JPH11322490A - Production of silicon single crystal wafer and silicon single crystal wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for simply producing a silicon single crystal wafer having very few defects in high productivity by inhibiting the growth of crystal defects, in particular, the growth of crystal defects in a surface layer of the wafer, and also surely removing the crystal defects by subjecting the wafer to heat treatment for a short period of time, even when crystal defects having low density are caused, in a single crystal wafer produced by a CZ (Czochralski) method. SOLUTION: The production of silicon single crystal wafer comprises: growing a silicon single crystal bar doped with nitrogen by a CZ method; slicing the silicon single crystal bar into silicon single crystal wafers; and thereafter, subjecting the wafers to heat treatment with a rapid-heating/rapid-cooling device. Thus, the objective silicon single crystal wafer is produced by this production method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called grown-in defect which is present in a crystal by doping with nitrogen when a silicon single crystal is pulled by the Czochralski method (hereinafter referred to as CZ method). A method for producing a silicon single crystal wafer from which crystal defects on a wafer surface have been removed with high productivity by reducing the size of crystal defects and applying high-temperature heat treatment to the wafer by a rapid heating / cooling device, and this method The present invention relates to a silicon single crystal wafer manufactured by the method described above.

[0002]

2. Description of the Related Art Wafers for manufacturing devices such as semiconductor integrated circuits are mainly manufactured by the Czochralski method (C
A silicon single crystal wafer grown by the Z method is used. If a crystal defect exists in such a silicon single crystal wafer, a pattern defect or the like is caused at the time of manufacturing a semiconductor device. In particular, the pattern width in recent highly integrated devices is 0.35
In such a pattern formation, the presence of a crystal defect of a size of 0.1 micron may cause a pattern defect or the like at the time of forming such a pattern. Would. Therefore, crystal defects existing in the silicon single crystal wafer must be reduced as much as possible.

In recent years, it has recently been reported that in a silicon single crystal grown by the CZ method, crystal defects introduced during crystal growth, referred to as the above-mentioned grown-in defects, are found by various measuring methods. I have. For example, in the case of a single crystal pulled at a general growth rate (for example, about 1 mm / min or more) produced at a commercial level, these crystal defects are formed in a Secco solution (K ₂ Cr ₂ O ₇ , hydrofluoric acid and water). Selectively etch the surface with a mixture of
The pits can be detected by co-etching (see Japanese Patent Application Laid-Open No. 4-192345).

It is considered that the main cause of the formation of pits is a cluster of atomic vacancies that aggregate during the production of a single crystal or an oxygen precipitate that is an aggregate of oxygen atoms mixed in from a quartz crucible. If these crystal defects are present in the surface layer (0 to 5 microns) of the wafer on which the device is formed, they become harmful defects that degrade the device characteristics.
Various methods for reducing such crystal defects have been studied.

[0005] For example, it is known that the density of the clusters of atomic vacancies can be reduced by growing the crystal at an extremely low crystal growth rate (for example, 0.4 mm / min or less). (See Japanese Patent Application Laid-Open No. 2-267195). However, it has been found that this method causes crystal defects which are considered to be dislocation loops formed by newly gathering excess interstitial silicon, significantly degrades device characteristics, and does not solve the problem. In addition, since the crystal growth rate is reduced from about 1.0 mm / min or more to 0.4 mm / min or less, the productivity of single crystals is significantly reduced and the cost is increased.

On the other hand, in order to reduce crystal defects caused by oxygen precipitates on the surface layer of the wafer, the wafer is heat-treated at a high temperature of 1100 ° C. or more, whereby oxygen in the crystals is diffused outward to dissolve the oxygen precipitates. An annihilating solution has been taken. However, in this method, the heat treatment must be performed for a long period of time, for example, 4 hours or more, and the productivity,
In addition to being disadvantageous in terms of cost, since it takes time to raise and lower the temperature of the wafer, oxygen precipitates are formed in the device forming layer during the raising and lowering of the temperature, and the intended purpose and effect are often not achieved.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and suppresses the growth of crystal defects (grown-in defects) in a silicon single crystal wafer produced by the CZ method. Even if small crystal defects occur, the method provides a method of manufacturing silicon single crystal wafers with extremely low defects in the surface layer of the wafer, with high productivity and easy production, by reliably removing them by short-time heat treatment. The main purpose is to

[0008]

In order to solve the above-mentioned problems, the invention described in claim 1 of the present invention grows a silicon single crystal rod doped with nitrogen by the Czochralski method, A method for producing a silicon single crystal wafer, characterized in that after slicing and processing into a silicon single crystal wafer, the silicon single crystal wafer is subjected to a heat treatment by a rapid heating / rapid cooling device.

