JPH11335198A - Silicon single crystal wafer and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a wafer having few grown-in defects such as a COP(crystal originated particle) by regulating the in-plane distribution of the COP, an oxygen concentration and/or an impurity concentration observed in the silicon single crystal wafer so as to be one or more kinds of concentric circular, helical and radial shapes. SOLUTION: When a wafer obtained from a grown silicon single crystal has a in-plane distribution of a COP, an oxygen concentration and/or an impurity concentration regulated so as to have concentric circular, helical or radial shapes having >=1 mm distances thereof, an area density of the COP regulated so as to be <=1.6/cm<2> or a defect-free region regulated so as to be >=20% based on the whole area of the wafer, grown-in defects are decreased and the yield of devices is improved. The wafer is obtained by applying a cusped magnetic field on a molten liquid to stabilize the condition of the molten liquid at the interface while growing the single crystal, changing the growth rate of a micro single crystal and a molten liquid temperature in good accuracy, changing the oxygen concentration and the impurity concentration, and forming an absorbing layer of point defects in good control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon single crystal wafer produced by the Czochralski method (hereinafter referred to as Cz method) having few crystal defects, and a method for producing the same. In particular, COP (Crystal Originated)
Particle) low silicon single crystal wafer,
And its manufacturing method.

[0002]

2. Description of the Related Art In a silicon single crystal pulled by a conventional Cz method, crystal defects are formed in the crystal during single crystal pulling. A crystal defect formed during single crystal pulling is called a “Grown-in defect”.
The in defect is given various names depending on the detection method. For example, a pit that has a special ripple pattern (flow pattern) that appears on the wafer surface by immersing a silicon wafer in a Seco liquid that is a selective etching liquid is called a flow pattern defect. An infrared laser that is incident on a silicon wafer and detected by its scattering is called an infrared scattering defect. Further, after cleaning in a mixed solution of ammonia water and hydrogen peroxide solution generally performed for removing particles in a silicon wafer manufacturing process, the wafer surface is about 0.05 to 0.20 μm (about 0.15 μm).
What is detected by the particle inspection apparatus as a pit having a size of m) is called a COP. Since the COP was first discovered by a particle inspection apparatus, it is named as “particle” originating from a crystal. However, a subsequent investigation has revealed that the defect is not a particle but a pit. .

When a silicon wafer having a COP is used for a semiconductor device and a gate oxide film having a MOS structure, which is a basic element structure of the semiconductor device, is formed on a position where the COP is present, the reliability of the device is remarkably increased. If the wiring is formed, the pattern may be cut. In particular, recently the mainstay device (64M-DRA)
Since the element structure of M) is very fine, 0.3 μm, the pit of about 0.15 μm causes a serious defect, and significantly reduces the production yield of the device. Therefore,
It is desirable to reduce the COP of the silicon wafer as much as possible.

[0004] Recent studies have shown that flow pattern defects,
It has been revealed that the origins of the infrared scattering defect and the origin of the grown-in defect such as COP are the same, and the substance is an octahedral void (cavity). The voids are formed when the atomic vacancies (a kind of point defect) taken in immediately after the single crystal is solidified become supersaturated as the single crystal is cooled, and eventually pass through a temperature range around 1100 ° C. to 1050 ° C. It has become clear that they are formed by agglomeration.

[0005] Based on the above findings, the Green-in
As a method of reducing defects, many proposals have been made on improvement of cooling conditions of a single crystal after solidification. For example,
Japanese Patent Application Laid-Open No. 3-275598 discloses a method in which the cooling rate from the solidification of a crystal to 900 ° C. is set higher than 1.2 ° C./min in order to reduce the COP. According to the publication, in order to reduce COP, the cooling rate from 1200 ° C. to 800 ° C. is set to 0.4 ° C.
/ Min is disclosed in Japanese Patent Application Laid-Open No. HEI 6-1687.
Japanese Patent Application Laid-Open No. 6-279188 discloses a method in which a temperature gradient in a range from immediately above a solid-liquid interface of a silicon melt to 3 cm is set to 5 ° C./cm or more in order to improve the reliability of a gate oxide film. In order to reduce COP or flow pattern defects or infrared scattering defects,
A method of holding a silicon single crystal at a temperature between 1420 ° C. and 1200 ° C. for one hour or more is disclosed in Japanese Patent Application Laid-Open No. H08-1249.
In Japanese Patent Publication No. 3 (2003), in order to reduce infrared scattering defects or improve the reliability of a gate oxide film, the temperature gradient in the crystal axis direction in a temperature range from a silicon melt to 1300 ° C. is G (° C./mm). And the pulling speed of the single crystal is f
_{When p} (mm / min), f _p / G is 0.25 mm ² /
A method is described in which the cooling rate from 1150 ° C. to 1000 ° C. is 2.0 ° C./min or less.

[0006] However, all of these methods change the cooling conditions of the single crystal to obtain the grown-i.
This is a method for reducing n defects, and in order to provide the same effect uniformly over the entire length of the single crystal, it is necessary to change the structure of the pulling furnace and the structure inside the pulling furnace, leading to an increase in cost. Also, in these methods, the Green-i
Although it is possible to apparently reduce the size of the void defect, which is the origin of the n-defect, or to apparently decrease the density, it is not possible to reduce the concentration itself of the atomic vacancy, which is a component (raw material) of the void defect. could not. Therefore, there has been a demand for a method of reducing the concentration of atomic vacancies during the growth of a single crystal, but there has been no such method.

In a general Cz method, polycrystalline silicon is put in a quartz crucible and melted, and a silicon single crystal is seeded in the melt and then pulled up. Since the melt is always in contact with the quartz crucible, it contains a large amount of oxygen atoms dissolved from the quartz crucible, and the silicon single crystal pulled from the melt also contains a large amount of supersaturated solid solution oxygen atoms. ing.

On the other hand, in addition to the method of manufacturing a silicon single crystal by the general Cz method, the C
A method of pulling a single crystal by the z method (MCZ method, Mag
net-field applied Cz method).

