JPH06295913A - Manufacture of silicon wafer and silicon wafer - Google Patents

Abstract

PURPOSE:To make defectless the active layer of a device and to make it possible to take a sufficient gettering effect by a method wherein a silicon wafer having a specified interstitial oxygen concentration is subjected to specified heat treatment in a hydrogen gas atmosphere and is formed into a wafer having the distribution of the specified density of oxygen deposits. CONSTITUTION:A silicon wafer having an interstitial oxygen concentration Oi less than 1.55X10<18>atoms/cm<3> is subjected to heat treatment in a hydrogen gas atmosphere under conditions that a heat-treating temperature is 1100 to 1300 deg.C, a heat-treating time is one minute to 48 hours and a heating-up speed within a temperature range of 1000 to 1300 deg.C in a heat-treating process is 5 to 10C/min. Thereby, it is made possible to manufacture a wafer, which has a defectless layer containing 10<3> piece/cm<3> or less of BMDs of a size of 20nm or larger extending over at least a depth of 10mum or deeper from the surface of the wafer ans has the density BMD of oxygen deposits, which is set under the conditions of BMD<=1X10<10> piece/cm<3> and BMD>=exp {1.151X10<-17>XOi+1.151} piece/cm<3>, of the internal bulk of the wafer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon wafer for semiconductor devices such as VLSI and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor device for VLSI, a trace amount of metal impurities mixed in a wafer and a device active region of the wafer (a depth of 10 from a wafer surface).
Micro defects existing in the range of about μm may cause deterioration in the characteristics and reliability of the manufactured semiconductor device. Therefore, various measures have been conventionally taken to reduce these metal impurities and minute defects as much as possible.

As a method of reducing metal impurities, there is a backside damage method (BSD method) in which a minute strain is provided on the back surface of a wafer by sandblasting or the like for capturing (gettering) metal impurities. A method of depositing polycrystalline silicon on the back surface of the wafer is also used.

As a measure against the latter, an epitaxial wafer having a vapor-grown single crystal silicon layer having no microdefects in the device active region is used.

Further, an intrinsic gettering method (IG method) has been developed in order to simultaneously take measures against both. The IG method heat-treats a wafer at a high temperature to diffuse outward oxygen on the wafer surface to reduce interstitial oxygen, which is a nucleus of microdefects, and to form a depleted zone (DZ layer) having no microdefects in a device active region. Let it form.
Further, in the deep region (bulk portion) below the DZ layer, the excess interstitial oxygen contained is precipitated by the high temperature heat treatment, and BMD typified by minute SiO ₂ precipitates is generated. These BMDs exert strain on the silicon matrix in the bulk portion to induce secondary dislocations and stacking faults, and getter metal impurities.

In the IG method, a plurality of stages of heat treatment are carried out for the purpose of not being affected by the thermal history of the pulled single crystal silicon ingot and utilizing a wafer having a wider oxygen concentration range. . First, in the pre-heat treatment, heat treatment is performed at a high temperature (up to 1200 ° C.) in an oxygen-containing inert gas atmosphere to diffuse oxygen outward from the wafer surface to remove BMD nuclei originally present from oxygen. Reduce and eliminate. Next, heat treatment at a low temperature (500 to 900 ° C.) in the middle stage in an oxygen atmosphere is performed to generate BMD nuclei in the bulk part. Finally, the BMD nuclei are grown and BMDs are generated and grown by heat treatment in an oxygen atmosphere at a medium temperature (up to 1000 ° C.). Various ideas have been made for the heat treatment in the middle stage, and for example, isothermal annealing, multi-stage annealing from low temperature, ramping annealing from low temperature, etc. are typical.

In the IG method described above, the outward diffusion of oxygen due to the heat treatment in the preceding stage is not sufficient in practice, and minute oxygen precipitates (such as BMD) may remain in the device active region. Further, since a plurality of heat treatment steps are required, practical application has not progressed so much due to workability problems and cost problems.

