JP3412531B2 - Phosphorus-doped silicon single crystal wafer, epitaxial silicon wafer, and methods for producing them - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epitaxial silicon single crystal wafer for producing a semiconductor device having a small amount of heavy metal impurities existing in an epitaxial layer, which is harmful to the reliability of the device, and a phosphorus-doped silicon single crystal wafer used as the substrate thereof. It relates to these manufacturing methods.

[0002]

2. Description of the Related Art Epitaxial silicon single crystal wafers are widely used for individual semiconductors and bipolar I because of their excellent characteristics.
It has been used for a long time as a wafer for producing C and the like. Further, MOS LSIs are also widely used in microprocessor units and flash memory devices because of their excellent soft error and latch-up characteristics. Furthermore, the demand for epitaxial silicon single crystal wafers is ever expanding in order to reduce the reliability defects of DRAM due to so-called grown-in defects that are introduced during the production of silicon single crystals.

However, the presence of heavy metal impurities on the epitaxial silicon single crystal wafer used for such a semiconductor device causes a defective characteristic of the semiconductor device. Especially, the cleanliness required for the most advanced devices has a heavy metal impurity concentration of 1 × 10 ¹⁰ atoms / c.
It is considered to be less than m ² and the heavy metal impurities present on the silicon wafer should be reduced as much as possible.

The gettering technique is becoming more important as one of the techniques for reducing such heavy metal impurities. Conventionally, in manufacturing an epitaxial silicon single crystal wafer for CCD, a phosphorus-doped N-type substrate (hereinafter referred to as a phosphorus-doped silicon single crystal wafer) has been used as a substrate wafer for performing epitaxial growth. However, the phosphorus-doped silicon single crystal wafer has a problem that oxygen precipitation is less likely to occur as compared with a P-type substrate doped with boron (hereinafter referred to as a boron-doped silicon single crystal wafer). Such a lack of gettering ability due to a lack of oxygen precipitation amount of the phosphorus-doped silicon single crystal wafer is a fatal problem in a device such as CCD that is sensitive to crystal defects caused by heavy metal impurities.

Therefore, in order to obtain the same amount of oxygen precipitation as that of a boron-doped silicon single crystal wafer, a phosphorus-doped silicon single crystal wafer requires a gettering heat treatment for a longer period of time than that of a boron-doped silicon single crystal wafer. However, there was a problem that productivity was deteriorated. Specifically, the first stage heat treatment called IG heat treatment at a high temperature of 1100 ° C. or higher and the second stage 60
Precipitation nucleation heat treatment at 0 to 700 ° C, 1st as the third step
The oxygen precipitate formation heat treatment at about 000 ° C. is performed for several hours.

As another method, if the oxygen concentration of the wafer is increased to increase the oxygen precipitation amount of the phosphorus-doped silicon single crystal wafer, the oxygen precipitation is promoted and the time required for such heat treatment can be shortened. In Although,
An excessive amount of oxygen is precipitated on the wafer, which causes problems such as deformation of the wafer and reduction in the strength of the wafer. Further, when an epitaxial layer is formed on the surface of the phosphorus-doped silicon single crystal wafer, there is a problem that harmful defects are generated in the epitaxial layer due to outward diffusion of impurity oxygen, and the epitaxial layer is adversely affected.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is a phosphorus-doped silicon single crystal wafer, in which the oxygen concentration in the substrate is such that the wafer is deformed and the strength of the wafer is reduced. Despite being suppressed to such a degree that does not cause the problem of the above, a silicon wafer for epitaxial growth having high gettering ability that easily precipitates oxygen, and the concentration of heavy metal impurities in the epitaxial layer grown by using the wafer as a substrate wafer. The main purpose is to manufacture and supply extremely low epitaxial silicon single crystal wafers with high productivity.

[0008]

[Means for Solving the Problems] To solve the above problems
The present invention relates to a phosphorus-doped silicon single crystal wafer, wherein the oxygen concentration in the phosphorus-doped silicon single crystal wafer is 18 ppma (JEIDA: Japan Electronic Industry Development Association standard) or less, and an oxygen precipitate after the precipitation heat treatment. Alternatively, the phosphorus-doped silicon single crystal wafer is characterized by having an oxidation-induced stacking fault density of 1 × 10 ⁹ defects / cm ³ or more.