As described above, when a single crystal rod is grown by the CZ method, the growth of crystal defects introduced during the crystal growth can be suppressed by doping with nitrogen. In addition, since the growth of crystal defects is suppressed, the crystal growth rate can be increased, so that the productivity of the crystal can be significantly improved.

[0010] When a wafer processed from such a nitrogen-doped silicon single crystal is subjected to a heat treatment by a rapid heating / cooling device, oxygen and nitrogen on the wafer surface are diffused outward, and the crystal on the wafer surface layer is diffused. Defects can be efficiently eliminated. Therefore, a silicon single crystal wafer having very few crystal defects on the wafer surface can be obtained. In addition, since the temperature can be rapidly raised and lowered, crystal defects due to oxygen precipitation and the like do not newly occur during the temperature raising and lowering, and the time required for the heat treatment can be extremely reduced. On the other hand, in the bulk portion of the wafer, the precipitation of oxygen is promoted by the presence of nitrogen, so that a wafer excellent in the so-called intrinsic gettering effect (IG effect) can be manufactured.

In this case, when growing a silicon single crystal rod doped with nitrogen by the Czochralski method, the concentration of nitrogen doped into the single crystal rod is 1 × 10 ¹⁰ -5. It is preferably set to × 10 ¹⁵ atoms / cm ³ . In order to sufficiently suppress the growth of crystal defects, it is desirable that the concentration be 1 × 10 ¹⁰ atoms / cm ³ or more. In order not to hinder the single crystallization of silicon single crystal, This is because it is preferably set to 5 × 10 ¹⁵ atoms / cm ³ or less.

Further, as described in claim 3, when growing a silicon single crystal rod doped with nitrogen by the Czochralski method, the concentration of oxygen contained in the single crystal rod is determined as follows:
It is preferable that the concentration be 1.2 × 10 ¹⁸ atoms / cm ³ (ASTM '79 value) or less. As described above, when the oxygen content is low, the growth of crystal defects can be further suppressed, and the formation of oxygen precipitates on the surface layer can be prevented. On the other hand, in the bulk portion, since oxygen precipitation is promoted by the presence of nitrogen, the IG effect can be sufficiently exhibited even with low oxygen.

Next, in the invention described in claim 4 of the present invention, the heat treatment applied to the wafer by a rapid heating / cooling device is performed at a temperature of 1100 ° C. to a melting point of silicon or lower.
行 な う 60 seconds. By performing a heat treatment at a high temperature such as 1100 ° C. to the melting point of silicon using the rapid heating / cooling apparatus, oxygen and nitrogen in the wafer surface layer can be sufficiently diffused outward, so that crystal defects can be reliably eliminated. And heat treatment time is 6
A very short time such as 0 second or less can be achieved.

In this case, it is preferable that the heat treatment applied to the wafer by the rapid heating / cooling device is performed in an atmosphere of oxygen, hydrogen, argon, or a mixture thereof. By performing the heat treatment in such a gas atmosphere, oxygen and nitrogen can be effectively diffused outward without forming a harmful surface film on the silicon wafer, and crystal defects in the wafer surface layer can be eliminated.

The silicon single crystal wafer (claim 6) manufactured by the manufacturing method of the present invention has extremely low crystal defects. In particular, as described in claim 7, the density of crystal defects in the wafer surface layer is increased. Is not more than 10 / cm ^2, and the COP density in a region from the wafer surface to a depth of 0.2 μm is 8 or less.
Since it can be reduced to × 10 ⁴ / cm ³ or less, the yield at the time of device fabrication can be remarkably improved.

Hereinafter, the present invention will be described in more detail.
The present invention is not limited to these. The present invention
By combining a technique of doping nitrogen during the growth of a silicon single crystal by the CZ method and a technique of applying heat treatment to a silicon single crystal wafer by a rapid heating / cooling device to eliminate crystal defects on the wafer surface, a device forming layer ( The present inventors have found that a silicon single crystal wafer having extremely few crystal defects in a wafer surface layer) can be obtained with high productivity, and the present invention has been completed by carefully examining various conditions.

