JP4710603B2 - Annealed wafer and its manufacturing method - Google Patents

Description

  The present invention relates to a high-quality silicon wafer, an epitaxial wafer, an annealed wafer, and a manufacturing method thereof, which effectively use the influence of carbon and nitrogen doped on a CZ silicon single crystal.

  With the high integration and miniaturization of device processes, there is a strong demand for reduction of grown-in defects in a silicon wafer as a base. Therefore, a new silicon is added to the whole surface N (neutral) -region wafer, which is developed by improving the growth conditions of the CZ silicon single crystal manufactured by the Czochralski (CZ) method, or a normal silicon wafer. Several types of wafers with few grown-in defects have been developed, such as a grown silicon epitaxial wafer (hereinafter sometimes referred to as an epitaxial wafer or an epi wafer) and an annealed wafer subjected to high-temperature heat treatment in a hydrogen or argon atmosphere.

Here, a method for manufacturing the entire N-region wafer will be described.
First, a vacancy-type point defect called vacancy (hereinafter may be abbreviated as V) incorporated into a silicon single crystal, and interstitial-silicon (hereinafter abbreviated as I). What is generally known about the factor that determines the concentration of each interstitial-type silicon point defect, called, will be described.

  In a silicon single crystal, the V-region is a vacancy, that is, a region having many recesses and holes generated due to a shortage of silicon atoms, and the I-region is generated by the presence of extra silicon atoms. A neutral region (Neutral region, hereinafter referred to as an N-region) that has a shortage of atoms and no (or few) atoms between the V-region and the I-region. May be abbreviated). The grown-in defects (FPD, LSTD, COP, etc.) are generated only when V and I are in a supersaturated state. It has been found that it does not exist.

  It is known that the concentration of these two point defects is determined by the relationship between the crystal pulling rate (growth rate) V in the CZ method and the temperature gradient G near the solid-liquid interface in the crystal. In addition, in the N-region between the V-region and the I-region, it has been confirmed that there is a ring-shaped defect called OSF (Oxidation Induced Stacking Fault).

  When these defects due to crystal growth are classified, for example, when the growth rate is relatively high, such as about 0.6 mm / min or more, FPD, LSTD, and COP that are attributed to voids in which vacancy-type point defects are gathered. Groin-in defects such as these are present at high density throughout the crystal diameter direction, and a region where these defects exist is called a V-rich region. When the growth rate is 0.6 mm / min or less, the OSF ring is generated from the periphery of the crystal as the growth rate is reduced, and interstitial silicon type point defects are gathered outside the ring. L / D (Large Dislocation: Abbreviation of interstitial dislocation loop, LSEPD, LFPD, etc.) defects that are thought to be caused by loops exist at low density, and the region where these defects exist is called an I-rich region Yes. Furthermore, when the growth rate is lowered to about 0.4 mm / min or less, the OSF ring aggregates and disappears at the center of the wafer, and the entire surface becomes an I-rich region.

  Further, in the middle of the V-rich region and the I-rich region, outside of the OSF ring, there is no void-induced FPD, LSTD, COP, dislocation loop-induced LSEPD, LFPD, or even an N-region of OSF. Existence has been discovered. This region is outside the OSF ring, and when oxygen precipitation heat treatment is performed and the contrast of the precipitation is confirmed by X-ray observation or the like, there is almost no oxygen precipitation and is so rich that LSEPD and LFPD are formed. It is not the I-rich region side. Further, the existence of an N-region in which neither a defect caused by a void nor a defect caused by a dislocation loop exists and no OSF exists is confirmed inside the OSF ring.

  In the normal method, these N-regions exist only at an angle with respect to the growth axis direction when the growth rate is lowered.

  With respect to this N-region, in the Boronkov theory (see, for example, Non-Patent Document 1), the parameter V / G, which is the ratio of the pulling speed V and the temperature gradient G in the crystal solid-liquid interface axial direction, determines the total concentration of point defects. Then she chants. Considering this, since the pulling speed should be constant in the plane, since G has a distribution in the plane, for example, at a certain pulling speed, the center is the V-rich region and the N-region is sandwiched around it. Only crystals that would be in the I-rich region were obtained.