Thus, the phosphorus-doped silicon single crystal
The phosphorus-doped silicon single crystal wafer
Oxygen concentration in the medium and low oxygen concentration of 18ppma or less
Oxygen precipitates or oxidation after precipitation heat treatment despite
Induced stacking fault density is 1 × 10 ⁹ Pieces / cm³ More than oxygen
Phosphorus-doped silicon single crystal wafers that are easy to precipitate are copper
Heat treatment of heavy metal impurities such as nickel and nickel in a short time
Even if there is a high gettering ability, the acid in the wafer
Since the elementary concentration is low, the wafer may be deformed or
It is possible to prevent a lack of degree.

Further, when such a phosphorus-doped silicon single crystal wafer is used as a substrate wafer for manufacturing an epitaxial wafer, harmful defects due to outward diffusion of impurity oxygen are not generated in the epitaxial layer, Moreover, an epitaxial silicon single crystal wafer having a high gettering effect and a very low concentration of heavy metal impurities can be obtained with high productivity by heat treatment for a short time.

Further, the present invention is a phosphorus-doped silicon single crystal wafer, which is obtained by slicing a silicon single crystal rod grown by nitrogen doping by the Czochralski method. a phosphorus-doped silicon single crystal wafer, characterized in that those were.

As described above, the phosphorus-doped silicon single crystal wafer was obtained by slicing a silicon single crystal rod grown by nitrogen doping by the Czochralski method. If it is, the presence of nitrogen promotes the precipitation of oxygen in the bulk part of the wafer, so that the oxygen concentration in the substrate is at a relatively low concentration that does not cause problems such as deformation of the wafer or reduction in the strength of the wafer. Even if there is, a short time heat treatment has a high gettering effect.

Further, when such a phosphorus-doped silicon single crystal wafer is used as a substrate wafer for producing an epitaxial wafer, an epitaxial silicon having a high gettering effect in a short time heat treatment and an extremely low heavy metal impurity concentration is obtained. A single crystal wafer can be obtained with high productivity.

In this case , the nitrogen concentration of the phosphorus-doped silicon single crystal wafer is 1 × 10 ^{10 to} 5 × 10 ¹⁵ atoms /
It is preferably cm ³ . This is preferable to be 1 × 10 ¹⁰ atoms / cm ³ or more in order to suppress the formation of so-called grown-in defects in the phosphorus-doped silicon wafer by nitrogen and to sufficiently promote oxygen precipitation. In order not to hinder the crystallization of the silicon single crystal in the Larsky method, 5 × 10
^This is because it is preferable to set it to ¹⁵ atoms / cm ³ or less.

Further, the oxygen concentration of the phosphorus-doped silicon single crystal wafer, may be of the following 18 PPMA. When the medium / low oxygen content is 18 ppma or less, the risk of wafer deformation and wafer strength reduction is further reduced, and formation of crystal defects in the phosphorus-doped silicon single crystal wafer is suppressed. Therefore, formation of oxygen precipitates on the surface layer of the wafer can be prevented. Therefore, when the epitaxial layer is formed on the wafer surface, the crystallinity of the epitaxial layer is not adversely affected. On the other hand, since oxygen precipitation is promoted by the presence of nitrogen in the bulk portion, a gettering effect can be sufficiently exerted even with such low oxygen.

Further , it is preferable that the phosphorus-doped silicon single crystal wafer has been subjected to a heat treatment at a temperature of 900 ° C. to a melting point of silicon or lower. Thus, if the phosphorus-doped silicon single crystal wafer is heat-treated at a temperature of 900 ° C. to the melting point of silicon or lower, nitrogen and oxygen on the surface of the phosphorus-doped silicon single crystal wafer are diffused outward, The crystal defects in the wafer surface layer are extremely small. Further, when a high temperature heat treatment such as formation of an epitaxial layer is performed thereafter, the precipitation nuclei do not melt and precipitation does not occur, and the wafer has a sufficient gettering effect.