In the MCZ method, depending on the method of applying a magnetic field,
There are a cusp magnetic field applying MCZ method and a horizontal magnetic field applying MCZ method. The MCZ method has been proposed as a technique for controlling the oxygen concentration by controlling the flow of a melt by a magnetic field.

A single crystal pulling apparatus using a cusp magnetic field applying MCZ method is disclosed in, for example, Japanese Patent Application Laid-Open No. 58-217493, in which a same-polar opposing magnet (for example, a superconducting magnet) is provided above and below the outer wall of the pulling apparatus. A furnace provided between the two poles of the magnetic field applying device, a quartz crucible provided inside the furnace and holding a silicon melt, a heater for heating the silicon melt, and a silicon single crystal rod pulled up while rotating. And a lifting mechanism. An equiaxially symmetric and radial cusp magnetic field is formed in the melt by the same-pole opposed magnet. By applying a cusp magnetic field, the heat convection of the silicon melt in the quartz crucible is uniformly suppressed, and an axially symmetric temperature distribution is obtained, so that a single crystal having uniform crystallinity can be pulled. Further, since the convection of the melt in the radial direction can be suppressed, the mixing of oxygen from the quartz crucible can be reduced. However, although the conventional cusp magnetic field applying MCZ method is used for reducing the oxygen concentration, it has not been applied to the reduction of a grown-in defect such as COP.

A single crystal pulling apparatus using a horizontal magnetic field applying MCZ method is disclosed in, for example, JP-A-56-45889. Furnace body provided between, and a quartz crucible provided inside the furnace body and holding a silicon melt,
It has a heater for heating the silicon melt and a pulling-up mechanism for pulling up the silicon single crystal rod while rotating it. By suppressing the thermal convection of the silicon melt in the quartz crucible by applying a horizontal magnetic field, the mixing of oxygen from the quartz crucible is greatly reduced and the solid-liquid interface of silicon is kept more static. be able to. However, the conventional horizontal magnetic field applying MCZ method may be used to reduce oxygen concentration,
It was not applied to the reduction of wn-in defects.

In addition, the in-plane distribution of COP of a conventional silicon single crystal wafer in which the grown-in defect is reduced by improving the cooling method or the like has a disk-like shape existing inside a circle having the same center as the wafer. However, it was not distributed only on a concentric line, or had a spiral, radial, or a combination thereof. When a wafer in which COP is distributed on such a line is used for a semiconductor device, COP
The number of devices affected by the COP is smaller than that of a conventional wafer in which the particles are distributed in a disk shape, and the device yield is improved. Accordingly, there has been a demand for a wafer in which the COP is distributed on the line as described above, but there has been no conventional wafer.

[0013]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has few crystal defects.
An object of the present invention is to provide a silicon single crystal wafer having few row-in defects and a method for manufacturing the same.

[0014]

The object of the present invention is achieved by the following means.

(1) A silicon single crystal wafer obtained from a silicon single crystal grown by the Czochralski method, wherein the in-plane distribution of COP, oxygen concentration and / or impurity concentration found in the wafer is concentric. A single crystal silicon wafer characterized in that the silicon single crystal wafer is in one or more of a shape of spiral, spiral and radial.

(2) The silicon single crystal wafer according to (1), wherein the spacing is 1 mm or more in the form of in-plane distribution of the wafer.

(3) In the silicon single crystal wafer, the area density of COP having a diameter of 0.10 μm or more in terms of diameter is 1.6 / cm ² or less on average over the entire area of the wafer (1) or (1). The silicon single crystal wafer according to 2).

(4) In the silicon single crystal wafer, the area of the region where the COP does not exist is 20% or more of the entire area of the wafer.
The silicon single crystal wafer according to any one of (3).

(5) A method of manufacturing a silicon single crystal wafer by the Czochralski method, wherein an absorption layer of point defects is formed in the silicon single crystal during growth of the silicon single crystal. Production method.

(6) When the fluctuation of the single crystal growth rate at the solid-liquid interface during the growth of the silicon single crystal or the fluctuation of the oxygen concentration and / or the impurity concentration due to the fluctuation of the melt temperature at the solid-liquid interface is less than 5%. The method for producing a silicon single crystal wafer according to (5), wherein the silicon single crystal is grown in a certain hot zone.

(7) The fluctuation of the single crystal growth rate at the solid-liquid interface during the growth of the silicon single crystal, or the fluctuation of the oxygen concentration and / or the impurity concentration due to the fluctuation of the melt temperature at the solid-liquid interface are continuously detected. Or periodically, up to 5
(5) or (6), wherein the absorption layer for the point defect is formed in the single crystal.

(8) The silicon single crystal wafer according to (7), wherein the variation applied continuously or periodically with the growth of the silicon single crystal is 0.5 mm or more in the pulling direction of the single crystal. Production method.

(9) The method for manufacturing a silicon single crystal wafer according to (7), wherein the variation is to change the rotation speed of the single crystal or the crucible continuously or periodically.

(10) When the diameter of the silicon single crystal is D (in), the rotation speed of the single crystal is from 2000 / D ² to 600 / D ² (rpm) to 300 / D.
^The transition time is reduced to 2 to 0 (rpm) in 2 minutes to 1 second, and the rotation speed of the single crystal is subsequently reduced to 300 / D ^{2 to} 0 (rpm).
The method according to (9), wherein after the single crystal is grown for 1 second to 1 minute, the rotation speed of the single crystal is increased from 2000 / D ² to 600 / D ² (rpm) in a transition time of 2 minutes to 1 second. A method for manufacturing a silicon single crystal wafer.

(11) The pulling speed of the silicon single crystal is varied continuously or periodically (7) to (1).
0) The method for producing a silicon single crystal wafer according to any one of the above 1).

(12) The method for producing a silicon single crystal wafer according to any one of (5) to (11), wherein a magnetic field is applied to the melt during the growth of the silicon single crystal.

