JP2008127216A - Production method of semiconductor single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method stably producing a nondefective silicon single crystal with good reproduction by a simple method and clearing the relation between the amount of variation caused when the capability for cooling a silicon single crystal by a cooler is changed and the amount of correction of other pulling conditions. <P>SOLUTION: In the production method, an endothermic amount Q of a cooler during pulling a silicon single crystal is measured to obtain a pulling speed correction amount Vq complying with the difference Q-Qref between a measurement value Q of the endothermic amount Q and a reference value Qref; then, a base value Vpg is modified by the pulling speed correction amount Vq; and the silicon single crystal is pulled at a modified pulling speed V. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor single crystal manufacturing method, and more particularly to a semiconductor single crystal manufacturing method in which a semiconductor single crystal is manufactured by pulling and growing the semiconductor single crystal while cooling the semiconductor single crystal with a cooler.

  A silicon single crystal is manufactured by pulling and growing by CZ (Czochralski method). The pull-grown silicon single crystal ingot is sliced into a silicon wafer. A semiconductor device is manufactured through a device process for forming a device layer on the surface of a silicon wafer.

  However, crystal defects or oxygen precipitation nuclei called “Grown-in defects” (defects introduced during crystal growth) occur during the growth of silicon single crystals. The glow-in defect is considered as a secondary defect of a point defect introduced during crystal growth.

  In recent years, with the progress of high integration and miniaturization of semiconductor circuits, it is no longer allowed for such a glow-in defect to exist near the surface layer of a silicon wafer in which devices are formed. For this reason, the possibility of producing defect-free crystals has been studied.

  Generally, crystal defects included in a silicon single crystal and deteriorating device characteristics are the following three types of defects.

a) Void defect (V defect) called COP (Crystal Originated Particle) etc., which is caused by the aggregation of vacancies.

b) OSF (Oxidation Induced Stacking Fault; R-OSF)
c) Dislocation loop clusters (interstitial silicon-type dislocation defects, I defects) generated by aggregation of interstitial silicon.

  V defects cause defects such as oxide breakdown voltage characteristics and element isolation in the semiconductor device process. R-OSF and I defects adversely affect leakage current characteristics and the like.

  A defect-free silicon single crystal is recognized or defined as a crystal that does not contain or substantially does not contain any of the above three types of defects.

  On the other hand, there is a method of manufacturing a silicon single crystal by arranging a cooler around a silicon single crystal that is pulled up from a melt in a CZ furnace, and pulling and growing the silicon single crystal while cooling the silicon single crystal with the cooler. It has been implemented conventionally.

  The cooler enhances the cooling effect of the silicon single crystal and makes it possible to increase the pulling speed. For this reason, the time for the growth of the silicon single crystal can be greatly shortened by installing the cooler. In addition, the shortening of the growth time of the silicon single crystal can suppress the deterioration of the furnace environment due to the evaporation from the silicon melt and the single crystal collapse due to the deterioration of the quartz crucible. Therefore, the productivity of the silicon single crystal can be improved by increasing the growth rate of the silicon single crystal.

  Further, it is known that the behavior of the above three types of defects changes depending on growth conditions such as the growth rate (pulling rate) of the silicon single crystal.

  That is, when viewed on a silicon wafer surface cut perpendicular to the single crystal pulling axis, the distribution of the three types of defects is greatly influenced by the growth rate (pulling rate) of the silicon single crystal. Depending on the growth rate (pulling rate) of the silicon single crystal, there may be no defect-free region on the entire surface of the silicon wafer. Further, depending on the growth rate (pulling rate) of the silicon single crystal, the entire surface of the silicon wafer may become a defect-free region.

  In recent years, there has been a growing demand for producing defect-free crystals that are defect-free regions in which the above three types of defects are eliminated over the entire surface of a silicon wafer.

  In Patent Document 1 below, a cooler is disposed in a CZ furnace so that the distance between the lower end thereof and the melt surface is 150 mm or less, and the growth condition V / G (V: growth rate (pulling rate)). , G: An invention in which the pulling device adjusts the pulling speed of the silicon ingot and adjusts the output of the heater so that the temperature gradient in the vicinity of the melting point of the silicon single crystal becomes a set value. .

  Patent Document 2 below describes an invention in which a cooler whose surface is blackened is installed in a CZ furnace to reduce variations in heat absorption from the silicon single crystal due to individual differences in the cooler. Yes.

  In Patent Document 3 below, the cooler is designed and placed in a CZ furnace so that the inner diameter and length of the cooler and the distance from the melt surface to the cooler are in proportion to the diameter of the silicon single crystal. The invention to do is described.

Patent Document 4 listed below describes an invention in which a cooling water channel is spirally arranged around a silicon single crystal with respect to the structure of a water-cooled cooler.
JP 2000-281478 A JP-A-2005-247629 JP 2001-220289 A JP 2002-255682 A

  In general, it is known that the growth rate (pulling rate) range and pulling conditions for forming a defect-free region excluding the three types of defects over the entire surface of the silicon wafer are very narrow. For this reason, it is said that the production of defect-free silicon single crystals requires very precise control of the pulling rate, lacks stability, and is said to be inferior in productivity. Therefore, it is required to stably manufacture a defect-free silicon single crystal in a simple manner with good reproducibility.

Even if the cooler is designed and arranged so as to obtain a desired cooling performance, the ability to cool the silicon single crystal by the cooler may differ from the initial one due to changes over time. In the CZ furnace, there are various in-furnace members such as a heat shielding plate in addition to the cooler. The ability to cool the silicon single crystal is affected by various manufacturing conditions such as the structure of the casing of the CZ furnace such as the heat shielding plate, the structure of the in-furnace member, and the power of the heater. In addition, although the said patent document 2 makes the dispersion | variation in the heat absorption from the silicon single crystal by the individual difference of a cooler small, it cannot cope with the change of the cooling capability by the time-dependent change mentioned above.

  For this reason, even when a defect-free silicon single crystal is obtained under a certain pulling condition, there is an example in which a defect-free silicon single crystal cannot be obtained because the ability to cool the silicon single crystal by the cooler has changed. .

However, none of the above Patent Documents 1 to 4 disclose how to adjust other pulling conditions when the ability to cool the silicon single crystal by the cooler changes.

The present invention has been made in view of such a situation, and clarifies the relationship between the amount of change when the ability to cool a silicon single crystal by a cooler and the amount of correction of other pulling conditions, and is a simple method. It is an object of the present invention to make it possible to stably produce defect-free silicon single crystals with good reproducibility.

The first invention is
In a method for manufacturing a semiconductor single crystal, a cooler is disposed around a semiconductor single crystal pulled from a melt, and the semiconductor single crystal is pulled and grown while cooling the semiconductor single crystal by the cooler.
While presetting the reference value of the endothermic amount of the cooler and the base value of the pulling rate under the production conditions capable of producing a defect-free semiconductor single crystal,
In order to produce a defect-free semiconductor single crystal, the relationship between the amount of change with respect to the reference value of the endothermic amount of the cooler and the amount of change with respect to the base value of the pulling speed is set in advance,
Measure the heat absorption of the cooler,
The amount of change in the pulling speed corresponding to the difference between the measured value of the endothermic amount of the cooler and the reference value is obtained based on the above relationship,
The semiconductor single crystal is pulled up by correcting the pulling rate by the calculated amount of change.

The second invention is the first invention,
When the difference between the measured value of the endothermic amount of the cooler and the reference value is 4% or more of the reference value, the pulling rate is corrected and the semiconductor single crystal is pulled up.

The third invention is the first invention,
When the difference between the measured value of the endothermic amount of the cooler and the reference value is 4% or more of the reference value, the pulling speed is corrected by a change amount of 0.01 mm / min or more, and the semiconductor single crystal is pulled up. It is characterized by.

The fourth invention is
In a method for manufacturing a semiconductor single crystal, a cooler is disposed around a semiconductor single crystal pulled from a melt, and the semiconductor single crystal is pulled and grown while cooling the semiconductor single crystal by the cooler.
While presetting the reference value of the endothermic amount of the cooler and the base value of the pulling rate under the production conditions capable of producing a defect-free semiconductor single crystal,
In order to produce a defect-free semiconductor single crystal, the relationship between the amount of change with respect to the reference value of the endothermic amount of the cooler and the amount of change with respect to the base value of the pulling speed is set in advance,
When an event that changes the endothermic amount of the cooler occurs, predict the amount of change of the endothermic amount of the cooler relative to the reference value,
The amount of change in the pulling speed corresponding to the predicted amount of change is obtained based on the relationship,
The semiconductor single crystal is pulled up by correcting the pulling rate by the calculated amount of change.

A fifth invention is the fourth invention,
When the predicted change in the endothermic amount of the cooler is 4% or more of the reference value, the pulling rate is corrected and the semiconductor single crystal is pulled up.

A sixth invention is the fourth invention,
When the predicted change in the endothermic amount of the cooler is 4% or more of the reference value, the semiconductor single crystal is pulled up by correcting the pulling rate by a change of 0.01 mm / min or more.