That is, it has been pointed out that when nitrogen is doped into a silicon single crystal, the aggregation of atomic vacancies in silicon is suppressed and the size of crystal defects is reduced (T. Ab).
e and H. Takeno, Mat.Res.Soc.Symp.Proc.Vol.262,3,199
2). This effect is considered to be due to the transition of the process of aggregation of atomic vacancies from formation of uniform nuclei to formation of heterogeneous nuclei. Therefore, if nitrogen is doped when growing a silicon single crystal by the CZ method, a silicon single crystal with a very small crystal defect size and a silicon single crystal wafer can be obtained by processing the same. Moreover, according to this method, unlike the above-described conventional method, it is not always necessary to reduce the crystal growth rate, and thus it is possible to obtain a silicon single crystal wafer with high productivity.

However, it is known that nitrogen atoms in the silicon single crystal have an effect of promoting oxygen precipitation (for example, see F. Shimura and RSHockett, Appl. Phys.
Lett. 48, 224, 1986), when doped into a silicon single crystal wafer by the CZ method, heat treatment during the device process, etc.
Defects caused by oxygen precipitation, such as OSF (oxidation-induced stacking fault), occur frequently in the device formation layer. Therefore, conventionally, a CZ silicon single crystal wafer doped with nitrogen has not been used as a wafer for device fabrication.

Therefore, the present invention takes advantage of the fact that crystal defects (grown-in defects) are unlikely to grow in a nitrogen-doped crystal. On the other hand, defects generated due to the promotion of oxygen precipitation are limited to wafers. By applying high-temperature heat treatment with a rapid heating / cooling device to diffuse oxygen and nitrogen in the surface layer outward, a silicon single crystal wafer with extremely few crystal defects on the wafer surface was successfully obtained.

Since nitrogen is contained in the bulk portion of the wafer, the precipitation of oxygen is promoted. As a result, the amount of precipitates is larger than that of a normal wafer having no nitrogen and having the same oxygen concentration. Will be strong. Therefore, the concentration of oxygen contained can be reduced, and the generation of crystal defects on the surface can be further suppressed. Moreover,
There is also an advantage that the productivity is high because it is not necessary to lower the crystal pulling speed in the CZ method.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a silicon single crystal rod doped with nitrogen by the CZ method may be grown by a known method described in, for example, Japanese Patent Application Laid-Open No. 60-251190. .

That is, in the CZ method, a seed crystal is brought into contact with a melt of a polycrystalline silicon raw material accommodated in a quartz crucible,
This is a method of growing a silicon single crystal rod of a desired diameter by slowly pulling it up while rotating it. The nitride is put in a quartz crucible in advance, the nitride is put into a silicon melt, or the atmosphere is By setting the gas to an atmosphere containing nitrogen, nitrogen can be doped into the pulled crystal. At this time, by adjusting the amount of nitride, the concentration of nitrogen gas, the introduction time, etc.,
The doping amount in the crystal can be controlled.

As described above, when a single crystal rod is grown by the CZ method, the growth of crystal defects introduced during crystal growth can be suppressed by doping with nitrogen. Also, unlike the conventional method, it is not necessary to reduce the crystal growth rate to, for example, 0.4 mm / min or less in order to suppress the occurrence of crystal defects, so that the productivity of the crystal can be significantly improved. .

When nitrogen is doped into a silicon single crystal,
It is considered that the reason why the growth of crystal defects introduced into silicon is suppressed is that the aggregation process of atomic vacancies shifts from uniform nucleation to heterogeneous nucleation as described above. Therefore, the concentration of nitrogen to be doped is preferably set to 1 × 10 ¹⁰ atoms / cm ³ or more, which causes sufficient heterogeneous nucleation, and more preferably 5 × 10 ¹³ atoms / cm ³ or more. . Thereby, the growth of crystal defects can be sufficiently suppressed. On the other hand, if the nitrogen concentration exceeds the solid solution limit of 5 × 10 ¹⁵ atoms / cm ³ in the silicon single crystal, the single crystallization of the silicon single crystal itself is hindered. .

In the present invention, when growing a silicon single crystal rod doped with nitrogen by the CZ method, the concentration of oxygen contained in the single crystal rod is set to 1.2 × 10 ¹⁸ atoms / cm ³ or less. Is preferred. When the oxygen concentration in the silicon single crystal is set to such low oxygen, the growth of crystal defects can be further suppressed, and the formation of the OSF can be suppressed, in combination with the fact that nitrogen is contained. It is.