The present invention is an epitaxial silicon single crystal wafer, wherein the epitaxial layer is formed on the surface layer of the phosphorus-doped silicon single crystal wafer described in any one of the above. It is a silicon single crystal wafer.

As described above, in the epitaxial silicon single crystal wafer in which the epitaxial layer is formed on the surface layer portion of the phosphorus-doped silicon single crystal wafer of the present invention, the oxygen concentration in the substrate is such that the wafer is deformed and the strength of the wafer is reduced. Despite being suppressed to a level that does not cause a problem, heavy metal such as copper and nickel has a high gettering effect by a short time heat treatment, and the concentration of heavy metal impurities is extremely low and high productivity epitaxial silicon It becomes a crystal wafer.

Further, according to the present invention , in a method for producing a phosphorus-doped silicon single crystal wafer, a silicon single crystal rod doped with phosphorus by the Czochralski method and grown with nitrogen is grown, and the silicon single crystal rod is sliced. Is a silicon single crystal wafer, which is characterized in that it is a phosphorus-doped silicon single crystal wafer.

As described above, in the method for producing a phosphorus-doped silicon single crystal wafer, a silicon single crystal rod doped with phosphorus and grown with nitrogen is grown by the Czochralski method, and the silicon single crystal rod is sliced to obtain silicon. When a phosphorus-doped silicon single crystal wafer is manufactured by processing it into a single crystal wafer, oxygen precipitation is promoted by the presence of nitrogen in the bulk part of the wafer, so it is a phosphorus-doped silicon single crystal wafer in which oxygen precipitation is relatively unlikely to occur. Therefore, even if the oxygen concentration in the substrate is a concentration that does not cause problems such as wafer deformation and wafer strength reduction, a short time heat treatment produces a phosphorus-doped silicon single crystal wafer having a high gettering effect. can do.

Further, when the phosphorus-doped silicon single crystal wafer manufactured by such a method is used as a substrate wafer for manufacturing an epitaxial wafer, it has a high gettering effect in a short time heat treatment and has a heavy metal impurity concentration. It is possible to obtain an epitaxial silicon single crystal wafer having a high-quality epitaxial layer with a very low yield with high productivity.

In this case , when growing a silicon single crystal rod doped with nitrogen by the Czochralski method, the concentration of nitrogen doped in the single crystal rod is 1 × 10 ^{10 to} 5 × 10 5.
¹⁵ atoms / cm ³ is preferable, the oxygen concentration contained in the single crystal rod can be 18 ppma or less, and the phosphorus-doped silicon single crystal wafer has a temperature of 900 ° C. to a melting point of silicon or less. It is preferable to apply heat treatment at a temperature.

When the phosphorus-doped silicon single crystal wafer is manufactured in this manner, the phosphorus-doped silicon single crystal wafer having a higher gettering ability, less surface defects and suitable for epitaxial growth with various characteristics is suitable for the substrate wafer. Can be manufactured.

The present invention further provides a method for producing an epitaxial silicon single crystal wafer, which is a method for producing a phosphorus-doped silicon single crystal wafer according to any one of the above, to produce a phosphorus-doped silicon single crystal wafer. A method for producing an epitaxial silicon single crystal wafer, which comprises forming an epitaxial layer on a surface layer portion of the crystal wafer.

As described above, in the method for producing the epitaxial silicon single crystal wafer, the phosphorus-doped silicon single crystal wafer is produced by the above-mentioned method for producing the phosphorus-doped silicon single crystal wafer, and the phosphorus-doped silicon single crystal wafer is formed on the surface layer portion thereof. By forming an epitaxial layer,
Even if the oxygen concentration in the substrate is suppressed to a level that does not cause problems such as wafer deformation and wafer strength reduction, heavy metals such as copper and nickel have a high gettering effect in a short time heat treatment. An epitaxial silicon single crystal wafer having an extremely low impurity concentration can be manufactured with high productivity.