Recently, instead of the method requiring such multi-step heat treatment, 100% reducing gas or 100% is used.
By performing high-temperature heat treatment in an inert gas atmosphere or a mixed gas atmosphere of a reducing gas and an inert gas, a DZ layer is formed on the wafer surface and a BMD is formed on the bulk portion, and an intrinsic gettering effect (IG effect) is provided. Wafer manufacturing methods are also used. The applicant of the present invention relates to these production methods in JP-A-60-247935 and JP-A-61-19.
3458, JP-A-61-193459, JP-A-61
Nos. 193456, 62-123098, and 2-177541 are filed.

The typical heat treatment in a hydrogen atmosphere of this method is performed by the following temperature process. The temperature raising process for raising the temperature to the heat treatment temperature is from room temperature to 100
About 10 ℃ / min up to 0 ℃, from 1000 ℃ to 12 ℃
Up to 00 ° C, 3 ° C / min or less, heat treatment: about 1200 ° C
For more than 1 hour, the cooling process is from 1200 ℃ to 9 ℃
It is 3 ° C./min or less up to about 00 ° C. A typical temperature process is shown in FIG. In the heat treatment operation of FIG. 1, the temperature rising process is 10 ° C./min from room temperature to 1000 ° C.
3 ° C / min between 00 ° C and 1200 ° C, 1 heat treatment
1 hour at 200 ℃, cooling process from 1200 ℃ to 10 ℃
3 ° C / min up to 00 ° C, 10 ° C / m below 1000 ° C
I'm going in.

In this heat treatment operation, in the temperature raising process in the region of 1000 ° C. or higher, if the temperature raising rate is higher than about 3 ° C./min, slip may occur on the wafer being processed. In addition, the heat treatment furnace that is usually used has not been heated at a high speed because of heat insulation and restrictions of heating elements.

The mechanism of forming the wafer structure by the above heat treatment process can be estimated as follows. Since the temperature rising rate is slow during the temperature raising process, BMD growth occurs in the bulk portion, and at the same time, outward diffusion of oxygen occurs in the surface layer portion, and the oxygen concentration in the surface layer portion decreases. After reaching the heat treatment temperature, outward diffusion of oxygen in the surface layer portion is further performed, interstitial oxygen that becomes BMD nuclei in the surface layer portion is reduced, and disappearance of BMD in the surface layer portion is accelerated. In the bulk portion, oxygen is diffused in the wafer due to the high temperature heat treatment and BMD contraction occurs. However, since the amount of oxygen decrease is small, BMD disappears. Since the temperature rising rate is slow during the temperature lowering process, theoretically, BMD growth also occurs in the wafer surface layer portion, but oxygen in the surface layer portion is reduced by outward diffusion, so that BMD is not formed but becomes a DZ layer. On the other hand, BMD growth / precipitation occurs again in the bulk portion.

FIG. 2 shows a wafer in 100% hydrogen gas, and FIG.
The relation between the initial oxygen concentration of the wafer and the BMD density of the bulk portion of the wafer after the heat treatment when the heat treatment as shown in
Indicate. It is understood from FIG. 2 that the BMD density of the bulk portion after the heat treatment depends on the initial oxygen concentration of the wafer, and the BMD density of the bulk portion increases as the initial oxygen concentration increases.

In recent years, in order to improve the characteristics of a highly integrated memory device or the like, it is required that a silicon wafer as a starting material has a device active layer on the surface that is almost completely defect-free and complicated. It is necessary and important to have a structure capable of gettering metal impurities that are mixed in during the device manufacturing process.

In the former case, that is, in order to form a more complete defect-free layer, it is preferable that the concentration of interstitial oxygen that causes defects is low, but such a wafer is produced by conventional manufacturing methods and conditions. Manufacturing is difficult and there are many problems in terms of productivity and cost. In addition, it is difficult to form a sufficient amount of BMD in the internal bulk portion of such a wafer in the conventional heat treatment process to sufficiently achieve the gettering function.

The present invention has been made in order to solve the above problems. Even in a wafer having a relatively low oxygen concentration range, the device active layer is more defect-free and the BMD is formed in the bulk portion. It is an object of the present invention to provide a method for manufacturing a silicon wafer capable of forming a high density of silicon and exhibiting a sufficient gettering effect, and such a silicon wafer.