The seventh invention
In a method for manufacturing a semiconductor single crystal, a cooler is disposed so as to be movable up and down around a semiconductor single crystal pulled from a melt, and the semiconductor single crystal is pulled and grown while cooling the semiconductor single crystal with the cooler. ,
While presetting the reference value of the endothermic amount of the cooler and the reference position of the cooler under manufacturing conditions capable of producing a defect-free semiconductor single crystal,
In order to make the endothermic amount of the cooler a reference value, a relationship between the cooler elevating distance and the amount of change in the endothermic amount of the cooler is set in advance,
Measure the heat absorption of the cooler,
Based on the above relationship, calculate the cooler lift distance corresponding to the difference between the measured value of the heat absorption amount of the cooler and the reference value,
The semiconductor single crystal is pulled up by correcting the position of the cooler by the calculated elevation distance.

In an eighth aspect based on the seventh aspect,
When the difference between the measured value of the endothermic amount of the cooler and the reference value is 4% or more of the reference value, the position of the cooler is corrected and the semiconductor single crystal is pulled up.

The ninth invention
In a method for manufacturing a semiconductor single crystal, a cooler is disposed so as to be movable up and down around a semiconductor single crystal pulled from a melt, and the semiconductor single crystal is pulled and grown while cooling the semiconductor single crystal with the cooler. ,
While presetting the reference value of the endothermic amount of the cooler and the reference position of the cooler under manufacturing conditions capable of producing a defect-free semiconductor single crystal,
In order to make the endothermic amount of the cooler a reference value, a relationship between the cooler elevating distance and the amount of change in the endothermic amount of the cooler is set in advance,
When an event that changes the endothermic amount of the cooler occurs, predict the amount of change of the endothermic amount of the cooler relative to the reference value,
Based on the above relationship, the cooling distance of the cooler corresponding to the predicted change amount is obtained,
The semiconductor single crystal is pulled up by correcting the position of the cooler by the calculated elevation distance.

The tenth invention is the ninth invention,
When the predicted change in the endothermic amount of the cooler is 4% or more of the reference value, the position of the cooler is corrected and the semiconductor single crystal is pulled up.

The eleventh invention is
A semiconductor single crystal is manufactured by arranging a cooler around a semiconductor single crystal pulled from the melt and a heat shielding plate, and pulling and growing the semiconductor single crystal while cooling the semiconductor single crystal by the cooler. In the manufacturing method of
While preliminarily setting a reference value of the endothermic amount of the cooler under manufacturing conditions capable of manufacturing a defect-free semiconductor single crystal and a reference distance from the lower end of the heat shielding plate to the melt,
In order to set the endothermic amount of the cooler as a reference value, the relationship between the amount of correction of the distance from the lower end of the heat shield plate to the melt and the amount of change in the endothermic amount of the cooler is set in advance,
Measure the heat absorption of the cooler,
A distance correction amount from the lower end of the heat shield plate corresponding to the difference between the measured value of the endothermic amount of the cooler and the reference value is obtained based on the relationship,
The semiconductor single crystal is pulled up by correcting the distance from the lower end of the heat shielding plate to the melt by the calculated distance correction amount.

In a twelfth aspect based on the eleventh aspect,
When the difference between the measured value of the endotherm of the cooler and the reference value is 4% or more of the reference value, the distance from the bottom of the heat shield plate to the melt is corrected to pull up the semiconductor single crystal. And

The thirteenth invention
A semiconductor single crystal is manufactured by arranging a cooler around a semiconductor single crystal pulled from the melt and a heat shielding plate, and pulling and growing the semiconductor single crystal while cooling the semiconductor single crystal by the cooler. In the manufacturing method of
While preliminarily setting a reference value of the endothermic amount of the cooler under manufacturing conditions capable of manufacturing a defect-free semiconductor single crystal and a reference distance from the lower end of the heat shielding plate to the melt,
In order to set the endothermic amount of the cooler as a reference value, the relationship between the amount of correction of the distance from the lower end of the heat shield plate to the melt and the amount of change in the endothermic amount of the cooler is set in advance,
When an event that changes the endothermic amount of the cooler occurs, predict the amount of change of the endothermic amount of the cooler relative to the reference value,
A distance correction amount from the lower end of the heat shield plate corresponding to the predicted change amount to the melt is determined based on the relationship,
The semiconductor single crystal is pulled up by correcting the distance from the lower end of the heat shielding plate to the melt by the calculated distance correction amount.

In a fourteenth aspect based on the thirteenth aspect,
When the predicted change in the endothermic amount of the cooler is 4% or more of the reference value, the distance from the lower end of the heat shield plate to the melt is corrected to pull up the semiconductor single crystal.

  As shown in FIG. 5, the first invention measures the endothermic amount Q of the cooler 20 during the pulling of the silicon single crystal 10, and responds to the difference Q-Qref between the measured value Q of the endothermic amount Q and the reference value Qref. The pulling speed correction amount Vq is obtained, the base value Vpg is corrected by the pulling speed correction amount Vq, and the silicon single crystal 10 is pulled up at the corrected pulling speed V.

According to the first invention, the relationship between the change amount (ΔQ) when the ability to cool the silicon single crystal by the cooler is changed and the correction amount (Vq) of the pulling rate V is clarified, and the pulling rate is based on the relationship. Since V is corrected, the defect-free silicon single crystal 10 can be stably manufactured with good reproducibility by a simple method.

In addition, when the change amount ΔQ of the endothermic amount Q of the cooler 20 with respect to the reference value Qref is less than 4% of the reference value Qref, the experiment shows that there is almost no fluctuation in the pulling speed V at which the defect-free silicon single crystal 10 can be manufactured. It became clear. In addition, when the amount of change ΔQ of the heat absorption amount Q of the cooler 20 with respect to the reference value Qref is 4% or more of the reference value Qref, the pulling speed V is corrected to be changed from the base value Vpg by 0.01 mm / min or more. Thus, it has been experimentally clarified that if the silicon single crystal 10 is pulled up, the defect-free silicon single crystal 10 cannot be pulled up.

Therefore, in the second invention, the pulling speed V is not corrected from the base value Vpg, but when the amount of change ΔQ of the endothermic amount Q of the cooler 20 with respect to the reference value Qref is 4% or more of the reference value Qref. The silicon single crystal 10 is pulled up by modifying the pulling rate V so as to change from the base value Vpg.

In the third aspect of the invention, the pulling speed V is not corrected from the base value Vpg. However, when the amount of change ΔQ of the heat absorption amount Q of the cooler 20 with respect to the reference value Qref is 4% or more of the reference value Qref, the pulling speed V is increased. The silicon single crystal is pulled up by 10 by correcting the speed V so as to change from the base value Vpg by 0.01 mm / min or more.

In the first invention described above, the pulling speed V is corrected by capturing the change in the endothermic amount Q of the cooler 20 during pulling of the silicon single crystal 10. In contrast, in the fourth aspect of the invention, when an event occurs in which the endothermic amount Q of the cooler 20 changes, the change in the endothermic amount Q of the cooler 20 is predicted and the pulling speed V is corrected.

That is, in the fourth invention, as shown in FIG. 7, when an event occurs in which the endothermic amount Q of the cooler 20 changes, the amount of change ΔQ with respect to the reference value Qref of the endothermic amount Q of the cooler 20 is predicted. A pulling speed correction amount Vq corresponding to the changed amount ΔQ is obtained, the base value Vpg is corrected by the pulling speed correction amount Vq, and the silicon single crystal 10 is pulled at the corrected pulling speed V.

According to the fourth invention, the relationship between the change amount (ΔQ) when the ability to cool the silicon single crystal 10 by the cooler 20 is changed and the correction amount (Vq) of the pulling speed V is clarified, and based on the relationship. Since the pulling speed V is corrected in accordance with the predicted change amount, the defect-free silicon single crystal 10 can be stably manufactured with good reproducibility by a simple method.

In the fifth invention, similarly to the second invention, when the predicted change amount ΔQ of the endothermic amount Q of the cooler 20 is less than 4% of the reference value Q, the pulling speed V is not corrected, and the predicted change amount ΔQ is When the reference value Q is 4% or more, the pulling rate V is modified to change from the base value Vpg, and the silicon single crystal 10 is pulled.
In the sixth invention, similarly to the third invention, when the predicted change amount ΔQ of the endothermic amount Q of the cooler 20 is less than 4% of the reference value Q, the pulling speed V is not corrected, and the predicted change amount ΔQ is When the reference value Q is 4% or more of the reference value Q, the pulling speed V is corrected to change from the base value Vpg by 0.01 mm / min or more, and the silicon single crystal 10 is pulled.

In the first invention described above, the pulling speed V is corrected when the heat absorption amount Q of the cooler 20 changes from the reference value Qref during pulling of the silicon single crystal 10. On the other hand, in the seventh invention, when the endothermic amount Q of the cooler 20 changes during the pulling of the silicon single crystal 10, the position P of the cooler 20 is corrected so as to eliminate the change and return to the reference value Qref. That's it.

That is, in the seventh aspect, as shown in FIG. 8, the endothermic amount Q of the cooler 20 is measured, and the elevation distance of the cooler 20 corresponding to the difference ΔQ between the measured value Q of the endothermic amount Q of the cooler 20 and the reference value Qref. The position P of the cooler 20 is corrected by Pq, and the silicon single crystal 10 is pulled up.