When growing the silicon single crystal rod, the concentration of oxygen contained therein may be reduced to the above range by a conventionally used method. For example, the above oxygen concentration range can be easily set by means such as a decrease in the number of rotations of the crucible, an increase in the flow rate of the introduced gas, a decrease in the atmospheric pressure, and a control of the temperature distribution and convection of the silicon melt.

Thus, a silicon single crystal rod doped with nitrogen at a desired concentration in the CZ method and containing oxygen at a desired concentration is obtained. This is sliced by a cutting device such as an inner peripheral blade slicer or a wire saw according to a usual method, and then processed into a silicon single crystal wafer through processes such as chamfering, lapping, etching, and polishing. Needless to say, these steps are merely listed as examples, and there may be various other steps such as washing, and the steps are appropriately changed and used according to the purpose, such as a change in the order of the steps or a partial omission.

Next, the obtained silicon single crystal wafer is subjected to a heat treatment by a rapid heating / rapid cooling device to outwardly diffuse oxygen and nitrogen on the surface of the wafer to eliminate crystal defects. Here, rapid heating and rapid cooling means that a wafer is immediately introduced into a heat treatment furnace set to a desired temperature range,
A method of immediately taking out the wafer after the elapse of a desired heat treatment time, or a method of placing a wafer at a set position in a heat treatment furnace and then immediately performing a heat treatment with a lamp heater or the like. This immediate loading and unloading means that the so-called loading and unloading operations for heating and cooling the wafer in a fixed time and slowly loading and unloading the wafer into the heat treatment furnace, which are conventionally performed, are not performed. is there. However, it takes a certain amount of time to carry the wafer to a predetermined position in the furnace, and it takes several seconds to several minutes depending on the ability of the moving device for loading the wafer.

As a rapid heating / cooling apparatus for a silicon wafer used in the present invention, an apparatus such as a lamp heater using heat radiation can be mentioned. As commercially available products, for example, S
Devices such as the HS-2800 can be mentioned, which are not particularly complex or expensive.

Here, an example of an apparatus for rapidly heating / cooling a silicon wafer used in the present invention will be described. FIG. 3 is a schematic view of a rapid heating / rapid cooling device. The heat treatment apparatus 10 in FIG. 3 has a bell jar 1 made of, for example, silicon carbide or quartz, and heat-treats a wafer in the bell jar 1. Heating is performed by the heaters 2 and 2 ′ arranged so as to surround the bell jar 1. The heater is divided in the vertical direction, so that the power supplied independently can be controlled. Of course, the heating method is not limited to this, and may be a so-called radiant heating or high-frequency heating method. A housing 3 for shielding heat is provided outside the heaters 2 and 2 '.
Is arranged.

A water-cooling chamber 4 and a base plate 5 are arranged below the furnace to block the inside of the bell jar 1 and the atmosphere. The silicon wafer 8 is held on a stage 7, and the stage 7 is attached to the upper end of a support shaft 6 that can move up and down by a motor 9. The water cooling chamber 4 is provided with a wafer insertion port (not shown) that can be opened and closed by a gate valve so that the wafer can be taken in and out of the furnace from a lateral direction.
Further, the base plate 5 is provided with a gas inlet and an outlet, so that the gas atmosphere in the furnace can be adjusted.

The heat treatment for rapidly heating / cooling the silicon wafer by the heat treatment apparatus 10 as described above is performed as follows. First, the inside of the bell jar 1 is heated to, for example, 1100 to a desired temperature equal to or lower than the melting point of silicon in a desired gas atmosphere by the heaters 2 and 2 ′, and is maintained at that temperature. If the supply power is controlled independently for each of the divided heaters, a temperature distribution can be provided in the bell jar 1 along the height direction. Therefore, the processing temperature of the wafer can be determined by the position of the stage 7, that is, the amount of the support shaft 6 inserted into the furnace.

When the inside of the bell jar 1 is maintained at a desired temperature, a silicon wafer is inserted from the insertion port of the water cooling chamber 4 by a wafer handling device (not shown) arranged adjacent to the heat treatment apparatus 10 and is standby at the lowermost position. A wafer is placed on the stage 7 thus moved via, for example, a SiC boat. At this time, since the water cooling chamber 4 and the base plate 5 are water cooled, the temperature of the wafer does not rise at this position.

