JP3147069B2 - Single crystal growing method, single crystal grown using the method, and single crystal wafer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for growing a single crystal, a single crystal grown using the method, and a single crystal wafer, and more particularly, to a silicon single crystal with a low defect density used as a semiconductor material. A single crystal growing method for growing
Furthermore, the present invention relates to a single crystal grown using the method and a single crystal wafer.

[0002]

2. Description of the Related Art In a silicon single crystal pulled by the Czochralski method (hereinafter referred to as CZ method), defects generally called infrared scatterers (COP, FPD) and dislocation clusters are generated. These defects are not newly formed in the crystal due to heat treatment in the subsequent device manufacturing process, but are already formed during crystal pulling, and are also called grown-in defects .

FIG. 1 is a schematic diagram showing a general relationship between a pulling speed and a position where a crystal defect is generated at the time of growing a single crystal. As shown in FIG. 1, oxidation-induced stacking fault (OSF: Oxidation-induced stacking fault), which is a kind of heat treatment-induced defect.
Inside the ring region of the Stacking Fault, there are infrared scatterers 2 of the grown-in defects observed in the evaluation after crystal growth.
1 is detected, a defect called a dislocation cluster 24 among grown-in defects is detected outside the ring region, and a defect-free region 23 exists outside the stacking fault ring (R-OSF) 22. I do. The diameter D of the grown-in defect ring in the drawing indicates the diameter of the region where the infrared scatterer 21 detected inside the stacking defect ring 22 is generated.
The region where the stacking fault ring 22 occurs depends on the pulling speed during the growth of the single crystal. As the pulling speed is reduced, the region where the stacking fault ring 22 appears contracts from the outside to the inside of the crystal. To go. See Defect Control in Semiconductor (Elsevier Sci.
ence Publishers BV) (1990), M. Hasebe etc. p.157
It is described in.

In recent years, as the temperature of the semiconductor device manufacturing process has been lowered and the grown single crystal has been reduced in oxygen, adverse effects on the device due to oxidation-induced stacking faults have been suppressed. Deterioration of device characteristics has become less of a problem.

On the other hand, a grown-in defect existing inside the stacking fault ring has a gate oxide film integrity (GO).
In order to adversely affect I), the growth-in
Reducing the density of defects has recently become an important issue, and various techniques have been proposed.

[0006] For example, techniques such as "growing a single crystal pulling apparatus inherent limitations pulling rate V _MAX 80% ~60% of the pulling speed with respect to" is disclosed in JP-A 9-202690 JP (Document 1) And JP-A-7-2
No. 57991 (Literature 2) states that "the limit lifting speed V
By growing a single crystal below _MAX (= f × G),
A single crystal wafer having no stacking fault ring can be obtained (f: proportional coefficient, G: axial temperature gradient).

These prior arts reduce the diameter of the stacking fault ring depending on the pulling speed without reducing the production efficiency of the single crystal (that is, without greatly reducing the pulling speed of the single crystal). This is a technique intended to effectively use a defect-free region existing outside the ring.

[0008]

The technique described in each of Documents 1 and 2 has a pulling speed V (= V _MAX × 60 to 80% (Reference 1)) which is equal to or lower than the limit pulling speed V _MAX. And growing a single crystal. The growth rate V _gr of the single crystal can be simply expressed by the following equation (1).

[0009]

[Number 1] _{V gr = 1 / Lρ [K} S (dT / dx) S -K L (dT
/ Dx) _L] V _gr: Growth rate L: heat of solidification [rho: crystal density K _S: thermal conductivity of the crystal (dT / dx) _S: the temperature gradient in the crystal K _L: thermal conductivity of the melt (dT / Dx) _L : temperature gradient in the melt The limit pulling speed V _MAX is the case where there is no heat input from the melt, so the heat transfer term from the melt is deleted from equation (1), and Is represented as

[0010]

V _MAX = 1 / Lρ [K _S (dT / dx) _S ] As can be seen from the equation (2), and similarly to the technique disclosed in Reference 2, in order to obtain the limit pulling speed V _MAX , The value of the temperature gradient in the crystal is required. Conversely, if the value of the temperature gradient is not known, the limit raising speed _VMAX cannot be obtained.

