JP2002145696A - Manufacturing method of silicon single crystal, silicon single crystal wafer and method of designing silicon single crystal manufacturing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of silicon single crystal, in which the optimum manufacturing condition to control the size and the density of grow-in defect caused by void to be a desired value is precisely obtained at the time of growing silicon single crystal using the CZ method. SOLUTION: The operation condition for growing silicon single crystal and the temperature condition inside the growing furnace are inputted in a computer as data. Next, the relation (fig. 2) between the size and the density of the grow-in defect caused by the void and the growing rate of the silicon single crystal is obtained by the simulation using the computer. The silicon single crystal is grown by selecting the growing rate to control the size and density of the grow-in defect caused by the void introduced into the inside of the crystal to be a desired value based on the simulation result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Czochralski method (hereinafter referred to as CZ method).
TECHNICAL FIELD The present invention relates to a method for manufacturing a silicon single crystal, a method for designing a silicon single crystal wafer, and a method for manufacturing a silicon single crystal manufacturing apparatus.

[0002]

2. Description of the Related Art With the recent increase in the degree of integration and size of semiconductor elements, electronic circuits constituting the semiconductor elements have been steadily miniaturized. As a result, the quality requirements of semiconductor wafers used as substrates for forming semiconductor elements are becoming stricter, and various measures have been taken to satisfy these requirements.

Here, a silicon single crystal pulled by the CZ method is most often used as a material for a semiconductor wafer. Since the crystal defects formed inside the crystal when growing the silicon single crystal greatly affect the device characteristics when the semiconductor device is formed on the surface layer of the silicon single crystal wafer, the silicon single crystal is grown by the CZ method. When growing a crystal, it is necessary to prepare operating conditions and a thermal environment so that a silicon single crystal having desired quality characteristics can be obtained.

[0004] In growing a silicon single crystal, a defect caused by crystal growth incorporated therein during the crystal growth, that is, a grown-in defect.
Is formed, and the state of formation of the grown-in defect differs depending on the growth rate of the single crystal and the cooling condition of the single crystal pulled from the silicon melt. For example, when a single crystal is grown with a relatively high pulling speed, silicon atoms in the single crystal tend to be insufficient. When the insufficient portion is aggregated, when the silicon single crystal is processed into a wafer, it appears on the surface in a shape of a concave portion or a hole. As described above, in this silicon single crystal, shortage of silicon atoms occurs, and point defects existing as vacancies between atoms are removed by vacancy (Vacanc).
y, hereinafter, may be abbreviated as V. ). Also,
In the silicon single crystal, a region in which a vacancy-induced glow-in defect is predominant, which is caused by vacancy aggregation, is referred to as a V region. Examples of such void-induced grown-in defects include FPD (Flow Pattern Defects), COP
(Crystal Originated Particle) or LSTD
(Laser Scattering Tomography Defects), etc., which are observed as octahedral void defects on the wafer surface when a silicon single crystal is processed into a wafer.

On the other hand, the pulling speed of the silicon single crystal is suppressed as much as possible, and for example, the crystal growth speed is set to 0.4 mm / min.
When the single crystal growth is performed to a degree of less than or equal to, the interstitial-Si (interstitial-Si: interstitial silicon atom (hereinafter abbreviated as I) in which extra silicon atoms exist between the lattices of the silicon single crystal. Point defects referred to as ")) are likely to occur. In the region inside the silicon single crystal where the interstitial-silicon is dominant, L / D (Large Dislodge), which is considered to be caused by dislocation loops,
cation: Abbreviation for interstitial dislocation loop, LSPD or L
Interstitial silicon defects, which are generally referred to as crystal defects such as FPD, are present at a low density. When a silicon single crystal is processed into a wafer to form a semiconductor element on a surface layer, current leakage or the like occurs. It can also cause serious failures.
The region inside the silicon single crystal where the interstitial-silicon becomes dominant is called an I region.

Therefore, if the silicon single crystal is pulled up using a single crystal growth condition intermediate between the condition in which the V region is dominant and the condition in which the I region is dominant, a shortage of atoms or an extra atom between silicon atoms is obtained. It is possible to grow a silicon single crystal in a state of neutral (hereinafter sometimes abbreviated as N), which does not exist or is slightly present. As described above, a region inside a silicon single crystal in a neutral state where there is no shortage of atoms or no surplus atoms between silicon atoms, or even if there are few atoms, is called an N region.

Note that N formed inside the silicon single crystal
An OSF (Oxidation I) is located between the region and the above-described V region.
There is a region called oxygen-induced defects or nuclei at high density called nduced stacking faults. When a silicon single crystal is processed into a wafer, the region is observed as a ring shape. Therefore, a region in which the OSF of the silicon single crystal or its nucleus exists at a high density is called an OFS ring or an OSF ring region.

