JP2007284324A - Manufacturing device and manufacturing method for semiconductor single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing device and a manufacturing method for a semiconductor single crystal by which a silicon single crystal having a desired defect region or a desired defect-free region can be easily manufactured in high yield. <P>SOLUTION: The manufacturing device for a semiconductor single crystal is equipped with: a heat treatment furnace 10 to heat treat a silicon single crystal pulled by using a single crystal pulling device which grows the silicon single crystal while pulling from a silicon melt housed in a crucible; and a control means 11 to control the temperature in the heat treatment furnace 10. The control means 11 carries out first control of controlling the heat treatment furnace 10 rendering the silicon single crystal into a defect reset temperature, and a second control of controlling a temperature gradient in a first direction in the heat treatment furnace with respect to a heat treatment time so as to impart a temperature hysteresis to the silicon single crystal upon growing the silicon single crystal having a desired defect region or defect-free region from the silicon melt. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor single crystal manufacturing apparatus and manufacturing method, and more particularly, to a technique capable of growing a crystal diameter to a desired value and then performing defect control in the crystal after the single crystal growth.

  As a method for growing a silicon single crystal, there are methods called an FZ method and a Czochralski method (CZ method). In the silicon single crystal grown by the CZ method, a defect called a Grown-in defect is formed during crystal growth, and is detected when the silicon single crystal obtained after the crystal growth is evaluated.

FIG. 4 is a defect distribution diagram in a longitudinal section of a silicon single crystal grown while gradually decreasing the pulling rate. As shown in FIG. 4, the region where R-OSF (Ring-Oxidation induced Stacking Fault) appears shrinks inward from the outer peripheral side of the crystal as the pulling rate is reduced. Further, a grown-in defect observed after crystal growth differs between a crystal pulled at a higher speed than the R-OSF and a crystal pulled at a lower speed. In the high-speed pulled crystal, a void defect (a void type defect) called COP (crystal originated particle) or FPD (flow pattern defect) is detected. In the slow pulling crystal, interstitial Si aggregates accompanied by dislocations are generated, and interstitial Si defects (dislocation cluster defects) are detected. Further, there is a defect-free region in which no grown-in defect is detected between the R-OSF and the interstitial Si defect region.
The void defect in the silicon single crystal is a deterioration factor of the initial oxide film breakdown voltage characteristic of the wafer. In addition, interstitial Si defects in the silicon single crystal also degrade device characteristics. Therefore, crystal growth in a defect-free region is desired because of the quality characteristics of the silicon single crystal.

These Grown-in defects are the ratio of the pulling rate V (mm / min) when growing a silicon single crystal to the crystal temperature gradient G (° C./mm) in the pulling axis direction near the solid-liquid interface. The amount of introduction is considered to be determined by the G (mm ² / ° C./min) value.
The meaning of the V / G value indicates the balance between the advection of vacancies according to the pulling rate and the diffusion of interstitial Si according to the temperature gradient. That is, when the V / G value is large, the advection according to the vacancy pulling speed exceeds the diffusion of interstitial Si according to the temperature gradient, and the vacancy concentration becomes high. Vacancy-type defects occur when vacancy supersaturation occurs due to a temperature drop accompanying the progress of pulling of the silicon single crystal. On the contrary, when the V / G value is small, the advection according to the vacancy pulling speed is lower than the diffusion of the interstitial Si according to the temperature gradient, and the interstitial Si concentration becomes relatively high. Furthermore, interstitial Si supersaturation occurs due to the temperature drop accompanying the progress of pulling of the silicon single crystal, and interstitial Si defects are generated.

That is, it is possible to manufacture a silicon single crystal having a desired defect region or a desired defect-free region by growing the silicon single crystal while keeping the V / G value constant at a predetermined value. For this reason, conventionally, the growth axis direction during the pulling of the single crystal is such that the pulling speed margin that can be pulled so that the entire surface in the radial direction of the silicon single crystal becomes a defect-free region is always greater than or equal to a predetermined value. Has proposed a manufacturing method for changing the pulling condition (see, for example, Patent Document 1).
JP 2005-15296 A

  However, in the above-described conventional technology, in order to manufacture a silicon single crystal in which the entire surface in the radial direction of the silicon single crystal is a defect-free region, the single crystal is controlled while controlling the V / G value to be constant at a predetermined value. Therefore, there are problems shown below, and the production yield is low.

1. The pulling speed is a control parameter for the dimension in the crystal diameter direction (crystal diameter) at the time of pulling the single crystal, in addition to the side surface as a parameter that determines the state of crystal defects as the V / G value. Therefore, in order to control the diameter of the silicon single crystal, it is necessary to change the pulling speed, and the V / G value may deviate from the range where there is no defect.
2. During the growth of the silicon single crystal, when the transition from the shoulder formation of the silicon single crystal to the formation of the straight body portion, a sudden change in the crystal temperature gradient G and the pulling rate V occurs, and the crystal temperature gradient G and the pulling rate V are stable. Until then, the process had to proceed considerably, and it was difficult to make defect-free crystals on the TOP side of the straight body. For this reason, there is a problem that a considerable part of the raised straight body portion cannot be a product having a desired quality.
3. In order to eliminate defects throughout the entire crystal plane, it is necessary to make the V / G value uniform in the plane. Therefore, it is necessary to make the crystal temperature gradient G uniform in the crystal plane. However, since the thermal environment in the furnace changes as the silicon single crystal is pulled up, it is extremely difficult to always make the in-plane crystal temperature gradient uniform during the pulling of the silicon single crystal. That is, there has been a demand for a method for producing a single crystal with high production efficiency by reducing the control parameters for crystal pulling as much as possible.
4). Each time the silicon single crystal is pulled up due to deterioration of the heat insulating material in the hot zone or change in the emissivity of the inner wall surface of the chamber, the thermal environment changes slightly and the crystal temperature gradient G changes. For this reason, since it originally became defect-free only in a narrow V / G value range, even if a crystal was produced under exactly the same process conditions as before, it was often not a defect-free crystal. That is, there is a possibility that the yield may be deteriorated, and there is a demand for improving these.

  The present invention has been made in view of the above circumstances, and a semiconductor single crystal manufacturing apparatus and manufacturing capable of easily manufacturing a semiconductor single crystal such as a silicon single crystal having a desired defect region or a desired defect-free region with a high yield. The aim is to realize the method.