However, since the value of the temperature gradient changes every moment depending on the amount of the raw material melt remaining as the crystal grows, the position of the crucible filled with the melt, and the like, it is empirical. It is also very difficult to find. further,
In the actual crystal growth, there is no ideal limit pulling speed V _MAX as shown by the equation (2), and the difference between the mechanical center between the crystal rotation and the crucible rotation and the difference between the rotation center and the heat distribution center. Even if the term of K _L (dT / dx) _L in Equation 1 is not zero due to various factors such as the inclination of the single crystal growing apparatus from the horizontal, etc., that is, the theoretical limit pulling speed V _MAX Even if the single crystal is pulled at a speed V ₁ (<V _MAX ) that does not reach the maximum, the single crystal may be twisted in a spiral shape and deformed, making it impossible to continue crystal growth. In other words, the worker determines the lifting speed at the point of time when it becomes impossible to continue as the (apparent) limit lifting speed, and determines the true limit lifting speed V _MAX from the worker's sensitivity. It is difficult.

Further, as described above, factors such as the deviation of the mechanical center between the crystal rotation and the crucible rotation, the deviation between the rotation center and the heat distribution center, and the inclination of the single crystal growing apparatus from the horizontal are also included. Since the critical pulling speed changes depending on the difference in the configuration of the graphite structure called a hot zone in the crystal growing furnace, it is difficult to uniquely determine the critical pulling speed specific to each pulling device. That is,
It is practically impossible to determine the “limit lifting speed inherent to the lifting device” described in Document 1.

Therefore, it is impossible to control the diameter of the stacking fault ring in the above-described conventional technology, and it is difficult to reduce the density of grown-in defects existing inside the stacking fault ring in a single crystal. Met.

The present invention has been made in view of the above problems, and a method of growing a single crystal capable of reducing the density of grown-in defects in a single crystal by controlling the diameter of the stacking fault ring. It is another object of the present invention to provide a single crystal grown using the single crystal growing method and a single crystal wafer.

[0015]

When the pulling rate of the means for solving the problems and their effects Single crystal approaches the true limit pulling rate V _MAX, i.e. equation 1 K _{L (dT} / dx) _L sections approaches zero, The plane shape orthogonal to the crystal pulling direction during the growth is shifted from a perfect circle shape. Figure 2 is a schematic diagram shows the cut surface 1 of a single crystal which is perpendicular to the crystal pulling direction, pull
When the displaced single crystal grows without dislocations, pulling is performed at four places on the outer peripheral surface 2 of the single crystal pulled as shown in the figure.
A protruding habit line extending parallel to the ascending direction appears , and the shape of the cut surface 1 of the single crystal depends on the growth rate of the crystal orientation.
Is transformed from a perfect circle to a square. In the figure, D _MAX ,
D _MIN indicates the maximum diameter and the minimum diameter, respectively.

The present inventors have conducted various tests / analysis focusing on the crystal plane shape deviating from the perfect circular shape. This test /
As a result of the analysis, the deviation rate of the crystal plane shape from the perfect circular shape (hereinafter, referred to as crystal deformation rate), that is, (maximum diameter D _MAX -minimum diameter D _MIN ) / minimum diameter in a plane orthogonal to the crystal pulling direction. It has been found that a strong correlation is established between D _MIN and the diameter of the stacking fault ring. This makes it possible to set the diameter of the stacking fault ring to a desired value by using the crystal deformation rate as an index.

FIG. 3 is a graph showing the relationship between the crystal deformation rate and the diameter of the stacking fault ring. In the figure, black circles indicate data obtained from a crystal having a diameter of 6 inches, and open circles, black triangles, and white squares indicate data obtained from a crystal having a diameter of 8 inches. The crystals indicated by black circles and white circles were grown using the same pulling device,
The lifting devices used for the black circle, the black triangle, and the white square are different from each other. However, the difference in the pulling apparatus here includes a difference in the configuration of a graphite structure called a hot zone in the crystal growing furnace.

The data shown in FIG. 3 is obtained from a substantially central portion of the crystal (a position approximately 400 mm to 600 mm from the top of the crystal body). As can be seen from FIG. 3, regardless of the crystal diameter and the pulling apparatus, the diameter of the stacking fault ring is located at the outermost periphery of the pulled crystal when the crystal deformation rate becomes 1.5% or more. Although not shown, this relationship was similarly established at the top and bottom of the crystal.