(13) The method for manufacturing a silicon single crystal wafer according to (12), wherein the application of the magnetic field is an application of a cusp magnetic field of 100 gauss or more on the wall of the quartz crucible containing the melt.

(14) The method for manufacturing a silicon single crystal wafer according to (13), wherein the magnetic field strength of the cusp magnetic field or the zero magnetic field position is continuously or periodically varied.

(15) The method for manufacturing a silicon single crystal wafer according to (12), wherein the application of the magnetic field is an application of a horizontal magnetic field of 500 gauss or more on the wall of the quartz crucible containing the melt.

(16) The method for producing a silicon single crystal wafer according to (15), wherein the magnetic field strength of the horizontal magnetic field is continuously or periodically varied.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS When a silicon single crystal is grown by the Cz method, point defects (atomic vacancies and interstitial atoms) are incorporated into the single crystal from the solid-liquid interface. The vacancies and interstitial atoms annihilate and decrease as the single crystal cools, but the concentration incorporated in the single crystal is several orders of magnitude higher in the vacancies, so that The remaining point defects become vacancies. These atomic vacancies become supersaturated as the single crystal is cooled, and when the single crystal is cooled to 1100 ° C. or lower, it is more stable to aggregate than to exist alone and to form an aggregate. A void defect, which is the origin of a grown-in defect such as COP, is formed by aggregation of supersaturated vacancies at 1100 ° C. or lower.

The present inventors have thought that it is necessary to reduce the concentration of atomic vacancies, which are constituents of void defects, in order to drastically reduce the void defects in a silicon single crystal wafer, and have earnestly considered. investigated. As a result, they have found that it is important to have a specific form of defect distribution in order to reduce the concentration of atomic vacancies in the wafer.
That is, a wafer obtained from a silicon single crystal grown by the Cz method, wherein COP,
When a semiconductor device is manufactured using a silicon single crystal wafer in which the in-plane distribution of the oxygen concentration and / or the impurity concentration is one or more of concentric, spiral, and radial forms, a GOP such as COP is used. Since the region where the -in defect exists becomes linear (strip-like), the number of devices affected by defects such as COP is reduced, and the device yield is improved.

In the case of the in-plane distribution of the COP, the oxygen concentration and / or the impurity concentration, when the interval is 1 mm or more, a region where no grown-in defect exists can be widely secured in the wafer, and Can be further reduced, and the device yield is further improved.

The area density of such COPs is
1.6 wafers / cm on average for the entire wafer ^TwoIf
The yield of semiconductor devices manufactured using the wafer is
It becomes even better.

When the area of the defect-free region where no COP exists is 20% or more of the area of the entire wafer, the device yield is further improved. Where CO
The P existence area is an area within a radius of 4 mm around the COP position. Therefore, the region where the COP does not exist refers to a region obtained by subtracting the region where the COP exists from the entire surface of the wafer.

The size and number of COPs can be measured by a foreign substance inspection device utilizing laser scattering, and can be measured by an atomic force microscope (AFM, Atomic Force M).
(microscopic).

The manufacturing method is not particularly limited as long as it is a silicon single crystal wafer having such a quality, but in order to manufacture efficiently, an absorption layer of point defects is formed in the single crystal during single crystal growth. Was found to be effective, whereby a defect-free layer was formed widely around the point defect absorbing layer. Here, the point defect absorption layer indicates a region having a high density in the density distribution of the point defect density. That is, a region where the concentration is increased due to gettering of the surrounding point defects, a region adjacent to the region where the point defects are reduced by the reaction, or a region where the concentration of the point defects formed when the single crystal is solidified is high. Are also included in the point defect absorption layer.

Further, the present inventors have found that the fluctuation of the growth rate of the micro single crystal at the solid-liquid interface during the growth of the silicon single crystal and the fluctuation of the oxygen concentration and impurity concentration due to the fluctuation of the melt temperature at the solid-liquid interface. It has been found that when growing a silicon single crystal with an assembly structure (hot zone structure) inside the pulling furnace of less than 5%, an absorption layer for point defects can be formed with very good control.

In order to more positively form the point defect absorption layer, the growth rate of the micro single crystal at the solid-liquid interface during growth of the silicon single crystal is changed, or the melting rate at the solid-liquid interface is increased. Oxygen concentration
By varying the impurity concentration, it has been found that an absorption layer of point defects can be formed at a certain interval in the crystal axis direction and perpendicular to the crystal axis. Here, the impurity is
Metal elements such as carbon and aluminum, copper and tin, including dopants such as boron and phosphorus.

By giving this variation continuously or periodically, absorption layers of point defects can be formed at regular intervals in the longitudinal direction of the single crystal.
It was found to be effective for reducing wn-in defects. Here, the term “periodic” refers to a step-like or pulse-like (ie, digital) change when changing from a certain value to another value. The term “continuous” refers to a gradual (analog) variation. further,
It has been found that the larger the variation, the greater the effect. However, if the variation exceeds 5%, large crystal deformation is likely to occur, making it difficult to produce a single crystal.

When the interval at which the continuous or periodic fluctuation is provided is less than 0.5 mm in the pulling direction of the single crystal, the pulled single crystal is sliced, and the silicon single crystal having a thickness of 0.5 mm or more is sliced. When manufacturing a crystal wafer, it is difficult to separate a point defect absorbing layer from a defect-free layer.

Further, by changing the rotation speed of the single crystal or the crucible during the growth of the single crystal, the growth rate of the micro single crystal at the solid-liquid interface can be changed relatively easily, or the growth rate at the solid-liquid interface can be changed. This is effective because the oxygen concentration and the impurity concentration can be changed by changing the melt temperature. The absorbing layer formed by this method has a concentric, spiral, or radial form, or a combination of these forms.

