JP2000053489A - Production of silicon single crystal wafer for particle monitoring and silicon single crystal wafer for particle monitoring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a silicon single crystal wafer having fewer pits in its surface, with high productivity. SOLUTION: This production comprises growing a silicon single crystal bar doped with nitrogen by a Czochralski method and working the grown single crystal bar into single crystal wafers. Thus, the objective single crystal wafer is produced with 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 method for producing a silicon single crystal wafer for particle monitoring having few pits on a wafer surface with high productivity.

[0002]

2. Description of the Related Art When particles adhere to a silicon single crystal wafer used for a semiconductor device, a pattern may be cut off at the time of manufacturing the semiconductor device. In particular, since the pattern width of the most advanced device (64M DRAM) is as fine as 0.3 μm, even in the case of such a pattern formation, even the presence of particles of 0.1 μm causes abnormalities such as pattern breakage and the like. Yield is significantly reduced. Therefore, particles adhering to the silicon wafer must be reduced as much as possible.

[0003] Therefore, in the silicon wafer manufacturing process, strict control of particles (investigation of generation sources, checking of cleaning effect, level control of clean room, inspection before shipment of final products, etc.) is performed using a particle counter. ing.

A conventional method of measuring a particle counter is, for example, a method in which a monitoring wafer for measuring particles (a wafer for particle monitoring) is 10-1.
A laser spot of about 00 μm is irradiated, and weak scattered light by particles on the wafer surface is effectively collected by a large number of optical fibers and integrating spheres, and is converted into an electric signal by a photoelectric element. Therefore, the conventional particle counter counts the number of points (light spots) where light scattering occurs on the wafer surface.

[0005] By the way, fine crystal defects occur during the growth of silicon single crystal, and do not disappear during cooling of the crystal but remain in the processed wafer as it is. Ammonia water (NH ₄ OH + water) and hydrogen peroxide water (H ₂ O ₂ + water) generally used for removing particles from the wafer
When the substrate is washed in a mixed solution of the above, a crystal defect portion has a high etching rate, so that pits (pits) are formed on the wafer surface (the pits are formed by COP: Crystal Origin).
It is called ated Particle. ).

When such a silicon wafer is used as a wafer for particle monitoring and the number of particles is measured by the particle counter, not only particles actually adhering to the wafer surface but also light scattering due to the pits are detected. There is a drawback that a true number of particles cannot be obtained.

In particular, a wafer manufactured from a silicon single crystal pulled by the CZ method is used in a floating zone melting method (F
It is known that this COP is remarkably larger than a wafer manufactured from a silicon single crystal by the Z method) or an epitaxial wafer in which a silicon single crystal thin film is grown on a wafer by the CZ method.

On the other hand, in the CZ method, in order to reduce crystal defects (COP) introduced during the growth of a silicon single crystal, the crystal growth rate is extremely reduced (for example, 0.4 mm / min).
It is also known that remarkable improvement can be achieved by the following (see, for example, JP-A-2-267195). However, CO
To improve P, simply increase the crystal growth rate to 1 mm / m
If the pressure is reduced to 0.4 mm / min or less from
Although the OP can be improved, the productivity of the single crystal is reduced by half or less, resulting in a significant increase in cost. This is a problem not only for a wafer used for a device but also for a wafer for a particle monitor used when measuring particles.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a silicon single crystal for particle monitoring having few crystal defects by the CZ method is provided.
The purpose is to obtain with high productivity.

[0010]

According to a first aspect of the present invention, there is provided a method of manufacturing a silicon single crystal wafer for particle monitoring, comprising the steps of: adding silicon doped with nitrogen by a Czochralski method; A method for producing a silicon single crystal wafer for particle monitoring, comprising growing a single crystal rod and processing the single crystal rod into a wafer to produce a silicon single crystal wafer for particle monitoring.

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.

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- It is preferably set to 5 × 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, after processing the single crystal rod into a wafer to produce a silicon single crystal wafer, a heat treatment is applied to the silicon single crystal wafer to remove nitrogen on the wafer surface to the outside. Preferably, it is diffused. By subjecting the wafer processed from the nitrogen-doped silicon single crystal to heat treatment to diffuse nitrogen on the wafer surface outward, the wafer surface layer has very few crystal defects and nitrogen is also diffused outward. Therefore, oxygen precipitate defects do not occur on the wafer surface due to promotion of oxygen precipitation by nitrogen. When oxygen is simultaneously diffused outward by this heat treatment, the defect density on the surface can be further reduced. Therefore, it becomes very suitable as a wafer for particle monitoring.

Further, as described in claim 4, 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 (ASTM '79 value)
It is preferable to set the following. 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, so that it is more desirable as a monitoring wafer.

The silicon single crystal wafer for particle monitoring manufactured by the manufacturing method of the present invention (Claim 5) is grown, for example, by doping nitrogen with Czochralski method as in Claim 6. This is a silicon single crystal wafer for particle monitoring obtained by processing a silicon single crystal rod into a wafer.