According to the seventh invention, the relationship between the change amount (ΔQ) when the ability to cool the silicon single crystal 10 by the cooler 20 is changed and the correction amount (Pq) of the cooler position P is clarified, and based on these relationships. Since the position P of the cooler 20 is corrected, the defect-free silicon single crystal 10 can be stably manufactured with good reproducibility by a simple method.

In the eighth invention, similarly to the second invention, when the change amount ΔQ of the endothermic amount Q of the cooler 20 is less than 4% of the reference value Q, the position P of the cooler 20 is not corrected, and the change amount ΔQ is When it is 4% or more of the reference value Q, the position P of the cooler 20 is corrected and the silicon single crystal 10 is pulled up.
In the seventh invention described above, the position P of the cooler 20 is corrected by capturing the change in the heat absorption amount Q of the cooler 20 during the pulling of the silicon single crystal 10. In contrast, the ninth aspect of the invention corrects the position P of the cooler 20 by predicting the change of the heat absorption amount Q of the cooler 20 when an event occurs in which the heat absorption amount Q of the cooler 20 changes.

That is, in the ninth aspect, as shown in FIG. 10, when an event occurs in which the endothermic amount Q of the cooler 20 changes, an amount of change ΔQ with respect to the reference value Qref of the endothermic amount Q of the cooler 20 is predicted. The cooler position correction amount Pq corresponding to the changed amount ΔQ is obtained, the reference position Ppg of the cooler 20 is corrected by the cooler position correction amount Pq, and the silicon single crystal 10 is drawn at the corrected cooler position P. increase.

According to the ninth aspect, the relationship between the change amount (ΔQ) when the ability to cool the silicon single crystal 10 by the cooler 20 is changed and the cooler position correction amount (Pq) is clarified, and the prediction is made based on the relationship. Since the cooler position P is corrected according to the amount of change, the defect-free silicon single crystal 10 can be stably manufactured with good reproducibility by a simple method.

In the tenth invention, similarly to the second invention, when the predicted change amount ΔQ of the endothermic amount Q of the cooler 20 is less than 4% of the reference value Q, the position P of the cooler 20 is not corrected, and the predicted change amount ΔQ However, when it is 4% or more of the reference value Q, the position P of the cooler 20 is corrected and the silicon single crystal 10 is pulled up.
In the first invention described above, the pulling speed V is corrected when the heat absorption amount Q of the cooler 20 changes from the reference value Qref during pulling of the silicon single crystal 10. On the other hand, in the eleventh aspect of the invention, when the endothermic amount Q of the cooler 20 changes during the pulling of the silicon single crystal 10, the change is eliminated and the melt is returned from the lower end of the heat shielding plate 8 to return to the reference value Qref. Correct the distance D up to 5.

That is, in the eleventh aspect, as shown in FIG. 8, the endothermic amount Q of the cooler 20 is measured, and the heat shielding is performed by a distance Dq corresponding to the difference ΔQ between the measured value Q of the endothermic amount Q of the cooler 20 and the reference value Qref. The distance D from the lower end of the plate 8 to the melt 5 is corrected, and the silicon single crystal 10 is pulled up.

According to the eleventh invention, the amount of change (ΔQ) when the ability to cool the silicon single crystal 10 by the cooler 20 changes, and the amount of correction (Dq) of the distance D from the lower end of the heat shielding plate 8 to the melt 5. Since the distance D is corrected based on these relationships, the defect-free silicon single crystal 10 can be stably manufactured with good reproducibility by a simple method.

In the twelfth invention, as in the second invention, when the change amount ΔQ of the endothermic amount Q of the cooler 20 is less than 4% of the reference value Q, the distance D is not corrected, and the change amount ΔQ is equal to the reference value Q. When the distance is 4% or more, the distance D is corrected and the silicon single crystal 10 is pulled up.
In the above-described eleventh invention, the distance D from the lower end of the heat shielding plate 8 to the melt 5 is corrected by capturing the change in the heat absorption amount Q of the cooler 20 while pulling up the silicon single crystal 10. In contrast, in the thirteenth aspect, when an event occurs in which the heat absorption amount Q of the cooler 20 changes, the change in the heat absorption amount Q of the cooler 20 is predicted and the distance D is corrected.

That is, in the thirteenth aspect, as shown in FIG. 14, when an event occurs in which the endothermic amount Q of the cooler 20 changes, an amount of change ΔQ with respect to the reference value Qref of the endothermic amount Q of the cooler 20 is predicted. The distance correction amount Dq corresponding to the changed amount ΔQ is obtained, the reference distance Dpg is corrected by the distance correction amount Dq, and the silicon single crystal 10 is pulled up by the corrected distance D.

According to the thirteenth invention, the amount of change (ΔQ) when the ability to cool the silicon single crystal 10 by the cooler 20 changes, and the amount of correction (Dq) of the distance D from the lower end of the heat shielding plate 8 to the melt 5. Since the distance D is corrected according to the predicted change amount based on the relationship, the defect-free silicon single crystal 10 can be stably manufactured with good reproducibility. .

In the fourteenth invention, as in the second invention, when the predicted change amount ΔQ of the endothermic amount Q of the cooler 20 is less than 4% of the reference value Q, the distance D is not corrected, and the predicted change amount ΔQ is the reference. When it is 4% or more of the value Q, the distance D is corrected and the silicon single crystal 10 is pulled up.

  Hereinafter, embodiments of a method for producing a semiconductor single crystal according to the present invention will be described with reference to the drawings.

Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a side view of an exemplary configuration of a silicon single crystal manufacturing apparatus used in the embodiment.

  As shown in FIG. 1, a single crystal pulling apparatus 1 according to the embodiment includes a CZ furnace (chamber) 2 as a single crystal pulling container.

  In the CZ furnace 2, there is provided a quartz crucible 3 for melting a polycrystalline silicon raw material and storing it as a melt 5. The quartz crucible 3 is covered with a graphite crucible 11 on the outside. Around the quartz crucible 3, a heater 9 for heating and melting the polycrystalline silicon raw material in the quartz crucible 3 is provided. The heater 9 is formed in a cylindrical shape. The output of the heater 9 (power; kW) is controlled, and the heating amount for the melt 5 is adjusted. For example, the temperature of the melt 5 is detected, and the output of the heater 9 is controlled so that the detected temperature is a feedback amount and the temperature of the melt 5 becomes the target temperature.

  A pulling mechanism 4 is provided above the quartz crucible 3. The pulling mechanism 4 includes a pulling shaft 4a and a seed chuck 4c at the tip of the pulling shaft 4a. The seed crystal 14 is gripped by the seed chuck 4c.

  In the quartz crucible 3, polycrystalline silicon (Si) is heated and melted. When the temperature of the melt 5 is stabilized, the pulling mechanism 4 operates and the silicon single crystal 10 (silicon single crystal) is pulled from the melt 5. That is, the pulling shaft 4 a is lowered and the seed crystal 14 held by the seed chuck 4 c at the tip of the pulling shaft 4 a is deposited on the melt 5. After the seed crystal 14 is adjusted to the melt 5, the pulling shaft 4a moves up. As the seed crystal 14 held by the seed chuck 4c rises, the silicon single crystal 10 grows.

At the time of pulling up, the quartz crucible 3 is rotated by the rotating shaft 15. The pulling shaft 4a of the pulling mechanism 4 rotates in the opposite direction or the same direction as the rotating shaft 15.

  The rotary shaft 15 can be driven in the vertical direction, and the quartz crucible 3 can be moved up and down and moved to an arbitrary crucible position.

  By shutting off the outside air from the CZ furnace 2, the inside of the furnace 2 is maintained in a vacuum (for example, about 20 Torr). That is, argon gas 7 as an inert gas is supplied to the CZ furnace 2 and is exhausted from the exhaust port of the CZ furnace 2 by a pump. Thereby, the inside of the furnace 2 is depressurized to a predetermined pressure.

  Various evaporants are generated in the CZ furnace 2 during the single crystal pulling process (one batch). Therefore, the argon gas 7 is supplied to the CZ furnace 2 and exhausted together with the evaporated substance outside the CZ furnace 2 to remove the evaporated substance from the CZ furnace 2 and clean it. The supply flow rate of the argon gas 7 is set for each process in one batch.

  As the silicon single crystal 10 is pulled up, the melt 5 decreases. As the melt 5 decreases, the contact area between the melt 5 and the quartz crucible 3 changes, and the amount of dissolved oxygen from the quartz crucible 3 changes. This change affects the oxygen concentration distribution in the pulled silicon single crystal 10.

  A heat shielding plate 8 (gas rectifying cylinder) is provided above the quartz crucible 3 and around the silicon single crystal 10. The heat shielding plate 8 guides an argon gas 7 as a carrier gas supplied from above into the CZ furnace 2 to the center of the melt surface 5a, and further passes through the melt surface 5a so that the peripheral portion of the melt surface 5a. Lead to. The argon gas 7 is discharged together with the gas evaporated from the melt 5 from an exhaust port provided in the lower part of the CZ furnace 2. For this reason, the gas flow rate on the liquid surface can be stabilized, and the oxygen evaporated from the melt 5 can be maintained in a stable state.