In particular, the diameter of the silicon single crystal is set to D (in)
, The rotation speed of the single crystal is 2000 / D ² -60
The transition time is reduced from 0 / D ² (rpm) to 300 / D ² ０0 (rpm) in 2 minutes to 1 second, and the rotation speed of the single crystal is subsequently reduced from 1 second to 1 at 300 / D ² ０0 (rpm). After growing the single crystal for one minute, the rotation speed of the single crystal is set to 2000 / D ^2-
When the transition time is increased to 600 / D ² (rpm) in a transition time of 2 minutes to 1 second, it is preferable because an absorption layer of point defects can be formed in the single crystal with good controllability.

Further, the pulling speed of the silicon single crystal can be changed continuously or periodically, the growth speed of the micro single crystal at the solid-liquid interface can be easily changed, or the temperature of the melt at the solid-liquid interface can be easily changed. Is preferable because the oxygen concentration and the impurity concentration can be changed by the fluctuation of the point defect, so that the point defect absorption layer can be effectively formed together with other fluctuations.

In order to more accurately control the formation of the point defect absorbing layer in the single crystal, it is important that the present inventors control the generation of crystal defects when no fluctuation is applied. I came to the idea. Therefore, during the growth of the silicon single crystal, the above operation was performed in a state where a magnetic field was applied to the melt. As a result, the state of the melt when no fluctuation was applied was more stabilized, and the controllability was extremely high. It has been found that a point defect absorbing layer can be formed well.

When the application of the magnetic field is the application of a cusp magnetic field of 100 Gauss or more on the crucible wall accommodating the melt, the heat convection of the melt is uniformly suppressed, and the axially symmetric temperature distribution is reduced. Therefore, there is a remarkable effect on stabilization of the melt. Note that if the applied magnetic field strength is less than 100 Gauss, the effect of applying the cusp magnetic field is not seen, so it is desirable to apply a magnetic field strength of 100 Gauss or more.

In the case of the cusp magnetic field, since the same-pole opposed magnet is used, there is a position where the magnetic field intensity becomes zero on the center axis of the cusp magnetic field (zero magnetic field position). The height of the zero magnetic field position can be easily changed by mechanically raising and lowering the entire same-pole counter magnet or electrically changing the generated magnetic field strength of each counter magnet. By changing the magnetic field strength or zero magnetic field position continuously or periodically with the cusp magnetic field applied, the state of the melt at the interface can be controlled while being stable. It is possible to accurately change the growth rate of a single crystal or to change the oxygen concentration and the impurity concentration by changing the melt temperature at the solid-liquid interface. Therefore, the controllability of the formation of the point defect absorbing layer is excellent. In addition, by changing the pulling speed continuously or periodically with the cusp magnetic field applied, the state of the melt at the interface can be controlled while being stable, so that the micro-scale at the solid-liquid interface can be controlled. It is possible to accurately change the growth rate of the single crystal or change the oxygen concentration and the impurity concentration by changing the melt temperature at the solid-liquid interface. Therefore, the controllability of the formation of the point defect absorbing layer is excellent.

When the application of the magnetic field is the application of a horizontal magnetic field of 500 gauss or more on the wall of the quartz crucible accommodating the melt, by suppressing the heat convection of the melt in the crucible, the solid-liquid interface is suppressed. Has a remarkable effect on stabilization of the melt. When the applied magnetic field strength is less than 500 gauss, the effect of applying the horizontal magnetic field is not seen, so it is desirable to apply a magnetic field strength of 500 gauss or more.

By changing the magnetic field strength continuously or periodically with the horizontal magnetic field applied, the state of the melt at the interface can be controlled while being stable.
Excellent controllability of formation of the point defect absorption layer.

The dislocation-free silicon single crystal manufacturing apparatus used in the present invention is not particularly limited as long as it is used for manufacturing a dislocation-free silicon single crystal by the usual Cz method. The device was used.

This Cz method silicon single crystal manufacturing apparatus comprises a crucible 6 composed of a quartz crucible 6a for accommodating a silicon melt M and a graphite crucible 6b for protecting the same, and a dislocation-free silicon single crystal ingot S This is a crystal pulling furnace 1 that accommodates. The side surfaces of the crucible 6 are arranged so as to surround the heater 4 and the heat insulating material 3 in order to prevent heat from the heater 4 from escaping to the outside of the crystal pulling furnace. The crucible 6 is connected to the apparatus by a rotating jig 5 and is rotated at a predetermined speed by the driving device. The crucible 6 is moved up and down to compensate for a decrease in the liquid level due to a decrease in the silicon melt in the crucible 6. I have. A hanging pulling wire 7 is provided in the pulling furnace 1, and a chuck 9 for holding a seed crystal 8 is provided at a lower end of the wire. The upper end side of the pulling wire 7 is provided with a pulling device that is wound up by the wire hoist 2 and pulls up a dislocation-free silicon single crystal ingot. Then, Ar gas is introduced into the pulling furnace 1 from a gas inlet 10 formed in the pulling furnace 1, flows through the pulling furnace 1, and is discharged from a gas outlet 11. The reason why the Ar gas is circulated in this way is to prevent SiO generated in the pulling furnace 1 as silicon is melted from being mixed into the silicon melt.

As the cusp magnetic field applying silicon single crystal manufacturing apparatus used in the present invention, as shown in FIG. 2, a general manufacturing apparatus in which the same-pole opposed magnets 20 are arranged vertically on the crystal axis was used.

Further, as shown in FIG. 3, the horizontal magnetic field applying silicon single crystal manufacturing apparatus used in the present invention is a general manufacturing apparatus in which a pair of electromagnets 30 capable of generating a magnetic field in the horizontal direction are arranged on the left and right. Was used.

The yield of the semiconductor device manufactured using the silicon single crystal wafer of the present invention can be known from the pass rate of the reliability test of the gate oxide film in the MOS structure which is the basic structure of the device. Gate oxide reliability is CO
Since it is extremely sensitive to P, the rate of occurrence of semiconductor device defects caused by COP can be known from the pass rate of the reliability test of the gate oxide film. The specific method of the reliability test of the gate oxide film of the silicon single crystal wafer of the present invention is as follows. Forming a MOS diode on a mirror-finished silicon wafer sample and examining the electrical characteristics of a gate oxide film (insulating oxide film), which is a 25.0 nm silicon dioxide film formed in a dry oxygen atmosphere at 1000 ° C. Made by. The MOS diode has a two-layer structure of polycrystalline silicon and aluminum doped with phosphorus at 1 × 10 ²¹ atoms / cm ³ or more on a gate oxide film, has an electrode having an area of 20 mm ² , and has a back surface formed of gold for an ohmic electrode. Electrodes are formed. MOS with the above structure
Diodes were fabricated on the entire surface of the sample wafer. A DC voltage having a polarity into which majority carriers are injected from the substrate silicon was applied to each MOS diode, and the withstand voltage characteristics of the gate oxide film of the sample wafer were evaluated by a voltage lapping method. The average electric field (dielectric breakdown field) applied to the gate oxide film when the current density flowing through the gate oxide film was 1 mA / cm ² was measured. At this time, the breakdown electric field is 8.0 MV.
Various studies have revealed that when it is less than / cm, the withstand voltage characteristics of the gate oxide film are reduced due to crystal defects such as COP. That is, a MOS diode having a breakdown field of 8.0 MV / cm or more is a diode that has passed the gate oxide film test.

In the case of a general wafer processed from a silicon single crystal manufactured by the conventional method, the ratio of the number of MOS diodes having a breakdown electric field of 8.0 MV / cm or more to the total number (that is, the gate oxide film) Exam pass rate)
Is at most less than 30%. Therefore, when the pass rate of the gate oxide film test is 60% or more, the reliability of the gate oxide film is excellent. That is, it is excellent as a semiconductor device wafer.

[0056]

EXAMPLES The present invention will be described below with reference to examples, but it goes without saying that the present invention is not limited by the description of these examples.

The use of the "stable hot zone" as used herein means that the growth rate of the micro single crystal at the solid-liquid interface during the growth of the silicon single crystal or the melt temperature fluctuation at the solid-liquid interface. This means that a silicon single crystal is grown by using an assembly structure (hot zone structure) inside the pulling furnace in which the variation in oxygen concentration and impurity concentration is less than 5%. Further, as shown in FIG. 4, the “fluctuation interval” means an interval in which a silicon single crystal is varied continuously or periodically in accordance with the growth thereof, and this interval is a crystal growth length in units of time. It may be a unit. As shown in FIG. 5, the fluctuation distribution in the wafer resulting from this fluctuation is caused by continuous or periodic fluctuation artificially given together with macro base fluctuation and micro base fluctuation caused by the hot zone. A distribution in which micro-artificial fluctuations are superimposed.

The “COP area density” refers to a COP of 0.10 μm or more in terms of diameter over the entire area of the wafer.
The average density of P. The “COP non-existing area ratio” means the ratio of the area obtained by subtracting the COP existing area from the entire area of the wafer to the entire surface of the wafer. Note that CO
The P existence area is an area within a radius of 4 mm around the COP position.

Example 1 Using the apparatus shown in FIG. 1, a P-type (boron-doped) silicon single crystal ingot having a diameter of 8 inches was grown under the following conditions.

Absorption layer of point defect: Yes Stable hot zone: No Rotation speed of single crystal: Decrease from 18 rpm to 1 rpm in 2 seconds, hold at 1 rpm for 5 seconds, and then increase from 1 rpm to 18 rpm in 2 seconds Rotation speed of crucible: constant at 8 rpm Average pulling speed: 1.0 mm / min Artificial fluctuation of growth rate at solid-liquid interface: yes Artificial fluctuation of melt temperature at solid-liquid interface: yes Interval: 0.3 mm A wafer was cut out from the ingot grown under these conditions, and the results of measurement of the oxygen concentration, impurity (boron) concentration and distribution of COP, and the reliability test of the gate oxide film were performed. .

Example 2 Using the apparatus of FIG. 1, a P-type (boron-doped) silicon single crystal ingot having a diameter of 8 inches was grown under the following conditions.

Absorption layer of point defect: Yes Stable hot zone: Yes Single crystal rotation speed: constant at 20 rpm Crucible rotation speed: constant at 8 rpm Pulling speed: reduced from 1.0 mm / min to 0.2 mm / min in 3 seconds After holding at 0.2 mm / min for 10 seconds, the operation of increasing from 0.2 mm / min to 1.0 mm / min for 2 seconds is periodically performed. Artificial fluctuation of the growth rate at the solid-liquid interface: Yes Solid-liquid Artificial fluctuation of melt temperature at interface: Yes Fluctuation interval: 0.4 mm A wafer was cut out from an ingot grown under this condition, and the oxygen concentration, impurity (boron) concentration and COP distribution were measured, and the gate oxide film was measured. Tables 1 to 3 show the results of the reliability test.

Example 3 Using the apparatus shown in FIG. 1, a P-type (boron-doped) silicon single crystal ingot having a diameter of 8 inches was grown under the following conditions.

Absorption layer for point defects: Yes Stable hot zone: No Rotation speed of single crystal: Constant 19 rpm Rotation speed of crucible: Decrease from 10 rpm to 1 rpm in 3 seconds, hold at 1 rpm for 10 seconds, then 1 rpm to 10 rpm The operation of raising the temperature in 3 seconds is continuously performed Average pulling speed: 0.6 mm / min Artificial fluctuation of the growth rate at the solid-liquid interface: Yes Artificial fluctuation of the melt temperature at the solid-liquid interface: Yes Interval: 0.5 mm A wafer was cut out from an ingot grown under these conditions, and the results of measurement of the oxygen concentration, impurity (boron) concentration, distribution of COP, and reliability test of the gate oxide film are shown in Tables 1 to 3. .

Example 4 Using the apparatus shown in FIG. 1, a P-type (boron-doped) silicon single crystal ingot having a diameter of 8 inches was grown under the following conditions.