  Therefore, recently, when the distribution of G in the plane has been improved, the N-region that has existed only at an oblique angle, for example, when the pull-up speed V is gradually lowered, the N-region is laterally moved at a certain pull-up speed. Crystals spread over the entire surface can be manufactured. Further, in order to expand the crystal of the entire N-region in the length direction, it can be achieved to some extent if the pulling rate is maintained while the N-region is expanded laterally. Also, considering that G changes as the crystal grows, if it is corrected and the pulling rate is adjusted so that V / G is constant, the entire surface N− The area crystal can be enlarged.

  Recently, a wafer having a strong gettering capability is also required to remove the influence of impurities in the device process. For this, a nitrogen-doped N-region wafer that is pulled up in the N-region while doping silicon during the pulling of the silicon single crystal by the CZ method in order to add heat treatment or to utilize the oxygen precipitation promoting effect of nitrogen, By producing a nitrogen-doped epitaxial wafer epitaxially grown on a nitrogen-doped wafer or a nitrogen-doped annealed wafer obtained by annealing a nitrogen-doped wafer, a BMD (Bulk Micro Defect) in the bulk is formed by an internal micro-deposition due to oxygen precipitates. Wafers and the like having an increased IG (Internal Gettering) effect have been developed.

  In recent years, the demand for the gettering ability of manufacturers producing devices is very strong, and the gettering ability as an added value of the wafer used has become indispensable. However, conventional N-region wafers, epi wafers, and annealed wafers do not have sufficient BMD density due to oxygen precipitation during the device process.

  Therefore, a wafer doped with nitrogen utilizing the effect of promoting oxygen precipitation of nitrogen was developed. By doping nitrogen, the range of pulling speed at which the N-region can be obtained can be expanded so that stable crystal growth can be expected. However, in order to fabricate an N-region wafer, the pulling speed is about 0.5 mm / min. However, there was no change in the amount that had to be reduced, leading to a decrease in productivity and an increase in cost.

  Further, when the concentration of nitrogen to be doped is increased, the OSF region may be enlarged, or secondary defects such as dislocation clusters (hereinafter, sometimes referred to as LEP (Large Etch Pit)) may occur in the region. Since it is a source of defects in the epitaxial layer, it is currently impossible to employ a very high nitrogen concentration. Therefore, although the BMD density obtained by the nitrogen doped wafer is larger than that of the nitrogen non-doped wafer, it is suppressed to a moderate density. Here, the secondary defects referred to in the present invention are defects generated in the OSF region that is enlarged due to the high concentration of nitrogen doping, and typical examples thereof include dislocation clusters (LEP) and dislocation loops. Can be mentioned.

  Further, nitrogen is known to form oxygen precipitation nuclei that are stable at high temperatures (see, for example, Non-Patent Document 2), but it is not involved in the formation of precipitation nuclei from low temperatures. There is a problem that the formation of precipitation nuclei cannot be expected.

V. V. Voronkov; Journal of Crystal Growth, 59 (1982) 625-643. Proceedings of the 46th Joint Lecture on Applied Physics in Spring 1999 No. 1, p. 461, 29a-ZB-5, Aihara et al.

  The present invention was made in order to solve such problems, and developed a silicon single crystal growth technique that allows a silicon single crystal having a high IG capability to be grown at a high speed while having few grow-in defects. The main object is to provide a silicon wafer having high IG capability over the entire crystal N-region, or an epitaxial wafer and annealed wafer having excellent crystallinity and IG capability.

  The present invention for solving the above-mentioned problems is that when a silicon single crystal is grown by the Czochralski method, carbon is doped and V / G (V: crystal pulling speed, G: crystal axis direction at the crystal solid-liquid interface) The silicon single crystal manufacturing method is characterized in that the crystal is pulled while controlling the temperature gradient so that the entire surface of the crystal becomes an N-region.

  By doping carbon in this way, it is possible to pull up a single crystal in the N-region at a higher speed than in the case of carbon non-doping, and it is possible to improve the productivity and reduce the cost of a silicon single crystal without a grow-in defect. it can.