The present invention will be described in more detail below.
The present invention is not limited to these. The present invention is
A phosphorus-doped silicon single crystal wafer, a phosphorus-doped silicon single crystal wafer having a medium / low oxygen concentration and a large oxygen precipitate or oxidation-induced stacking fault density, particularly by a technique of doping nitrogen during crystal growth, By providing a substrate wafer for producing an epitaxial silicon single crystal wafer, it has a high gettering effect in a short time heat treatment without generating harmful defects due to outward diffusion of impurity oxygen in the epitaxial layer, The inventors have found that an epitaxial single crystal wafer having an extremely low impurity concentration can be manufactured with high productivity, and have scrutinized various conditions to complete the present invention.

That is, it has been pointed out that when nitrogen is doped into a silicon single crystal, the aggregation of oxygen atoms in silicon is promoted and the concentration of oxygen precipitates is increased (T.Abe.
and H.Takeno, Mat.Res.Soc.Symp.Proc.Vol.262,3,1992
). This effect is considered to be because the aggregation process of oxygen atoms shifts from homogeneous nucleation to heterogeneous nucleation with impurity nitrogen as nuclei.

Therefore, if nitrogen is doped when growing a silicon single crystal by the Czochralski method, a silicon single crystal having a high oxygen precipitate concentration and a silicon single crystal wafer obtained by processing the silicon single crystal can be obtained. Then, by growing an epitaxial layer using this silicon single crystal wafer as a substrate, it is possible to obtain a high oxygen precipitate density even with a phosphorus-doped silicon single crystal wafer that is originally hard to precipitate oxygen, and as a result, the density of heavy metal impurities is extremely low. An epitaxial layer can be grown. Furthermore, since the oxygen concentration in the wafer can be lowered, problems such as wafer deformation and wafer strength reduction do not occur, and the epitaxial layer is not adversely affected by impurity oxygen, and the so-called Grown-i
Since formation of n-defects can also be suppressed, an epitaxial layer having extremely excellent crystallinity can be obtained.

The phosphorus-doped silicon single crystal wafer manufactured by doping nitrogen during the growth of the silicon single crystal as described above is a phosphorus-doped silicon single crystal wafer which is originally said to be resistant to oxygen precipitation and has a low gettering effect. Even if there is a high gettering effect, it is possible to form a high-quality epitaxial layer, and long-term gettering heat treatment is not required. It can also be expected to improve productivity and cost.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, for growing a silicon single crystal rod doped with phosphorus and nitrogen with the Czochralski method, for example, Japanese Patent Laid-Open No. Sho 60-1985 is used.
A publicly known method such as the one described in No. 251190 may be used.

That is, in the Czochralski method, a seed crystal is brought into contact with a melt of a polycrystalline silicon raw material housed in a quartz crucible, and the seed crystal is slowly pulled up while rotating to grow a silicon single crystal rod having a desired diameter. The method is to put phosphorus-doped polycrystalline silicon raw material in the quartz crucible in advance, and put the nitride in the quartz crucible, or put the nitride in the silicon melt, By setting the atmosphere gas to be an atmosphere containing nitrogen or the like, nitrogen can be doped into the pulled crystal. At this time, the amount of nitrogen doped in the crystal can be controlled by adjusting the amount of nitride, the concentration of nitrogen gas, the introduction time, or the like.

As described above, when growing a single crystal ingot by the Czochralski method, by doping with nitrogen, the grown-in defects introduced can be reduced and the aggregation of oxygen atoms in silicon can be reduced. Can be promoted and the concentration of oxygen precipitates can be increased. This method does not need to slow down the pulling speed conventionally performed to reduce the grown-in defects,
Since the method can be easily performed by using the conventional manufacturing apparatus, it is possible to manufacture a silicon single crystal with high productivity without adding a new manufacturing apparatus or the like.

Further, conventionally, in the case of a phosphorus-doped silicon single crystal wafer, oxygen precipitation is less likely to occur as compared with a boron-doped silicon single crystal wafer, and the gettering ability necessary for device manufacturing cannot be obtained. On the other hand, in order to solve this problem, increasing the oxygen precipitation heat treatment time decreases the productivity of the wafer, and increasing the oxygen concentration in the wafer causes the deformation of the wafer or the decrease in the wafer strength, and also the epitaxial growth on the wafer surface. When the layer is formed, defects are generated due to outward diffusion of impurity oxygen into the epitaxial layer, which rather deteriorates the characteristics. However, by doping nitrogen into the silicon single crystal as in the present invention, the gettering ability required for device manufacturing can be obtained without prolonging the heat treatment time or increasing the oxygen concentration.