In order to solve the above problems, the present inventor has intensively studied and, as will be described below, invented a method for producing a semiconductor single crystal that facilitates the control of the V / G value during production and improves the yield. did.
Specifically, in the semiconductor single crystal manufacturing apparatus of the present invention, a semiconductor single crystal manufacturing apparatus for controlling Grown-in defect inside the semiconductor single crystal,
Reset heating means for heating and maintaining the single crystal at a thermal history reset temperature for resetting a thermal history at the time of crystal production that affects a Grown-in defect state inside the single crystal;
A thermal history reapplying means for lowering the single crystal from the thermal history reset temperature and reapplying a thermal history that makes the grown-in defect state a desired state;
By solving this problem, the above-mentioned problems were solved.
In the present invention, the reset heating means and the heat history re-applying means are the same heating means,
When the semiconductor single crystal is continuously cooled from the thermal history reset temperature by controlling this heating means, a desired thermal history that affects the grown-in defect state inside the single crystal is reapplied. It is preferable that a control means for controlling the heat treatment temperature and the temperature lowering rate is provided.
The present invention relates to a heat treatment furnace for performing Grown-in defect control in the semiconductor single crystal,
The heating means for overheating the heat treatment furnace;
Control means for controlling the temperature in the heat treatment furnace by the heating means,
The control means controls the temperature in the heat treatment furnace so that the single crystal is heated and maintained at a thermal history reset temperature for resetting a thermal history at the time of crystal production that affects a grown-in defect state inside the single crystal. Heat history reset control,
After the thermal history reset control, the temperature gradient and the temperature lowering rate of the single crystal are controlled so that the single crystal is lowered from the thermal history reset temperature to re-apply a thermal history that makes the crystal state a desired state. It is preferable to perform heat history re-assignment control.
The present invention relates to a heat treatment furnace for performing crystal state control that contributes to Grown-in defects in the semiconductor single crystal,
The heating means for overheating the heat treatment furnace;
Control means for controlling the temperature in the heat treatment furnace by the heating means,
The control means controls the temperature of the heat treatment furnace so that the single crystal is heated and maintained at a thermal history reset temperature for resetting a thermal history at the time of crystal production that affects a grown-in defect state inside the single crystal. Thermal history reset control,
After the thermal history reset control, a temperature gradient in a first direction in the heat treatment furnace is provided so as to re-apply a thermal history that lowers the single crystal from the thermal history reset temperature and makes the crystal state a desired state. It is preferable to perform heat history reapplying control for controlling the temperature drop rate.
In the present invention, the temperature gradient in the heat treatment furnace and the temperature drop rate are such that the crystal temperature gradient G in the pulling axis direction in the vicinity of the solid-liquid interface when the semiconductor single crystal is pulled using a single crystal pulling apparatus (° C./mm ) And the pulling speed V (mm / min), it is preferable to re-apply the heat history so that the ratio V / G (mm ² / ° C. min) is within a predetermined range. .
In the present invention, it is preferable that the heat treatment furnace performs heat history resetting and re-applying heat treatment on a semiconductor single crystal ingot obtained by dividing the semiconductor single crystal in the axial direction.
In the present invention, it is preferable that the heat treatment furnace supports a plurality of the semiconductor single crystal ingots at the same time so that the thermal history can be reset and reapplied.
The method for producing a semiconductor single crystal according to the present invention is a method for producing a semiconductor single crystal for controlling a Grown-in defect inside the semiconductor single crystal,
A reset heating step of heating and maintaining the single crystal at a thermal history reset temperature for resetting a thermal history at the time of crystal production that affects a grown-in defect state inside the single crystal;
A thermal history reapplying step of lowering the single crystal from the thermal history reset temperature to reapply a thermal history that makes the Grown-in defect state a desired state;
By solving this problem, the above-mentioned problems were solved.
In the present invention, it is preferable that the reset heating process and the thermal history re-applying process are continuously performed.
In the thermal history re-applying step, the present invention provides a temperature gradient of the single crystal so as to re-apply a thermal history that lowers the single crystal from the thermal history reset temperature and makes the crystalline state a desired state. It is preferable to control the cooling rate.
In the heat history reapplying step, the present invention provides a heat history re-applying process in which the single crystal is lowered from the heat history reset temperature to reapply a heat history that makes the grown-in defect state a desired state. It is preferable to control the temperature gradient in the first direction and the cooling rate.
In the present invention, the temperature gradient and the temperature lowering rate are the same as the pulling rate V (mm / min) when pulling up the semiconductor single crystal using a single crystal pulling apparatus and the crystal temperature gradient G in the pulling axis direction near the solid-liquid interface. Corresponding to (° C./mm), it is preferable to re-apply the thermal history so that the V / G (mm ² / ° C. min) value as a ratio thereof falls within a predetermined range.
The present invention preferably includes a slicing step of separating the semiconductor single crystal in the axial direction into a semiconductor single crystal ingot before the reset heating step.
In the present invention, the reset heating step and the heat treatment re-application step can be simultaneously performed on the plurality of single crystal ingots.

In the method for producing a semiconductor single crystal according to the present invention, for controlling a grown-in defect inside the semiconductor single crystal with respect to the semiconductor single crystal produced with a desired diameter by the CZ method, the FZ method, or other methods. A method for manufacturing a semiconductor single crystal, which is maintained at a temperature near the melting point of the semiconductor after the single crystal is manufactured by pulling up by the CZ method, etc., so that the crystal state contributes to the grown-in defects inside the single crystal. A reset heating step of heating and maintaining the single crystal at a thermal history reset temperature for resetting the thermal history at the time of producing the crystal to affect, and lowering the single crystal from the thermal history reset temperature to bring the crystal state into a desired state A heat history reapplying step for reapplying a heat history to achieve a desirable crystal state as shown below. Can.
That is, in the method for producing a semiconductor single crystal according to the present invention, the heat history at the time of crystal production that affects the grown-in defect state in the single crystal, that is, the silicon single crystal can be obtained at the time of crystal production by pulling up the CZ method. For example, without worrying about the distribution of vacancies and interstitial silicon, the diffusion rate of each, and the state of pair annihilation, for example, a single crystal can be formed at a pulling rate with a diameter set so that the production efficiency is the highest. Can be raised. Then, after the pulling, the thermal history applied to the single crystal at the time of pulling (manufacturing) is used as a reset heating process by a method such as heating history of the single crystal near the melting point reset temperature, that is, near the melting point. Speaking of a single crystal, the grown-in defects such as vacancy, interstitial silicon distribution, void defects, oxygen precipitates, etc. are reset, that is, in the CZ method, so to speak, the solidified state close to the melt. That is, it returns to a state in which no crystal state is determined. Furthermore, as the heat history re-applying step, the temperature state that gives the single crystal the most preferable heat history at the time of pulling in the CZ method is reproduced. By lowering the temperature of the crystal, the thermal history that affects the crystal state contributing to the grown-in defects in the single crystal is made the most preferable state, and this thermal history is reapplied without worrying about the pulling rate in the CZ method. A desired crystal state, such as a distribution state of vacancies and interstitial silicon, can be realized only by the process. As a result, it becomes possible to easily manufacture defect-free silicon single crystals and the like that have been conventionally required to control conditions such as the pulling speed within an extremely narrow range with high production efficiency. Thus, in the present invention, a semiconductor single crystal manufacturing apparatus for controlling a grown-in defect state inside a semiconductor single crystal, the reset heating means for heating and maintaining the single crystal at the thermal history reset temperature And a thermal history reapplying means for reapplying a thermal history that lowers the single crystal from the thermal history reset temperature to bring the crystalline state into a desired state. It has been realized.

  In the present invention, the reset heating unit and the thermal history re-applying unit are the same heating unit, and when the semiconductor single crystal is cooled continuously from the thermal history reset temperature by controlling the heating unit. Provided with a control means for controlling a heat treatment temperature and a temperature lowering rate so as to re-apply a desired thermal history to the grown-in defects inside the single crystal, thereby the reset heating step and the thermal history. The re-application process can be performed continuously. As a result, it is possible to freely set the Grown-in defect state inside the single crystal regardless of the temperature state in the single crystal manufactured by pulling, and thus a single crystal in a desired state such as a defect-free single crystal can be set. Crystals can be easily manufactured at a high yield. Here, the temperature state in the single crystal produced by pulling is that the highest temperature in the pulling furnace is the melt, and the height position of the pulling single crystal goes upward through the solid-liquid interface (melt This means a temperature state that includes a state in which the temperature decreases as the distance from the object increases, and the positional relationship of such a temperature state, but the present invention does not care about these, and the thermal history in the single crystal. Can be controlled and reassigned.