[0016]

The first invention of the present application is that the interstitial oxygen concentration [Oi] produced from a single crystal silicon ingot produced by the Czochralski method is 1.55 × 10 ¹⁸ atoms. / Cm ³ of the silicon wafer in a hydrogen gas atmosphere or a mixed gas atmosphere of hydrogen gas and an inert gas, the heat treatment temperature is 1100 ℃ ~ 1
The heat treatment is performed at a temperature of 300 ° C., a heat treatment time of 1 minute to 48 hours, and a temperature rising rate of 5 ° C./min to 10 ° C./min in the temperature range of 1000 ° C. to 1300 ° C. during the heat treatment process. 10 ³ BMDs with a size of 20 nm or more over 10 μm / c
The wafer has a defect-free layer of m ³ or less, and the oxygen precipitate density [BMD] of the bulk portion inside the wafer is [BMD] ≦ 1 × 10 ^10.
Pieces / cm ³ , and [BMD] ≧ exp {1.151 × 1
The gist is a method for manufacturing a silicon wafer, which is characterized in that a wafer having 0 ⁻¹⁷ × [Oi] +1.151} / cm ³ is manufactured. A second invention of the present application is that the interstitial oxygen concentration [Oi] produced from a single crystal silicon ingot produced by the Czochralski method is 1.55 × 1.
A silicon wafer of less than 0 ¹⁸ atoms / cm ^{3 is} treated in a hydrogen gas atmosphere or a mixed gas atmosphere of hydrogen gas and an inert gas at a heat treatment temperature of 1100 ° C. to 1300 ° C. for a heat treatment time of 1 minute to 48 hours. Medium 1000 ℃
From 1 to 1300 ° C in the temperature range of 5 to 1
10 ³ BMDs having a size of 20 nm or more from the surface of the wafer to a depth of 10 μm or more, manufactured by performing a heat treatment under the condition of 0 ° C./min.
^The wafer has a defect-free layer of ³ or less and the density of oxygen precipitates [BMD] in the bulk part inside the wafer is [BMD] ≦ 1 × 10 ¹⁰ pieces / cm ³ , and [BMD] ≧ exp {1.151 × 10
^-17 × [Oi] +1.151} / cm ³ is a silicon wafer.

Further, all oxygen concentrations in this specification are Ol.
d It is a value based on a conversion coefficient according to ASTM.

Generally, the behavior of BMD during heat treatment of a wafer will be described.

According to the classical nucleation theory, BMD grows and contracts by attaching and detaching supersaturated oxygen with oxygen clusters as uniform nuclei.

Whether the BMD existing at a certain time grows or shrinks / extinguishes depends on the size of the BMD at that time and the critical nucleus radius determined by the temperature (and oxygen concentration) at that time. Critical nucleus radius depends on temperature,
The critical nucleus radius increases with increasing temperature. When a wafer is held at a certain temperature, BMDs that have already grown larger than the critical nucleus radius at that temperature continue to grow, and BMDs having a diameter smaller than the critical nucleus radius contract and disappear.

Based on the above findings, the present inventors can realize the present invention by knowing that the BMD can be controlled by applying this to a wafer manufacturing method to manufacture a wafer suitable for manufacturing highly integrated devices. It is a thing.

The present invention is a silicon wafer manufactured from a silicon ingot manufactured by the ordinary Czochralski method, which is a region having a relatively low oxygen content.
It is applied to the heat treatment of wafers of less than 55 × 10 ¹⁸ atoms / cm ³ . A wafer having an oxygen concentration higher than this has a BMD that is not subjected to the heat treatment of the present invention as described above.
The density can be increased.

The heat treatment of the present invention is carried out in a 100% hydrogen gas atmosphere or in a mixed gas atmosphere of hydrogen gas and an inert gas. It is preferable to perform the treatment in a 100% hydrogen gas atmosphere from the viewpoints of forming a defect-free layer, facilitating outward diffusion of oxygen, and preventing surface roughness during heat treatment.

The heat treatment of the present invention is performed at 1100 ° C to 1300 ° C.
Done in. At 1100 ° C or lower, the effect of the present invention is not obtained, and at 1300 ° C or higher, the outward diffusion effect of oxygen is excellent, but there is a problem in safety and reliability of the device.

The heat treatment time of the present invention is 1 minute to 48 hours. If it is less than 1 minute, the effect of the present invention cannot be obtained, and if the heat treatment is performed for more than 48 hours, the effect cannot be expected to be improved.

During the heat treatment process of the present invention, the rate of temperature rise is 5 within the temperature range from 1000 ° C. to the heat treatment temperature.
It is necessary to raise the temperature at 10 ° C / min.

When the rate of temperature rise is less than 5 ° C./min in the region of 1000 ° C. or higher, the above-mentioned increasing rate of the critical nucleus radius does not overtake the BMD growth rate, and B
MD seems to grow. However, in a wafer with a low oxygen content as in the present invention, the amount of attached oxygen itself is small, and the effective heat treatment time including the heating process is long, so the amount of oxygen attached to existing BMD nuclei (probability) ), The amount of oxygen desorbed becomes larger, so that the size of BMD becomes smaller and disappears. Therefore, the density becomes small.

In the region of 1000 ° C. or higher, the temperature rising rate of 5 to 10 ° C./min as defined in the present invention is contrary to the above-mentioned case, and adheres when compared throughout the heat treatment operation. It is considered that the BMD size and density increase because the amount of oxygen becomes larger than the amount of desorbed oxygen.

If the heating rate is higher than 10 ° C./min in the region of 1000 ° C. or higher, the above-mentioned increasing rate of the critical nucleus radius becomes higher than the growth rate of the existing BMD at that temperature, and Since the time of the temperature rising process is shortened, the difference between the critical nucleus radius and the diameter of the existing BMD becomes larger, and the BMD does not grow but tends to shrink.

In this way, the rate of temperature rise is 5 to 10 ° C./min.
Only in such a case, BMD can be formed with high density.

At the heat treatment temperature, outward diffusion of oxygen progresses in the surface region, so that the oxygen concentration around the BMD near the surface decreases and the disappearance progresses to form the DZ layer. The effect of outward diffusion of oxygen is difficult to reach in the bulk portion, and the decrease in oxygen concentration is small. When the temperature is raised at the heating rate of the present invention,
Since the size of BMD is already larger than the critical nucleus radius at the heat treatment temperature, BMD grows.

During the temperature lowering process, the BM is already in the surface layer.
It is considered that BMD does not occur or grow even if the temperature lowering rate is changed because D decreases and the oxygen concentration decreases. BMD has already grown in the bulk portion, and changing the temperature lowering rate has no significant effect. However, the rate of temperature decrease is 2-3 depending on productivity, wafer quality (prevention of slipping and surface roughening), and structural problems of the furnace used.
It is preferably 00 ° C./min.

By performing such heat treatment, a silicon wafer having an initial oxygen concentration of less than 1.55 × 10 ¹⁸ atoms / cm ³ is used, and 10 μm from the wafer surface.
Having a DZ layer having a size of 20 nm or more and a BMD of 10 ³ pieces / cm ³ or less over the above depth, and
BMD density [BMD] ≦ 1 of bulk part in region deeper than layer
× 10 ¹⁰ pieces / cm ³ , and [BMD] ≧ exp {1.1
Wafers of 51 × 10 ⁻¹⁷ × [Oi] +1.151} / cm ³ can be manufactured.

Such a wafer is indicated by the area A + B + C in the graph of FIG.

A wafer having an initial oxygen concentration as described above, having a good DZ layer in the surface layer portion, and having B in the bulk portion.
Conventionally, there is no wafer whose MD density is within the above range,
It is provided for the first time by the present invention.