Samples marked with an “x” in a white circle indicate that the crystal was transformed from a columnar shape into a quadrangular prism shape or a polygonal prism shape, so that it was impossible to continue crystal growth. The samples marked with “x” in the white square indicate that the crystal growth was impossible due to the helical twist deformation of the crystal.

FIG. 4 is a graph showing the relationship between the crystal deformation rate of the samples shown in FIG. 3 and the pulling speed at the time of growing the samples. As can be seen from FIGS. 3 and 4, the outermost peripheral position of the stacking fault ring in the grown crystal cannot be uniquely determined from the limit pulling speed in the sense that crystal growth cannot be continued. However, when the crystal deformation rate becomes 1.5% or more, the stacking fault ring is located at the outermost periphery of the pulled crystal regardless of the crystal diameter and the pulling apparatus, and the crystal deformation rate is obtained as an index. By multiplying the pulling rate by a predetermined coefficient α, a crystal having a desired stacking fault ring diameter can be obtained. On the other hand, if the crystal deformation ratio exceeds 2.0%, the irregularities of the surface shape perpendicular to the crystal pulling direction become too large, and the rounding loss for obtaining a predetermined wafer diameter is undesirably large.

According to the above method, the crystal deformation rate ranges from 1.5 to 2.
By setting a profile of the crystal pulling speed so as to be 0% and multiplying a predetermined coefficient at each crystal position to obtain a desired stacking fault ring diameter, the diameter of the stacking fault ring can be controlled. .

That is, the single crystal growing method (1) according to the present invention is a method for growing a single crystal by dipping a seed crystal in a melt in a crucible and then pulling the seed crystal to grow the single crystal. The pulling speed V _op such that the crystal deformation rate expressed by (maximum diameter−minimum diameter) / minimum diameter in a plane perpendicular to the pulling direction is a predetermined target deformation rate in the range of 1.5 to 2.0%. Is calculated in advance, and the target pulling speed V at the time of actual raising is calculated as V = V _op × α
Set (α ≦ 0.8), and pull at the time of actual development
Control the up speed V _r can within the range of V _r = V ± 0.4V
And the average pulling speed within a predetermined time from the start of crystal growth
It is characterized in that the degree V _ac is controlled within a range of V _ac = V ± 0.02V .

According to the single crystal growing method (1), the predetermined coefficient α (≦ 0) is set for the pulling speed V _{op at} which the crystal deformation ratio becomes an appropriate value (1.5 to 2.0%). .8), the diameter of the stacking fault ring can be set to a desired value. Therefore, the diameter of the stacking fault ring can be reduced, and the defect-free region existing outside the ring can be effectively used. In addition, when growing up
Within the appropriate range of the actual lifting speed
Since the average lifting speed is also controlled within an appropriate range,
Of stacking fault ring diameter without reducing crystal production efficiency
Can be reduced.

Further, the method for growing a single crystal according to the present invention (2)
After immersing the seed crystal in the melt in the crucible,
Single crystal growing method for growing single crystal by pulling
At a plane perpendicular to the crystal pulling direction.
Crystal deformation expressed by (maximum diameter-minimum diameter) / minimum diameter
A predetermined target deformation rate in the range of 1.5 to 2.0%
Such a pulling speed V _op is calculated in advance, and the actual
The target pulling speed V at the time of formation is _defined as V = _Vop × α (α ≦
0.8), at least two levels of coefficients β ₁ ,
β ₂ (0.3 ≦ β ₁ ≦ 1.0, 0.3 ≦ β ₂ ≦ 1.0)
Target pulling speed V ₁ = V _op × β ₁ , V ₂ = V using
_op × β ₂ Grown-based on each crystal
The diameters D ₁ and D ₂ of the in-defect ring are measured, and the diameter change rate of the grown-in defect ring (D ₁ -D ₂ ) is obtained from these measurement results.
/ (Β ₁ −β ₂ ), and based on the calculation result, gr
It is characterized in that a coefficient α for setting the diameter of the own-in defect ring to a desired value is obtained.