According to the present invention, in the thermal history reapplying step, the single crystal is reapplied so that the single crystal is lowered from the thermal history reset temperature to reapply a thermal history that makes the Grown-in defect state a desired state. By controlling the temperature gradient and the temperature lowering rate, for example, unlike the temperature state in the pulling furnace, it is possible to take measures such as lowering the temperature of the entire single crystal while forming a temperature gradient in the radial direction of the single crystal. . In addition to providing a temperature gradient in the crystal axis direction in this way, it is possible to crystallize defect-free by giving a temperature gradient in the radial direction, and other directions such as a temperature gradient oblique to the crystal axis are also possible. It is possible to lower the temperature of the entire single crystal while forming a temperature gradient in an arbitrary direction.
Furthermore, the single crystal is processed so that the heat history with respect to the temperature change can be set as equal as possible in both the radial direction and the axial direction so that the diameter dimension and the axial dimension are substantially equal, and as it is from the outside of the single crystal. By cooling, it is possible to adopt means for lowering the temperature while forming a temperature gradient in a state close to point symmetry.
Further, at this time, the single crystal is shaped so that the difference from the point to the surface centering around the center of gravity as well as the axial direction and the radial direction is as small as possible in almost all directions. By processing, that is, making the shape as close to a sphere as possible, or making the surface area as small as possible with the same volume, while forming a temperature gradient in a point-symmetric state when cooled from the outside of the single crystal as it is It is also possible to lower the temperature and make the Grow-in defect state distribution inside the single crystal symmetric.
As a result, it is possible to control various types of grown-in defect states without worrying about restrictions on the temperature state position such as the relationship between the melt and the hot zone. At this time, it is important to determine the temperature gradient and the cooling rate in the single crystal so as to correspond to the value of V / G at the time of pulling.

In the heat history reapplying step, the present invention provides a first direction in the heat treatment furnace so as to reapply a heat history that lowers the single crystal from the heat history reset temperature and makes the crystal state a desired state. By controlling the temperature gradient and the temperature lowering rate, the thermal history can be reapplied to the single crystal by reproducing the temperature state in the pulling furnace, for example, with the first direction being vertically upward. Thereby, the above-mentioned desired thermal history can be given to the single crystal by using the enormous pulling data accumulated so far. That is, in other words, in the thermal history reapplying step, a temperature gradient that reproduces the temperature state in the pulling furnace with the main purpose of reproducing the thermal history state in the pulling in the desired CZ method as the thermal history in the single crystal; By re-applying the thermal history by lowering the temperature to be equal to the state of moving the single crystal in the temperature gradient, the melt state and the subsequent pulling / cooling state are reproduced. The thermal history is reapplied so as to obtain a preferable crystal state. This makes it possible to determine the value of V / G purely considering only the Grown-in defect state regardless of the pulling speed when the single crystal is actually grown. Sometimes, the grown-in defect state only needs to be taken into account in the thermal history re-applying process, so that workability is improved and a single crystal having a desired grown-in defect state can be easily manufactured.
In the present invention, the first direction is not limited to the above-described vertical upward direction. For example, the first direction may be a radial direction or an oblique direction, and is not particularly limited.

According to the present invention, the temperature gradient and the temperature drop rate correspond to the pulling rate V and the crystal temperature gradient G in the pulling axis direction near the solid-liquid interface when pulling up the semiconductor single crystal using a single crystal pulling apparatus. The thermal history is reapplied so that the V / G value as a ratio thereof falls within a predetermined range. For example, in the thermal history reapplying step, the V / G value is changed to 0 so that the crystal is in a defect free state. 18 to 0.24 mm ² / (min ° C.). This makes it possible to realize a silicon single crystal that is in a defect-free internal state without worrying about condition control during pulling.

More specifically, the semiconductor manufacturing apparatus of the present invention includes a heat treatment furnace for controlling a crystal state contributing to a grown-in defect in the semiconductor single crystal, and the heating means for overheating the heat treatment furnace, Control means for controlling the temperature in the heat treatment furnace by the heating means, and controlling the temperature of the heat treatment furnace so that the single crystal is heated and maintained at a heat history reset temperature for resetting a heat history during crystal production. Heat treatment reset control, and after the heat history reset control, the heat treatment furnace is configured to re-apply a heat history that lowers the single crystal from the heat history reset temperature and sets the grown-in defect state to a desired state. Heat history re-applying control for controlling the temperature gradient in the first direction and the cooling rate can be performed.
At this time, in order to utilize various data collected during the pulling up so far, a reset heating means similar to a crucible for melting the semiconductor raw material and a hot zone for cooling the crystal during the pulling, and It is preferable to arrange a heating means for heat-treating the single crystal in a manner similar to the speed on the pulling side for controlling the crystal pulling speed and the rising speed of the crucible by arranging the gradient heating means of the heat history reapplying means. . That is, both the reset heating means that is cylindrical like a crucible, and the heat history re-applying means so as to form a temperature gradient that gradually decreases so as to cool continuously in the hot zone above this A heater having a function may be provided in a columnar shape (cylindrical shape) to serve as a heating unit, and a control unit may be provided that controls the reset heating control and heat history reapplying control. In this case, after the single crystal is heated for a predetermined time inside the heater as the reset heating means, the control means is used as the heat history reapplying means, for example, while maintaining the temperature gradient formed in the vertical direction. By lowering the temperature in the heater, the thermal history is reset and reapplied.
In addition, since formation of a temperature gradient is easier to form when the upper part is hot, the heating means can be controlled so that the upper side is higher and the lower side is lower than the actual lifting machine.
Furthermore, the temperature gradient of the heating means may be lowered in the direction of the temperature inside the pulling furnace, and the apparatus configuration itself does not stick to the cooling direction such as the vertical direction or the horizontal direction. is there.

In the present invention, the structure of the heating means is not limited as long as a temperature gradient can be formed and the temperature can be decreased at a predetermined temperature decrease rate. For example, heat treatment such as rapid cooling from the silicon melting point to 1300 ° C. is performed. In some cases, it is possible to use a coolable means, specifically a temperature exchanger or the like.
Furthermore, it is possible to provide not only a cylindrical (cylindrical) heater but also a radial heater positioned above and below the single crystal in the single crystal radial direction. Specifically, a heating means such as a halogen lamp used in a single-wafer type lamp heating furnace or the like can be used.

In the manufacturing method of the present invention, before the reset heating step, by having a slicing step of separating the single crystal in the axial direction into a single crystal ingot, a heat history reset heating step and a heat history re-applying step, In both the steps, reset heating and re-application of thermal history can be performed on a single crystal ingot in which the single crystal obtained by pulling or the like is separated in the axial direction to have a desired height. As a result, in order to reset the heat history in the reset heating process, the crystal is prevented from being deformed by its own weight when heated to the vicinity of the melting point, and can be heated for the time necessary for resetting the heat history. be able to.
Further, the heat treatment furnace includes a support portion that can support the single crystal ingot even when the single crystal ingot obtained by dividing the semiconductor single crystal in the axial direction is placed and heated to the thermal history reset temperature. Thus, the above manufacturing method can be performed. Specifically, it can be set as the structure which has a mounting tray etc. which mounts a single crystal ingot.