  The heat shielding plate 8 insulates and shields the seed crystal 14 and the silicon single crystal 10 grown by the seed crystal 14 from radiant heat generated in a high-temperature portion such as the quartz crucible 3, the melt 5, and the heater 9. Further, the heat shielding plate 8 prevents the silicon single crystal 10 from being impeded by impurities (for example, silicon oxide) generated in the furnace and inhibiting single crystal growth. The magnitude of the distance D between the lower end of the heat shielding plate 8 and the melt surface 5a can be adjusted by raising and lowering the rotating shaft 15 and changing the vertical position of the quartz crucible 3. Further, the distance D may be adjusted by moving the heat shielding plate 8 in the vertical direction by the lifting device.

  A cooler 20 is disposed around the silicon single crystal 10 pulled from the melt 5. The cooler 20 is disposed inside the heat shielding plate 8. The cooler 20 is provided for pulling and growing the silicon single crystal 10 while cooling the silicon single crystal 10.

  In the present embodiment, it is assumed that the water-cooled cooler 20 is disposed in the CZ furnace 2.

  FIG. 2 is a configuration diagram of a cooling water circuit of the cooler 20.

  The cooler 20 is configured, for example, as a tube 21 formed in a spiral shape so as to surround the silicon single crystal (ingot) 10 being pulled up. An inlet 21 a of the pipe 21 is connected to a supply pipe 22 outside the CZ furnace 2. An outlet 21 b of the pipe 21 is connected to a return pipe 23 outside the CZ furnace 2. The discharge port of the pump 24 communicates with the supply pipe 22. The tank 25 communicates with the return pipe 23. When the pump 24 is operated, the cooling water is pumped and flows through the pipe 21 at a predetermined flow rate via the supply pipe 22 and the inlet 21a of the pipe 21. Thereby, heat exchange is performed between the cooling water inside the tube 21 and the heat source including the silicon single crystal 10 around the tube 21, and the heat radiated from the heat source including the silicon single crystal 10 is absorbed. The cooling water that has absorbed the heat is discharged from the outlet 21 b of the pipe 21 to the tank 25 through the return pipe 23. The pump 24 sucks up the cooling water in the tank 25 and pumps the cooling water again. As described above, the cooling water circulates in the cooler 20, whereby the silicon single crystal 10 being pulled is cooled. In FIG. 2, a heat exchanger for radiating the cooling water that has absorbed heat is omitted.

  Here, the endothermic amount Q (W) of the cooler 20 is defined as follows: Tout is the temperature (K) of the cooling water on the outlet 21b side of the pipe 21; Tin is the temperature (K) of the cooling water on the inlet 21a side of the pipe 21; The flow rate of cooling water (g / sec) and c can be expressed by the following formula (1), where water is the specific heat of water (about 4.19 J / g.K).

Q = (Tout−Tin) × f × c (1)
In order to obtain the endothermic amount Q of the cooler 20, for example, as shown in FIG. 2, a temperature measurement sensor 31 is provided in the supply pipe 22, and a temperature measurement sensor 32 and a flow meter 33 are provided in the return pipe 23. The sensor 31 measures the inlet side cooling water temperature Tin, the temperature measurement sensor 32 measures the outlet side cooling water temperature Tout, the flow meter 33 measures the cooling water flow rate f, and the measured inlet side cooling water temperature Tin, outlet The heat absorption amount Q may be calculated by substituting the side cooling water temperature Tout into the above equation (1).

The cooler 20 enhances the cooling effect of the silicon single crystal 10 and enables the pulling speed to be increased. For this reason, the time for the silicon single crystal 10 to grow can be significantly shortened by installing the cooler 20. Further, the shortening of the growth time of the silicon single crystal 10 can suppress the deterioration of the furnace environment due to the evaporated material from the silicon melt 5 and the collapse of the single crystal due to the deterioration of the quartz crucible 3. Therefore, the productivity of the silicon single crystal 10 can be improved by increasing the growth rate V of the silicon single crystal 10.

In the apparatus according to the present embodiment, the cooler 20 is disposed so as to be movable up and down, and the position P of the cooler 20 is adjustable.

(First embodiment)
An experiment was conducted on how the pulling conditions under which the defect-free silicon single crystal 10 can be manufactured with the apparatus configuration shown in FIGS. 1 and 2 vary depending on the heat absorption amount Q of the cooler 20. The experimental conditions are as follows.

First, the size of the hot zone of the CZ furnace 2 is 22 inches. A quartz crucible 3 was loaded with 120 kg of raw material, and a total of eight ingots of silicon single crystal 10 having a diameter of 200 mm were pulled up. For each ingot that has been pulled up, a number that identifies the ingot in the order in which it was pulled up, NO. 1, NO. 2, NO. 3, NO. 4, NO. 5, NO. 6, NO. 7, NO. 8 was given. The pulling conditions were managed so that all the ingots except the pulling speed V were the same. The cooling water flow rate of the cooler 20 was set to 133 (g / sec).

NO. After the completion of pulling up the ingot 5, the tube of the cooler 20 was baked for a short time without flowing cooling water through the cooler 20. In addition, the observable change such as discoloration of the tube was not observed by this baking.

3 and 4 show the experimental results.

FIG. 3 shows the relationship between the axial position of the silicon single crystal 10, that is, the length of the ingot straight body portion and the endothermic amount Q (kW) of the cooler 20 for each ingot number.

4A shows the relationship between the axial position of the silicon single crystal 10, that is, the length of the ingot straight body portion and the variation ΔV (mm / min) of the pulling speed V with respect to the base value Vpg. 1, NO. 2, NO. 3, NO. 4, NO. 5 for each ingot.

4B shows the relationship between the axial position of the silicon single crystal 10, that is, the length of the ingot straight body and the amount of change ΔV (mm / min) of the pulling speed V with respect to the base value Vpg. 6, NO. 7, NO. 8 for each ingot.

Here, the base value Vpg of the pulling speed V is a pulling speed when the defect-free silicon single crystal 10 can be manufactured. In FIG. The base value Vpg at the position is set to zero.

In FIG. 4, those having void defects (V defects) are indicated by も の, those having no defects are indicated by ●, and those having dislocation clusters (I defects) are indicated by ×.

From FIG. 1 to NO. Compared to when each ingot of No. 5 is pulled up, NO. 6 to NO. It can be seen that the heat absorption amount Q of the cooler 20 is reduced by about 1 kW when each of the ingots 8 is pulled up. FIG. 4 shows the results of defect evaluation for each of these ingots. About the void defect (V defect), the presence or absence of the defect was evaluated by the infrared tomography method. Moreover, about the dislocation cluster (I defect), the presence or absence of the defect was evaluated by observation with an optical microscope after secco etching. If any of the defects existed in the wafer surface, it was determined as “defect”, and if any defect was not detected, it was determined as “no defect”.

As can be seen from FIG. 4A, when the amount of change ΔV of the pulling rate V with respect to the base value Vpg is near zero, that is, when the pulling rate V is near the base value Vpg, a defect-free silicon single crystal 10 is manufactured. I was able to. Further, the endothermic amount Q of the cooler 20 under the manufacturing conditions capable of manufacturing the defect-free silicon single crystal 10 is defined as a reference value Qref.

As can be seen from FIG. 4B, when the endothermic amount Q of the cooler 20 is reduced by about 1 kW from the reference value Qref, the defect-free silicon single crystal 10 cannot be manufactured when the pulling rate V is near the base value Vpg. It was. It can be seen that in order to manufacture the defect-free silicon single crystal 10, the pulling rate V needs to be further reduced by 0.01 mm / min or more from the base value Vpg.

NO. 1 to NO. 5 (a) showing the time of pulling up each ingot in FIG. 6 to NO. In FIG. 4 (b) showing when each ingot 8 is pulled up, there is a difference of about 1 kW in the heat absorption amount Q of the cooler 20. This corresponds to 5 to 6% of the reference value Qref of the heat absorption amount Q of the cooler 20.

Thus, when the endothermic amount Q of the cooler 20 varies by about 5 to 6% of the reference value Qref, the appearance speed of defects changes, and the pulling speed V must be changed from the base value Vpg by 0.01 mm / min or more. The defect-free silicon single crystal 10 cannot be manufactured.

In addition, NO. 1 to NO. Even when each ingot of No. 5 was pulled up (FIG. 4A), the endothermic amount Q of the cooler 20 varied by about 3% to 4% of the reference value Qref. However, at that time, the defect appearance rate hardly changed, and the defect-free silicon single crystal 10 could be manufactured with the pulling rate V in the vicinity of the base value Vpg.

Thus, when the endothermic amount Q of the cooler 20 varies by about 3% to 4% of the reference value Qref, the appearance speed of defects hardly changes, and the pulling speed V remains in the vicinity of the base value Vpg without any defects. The silicon single crystal 10 can be manufactured.