According to the single crystal growing method (2), the crystal
Draw so that the deformation ratio is an appropriate value (1.5 to 2.0%).
The raising speed V _op is multiplied by a predetermined coefficient α (≦ 0.8).
By shifting, the diameter of the stacking fault ring is set to a desired value.
Can be Therefore, the diameter of the stacking fault ring is
To reduce the defect-free area outside the ring
It can be used. Also, at least 2
Grown using the level coefficients β ₁ and β ₂ , in order to use the diameter change rate determined from each crystal, the diameter of the grown-in defect ring becomes a desired value over the entire length of the grown crystal. Can be

Further, the method for growing a single crystal according to the present invention (3)
, In the single crystal growth method (2), by controlling the pulling rate V _r when the actual development within the V _r = V ± 0.4V, the average pulling rate within a predetermined time from the initiation of pulling-up of crystal It is characterized by controlling the V _ac in the range of V _ac = V ± 0.02 V.

According to the single crystal growing method (3), the range of the actual pulling speed during growing is set within an appropriate range.
Further, by controlling the average pulling speed in an appropriate range, the variation in the stacking fault ring diameter can be reduced without lowering the production efficiency of the single crystal.

The single crystal growing method according to the present invention (4)
Is characterized in that the coefficient α is 0.6 or less in any of the single crystal growing methods (1) to (3).

According to the single crystal growing method (4), the single crystal having a coefficient α of 0.6 or less can be grown to grow a single crystal having a particle count of substantially zero.

Further, the single crystal (1) according to the present invention is a single crystal grown by using any one of the above-mentioned single crystal growing methods (1) to (4), wherein grown-in defects have a low density. And
It is characterized by being uniformly distributed over the entire length of the grown crystal.

According to the single crystal (1), the grown-in defects have a low density and are uniformly distributed over the entire length of the grown crystal, so that the single crystal is very excellent as a semiconductor material.

Further, the single crystal wafer (1) according to the present invention
Is a single crystal wafer produced by slicing a single crystal grown using any of the above-mentioned single crystal growing methods (1) to (3) and polishing it to a mirror-like surface. The count number of particles having a size of 13 μm or more is 25 or less for a 6-inch wafer, 50 or less for an 8-inch wafer, and 100 or less for a 12-inch wafer, and the distribution of the particles is uniform over the entire length of the grown crystal. It is characterized by being targeted.

According to the single crystal wafer (1), the number of the particles is extremely small, and the distribution of the particles is uniform over the entire length of the grown crystal. Can be manufactured.

Further, the single crystal wafer (2) according to the present invention
Is a single crystal wafer produced by slicing a single crystal grown using the above single crystal growing method (4), polishing the surface to a mirror, or the like, and using a laser surface detector to measure particles of 0.13 μm or more. Is substantially zero, and the distribution of the particles is uniform over the entire length of the grown crystal.

According to the single crystal wafer (2), the count number of the particles is substantially zero, and the distribution of the particles is uniform over the entire length of the grown crystal. High quality semiconductor devices can be manufactured.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the method for growing a single crystal according to the present invention will be described below with reference to the drawings. FIG.
It is sectional drawing which showed typically an example of the single crystal pulling apparatus used for Z method, and 11 has shown the crucible in the figure.

The crucible 11 comprises a bottomed cylindrical quartz crucible 11a and a bottomed cylindrical graphite crucible 11b fitted to the outside of the quartz crucible 11a. Reference numeral 11 is supported by a support shaft 18 which rotates at a predetermined speed in the direction of arrow A in the figure. This crucible 1
1, a heater 12 of a resistance heating type,
A heat retaining cylinder 17 is arranged concentrically outside the tube 2, and the crucible 11 is filled with a melt 13 of a crystal raw material melted by the heater 12. A lifting shaft 14 made of a lifting rod or a wire is suspended from the center axis of the crucible 11.
The seed crystal 15 is attached. Also,
These members are a water-cooled chamber 1 whose pressure can be controlled.
It is contained within 9.

A method of pulling single crystal 16 using the above-described single crystal pulling apparatus will be described. First, the inside of the chamber 19 is depressurized, and then an inert gas is introduced to make the inside of the chamber 19 a depressurized inert gas atmosphere. Release sufficient gas.

Next, in the opposite direction with the same axis as the support shaft 18,
While rotating the pulling shaft 14 at a predetermined speed, the seed crystal 15 attached to the holder 14 a is lowered to be immersed in the melt 13, and the seed crystal 15 is adapted to the melt 13. A single crystal 16 is grown at the lower end of the substrate.

In general, the diameter of the single crystal 16 is directly or indirectly recognized by an optical or gravimetric sensor (not shown), and is previously determined by a control means (not shown). It is controlled so as to follow the input single crystal diameter and single crystal pulling speed profile set.

The single crystal growing method (1) according to the embodiment of the present invention will be described. 1. 1. Measure the crystal diameter with a CCD camera during crystal growth. 2. Calculate the crystal deformation rate from the measured value. By using a learning control system having a learning function, the crystal deformation rate is reduced to a target crystal deformation rate (1.5 to 1.5).
2.0%), adjust the lifting speed. From the adjustment result, the crystal deformation rate was 1.5 to 2.0%.
_4. Calculate the pulling speed V _op such that The target pulling speed V at the time of actual raising is V = V
Set to _op × α (α ≦ 0.8) The single crystal 16 is grown by using the single crystal pulling apparatus shown in FIG. 5 according to the target pulling speed V set in the above 5.

According to the single crystal growing method (1) according to the above-described embodiment, the crystal deformation rate is an appropriate value (1.5-2.
The diameter of the stacking fault ring can be set to a desired value by multiplying the pulling speed V _op to be 0%) by a predetermined coefficient α (≦ 0.8). Therefore, the diameter of the stacking fault ring can be reduced, and the defect-free region existing outside the ring can be effectively used.

Next, the single crystal growing method (2) according to the embodiment will be described. However, the single crystal growing method is
This is based on the single crystal growing method (1) according to the above embodiment. 1. 1. Measure the crystal diameter with a CCD camera during crystal growth. 2. Calculate the crystal deformation rate from the measured value. By using a learning control system having a learning function, the crystal deformation rate is reduced to a target crystal deformation rate (1.5 to 1.5).
2.0%), adjust the lifting speed. From the adjustment result, the crystal deformation rate was 1.5 to 2.0%.
_4. Calculate the pulling speed V _op such that The target pulling speed V at the time of actual raising is V = V
_op × β (0.3 ≦ β ≦ 1.0), at least 2
The target lifting speed V using the level coefficients β ₁ and β ₂
6 to set the _1, V _2. According to the set V ₁ and V ₂ , the single crystal 16 is grown using the single crystal pulling apparatus shown in FIG. Grown-in in each single crystal 16
7. Measure the diameters D ₁ and D ₂ of the defective ring. 8. From these measurement results, the diameter change rate (D ₁ −D ₂ ) / (β ₁ −β ₂ ) of the grown-in defect ring is calculated. 9. Based on the calculation result, a coefficient C for setting the diameter of the grown-in defect ring to a desired value is determined. Based on the obtained coefficient C, the target pulling speed V at the time of actual breeding is set to V = _Vop × C. According to the target pulling speed V set in the above 10, FIG.
The single crystal 16 is grown using the single crystal pulling apparatus shown in FIG.

According to the single crystal growing method (2) according to the above embodiment, the diameter change rate obtained from each crystal grown using at least two levels of coefficients β ₁ and β ₂ is used. This allows the diameter of the grown-in defect ring to have a desired value over the entire length of the grown crystal.

Next, a single crystal growing method (3) according to the embodiment will be described. However, the single crystal growing method is
Single crystal growing method (1) or (2) according to the above embodiment
The description of the same parts as in the single crystal growing method (1) according to the above embodiment is omitted.

[0046] controls the pulling rate V _r when the actual development within the V _r = V ± 0.4V, the average pulling rate V _ac within a predetermined time period from the time of initial growth of the crystal V _ac = V ±
By controlling within a range of 0.02 V, the single crystal 16 is grown using the single crystal pulling apparatus shown in FIG.

According to the single crystal growing method (3) according to the above embodiment, the actual pulling speed V during growing is
Is controlled within an appropriate range, and the average pulling speed _Vac is also controlled within an appropriate range, so that the variation width of the stacking fault ring diameter can be reduced without lowering the production efficiency of the single crystal 16. .

Further, the single crystal (1) according to the embodiment is:
A single crystal grown by using any one of the single crystal growing methods (1) to (3) according to the above-described embodiment, wherein the single crystal is grown-in.
The defects have a low density and are uniformly distributed over the entire length of the grown crystal, which makes the semiconductor material very excellent.

[0049]

Examples and Comparative Examples Hereinafter, a method for growing a single crystal according to examples will be described. Examples 1 to 4 here use the single crystal growing method (1) according to the above-described embodiment. As Comparative Examples 1 to 4, a single crystal pulling apparatus using the CZ method (see FIG. 5) was used. A case where a single crystal is pulled by a conventional method will also be described. The conditions are described below.

