strikes the lower surface (bottom surface) 23a of the lower end of the heat shield 23. Then, the laser beam 2 irradiated as the measurement spot 31 on the bottom surface 23a of the heat shield 23 is scattered here, and a part of the reflected scattered light is specularly reflected by the silicon melt surface 13a (secondary reflected light). ), Enters the distance measuring unit 8 via the prism 20, the incident window 18, and the scan mirror 28. The distance measurement unit 8 based on the principle of triangulation calculates the distance (Dw) at that time from the distance between the laser beam irradiator and the light receiver, the irradiation angle of the laser beam and the light reception angle. To do.

  Next, by rotating or moving the scan mirror 28, the measurement spot 31 is moved to the upper surface 25 at the lower end portion of the heat shield 23, and reflected light (primary reflected light) therefrom is converted to the prism 20 and the incident window 18. Then, the light is received by the distance measuring unit 8 via the scan mirror 28 (path indicated by a broken line in the figure). And the distance to the upper surface of the lower end part of the heat shield 23 is calculated by the same method as when Dw is calculated, and the lower end of the heat shield 23 is added by adding the thickness 26 of the lower end part of the heat shield 23. The distance (Ds) to the back surface (bottom surface) 23a of the part is obtained.

  And the distance (GAP distance) L from the heat shield bottom surface 23a to the silicon melt liquid surface 13a is calculated by the following equation (1).

    GAP distance L = (Dw−Ds) / 2 (1)

[Setting conditions]
The case where the single crystal is pulled by precisely controlling the crystal pulling speed V and the distance L of the GAP using the CZ method silicon single crystal pulling apparatus as shown in FIG. In contrast, the formation of defect-free crystals was examined. The experiment was performed using a crystal having a diameter of 200 mm.

  The distribution of crystal defects can generally be investigated by immersing the crystal in an etchant and then observing its surface, but in this example, the void and dislocation clusters are subjected to unstirred Secco etching. Thus, the OSF was subjected to oxidative heat treatment at 780 ° C. for 3 hours and then at 1000 ° C. for 16 hours, and then subjected to light etching to investigate the distribution of defects.

  The GAP distance L was adjusted around 60 mm, and the crystal pulling speed V was adjusted to be about 0.4 mm / min in a steady state. The magnetic field applied was a 3000 G horizontal magnetic field.

[Measurement of GAP distance L]
The GAP distance L is measured by the melt level detection device according to the above Japanese Patent Application No. 2000-083030, the measured value is fed back to the crucible feed amount, and the GAP distance L is set within a set value ± 2.0 mm / min. At the same time, the crystal pulling speed V was controlled to be within a set value ± 0.01 mm / min.

[Dispersion of GAP distance L when using a general CZ method silicon single crystal pulling device]
First, using a CZ method silicon single crystal pulling apparatus as shown in FIG. 1 and controlling the GAP distance L to be constant by a conventional method in the apparatus, the silicon single crystal was pulled multiple times. . FIG. 4 shows the measured value of the distance L of the GAP when doing so.

  As shown in FIG. 4, it can be seen that when the control is performed by the conventional method, even if the GAP distance L is controlled to be constant, there is actually considerable variation. As described above, this is considered to be caused by the variation in the inner diameter of the quartz crucible, the sag and deformation of the quartz during the growth of the silicon single crystal, and the expansion and contraction of the heat shield.

[Control of crystal pulling speed V, control of GAP distance L]
<Control of crystal pulling speed V only (conventional method)>
First, in accordance with a conventional method, an attempt was made to produce a defect-free crystal by setting the GAP distance L constant and adjusting the crystal pulling speed V.

  Then, as shown in FIG. 5, the crystal pulling speed V was only slightly deviated from the set value due to its precise adjustment, but the GAP distance L is described in Japanese Patent Application No. 2000-083030. When measured by the melt level detection device, it was found that the actual measurement value (GAP actual value = GAP distance L) deviates greatly from the set value. This deviation reached 4 mm to 8 mm in the final stage of crystal pulling.

  Then, as shown in the defect distribution diagram shown below the graph, the defect-free region disappears and dislocation clusters appear as the GAP actual value deviates from the GAP set value.

  From FIG. 5, the reason why the conventional method could not make all the product target areas non-defective areas is that the actual GAP values deviated from the GAP set values. It can be inferred that this is the reason.

<Precise control of GAP distance L only (control experiment)>
This time, the GAP distance L is precisely feedback controlled based on the actual measurement value from the melt level detection device according to the above Japanese Patent Application No. 2000-083030, while the crystal pulling speed V is determined from the set value. I deliberately shifted it.

  Then, as shown in FIG. 6, the defect-free region disappears at a position where the crystal pulling speed V deviates significantly from the V setting value, and dislocation clusters and OSF rings have appeared.