Accordingly, the reference value Qref of the endothermic amount Q of the cooler 20 and the base value Vpg of the pulling speed V under the manufacturing conditions capable of manufacturing the defect-free silicon single crystal 10 are set in advance, and the endothermic amount of the cooler 20 is set. If the change amount ΔQ of Q with respect to the reference value Qref is less than 4% of the reference value Qref, the pulling speed V is not corrected from the base value Vpg, but the change amount ΔQ of the endothermic amount Q of the cooler 20 with respect to the reference value Qref is When the reference value Qref is 4% or more, the pulling speed V is corrected to be changed by 0.01 mm / min or more from the base value Vpg, and the silicon single crystal may be pulled up by 10. Become.

FIG. 5 shows a control block diagram of the first embodiment.

As shown in FIG. 5, this control measures the endothermic amount Q of the cooler 20 during the pulling of the silicon single crystal 10, and depends on the difference Q−Qref between the measured value Q of the endothermic amount Q and the reference value Qref. The pulling speed correction amount Vq is obtained, the base value Vpg is corrected by the pulling speed correction amount Vq, and the silicon single crystal 10 is pulled up at the corrected pulling speed V.

  It is assumed that the specific heat c of water, the reference value Qref of the heat absorption amount Q of the cooler 20, the pulling speed program Vpg, and the pulling speed correction amount Vq are stored in advance in the storage device.

That is, the inlet side cooling water temperature Tin is measured by the temperature measurement sensor 31 (process 101), the outlet side cooling water temperature Tout is measured by the temperature measurement sensor 32 (process 102), and the inlet side cooling water temperature is calculated from the outlet side cooling water temperature Tout. Tin is subtracted to obtain Tout-Tin (process 103). On the other hand, the coolant flow rate f is measured by the flow meter 33 (process 104).

  Then, the specific heat c of the water is read from the storage device, and based on the specific heat c of the water, Tout−Tin determined as described above, and the flow rate f of the cooling water, the above equation (1) (Q = ( (Tout−Tin) × f × c) is performed, and the heat absorption amount Q (kW) of the cooler 20 is obtained (processing 105).

The reference value Qref of the heat absorption amount Q of the cooler 20 is read from the storage device (process 106), the reference value Qref is subtracted from the current heat absorption amount Q of the cooler 20 measured as described above, and the heat absorption amount Q of the cooler 20 is calculated. A change amount ΔQ (= Q−Qref) with respect to the reference value Qref is obtained (processing 107).

Next, the pulling speed V is corrected according to the amount of change ΔQ of the endothermic amount Q of the cooler 20 with respect to the reference value Qref (processing 108 to 111).

FIG. 6A shows a program of the pulling speed V, that is, the base value Vpg corresponding to the length (axial position) of the silicon single crystal 10. FIG. 6B shows the pulling speed correction amount Vq in correspondence with the length (axial position) of the silicon single crystal 10. FIG. 6C shows the corrected pulling speed V corresponding to the length (axial position) of the silicon single crystal 10.

As shown in FIG. 6B, the pulling speed correction amount Vq is the amount of change in heat absorption Q of the cooler 20 described above when the change amount ΔQ (= Q−Qref) with respect to the reference value Qref is positive, that is, the measured heat absorption amount. When Q increases from the reference value Qref, it has a positive characteristic L1, and when the change amount ΔQ (= Q−Qref) is negative, that is, the measured heat absorption amount Q decreases from the reference value Qref. In some cases, it has a negative characteristic L2. The absolute value of the pulling speed correction amount Vq increases in proportion to the magnitude of the absolute value of the change amount ΔQ (= Q−Qref) with respect to the reference value Qref of the heat absorption amount Q of the cooler 20 described above. However, as described above, when the amount of change ΔQ of the endothermic amount Q of the cooler 20 with respect to the reference value Qref is 3% or less of the reference value Qref, the pulling speed correction amount Vq is zero. When the change amount ΔQ is 4% or more of the reference value Qref, the pulling speed correction amount Vq is 0.01 mm / min or more and increases in proportion to the absolute value of the change amount ΔQ. Is set.

The pull-up speed correction amount Vq corresponding to the change amount ΔQ (= Q−Qref) of the endothermic amount Q of the cooler 20 with respect to the reference value Qref is read (process 108), and the pull-up speed V program, that is, the base value Vpg is read. (Processing 109). Then, both are added (processing 110), and a corrected pulling speed V (= Vpg + Vq) is obtained. That is, when the amount of change ΔQ (= Q−Qref) of the endothermic amount Q of the cooler 20 with respect to the reference value Qref is positive, that is, when the measured endothermic amount Q increases from the reference value Qref, the base value Vpg. When the pulling speed V is corrected with the characteristic L11 that increases with respect to, and the change amount ΔQ (= Q−Qref) is negative, that is, when the measured heat absorption amount Q decreases from the reference value Qref, The pulling speed V is corrected with the characteristic L12 that decreases with respect to the base value Vpg (processing 111).

The pulling speed V of the pulling shaft 4a of the pulling mechanism 4 is adjusted to the corrected pulling speed V (= Vpg + Vq), and the silicon single crystal 10 is pulled up.

As described above, according to the present embodiment, the relationship between the change amount (ΔQ) when the ability to cool the silicon single crystal 10 by the cooler 20 and the correction amount (Vq) of the pulling speed V is clarified. Since the pulling speed V is corrected based on the relationship, the defect-free silicon single crystal 10 can be stably manufactured with good reproducibility by a simple method.

(Second embodiment)
In the first embodiment described above, the pulling speed V is corrected by capturing the change in the endothermic amount Q of the cooler 20 during pulling of the silicon single crystal 10. However, when the event that the heat absorption amount Q of the cooler 20 changes occurs, it is possible to predict the change in the heat absorption amount Q of the cooler 20 and correct the pulling speed V.

FIG. 7 shows a control block diagram of the second embodiment.

As shown in FIG. 7, this control predicts a change amount ΔQ with respect to the reference value Qref of the endothermic amount Q of the cooler 20 when an event in which the endothermic amount Q of the cooler 20 changes occurs. The pulling speed correction amount Vq corresponding to the change amount ΔQ is obtained, the base value Vpg is corrected by the pulling speed correction amount Vq, and the silicon single crystal 10 is pulled up at the corrected pulling speed V. . It is assumed that the predicted change amount ΔQ of the endothermic amount Q of the cooler 20 for each event, the pulling speed program, and the pulling speed correction amount Vq are stored in advance in the storage device.

Here, the event means that, when the single crystal pulling apparatus 1 (pulling machine) is changed, or when it is changed to a different cooler 20, the silicon single crystal 10 is pulled up halfway but becomes polycrystalline, so it is immersed again in the melt 5. For example, when it is pulled up after being re-dissolved and re-dissolved, or when shifting to the next batch (every time it changes). The occurrence of these events is automatically detected, and a signal indicating the type of event and the occurrence of the event is output. Alternatively, when an event occurs, the operator manually operates the operation panel to output a signal indicating the type of event and the occurrence of the event (process 201).

Next, the predicted change amount ΔQ (= Q−Qref) of the endothermic amount Q of the cooler 20 corresponding to the type of event is read (process 202).

Next, the pulling speed V is corrected according to the predicted change amount ΔQ with respect to the reference value Qref of the heat absorption amount Q of the cooler 20 (processing 203 to 205).

As in the first embodiment, the pulling speed V program, that is, the base value Vpg and the pulling speed correction amount Vq are stored in association with the length (axial position) of the silicon single crystal 10. (FIGS. 6A and 6B).

Accordingly, the pulling speed correction amount Vq corresponding to the predicted change ΔQ (= Q−Qref) with respect to the reference value Qref of the endothermic amount Q of the cooler 20 is read (processing 203), and the pulling speed V program, that is, the base value Vpg. Is read (process 204). Then, both are added to obtain a corrected pulling speed V (= Vpg + Vq). The corrected pulling speed V is stored in the storage device in association with the length (axial position) of the silicon single crystal 10 as a program of the corrected pulling speed V (FIG. 6C).

For this reason, after the occurrence of the event, the pulling speed V of the pulling shaft 4a of the pulling mechanism 4 is adjusted using the program of the corrected pulling speed V, and the silicon single crystal 10 is pulled up. That is, the corrected pulling speed V (= Vpg + Vq) corresponding to the current length (axial position) of the silicon single crystal 10 is read out, and the pulling shaft 4a of the pulling mechanism 4 is obtained so that this corrected pulling speed V is obtained. The pulling speed V is adjusted, and the silicon single crystal 10 is pulled (process 205).

In the second embodiment, similarly to the first embodiment, when the predicted change amount ΔQ of the endothermic amount Q of the cooler 20 is less than 4% of the reference value Q, the pulling speed V is not corrected, and the same When the predicted change amount ΔQ is 4% or more of the reference value Q, the pulling speed V is corrected to change from the base value Vpg by 0.01 mm / min or more, and the silicon single crystal 10 is pulled up.