Absorption layer for point defects: Yes Stable hot zone: Yes Single crystal rotation speed: Decrease from 18 rpm to 1 rpm in 130 seconds, hold at 1 rpm for 20 seconds, then 1 rpm
Periodical operation of increasing from m to 18 rpm in 130 seconds Rotation speed of crucible: constant at 8 rpm Average pulling rate: 0.2 mm / min Artificial fluctuation of growth rate at solid-liquid interface: yes Melting at solid-liquid interface Artificial fluctuation of liquid temperature: Yes Interval of fluctuation: 1.5 mm A wafer was cut out from an ingot grown under these conditions, and the oxygen concentration, impurity (boron) concentration, COP distribution state measurement, and gate oxide film reliability test were performed. The results obtained are shown in Tables 1 to 3.

Example 5 Using the apparatus of FIG. 1, a P-type (boron-doped) silicon single crystal ingot having a diameter of 8 inches was grown under the following conditions.

Absorption layer of point defect: Yes Stable hot zone: Yes Single crystal rotation speed: 18 rpm constant Crucible rotation speed: Decrease from 8 rpm to 1 rpm in 2 seconds, hold at 1 rpm for 20 seconds, then 1 rpm to 1 rpm
The operation of raising to 0 rpm in 2 seconds is continuously performed. Average pulling speed: 1.0 mm / min. Artificial fluctuation of growth rate at solid-liquid interface: yes. Artificial fluctuation of melt temperature at solid-liquid interface: yes. Interval: 2.0 mm A wafer was cut out from the ingot grown under these conditions, and the results of measurement of the oxygen concentration, impurity (boron) concentration and distribution of COP, and the reliability test of the gate oxide film were performed. Show.

Example 6 Using the apparatus of FIG. 1, a P-type (boron-doped) silicon single crystal ingot having a diameter of 8 inches was grown under the following conditions.

Absorption layer of point defect: Yes Stable hot zone: No Rotation speed of single crystal: Decrease from 18 rpm to 1 rpm in 3 seconds, hold at 1 rpm for 20 seconds, then increase from 1 rpm to 18 rpm in 3 seconds Rotation speed of crucible: constant at 9 rpm Average pulling speed: 1.2 mm / min Artificial fluctuation of growth rate at solid-liquid interface: yes Artificial fluctuation of melt temperature at solid-liquid interface: yes Interval: 3.5 mm A wafer was cut out from the ingot grown under these conditions, and the results of measurement of the distribution of oxygen concentration, impurity (boron) concentration and COP, and the reliability test of the gate oxide film are shown in Tables 1 to 3. .

Example 7 Using the apparatus shown in FIG. 1, a P-type (boron-doped) silicon single crystal ingot having a diameter of 8 inches was grown under the following conditions.

Absorption layer for point defects: Yes Stable hot zone: Yes Rotation speed of single crystal: constant at 18 rpm Rotation speed of crucible: constant at 12 rpm Pulling speed: reduced from 1.0 mm / min to 0.0 mm / min in 5 seconds After holding at 0.0 mm / min for 30 seconds, periodically perform an operation of increasing from 0.0 mm / min to 1.0 mm / min in 5 seconds Artificial fluctuation of the growth rate at the solid-liquid interface: Yes Solid-liquid Artificial fluctuation of melt temperature at interface: Yes Fluctuation interval: 4.0 mm A wafer was cut out from an ingot grown under these conditions, and the oxygen concentration, impurity (boron) concentration and COP distribution were measured, and the gate oxide film was measured. Tables 1 to 3 show the results of the reliability test.

Example 8 Using the apparatus shown in FIG. 2, a P-type (boron-doped) silicon single crystal ingot having a diameter of 8 inches was grown under the following conditions.

Absorption layer for point defects: Yes Stable hot zone: Yes Rotation speed of single crystal: Decrease from 18 rpm to 1 rpm in 2 seconds, hold at 1 rpm for 20 seconds, then increase from 1 rpm to 18 rpm in 2 seconds Rotation speed of crucible: constant at 8 rpm Average pulling speed: 1.2 mm / min Magnetic field application: cusp magnetic field Magnetic field strength on quartz crucible wall: constant at 1300 gauss Zero magnetic field position: 50 mm below melt surface position Artificial fluctuation of growth rate at interface: Yes Artificial fluctuation of melt temperature at solid-liquid interface: Yes Interval of fluctuation: 5.2mm Wafer is cut out from ingot grown under these conditions, oxygen concentration, impurities (boron) Tables 1 to 3 show the results of measurement of the distribution of the concentration and COP and the result of the reliability test of the gate oxide film.

EXAMPLE 9 Using the apparatus shown in FIG. 2, a P-type (boron-doped) silicon single crystal ingot having a diameter of 8 inches was grown under the following conditions.

Absorption layer of point defect: Yes Stable hot zone: Yes Single crystal rotation speed: 18 rpm constant Crucible rotation speed: 6 rpm constant Average pulling speed: 0.9 mm / min Magnetic field application: Cusp magnetic field Quartz crucible wall Magnetic field intensity: The operation of decreasing from 400 Gauss to 300 Gauss in 115 seconds, holding at 300 Gauss for 40 seconds, and periodically increasing from 300 Gauss to 400 Gauss in 115 seconds Zero magnetic field position: From melt surface position Fluctuation of growth rate at solid-liquid interface: Yes Fluctuation of melt temperature at solid-liquid interface: Yes Fluctuation interval: 6.0 mm Wafer is cut out from ingot grown under these conditions, oxygen concentration, impurities (boron) Tables 1 to 3 show the results of measurement of the distribution of the concentration and COP and the result of the reliability test of the gate oxide film.

Example 10 Using the apparatus shown in FIG. 2, a P-type (boron-doped) silicon single crystal ingot having a diameter of 8 inches was grown under the following conditions.