Here, Japanese Patent Application Laid-Open No. H11-79889 discloses a technique for growing a silicon single crystal with no defects or suppressed as much as possible. Specifically, by adjusting the pulling speed and the temperature atmosphere in the vicinity of the crystal, a condition is selected such that the OSF ring closes at the crystal center and the entire surface becomes an N region, and a silicon single crystal is grown. It is claimed that a high-quality silicon single crystal having a low crystal defect density can be obtained while keeping the growth-in defect at an extremely low density. However, in this method, it is necessary to continue the growth while maintaining the pulling speed at a low speed accurately and substantially constant. Therefore, although there is an advantage that a high quality crystal with few crystal defects can be obtained, a silicon single crystal is obtained. There are many problems to be solved from the viewpoint of efficient mass production of.

On the other hand, Japanese Patent Application Laid-Open No. 11-186277 discloses that a silicon single crystal is positively pulled up at a high speed to grow it so that the V region becomes dominant. A method for eliminating a grown-in defect introduced during crystal growth is disclosed. The publication states that it is possible to produce single crystals without lowering the pulling speed during the growth of silicon single crystals, and it is possible to effectively suppress the occurrence of vacancy-induced grown-in defects while maintaining high productivity. Have been done.

[0010]

However, in order to achieve the above-mentioned effects in the method disclosed in JP-A-11-186277, the size (density) and density of the grown-in defect are appropriately controlled to desired values. There is a need to. For example, the size and density of a grown-in defect caused by vacancies such as FPD and COP are determined by a cooling rate when a silicon single crystal is grown. Therefore, it is conceivable that the size and density distribution of defects are likely to change greatly or vary depending on the cooling rate of the grown single crystal, and the defects cannot be eliminated even by heat treatment after wafer processing.

In order to prevent such a problem from occurring, before pulling a single crystal having a desired quality, the defect distribution and the like at the time of growing the single crystal are experimentally predicted and examined, and then a desired defect is obtained. It is effective to grow a silicon single crystal by selecting an operating condition such as a cooling heat history or a pulling speed that gives a distribution. However, in this method, while variously changing the pulling speed of the single crystal and the heat insulating effect of the in-furnace structure disposed inside the growth furnace, the manufacturing conditions that are considered to be optimal are found only experimentally, and the single crystal is manufactured. It is not guaranteed that the optimum conditions for obtaining the desired crystal quality can always be obtained. In addition, although it is a test production for determining operating conditions, the time and cost required to grow a silicon single crystal are considerable. As a result, it is not possible to carry out many tests unnecessarily, and it is necessary to select appropriate manufacturing conditions based on a small amount of data. It is doubtful that he was. In some cases,
It is not possible to find the optimum manufacturing conditions for obtaining the desired crystal quality, and it is quite possible that the operation may be performed at the expense of productivity and crystal quality.

Further, in consideration of productivity, in order to find operating conditions and an optimum atmospheric temperature in the growth furnace in which the density of the grown-in defects can be kept as low as possible, a method that relies on repetition of experiments is required. There is a limit. Finding the conditions that minimize the defect density or the operating conditions that maximize the defect size in response to the complex silicon semiconductor manufacturing conditions entails a great burden both technically and economically. Met.

An object of the present invention is to provide a silicon single crystal grown by using the CZ method so that the desired quality of the silicon single crystal, particularly the crystal characteristics, is superior to the V region. In the above, it is possible to accurately determine the optimum manufacturing conditions for setting the size and density of the vacancy-induced grown-in defects to desired values, and thus to efficiently produce a silicon single crystal having stable crystal quality, A method for manufacturing a silicon single crystal capable of widely controlling a grown-in defect introduced into a single crystal and meeting the quality requirements of a silicon single crystal in various senses, and a silicon single crystal wafer manufactured thereby,
And a method for designing a silicon single crystal manufacturing apparatus.

[0014]

Means for Solving the Problems and Actions / Effects In order to solve the above problems, the first of the methods for manufacturing a silicon single crystal according to the present invention is to manufacture a silicon single crystal using the Czochralski method. In the method, the operating conditions for growing the silicon single crystal and the temperature conditions inside the growth furnace are input as data to an electronic computer, and the size and density of the grown-in defect caused by vacancies introduced into the crystal and the silicon single crystal The relationship between the growth rate and the growth rate is determined by a simulation using an electronic computer, and the size and density of the grown-in defect caused by vacancies introduced into the crystal are set to desired values based on the simulation result. It is characterized by selecting a speed and growing a silicon single crystal.

The pulling speed of the silicon single crystal is increased so that the characteristics inside the single crystal are in the V region.
In order to find operating conditions such as an appropriate pulling speed for obtaining a desired value of the groin-in defect caused by vacancies such as P, various conditions for forming a temperature distribution of a growth furnace at the time of crystal growth in an electronic computer, In addition, it is effective to input operating conditions relating to pulling of a desired silicon single crystal or the like, and to obtain the size and density of the grown-in defect introduced into the single crystal by simulation. Then, if a silicon single crystal is grown thereafter, it is possible to grow a silicon single crystal having a defect distribution with a desired value without performing unnecessary single crystal pulling-up experiments and the like. .

In particular, operating conditions at which the size and density of the vacancy-induced grown-in defects introduced during the growth of a silicon single crystal become maximum or minimum, and temperature conditions inside the growth furnace, specifically, in the growth furnace With regard to the arrangement and structure of furnace internal structures such as rectifying cylinders and heat insulating materials to be arranged, the present invention seeks the optimum conditions, which is much more efficient and more efficient than conventional experimental methods alone. Be accurate. Further, the size and density of the grown-in defect can be selected from a wide range, and it becomes possible to provide a silicon single crystal having a variety of qualities.