When the mounting of the wafer on the stage 7 is completed, the support shaft 6 is immediately inserted into the furnace by the motor 9 to move the stage 7 to a desired temperature position of 1100 to the melting point of silicon or less. Then, the silicon wafer on the stage is subjected to a high-temperature heat treatment. In this case, since the movement from the lower end position of the stage in the water cooling chamber 4 to the desired temperature position takes, for example, only about 20 seconds, the silicon wafer is rapidly heated.

Then, by stopping the stage 7 at a desired temperature position for a predetermined time (for example, 1 to 60 seconds),
High-temperature heat treatment for the stop time can be applied to the wafer. When a predetermined time has elapsed and the high-temperature heat treatment is completed, the support shaft 6 is immediately pulled out of the furnace by the motor 9, thereby lowering the stage 7 to the lower end position in the water cooling chamber 4. This lowering operation can be performed, for example, in about 20 seconds. Since the water cooling chamber 4 and the base plate 5 are water-cooled, the wafer on the stage 7 is rapidly cooled. Finally, the heat treatment is completed by taking out the wafer with a wafer handling device. Further, when there is a wafer to be subjected to heat treatment, the temperature of the heat treatment apparatus 10 is not lowered, so that the wafers can be supplied one after another to perform the heat treatment continuously.

As described above, when heat treatment is performed on the wafer of the present invention by the rapid heating / cooling apparatus, the heat treatment to be applied is preferably performed at a temperature of 1100 ° C. to the melting point of silicon for 1 to 60 seconds. By using a rapid heating / cooling device and performing a heat treatment at a high temperature of 1100 ° C. or lower than the melting point of silicon, oxygen and nitrogen in the wafer surface layer can be sufficiently diffused outward, so that crystal defects can be reliably eliminated. This is because the heat treatment time can be made extremely short, such as 60 seconds or less.

In this case, the reason why the heat treatment time is set to 1 to 60 seconds is that the heat treatment needs to be performed for 1 second in order to sufficiently diffuse oxygen and nitrogen outward, and it is sufficient if the heat treatment is performed for 60 seconds. is there. In addition, since the temperature can be raised and lowered rapidly, crystal defects and oxygen precipitation do not newly occur during the temperature raising and lowering.

If the heat treatment is performed in an atmosphere of oxygen, hydrogen, argon, or a mixture of these, oxygen and nitrogen can be effectively removed without forming a harmful surface film on the silicon wafer. In this way, crystal defects in the wafer surface layer can be eliminated. In particular, it is more preferable to perform the high-temperature heat treatment in a reducing atmosphere such as an atmosphere of hydrogen, argon, or a mixture thereof because crystal defects on the wafer surface are easily eliminated.
In addition, it was confirmed that when a mixed atmosphere of hydrogen and argon was used, slip was less likely to occur on the wafer during the heat treatment.

Thus, it is possible to obtain a silicon single crystal wafer by the CZ method doped with nitrogen and having few crystal defects on the surface of the silicon single crystal wafer. In particular, the density of crystal defects in the wafer surface layer can be reliably reduced to 10 / cm ² or less, and can be substantially reduced to zero. Further, the COP density in a region from the wafer surface to a depth of 0.2 μm can be set to 8 × 10 ⁴ / cm ³ or less, and the device fabrication yield can be reliably improved.

[0040]

EXAMPLES The present invention will now be described specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. (Example 1, Comparative Example 1) A quartz crucible having a diameter of 18 inches was charged with 40 kg of raw material polycrystalline silicon by a CZ method, and a crystal rod having a diameter of 6 inches, a P-type and an orientation of <100> was pulled at a normal pulling speed. 0.8 to 1.5 mm /
Ten pieces were pulled up at various speeds in the range of min. Of the five, 0.12g was added to the raw material beforehand.
A silicon wafer having a silicon nitride film was introduced, but nitrogen was not doped in pulling up the remaining five crystals. In addition, the crucible rotation of each crystal was controlled during pulling, and the oxygen concentration in the single crystal was 0.9 to 1.0 × 1.
0 ¹⁸ atoms / cm ³ .

The nitrogen concentration at the tail of the crystal rod doped with nitrogen was measured by FT-IR and found to be 5.0 on average.
× 10 ¹⁴ atoms / cm ³ (Since the segregation coefficient of nitrogen is very small, the concentration of the straight body portion of the crystal rod is lower than this value.) Further, the oxygen concentration of all the single crystal rods was measured by FT-I
As measured by R, all crystals were approximately 0.9-
It was confirmed that the oxygen concentration was 1.0 × 10 ¹⁸ atoms / cm ³ .