In this embodiment, it is assumed that each process is automatically performed. However, each process including the creation of a program may be performed manually or a part of each process may be performed manually. It is.
As described above, according to the second embodiment, the relationship between the change amount (ΔQ) when the ability to cool the silicon single crystal 10 by the cooler 20 changes and the correction amount (Vq) of the pulling speed V is clarified. On the basis of the relationship, the pulling speed V is corrected according to the predicted change amount, so that the defect-free silicon single crystal 10 can be stably manufactured with good reproducibility by a simple method.

(Third embodiment)
In the first embodiment described above, the pulling speed V is corrected when the endothermic amount Q of the cooler 20 changes from the reference value Qref during pulling of the silicon single crystal 10. However, when the endothermic amount Q of the cooler 20 changes during the pulling of the silicon single crystal 10, the position P of the cooler 20 may be corrected so that the change is eliminated and the reference value Qref is restored.

FIG. 8 shows a control block diagram of the third embodiment.

As shown in FIG. 8, this control measures the endothermic amount Q of the cooler 20, and only the elevation distance Pq of the cooler 20 corresponding to the difference ΔQ between the measured value Q of the endothermic amount Q of the cooler 20 and the reference value Qref. The position P of the cooler 20 is corrected and the silicon single crystal 10 is pulled up.

It is assumed that the specific heat c of water, the reference value Qref of the heat absorption amount Q of the cooler 20, the cooler position program Ppg, and the cooler position correction amount Pq are stored in advance in the storage device.

That is, the inlet side cooling water temperature Tin is measured by the temperature measurement sensor 31 (process 301), the outlet side cooling water temperature Tout is measured by the temperature measurement sensor 32 (process 302), and the inlet side cooling water temperature is calculated from the outlet side cooling water temperature Tout. By subtracting Tin, Tout-Tin is obtained (processing 303). On the other hand, the coolant flow rate f is measured by the flow meter 33 (process 304).

  Then, the specific heat c of the water is read from the storage device, and based on the specific heat c of the water, Tout−Tin determined as described above, and the flow rate f of the cooling water, the above equation (1) (Q = ( (Tout−Tin) × f × c) is performed, and the heat absorption amount Q (kW) of the cooler 20 is obtained (processing 305).

The reference value Qref of the heat absorption amount Q of the cooler 20 is read from the storage device (process 306), the reference value Qref is subtracted from the current heat absorption amount Q of the cooler 20 measured as described above, and the heat absorption amount Q of the cooler 20 is obtained. A change amount ΔQ (= Q−Qref) with respect to the reference value Qref is obtained (processing 307).

Next, the position P of the cooler 20 is corrected according to the change amount ΔQ of the endothermic amount Q of the cooler 20 with respect to the reference value Qref (processing 308 to 311).

The cooler position program Ppg is set in advance as a reference position Ppg of the cooler 20 under manufacturing conditions that can manufacture the defect-free silicon single crystal 10. The cooler position program, that is, the reference position Ppg of the cooler 20 may be set in correspondence with the length (axial position) of the silicon single crystal 10 as in FIG.

FIG. 9 shows the relationship between the elevating distance Pq of the cooler 20 and the amount of change in the endothermic amount Q of the cooler 20 in order to set the endothermic amount Q of the cooler 20 to the reference value Qref. In FIG. 9, the reference position of the cooler 20 is set to zero.

As shown in FIG. 9, the endothermic amount Q of the cooler 20 increases as the position P of the cooler 20 decreases, and the endothermic amount Q of the cooler 20 decreases as the position P of the cooler 20 increases.

Therefore, based on the relationship shown in FIG. 9, the raising / lowering amount (cooler position correction amount) Pq of the cooler 20 corresponding to the change amount ΔQ (= Q−Qref) of the endothermic amount Q of the cooler 20 with respect to the reference value Qref is read ( Process 308), the cooler position program, that is, the reference position Ppg of the cooler 20 is read (process 309). Then, both are added (process 310), and a corrected cooler position P (= Ppg + Pq) is obtained. That is, when the amount of change ΔQ (= Q−Qref) of the endothermic amount Q of the cooler 20 with respect to the reference value Qref is positive, that is, when the measured endothermic amount Q is increased from the reference value Qref, the cooler reference position When the position P of the cooler 20 is corrected so that the cooler 20 rises from Ppg and the change amount ΔQ (= Q−Qref) is negative, that is, when the measured endothermic amount Q is reduced from the reference value Qref. The position P of the cooler 20 is corrected so that the cooler 20 descends from the cooler reference position Ppg (process 311).

The silicon single crystal 10 is pulled up at the corrected position P of the cooler 20.

In the third embodiment, as in the first embodiment, if the change amount ΔQ of the endothermic amount Q of the cooler 20 is less than 4% of the reference value Q, the position P of the cooler 20 is not corrected. When the change amount ΔQ is 4% or more of the reference value Q, the position P of the cooler 20 is corrected and the silicon single crystal 10 is pulled up.
As described above, according to the third embodiment, the relationship between the change amount (ΔQ) when the ability to cool the silicon single crystal 10 by the cooler 20 and the correction amount (Pq) of the cooler position P is clarified. Since the position P of the cooler 20 is corrected based on these relationships, the defect-free silicon single crystal 10 can be stably manufactured with good reproducibility by a simple method.

(Fourth embodiment)
In the third embodiment described above, the position P of the cooler 20 is corrected by capturing the change in the endothermic amount Q of the cooler 20 during the pulling of the silicon single crystal 10. However, when an event occurs in which the heat absorption amount Q of the cooler 20 changes, it is possible to predict the change in the heat absorption amount Q of the cooler 20 and correct the position P of the cooler 20.

FIG. 10 shows a control block diagram of the second embodiment.

As shown in FIG. 10, this control predicts the change ΔQ with respect to the reference value Qref of the endothermic amount Q of the cooler 20 when an event in which the endothermic amount Q of the cooler 20 changes occurs. A cooler position correction amount Pq corresponding to the change amount ΔQ is obtained, the reference position Ppg of the cooler 20 is corrected by the cooler position correction amount Pq, and the silicon single crystal 10 is pulled up at the corrected cooler position P. Is. It is assumed that the predicted change amount ΔQ of the endothermic amount Q of the cooler 20 for each event, the cooler position program, and the cooler position correction amount Pq are stored in advance in the storage device.

The occurrence of an event is automatically detected, and a signal indicating the type of event and the occurrence of the event is output. Alternatively, when an event occurs, the operator manually operates the operation panel to output a signal indicating the type of event and the occurrence of the event (process 401).

Next, the predicted change amount ΔQ (= Q−Qref) of the endothermic amount Q of the cooler 20 corresponding to the type of event is read (processing 402).

Next, the position P of the cooler 20 is corrected according to the predicted change amount ΔQ with respect to the reference value Qref of the heat absorption amount Q of the cooler 20 (processing 403 to 405).

As in the third embodiment, the cooler position program, that is, the reference position Ppg of the cooler 20 is set, and the cooler position correction amount (cooler lift amount) Pq is associated with the amount of change in the endothermic amount Q of the cooler 20. Is stored (FIG. 9).

Therefore, the cooler position correction amount Pq corresponding to the predicted change amount ΔQ (= Q−Qref) with respect to the reference value Qref of the heat absorption amount Q of the cooler 20 is read (processing 403), and the program of the cooler position, that is, the reference of the cooler 20 The position Ppg is read (process 404). And both are added and the correct | amended cooler position P (= Ppg + Pq) is calculated | required. The corrected cooler position P is stored in the storage device as a program of the corrected cooler position P.

For this reason, after the event occurs, the position P of the cooler 20 is adjusted using the program of the corrected cooler position P, and the silicon single crystal 10 is pulled up. That is, the corrected cooler position P (= Ppg + Pq) is read out, the cooler 20 is moved up and down to the corrected cooler position P, and then the silicon single crystal 10 is pulled up (process 405).

In the fourth embodiment, as in the first embodiment, the position P of the cooler 20 is not corrected if the predicted change ΔQ of the heat absorption amount Q of the cooler 20 is less than 4% of the reference value Q. When the predicted change amount ΔQ is 4% or more of the reference value Q, the position P of the cooler 20 is corrected and the silicon single crystal 10 is pulled up.

In this embodiment, it is assumed that each process is automatically performed. However, each process including the creation of a program may be performed manually or a part of each process may be performed manually. It is.
As described above, according to the fourth embodiment, the relationship between the change amount (ΔQ) when the ability to cool the silicon single crystal 10 by the cooler 20 changes and the cooler position correction amount (Pq) is clarified. Based on the relationship, the cooler position P is corrected in accordance with the predicted change amount, so that the defect-free silicon single crystal 10 can be stably manufactured with good reproducibility by a simple method.

(5th Example)
In the first embodiment described above, the pulling speed V is corrected when the endothermic amount Q of the cooler 20 changes from the reference value Qref during pulling of the silicon single crystal 10. However, when the endothermic amount Q of the cooler 20 changes during the pulling of the silicon single crystal 10, the distance D from the lower end of the heat shielding plate 8 to the melt 5 is corrected so that the change is eliminated and the reference value Qref is restored. May be.

FIG. 11 shows a control block diagram of the fifth embodiment.