  Therefore, even when the silicon single crystal is pulled up by precisely controlling the GAP distance L based on the actually measured value, the defect-free region disappears at the place where the crystal pulling speed V deviates greatly from the set value. At the same time, it can be seen that there is a certain tolerance, and when the crystal pulling speed V changes within a range not exceeding the tolerance, a defect-free region is formed.

<Precise control of crystal pulling speed V only (control experiment)>
Next, while precisely controlling the crystal pulling speed V, the GAP distance L was intentionally shifted from the set value.

  Then, as shown in FIG. 7, the defect-free region disappears at a location where the distance L of the GAP greatly deviates from the GAP set value, and dislocation clusters and OSF rings have appeared.

  Therefore, there is an allowable width for the GAP distance L when the crystal pulling speed V is precisely controlled, and when the GAP distance L changes within a range not exceeding the allowable width, the defect-free region is obtained. It can be seen that is formed.

<Precise control of GAP distance L and crystal pulling speed V (present invention)>
Finally, the GAP distance L was precisely feedback controlled based on the actual measurement value from the melt level detection apparatus according to the above Japanese Patent Application No. 2000-083030, and the crystal pulling speed V was also precisely controlled.

  As a result, as shown in FIG. 8, a defect-free crystal region was formed over a wide region of the manufactured silicon ingot. In this silicon ingot, most of the product target region is a defect-free crystal region, and the acquisition rate of the defect-free crystal silicon wafer is remarkably good.

[Allowable width]
Here, when the “allowable width” suggested in the above-mentioned experiment was measured precisely, the result shown in FIG. 9 was obtained.

  As shown in FIG. 9, when the GAP distance L is within a range of ± 2 mm, the crystal pulling speed V has an allowable width of ± 0.01 mm / min. However, as shown in FIG. 9, when the GAP distance L is shifted by 3 mm, the allowable width of the crystal pulling speed V is narrowed to a half of ± 0.005 mm / min.

  As described above, as the GAP distance L is properly controlled, the allowable range of the crystal pulling speed V is increased. In addition, in order to carry out the present invention, it is not necessary to apply a magnetic field, but the permissible width of the velocity V increases when a magnetic field is applied (in the case where a magnetic field is not applied when a magnetic field is applied). Rather, the optimum LAP distance L becomes narrower).

2 Laser beam 8 Distance measurement unit 11 Single crystal 13 Silicon melt 13a Melt liquid surface 17 Chamber 18 Entrance window 20 Quartz prism 21 Crucible 22 Heater 22a Side heater 22b Bottom heater 23 Heat shield 23a Heat shield bottom 25 Heat shield Upper surface of lower end of body 23 26 Thickness of lower end of heat shield 23 27 Solenoid 28 Scan mirror 31 Measurement spot L Distance from heat shield bottom 23a to melt surface 13a

Claims (7)

A single crystal pulling apparatus that pulls up a silicon single crystal from a silicon melt, and when pulling up the silicon single crystal with a single crystal pulling apparatus that includes a heat shield surrounding the silicon single crystal.
By tracking the amount of change in GAP, which is the distance from the bottom surface of the heat shield to the melt surface, and suppressing the amount of change to the minimum, the distribution of crystal defects in the plane of the silicon wafer cut out from the silicon single crystal To improve the reproducibility of images.   The set GAP which is a set value of the GAP is set to 0.2 to 0.5 times a pulling diameter, and the pulling is performed by controlling the GAP within a set value ± 2.0 mm. Method.   The distance from the bottom surface of the heat shield to the melt surface is accurately measured using a melt level detection device, and the difference between the measured GAP value and the set GAP is fed back to the crucible feed amount to adjust the crucible feed. The method according to claim 1 or 2.   The method according to any one of claims 1 to 3, wherein the allowable range of the pulling speed is widened by applying a magnetic field. A silicon single crystal pulling apparatus for pulling up a silicon single crystal from a silicon melt, wherein the silicon single crystal pulling apparatus includes a heat shield surrounding the silicon single crystal.
By measuring and tracking at least the amount of change in GAP, which is the distance from the bottom surface of the heat shield to the melt surface, and pulling up the silicon single crystal while minimizing the amount of change in the distance, there is no defect. A silicon single crystal pulling apparatus characterized by manufacturing a silicon ingot containing a large amount of crystal regions.   6. The silicon single crystal pulling apparatus according to claim 5, further comprising magnetic field applying means for applying a magnetic field to the silicon melt. A method for producing a silicon single crystal that pulls up a silicon single crystal from a silicon melt using a single crystal pulling apparatus including a heat shield surrounding the silicon single crystal to be pulled up,
A method for producing a silicon single crystal, wherein the amount of change in GAP, which is the distance from the bottom surface of the heat shield to the melt surface, is tracked and the silicon single crystal is pulled up while minimizing the amount of change. .

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