A more preferable range of BMD density is as follows.
1 × 10 ⁸ pieces / cm ³ ≦ [BMD] ≦ 1 × 10 ¹⁰ pieces / c
m ³ (area B + C in FIG. 2), and further [BMD]
≦ 1 × 10 ¹⁰ pieces / cm ³ and [BMD] ≧ exp
It is {4.605 × 10 ⁻¹⁸ × [Oi] +1.434} pieces / cm ³ (region C in FIG. 2).

A wafer having a BMD density in such a range has a sufficient gettering function, and the surface device active layer is a good defect-free DZ layer.

The BMD in the DZ layer in the surface layer portion is preferably substantially 0. The reason why the BMD in the DZ layer is defined as above is that the detection limit of the BMD size of the current device is 20 nm, and when the BMD density exceeds 10 ³ pieces / cm ³ , it is no longer defective. This is because the characteristics of the manufactured device are adversely affected.

[0039]

EXAMPLES Hereinafter, the wafers used for explaining the examples of the present invention were all silicon wafers cut from a silicon ingot pulled up by the Czochralski method, manufactured by a usual method, and subjected to mirror finishing. These wafers are N type, plane orientation (100),
Specific resistance 1 to 1000 Ω / cm, initial interstitial oxygen concentration [O
i] is 1.45 to 1.74 × 10 ¹⁸ atoms / cm ³
Is.

Example 1 Among the above wafers, [Oi] was 1.51 × 10 ¹⁸ ato
1 ms / cm ³ wafer in 100% hydrogen gas atmosphere
Heat treatment was performed at 200 ° C. for 1 hour. However, 1000 ° C
To 1200 ° C., the heating rate is 6.3 ° C./min,
The temperature lowering rate was 10 ° C./min.

Example 2 Of the above wafers, [Oi] was 1.45 × 10 ¹⁸ ato.
1 ms / cm ³ wafer in 100% hydrogen gas atmosphere
Heat treatment was performed at 200 ° C. for 1 hour. However, 1000 ° C
To 1200 ° C, the heating rate is 8.5 ° C / min,
The temperature lowering rate was 3.8 ° C./min.

Comparative Example 1 Among the above wafers, [Oi] was 1.70 × 10 ¹⁸ ato.
1 ms / cm ³ wafer in 100% hydrogen gas atmosphere
Heat treatment was performed at 200 ° C. for 1 hour. However, 1000 ° C
To 1200 ° C., the temperature rising rate was 30 ° C./min, and the temperature lowering rate was 300 ° C./min.

Comparative Example 2 Among the above wafers, [Oi] was 1.61 × 10 ¹⁸ ato
1 ms / cm ³ wafer in 100% hydrogen gas atmosphere
Heat treatment was performed at 200 ° C. for 1 hour. However, 1000 ° C
To 1200 ° C., the temperature rising rate was 30 ° C./min, and the temperature lowering rate was 300 ° C./min.

Comparative Example 3 Among the above wafers, [Oi] was 1.51 × 10 ¹⁸ ato
1 ms / cm ³ wafer in 100% hydrogen gas atmosphere
Heat treatment was performed at 200 ° C. for 1 hour. However, 1000 ° C
To 1200 ° C., the temperature rising rate was 30 ° C./min, and the temperature lowering rate was 300 ° C./min.

Comparative Example 4 Among the above wafers, [Oi] was 1.70 × 10 ¹⁸ atoms.
1 ms / cm ³ wafer in 100% hydrogen gas atmosphere
Heat treatment was performed at 200 ° C. for 1 hour. However, 1000 ° C
To 1200 ° C., the heating rate was 30 ° C./min, and the cooling rate was 3.8 ° C./min.

Comparative Example 5 Among the above wafers, [Oi] was 1.70 × 10 ¹⁸ ato.
1 ms / cm ³ wafer in 100% hydrogen gas atmosphere
Heat treatment was performed at 200 ° C. for 1 hour. However, 1000 ° C
To 1200 ° C., the rate of temperature increase was 30 ° C./min, and the rate of temperature decrease was 30 ° C./min.

Comparative Example 6 Among the above wafers, [Oi] was 1.61 × 10 ¹⁸ ato
1 ms / cm ³ wafer in 100% hydrogen gas atmosphere
Heat treatment was performed at 200 ° C. for 1 hour. However, 1000 ° C
To 1200 ° C., the heating rate is 6.3 ° C./min,
The temperature lowering rate was 10 ° C./min.

Comparative Example 7 Among the above wafers, [Oi] was 1.70 × 10 ¹⁸ ato.
1 ms / cm ³ wafer in 100% hydrogen gas atmosphere
Heat treatment was performed at 200 ° C. for 1 hour. However, 1000 ° C
To 1200 ° C, the heating rate is 3.8 ° C / min,
The temperature lowering rate was 3.8 ° C./min.

Comparative Example 8 Among the above wafers, [Oi] was 1.70 × 10 ¹⁸ ato.
1 ms / cm ³ wafer in 100% hydrogen gas atmosphere
Heat treatment was performed at 200 ° C. for 1 hour. However, 1000 ° C
To 1200 ° C, the heating rate is 3.8 ° C / min,
The temperature lowering rate was 300 ° C./min.

Comparative Example 9 Among the above wafers, [Oi] was 1.50 × 10 ¹⁸ ato.
1 ms / cm ³ wafer in 100% hydrogen gas atmosphere
Heat treatment was performed at 200 ° C. for 1 hour. However, 1000 ° C
To 1200 ° C. in the range of 2 to 3 ° C./min,
The rate of temperature decrease was 2-3 ° C / min.

Comparative Example 10 Among the above wafers, [Oi] was 1.56 × 10 ¹⁸ ato
1 ms / cm ³ wafer in 100% hydrogen gas atmosphere
Heat treatment was performed at 200 ° C. for 1 hour. However, 1000 ° C
To 1200 ° C. in the range of 2 to 3 ° C./min,
The rate of temperature decrease was 2-3 ° C / min.

Comparative Example 11 Among the above wafers, [Oi] was 1.60 × 10 ¹⁸ ato
1 ms / cm ³ wafer in 100% hydrogen gas atmosphere
Heat treatment was performed at 200 ° C. for 1 hour. However, 1000 ° C
To 1200 ° C. in the range of 2 to 3 ° C./min,
The rate of temperature decrease was 2-3 ° C / min.

Comparative Example 12 Among the above wafers, [Oi] was 1.74 × 10 ¹⁸ ato
1 ms / cm ³ wafer in 100% hydrogen gas atmosphere
Heat treatment was performed at 200 ° C. for 1 hour. However, 1000 ° C
To 1200 ° C. in the range of 2 to 3 ° C./min,
The rate of temperature decrease was 2-3 ° C / min.

The densities of BMDs produced by the infrared tomography method were measured from the cross-section ((110) plane) of the heat-treated wafers of these Examples and Comparative Examples. The minimum detectable BMD size in the infrared tomography method used is 20 nm. This method depends on the measurement area
The detection limit of D density is different. In this measurement, the measurement was performed in a rectangular parallelepiped region having a depth of 185 μm and a surface of 4 × 200 μm. The measurement limit of the BMD density in this case is 6.
It is 8 × 10 ⁶ pieces / cm ³ . Under such conditions, the thickness of the DZ layer having a size of 20 nm or more and having a BMD size of 10 ³ pieces / cm ³ or less, which is defined in the present invention, is the first time in a typical field of view that the BM
D corresponds to the depth from the surface where it is detected.

The measurement results are shown in Tables 1 and 2 together with the heat treatment conditions.
Shown in. FIG. 2 is a graph showing the relationship between the initial oxygen concentration of the wafer and the BMD density.

[0056]

[Table 1]

[Table 2] As is clear from Tables 1 and 2 and FIG. 2, a good DZ layer was formed on the wafer subjected to the heat treatment of the present invention even if the initial oxygen concentration [Oi] was low, and further formed on the bulk portion. BMD having high density can be obtained. That is, it has a defect-free layer having a BMD of 10 ³ pieces / cm ³ or less having a size of 20 nm or more at least 10 μm or more deep from the surface, and the oxygen precipitate density [BMD] of the wafer internal bulk part is [BMD ] ≦ 1 × 10 ¹⁰ pieces / c
m ³ , and [BMD] ≧ exp {1.151 × 10 ⁻¹⁸
Wafers of × [Oi] +1.151} / cm ³ can be manufactured.