When nitrogen is doped into a silicon single crystal,
The reason why the aggregation of oxygen atoms in silicon is promoted and the concentration of oxygen precipitates becomes high is that the aggregation process of oxygen atoms shifts from homogeneous nucleation to heterogeneous nucleation with impurity nitrogen as a nucleus as described above. It is believed that there is. Therefore, the concentration of the doping nitrogen causes sufficient heterogeneous nucleation, 1
It is preferable that the concentration is × 10 ¹⁰ atoms / cm ³ or more. Thereby, the concentration of oxygen precipitates can be made sufficiently high. On the other hand, the nitrogen concentration is the solid solution limit in the silicon single crystal.
If it exceeds × 10 ¹⁵ atoms / cm ³ , the single crystallization itself of the silicon single crystal may be hindered, so it is preferable not to exceed this concentration.

Further, in the present invention, since the concentration of oxygen precipitates is high even at a low oxygen concentration, when growing a nitrogen-doped silicon single crystal ingot by the Czochralski method, the oxygen concentration contained in the single crystal ingot is controlled. It is possible to attain a medium or low oxygen concentration of 18 ppma or less. When the oxygen concentration in the silicon single crystal is 18 ppma or less, defects such as oxygen precipitates that deteriorate the crystallinity of the epitaxial layer can be almost completely prevented from being formed on the surface of the silicon single crystal wafer. It is possible to prevent the crystallinity of the epitaxial layer grown on the surface of the crystal wafer from being adversely affected. On the other hand, in the bulk portion, the precipitation of oxygen is promoted by the presence of nitrogen, so that the gettering effect can be sufficiently exhibited even with medium and low oxygen.

When growing a silicon single crystal ingot, a method for reducing the contained oxygen concentration to the above range may be a conventionally used method. For example, the oxygen concentration range can be easily adjusted by means of reducing the number of rotations of the crucible, increasing the flow rate of introduced gas, lowering the atmospheric pressure, adjusting the temperature distribution and convection of the silicon melt.

Thus, in the Czochralski method, phosphorus is doped and nitrogen of a desired concentration is doped,
A silicon single crystal ingot having few crystal defects on the surface and containing oxygen at a desired concentration can be obtained. According to a usual method, after slicing with a cutting device such as an inner peripheral blade slicer or a wire saw, it is processed into a silicon single crystal wafer through steps such as chamfering, lapping, etching and polishing. Of course, these steps are only listed as examples, and there may be various steps such as cleaning and heat treatment in addition to these, and the steps are appropriately changed and used depending on the purpose such as changing the order of the steps or omitting some.

Next, before the epitaxial growth, the obtained phosphorus-doped silicon single crystal wafer was heated to 900 ° C.
It is preferable to apply heat treatment at a temperature equal to or lower than the melting point of silicon. By performing this heat treatment before forming the epitaxial layer, nitrogen on the surface of the silicon single crystal wafer can be diffused outward.

The outward diffusion of nitrogen on the surface of a silicon single crystal wafer is caused by the oxygen precipitation promoting effect of nitrogen, whereby oxygen is precipitated in the surface layer of the silicon single crystal wafer, and defects are formed based on this, which adversely affects the epitaxial layer. This is to prevent the occurrence of

In this case, the diffusion rate of nitrogen in silicon is remarkably faster than that of oxygen. Therefore, by applying heat treatment, nitrogen on the surface can be surely diffused outward.
As a specific heat treatment condition, it is preferable to perform the heat treatment in a temperature range of 900 ° C. to the melting point of silicon, more preferably 1100 ° C. to 1200 ° C. By performing the heat treatment in such a temperature range, nitrogen in the phosphorus-doped silicon single crystal wafer surface layer can be sufficiently diffused outward, and
At the same time, oxygen can also be diffused outward, so that the generation of defects due to oxygen precipitates in the surface layer can be almost completely prevented, and the crystallinity of the epitaxial layer can be prevented from being adversely affected.

If the above heat treatment is not performed before the epitaxial growth and the high temperature heat treatment for the direct epitaxial growth is applied, the oxygen precipitation nuclei are dissolved, and the precipitation is not sufficiently caused by the subsequent heat treatment. There is a concern that the ring effect cannot be obtained, but if the heat treatment as described above is performed before the high temperature heat treatment for epitaxial growth, a sufficient gettering effect can be obtained during the formation of the epitaxial layer and the heavy metal impurity concentration An extremely low epitaxial silicon single crystal wafer can be obtained. Furthermore, as a side effect, oxygen precipitates in the bulk of the wafer further grow and stacking faults (BS
In some cases, a stronger gettering effect may be exhibited by inducing F: Bulk Stacking Faults.

[0042]

EXAMPLES Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. (Example) By a CZ method, a quartz crucible having a diameter of 18 inches was charged with a raw material polycrystalline silicon to which a predetermined concentration of phosphorus was added, and a silicon wafer having a silicon nitride film was charged together with the raw material polycrystalline silicon. Then, the single crystal ingot having a diameter of 6 inches, N type, and orientation <100> was pulled at a normal pulling rate of 1.0 mm / min. When pulling the crystal, the crucible rotation was controlled so that the oxygen concentration in the single crystal was 18 ppma (JEI
DA).

The nitrogen concentration in the tail of this single crystal rod was measured by FT-I.
When measured by R, it was 5.0 × 10 ¹⁴ atoms / cm ³ . Further, when the oxygen concentration of the single crystal rod was measured by FT-IR, it was confirmed that the oxygen concentration was 18 ppma.

From the single crystal rod obtained here, a wafer was cut out using a wire saw, chamfered, lapping, etched, and mirror-polished to prepare four silicon single crystal mirror-finished wafers having a diameter of 6 inches. When the resistivity of these four silicon single crystal wafers was measured, all four wafers had a resistivity of about 5 to 10 Ω · cm, which was within the range expected from the doping amount of phosphorus added.

Before forming an epitaxial layer on the surface of two of these four silicon single crystal wafers, 110
Nitrogen on the surface of the wafer was diffused outward by applying heat treatment at 0 ° C. for 30 minutes.

Of these two silicon single crystal wafers, one is at 1170 ° C. and the other is 113
A silicon epitaxial layer having a thickness of 20 μm was grown at a temperature of 0 ° C. In the epitaxial growth furnace, a cylinder type bell jar was provided with a susceptor for mounting a substrate wafer, and the heating system was a radiant heating system.
By introducing SiHCl ₃ + H ₂ into this, silicon was epitaxially grown on the phosphorus-doped silicon single crystal wafer. In order to measure the gettering ability of the thus obtained epitaxial wafer, a heat treatment was performed at 800 ° C. for 4 hours in an N ₂ gas atmosphere, and then a heat treatment was performed at 1000 ° C. for 16 hours in an O ₂ gas atmosphere to precipitate oxygen precipitates. . After that, the gettering effect of these epitaxial single crystal wafers was evaluated by the concentration of oxygen precipitates in the bulk of the silicon wafer.

The measurement of this oxygen precipitate concentration is carried out by OPP (Opti
cal Precipitate Profiler) method. This OPP method is an application of a normalski type differential interference microscope, in which a laser beam emitted from a light source is first separated into two 90 ° linearly polarized beams having mutually different phases by a polarizing prism to obtain a wafer mirror surface. It is incident from the side. At this time 1
Phase shift occurs when one beam crosses the defect and the other
A phase difference between the two beams occurs. Defects are detected by detecting this phase difference with a polarization analyzer after passing through the back surface of the wafer.

The results of this measurement are shown in FIG. Figure 1
The plot on the right side of the figure shows that the nitrogen doping amount is 5.0 × 10 5.
The oxygen precipitate defect density of a wafer of ¹⁴ atoms / cm ³ is shown,
The circular plot shows the oxygen precipitate defect density when the epitaxial growth was performed at 1170 ° C., and the triangular plot shows the oxygen precipitate defect density when the epitaxial growth was performed at 1130 ° C.