A wafer was cut out from the obtained single crystal rod using a wire saw, chamfered, wrapped, etched, and mirror-polished, and the conditions were substantially the same except for the presence or absence of nitrogen doping. A silicon single crystal mirror surface wafer having a diameter of 6 inches was produced.

The obtained silicon single crystal wafer was subjected to Sec.
By performing co-etching and observing the surface with a microscope and measuring the pit density, the density of crystal defects (glow-in defects) from the surface to a depth of 5 μm was measured. The measurement results are shown in FIG. The solid circles indicate the method of the present invention doped with nitrogen, and the open circles indicate the conventional method without nitrogen doping.

The results show that, in the method of the present invention doped with nitrogen, the crystal defect density is higher than that of the conventional method, although the pulling speed is 1.0 mm / min or more, which is equal to or higher than that of the conventional method. Has been reduced to about one-twentieth. In other words, it can be seen that the doping with nitrogen suppresses the growth of crystal defects, and reduces those that are large enough to be detected.

Next, the wafer was heated at 1200 ° C. for 1 hour using a rapid heating / cooling apparatus as shown in FIG.
A 0 second rapid heating / rapid cooling heat treatment was performed. The atmosphere gas was a 100% oxygen gas atmosphere, a 100% argon gas atmosphere, a 100% hydrogen gas atmosphere, or a mixed gas atmosphere of 50% argon and 50% hydrogen.

The wafer after the heat treatment was subjected to Secco etching, the surface was again observed with a microscope, and the pit density was measured to determine whether there was a change in the crystal defect density. The measurement results in the case of doping with nitrogen are plotted in accordance with FIG.

The results show that the crystal defects of the nitrogen-doped wafer surface layer are reduced to about 10 / cm ² or less by the rapid heating / cooling heat treatment at 1200 ° C. That is, it is understood that nitrogen and oxygen diffuse outward by the heat treatment, and the surface of the wafer is made defect-free. In particular, it can be seen that the density of crystal defects in the wafer surface layer can be made substantially zero.

Next, the oxide film breakdown voltage characteristics (C-mode) of the wafer after the heat treatment were measured. Oxide film breakdown voltage characteristics (C
The measurement conditions for (mode) were as follows: oxide film thickness: 25 nm, measurement electrode: phosphorus-doped polysilicon, electrode area: 8 mm ² ,
Judgment current: 1 mA / cm ² . Generally, those having a dielectric breakdown electric field of 8 MV / cm or more are determined to be good. The measurement results are shown in FIG.

When the nitrogen-doped silicon single crystal wafer of the present invention is heat-treated by a rapid heating / cooling device (curves A to D), a good product of 8 MV / cm or more is generated in any heat treatment atmosphere. While the frequency is high and most of the products are good, the conventional method (curve E) has 8MV /
It can be seen that about 70% of defective products of less than cm are generated.

Example 2 and Comparative Example 2 As in Example 1 and Comparative Example 1, the diameter was 8 inches, the p-type, and the azimuth <1 by the CZ method.
Five single crystal rods having a diameter of>00> were pulled up under the conditions shown in Table 1 below, and five types of silicon single crystal mirror surface wafers (a, b, c, d, e) having a diameter of 8 inches were produced.

[0051]

[Table 1]

Regarding the obtained five kinds of wafers, COP (Crystal Originated Particlization) which is a crystal defect considered to be a cluster of atomic vacancies existing on the surface.
The number of e) was measured. In the COP measurement, a thermal oxide film of about 0.44 μm is formed on the wafer surface of the measurement wafer, the oxide film is removed with hydrofluoric acid, and then the wafer is measured using a particle measuring device (KLA / Tencor, SP1). Counting was performed for COPs of 0.10 μm or more present on the surface. By doing so, the distance from the wafer surface is about 0.2 μm.
The COP existing in the region up to the depth can be measured in an integrated form.

Another set of five types of wafers includes:
Rapid heating / rapid cooling device (manufactured by AST, SHS-280)
According to 0), after performing a heat treatment at 1200 ° C. for 10 seconds in a mixed gas atmosphere of 50% argon and 50% hydrogen, similarly, a thermal oxide film of about 0.44 μm is formed, and the oxide film is removed. Was measured for COP. FIG. 4 shows the results of the COP numbers of the respective wafers thus obtained.