Absorption layer of point defect: Yes Stable hot zone: Yes Rotation speed of single crystal: constant at 18 rpm Rotation speed of crucible: constant at 7 rpm Average pulling speed: 1.0 mm / min Magnetic field application: cusp magnetic field on quartz crucible wall Magnetic field strength: 1000 Gauss Zero magnetic field position: 50 mm from 40 mm below the melt surface
Downward in 115 seconds, after holding at this position for 40 seconds, periodically performing operation of raising from 50 mm below to 40 mm below in 115 seconds Artificial fluctuation of growth rate at solid-liquid interface: Yes Solid-liquid interface Variation of melt temperature in GaN: Yes Interval of fluctuation: 7.0mm Wafer is cut out from ingot grown under these conditions, measurement of oxygen concentration, impurity (boron) concentration and distribution of COP and reliability of gate oxide film The results of the sex test are shown in Tables 1 to 3.

Example 11 Using the apparatus shown in FIG. 3, a P-type (boron-doped) silicon single crystal ingot having a diameter of 8 inches was grown under the following conditions.

Absorption layer for point defect: Yes Stable hot zone: Yes Rotation speed of single crystal: Decrease from 18 rpm to 1 rpm in 2 seconds, hold at 1 rpm for 20 seconds, then increase from 1 rpm to 18 rpm in 2 seconds Rotational speed of crucible: constant at 4 rpm Average pulling speed: 1.0 mm / min Magnetic field application: horizontal magnetic field Strength of magnetic field on quartz crucible wall: constant at 3000 gauss Artificial fluctuation of growth rate at solid-liquid interface: yes Artificial fluctuation of melt temperature at solid-liquid interface: Yes Fluctuation interval: 8.0 mm Wafer is cut out from ingot grown under these conditions, measurement of oxygen concentration, impurity (boron) concentration and distribution of COP and gate oxidation Tables 1 to 3 show the results of the reliability test of the film.

Example 12 Using the apparatus of FIG. 3, a P-type (boron-doped) silicon single crystal ingot having a diameter of 8 inches was grown under the following conditions.

Absorption layer of point defect: Yes Stable hot zone: Yes Rotation speed of single crystal: Constant 18 rpm Rotation speed of crucible: Constant 1.5 rpm Average pulling speed: 1.0 mm / min Magnetic field application: Cusp magnetic field Quartz crucible wall Field strength at 2,000 Gauss to 1500
Decrease to Gauss in 115 seconds, 60 at 1500 Gauss
After holding for 2 seconds, the operation of increasing from 1500 Gauss to 2000 Gauss in 115 seconds is periodically performed. Artificial fluctuation of growth rate at solid-liquid interface: Yes Artificial fluctuation of melt temperature at solid-liquid interface: Yes Fluctuation Spacing: 8.0 mm A wafer was cut out from an ingot grown under these conditions, and the results of measurement of the oxygen concentration, impurity (boron) concentration and distribution of COP, and the reliability test of the gate oxide film were performed. Show.

(Comparative Example 1) Using the apparatus of FIG. 1, a P-type (boron-doped) silicon single crystal ingot having a diameter of 8 inches was grown under the following conditions.

Absorption layer of point defect: No Stable hot zone: Yes Single crystal rotation speed: 30 rpm constant Crucible rotation speed: 10 rpm constant Average pulling speed: 0.8 mm / min Artificial growth rate at solid-liquid interface Fluctuation: None Artificial variation of melt temperature at solid-liquid interface: None Fluctuation interval: None Wafers were cut out from ingots grown under these conditions, and oxygen concentration, impurity (boron) concentration and COP distribution were measured and gated. Tables 1 to 3 show the results of the reliability test of the oxide film.

Comparative Example 2 Using the apparatus shown in FIG. 2, a P-type (boron-doped) silicon single crystal ingot having a diameter of 8 inches was grown under the following conditions.

Absorption layer of point defect: None Stable hot zone: None Rotational speed of single crystal: Constant 25 rpm Rotational speed of crucible: Constant 6 rpm Average pulling speed: 0.8 mm / min Magnetic field application: Cusp magnetic field Quartz crucible wall Magnetic field strength: constant at 1000 Gauss Zero magnetic field position: 40 mm below the melt surface position Artificial fluctuation of growth rate at solid-liquid interface: none Artificial fluctuation of melt temperature at solid-liquid interface: none Interval of fluctuation: none Tables 1 to 3 show the results obtained by cutting a wafer from the ingot grown under the conditions, measuring the oxygen concentration, the impurity (boron) concentration, the distribution of COP, and conducting a reliability test of the gate oxide film.

Comparative Example 3 Using the apparatus of FIG. 3, a P-type (boron-doped) silicon single crystal ingot having a diameter of 8 inches was grown under the following conditions.

Absorption layer of point defect: None Stable hot zone: None Rotation speed of single crystal: constant at 18 rpm Rotation speed of crucible: constant at 1 rpm Average pulling speed: 0.9 mm / min Magnetic field application: horizontal magnetic field at quartz crucible wall Magnetic field strength: Constant 3000 Gauss Artificial fluctuation of growth rate at solid-liquid interface: None Artificial fluctuation of melt temperature at solid-liquid interface: None Interval of fluctuation: None Wafer is cut out from ingot grown under these conditions and oxygen Tables 1 to 3 show the results of measurement of the concentration, the impurity (boron) concentration, and the distribution of COP, and the results of a reliability test of the gate oxide film.

[0089]

[Table 1]

[0090]

[Table 2]

[0091]

[Table 3]

As is evident from these results, in the embodiment of the present invention, the distribution state of each of the oxygen concentration, the impurity concentration, and the COP shows a unique form, and the pass rate of the reliability test is 60 for each wafer. % Or less, with few crystal defects,
The wafer was found to be suitable for semiconductor device manufacturing. In particular, when all of the oxygen concentration, the impurity concentration, and the COP show a clear distribution form, the pass rate of the reliability test is 7%.
0% or more, which proved that the wafer had very few crystal defects and was suitable for semiconductor device production.

On the other hand, in the comparative example, since no artificial fluctuation was added, all of the oxygen concentration, the impurity concentration, and the COP were uniformly distributed (disk-shaped) over the entire surface of the wafer, and the pass rate of the reliability test was Of 10% or less, indicating that the wafer had extremely many crystal defects and was not suitable for manufacturing semiconductor devices.