In this case, the nitrogen concentration is set to 1 × 10 ^{10 to} 5 × 10 ¹⁵ atoms / cm ^3, and the nitrogen on the wafer surface is removed by the heat treatment. In this case, the oxygen concentration can be set to 1.2 × 10 ¹⁸ atoms / cm ³ or less.

With such a silicon single crystal wafer for particle monitoring, the surface layer has very few crystal defects. In particular, since the density of crystal defects on the wafer surface can be reduced to 30 / cm ² or less as described in claim 10, accurate particle measurement can be performed using the density, which is very useful for device process management and the like. Will be useful.

Hereinafter, the present invention will be described in more detail.
The present invention is not limited to these. The present invention
By applying the technique of doping nitrogen during silicon single crystal growth by the CZ method to the production of a wafer for particle monitoring, a silicon single crystal wafer for particle monitoring with few crystal defects in the surface layer of the wafer can be obtained.
They have found that they can be obtained with high productivity, and have scrutinized various conditions to complete the present invention.

That is, it has been pointed out that when nitrogen is doped into a silicon single crystal, aggregation of atomic vacancies in silicon is suppressed (T. Abe and H. Takeno, Mat. Res. So.
c.Symp.Proc.Vol.262,3,1992). This effect is considered to be due to the transition of the process of aggregation of atomic vacancies from the formation of uniform nuclei to the formation of heterogeneous nuclei. Therefore, when a silicon single crystal is grown by the CZ method, by doping with nitrogen, a silicon single crystal having a small crystal defect size can be obtained. You can get a wafer. Moreover, according to this method, unlike the conventional method, it is not always necessary to reduce the crystal growth rate, so that a silicon monitor single crystal wafer for particle monitoring with high productivity and low defect can be obtained.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in the order of steps for manufacturing a silicon single crystal wafer for particle monitoring, but the present invention is not limited to these embodiments. To grow a silicon single crystal rod doped with nitrogen by the CZ method, see, for example,
A known method as described in Japanese Patent Application No. 0-251190 may be used.

That is, in the CZ method, a seed crystal is brought into contact with a melt of a polycrystalline silicon raw material contained 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. Further, unlike the conventional method, in order to suppress the occurrence of crystal defects, it is not necessary to reduce the crystal growth rate to, for example, 0.4 mm / min or less, so that crystal productivity can be significantly improved. .

When nitrogen is doped into a silicon single crystal,
It is considered that the reason why the number of crystal defects introduced into silicon decreases 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. This is because if the oxygen concentration in the silicon single crystal is set to such low oxygen, the growth of crystal defects can be further suppressed in combination with the fact that nitrogen is contained.

When growing a silicon single crystal rod, the concentration of oxygen contained therein can 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 only listed as examples, and there may be various other steps such as washing, and the steps may be appropriately changed and used according to the purpose, such as a change in the order of the steps or a partial omission.

Next, heat treatment may be applied to the obtained silicon single crystal wafer to cause nitrogen on the wafer surface to diffuse outward. It is known that nitrogen atoms in a silicon single crystal have an effect of promoting oxygen precipitation (for example, F. Shimura and RSHockett, Appl. Phys. Lett. 48, 22
4,1986), when doping into a silicon single crystal wafer by the CZ method, defects such as OSF (oxidation-induced stacking fault) due to oxygen precipitation may occur in the surface layer due to heat treatment or the like. The out-diffusion of nitrogen on the wafer surface is because such nitrogen promotes oxygen precipitation, which causes oxygen to precipitate on the wafer surface layer, and the formation of defects based on this causes adverse effects when measuring particles. This is to prevent In combination with the effect of suppressing the growth of crystal defects during the growth of nitrogen crystals, the wafer surface layer can be significantly reduced in defects.

In this case, since the diffusion rate of nitrogen in silicon is much higher than that of oxygen, the heat treatment can surely diffuse nitrogen on the surface outward.
As a specific heat treatment condition for out-diffusing nitrogen on the wafer surface, for example, it is preferable to perform the heat treatment at a temperature of 900 ° C. to the melting point of silicon or lower.

By performing the heat treatment in such a temperature range, nitrogen in the wafer surface layer can be sufficiently diffused outwardly and oxygen can also be diffused out at the same time. It is possible to almost completely prevent the occurrence of defects.

In this way, nitrogen is produced by the Czochralski method.
A silicon single crystal rod grown by doping
The particle monitor of the present invention obtained by processing
A con single crystal wafer can be obtained. Such a pa
Silicon wafer for particle monitor
The layer has very few crystal defects, especially the wafer surface
30 defects / cm ^Two Can be
Since such a wafer can be used as a particle monitor
When used for wafers, the accuracy of particle measurement
It can be significantly improved.

[0031]

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, Comparative Example) 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 formed.
Five wires were lifted at a normal lifting speed of 1.0 mm / min. In the pulling of four of them, the silicon wafer having the silicon nitride film was melted together with the raw material polycrystalline silicon, but the remaining one was not doped with nitrogen. In addition, in all the crystals, the crucible rotation during the pulling was controlled so that the oxygen concentration in the single crystal was 1.3 × 10 ¹⁸
atoms / cm ³ (ASTM '79) or less.