As is apparent from FIG. 4, the effect of reducing the COP by the heat treatment by the rapid heating / cooling device is shown in the case of the wafer doped with nitrogen (a, b, and c in FIG. 4). It can be seen that it is larger than (d, e in FIG. 4). Then, the nitrogen-doped wafer is subjected to a heat treatment by a rapid heating / cooling device, whereby the number of COPs from the wafer surface to a depth of 0.2 μm can be reliably reduced to 500 / wafer or less for an 8-inch wafer.
It was found that the density can be reduced to about 8 × 10 ⁴ pieces / cm ³ or less in terms of OP density.

The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the scope of the claims of the present invention. It is included in the technical scope of the invention.

For example, in growing a silicon single crystal rod doped with nitrogen by the Czochralski method in the present invention, it does not matter whether a magnetic field is applied to the melt or not. The Ralski method includes a so-called MCZ method in which a magnetic field is applied.

In the above description, it has been shown that when the oxygen concentration is low, the crystal defects can be further reduced. However, the present invention is not limited to this. It goes without saying that even if the oxygen concentration is as high as 2 to 1.5 × 10 ¹⁸ atoms / cm ³ or higher, the effect is obtained.

[0058]

According to the present invention, the growth of crystal defects in a silicon single crystal produced by the CZ method is suppressed by subjecting a nitrogen-doped silicon single crystal wafer to a heat treatment by a rapid heating / cooling device. Since crystal defects in the surface layer of the wafer can be eliminated, a silicon single crystal wafer having extremely low defects can be easily produced with high productivity.

[Brief description of the drawings]

FIG. 1 is a diagram showing the results of measuring the pit density by observing the surface with a microscope after Secco etching and showing the effect of heat treatment in Example 1 and Comparative Example 1 (black circles indicate the method of the present invention in which nitrogen is doped). Yes, the white circle is the conventional method without nitrogen doping.)

FIG. 2 is a result diagram showing a result of measuring an oxide film breakdown voltage characteristic (C-mode) of a wafer after a heat treatment.

FIG. 3 is a schematic view showing an example of an apparatus capable of rapidly heating and rapidly cooling a silicon wafer.

FIG. 4 is a result diagram of Example 2 and Comparative Example 2.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bell jar, 2, 2 '... Heater, 3 ... Housing, 4 ... Water cooling chamber, 5 ... Base plate, 6
... support shaft, 7 ... stage, 8 ... silicon wafer,
9 ... motor, 10 ... heat treatment device.

Claims (8)

[Claims] 1. A silicon single crystal rod doped with nitrogen is grown by the Czochralski method, the single crystal rod is sliced and processed into a silicon single crystal wafer, and then the silicon single crystal wafer is rapidly heated and cooled. A method for producing a silicon single crystal wafer, wherein heat treatment is performed by an apparatus. 2. When growing a silicon single crystal rod doped with nitrogen by the Czochralski method, the concentration of nitrogen doped into the single crystal rod is 1 × 10 ^{10 to} 5 × 10 ¹⁵ at.
2. The method for producing a silicon single crystal wafer according to claim 1, wherein the production rate is oms / cm ³ . 3. When growing a silicon single crystal rod doped with nitrogen by the Czochralski method, the concentration of oxygen contained in the single crystal rod is set to 1.2 × 10 ¹⁸ atoms / cm ^3.
3. The method for producing a silicon single crystal wafer according to claim 1, wherein: 4. The heat treatment applied to the wafer by a rapid heating / cooling device at a temperature of 1100 ° C. to the melting point of silicon for 1 to 60 seconds. 2. The method for producing a silicon single crystal wafer according to claim 1. 5. The method according to claim 1, wherein the heat treatment applied to the wafer by a rapid heating / cooling device is performed in an atmosphere of oxygen, hydrogen, argon, or a mixture thereof. The method for producing a silicon single crystal wafer according to the above. 6. A silicon single crystal wafer manufactured by the method according to claim 1. 7. The silicon single crystal wafer according to claim 6, wherein the density of crystal defects in the surface layer of the wafer is 10 / cm ² or less. 8. The silicon single crystal wafer according to claim 6,
And a depth of 0.2 μm from the wafer surface.
COP density in the region is 8 × 10⁴Pieces / cm ³Below
A silicon single crystal wafer characterized in that: