JPH11130593A - High-quality silicon single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high-quality silicon single crystal grown by Czochralski process (hereinafter referred to as CZ process). SOLUTION: In this high-quality silicon single crystal grown by CZ process, the width of R-OSF (ring-like oxidation induced stacking fault which appears in the crystal face) exceeds 8% of radium of grown crystal and is free from defect of a dislocation cluster. Observation of the above R-OSF is carried out by immersing wafer processed from a single crystal in As-grown state into Cu solution to attach Cu to the wafer, subjecting the wafer to Cu decoration heat treatment at 900 deg.C for 20 min, charging wafer processed from a single crystal in As-grown state into a heat-treating furnace at 650 deg.C, raising the temperature of the wafer at a rate of <=8 deg.C/min after charging, subjecting the wafer to heat treatment at 900 deg.C for 20 hr and at 1,000 deg.C for 10 hr and observing distribution of deposition of oxygen by X ray topograph. Since the crystal in-plane is formed as the region free from infrared beam scatterer and dislocation claster, a semiconductor material excellent in device characteristic can be fed.

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 used as a semiconductor material, and more particularly to a high-quality silicon single crystal grown by the Czochralski method (hereinafter referred to as CZ method). .

[0002]

2. Description of the Related Art There are various methods for growing a silicon single crystal used for a semiconductor material. Among them, the CZ method is a growing method widely used.

FIG. 1 is a schematic sectional view of a single crystal growing apparatus used for growing a single crystal by the ordinary CZ method. As shown in FIG. 1, the crucible 1 has a bottomed cylindrical inner holding container 1a made of quartz, and a cylindrical outer bottom holding container 1b made of graphite fitted to the outside of the inner holding container 1a. It is composed of Crucible 1 having such a configuration
Is supported by a support shaft 1c that rotates at a predetermined speed, and a heater 2 is concentrically arranged outside the crucible 1 in a cylindrical shape. The inside of the crucible 1 is filled with a melt 3 of a raw material melted by the heating of the heater 2, and a pulling shaft 4 made of a pulling rod or a wire is disposed at the center of the crucible 1. . A seed chuck and a seed crystal 5 are attached to the tip of the pulling shaft 4. The seed crystal 5 is brought into contact with the surface of the melt 3 to grow a single crystal 6. Further, the lifting shaft 4 is supported by the support shaft 1c.
The seed crystal 5 is pulled up while rotating at a predetermined speed in a direction opposite to the crucible 1 rotated by the above, so that the melt 3 is solidified at the tip of the seed crystal 5 to grow the single crystal 6.

[0004] In growing a single crystal, a seed drawing is first performed in order to eliminate dislocations in the crystal. After that, in order to secure the body diameter of the single crystal, a shoulder is formed, and when the body diameter is reached, the shoulder is changed, and the body diameter is made constant to shift to the growth of the single crystal body. When a single crystal having a body diameter and a predetermined length is grown, til drawing is performed to separate the single crystal from the melt without dislocation. after that,
The single crystal separated from the melt is taken out of the growing apparatus, cooled under predetermined conditions, and processed into a wafer.
The wafer processed from the single crystal in this way is used as a substrate material for various devices.

[0005] In the plane of a single crystal or a processed wafer grown through the above-described steps, a ring-shaped oxidation-induced stacking fault (hereinafter referred to as R-OSF (Ox
idation induced Stacking Fault). In addition, several types of minute defects (hereinafter referred to as “Grown-in defects”) are formed in the plane. This Grow
The n-in defect is a crystal defect formed at the time of growing a single crystal, and is detected at a subsequent wafer evaluation stage.

FIG. 2 is a diagram schematically illustrating the general relationship between the pulling speed during the growth of a single crystal and the position where a crystal defect occurs. As shown in the figure, the region where R-OSF is generated is affected by the pulling speed (mm / min) during growth, and as the pulling speed is reduced, the region where R-OSF appears appears from the outer periphery of the crystal. Shrink inward. In other words, when growing a single crystal at high speed, the crystal in the region inside the R-OSF will spread over the entire wafer, and when growing at a low speed, the crystal in the region outside the R-OSF will spread over the entire wafer.

Crystal properties are different between the inner region and the outer region of the R-OSF, and the detected Grown-in defect is also different. R-OSF
An infrared scatterer (which may be simply referred to as FPD) is detected in the region inside the, and a defect called a dislocation cluster is detected in the region outside the R-OSF. For example, when a ring portion of the R-OSF is generated in the wafer surface, an infrared scatterer is detected in an inner region of the R-OSF and a dislocation cluster is detected in an outer region, but as shown in FIG. Gro in the outer area close to the OSF
There is a defect-free area where no wn-in defect is detected.

[0008]

The above-mentioned oxidation-induced stacking faults are interstitial type dislocation loops generated during the oxidation heat treatment, and cause leakage current when formed and grown on the wafer surface which becomes the active region of the device. Therefore, it becomes a defect that degrades device characteristics. For this reason, R-OSF generated in the wafer surface during the growth of the single crystal is controlled.

Usually, in order to reduce the generation of R-OSF in the wafer plane, a single crystal is grown under pulling conditions that limit the region where R-OSF is generated to the outer peripheral portion of the wafer. However, the region where R-OSF is generated is determined not only by the pulling rate but also by the temperature range of the hottest part (melting point to 1200 ° C) during single crystal growth, and is affected by the heat history at the hottest part during pulling. Has been confirmed. Therefore, in determining the region where R-OSF is generated, attention must be paid to the temperature gradient and the pulling rate at the highest temperature in the pulling axis direction of the single crystal to be grown. That is, reducing the temperature gradient when the pulling speed is the same, or increasing the pulling speed when the temperature gradient is the same limits the R-OSF generation region to the outer peripheral portion of the wafer.

[0010] In order to confirm the position and width of the R-OSF generated in the wafer surface, a wafer processed from an as-grown single crystal is immersed in a Cu solution, Cu is attached, and 900 ° C. × 2
It is effective to perform Cu decoration heat treatment for 0 min and observe the defect distribution by X-ray topography. In addition, to confirm the position and width of R-OSF when the crystal has low oxygen concentration, a wafer processed from a single crystal in the as-grown state is placed in a heat treatment furnace at 650 ° C, and 8 ℃ /
It is effective to observe the state distribution of oxygen precipitation by X-ray topography after heat treatment at 900 ° C × 20 hours and 1000 ° C × 10 hours by raising the temperature below min and examine the region where the amount of ring-shaped oxygen precipitation is small. It is.

Recently, as the temperature of the device process is lowered and the grown single crystal is reduced in oxygen, the adverse effect of the R-OSF on the device is suppressed, and the deterioration of the device characteristics due to the oxidation-induced stacking fault becomes a serious problem. No longer. In contrast, among the Grown-in defects, infrared scatterers are factors that deteriorate the initial oxide film breakdown voltage characteristics, and dislocation clusters are factors that significantly degrade device characteristics. It becomes more important to reduce the in-plane density. The region where the density of the Grown-in defect is low corresponds to a defect-free region close to the above-mentioned R-OSF, but the region is limited and is limited to a very narrow region.

Conventionally, various methods have been proposed to reduce the density of grown-in defects in a wafer surface. For example, in Japanese Patent Application Laid-Open No. 8-330316, a method in which the pulling rate during growing a single crystal and the temperature gradient in the crystal are controlled, and without dislocation clusters being generated, only the outer region of the R-OSF is spread over the entire crystal surface. Has been proposed. However, the proposed method requires extremely limited in-plane temperature gradients and pulling conditions at the same time, so new improvements are required in the growth of silicon single crystals, which are required to have larger diameters and mass production. Is done.

JP-A-7-257991 and Journal of
Crystal Growth 151, (1995) pp. 273-277, it is possible to make R-OSF disappear inside the crystal under high-speed pulling conditions by increasing the temperature gradient in the pulling axis direction of the single crystal. A method for forming an outer region over the entire surface of a crystal is disclosed. However, in the methods disclosed therein, no consideration is given to the distribution of the temperature gradient in the crystal plane, that is, the uniformity of the temperature distribution in the wafer plane and the uniformization of the point defects to be taken in the plane. In other words, no consideration has been given to the means of reducing Grown-in defects in the wafer plane, and even if the R-OSF is simply shrunk inward, dislocation clusters are observed on the wafer plane only in the conventional crystal. Is the same as Therefore, even with the disclosed method, it is not possible to process a wafer corresponding to low density of Grwon-in defects.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems relating to the conventional crystal defects, and has a structure in which Gr
The purpose of the present invention is to provide a high-quality silicon single crystal in which a region without an infrared scatterer or dislocation cluster, which is an own-in defect, can be enlarged and a diameter and a length can be increased during growth.