From FIG. 1, it can be seen that the wafer epitaxially grown on the surface of the phosphorus-doped silicon single crystal wafer doped with nitrogen has an oxygen concentration of 18 ppma, which is a medium value. Similarly, it shows a high oxygen precipitate density of 1 × 10 ⁹ pieces / cm ³ or more, which shows that it has a high gettering effect. Comparing the presence or absence of the heat treatment before epitaxial growth, it can be seen that the gettering effect is greater with the heat treatment. Since the oxygen concentration was low, the crystallinity of the epitaxial layer was very good.
Further, the precipitation heat treatment time before the epitaxial growth in this example is either no heat treatment at all or an extremely short time as compared with the conventional IG heat treatment, and improvement in productivity can be expected.

(Comparative Example) 6 inch in diameter, N type, orientation <100, in the same manner as in Example except that nitrogen was not doped.
>, A phosphorus-doped silicon single crystal ingot having an oxygen concentration of 18 ppma was pulled up. Then, from this single crystal ingot, four silicon single crystal mirror-polished wafers having a diameter of 6 inches were prepared in the same manner as in the example. The resistivity of each of the four silicon single crystal wafers was about 5 to 10 Ω · cm, as in the example.

Two of these four wafers were further subjected to IG heat treatment to promote oxygen precipitation.
That is, first, a first-stage heat treatment at 1100 ° C. for 30 minutes was applied, then a precipitation nucleation heat treatment at 650 ° C. was performed for 4 hours, and an oxygen precipitate formation heat treatment at 1000 ° C. was further added for 16 hours. Of these two silicon single crystal wafers, 1
One of them was grown at 1170 ° C. and the other was grown at a temperature of 1130 ° C. to grow a silicon epitaxial layer having a thickness of 20 μm.
Then, an oxygen precipitate is deposited on the obtained epitaxial wafer by heat treatment in the same manner as in the example, and OP
The gettering effect of these epitaxial silicon single crystal wafers was evaluated by the P method based on the concentration of oxygen precipitates in the bulk of the silicon wafer.

The results of this measurement are also shown in FIG. Here, the plot shown on the left side of FIG. 1 shows the oxygen precipitate defect density of the wafer not doped with nitrogen, and the circular plot shows the case where epitaxial growth was performed at 1170 ° C.
The triangular plot shows the oxygen precipitate defect density when epitaxial growth was performed at 1130 ° C.

From FIG. 1, the wafer obtained by epitaxial growth on the surface of a phosphorus-doped silicon single crystal wafer not doped with nitrogen was IG before the epitaxial growth.
It can be seen that the oxygen precipitate density is low and the gettering effect is low regardless of the temperature at which the epitaxial growth is performed, because the oxygen concentration is 18 ppma, which is a medium value without heat treatment. In addition, I
Even when the G heat treatment is performed, the same precipitate density as that obtained when nitrogen is doped and the pre-epitaxial growth heat treatment is not performed can be obtained.

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

For example, when growing a nitrogen-doped silicon single crystal ingot by the Czochralski method in the present invention, it does not matter whether a magnetic field is applied to the melt or not. The Larsky method also includes a so-called MCZ method for applying a magnetic field.

The epitaxial growth is not limited to the epitaxial growth by the CVD method.
The present invention can also be applied to the case where an epitaxial silicon single crystal substrate is manufactured by performing epitaxial growth by the MBE method.

Further, in the above-described embodiment, the description has been centered on the case where even a phosphorus-doped silicon single crystal wafer having a medium / low oxygen concentration and having a high gettering effect can be obtained by doping nitrogen in particular. However, the present invention is not limited to this, and a phosphorus-doped silicon single crystal wafer having an oxygen concentration in the silicon single crystal wafer of 18 ppma or lower at a medium or low concentration, and after precipitation heat treatment As long as the oxygen precipitates or the oxidation-induced stacking fault density of 1 are as high as 1 × 10 ⁹ defects / cm ³ or more, they are included in the scope of the present invention.