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.) In addition, the oxygen concentration of all single crystal rods
As measured by R, each crystal was approximately 1.3 × 1
It was confirmed that the oxygen concentration was 0 ¹⁸ atoms / cm ³ or less.

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 two kinds of silicon single crystal wafers for particle monitoring obtained in this manner were added with a liquid composition of NH ₄ O.
The particles were washed for 1 hour with an SC-1 cleaning solution in which H: H ₂ O ₂ : H ₂ O = 1: 1: 5, and particles of 0.13 μm or more on the surface were measured by a particle counter. The measurement results are shown in FIG. The solid triangles indicate the method of the present invention doped with nitrogen, and the open circles indicate the conventional method without nitrogen doping.

From these results, it can be seen that in the method of the present invention doped with nitrogen, although the pulling speed is 1.0 mm / min, which is equal to or higher than the conventional speed, the crystal defect density is lower than that of the conventional method. It has been reduced to less than 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. Also,
Regarding the oxygen concentration, it can be seen that if it exceeds 1.2 × 10 ¹⁸ atoms / cm ³ , the crystal defect density may increase slightly.

Next, among the above-mentioned wafers, a nitrogen-doped wafer is subjected to a heat treatment at 1200 ° C. for 30 seconds.
Nitrogen or oxygen on the wafer surface was diffused outward.
The atmosphere gas was a mixed gas atmosphere of 75% argon and 25% hydrogen. Then, after similarly washing with the SC-1 washing solution for 1 hour, particles of 0.13 μm or more on the surface were measured by a particle counter. The measurement result is shown in FIG. 1 as a black circle plot.

According to the results, the crystal defect density is further reduced by out-diffusing nitrogen on the wafer surface, and the crystal defect density is reduced to about 1/40 or less of the conventional method. That is, it can be seen that by doping with nitrogen and outwardly diffusing nitrogen on the wafer surface, generation and formation of crystal defects having a detectable size are extremely suppressed. In particular, the density of crystal defects on the wafer surface can be reliably reduced to 30 / cm ² or less.

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, 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.

[0041]

According to the present invention, a silicon single crystal wafer for particle monitoring having few crystal defects on the wafer surface can be obtained with high productivity. When the particle measurement is performed using the silicon single crystal wafer for particle monitoring of the present invention, the scattering of light due to pits on the wafer surface is extremely small as compared with the conventional wafer for particle monitoring, so that the true number of particles can be accurately calculated. This is very useful for device process management and the like.

[Brief description of the drawings]

FIG. 1 shows a measurement result of a surface crystal defect density measured by a particle counter after cleaning with an SC-1 cleaning solution for 1 hour in Examples and Comparative Examples, with no nitrogen doping, with nitrogen doping and without heat treatment, and with nitrogen doping and heat treatment. It is the figure which compared.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/66 H01L 21/66 Y

Claims (10)

[Claims] In a method for producing a silicon single crystal wafer for particle monitoring, a silicon single crystal rod doped with nitrogen is grown by a Czochralski method, and the single crystal rod is processed into a wafer to produce a silicon single crystal wafer for particle monitoring. A method for producing a silicon single crystal wafer for particle monitoring, comprising producing a crystal wafer. 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 for particle monitoring according to claim 1, wherein the method is set to oms / cm ³ . 3. The method according to claim 1, wherein after processing the single crystal rod into a wafer to produce a silicon single crystal wafer, a heat treatment is applied to the silicon single crystal wafer to diffuse nitrogen on the wafer surface outward. A method for producing a silicon single crystal wafer for particle monitoring according to claim 1 or 2. 4. 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.
The method for producing a silicon single crystal wafer for particle monitoring according to any one of claims 1 to 3, wherein: 5. A silicon single crystal wafer for particle monitoring manufactured by the method according to claim 1. Description: 6. A silicon single crystal wafer for particle monitoring, which is obtained by processing a silicon single crystal rod grown by doping nitrogen with a Czochralski method into a wafer. Silicon single crystal wafer. 7. The nitrogen concentration of the silicon single crystal wafer for particle monitoring is 1 × 10 ^{10 to} 5 × 10 ¹⁵ at.
7. The silicon single crystal wafer for particle monitoring according to claim 6, wherein oms / cm ³ . 8. The silicon single crystal for particle monitoring according to claim 6, wherein nitrogen on the surface of the silicon single crystal wafer for particle monitoring is outwardly diffused by heat treatment. Weeha. 9. An oxygen concentration of the silicon single crystal wafer for particle monitoring is 1.2 × 10 ¹⁸ atoms / cm ^3.
The silicon single crystal wafer for particle monitoring according to any one of claims 6 to 8, wherein: 10. The method according to claim 6, wherein:
2. The silicon single crystal wafer for particle monitoring according to item 1, wherein the density of crystal defects on the wafer surface is 30 / cm ² or less.