[Conditions Common to Examples 1 to 3 and Comparative Examples 1 and 2] Charged amount of crystal raw material: 100 kg Atmosphere in chamber 19: Ar atmosphere Ar flow rate: 100 liter / min Furnace pressure: 2660 Pa (About 20 Torr) Diameter of crucible 11: 22 inches Shape of single crystal 16 to be pulled Diameter: 8 inches Length: 1000 mm Average crystal pulling speed: 0.8 mm / min FIG. 6 shows that the crystal deformation rate is 1.5 over the entire length of the crystal. % ~
It is a graph showing the pulling rate V _op of 1.8% and became crystalline.

The crystal pulling speed V _op is set by measuring the crystal diameter with a CCD camera during crystal growth, and calculating a crystal deformation rate calculated from the measured value and a preset target deformation rate (here, 1.8%). And the actual crystal deformation rate is 1.8
% By using a learning control system having a learning function of changing the pulling speed so as to be a percentage.

Next, for the set lifting speed V _op ,
Any position x of the crystal position is multiplied by a constant coefficient α to obtain V
Three crystals were grown so that (x) = V _op (x) × α. The coefficient α is set to 0.8, 0.6, and 0.4, and two samples are cut at intervals of 200 mm in the crystal growth direction. One is used for crystal defect evaluation, and the other is used for stacking faults. It was used to measure the diameter of the ring.

After heat treatment in a wet oxygen atmosphere corresponding to the oxygen concentration of the crystal, selective etching is performed with a Wright solution to observe stacking faults, and the outer diameter of the stacking fault ring is measured. Of diameter. The other one is subjected to selective etching with Secco solution without heat treatment, so that the growth existing inside the stacking fault ring is removed.
Measure the area where the n-in defect occurs and gr
The diameter of the own-in defect ring. Table 1 below shows the measurement results.

[0054]

[Table 1]

As is clear from the results shown in Table 1, in Examples 1 to 3, the diameter of the stacking fault ring and the diameter of the grown-in defect ring were made substantially constant from the top to the bottom of the crystal. I have control. The variation is about 18 mm and 16 mm in Examples 1 and 2, respectively, and the variation is largely suppressed. In the third embodiment, the stacking fault ring diameter and the grown-in defect ring diameter are zero.

As Comparative Examples 1 and 2, the evaluation results of the grown-in defect ring diameter when a coefficient of 0.8 was multiplied by a standard value of the limit lifting speed based on the operator's sensitivity as in the past were as follows. It is shown in Table 2. However, Comparative Example 1 is the same as the lifting device used in Examples 1 to 3, but the lifting device used in Comparative Example 1 and Comparative Example 2 has a different structure.

[0057]

[Table 2]

As is evident from the results shown in Table 2, in the conventional method, since the essential limit pulling speed is not set, even if a certain coefficient is multiplied when the lifting device is different, A certain defect generation area cannot be obtained. In both cases of Comparative Examples 1 and 2, the uniformity in the crystal growth direction is not good.

Further, the single crystals obtained by slicing the three crystals having coefficients of 0.8, 0.6 and 0.4 respectively obtained in Examples 1 to 3 and subjecting them to mirror polishing, etc. After SC-1 cleaning of the wafer, the wafer surface was inspected by a laser surface inspection machine. The number of inspections was measured every 150 sheets. Table 3 below shows the results of counting the particles having a size of 0.13 μm or more.

[0060]

[Table 3]

As is clear from the results shown in Table 3, in each case, the number of the particles is extremely small, and the distribution of the particles is uniform over the entire length of the grown crystal. The device characteristics are good and high quality. Further, in the single crystal wafers obtained in Examples 2 and 3 (coefficient of 0.6 or less), the count number of the particles is substantially zero.

Next, Example 4 in which the single crystal growing method (2) according to the above embodiment is used will be described. Of the three crystals obtained in Examples 1 to 3, a coefficient of 0.8
(Example 1) and an average diameter D in a grown-in defect ring obtained from two crystals having a coefficient of 0.6 (Example 2).
The diameter change rate (ΔDde / Δβ) was calculated from the coefficient β and the average diameter Dde using de (see Table 1).