As shown in FIG. 8, this control measures the endothermic amount Q of the cooler 20, and only the distance Dq corresponding to the difference .DELTA.Q between the measured value Q of the endothermic amount Q of the cooler 20 and the reference value Qref. The distance D from the lower end to the melt 5 is corrected, and the silicon single crystal 10 is pulled up.

The specific heat c of water, the reference value Qref of the heat absorption amount Q of the cooler 20, the program Dpg of the distance D from the lower end of the heat shielding plate 8 to the melt 5, and the correction amount Dq of the distance D are stored in advance in the storage device. It shall be left.

That is, the inlet-side cooling water temperature Tin is measured by the temperature measurement sensor 31 (process 501), the outlet-side cooling water temperature Tout is measured by the temperature measurement sensor 32 (process 502), and the inlet-side cooling water temperature is calculated from the outlet-side cooling water temperature Tout. Tin is subtracted to obtain Tout-Tin (process 503). On the other hand, the coolant flow rate f is measured by the flow meter 33 (process 504).

  Then, the specific heat c of the water is read from the storage device, and based on the specific heat c of the water, Tout−Tin determined as described above, and the flow rate f of the cooling water, the above equation (1) (Q = ( (Tout−Tin) × f × c) is performed, and the heat absorption amount Q (kW) of the cooler 20 is obtained (processing 505).

The reference value Qref of the heat absorption amount Q of the cooler 20 is read from the storage device (process 506), the reference value Qref is subtracted from the current heat absorption amount Q of the cooler 20 measured as described above, and the heat absorption amount Q of the cooler 20 is obtained. A change amount ΔQ (= Q−Qref) with respect to the reference value Qref is obtained (processing 507).

Next, the distance D from the lower end of the heat shielding plate 8 to the melt 5 (hereinafter simply referred to as “distance D” as appropriate) is corrected in accordance with the amount of change ΔQ of the endothermic amount Q of the cooler 20 with respect to the reference value Qref. (Processes 508 to 511).

The distance D program Dpg is set in advance as a reference distance Dpg under manufacturing conditions capable of manufacturing a defect-free silicon single crystal 10. The distance D program, that is, the reference distance Dpg may be set corresponding to the length (axial position) of the silicon single crystal 10 as in FIG.

FIG. 13 shows the relationship between the distance correction amount Dq for making the heat absorption amount Q of the cooler 20 the reference value Qref and the amount of change in the heat absorption amount Q of the cooler 20 (endothermic amount increase rate (%)). . In FIG. 13, the reference position for the distance D is set to zero.

13 and the relationship shown in FIG. 12 and as described above with reference to FIG. 4, when the endothermic amount Q of the cooler 20 decreases, the pulling speed V at which the defect-free silicon single crystal 10 can be manufactured decreases. It can be determined based on the relationship.

That is, FIG. 12 shows the relationship between the amount of change in the distance D from the lower end of the heat shielding plate 8 to the melt 5 and the amount of change in the pulling rate V that can produce the defect-free silicon single crystal 10. Yes. As shown in FIG. 12, there is a relationship in which the pulling speed V at which the defect-free silicon single crystal 10 can be manufactured decreases as the distance D increases. On the other hand, as described above with reference to FIG. 4, when the endothermic amount Q of the cooler 20 decreases, there is a relationship that the pulling speed V at which the defect-free silicon single crystal 10 can be manufactured decreases. Therefore, the correspondence shown in FIG. 13 is obtained based on both of these relationships.

Therefore, based on the relationship shown in FIG. 13, the correction amount Dq of the distance D corresponding to the change amount ΔQ (= Q−Qref) of the endothermic amount Q of the cooler 20 with respect to the reference value Qref is read (processing 508), and the distance D The program, that is, the reference distance Dpg is read (process 509). Then, both are added (process 510), and a corrected distance D (= Dpg + Dq) is obtained. That is, when the change amount ΔQ (= Q−Qref) of the endothermic amount Q of the cooler 20 with respect to the reference value Qref is positive, that is, when the measured endothermic amount Q is increased from the reference value Qref, the reference distance Dpg. If the distance D is corrected so that the distance D increases from the distance D and the change ΔQ (= Q−Qref) is negative, that is, if the measured endothermic amount Q is reduced from the reference value Qref, the reference distance Dpg is used. The distance D is corrected so that the distance D is reduced (process 511).

Then, the silicon single crystal 10 is pulled at the corrected distance D.

In the fifth embodiment, as in the first embodiment, if the change amount ΔQ of the endothermic amount Q of the cooler 20 is less than 4% of the reference value Q, the distance D is not corrected and the change amount is the same. When ΔQ is 4% or more of the reference value Q, the distance D is corrected and the silicon single crystal 10 is pulled up.
As described above, according to the fifth embodiment, the amount of change (ΔQ) when the ability to cool the silicon single crystal 10 by the cooler 20 changes, and the distance D from the lower end of the heat shielding plate 8 to the melt 5. Since the relationship with the correction amount (Dq) is clarified and the distance D is corrected based on these relationships, the defect-free silicon single crystal 10 can be stably produced with good reproducibility.

(Sixth embodiment)
In the fifth embodiment described above, the distance D from the lower end of the heat shielding plate 8 to the melt 5 is corrected by capturing the change in the heat absorption amount Q of the cooler 20 during the pulling of the silicon single crystal 10. However, when an event in which the heat absorption amount Q of the cooler 20 changes occurs, it is possible to predict the change in the heat absorption amount Q of the cooler 20 and correct the distance D.

FIG. 14 shows a control block diagram of the sixth embodiment.

As shown in FIG. 14, this control predicts a change amount ΔQ with respect to the reference value Qref of the endothermic amount Q of the cooler 20 when an event in which the endothermic amount Q of the cooler 20 changes occurs. The distance correction amount Dq corresponding to the change amount ΔQ is obtained, the reference distance Dpg is corrected by the distance correction amount Dq, and the silicon single crystal 10 is pulled up by the corrected distance D. It is assumed that the predicted change amount ΔQ of the endothermic amount Q of the cooler 20 for each event, the distance D program, and the correction amount Dq of the distance D are stored in advance in the storage device.

The occurrence of an event is automatically detected, and a signal indicating the type of event and the occurrence of the event is output. Alternatively, when an event occurs, the operator manually operates the operation panel to output a signal indicating the type of event and the occurrence of the event (process 601).

Next, the predicted change amount ΔQ (= Q−Qref) of the endothermic amount Q of the cooler 20 corresponding to the type of event is read (process 602).

Next, the distance D is corrected according to the predicted change amount ΔQ with respect to the reference value Qref of the endothermic amount Q of the cooler 20 (processing 603 to 605).

Similarly to the fifth embodiment, the distance D program, that is, the reference distance Dpg is set, and the distance correction amount Dq is stored in association with the amount of change in the endothermic amount Q of the cooler 20 (FIG. 13). ).

Therefore, the distance correction amount Dq corresponding to the predicted change amount ΔQ (= Q−Qref) with respect to the reference value Qref of the heat absorption amount Q of the cooler 20 is read (process 603), and the program of the distance D, that is, the reference distance Dpg is read. (Process 604). Then, both are added to obtain a corrected distance D (= Dpg + Dq). The corrected distance D is stored in the storage device as a program for the corrected distance D.

For this reason, after the occurrence of the event, the distance D is adjusted using the program of the correction distance D, and the silicon single crystal 10 is pulled up. That is, the correction distance D (= Dpg + Dq) is read out, and the vertical position of the quartz crucible 3 or the vertical position of the heat shielding plate 8 is adjusted so that the correction distance D is obtained. It is pulled up (process 605).

In the sixth embodiment, as in the first embodiment, if the predicted change amount ΔQ of the heat absorption amount Q of the cooler 20 is less than 4% of the reference value Q, the distance D is not corrected, and the same prediction is made. When the change amount ΔQ is 4% or more of the reference value Q, the distance D is corrected and the silicon single crystal 10 is pulled up.
In this embodiment, it is assumed that each process is automatically performed. However, each process including the creation of a program may be performed manually or a part of each process may be performed manually. It is.
As described above, according to the sixth embodiment, the amount of change (ΔQ) when the ability to cool the silicon single crystal 10 by the cooler 20 changes, and the distance D from the lower end of the heat shielding plate 8 to the melt 5. Since the relationship with the correction amount (Dq) is clarified and the distance D is corrected according to the predicted change amount based on the relationship, the defect-free silicon single crystal 10 is stabilized with a simple method and with good reproducibility. Can be manufactured.

In the embodiment, the description has been made assuming a water-cooled cooler. However, any cooling medium may be used for the cooler, and the silicon single crystal 10 may be cooled by absorbing heat radiated from the silicon single crystal 10. Any heat exchanger can be used.