In this case, before starting the growth of the silicon single crystal, the operating conditions for obtaining the desired crystal quality used in the simulation are adopted, the single crystal is actually grown, and a crystal substantially equivalent to the simulation is obtained. It is desirable to confirm whether or not it is possible to obtain a silicon single crystal having a defect, for example, to compare the relationship between the actually obtained value and the size and density of the defect obtained by simulation. By comparing the results obtained by the simulation with the actual operation, it is possible to correct errors in the calculation results by the simulation, and the operating conditions are further optimized, so that silicon units having characteristics closer to the required crystal quality are obtained. Crystal growth becomes possible.

Next, a second method of manufacturing a silicon single crystal according to the present invention is a method of manufacturing a silicon single crystal by using the Czochralski method, in which a grown-in defect caused by vacancies introduced into the crystal is eliminated. In order to minimize the density, the growth rate of the silicon single crystal is set to F (mm / min),
Given that the temperature gradient in the direction of the pulling axis of the crystal center at the solid-liquid interface of the silicon single crystal to be grown is G (° C./mm), the OSF ring region appearing inside the silicon semiconductor crystal disappears at the center of the crystal axis. When the value of F / G is defined as A0, the value of F and / or G is adjusted so that the value of F / G falls within the range of 1.2A0 or more and 1.3A0 or less. It is characterized by fostering.

Grown-in defects caused by vacancies are closely related to the cooling conditions when the crystal is cooled, and it is known that the defect density and size greatly change depending on the transit time in a cooling temperature zone in which defects are formed. Have been. Until now, the growth-in defects caused by vacancies such as COP taken into the silicon single crystal during the growth have been considered to decrease in density as the crystal defect size increases, and to decrease as the defect density increases. Had been However, when the simulation and the test by crystal growth were repeated and sincerity examination was added, the size of the crystal defect does not always become the maximum when the crystal defect density becomes the minimum,
It has been confirmed that there is some difference between the point where the density of the crystal defects is minimum and the point where the size is maximum.

When growing a single crystal, the density of grown-in defects caused by vacancies introduced into the crystal decreases as the pulling speed of the single crystal is gradually increased. When the value of F / G corresponding to the condition that the OSF ring region appearing inside the silicon semiconductor crystal disappears at the center of the crystal axis is defined as A0, according to the study of the present inventors, F / G Is 1.2
It was found that when the pulling speed corresponding to the range of A0 or more and 1.3 A0 or less showed a minimum, and then the pulling speed was further increased, the density of crystal defects gradually increased.

Therefore, if it is desired to obtain a silicon single crystal with a minimum defect density in the crystal, the silicon single crystal should be adjusted so that the value of F / G is not less than 1.2 A0 and not more than 1.3 A0. If the silicon single crystal is grown while adjusting the growth rate F and / or the value of the temperature gradient G in the direction of the pulling axis of the crystal center at the solid-liquid interface of the silicon single crystal, the vacancies caused by the vacancies taken into the silicon single crystal can be obtained. A single crystal can be grown so that the density of crystal defects is surely minimized.

If it is difficult to directly determine the temperature gradient G at the solid-liquid interface position, the melting point temperature of silicon (14
With reference to (12 ° C.), the position at which the crystal temperature decreases to a temperature (for example, 1400 ° C.) near the solid-liquid interface where the silicon semiconductor is cooled is determined by a temperature gradient G ( C / mm), and the value of F / G can be obtained. That is, from 1400 ° C to 1
The value of F / G is obtained by approximating the temperature gradient between 412 ° C., and the value of F and / or G is adjusted based on this value to grow a silicon single crystal.

The third method of manufacturing a silicon single crystal according to the present invention is directed to a method of manufacturing a silicon single crystal using the Czochralski method, wherein the size of a grown-in defect caused by a vacancy introduced into the inside of the crystal is determined. , The growth rate of the silicon single crystal is set to F (mm / min),
Given that the temperature gradient in the direction of the pulling axis of the crystal center at the solid-liquid interface of the silicon single crystal to be grown is G (° C./mm), the OSF ring region appearing inside the silicon semiconductor crystal disappears at the center of the crystal axis. When the value of F / G is defined as A0, the value of F and / or G is adjusted so that the value of F / G is in the range of 1.3A0 or more and 1.4A0 or less. It is characterized by fostering.

The size of a grown-in defect caused by vacancies introduced into the crystal during the growth of the single crystal becomes larger as the pulling speed of the single crystal is gradually increased, contrary to the density. According to the study of the present inventor, the maximum value is shown at the pulling speed corresponding to the range where the value of F / G is 1.3A0 or more and 1.4A0 or less using the value of A0 described above, Thereafter, if the pulling speed was further increased, it was found that this time, the tendency to gradually decrease was observed. Therefore, the value of F / G is 1.3.
By adjusting the growth rate F of the silicon single crystal and / or the temperature gradient G in the pulling axis direction of the crystal center at the solid-liquid interface of the silicon single crystal so as to be in the range of A0 or more and 1.4A0 or less, It is possible to grow a single crystal in which the size of crystal defects caused by vacancies taken into the single crystal is substantially maximal.

Further, the fourth method of manufacturing a silicon single crystal according to the present invention is directed to a method of manufacturing a silicon single crystal using the Czochralski method, wherein a size of a grown-in defect caused by a hole introduced into the crystal is reduced. Is set to a desired value, the growth rate of the silicon single crystal is set to F (mm / mi).
n), assuming that the temperature gradient in the direction of the pulling axis of the crystal center at the solid-liquid interface of the silicon single crystal to be grown is G (° C./mm), the OSF ring region appearing inside the silicon semiconductor crystal disappears at the center of the crystal axis. The value of F / G corresponding to the condition
When the value is set to 0, the silicon single crystal is grown by adjusting the values of F and / or G within a range where the value of F / G is 1.2 A0 or less.

As described above, a vacancy-type crystal defect such as COP causes the growth rate of a silicon single crystal to be F (mm / mi).
n) changing the temperature gradient in the direction of the pulling axis of the crystal center at the solid-liquid interface of the silicon single crystal to be grown by G (° C./mm) to obtain the minimum point and size if the density of crystal defects Then, it turned out that it changes with the maximum point. And by gradually increasing the lifting speed,
The density of the crystal defects decreases and the size increases, and after passing through the minimum point or the maximum point, the density of the crystal defects increases and the size gradually decreases.

However, in the change in the density and size of these crystal defects, the change in the density and size remarkably appears because the value of F / G when growing a silicon single crystal using the above-mentioned A0 is large. This is the case where the value is in the range of 1.2A0 or less. If a silicon single crystal having a desired crystal defect is grown by adjusting the temperature conditions and the crystal growth rate brought during the crystal growth, the F
The growth of the silicon single crystal by adjusting the operating conditions such as the pulling speed under the condition that the value of / G is 1.2 A0 or less causes a large change in the density and size of the defects, so that the efficiency is improved. Can be found under the silicon single crystal manufacturing conditions required by the method. At this time, the lower limit value of F / G is set to 1.0A0. That is, appropriate operating conditions may be determined in a range where the value of F / G is 1.0A0 or more and 1.2A0 or less. By growing a silicon single crystal by using such a manufacturing method, it is possible to obtain a desired value of the grown-in defect, and to appropriately and widely produce a silicon single crystal having a crystal quality according to a request. Will be able to

Next, the silicon single crystal wafer according to the present invention is manufactured using the silicon single crystal grown by the method of the present invention, and the size of the crystal defects existing in the silicon single crystal wafer is zero. It is characterized in that the density of crystal defects caused by vacancies of 0.05 μm or more is 3 × 10 ⁵ / cm ³ or less.

According to the method for manufacturing a silicon single crystal of the present invention, specifically, the size existing inside the crystal is 0.05%.
The crystal defect density due to pores of μm or more is 3 × 10 ⁵ / c
It is possible to obtain a high-quality silicon single crystal of m ³ or less. Therefore, by using such a silicon single crystal, it is possible to obtain a silicon single crystal wafer suitable as a material for a semiconductor element substrate, in which defects existing in the wafer surface layer are suppressed as much as possible.

The method for designing a silicon single crystal manufacturing apparatus according to the present invention is a method for designing a silicon single crystal manufacturing apparatus by the Czochralski method, which includes operating conditions for growing a silicon single crystal and the inside of a growth furnace. Temperature conditions are input to a computer as data, and the size and density of the grown-in defects caused by vacancies introduced into the crystal, and the cooling temperature atmosphere of the silicon single crystal formed inside the growth furnace of the silicon single crystal manufacturing apparatus Is determined by a simulation using an electronic computer, and based on the simulation result, the size and density of the grown-in defect caused by vacancies introduced into the crystal are set to desired values.
The temperature distribution inside the growth furnace is designed.

As described above, the crystal defects introduced into the crystal during the growth of the silicon single crystal depend on the operating conditions such as the pulling speed of the single crystal and the cooling heat history when the grown crystal is cooled. Size and density are affected. Therefore, in order to grow a silicon single crystal having a desired crystal quality, it is necessary to consider a temperature distribution inside a growth furnace of a semiconductor single crystal growing apparatus for growing a silicon single crystal. However, if the furnace internal structure to be placed inside the growth furnace is to be newly designed or designed for specification change,
Obtaining a silicon single crystal with the desired quality while actually fabricating the furnace internals in various modes and repeating the pull-up test requires enormous labor and time, and is extremely inefficient. .

Therefore, when examining the furnace internal structure constituting the inside of the growth furnace of the silicon single crystal manufacturing apparatus, simulation was performed to determine the relationship between the temperature atmosphere formed in the growth furnace and the crystal defects caused in the growth single crystal. If the relationship is determined numerically and the arrangement, shape, material, etc. of the furnace internals are determined based on the results, more efficient and reliable growth of a silicon single crystal having a desired crystal quality can be achieved. It is possible to design a silicon single crystal manufacturing apparatus capable of performing the above.