The density of oxygen precipitates or oxidation-induced stacking faults of 1 × 10 ⁹ pieces / cm ³ or more in the present invention means that the heat treatment for epitaxial growth can be performed even after the heat treatment for precipitation is applied to the silicon wafer. Also in the case where the precipitation heat treatment is added after the addition, the oxygen precipitates or the oxidation-induced stacking fault density as described above are also included in the scope of the present invention.

[0059]

As described above, according to the present invention, by using a nitrogen-doped silicon wafer as a substrate of an epitaxial silicon single crystal wafer, even if phosphorus-doped silicon single crystal wafers, which are originally difficult to precipitate oxygen, do not undergo oxygen precipitation. It has high gettering ability, and when epitaxial growth is performed on the wafer surface, high-quality epitaxial silicon single crystal wafer with low defect density and heavy metal impurity concentration in the epitaxial layer can be produced easily and easily. can do.

[Brief description of drawings]

FIG. 1 is a result chart showing measurement results of oxygen precipitate defect densities of wafers by an OPP method in Examples and Comparative Examples.

Continuation of the front page (56) References JP-A-10-303208 (JP, A) JP-A-7-41391 (JP, A) JP-A-10-229093 (JP, A) JP-A-60-251190 (JP , A) Tokuyohei 7-508613 (JP, A) Hideki TSUYA, et. a. , Behaviours of Thermally Induced Microdefects in Healy Doped Silicon Wafers, Jan. J. App l. Phys, January 1983, VoL. 22, No. 1, pp. L16-L18 J. S. Yang, et. al. , I NTRINSIC GETTERING IN NITROGEN-DOPED CZ-SI, 1991, Vol. 19 & 20, pp. 65-68 (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/26-21/268 H01L 21/322-21/326 C30B 1/00-35/00

Claims (7)

(57) [Claims] 1. A table of phosphorus-doped silicon single crystal wafers.
Epitaxy with an epitaxial layer formed on the layer
A Le silicon single crystal wafer, wherein the phosphorus-doped silicon single crystal wafer, which nitrogen is obtained by slicing a dope to a grown silicon single crystal rod by the Czochralski method, the phosphorus-doped silicon An epitaxial silicon single crystal wafer, wherein the oxygen concentration of the single crystal wafer is 18 ppma or less. Wherein said phosphorus nitrogen concentration doped silicon single crystal wafer ^{is, 1 × 10 10 ~5 × 10} 15 epitaxially <br/> silicon according to claim 1, characterized in that the atoms / cm ³ Single crystal wafer. 3. The phosphorus-doped silicon single crystal wafer is heat-treated at a temperature of 900 ° C. to a temperature equal to or lower than a melting point of silicon before the epitaxial layer is formed. e as set forth in claim 2
Pitaxial silicon single crystal wafer. 4. The oxygen precipitate or the oxidation-induced stacking fault density after the precipitation heat treatment is 1 × 10 ⁹ defects / cm ³ or more, according to any one of claims 1 to 3. Epitaxial silicon single crystal wafer. 5. A method of manufacturing an epitaxial silicon single crystal wafer, wherein a silicon single crystal rod doped with phosphorus by the Czochralski method and nitrogen doped is grown with an oxygen concentration contained in the single crystal rod of 18 ppma or less. Then, the silicon single crystal rod is sliced and processed into a silicon single crystal wafer.
A method for manufacturing an epitaxial silicon single crystal wafer, which comprises forming an epitaxial layer on a surface layer portion of the single crystal wafer. 6. When growing a silicon single crystal ingot doped with nitrogen by the Czochralski method, the concentration of nitrogen doped in the single crystal ingot is set to 1 × 10 ^{10 to} 5 × 10 ¹⁵ at.
6. The epi according to claim 5 , wherein oms / cm ³ is set.
Method for manufacturing a taxi silicon single crystal wafer. 7. The phosphorus-doped silicon single crystal wafer is subjected to heat treatment at a temperature of 900 ° C. to a melting point of silicon or lower before the epitaxial layer is formed , according to claim 5 or 6 . Method for manufacturing epitaxial silicon single crystal wafer.