On the other hand, as can be understood from the comparative example, the wafers that have been subjected to the heat treatment under the conditions outside the scope of the present invention have more BMDs formed as the initial oxygen concentration is higher. It can be seen that the formed BMD density becomes low. In Comparative Examples 3 and 9, although a defect-free layer is formed, the BMD in the bulk portion inside the wafer has a low density, and there is a possibility that a sufficient gettering function cannot be achieved.

Further, since the wafer of the present invention is constructed as described above, the device active layer is defect-free and the BMD is sufficiently formed in the bulk portion, so that devices having good characteristics can be produced with good yield. It can be manufactured.

In the heat treatment of the present invention, the temperature raising process,
It is preferable to perform the heat treatment and the temperature lowering process in the same gas atmosphere, but the composition of the atmosphere gas may be changed in each case. However, the heat treatment needs to be performed in a hydrogen gas atmosphere or a mixed atmosphere of hydrogen gas and an inert gas.

[0060]

According to the present invention, the BMD density formed even on a wafer having a low initial oxygen concentration can be increased, and as a result, it has a sufficient gettering function, so that a highly integrated device having good characteristics can be manufactured with high yield. be able to.
Further, such a wafer can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a temperature process of conventional heat treatment.

FIG. 2 is a diagram showing the relationship between the initial oxygen concentration of a wafer and the BMD density after heat treatment.

Front page continuation (72) Inventor Kashima Hitotsu, Soya 30 Hadano City, Kanagawa Prefecture, Toshiba Ceramics Co., Ltd.Development Laboratory (72) Inventor Yoshio Kirino 30 Soya, Hadano City, Kanagawa Prefecture, Toshiba Ceramics Co.

Claims (2)

[Claims] 1. A silicon wafer having an interstitial oxygen concentration [Oi] of less than 1.55 × 10 ¹⁸ atoms / cm ³ manufactured from a single crystal silicon ingot manufactured by the Czochralski method is placed in a hydrogen gas atmosphere or In a mixed gas atmosphere of hydrogen gas and inert gas, the heat treatment temperature is set to 11
00 ° C to 1300 ° C, heat treatment time from 1 minute to 48 hours,
During the heat treatment process, the heat treatment is performed at a temperature rising rate of 5 to 10 ° C./min within a temperature range of 1000 ° C. to 1300 ° C., so that at least a depth of 10 from the wafer surface is obtained.
1 BMD with a size of 20 nm or more over μm
Oxygen precipitate density [BMD] in the bulk portion inside the wafer has a defect-free layer of 0 ³ / cm ³ or less, and [BMD] ≦
1 × 10 ¹⁰ pieces / cm ³ , and [BMD] ≧ exp {1.
151 × 10 ^-17 × [Oi] +1.151} pieces / cm ³
A method of manufacturing a silicon wafer, comprising: 2. A silicon wafer having an interstitial oxygen concentration [Oi] of less than 1.55 × 10 ¹⁸ atoms / cm ³ manufactured from a single crystal silicon ingot manufactured by the Czochralski method is used in a hydrogen gas atmosphere or In a mixed gas atmosphere of hydrogen gas and inert gas, the heat treatment temperature is set to 11
00 ° C to 1300 ° C, heat treatment time from 1 minute to 48 hours,
A wafer having a size of 20 nm or more from the surface of the wafer to a depth of 10 μm or more, which is manufactured by performing a heat treatment at a temperature rising rate of 5 to 10 ° C./min in a temperature range of 1000 ° C. to 1300 ° C. during the heat treatment process. A defect-free layer having a BMD of 10 ³ / cm ³ or less,
The oxygen precipitate density [BMD] of the bulk part inside the wafer is
[BMD] ≦ 1 × 10 ¹⁰ pieces / cm ³ , and [BMD] ≧
exp {1.151 × 10 ^-17 × [Oi] +1.15
1} / cm ³ silicon wafer.