In particular, recently, a large-sized CZ silicon single crystal manufacturing apparatus for growing a silicon single crystal having a diameter of more than 300 mm is being developed. However, since it becomes more difficult and the internal structure of the furnace itself becomes expensive, once it fails, the mental damage to the designer as well as the economic loss is considerable. In terms of reducing such a risk, a more appropriate silicon single crystal manufacturing apparatus can be easily obtained by using the design method for manufacturing a silicon single crystal manufacturing apparatus according to the present invention.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
This will be described with reference to the accompanying drawings. A specific example of the method for producing a silicon single crystal according to the present invention is as follows. First,
In order to obtain the thermal history applied to the silicon single crystal inside the growth furnace, the temperature distribution inside the silicon single crystal manufacturing apparatus growth furnace is calculated by comprehensive heat transfer analysis. In this embodiment, in order to obtain the temperature distribution inside the growth furnace, a UCL (Universi
ty of Catholic Lou vain), a comprehensive heat transfer analysis program FEMAG (Reference: Int. J. Heat Mass
Using Transfer, volume 33 (1990) 1849), the heat distribution in the growth furnace is simulated to find the temperature gradient in the growth axis direction of the crystal center during crystal growth.

The computer program for performing the comprehensive heat transfer analysis includes a comprehensive heat transfer analysis program FEM.
In addition to AG, MIT (Massachusetts Institute of Tec
hnology) developed ITCM (Int. J. NumericalMe
thods in Engineering, volume 30 (1990) 133), and similar simulations can be performed.

After the temperature distribution generated in the crystal is obtained by these simulations, the temperature distribution data of the single crystal at the time of growth calculated by the crystal growth of the silicon single crystal and the above-mentioned comprehensive heat transfer analysis is used as a defect. The data is input to a formation simulation program, and the size and density of crystal defects caused by vacancies formed inside the single crystal are calculated according to pulling conditions. In the present embodiment, when simulating the size and density of crystal defects caused by vacancies formed inside a silicon single crystal, the DE developed by MIT was used.
FGEN (J. Electrochemical Soc., Volume 146 (199
0) 2300).

From these simulations, based on the operating conditions of the silicon single crystal having the desired crystal defects and the crystal temperature given to the grown crystal, the arrangement, structure or material of the furnace internal structure arranged inside the growing furnace is determined. Consider, select and decide. Then, a silicon single crystal is grown using the silicon single crystal manufacturing apparatus having the calculated operating conditions and temperature distribution.

FIG. 1 is a schematic cross-sectional view showing one embodiment of a silicon single crystal manufacturing apparatus in which an in-furnace structure is arranged inside a growth furnace based on the above simulation results. In the growth furnace 1 of the silicon single crystal manufacturing apparatus 100, there is a crucible having a quartz crucible inside and a graphite crucible outside to protect the quartz crucible in which the silicon melt 10 is housed. Are located. Further, a heater 6 for heating and melting the polycrystalline silicon lump material accommodated in the crucible 7 and holding it as a silicon melt 10 is provided around the outer periphery of the crucible 7. The temperature of the silicon melt 10 is adjusted to a desired value by adjusting the power supplied to the heater 6 to grow the silicon single crystal 8.

Further, between the heater 6 and the growth furnace 1,
A heat insulating material 5 is provided to protect the furnace wall of the metal growth furnace 1 and efficiently keep the inside of the growth furnace 1 warm. The crucible 7 containing the silicon melt 10 is a crucible support shaft 1.
The crucible shaft drive mechanism (not shown) is disposed at the approximate center of the growing furnace 1 and is attached to the lower end of the crucible support shaft 14 so as to be vertically movable and rotatable. On the other hand, an upper furnace internal structure 9 is provided above the crucible 7 containing the silicon melt 10 so as to surround the pulled silicon single crystal 8. The upper furnace internal structure 9 is made of metal or graphite, and has a silicon single crystal 8.
Is adjusted to a desired value to grow a silicon single crystal.

In the lower part of the growth furnace 1, it is necessary to grow the silicon single crystal 8 while discharging the evaporate from the silicon melt 10 to the outside of the growth furnace 1 when growing the silicon single crystal 8. Therefore, an exhaust gas pipe 12 for exhausting an inert gas such as an argon (Ar) gas refluxing into the growth furnace 1, and discharging the inert gas to the outside of the growth furnace 1 by controlling the pressure inside the growth furnace 1. For controlling the internal pressure of the furnace. When growing the silicon single crystal 8, the pressure inside the growing furnace 1 is set to a desired value by the furnace pressure control device 4.

Further, a wire winding mechanism (not shown) for unwinding or winding up a pulling wire 9 for pulling up the silicon single crystal 8 is provided at an upper portion of the growth furnace 1. A seed holder 13 for holding the seed crystal 2 is provided at the tip of the pulling wire 9 unwound from the wire winding mechanism. Below the silicon single crystal 8
To foster. Note that a gas introduction pipe 1 for introducing an inert gas into the growth furnace 1 is provided above the growth furnace 1.
1, a desired amount of inert gas can be fed into the growth furnace 1 by the gas flow control device 3 provided on the gas introduction pipe 11 in accordance with the growth conditions of the silicon single crystal 8. Have been.