In the manufacturing method of the present invention, the reset heating step and the heat treatment re-applying step may be performed simultaneously on the plurality of single crystal ingots, thereby being divided with respect to the axial dimension of the single crystal at the time of pulling. A plurality of single crystal ingots can be processed simultaneously to improve workability.
Here, according to the present invention, the heat treatment furnace can support the plurality of single crystal ingots at the same time, whereby the manufacturing method described above is possible. Specifically, the support means provided in the heat treatment furnace has a structure having a plurality of support parts in the temperature gradient direction, a structure in which a plurality of single crystal ingots can be simultaneously placed on one support part, or a combination thereof. It is possible to adopt a configuration as follows.

  Further, when the silicon single crystal is pulled, the silicon single crystal is pulled without considering the control of the grown-in defects in the silicon single crystal, and after the pulling of the silicon single crystal is finished, the defect control in the silicon single crystal is controlled. By performing the thermal history reset and the re-applying heat treatment for performing the above, it is possible to facilitate the grown-in defect control, that is, the control of the V / G value, compared with the conventional pulling of the silicon single crystal.

  That is, when pulling up a silicon single crystal, the parameters to be considered for controlling the grown-in defect state in the silicon single crystal are reduced, the single crystal manufacturing efficiency is improved and a single crystal having a desired grown-in defect state can be easily obtained. Can be obtained. In addition, regarding the control of the diameter of the silicon single crystal, the heat from the silicon melt, the oxygen concentration, etc., which have been controlled at the time of the conventional pulling, the heat history reapplying such as the reset heating process and the heat history reapplying process described above There is almost no need to consider during heat treatment. Therefore, since the factor that inhibits the control of the V / G value is reduced, the control of the V / G value can be facilitated. Therefore, compared with the conventional technique, It is possible to reduce the influence of the time-dependent change of the apparatus and the change of conditions for each batch on the quality of the silicon single crystal, such as deterioration of the heat insulating material and change of the emissivity of the inner wall surface of the chamber. As a result, the yield can be greatly improved while maintaining the desired crystal quality.

  Further, the present inventor has found that the heat treatment after pulling the silicon single crystal may be performed as follows. Whether a void defect, an interstitial Si defect, or no defect occurs in a silicon single crystal is determined by the fact that the silicon single crystal is pulled up when the silicon single crystal is pulled up. It is determined by the balance of interstitial Si concentration that moves from bottom to top according to the pore concentration and diffusion. Therefore, the silicon single crystal after pulling is given a temperature history when a silicon single crystal having a desired defect region or a desired defect-free region is grown from a silicon melt, and the movement phenomenon of vacancies and interstitial Si is observed. By reproducing as a heat treatment relating to the thermal history, a silicon single crystal having a desired defect region or a desired defect-free region can be obtained.

At the time of pulling up the silicon single crystal, the temperature of the silicon single crystal solidified at the solid-liquid interface decreases as the crystal is pulled up. The behavior of vacancies and interstitial Si in the process of lowering the temperature of a silicon single crystal is understood as follows.
The vacancies and interstitial Si are taken in when pulling up the silicon single crystal. The vacancy concentration is higher in the vacancy concentration and interstitial Si concentration taken in at the solid-liquid interface when the upper portion of the silicon single crystal is pulled up. The high vacancy concentration part rises as the silicon single crystal is pulled up. On the other hand, as a diffusion phenomenon, between the vacancies and the interstitial Si, the interstitial Si diffusion rate exceeds that of the vacancies. Since interstitial Si moves from a high temperature to a low temperature due to diffusion, it rises from the bottom to the top of the crystal. In the silicon single crystal solidified at the solid-liquid interface, the pair annihilation reaction between the vacancies and interstitial Si occurs in the process of the temperature decreasing with the pulling. It is irrelevant to the difference in Si concentration.

  Furthermore, the present inventor has conducted extensive research and determines whether a void defect, an interstitial Si defect, or no defect occurs in a silicon single crystal. It was found to be determined by the difference in the Si concentration. That is, when the interstitial Si concentration is lower than the vacancy concentration at about 1250 ° C., void defects are generated, and when the interstitial Si concentration is higher than the vacancy concentration, interstitial Si defects are generated. When the hole concentration and the interstitial Si concentration are substantially equal, no defect is present.

  For this reason, the silicon single crystal manufacturing apparatus of the present invention is for performing heat treatment on the silicon single crystal pulled using a single crystal pulling apparatus that grows the silicon single crystal while pulling it from the silicon melt contained in the crucible. A heat treatment furnace, and a control means for controlling the temperature in the heat treatment furnace, the control means comprising a heating means in the heat treatment furnace so that the silicon single crystal has a defect reset temperature (thermal history reset temperature). A first control to be controlled (reset heating control), and a temperature history when a silicon single crystal having a desired defect region or a desired defect-free region is grown from the silicon melt after the first control. And performing a second control (thermal history reapplying control) for controlling the temperature gradient in the first direction in the heat treatment furnace with respect to the heat treatment time. It can be.

  The method for producing a silicon single crystal according to the present invention includes a single crystal growth step for growing a silicon single crystal from a silicon melt contained in a crucible while pulling the silicon single crystal grown in the single crystal growth step. A heat treatment step (heat history reset and reapplying step affecting Grown-in defects) that heat-treats in a heat treatment furnace, and the heat treatment step heats the silicon single crystal to a defect reset temperature ( Silicon having a desired defect region or a desired defect-free region in the silicon single crystal after the heating step by controlling a temperature gradient in a first direction in the heat treatment furnace with respect to a heat treatment time and a reset heating step) A temperature control step (thermal history re-applying step) that gives a temperature history when growing a single crystal from the silicon melt Characterized in that was.

  In the present invention, “defect reset temperature (thermal history reset temperature)” refers to oxygen precipitates, voids, etc. inherent in the silicon single crystal while maintaining the shape of the silicon single crystal grown in the single crystal growth step. This refers to the temperature at which secondary defects (Grown-in defects) are erased and the rebalance between the amount of vacancies and the amount of interstitial Si is possible, specifically 1320 ° C. to less than the melting temperature It means temperature, and more preferably 1350 ° C. to less than the melting temperature. Here, the reset heating time is determined in relation to the reset temperature. When the reset temperature is high, the reset heating time is short, and when the reset temperature is low, the reset heating time is long. . Specifically, the temperature is preferably 1400 ° C., 10 minutes or more, 1350 ° C., 30 minutes or more.

According to the present invention, a single crystal growth step for pulling up the silicon single crystal, and a heat treatment step (reset heating step and thermal history re-applying step) for performing heat treatment on the silicon single crystal grown in the single crystal growth step, Each can be performed within a control range of independent V / G values. Therefore, it is easy to control the V / G value, which is an index for determining the crystal defect state, when the conventional silicon single crystal is pulled up.
That is, in the single crystal growth process, as described above, it is not necessary to consider the defects in the silicon single crystal, so that the V / G value outside the range required for controlling the crystal defect state at the time of pulling is out. Can be done. Therefore, the silicon single crystal can be easily grown so that the diameter of the silicon single crystal is within a predetermined range. In the heat treatment process, as described above, parameter control such as the diameter of the silicon single crystal, heat from the silicon melt, contamination by impurities, oxygen concentration, etc. is excluded during the heat treatment and only the control of the grown-in defect is performed. Therefore, the heat treatment can be easily performed within a control range of an optimum V / G value that makes a silicon single crystal having a desired defect region or a desired defect-free region. Therefore, the manufacturing efficiency can be improved and the yield can be improved in a single crystal in a desired Grown-in defect state.