[0015]

Means for Solving the Problems In order to solve the above problems, the present inventors have improved the conditions for growing a single crystal by the CZ method, and although R-OSF is generated in the wafer surface, OSF
In addition, various investigations were made with an eye on expanding a defect-free region existing in the vicinity of the outside region to a wide region of the wafer.

First, R-
We investigated the occurrence of dislocation clusters with respect to the location and width of OSF. In order to clarify the position of R-OSF generation in the wafer plane, the distance (radius) from the center to the outer periphery of the crystal (wafer) is R, and the R-OSF in the radial direction of the crystal is
Where r occurs at the center of the crystal and r
= 0, and the case where it occurs on the outer periphery of the crystal is indicated by r = R. However, the position where the R-OSF is generated is indicated by its inner diameter position.

FIG. 3 shows an 8 ″ grown under conventional growing conditions.
FIG. 4 is a diagram schematically showing a relationship between a radial position where R-OSF is generated, a width of R-OSF, and a dislocation cluster generation state in a crystal of φ (the width of R-OSF on the horizontal axis is%. Shown). Numerous investigations have revealed that the width of R-OSF is less than 8% of its radius in crystals grown under conventional growth conditions. In FIG. 3, when the width of the R-OSF is 8% of the radius of the grown crystal and the R-OSF generation position is r = ｒR, dislocation clusters are observed in the region outside the R-OSF. It is shown that. Therefore, the position of R-OSF is r = 2
When they occur on the center side from / 3R, dislocation clusters are observed in the region outside the R-OSF. Also, it can be seen that dislocation clusters are more easily observed as the width of the R-OSF becomes smaller.

The width of R-OSF of the grown crystal is 8% of the radius.
In the following cases, the density of the infrared scatterers in the region inside the R-OSF can be reduced by shrinking the generation position of the R-OSF toward the center. For this reason, the initial breakdown voltage characteristic (TZDB) of the oxide film can be improved, but the characteristic is deteriorated by dislocation clusters generated in the outer region of the R-OSF, which is not suitable as a device substrate material.

Next, as will be described later, R-crystals of diameters 6 ″ φ and 8 ″ φ grown under improved growth conditions were used.
We investigated the location and width of OSF and the occurrence of dislocation clusters.

FIG. 4 is a schematic diagram showing the relationship between the radial position where R-OSF occurs, the width of R-OSF, and the state of dislocation cluster generation in an 8 ″ φ crystal grown under improved growth conditions. (The width of the R-OSF on the horizontal axis is shown in%.) Under the improved growth conditions, the width of the R-OSF can be increased, and the region where dislocation clusters do not occur can be enlarged. For example, in FIG.
It can be seen that when the OSF width is 30% of the crystal diameter, dislocation clusters do not occur regardless of the R-OSF generation position.

FIG. 6 to be described later is a diagram showing the relationship between the in-plane position of R-OSF and the distribution density of FPD defects in the as-grown crystal grown by the method of the first embodiment. In other words, the width of R-OSF exceeds 39% of the radius of the grown crystal.
FIG. 11 is a diagram showing the FPD density in a plane of a wafer where dislocation clusters were not generated when the position of the R-OSF was changed when the R-OSF was changed to about (diameter 6 ″ φ and the width of the R-OSF was 30 mm). As shown in the figure, when the width of the R-OSF increases, the R-OSF generation position may be observed at the center at r = 2 / 3R. Observed when = 1 / 3R
FPD is completely gone.

FIG. 9 to be described later is a diagram showing the relationship between the in-plane position of the R-OSF and the distribution density of FPD defects in the as-grown crystal grown by the method of the third embodiment. As in 6, the width of the R-OSF is about 39% of the radius of the grown crystal (the diameter of the R-OSF is 8 mm and the width of the R-OSF is 40 mm), and dislocation clusters are generated when the position of the R-OSF is changed. This figure shows the in-plane FPD density of the unwafered wafers.As is clear from the figure, when the width of the R-OSF increases, it is observed in the region inside the R-OSF depending on the position where the R-OSF occurs. As described above, when the width of the R-OSF is large, dislocation clusters do not occur, the density of the infrared scatterers in the region inside the R-OSF is extremely low, and further conditions are added. This can eliminate the generation of infrared scatterers.

According to the study of the present inventors, it is necessary to reduce the width of the R-OSF to reduce or eliminate the Grown-in defects from the crystal plane without generating dislocation clusters and infrared scatterers in the wafer plane. And the position where R-OSF is generated must be within the range of 0 to 80% of the diameter. Here, as described above, the generation position of the R-OSF is represented by the inner diameter of the R-OSF.