In this case, nitrogen can be doped together with carbon during CZ silicon single crystal growth.
In this way, doping nitrogen with carbon increases the pulling speed to become the N-region and can enlarge the N-region, so that the entire crystal surface can improve the productivity and yield of the silicon single crystal in the N-region. It can be improved at the same time.

In this case, it is preferable that the carbon concentration to be doped is 0.1 ppma or more, and the V / G is pulled up while being controlled within the range of 0.183 to 0.177 mm ² / K · min.
In this way, a silicon single crystal in the entire N-region of the crystal can be reliably manufactured at a higher speed and more stably.

The silicon wafer manufacturing method according to the present invention is characterized in that after the silicon single crystal manufactured by the above method is processed into a wafer, heat treatment is performed at a temperature of 600 to 1000 ° C.
Thus, if a single crystal doped with carbon, carbon and nitrogen is processed into a wafer and heat-treated at 600 to 1000 ° C., the wafer is doped with carbon. It is possible to manufacture a wafer whose surface is the entire N-region and which has a high level of IG capability in the wafer plane.

Further, the silicon wafer of the present invention contains 0.1 ppma or more of carbon and consists of the entire N-region.
Thus, by containing 0.1 ppma or more of carbon, oxygen precipitation nuclei that are stable at low temperatures increase, and the entire surface is an N-region and a silicon wafer having sufficient IG capability is obtained.

In this case, the silicon wafer of the present invention preferably contains 1 × 10 ¹³ pieces / cm ³ or more of nitrogen.
Thus, by containing both nitrogen and carbon, a silicon wafer having a sufficiently high density BMD and an extremely high IG ability can be obtained at a high temperature heat treatment and a low temperature heat treatment at an appropriate oxygen concentration.

The method for producing an epitaxial wafer according to the present invention is a method for producing a silicon epitaxial wafer in which an epitaxial layer is formed on the surface of a silicon wafer produced from a CZ silicon single crystal that has been pulled by doping carbon and nitrogen during CZ silicon single crystal growth. In the method, the carbon concentration, nitrogen concentration, and oxygen concentration of the CZ silicon single crystal are 0.1 to 1 ppma, 1 × 10 ¹³ to 1 × 10 ¹⁴ pieces / cm ³ , 15 to 25 ppma, or 1 to ³ ppma, 1 respectively. It is characterized in that the CZ silicon single crystal is pulled up so as to be × 10 ^{14 to} 5 × 10 ¹⁵ pieces / cm ³ and 10 to ¹⁵ ppma.

  Thus, in order to obtain a silicon wafer as an epiwafer substrate, if a single crystal is pulled by doping carbon, nitrogen, and oxygen so that the concentration of carbon, nitrogen, and oxygen is within the above specified range, this is processed. Therefore, an epitaxial layer can be formed on a silicon wafer having sufficient IG capability and free of secondary defects, and a high quality epi wafer can be easily obtained.

Furthermore, an epitaxial wafer according to the present invention is a silicon epitaxial wafer in which an epitaxial layer is formed on a silicon wafer surface produced from a CZ silicon single crystal pulled by doping carbon and nitrogen during CZ silicon single crystal growth. The carbon concentration, nitrogen concentration, and oxygen concentration in the wafer are 0.1 to 1 ppma, 1 × 10 ¹³ to 1 × 10 ¹⁴ pieces / cm ³ , 15 to 25 ppma, or 1 to ³ ppma and 1 × 10 ^{14 to} 5 respectively. × 10 ¹⁵ pieces / cm ³ , 10 to ¹⁵ ppma.

  An epitaxial wafer in which an epitaxial layer is formed using a silicon wafer in which the carbon concentration, nitrogen concentration, and oxygen concentration are controlled within the above specified values as a substrate has no secondary defects, so that the crystallinity of the epitaxial layer formed thereon is improved. It is an excellent high quality epitaxial wafer with excellent IG capability.