Further, in the single crystal growth step of the present invention, the control range of the V / G value can be expanded, and the silicon single crystal can be easily grown in the control range of the V / G value. When a silicon single crystal is grown at the maximum pulling speed with a diameter within a predetermined range, a silicon single crystal with a silicon single crystal with a diameter within a predetermined range is much faster than the conventional technology. Can be grown.
Further, in the heat treatment according to the present invention, it is not necessary to move the silicon single crystal, and the heat treatment can be performed with the silicon single crystal fixed. Therefore, the temperature gradient in the first direction in the heat treatment furnace with respect to the heat treatment time is controlled. Thus, the V / G value can be easily controlled. Therefore, the control can be easily performed as compared with the case where the pulling speed or the moving speed of the single crystal is controlled as a parameter.

Further, in the silicon single crystal manufacturing apparatus and manufacturing method of the present invention, the temperature history is measured in the pulling axis direction near the solid-liquid interface with the pulling speed V when the silicon single crystal is pulled using the single crystal pulling apparatus. The V / G value, which is the ratio with the crystal temperature gradient G, can be made the same as when it is in a predetermined range.
By using such a silicon single crystal manufacturing apparatus and manufacturing method, an apparatus capable of easily manufacturing a silicon single crystal having a defect region having a desired state or a desired defect-free region is obtained.

In the silicon single crystal manufacturing apparatus and method of the present invention, the heat treatment furnace has a support portion on which the silicon single crystal ingot obtained by slicing the silicon single crystal is placed, and is mounted on the support portion. The placed single crystal ingot can be heat treated.
By using such a silicon single crystal manufacturing apparatus and manufacturing method, a silicon single crystal ingot having a desired defect region or a desired defect-free region can be easily manufactured. Moreover, temperature control in the heat treatment process is further facilitated. Furthermore, since the heat treatment furnace does not have to have a large portion for controlling the magnetic field application device, furnace pressure, thermal radiation, etc. necessary for pulling up, the heat treatment furnace can be downsized compared to the pulling device. .

Further, in the method for producing a silicon single crystal according to the present invention, when the speed and temperature gradient for lowering the silicon single crystal are V, the pulling speed is V, and the temperature gradient near the solid-liquid interface is G, the V / G value. Can be set to 0.18 to 0.24 mm ² / (min ° C.).
By adopting such a silicon single crystal manufacturing method, the silicon single crystal can be brought into a state free from defects due to vacancies and defects due to interstitial silicon.

    According to the present invention, a semiconductor single crystal having a desired Grown-in defect state can be easily manufactured with a high yield.

Hereinafter, a semiconductor single crystal manufacturing apparatus and manufacturing method according to a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of a silicon single crystal pulling apparatus used in the present invention.
In FIG. 1, reference numeral 4 denotes a crucible. The crucible 4 includes a bottomed cylindrical quartz inner layer holding container 4a and a similarly bottomed cylindrical graphite outer layer holding container 4b fitted to the outside of the inner layer holding container 4a. The crucible 4 is supported by a support shaft 7 that rotates at a predetermined speed. A heater 6 is disposed concentrically outside the crucible 4. The crucible 4 is filled with a silicon melt 5 melted by a heater 6, and a pulling shaft 3 made of a pulling rod or a wire is disposed on the central axis of the crucible 4. On the upper side of the crucible 4, a gas flow rectifying cylinder 9 and the like are provided to form a hot zone. A seed chuck 2 and a seed crystal 1a are attached to the tip of the pulling shaft 3.

FIG. 2 is a schematic sectional view showing an example of a heat treatment furnace and control means constituting the present invention. In FIG. 2, reference numeral 10 denotes a heat treatment furnace for performing heat treatment on the silicon single crystal ingot 17, and reference numeral 11 denotes control means for controlling the temperature in the heat treatment furnace 10.
In the heat treatment furnace 10, a cylindrical heater (heating means) 14 connected to the control means 11 via the wiring 15 is disposed, and a silicon single crystal ingot 17 can be disposed in the center of the cylindrical heater 14. It is said that. The inside of the heat treatment furnace 10 is controlled by the control means 11 so that the temperature of the silicon single crystal ingot 17 is uniformly maintained at a defect reset temperature (heat history reset temperature) of 1320 ° C. to less than the melting temperature in the heating process described later. It is possible. Further, in the heat treatment furnace 10, a temperature history equal to that at the time of pulling up a silicon single crystal having a desired grown-in defect region or a desired defect-free region from a silicon melt is obtained in a temperature control step described later. As given to the ingot 17, it is possible to control so as to form a temperature gradient in the vertical direction that is high and low in the heat treatment time.

The control means 11 includes a first control (thermal history reset control) that controls the heat treatment furnace 10 so that the silicon single crystal ingot 17 has a defect reset temperature of 1320 ° C. to less than the silicon melting point temperature, and a desired control after the first control. The temperature gradient in the vertical direction and the temperature drop in the heat treatment furnace 10 with respect to the heat treatment time so as to give the silicon single crystal ingot 17 a temperature history when a silicon single crystal having a defect region or a desired defect-free region is grown from the silicon melt. The second control (heat history reapplying control) for controlling the speed is performed.
As a function of the control means 11, a program for realizing the first control and the second control is loaded from a storage device (memory) provided in the control means and executed by a CPU (central processing unit). It is assumed that this function is realized. Specifically, for example, the temperature of the silicon melt 5 in the crucible 4 or the like is controlled by a conventional control device used for controlling the V / G value when the silicon single crystal is pulled using a single crystal pulling device, and In a state corresponding to the control of the pulling speed and the temperature state of the hot zone, it can be used as a control means for performing the first control and the second control.

Next, a method for manufacturing a silicon single crystal according to the first embodiment of the present invention will be described.
(Single crystal growth process)
First, the seed crystal 1a is brought into contact with the surface of the silicon melt 5 accommodated in the crucible 4 using the single crystal pulling apparatus shown in FIG. The silicon single crystal 1 formed by solidifying the silicon melt is grown by pulling up the pulling shaft 3 while rotating at a speed.
When the silicon single crystal 1 is grown, first, seeding is performed to make the silicon single crystal 1 dislocation-free to form the neck portion 1b, and then a shoulder is used to obtain a necessary diameter as a body. Grow 1c. When the silicon single crystal 1 reaches the required diameter, the shoulder is changed to grow the straight body 1d having a constant diameter. After growing up to the required length of the straight body portion 1d, tail squeezing is performed to separate the inside of the straight body portion 1d from the melt in a dislocation-free state. When the silicon single crystal 1 is separated from the melt, the silicon single crystal 1 is taken out of the furnace under a predetermined condition and cooled. After cooling, the silicon single crystal 1 is sliced into a silicon single crystal ingot 17.
At this time, the pulling speed of the silicon single crystal 1 can be the fastest pulling speed at which the single crystal state can be maintained and the desired diameter can be maintained, and is limited by the pulling speed in consideration of Grown-in defects. There is nothing to do.