Therefore, compared to the conventional crystal, R-OSF
Is located on the center side in the wafer plane, but the width of the R-OSF is large, so the defect-free area is
No dislocation cluster exists in the outer region of F and R-OSF
No infrared scatterer is observed even in the region inside. As described above, since the occurrence of the Grown-in defect that degrades the device characteristics in the entire region on the wafer surface can be suppressed, the non-defective product rate can be greatly improved.

The present invention has been completed based on the above findings, and has as its gist the following high-quality silicon single crystals (1) to (4).

(1) A silicon single crystal grown by the CZ method, which has been processed from an as-grown single crystal, is immersed in a Cu solution, and Cu is deposited thereon.
When subjected to Cu decoration heat treatment and observed with an X-ray topograph, the width of ring-shaped oxidation-induced stacking faults appearing in the crystal plane exceeds 8% of the radius of the grown crystal, and there is no dislocation cluster defect. High quality silicon single crystal.

(2) A silicon single crystal grown by the CZ method, which has been processed from an as-grown single crystal, is immersed in a Cu solution, and Cu is adhered thereto.
When a Cu decoration heat treatment is performed and observed with an X-ray topograph, the width of the ring-shaped oxidation-induced stacking faults appearing in the crystal plane exceeds 8% of the radius of the grown crystal, and the ring-shaped oxidation-induced stacking fault is observed. A high-quality silicon single crystal characterized in that the inside diameter of the defect is included in the range of 0 to 80% of the diameter of the grown crystal, and the density of the Grown-in defect is low or absent.

(3) A silicon single crystal grown by the CZ method, which has been processed from an as-grown single crystal, is charged into a heat treatment furnace at 650 ° C., and 8 ° C./min after the charging.
After heating at 900 ° C for 20 hours and 1000 ° C for 10 hours, the distribution of oxygen precipitation was observed by X-ray topography, and the width of ring-shaped oxidation-induced stacking faults appearing in the crystal plane grew. A high quality silicon single crystal characterized by having no dislocation cluster defects exceeding 8% of the radius of the crystal obtained.

(4) A silicon single crystal grown by the CZ method, which has been processed from an as-grown single crystal, is charged into a heat treatment furnace at 650 ° C., and 8 ° C./min after the charging.
After heating at 900 ° C for 20 hours and 1000 ° C for 10 hours, the distribution of oxygen precipitation was observed by X-ray topography, and the width of ring-shaped oxidation-induced stacking faults appearing in the crystal plane grew. Exceeding 8% of the radius of the grown crystal, and the inner diameter of the ring-shaped oxidation-induced stacking fault is included in the range of 0 to 80% of the diameter of the grown crystal, and the density of the grown-in defect is low or no. High quality silicon single crystal characterized by the following.

In the high quality silicon single crystal of the present invention,
The width of the R-OSF is defined to exceed 8% of the radius of the grown crystal. Conventionally, when the width of the R-OSF is 8% or less, dislocation clusters are formed at r = 2 / 3R. Although the width of the R-OSF exceeds 8% by application of the present invention, r = 2
This is because dislocation clusters do not appear even if the shrinkage is reduced to / 3R or less.

The reason why the R-OSF generation position is defined in the range of 0 to 80% of the grown crystal diameter is that if it is within this range, the growth-in defects are extremely reduced, Or it can be eliminated. For example, the smaller the value of r, the lower the density of Grown-in defects, and r = 1 / 3R
The Grown-in defect is not detected below. Therefore, in the silicon single crystal of the present invention, the Grown-in defects are significantly reduced as compared with the conventional whole crystal inside the R-OSF, and in the above (2) and (4), Grow
The density of n-in defects is defined as "low density or no density".

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION In order to produce a high quality silicon single crystal of the present invention, the thermal history of the highest temperature part (melting point to 1200 ° C.) of the single crystal is controlled during the growth by the CZ method. It is necessary to make the concentration of point defects incorporated in the plane of the crystal uniform in the plane. Point defects in the crystal are between vacancies and lattices
Although classified as Si atoms, the generation of R-OSF is strongly related to vacancies, and the position and width of R-OSF generated in the plane have a limited range of vacancy concentration sites and regions. Matches.

Normally, when growing a single crystal, the temperature gradient in the direction of the pulling axis in the plane of the crystal is different. Specifically, since the temperature decreases faster at the outer peripheral portion of the crystal, the temperature gradient increases at the outer peripheral portion. In this case, if the temperature gradient increases, the amount of vacancies taken into the crystal diffuses toward the solid-liquid interface side in the pulling axis direction and disappears, and the concentration of vacancies taken into the crystal increases. Significantly reduced. As a result, if the temperature gradient in the direction of the pulling axis is different,
The concentration of vacancies taken into the crystal plane is not uniform, and the density decreases toward the outer periphery of the crystal. Therefore, by making the temperature gradient uniform in the direction of the pulling axis in the plane of the crystal, the vacancy concentration in the plane can be made uniform.

FIG. 5 is a diagram schematically showing the relationship between the concentration distribution of vacancies taken into the plane of the crystal and the width of the generated R-OSF. The vertical axis in the figure indicates the vacancy concentration Cv, and the horizontal axis indicates the position in the crystal plane. Also, the left side of the figure shows the case where the variation of the hole concentration from the center in the plane to the outer periphery is large,
The right side of the figure shows the case where the vacancy concentration is relatively uniform. Since the region where the R-OSF occurs coincides with the region of the vacancy concentration in the limited range, when the vacancy concentration becomes uniform in the plane as shown on the right side of FIG.
The width of R-OSF increases. As described above, the width of the in-plane R-OSF in the conventional crystal is suppressed to 8% or less of the grown crystal radius. This is because under the conventional growth conditions, the temperature gradient in the direction of the pulling axis in the plane of the crystal is not uniform, so that the range of the vacancy concentration corresponding to the region where the R-OSF occurs is 8% of the radius of the grown crystal. Because it was within the range.

By improving the growth conditions, for example, by improving the heating means and the heat retaining member of the hot zone in the single crystal growth apparatus, the temperature gradient in the direction of the pulling axis in the plane of the crystal is made uniform. In addition, the incorporation amount of holes is made uniform in the plane. Accordingly, the range of the vacancy concentration in which the R-OSF is generated can be expanded, and the width of the R-OSF can be correspondingly increased. In addition, the defect-free region existing in the outer region close to the R-OSF can also be obtained by increasing the range of the concentration of vacancies in which the defect-free region is generated by making the amount of vacancies taken in the plane uniform. , The area can be enlarged. As a result, a region in which a Grown-in defect such as an infrared scatterer or dislocation cluster that deteriorates the device characteristics is not generated is expanded to the entire in-plane of the crystal, and a high-quality wafer having good device characteristics can be obtained.

[0036]

EXAMPLES The silicon single crystal of the present invention was manufactured in two dimensions of 6 ″ φ and 8 ″ φ in diameter, and the morphology of R-OSF and the quality characteristics of the crystal were examined. Hereinafter, the results will be described.

Example 1 A single crystal of 6 ″ φ is manufactured by using the single crystal growing apparatus shown in FIG. 1. A crucible is filled with 60 kg of polycrystalline silicon as a raw material for the crystal, and the electric resistivity is further increased. Then, boron is added as a P-type dopant so that the pressure becomes 10 Ωcm, and after the inside of the chamber is set to an Ar atmosphere of 10 Torr, the power of the heater is adjusted to melt all the raw materials for crystallization. After stabilization, the lower end of the seed crystal is immersed in the melt, and the single crystal is pulled while rotating the crucible and the pulling shaft.

The purpose of the first embodiment is to investigate how the width of the R-OSF and the defect-free region or the FPD density changes depending on the growth conditions. For this reason,
Growing in a hot zone in which the temperature distribution in the crystal plane is improved compared to the conventional one, so that the rate of crystal growth is gradually reduced so that the incorporation of vacancies into the crystal plane becomes uniform. A speed change experiment was performed.

Therefore, the growth of the single crystal shifts from seed drawing and shoulder formation, and after moving to the body, the heater power is adjusted, the pulling speed is initially increased, and a predetermined value is set under the condition that the R-OSF is generated on the outer periphery. The crystal length of is increased. When the pulling length of the single crystal reaches 100 mm, the pulling speed of the crystal is gradually reduced, and the morphology of the R-OSF and defect-free regions and the behavior of FPD defects generated in the inner region of the R-OSF investigated.