Using this diameter change rate, an attempt was made to grow a crystal having a grown-in defect ring diameter of 100 mm.
The following calculation was performed using the average diameters of 156 mm and 76 mm when the coefficients were 0.8 and 0.6 shown in Table 1.

The rate of change in diameter of the defect generation region = (156−76) / (0.8−0.6) = 400 Therefore, the coefficient C ₁₀₀ for obtaining a crystal in which the diameter of the grown-in defect ring is 100 mm is , 76 + 400 × (C
₁₀₀ -0.6) = 100 than sought, C ₁₀₀ = 0.6
6 was obtained.

Table 4 below shows the evaluation results of the crystals grown using the pulling speed V set as V = V _op × 0.66. The evaluation was performed in the same manner as in the growth-in defect evaluation in Examples 1 to 3. As is clear from the results shown in Table 4, the results were almost 100 mm as expected.

[0066]

[Table 4]

Next, Examples 5 to 8 using the single crystal growing method (3) according to the above embodiment will be described. The conditions are described below.

[Conditions Common to Examples 5 to 8] Charged amount of crystal raw material: 100 kg Atmosphere in chamber 19: Ar atmosphere Ar flow rate: 100 L / min Furnace pressure: 2660 Pa (about 20 Torr) Diameter: 22 inches Shape of the single crystal 16 to be pulled Diameter: 8 inches Length: 1000 mm Average crystal pulling speed: 0.8 mm / min With respect to the pulling speed _Vop set in Example 1 above, for any position x of the crystal position. Multiplied by a constant coefficient of 0.8
Crystals were grown so that (x) = V _op (x) × 0.8.

In order to keep the crystal diameter at the set diameter value (8 inches), the calculated pulling speed control amount is fed back to the pulling speed _Vr in a 5-second cycle according to the deviation from the measured crystal diameter value, and the crystal is grown. Pulling speed _Vr at the time
The crystal growth was carried out by setting (x) at a fixed control width with respect to V (x) = V _op (x) × 0.8.

That is, 0.2 times higher and lower than the speed V,
The crystals were grown by giving 0.4 times, 0.6 times, and 0.8 times (Examples 5 to 8), and grown similarly to Examples 1 to 3.
The n-in defect ring diameter was measured. Table 5 below shows the measurement results.

[0071]

[Table 5]

[0072] As apparent from the results shown in Table 5, V ± 0.2V the pulling rate V _r during crystal growth or when controlled within the range of V ± 0.4V, the diameter of the defect, Was about 15 mm with respect to the crystal growth direction, but within a range of V ± 0.6 V, 32 mm, V ±
In the range of 0.8 V, it was as large as 45 mm.

When the average pulling speed _Vac for 60 minutes after the start of crystal growth was examined, V ± 0.004 V, V ± 0.020 V, V ± 0.026 V were obtained in the order of Examples 5 to 8.
V, V ± 0.033V. In order to effectively use the defect-free region, the diameter of the grown-in defect generation region is preferably set to 140 mm or less for an 8-inch crystal. For this purpose, the crystal pulling speed is an average value of V _op × C ₁₄₀ ( C ₁₄₀ =
It must be about 0.75 (see Equation 3 below). In addition, if the fluctuation of the grown-in defect area diameter is large, it is necessary to further lower the pulling speed, so that
For example, for a variation of 32 mm (Example 7), V _op × C
₁₀₈ (C ₁₀₈ = 0.68 (see Equation 4 below)), the maximum diameter of the grown-in defect ring is 140
mm or less.

A coefficient C ₁₄₀ for calculating the diameter of a grown-in defect ring to 140 mm with an 8-inch crystal is calculated based on the fourth embodiment.

[0075]

76 + 400 × (C ₁₄₀ −0.6) = 140 The diameter of a grown-in defect ring is 108 mm with an 8-inch crystal.
_Is calculated based on the fourth embodiment.

[0076]

Since Equation 4] _{76 + 400 × (C 108 -0.6} ) = 140 coefficients C that decreases would drop the production efficiency, in order to avoid set lower than necessary, as much as possible, the growth direction It is desirable to suppress the fluctuation of the diameter of the grown-in defect ring at the step. Thus, by controlling the pulling rate V _r of each control period within the range of V ± 0.4V, the variation of the average pulling rate V _ac for 60 minutes after the crystal growth starting becomes below V ± 0.020V grown- The diameter fluctuation of the in-defect ring is reduced. The coefficient C at this time is about 0.7
It becomes 2.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a general relationship between a pulling speed and a position where a crystal defect is generated during single crystal growth.