The size of the silicon single crystal ingot 17 here is about 110 to 460 mm in diameter and 500 mm or less in thickness (height). If this upper limit is exceeded, the heat treatment furnace becomes large, which is not preferable.
In the case of the ingot 17 having a large diameter, a temperature distribution is easily formed in the radial direction of the ingot 17 in a heat treatment process described later, and when the target temperature drop rate is fast, it is difficult to make the temperature distribution uniform, which is not preferable. More specifically, when the diameter is large and the temperature decreasing rate is high, the inside of the crystal is easily left at a high temperature, and the temperature distribution is likely to be generated in the radial direction. In order to achieve a uniform temperature distribution, it is necessary to cool the ingot slowly, and the temperature drop rate of the ingot must be reduced, resulting in lower productivity. Therefore, it is more preferable that the diameter is 300 mm or less for a Φ300 mm crystal ingot and 400 mm or less for a Φ200 crystal ingot.

(Heat treatment process)
Next, using the heat treatment furnace and the control means shown in FIG. 2, the thermal history for controlling the grown-in defect distribution state in the silicon single crystal ingot 17 formed in the single crystal growth step is reset and regenerated. A heat treatment step for performing control for imparting is performed.
First, as shown in FIG. 2, the silicon single crystal ingot 17 is placed at the center position of the heater 14 so that the crystal growth axis is in the center axis direction (vertical direction) of the heat treatment furnace 10 and at the same position as the center axis of the heater 14. And the control means 11 controls the heater 14 (first control) so that the inside of the heat treatment furnace 10 becomes about the silicon melting point temperature, and the temperature of the silicon single crystal ingot 17 is 1320 ° C. Heating is performed so that the defect reset temperature is lower than the melting temperature (reset heating step). By this reset heating process, the thermal history applied to the ingot 17 in the pulling process is reset, whereby secondary defects (Grown-in such as oxygen precipitates and voids existing in the silicon single crystal ingot 17 are reset. Defect) is erased. Subsequently, the control means 11 controls the heater 14 to control the temperature gradient and the temperature drop rate in the vertical direction in the heat treatment furnace 10 with respect to the heat treatment time (second control), and in the heater (heat treatment reapplying means) 14. A predetermined temperature gradient is formed so that the upper side in the vertical direction becomes lower, and the ingot 17 is cooled in a state in which the formed temperature gradient is maintained, whereby a desired defect region is formed in the silicon single crystal ingot 17 after the heating process. Alternatively, a thermal history in a state equal to the thermal history when a silicon single crystal having a desired defect-free region is grown from the silicon melt is reapplied (thermal history reapplying step).

Here, for example, when the silicon single crystal ingot 17 is made defect-free, the temperature history in the temperature control step is the pulling speed V when pulling up the silicon single crystal using the single crystal pulling device and pulling up near the solid-liquid interface. The second control is performed by the control means 11 so that the V / G value, which is the ratio with the crystal temperature gradient G in the axial direction, is the same as when the value is 0.18 to 0.24 mm ² / (min ° C.). As a result, the silicon single crystal ingot 17 is adjusted so that the interstitial Si concentration and the vacancy concentration are substantially equal in the temperature control step in the heat treatment furnace 10, thereby eliminating defects.

Further, for example, in the case of the silicon single crystal ingot 17 having void defects, the temperature history in the temperature control step is the pulling speed V when the silicon single crystal is pulled using a single crystal pulling device and the pulling axis near the solid-liquid interface. The second control is performed by the control means 11 so that the V / G value, which is the ratio with the crystal temperature gradient G in the direction, exceeds 0.24 mm ² / (min ° C.). Thus, the silicon single crystal ingot 17 is adjusted so that the interstitial Si concentration is lower than the vacancy concentration in the temperature control step in the heat treatment furnace 10 and has void defects.

Further, for example, in the case of the silicon single crystal ingot 17 having interstitial Si defects, the temperature history in the temperature control step is the pulling speed V when the silicon single crystal is pulled using a single crystal pulling device and the vicinity of the solid-liquid interface. The second control is performed by the control means 11 so that the V / G value, which is the ratio to the crystal temperature gradient G in the pulling axis direction, is the same as when V / G is less than 0.18 mm ² / (min ° C.). Thus, the silicon single crystal ingot 17 is adjusted so that the interstitial Si concentration is higher than the vacancy concentration in the temperature control step in the heat treatment furnace 10, and has an interstitial Si defect.

The silicon single crystal ingot 17 obtained in this way has a desired defect region or a desired defect-free region. By processing this, a woofer used as a substrate material for various devices can be obtained. Can do.
As described above, in the pulling process as the pre-heat treatment stage of the present invention, the pulling speed of the silicon single crystal 1 is the fastest pulling speed at which the single crystal state can be maintained and the desired diameter can be maintained. In the thermal history reset and thermal history re-applying process, the single crystal diameter or the temperature gradient formed in the pulling furnace is not limited. Therefore, it is possible to control the single crystal outer shape formation and the grown-in defect distribution in separate processes, respectively, so that compared with the conventional manufacturing method in which these two factors are simultaneously controlled at the time of pulling up. The crystal defect state and the outer shape can be easily controlled. Furthermore, since it is only necessary to control the output of the heater 14 by the control means 11 and it is not necessary to control parameters such as the moving speed of the ingot 17, the desired temperature state (thermal history reset temperature, temperature gradient, temperature drop rate) can be easily obtained. ) Can be realized. Therefore, it is possible to easily produce a grown-in defect-free single crystal that has been difficult to control until now, and to produce a desired single crystal with a high yield.
In this embodiment, the heater 14 has a cylindrical shape having an axis in the vertical direction, and thus a temperature gradient is formed in the vertical direction. However, the present invention is not limited to this, and a temperature gradient that drops in any direction is formed. It is also possible to reset and re-apply the thermal history.

Next, a single crystal single crystal manufacturing apparatus and manufacturing method according to a second embodiment of the present invention will be described. In the second embodiment, the single crystal pulling apparatus shown in FIG. 1 can be used as in the first embodiment. FIG. 3 is a schematic sectional view showing another example of a heat treatment furnace constituting the present invention. In the second embodiment, description of the same parts as those in the first embodiment will be omitted, and only different parts will be described.
The heat treatment furnace and the control means shown in FIG. 3 are different from those in FIG. 2 in that the heater 18 is connected to the control means 11 via the wiring 13 in the heat treatment furnace 10 and heats the silicon single crystal ingot 17 from above. A heater 19 connected to the control means 11 via the wiring 13 and for heating the silicon single crystal ingot 17 from below is disposed.

Next, a method for manufacturing a silicon single crystal according to the second embodiment of the present invention will be described.
In the second embodiment of the present invention, in the heating step, as shown in FIG. 3, the silicon single crystal ingot 17 is placed at the center of the heater 14, and the heaters 14, 18, 19 are controlled by the control means 11. By doing (first control), the silicon single crystal ingot 17 is heated from the side surface, the upper surface, and the lower surface so that the temperature of the silicon single crystal ingot 17 becomes a defect reset temperature of 1350 ° C. to less than the melting temperature. Subsequently, the control means 11 controls the heaters 14, 18, 19 to control the temperature gradient in the vertical direction in the heat treatment furnace 10 with respect to the heat treatment temperature and the temperature drop rate more precisely (second control), thereby resetting. A thermal history equal to a thermal history for growing a silicon single crystal having a desired defect region or a desired defect-free region from the silicon melt is given to the silicon single crystal ingot 17 after the heating step (thermal history reapplying step), A silicon single crystal ingot 17 having a desired defect region or a desired defect-free region is manufactured.