Next, a method for growing a silicon single crystal by the CZ method using the above apparatus will be described. First, a polycrystalline silicon lump is charged into a crucible 7 installed inside a growth furnace 1 of a silicon single crystal manufacturing apparatus 100, and after filling the inside of the growth furnace 7 with an inert gas, a heating heater 6 placed around the crucible 7 is used. By supplying power, the melting point of silicon, 14
The silicon melt 10 is obtained by heating the polycrystalline silicon mass to 20 ° C. or higher.

When all the polycrystalline silicon blocks in the crucible 7 have become the silicon melt 10, the melt temperature is stabilized at a temperature suitable for the growth of the silicon single crystal 8, and the pulling wire 9 is unwound. The tip of the seed crystal 2 is brought into close contact with the surface of the silicon melt 10, and the crucible 7 and the seed crystal 2 are gently pulled up while rotating them in opposite directions, and the neck portion 8 a and the enlarged diameter portion 8 b of the silicon single crystal 8 are separated. Form. After that, when the diameter of the enlarged diameter portion 8b of the silicon single crystal 8 reaches a desired value, the pulling speed of the silicon single crystal 8 and the temperature of the silicon melt are adjusted, and the process for forming the single crystal constant diameter portion 8c is started. Transition.

In the step of forming the constant diameter portion 8c of the silicon single crystal 8, the winding speed of the pulling wire 9 is adjusted, and the pulling wire 9 is gradually wound so that the growth speed of the single crystal obtained by the above simulation is obtained. Then, a constant diameter portion 8c of the silicon single crystal 8 is formed. by this,
The size and density of crystal defects introduced into constant diameter portion 8c of silicon single crystal 8 are set to desired values.

Then, after the constant diameter portion 8c is pulled up to the required length, the pulling speed of the silicon single crystal 8 and the temperature of the silicon melt are changed again, and the process shifts to the step of forming a single crystal reduced diameter portion (not shown). Then, the diameter of the silicon single crystal 8 is gradually reduced to separate the silicon single crystal 8 from the silicon melt 10.
After the silicon single crystal 8 is separated from the silicon melt 10, the silicon single crystal 8 is gently waited for the single crystal to cool to around room temperature above the growth furnace 1, and finally the silicon single crystal 8 is taken out of the growth furnace 1 to finish the growth. .

When a silicon single crystal wafer is obtained from the silicon single crystal 8, the silicon single crystal 8 is taken out from the growth furnace 1 of the silicon single crystal manufacturing apparatus 100, and then sliced into a wafer by a wire saw or the like. Then, a silicon single crystal wafer is formed through each of the steps of chamfering, lapping, etching, and mirror polishing. Thereafter, the silicon single crystal wafer may be placed in a heat treatment furnace and subjected to a heat treatment at a high temperature in order to further eliminate crystal defects existing on the wafer surface layer.

In performing a simulation, an error may occur in the calculated value depending on the value input to the computer. In such a case, as a matter of course, by appropriately pulling up the silicon single crystal and confirming the quality, and then correcting the simulation result, it is possible to find an appropriate operating condition and crystal cooling atmosphere.

As described above, the specific example of the present invention has been described with reference to the example of growing a silicon single crystal by the CZ method, but the present invention is not limited to this. For example, the seed crystal used for growing a silicon single crystal and the method for producing a silicon single crystal according to the present invention include a MCZ method (Magnetic Field Applied) for growing a single crystal while applying a magnetic field to a silicon melt.
Naturally, it can also be applied to the production of silicon single crystals using the Czochralski method (magnetic field pulling method).

[0049]

EXAMPLES Experiments performed to confirm the effects of the present invention will be described below. (Example 1) Using the apparatus 100 shown in FIG. 1, in order to find the operating conditions at which the density of the grown-in defects caused by vacancies observed as COP is minimized, necessary conditions were input and the following simulation was performed. Note that a cylindrical graphite cooling cylinder is used as the upper furnace internal structure 9 to enhance the crystal heat retaining effect. First, when a silicon single crystal is grown, the total heat transfer analysis program FEMAG is used to calculate the cooling heat history of the crystal brought during the growth of the single crystal. Enter the data such as the layout and composition of the furnace internals such as
When a silicon single crystal having a diameter of 200 mm was pulled from a crucible filled with 100 kg of silicon melt using a 0 cm crucible, the relationship between the temperature distribution in the pulling axis direction of the crystal center and the crystal growth rate (pulling rate) was determined. .

Next, the relationship between the temperature distribution in the direction of the pulling axis of the crystal center and the crystal growth rate (pulling rate) obtained from this simulation was evaluated by simulating the crystal defects formed inside the crystal during silicon single crystal growth.・ I entered the program and analyzed it. In this embodiment, analysis is performed using DEFGEN developed by MIT as a computer simulation program for simulating crystal defects formed during single crystal growth. DEF using the apparatus 100 of FIG. 1
FIG. 2 shows the result of analysis of crystal defects introduced into the silicon single crystal by GEN. FIG. 2 is a graph showing, for each pulling speed of the silicon single crystal, the abscissa plotting the size of the grown-in defects caused by vacancies, and the ordinate plotting the same density, and the distribution of each is shown as a graph.