FIG. 1 is a diagram schematically showing a configuration of a single crystal pulling apparatus according to an embodiment. FIG. 2 is a configuration diagram of a cooling water circuit of the water cooling type cooler used in the embodiment. FIG. 3 is a diagram showing the relationship between the axial position of the silicon single crystal and the endothermic amount of the cooler for each ingot number. FIG. 4A shows the relationship between the axial position of the silicon single crystal and the amount of change with respect to the base value of the pulling rate, NO. 1, NO. 2, NO. 3, NO. 4, NO. 5 is a diagram showing each ingot of No. 5 and FIG. 4B shows the relationship between the axial position of the silicon single crystal and the amount of change with respect to the base value of the pulling speed V. 6, NO. 7, NO. It is the figure shown for every 8 ingots. FIG. 5 is a control block diagram of the first embodiment. FIG. 6A is a diagram showing a program of the pulling speed V, that is, a base value corresponding to the length (axial position) of the silicon single crystal, and FIG. FIG. 6C is a diagram showing the length of the single crystal corresponding to the length (axial position). FIG. 6C shows the corrected pulling speed corresponding to the length of the silicon single crystal (axial position). FIG. FIG. 7 is a control block diagram of the second embodiment. FIG. 8 is a control block diagram of the third embodiment. FIG. 9 is a diagram showing a correspondence relationship between the cooler descending distance and the amount of change in the endothermic amount of the cooler. FIG. 10 is a control block diagram of the fourth embodiment. FIG. 11 is a control block diagram of the fifth embodiment. FIG. 12 is a diagram showing the relationship between the amount of change in the distance from the lower end of the heat shield plate to the melt and the amount of change in the pulling rate at which a defect-free silicon single crystal can be produced. FIG. 13 is a diagram showing the relationship between the distance correction amount for making the endothermic amount of the cooler a reference value and the amount of change in the endothermic amount of the cooler (endothermic amount increase rate (%)). FIG. 14 is a control block diagram of the sixth embodiment.

Explanation of symbols

  1 silicon single crystal manufacturing equipment, 2 CZ furnace, 10 silicon single crystal, 20 cooler

Claims (14)

In a method for manufacturing a semiconductor single crystal, a cooler is disposed around a semiconductor single crystal pulled from a melt, and the semiconductor single crystal is pulled and grown while cooling the semiconductor single crystal by the cooler.
While presetting the reference value of the endothermic amount of the cooler and the base value of the pulling rate under the production conditions capable of producing a defect-free semiconductor single crystal,
In order to produce a defect-free semiconductor single crystal, the relationship between the amount of change with respect to the reference value of the endothermic amount of the cooler and the amount of change with respect to the base value of the pulling speed is set in advance,
Measure the heat absorption of the cooler,
The amount of change in the pulling speed corresponding to the difference between the measured value of the endothermic amount of the cooler and the reference value is obtained based on the above relationship,
A method of manufacturing a semiconductor single crystal, wherein the semiconductor single crystal is pulled up by correcting the pulling rate by the calculated change amount. 2. The semiconductor single crystal according to claim 1, wherein when the difference between the measured value of the endothermic amount of the cooler and the reference value is 4% or more of the reference value, the pulling rate is corrected to pull up the semiconductor single crystal. A method for producing a single crystal. When the difference between the measured value of the endothermic amount of the cooler and the reference value is 4% or more of the reference value, the pulling speed is corrected by a change amount of 0.01 mm / min or more, and the semiconductor single crystal is pulled up. The method for producing a semiconductor single crystal according to claim 1. In a method for manufacturing a semiconductor single crystal, a cooler is disposed around a semiconductor single crystal pulled from a melt, and the semiconductor single crystal is pulled and grown while cooling the semiconductor single crystal by the cooler.
While presetting the reference value of the endothermic amount of the cooler and the base value of the pulling rate under the production conditions capable of producing a defect-free semiconductor single crystal,
In order to produce a defect-free semiconductor single crystal, the relationship between the amount of change with respect to the reference value of the endothermic amount of the cooler and the amount of change with respect to the base value of the pulling speed is set in advance,
When an event that changes the endothermic amount of the cooler occurs, predict the amount of change of the endothermic amount of the cooler relative to the reference value,
The amount of change in the pulling speed corresponding to the predicted amount of change is obtained based on the relationship,
A method of manufacturing a semiconductor single crystal, wherein the semiconductor single crystal is pulled up by correcting the pulling rate by the calculated change amount. 5. The method for producing a semiconductor single crystal according to claim 4, wherein when the predicted change in the endothermic amount of the cooler is 4% or more of the reference value, the pulling rate is corrected and the semiconductor single crystal is pulled up. . The semiconductor single crystal is pulled up by correcting the pulling rate by a change amount of 0.01 mm / min or more when the predicted change amount of the endothermic amount of the cooler is 4% or more of the reference value. Item 5. A method for producing a semiconductor single crystal according to Item 4. In a method for manufacturing a semiconductor single crystal, a cooler is disposed so as to be movable up and down around a semiconductor single crystal pulled from a melt, and the semiconductor single crystal is pulled and grown while cooling the semiconductor single crystal with the cooler. ,
While presetting the reference value of the endothermic amount of the cooler and the reference position of the cooler under manufacturing conditions capable of producing a defect-free semiconductor single crystal,
In order to make the endothermic amount of the cooler a reference value, a relationship between the cooler elevating distance and the amount of change in the endothermic amount of the cooler is set in advance,
Measure the heat absorption of the cooler,
Based on the above relationship, calculate the cooler lift distance corresponding to the difference between the measured value of the heat absorption amount of the cooler and the reference value,
A method for producing a semiconductor single crystal, wherein the position of the cooler is corrected by the calculated elevation distance and the semiconductor single crystal is pulled up. The semiconductor single crystal is pulled up by correcting the position of the cooler when the difference between the measured value of the endothermic amount of the cooler and the reference value is 4% or more of the reference value. A method for producing a semiconductor single crystal. In a method for manufacturing a semiconductor single crystal, a cooler is disposed so as to be movable up and down around a semiconductor single crystal pulled from a melt, and the semiconductor single crystal is pulled and grown while cooling the semiconductor single crystal with the cooler. ,
While presetting the reference value of the endothermic amount of the cooler and the reference position of the cooler under manufacturing conditions capable of producing a defect-free semiconductor single crystal,
In order to make the endothermic amount of the cooler a reference value, a relationship between the cooler elevating distance and the amount of change in the endothermic amount of the cooler is set in advance,
When an event that changes the endothermic amount of the cooler occurs, predict the amount of change of the endothermic amount of the cooler relative to the reference value,
Based on the above relationship, the cooling distance of the cooler corresponding to the predicted change amount is obtained,
A method for producing a semiconductor single crystal, wherein the position of the cooler is corrected by the calculated elevation distance and the semiconductor single crystal is pulled up. 10. The semiconductor single crystal manufacturing method according to claim 9, wherein when the predicted change in the endothermic amount of the cooler is 4% or more of the reference value, the position of the cooler is corrected and the semiconductor single crystal is pulled up. Method. A semiconductor single crystal is manufactured by arranging a cooler around a semiconductor single crystal pulled from the melt and a heat shielding plate, and pulling and growing the semiconductor single crystal while cooling the semiconductor single crystal by the cooler. In the manufacturing method of
While preliminarily setting a reference value of the endothermic amount of the cooler under manufacturing conditions capable of manufacturing a defect-free semiconductor single crystal and a reference distance from the lower end of the heat shielding plate to the melt,
In order to set the endothermic amount of the cooler as a reference value, the relationship between the amount of correction of the distance from the lower end of the heat shield plate to the melt and the amount of change in the endothermic amount of the cooler is set in advance,
Measure the heat absorption of the cooler,
A distance correction amount from the lower end of the heat shield plate corresponding to the difference between the measured value of the endothermic amount of the cooler and the reference value is obtained based on the relationship,
A method of manufacturing a semiconductor single crystal, wherein the semiconductor single crystal is pulled up by correcting the distance from the lower end of the heat shielding plate to the melt by the calculated distance correction amount. When the difference between the measured value of the endothermic amount of the cooler and the reference value is 4% or more of the reference value, the distance from the bottom of the heat shield plate to the melt is corrected to pull up the semiconductor single crystal. The method for producing a semiconductor single crystal according to claim 11. A semiconductor single crystal is manufactured by arranging a cooler around a semiconductor single crystal pulled from the melt and a heat shielding plate, and pulling and growing the semiconductor single crystal while cooling the semiconductor single crystal by the cooler. In the manufacturing method of
While preliminarily setting a reference value of the endothermic amount of the cooler under manufacturing conditions capable of manufacturing a defect-free semiconductor single crystal and a reference distance from the lower end of the heat shielding plate to the melt,
In order to set the endothermic amount of the cooler as a reference value, the relationship between the amount of correction of the distance from the lower end of the heat shield plate to the melt and the amount of change in the endothermic amount of the cooler is set in advance,
When an event that changes the endothermic amount of the cooler occurs, predict the amount of change of the endothermic amount of the cooler relative to the reference value,
A distance correction amount from the lower end of the heat shield plate corresponding to the predicted change amount to the melt is determined based on the relationship,
A method of manufacturing a semiconductor single crystal, wherein the semiconductor single crystal is pulled up by correcting the distance from the lower end of the heat shielding plate to the melt by the calculated distance correction amount. The semiconductor single crystal is pulled up by correcting the distance from the lower end of the heat shielding plate to the melt when the predicted change in the endothermic amount of the cooler is 4% or more of the reference value. The manufacturing method of the semiconductor single crystal of description.

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