In the embodiment described above, the inside of the heat treatment furnace 10 can be controlled so as to form a temperature gradient in the vertical direction where the bottom is high and the top is low, but the vertical direction where the top is high and the bottom is low. The temperature gradient may be controlled so as to form the following temperature gradient. In this case, temperature control becomes easy. Further, the inside of the heat treatment furnace 10 may be controlled so as to form a temperature gradient in the left-right direction, and the direction of the temperature gradient in the heat treatment furnace 10 is not particularly limited.
Further, the heaters 12, 18, and 19 are illustrated as being integral with each other, but these are divided into a plurality of parts so that more precise temperature state control can be realized, and each can be output-controlled by the control means 11. It is also possible to make it.

Further, as in the present embodiment, heaters (heating means) 14, 18, and 19 are provided so as to wrap the ingot 17 from the entire top, bottom, left and right, and these are controlled to form a temperature gradient in the radial direction of the ingot 17. Thus, it is possible to re-apply the thermal history as a heat treatment different from the temperature gradient at the time of pulling up, the temperature lowering rate, and the like. Alternatively, the diameter dimension and the axial dimension are set so as to be as close to a sphere as possible, like a single crystal in which the straight body part 1c of the same size as the diameter dimension is formed without cutting the neck part 1b and the bottom, that is, A shape having a small specific surface area and a shape close to the same shape of heat radiation on the entire surface is located inside the heat treatment furnace 10 and the single crystal close to the spherical shape is cooled in a substantially uniform temperature state in the furnace. Thus, it is possible to form a radial temperature gradient from the center of the single crystal to the surface and reapply the thermal history.
Further, as shown in the above-described embodiment, the heat treatment furnace and the control means can be separated, but the heat treatment furnace and the control means may be integrated.

Next, a semiconductor single crystal manufacturing apparatus and manufacturing method according to a third embodiment of the present invention will be described. 5 and 6 are schematic sectional views showing other examples of the heat treatment furnace constituting the present invention. In addition, in this embodiment, description is abbreviate | omitted about the part same as 1st, 2nd embodiment, and only a different part is demonstrated.
The heat treatment furnace shown in FIG. 5 is different from the heat treatment furnace shown in FIG. 2 in that a support means 16 is provided in the heat treatment furnace 10 and a plurality of mounting plates 16a and 16c supported by a support shaft. The crystal ingot 17 is supported at the same time. The mounting tray 16c is fixed to the mounting tray 16a by a support 16d. The mounting tray 16a and the mounting tray 16c are positioned at different positions in the vertical direction, and the silicon single crystal ingots 17 and 17 mounted on the mounting trays 16a and 16c are the diameters of the silicon single crystal ingot 17, respectively. It is provided so that it may become the same position with respect to a direction.

In the heat treatment furnace 10 shown in FIG. 5, the silicon single crystal ingots 17 and 17 are supported by the supporting means 16 so that the center of the plurality of silicon single crystal ingots 17 and 17 and the center of the heater 14 are centered within the heating means 12. 17 is supported in the same position with respect to the radial direction of 17 and can be moved up and down in the heat treatment furnace 10 with the center of the silicon single crystal ingots 17 and 17 and the center of the heater 14 being the same. It is said that.
As a result, a plurality of ingots 17 can be processed simultaneously, and the ingot 17 can be moved in the heat treatment furnace 10 in the vertical direction, that is, in the direction of the temperature gradient. In addition to the above control, the temperature state of the ingot 17 can be more precisely controlled by the vertical movement of the support means 16.
Further, the heat treatment while rotating the ingot 17 is preferable because the temperature distribution is made uniform in the circumferential direction.

Further, the heat treatment furnace shown in FIG. 6 is different from the heat treatment furnace shown in FIG. 2 in that the heat treatment furnace 10 is provided with support means 16 and includes a plurality of mounting dishes 16a supported by a support shaft, and a plurality of silicon single pieces. The crystal ingot 17 is supported at the same time. On the mounting tray 16 a, the silicon single crystal ingots 17 and 17 are placed at different positions in the left-right direction so as to be a target position with respect to the central axis of the heater 14.
In the heat treatment furnace 10 shown in FIG. 6, the silicon single crystal ingots 17 and 17 are supported by the support means 16 at positions symmetrical to the central axis of the heating means 12 and mounted. The dish 16a can be moved up and down in the heat treatment furnace 10 in the vertical direction.
As a result, a plurality of ingots 17 can be processed simultaneously, and the ingot 17 can be moved in the heat treatment furnace 10 in the vertical direction, that is, in the direction of the temperature gradient. In addition to the above control, the temperature state of the ingot 17 can be more precisely controlled by the vertical movement of the support means 16.

(Experimental example 1)
(Single crystal growth process)
First, using the single crystal pulling apparatus shown in FIG. 1, the seed crystal 1a is brought into contact with the surface of the silicon melt 5 accommodated in the crucible 4 and rotated at a predetermined speed on the same axis as the support shaft 7, A silicon single crystal was grown by pulling up the pulling shaft 3.
The pulling conditions at this time are a pulling speed of 1.0 mm / min, a pulling diameter of 213 mm, a straight body length of 1000 mm, and a V / G value of 0.33 mm ² / ° C. min.
Thereafter, the obtained silicon single crystal was sliced to obtain a silicon single crystal ingot of Φ210 mm × 100 mm. The FDP of a sample obtained by slicing the same silicon single crystal as the silicon single crystal ingot was examined by the following method. That is, the surface of the sample was eroded with a fluorinated nitric acid solution to form a mirror, and then immersed in a Secco etching solution (pure water + hydrofluoric acid + potassium dichromate solution) vertically without stirring and observed with an optical microscope. Detected by the method. As a result, FDP was detected.

(Heat treatment process)
Next, a heat treatment step for controlling defects in the silicon single crystal ingot was performed using the heat treatment furnace and the control means shown in FIG. First, a silicon single crystal ingot is placed at the center of the heater 14 in the heat treatment furnace 10, and the heater 14 is controlled by the control means 11 (first control), so that the defect reset temperature is 1,400 ° C. for 5 hours. Heated (heating step). Thereafter, the heater 14 is controlled by the control means 11 (second control), and the temperature gradient of 2 ° C./mm in the vertical direction inside the silicon single crystal ingot is caused by the temperature gradient in the vertical direction in the heat treatment furnace 10 with respect to the heat treatment time. The temperature history of the formed silicon single crystal ingot after the heating step was given to the silicon single crystal ingot after the heating step (temperature control step) at a rising speed (mm / min) shown in Table 1 until it reached 500 ° C. or lower. Thereafter, the silicon single crystal ingot 17 was taken out of the heat treatment furnace 10 and evaluated. The results are shown in Table 1.