In the prediction result of FIG.
Looking at the relationship between the defect density of μm or more and the crystal pulling speed, the relationship is as shown in FIG. According to the results shown in FIG. 3, when the pulling speed is changed from a low speed of 0.5 mm / min to a high speed of 1.3 mm / min, the defect density temporarily decreases as the pulling speed is increased. It can be seen that the vicinity where the pulling speed is 0.7 mm / min is minimized, and this time it follows a tendency to gradually increase. Also, from the graph of FIG.
It can also be confirmed that the change in the defect density increases when the pulling speed is closer to the low speed from the vicinity of mm / min.

Therefore, using the apparatus 100 of FIG.
In order to pull up a silicon single crystal having a diameter of 200 mm while minimizing the density of vacancy-induced grown-in defects observed as P, the silicon single crystal was grown at a pulling speed of about 0.7 mm / min. It can be seen that it is preferable to produce a single crystal by adjusting the conditions. According to the result of this simulation, the defect density with a size of 0.05 μm or more at this time is 2.7 × 10 ⁵ defects / cm 2
It is expected to be ^3.

When the defect density is close to the minimum, 1
When the average temperature gradient in the pulling axis direction of the crystal center at 400 to 1412 ° C. is G, and the crystal growth rate (pulling rate) is F, the value indicated by F / G is based on the above-described simulations. O appearing inside the crystal
With the value of F / G when the SF ring area disappears at the center of the crystal axis as the reference value A0, it was calculated that the area was 1.2 to 1.3 times the value of A0.

Next, based on the above simulation results, 100 kg of polycrystalline silicon raw material was charged into a crucible having a diameter of 60 cm using the apparatus 100 shown in FIG. 1, and the raw material was melted by a heater to form a silicon single crystal having a diameter of 200 mm. The crystal was pulled up. The average pulling speed of this silicon single crystal was 0.69 mm / min. Then, a silicon wafer is produced from this silicon single crystal, and the size is 0.0
LST (Laser Sca)
ttering Tomography (infrared light scattering tomography) and compared with the simulation results,
The volume density of crystal defects was about 2.5 × 10 ⁵ / cm ³ , and a silicon single crystal having a crystal quality close to that of a simulation could be obtained.

(Example 2) The relationship between the typical defect size and the pulling speed of the silicon single crystal by the apparatus of FIG. 1 was obtained based on the simulation result of FIG. Here, the typical defect size refers to the peak value of the defect size shown on the horizontal axis with respect to each pulling speed in the graph shown in FIG. 2, and the relationship between this value and the pulling speed is shown in FIG. Was.

According to the results shown in FIG. 4, the lifting speed is 0.5 m
When the speed is changed from a low speed of m / min to 1.3 mm / min, the size of the vacancy-induced grown-in defect increases rapidly as the pulling speed is increased, and the pulling speed becomes 0.8.
The maximum appears in the vicinity of 5 mm / min. Then, when the pulling speed is further increased beyond 0.85 mm / min, it turns out that this time, the size of the defect is gradually reduced and the defect size is gradually reduced. In addition, comparing the results of FIG. 4 and FIG. 3, the pulling speed at which the density of the grown-in defect caused by vacancies introduced during the growth of the silicon single crystal is minimized,
It can be understood that the pulling speed at which the size indicates the maximum is not always the same, and there is a difference in the operating conditions indicating the extreme values of each other.

In the second embodiment, at a pulling speed of 0.85 mm / min, where the defect size shows a maximum, 1400
When the average temperature gradient of the crystal center at 1412 ° C. in the direction of the pulling axis was G, and the crystal growth rate (pulling rate) was F, the F / G was found to be 1.3 to 1.4 times A0. It was found that it belongs to the region of.

Further, based on these results, in order to more easily adjust the size and density of the vacancy-induced grown-in defects, the value of F / G must be reduced to a value not more than 1.2 times A0. It is understood that it is preferable to grow a silicon single crystal by adjusting the conditions and the temperature environment inside the growth furnace. Particularly, when the pulling speed is selected so as to reduce the size of the crystal defects, according to the graph of FIG.
Rather than using a high-speed pulling speed of at least min to reduce the defect size, selecting operating conditions at which the defect size has a desired value at a pulling speed of 0.7 mm / min or less increases the operating conditions. The defect size can be adjusted without changing it.

Based on the above results, the average lifting speed was set to 0.85 m using the apparatus 100 of FIG.
m / min to adjust the operating conditions to 200 mm / min.
mm single crystal silicon was grown. Then, the single crystal is processed into a silicon wafer, and the distribution of crystal defect sizes having a size of 0.05 μm or more is determined by TEM (Transmission).
Electron Microscopy (transmission electron microscope) confirmed that COP having a size of about 0.15 μm was most frequently observed.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of an apparatus for manufacturing a silicon single crystal.

FIG. 2 is a diagram showing the relationship between the size and density of vacancy-induced glow-in defects at various pulling speeds of a silicon single crystal, obtained from computer simulation results of crystal defects formed during single crystal growth.

FIG. 3 is a graph showing the relationship between the density of defects having a size of 0.05 μm or more and the pulling speed, which is obtained from the diagram of FIG. 2;

FIG. 4 is a graph showing a relationship between a typical defect size obtained from the diagram of FIG. 2 and a pulling speed of a silicon single crystal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Growth furnace 5 Heat insulating material 6 Heater 8 Silicon single crystal 9 Upper furnace internal structure 100 Silicon single crystal manufacturing apparatus

Claims (9)

[Claims] 1. A method for producing a silicon single crystal using the Czochralski method, comprising: inputting operating conditions for growing a silicon single crystal and temperature conditions inside a growth furnace as data to an electronic computer; The relationship between the size and density of the grown-in defect caused by the introduced vacancies and the growth rate of the silicon single crystal was determined by a simulation using an electronic computer. Growing a silicon single crystal by selecting a growth rate so that the size and density of the grown-in defect become desired values. 2. The relationship between the size and density of the vacancy-induced grown-in defects and the growth rate of a silicon single crystal is determined by a simulation using an electronic computer, and is introduced into the crystal based on the simulation result. 2. The method for producing a silicon single crystal according to claim 1, wherein the silicon single crystal is grown at a growth rate at which the density of the vacancy-induced crystal defects is substantially minimized. 3. The relationship between the size and density of the vacancy-induced grown-in defects and the growth rate of a silicon single crystal is determined by simulation using an electronic computer, and is introduced into the crystal based on the simulation result. 2. The method for producing a silicon single crystal according to claim 1, wherein the silicon single crystal is grown at a growth rate at which the size of the vacancy-induced grown-in defect becomes substantially maximum. 4. A method for producing a silicon single crystal by the Czochralski method, wherein the growth rate of the silicon single crystal is set to F (mm) in order to substantially minimize the density of a grown-in defect caused by vacancies introduced into the inside of the crystal. / Min), and the temperature gradient in the pulling axis direction of the crystal center at the solid-liquid interface of the silicon single crystal to be grown is represented by G
(° C./mm), when the value of F / G corresponding to the condition that the OSF ring region appearing inside the silicon semiconductor crystal disappears at the center of the crystal axis is defined as A 0, the value of F / G is 1. A method for producing a silicon single crystal, wherein a silicon single crystal is grown by adjusting the values of F and / or G so as to be in a range of 2A0 or more and 1.3A0 or less. 5. The method of manufacturing a silicon single crystal according to the Czochralski method, wherein the growth rate of the silicon single crystal is set to F (mm) in order to substantially maximize the size of a grown-in defect caused by a hole introduced into the crystal. / Min), and the temperature gradient in the pulling axis direction of the crystal center at the solid-liquid interface of the silicon single crystal to be grown is represented by G
(° C./mm), when the value of F / G corresponding to the condition that the OSF ring region appearing inside the silicon semiconductor crystal disappears at the center of the crystal axis is defined as A 0, the value of F / G is 1. A method for producing a silicon single crystal, characterized in that a silicon single crystal is grown by adjusting the values of F and / or G so as to be in a range of 3A0 or more and 1.4A0 or less. 6. A method for producing a silicon single crystal by the Czochralski method, wherein the growth rate of the silicon single crystal is set to F ( mm / min), and the temperature gradient in the pulling axis direction of the crystal center at the solid-liquid interface of the silicon single crystal to be grown is G (° C./mm), and the OSF ring region appearing inside the silicon semiconductor crystal is the center of the crystal axis. When the value of F / G corresponding to the condition that disappears in step is defined as A0, the F / G is set within a range of 1.2A0 or less.
And / or adjusting the value of G to grow a silicon single crystal. 7. The temperature gradient G (° C./mm) of the silicon single crystal pulled from the silicon melt in the pulling axis direction of the crystal center at the solid-liquid interface is changed from 1400 ° C. to 14 ° C.
The value of F / G is obtained by approximating an average temperature gradient up to 12 ° C., and the value of F and / or G is adjusted based on this value to grow a silicon single crystal. Item 7. The method for producing a silicon single crystal according to any one of Items 4 to 6. 8. A method using a silicon single crystal grown by the method according to any one of claims 1 to 7,
Among the crystal defects present in the silicon single crystal wafer,
A silicon single crystal wafer, wherein the density of crystal defects caused by the holes having a size of 0.05 μm or more is 3 × 10 ⁵ / cm ³ or less. 9. A method for designing a silicon single crystal manufacturing apparatus by the Czochralski method, comprising: inputting operating conditions for growing a silicon single crystal and temperature conditions inside a growing furnace as data to an electronic computer; The relationship between the size and density of the vacancy-induced grown-in defects introduced into the silicon single crystal manufacturing apparatus and the cooling temperature atmosphere of the silicon single crystal formed inside the growth furnace of the silicon single crystal manufacturing apparatus was determined by simulation using an electronic computer. Based on the simulation result, a temperature distribution inside the growth furnace is designed so that the size and density of the vacancy-induced grown-in defects introduced into the crystal are set to desired values. Design method for single crystal manufacturing equipment.