FIG. 2 is a schematic view showing a crystal plane orthogonal to a crystal pulling direction.

FIG. 3 is a graph showing a relationship between a crystal deformation rate and a stacking fault ring diameter.

FIG. 4 is a graph showing the relationship between the crystal deformation rate of the samples shown in FIG. 3 and the pulling speed at the time of growing the samples.

FIG. 5 is a cross-sectional view schematically showing a single crystal pulling apparatus used for the CZ method.

FIG. 6 shows that the crystal deformation rate is 1.5% to over the entire length of the crystal.
It is a graph showing the pulling rate V _op of 1.8% and became crystalline.

[Explanation of symbols]

1 Single crystal cut surface 2 Single crystal outer peripheral surface

Claims (7)

(57) [Claims] After immersing a seed crystal in a melt in a crucible,
In the single crystal growing method for growing a single crystal by pulling the seed crystal, a crystal deformation rate expressed by (maximum diameter−minimum diameter) / minimum diameter in a plane orthogonal to the crystal pulling direction is 1.5 to 2; The lifting speed V _op is calculated in advance so as to have a predetermined target deformation rate in a range of 0.0%,
The target pulling speed V at the time of actual raising is V = V _op ×
Set to α (α ≦ 0.8) and at the time of actual breeding
Control the pulling speed V _r in the range of V _r = V ± 0.4V
And the average pulling speed within a predetermined time from the start of crystal growth
A method for growing a single crystal, characterized in that the degree V _ac is controlled within a range of V _ac = V ± 0.02 V. 2. After immersing a seed crystal in a melt in a crucible,
Single bond for growing a single crystal by pulling up the seed crystal
In the crystal growth method, in a plane perpendicular to the crystal pulling direction
Expressed by (maximum diameter−minimum diameter) / minimum diameter
Predetermined target deformation with a crystal deformation ratio in the range of 1.5 to 2.0%
Calculate in advance the pulling speed V _op to obtain the rate ,
The target pulling speed V at the time of actual raising is V = V _op ×
When setting α (α ≦ 0.8), at least two levels of coefficients β ₁ and β ₂ (0.3 ≦ β ₁ ≦
1.0, 0.3 ≦ β ₂ ≦ 1.0) target pulling speed V ₁ = V _op × β ₁ , V ₂ = V _op × β ₂ Diameter of grown-in defect ring of each crystal grown based on
₁ and D ₂ are measured, and the diameter change rate (D ₁ −D ₂ ) / (β ₁ −β ₂ ) of the grown-in defect ring is calculated from these measurement results, and the grown-in defect is determined based on the calculation result. A method for growing a single crystal, wherein a coefficient α for setting a diameter of a ring to a desired value is obtained. 3. The pulling speed V _r during actual growth
Is controlled within the range of V _r = V ± 0.4 V, and the average pulling speed V _ac within a predetermined time from the start of crystal growth is set to V _ac = V
Claims, characterized in that the control within a range of ± 0.02 V
Item 4. The method for growing a single crystal according to Item 2 . 4. The method for growing a single crystal according to claim 1, wherein the coefficient α is 0.6 or less. 5. A single crystal grown using the method for growing a single crystal according to claim 1, wherein the single crystal is grown.
A single crystal characterized in that n-in defects have a low density and are uniformly distributed over the entire length of the grown crystal. 6. Slicing a single crystal grown using the method for growing a single crystal according to any one of claims 1 to 3,
A single crystal wafer manufactured by mirror polishing or the like, wherein the count number of particles of 0.13 μm or more by a laser surface inspection device is 25 or less for a 6-inch wafer and 50 or less for an 8-inch wafer. A single-crystal wafer having a particle size of 100 or less for a 12-inch wafer, and the distribution of the particles is uniform over the entire length of the grown crystal. 7. A single crystal wafer produced by slicing a single crystal grown by the method for growing a single crystal according to claim 4 and subjecting the single crystal to mirror polishing or the like. A single crystal wafer, wherein the number of particles of the above size is substantially zero, and the distribution of the particles is uniform over the entire length of the grown crystal.