The As-gro grown by the method of Example 1
The crystals in the wn state were vertically divided, Cu was applied, and heat treatment was performed at 900 ° C. to clarify each defect region. Then, an X-ray topographic photograph was taken to examine the morphology of the R-OSF. Compared with the conventional crystal, the width of the R-OSF and the defect-free area are greatly expanded, and the width of the R-OSF generated in the plane in the circumference is 30 m on one side
m, but expanded to a maximum of 40 mm, 80 mm for both
Some parts are marked with. In other words, there are portions where more than half (52%) of the radius of the 6 ″ φ crystal corresponds to the width of the R-OSF. In addition, the R-OSF is generated at the center of the crystal, and the outer region of the R-OSF expands. However, it was also confirmed that the defect-free region was greatly expanded and no dislocation cluster was observed.

FIG. 6 is a diagram showing the relationship between the in-plane position of the R-OSF and the distribution density of FPD defects in the as-grown crystal grown by the method of the first embodiment. However, R-OSF
Seco etching was performed to observe the in-plane position. The width of the R-OSF was 30 mm, which was about 39% of the crystal radius. As is clear from the figure, the position of the R-OSF in the plane is r = 2/3.
In the case of R, FPD defects are observed at the center of the crystal, but when r = 1 / 3R, no FPD defects are observed. Therefore, by adjusting the growth conditions and controlling the width and in-plane position of the R-OSF, a crystal in which no infrared scatterer (FPD) or a Grown-in defect of a dislocation cluster is observed in the plane of the crystal is grown. be able to.

FIG. 7 shows an initial oxide film breakdown voltage characteristic of a wafer processed from the single crystal manufactured by the method of Example 1.
FIG. 9 is a diagram showing the results of investigating (TZDB). That is, R-
The figure shows the average non-defective rate at the position where the R-OSF exists when the position where the R-OSF is generated is changed from the center to the outer periphery of the wafer when the width of the OSF is 30 mm. The figure shows that the oxide film thickness is 25.
When the R-OSF position is r = 1 / 3R and the FPD density is very small, the yield rate of TZDB in the crystal plane is 95
% Or more.

Example 2 In Example 2, the growth was performed at a pulling rate at which the in-plane position of the R-OSF of the 6 ″ φ crystal was r = 1 / 3R, and the R-OSF, the defect-free region, and the FPD were grown. We investigated how the density changes with growing conditions,
The growth was performed in the same hot zone as in Example 1 so that the amount of vacancies taken into the crystal plane was uniform.

After stabilizing the melt in the crucible under the same conditions as in Example 1, the growth of the single crystal was shifted from seed drawing and shoulder formation, and after moving to the body, the heater power was adjusted. Is fast, and a predetermined crystal length is pulled under the condition that R-OSF is generated on the outer periphery. When the pulled length of the single crystal reaches 100 mm, the in-plane position of the R-OSF is r = 1 /
Growing at a pull rate of 3R, RO
FPD generated in SF, defect-free area and area inside R-OSF
The behavior of the defect was investigated.

The As-gro grown by the method of Example 2
Apply Cu to the wafer processed from the single crystal in the wn state,
After heat treatment at 900 ° C to reveal each defect area, an X-ray topograph was taken to show the morphology of R-OSF and Grown-in
The status of the defect was investigated. The width of the generated R-OSF is 30mm
It was confirmed that the inner diameter position of the R-OSF was r = 1 / 3R. From this, it can be seen that the width of the R-OSF and the defect-free region are greatly increased as compared with the conventional crystal.

FIG. 8 is a view showing the distribution density of FPD defects in an as-grown crystal grown by the method of the second embodiment. However, seco etching was performed to observe the in-plane position of the R-OSF. The width of the R-OSF is 30 mm, which is about 39% of the crystal radius. When the in-plane position of the R-OSF is r = 1 / 3R, no FPD defect is observed. Similarly, no dislocation clusters were observed.

Example 3 An 8 ″ φ single crystal was produced using the single crystal growing apparatus shown in FIG. 1. A crucible was filled with 120 kg of polycrystalline silicon as a crystal raw material, and the electric resistivity was further increased. Then, boron is added as a P-type dopant so that the pressure becomes 10 Ωcm, and after the inside of the chamber is set to an Ar atmosphere of 10 Torr, the power of the heater is adjusted to melt all the raw materials for crystallization. After stabilization, the lower end of the seed crystal is immersed in the melt, and the single crystal is pulled while rotating the crucible and the pulling shaft.

First, in order to investigate how the width of the R-OSF and the defect-free region or the FPD density changes depending on the growth conditions, the crystal pulling speed is gradually reduced, as in the first embodiment. An experiment for changing the growth conditions was performed.