[0094]

The silicon single crystal wafer of the present invention has a C
Since there are few grown-in defects such as OPs, when this wafer is used for a semiconductor device, the production yield of the semiconductor device can be improved. In addition, since the method for manufacturing a silicon single crystal wafer of the present invention can be applied to a conventional silicon single crystal manufacturing apparatus without modification, a high-quality silicon single crystal wafer can be produced at a high yield without increasing the manufacturing cost. Can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a Cz method silicon single crystal manufacturing apparatus used in Examples 1 to 7 and Comparative Example 1.

FIG. 2 is a schematic view of a cusp magnetic field applied Cz silicon single crystal manufacturing apparatus used in Examples 8 to 10 and Comparative Example 2.

FIG. 3 is a schematic view of a horizontal magnetic field applied Cz silicon single crystal manufacturing apparatus used in Examples 11 to 12 and Comparative Example 3.

FIG. 4 is a schematic view of an artificial variation in crystal rotation in Example 11.

FIG. 5 is an example of an impurity concentration fluctuation distribution in an 8-in wafer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cz dislocation-free silicon single crystal pulling furnace 2 ... wire winding machine 3 ... heat insulating material 4 ... heating heater 5 ... rotating jig 6 ... crucible 6a ... quartz crucible 6b ... graphite crucible 7 ... wire 8 ... seed crystal 9 ... Chuck 10 Gas inlet 11 Gas outlet 20 Coaxial opposed electromagnet for applying cusp magnetic field 30 Electromagnet for applying horizontal magnetic field

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshio Iwasaki 3434 Shimada, Hikari-shi, Yamaguchi Pref.Nitetsu Electronics Co., Ltd. (72) Inventor Hirofumi Harada 3434 Shimada, Hikari-shi, Hikari-shi Yamaguchi Pref. 72) Inventor Atsushi Fukuda 3434 Shimada, Hikari-shi, Yamaguchi Prefecture Inside Nittetsu Electronics Co., Ltd. (72) Inventor Masami Hasebe 3-35-1 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture New Nippon Steel Corporation Technology Development Headquarters

Claims (16)

[Claims] 1. A silicon single crystal wafer obtained from a silicon single crystal grown by the Czochralski method, wherein the in-plane distribution of COP, oxygen concentration and / or impurity concentration found in the wafer is concentric. A silicon single crystal wafer in one or more forms of spiral and radial. 2. The silicon single crystal wafer according to claim 1, wherein in the form of the in-plane distribution of the wafer, the interval is 1 mm or more. 3. The silicon single crystal wafer,
The area density of COP of 0.10 μm or more in terms of diameter is
1.6 wafers / cm on average over the entire wafer area ^TwoBelow
The silicon single crystal wafer according to claim 1. 4. In the silicon single crystal wafer,
The silicon single crystal wafer according to any one of claims 1 to 3, wherein the area of the region where the COP does not exist is 20% or more of the entire area of the wafer. 5. A method for producing a silicon single crystal wafer by the Czochralski method, wherein a point defect absorption layer is formed in the single crystal during the growth of the silicon single crystal. Method. 6. A fluctuation of a single crystal growth rate at a solid-liquid interface during growth of the silicon single crystal or a fluctuation of an oxygen concentration and / or an impurity concentration due to a fluctuation of a melt temperature at the solid-liquid interface is less than 5%. The method for manufacturing a silicon single crystal wafer according to claim 5, wherein the silicon single crystal is grown in a hot zone. 7. The method according to claim 1, wherein the fluctuation of the single crystal growth rate at the solid-liquid interface during the growth of the silicon single crystal or the fluctuation of the oxygen concentration and / or the impurity concentration due to the fluctuation of the melt temperature at the solid-liquid interface is continuously or The method for manufacturing a silicon single crystal wafer according to claim 5, wherein the point defect absorbing layer is formed in the single crystal by adding 5% at a maximum periodically. 8. The production of a silicon single crystal wafer according to claim 7, wherein the variation applied continuously or periodically with the growth of the silicon single crystal is an interval of 0.5 mm or more in the pulling direction of the single crystal. Method. 9. The method of manufacturing a silicon single crystal wafer according to claim 7, wherein the change is to change the rotation speed of the single crystal or the crucible continuously or periodically. 10. The method according to claim 1, wherein the variation is such that the rotation speed of the single crystal is 200 when the diameter of the silicon single crystal is D (in).
0 / D ² to 600 / D ² (rpm) to 300 / D ^{2 to} 0
(Rpm) to transition time is reduced by 2 minutes 1 second, subsequently after train 1 second to 1 minute single crystal at a rotational speed of the 300 / D ² ~0 single crystal (rpm), the rotation speed of the single crystal 2
Transition time from 000 / D ² to 600 / D ² (rpm) 2 minutes
10. The method of manufacturing a silicon single crystal wafer according to claim 9, wherein the increase is performed in one second. 11. The method for manufacturing a silicon single crystal wafer according to claim 7, wherein the pulling speed of the silicon single crystal is continuously or periodically changed. 12. The method for producing a silicon single crystal wafer according to claim 5, wherein a magnetic field is applied to the melt during the growth of the silicon single crystal. 13. The method of manufacturing a silicon single crystal wafer according to claim 12, wherein the application of the magnetic field is an application of a cusp magnetic field of 100 gauss or more on the wall of the quartz crucible containing the melt. 14. The method for manufacturing a silicon single crystal wafer according to claim 13, wherein the magnetic field strength of the cusp magnetic field or the zero magnetic field position is changed continuously or periodically. 15. The method for producing a silicon single crystal wafer according to claim 12, wherein the application of the magnetic field is an application of a horizontal magnetic field of 500 gauss or more on the wall of the quartz crucible containing the melt. 16. The method for manufacturing a silicon single crystal wafer according to claim 15, wherein the magnetic field strength of the horizontal magnetic field is changed continuously or periodically.