(Experimental example 2)
(Single crystal growth process)
First, using the single crystal pulling apparatus shown in FIG. 1, the seed crystal 1a is brought into contact with the surface of the silicon melt 5 accommodated in the crucible 4 and rotated at a predetermined speed on the same axis as the support shaft 7, A silicon single crystal was grown by pulling up the pulling shaft 3.
The pulling conditions at this time are a pulling speed of 0.3 mm / min, a pulling diameter of 213 mm, a straight body length of 1000 mm, and a V / G value of 0.10 mm ² / ° C. min.
Thereafter, the obtained silicon single crystal was sliced to obtain a silicon single crystal ingot of Φ210 mm × 100 mm. The interstitial Si defects of the sample obtained by slicing the same silicon single crystal as the silicon single crystal ingot were examined by the same method as the FDP detection method in Experimental Example 1. As a result, interstitial Si defects were detected.
(Heat treatment process)
Next, a heat treatment step was performed in the same manner as in Experimental Example 1. The result was the same as Experimental Example 1 shown in Table 1.

  As shown in Table 1, when the ascent rate is 0.3 (mm / min) or less, there are interstitial Si defects, and when the ascent rate is 0.4 (mm / min), there are no defects and the ascent rate is 0. In the case of .5 (mm / min) or more, one having a void defect was obtained. Accordingly, even a silicon single crystal ingot obtained from a silicon single crystal in which FDP is detected or a silicon single crystal ingot obtained from a silicon single crystal in which interstitial Si defects are detected is similarly applied. It was confirmed that a silicon single crystal ingot having a desired defect region or a desired defect-free region can be produced by performing the heat treatment step of the present invention.

It is the schematic sectional drawing which showed an example of the single crystal pulling apparatus used in this invention. It is the schematic sectional drawing which showed an example of the heat processing furnace which comprises this invention. It is the schematic sectional drawing which showed the other example of the heat processing furnace which comprises this invention. It is a defect distribution map in the longitudinal section of a single crystal grown while gradually reducing the pulling rate. It is the schematic sectional drawing which showed another example of the heat processing furnace which comprises this invention. It is the schematic sectional drawing which showed another example of the heat processing furnace which comprises this invention.

Explanation of symbols

1a: seed crystal, 2: seed chuck, 3: lifting shaft, 4: crucible, 4a: inner layer holding container, 4b: outer layer holding container, 5: silicon melt, 6: heater, 7: support shaft, 9: gas Flow rectifier, 10: heat treatment furnace, 11: control means, 13: wiring, 14: heater, 15: wiring, 17: silicon single crystal ingot, 18: heater, 19: heater.

Claims (14)

An apparatus for manufacturing a semiconductor single crystal for controlling a Grown-in defect inside a semiconductor single crystal,
Reset heating means for heating and maintaining the single crystal at a thermal history reset temperature for resetting a thermal history at the time of crystal production that affects a Grown-in defect state inside the single crystal;
A thermal history reapplying means for lowering the single crystal from the thermal history reset temperature and reapplying a thermal history that makes the grown-in defect state a desired state;
An apparatus for producing a semiconductor single crystal, comprising: The reset heating means and the heat history re-applying means are the same heating means,
When the semiconductor single crystal is continuously cooled from the thermal history reset temperature by controlling this heating means, a desired thermal history that affects the grown-in defect state inside the single crystal is reapplied. 2. The apparatus for producing a semiconductor single crystal according to claim 1, further comprising control means for controlling a heat treatment temperature and a temperature lowering rate. A heat treatment furnace for controlling Grown-in defects in the semiconductor single crystal;
The heating means for overheating the heat treatment furnace;
Control means for controlling the temperature in the heat treatment furnace by the heating means,
The control means controls the temperature in the heat treatment furnace so that the single crystal is heated and maintained at a thermal history reset temperature for resetting a thermal history at the time of crystal production that affects a grown-in defect state inside the single crystal. Heat history reset control,
After the thermal history reset control, the temperature gradient and rate of temperature decrease of the single crystal so that the single crystal is lowered from the thermal history reset temperature to re-apply the thermal history that makes the grown-in defect state a desired state. The apparatus for producing a semiconductor single crystal according to claim 2, wherein thermal history reapplying control is performed to control A heat treatment furnace for controlling crystal state contributing to Grown-in defects in the semiconductor single crystal;
The heating means for overheating the heat treatment furnace;
Control means for controlling the temperature in the heat treatment furnace by the heating means,
The control means controls the temperature of the heat treatment furnace so that the single crystal is heated and maintained at a thermal history reset temperature for resetting a thermal history at the time of crystal production that affects a grown-in defect state inside the single crystal. Thermal history reset control,
After the thermal history reset control, the single crystal is lowered from the thermal history reset temperature to reapply a thermal history that makes the grown-in defect state a desired state. The apparatus for producing a semiconductor single crystal according to claim 2, wherein thermal history reapplying control for controlling a temperature gradient and a temperature drop rate is performed.   The temperature gradient and the temperature drop rate in the heat treatment furnace correspond to the crystal temperature gradient G and the pulling rate V in the pulling axis direction near the solid-liquid interface when pulling up the semiconductor single crystal using a single crystal pulling apparatus. The apparatus for producing a semiconductor single crystal according to claim 3 or 4, wherein a thermal history is reapplied so that a V / G value as a ratio thereof falls within a predetermined range.   6. The heat treatment furnace according to claim 3, wherein the heat treatment furnace performs heat history resetting and re-applying heat treatment on a semiconductor single crystal ingot obtained by dividing the semiconductor single crystal in an axial direction. An apparatus for producing a semiconductor single crystal according to 1.   The apparatus for manufacturing a semiconductor single crystal according to claim 6, wherein the heat treatment furnace is configured to simultaneously support a plurality of the semiconductor single crystal ingots so that a thermal history can be reset and reapplied. A method for producing a semiconductor single crystal for controlling a Grown-in defect inside the semiconductor single crystal,
A reset heating step of heating and maintaining the single crystal at a thermal history reset temperature for resetting a thermal history at the time of crystal production that affects a grown-in defect state inside the single crystal;
A thermal history reapplying step of lowering the single crystal from the thermal history reset temperature to reapply a thermal history that makes the Grown-in defect state a desired state;
A method for producing a semiconductor single crystal, comprising:   The method for producing a semiconductor single crystal according to claim 8, wherein the reset heating step and the thermal history reapplying step are continuously performed.   In the thermal history reapplying step, a temperature gradient and a temperature lowering rate of the single crystal are reapplied so as to reapply a thermal history that lowers the single crystal from the heat history reset temperature and makes the crystal state a desired state. The method for producing a semiconductor single crystal according to claim 9, wherein the method is controlled.   In the heat history reapplying step, the single crystal is lowered from the heat history reset temperature to reapply a heat history that makes the grown-in defect state a desired state. The method for producing a semiconductor single crystal according to claim 9, wherein the temperature gradient and the temperature lowering rate are controlled.   The temperature gradient and the temperature lowering rate correspond to the pulling rate V and the crystal temperature gradient G in the pulling axis direction in the vicinity of the solid-liquid interface when pulling up the semiconductor single crystal using the single crystal pulling apparatus. The method for producing a semiconductor single crystal according to claim 10 or 11, wherein the thermal history is reapplied so that the V / G value is within a predetermined range.   The semiconductor single crystal according to any one of claims 8 to 12, further comprising a slicing step of separating the semiconductor single crystal in an axial direction to form a semiconductor single crystal ingot before the reset heating step. Manufacturing method. The method for producing a semiconductor single crystal according to claim 8, wherein the reset heating step and the heat treatment re-applying step are simultaneously performed on the plurality of single crystal ingots.

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