Therefore, the growth of the single crystal shifts from seed drawing and shoulder formation, and after moving to the body, the heater power is adjusted. Initially, the pulling speed is high and the predetermined crystal is grown under the condition that R-OSF is generated on the outer periphery. Raise the length. When the pulling length of the single crystal reaches 100 mm, the pulling speed of the crystal is gradually reduced, and the morphology of the R-OSF and the defect-free region,
Furthermore, the behavior of FPD defects generated in the inner region of R-OSF was investigated.

The As-gro grown by the method of Example 3
The crystals in the wn state were vertically divided, Cu was applied, and heat treatment was performed at 900 ° C. to clarify each defect area, and then an X-ray topographic photograph was taken to observe the morphology of the R-OSF and the defect-free area. . The result is similar to the result of Example 1 described above,
Compared with the conventional crystal, the width of the R-OSF and the defect-free region are greatly increased. The width of the R-OSF is up to 40 mm on one side and 80 mm on both sides. That is, 8 ″ φ
Nearly half (39%) of the crystal radius is in the R-OSF region.

FIG. 9 is a diagram showing the relationship between the in-plane position of the R-OSF and the distribution density of FPD defects in an as-grown crystal grown by the method of the third embodiment. However, R-OSF
Seco etching was performed to observe the in-plane position. The width of the R-OSF is 40 mm, which is about 39% of the crystal radius. From the figure, it can be seen that when the position of the R-OSF is r = 2 / 5R, FPD defects are observed at the center of the crystal, but when r = 1 / 3R or less, no FPD defects are observed. . Therefore, by adjusting the growth conditions and controlling the width and in-plane position of the R-OSF, the infrared scatterer (FPD) density in the plane of the crystal is significantly reduced or no longer observed, and dislocation clusters are formed. Crystals in which no Grown-in defects are observed can be grown.

FIG. 10 shows the initial oxide film breakdown voltage characteristics of a wafer processed from the single crystal manufactured by the method of the third embodiment.
FIG. 9 is a diagram showing the results of investigating (TZDB). In the figure, R-
The figure shows the average non-defective rate at the position where the R-OSF exists when the position where the R-OSF is generated is changed from the center to the outer periphery of the wafer when the width of the OSF is 40 mm. The figure shows that the oxide film thickness is 25.
When the R-OSF position is r = 1 / 3R and the FPD density is very small, the yield rate of TZDB in the crystal plane is 95
%.

Example 4 In Example 4, the crystal was grown at a pulling rate such that the in-plane position of the R-OSF of the 8 ″ φ crystal was r = 1 / 3R, and the R-OSF, the defect-free region, and Investigate how the FPD density changes depending on the growth conditions, and use the same hot zone as in Examples 1 and 3 so that the amount of vacancies taken into the crystal plane becomes uniform. Was trained.

After stabilizing the melt in the crucible under the same conditions as in Examples 1 and 3, the single crystal was grown by seed drawing.
After the transition from the shoulder formation to the body, the heater power is adjusted, and the predetermined crystal length is increased under the condition that the pulling speed is initially high and R-OSF is generated on the outer periphery. When the pulling length of the single crystal reaches 100 mm, the R-OSF is grown at a pulling speed at which the in-plane position of the R-OSF becomes r = 1 / 3R until the growing length becomes 1000 mm. The behavior of the FPD defects generated in the OSF, the defect-free area, and the area inside the R-OSF was investigated.

As-growing grown by the method of Example 4
Apply Cu to the wafer processed from the single crystal in the wn state,
After heat treatment at 900 ° C to reveal each defect area, an X-ray topograph was taken to confirm that the width of the R-OSF was 40 mm and the inner diameter position of the R-OSF was r = 1 / 3R. confirmed. As in Example 3 described above, the R-OSF
It can be seen that the width of the region and the defect-free region greatly expanded, and no dislocation cluster was generated.

FIG. 11 is a diagram showing the distribution density of FPD defects in an as-grown crystal grown by the method of the fourth embodiment. However, seco etching was performed to observe the in-plane position of the R-OSF. R-OSF width is 40mm and crystal radius is 3
It is about 9%. When the in-plane position of R-OSF was r = 1 / 3R, no FPD defects and dislocation clusters were observed.

[0057]

According to the high-quality silicon single crystal of the present invention, the width of the R-OSF generated in the plane is enlarged, and the region free of infrared scatterers and dislocation clusters, which are Grown-in defects, is formed. Since it can be enlarged, a semiconductor material having excellent device characteristics can be supplied. In addition, since the single crystal of the present invention is grown by making the concentration of point defects incorporated in the plane of the crystal uniform, the growth and growth of the single crystal can be made large and the manufacturing cost reduced. Thus, improvement of the breeding efficiency is achieved.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a single crystal growing apparatus used for growing a single crystal by a normal CZ method.

FIG. 2 is a diagram schematically illustrating a general relationship between a pulling speed during growing a single crystal and a position where a crystal defect is generated.

FIG. 3 is a diagram schematically showing the relationship between the radial position where R-OSF occurs, the width of R-OSF, and the state of dislocation cluster generation in an 8 ″ φ crystal grown under conventional growth conditions. It is.

FIG. 4 is a diagram schematically showing the relationship between the radial position where R-OSF occurs, the width of R-OSF, and the state of dislocation cluster generation in an 8 ″ φ crystal grown under improved growth conditions. It is.

FIG. 5 is a diagram schematically showing a relationship between a concentration distribution of vacancies taken into a plane of a crystal and a width of generated R-OSF.

FIG. 6 is a view showing the relationship between the in-plane position of R-OSF and the distribution density of FPD defects in an as-grown crystal grown by the method of Example 1.

FIG. 7 is a view showing a result of an investigation on an initial oxide film breakdown voltage characteristic (TZDB) of a wafer processed from a single crystal manufactured by the method of Example 1;

FIG. 8 is a view showing the distribution density of FPD defects in an as-grown crystal grown by the method of Example 2.

FIG. 9 is a diagram showing the relationship between the in-plane position of R-OSF and the distribution density of FPD defects in an as-grown crystal grown by the method of Example 3.

FIG. 10 is a view showing a result of an investigation on an initial oxide film breakdown voltage characteristic (TZDB) of a wafer processed from a single crystal manufactured by the method of Example 3.

FIG. 11 is a diagram showing a distribution density of FPD defects in a crystal in an as-grown state grown by the method of Example 4.

[Explanation of symbols]

 1: Crucible, 1a: Inner layer holding container 1b: Outer layer holding container, 1c: Support shaft 2: Heater, 3: Melt 4: Pulling shaft, 5: Seed crystal 6: Single crystal

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tadami Tanaka 2201 Kamida, Oita, Kihoku-cho, Kishima-gun, Saga Prefecture

Claims (4)

[Claims] 1. A silicon single crystal grown by the Czochralski method, wherein a wafer processed from an as-grown single crystal is immersed in a Cu solution, and Cu is attached to the wafer.
When a Cu decoration heat treatment was performed for 20 minutes and observed by X-ray topography, the width of ring-shaped oxidation-induced stacking faults appearing in the crystal plane exceeded 8% of the radius of the grown crystal, and there were no dislocation cluster defects. High quality silicon single crystal characterized by the following. 2. A silicon single crystal grown by the Czochralski method, wherein a wafer processed from an as-grown single crystal is immersed in a Cu solution, Cu is attached, and 900 ° C.
When performing a Cu decoration heat treatment of × 20 min and observing with an X-ray topograph, the width of the ring-shaped oxidation-induced stacking faults appearing in the crystal plane exceeds 8% of the radius of the grown crystal, and The inner diameter of the oxidation-induced stacking fault is included in the range of 0 to 80% of the grown crystal diameter,
High quality silicon single crystal characterized by low or no in defects. 3. A silicon single crystal grown by the Czochralski method, wherein a wafer processed from an as-grown single crystal is charged into a heat treatment furnace at 650 ° C., and 8 ° C./min or less after the charging. Heat up at 900 ℃ × 20hours and 1000 ℃ × 1
After the heat treatment for 0 hours, when the distribution of oxygen precipitation is observed by X-ray topography, the width of ring-shaped oxidation-induced stacking faults appearing in the crystal plane exceeds 8% of the radius of the grown crystal,
High quality silicon single crystal characterized by no dislocation cluster defects. 4. A silicon single crystal grown by the Czochralski method, wherein a wafer processed from an as-grown single crystal is charged into a heat treatment furnace at 650 ° C., and 8 ° C./min or less after the charging. Heat up at 900 ℃ × 20hours and 1000 ℃ × 1
After the heat treatment for 0 hours, when the distribution of oxygen precipitation is observed by X-ray topography, the width of ring-shaped oxidation-induced stacking faults appearing in the crystal plane exceeds 8% of the radius of the grown crystal,
A high-quality silicon single crystal characterized in that the inner diameter of the ring-shaped oxidation-induced stacking fault is included in the range of 0 to 80% of the diameter of the grown crystal, and the density of Grown-in defects is low or absent.