In addition, the method for producing an annealed wafer according to the present invention includes a step of performing heat treatment on a CZ silicon wafer produced from a CZ silicon single crystal pulled by doping carbon and nitrogen during CZ silicon single crystal growth. When an annealed wafer having a defect-free layer formed on the surface portion of the wafer and oxygen precipitates of 1 × 10 ⁹ pieces / cm ³ or more in the bulk portion is produced, the carbon concentration, nitrogen concentration, oxygen concentration of the CZ silicon single crystal Are 0.1 to 1 ppma, 1 × 10 ¹³ to 1 × 10 ¹⁴ pieces / cm ³ , 15 to 25 ppma, or 1 to ³ ppma, 1 × 10 ^{14 to} 5 × 10 ¹⁵ pieces / cm ³ , 10 The CZ silicon single crystal is pulled up to 15 ppma.

  Thus, in order to obtain a silicon wafer as a base of the annealed wafer, it is sufficient to dope carbon and nitrogen so that the concentration of carbon, nitrogen, and oxygen is within the above specified range and pull up the single crystal by the CZ method. An annealed wafer having a BMD density and no secondary defects can be easily obtained.

The annealed wafer according to the present invention has a carbon concentration, a nitrogen concentration, and an oxygen concentration of 0.1 to 1 ppma, 1 × 10 ¹³ to 1 × 10 ¹⁴ pieces / cm ³ , 15 to 25 ppma, or 1 to ³ ppma, respectively. An annealed wafer obtained by heat-treating a CZ silicon wafer having a density of 1 × 10 ^{14 to} 5 × 10 ¹⁵ pieces / cm ³ and 10 to ¹⁵ ppma, and a BMD density in a bulk portion is 1 × 10 ⁹ pieces / cm ³ or more. It is characterized by being.

  As described above, an annealed wafer manufactured by performing heat treatment on a silicon wafer in which the carbon concentration, nitrogen concentration, and oxygen concentration are controlled within the specified values described above has a sufficiently high density BMD, a high IG capability, and a wafer. It is a high-quality annealed wafer with excellent surface quality with few defects on the surface and no secondary defects.

  As described above, according to the present invention, it is possible to pull up a single crystal having high IG capability at high speed without generating secondary defects in the entire in-plane N− region. Therefore, the productivity and yield of such a CZ silicon single crystal can be improved, and the production cost can be greatly reduced. Further, since stable oxygen precipitation can be obtained without depending on the crystal position and device process, it is possible to obtain a CZ silicon wafer having a stable gettering ability with little variation in oxygen precipitate density. Furthermore, by producing a CZ silicon wafer with carbon, nitrogen, and oxygen concentrations in appropriate ranges as in the present invention, oxygen precipitation does not disappear even when high-temperature epitaxial growth is performed on the surface, and crystallinity is excellent. An epitaxial wafer having a high IG ability can be manufactured. Similarly, if heat treatment is performed on such a CZ silicon wafer, a defect-free layer can be formed in the surface layer portion, and an annealed wafer having a sufficiently high density BMD in the bulk portion can be produced. Useful.

Hereinafter, although an embodiment of the present invention is described in detail, the present invention is not limited to this.
The present inventors have conceived not only doping nitrogen in order to promote oxygen precipitation in the bulk part but also doping carbon, and investigated and examined this.

(About N-region wafers)
First, the influence of carbon doping on the N-region wafer was investigated.
When growing a CZ silicon single crystal having a diameter of 8 inches, carbon is doped so as to enter about 0.1 ppma crystal, and a CZ silicon single crystal pulling apparatus can be used to grow an entire N-region wafer in an HZ (Hot Zone: furnace) The inner structure was pulled up by gradually changing the pulling speed from 0.8 to 0.5 mm / min (no nitrogen doping).

As a result, in the case of carbon non-doping, the OSF ring disappears at a pulling speed of 0.54 mm / min, and defects due to dislocation loops occur at 0.52 mm / min, whereas carbon is doped. The OSF ring disappeared at 0.65 mm / min, and defects due to dislocation loops occurred at 0.63 mm / min. In other words, it was discovered that the N-region can be obtained at higher speed by doping carbon. At this time, the range of V / G was 0.183 to 0.177 mm ² / K · min. This means that the productivity of the entire N-region wafer is improved by carbon doping. However, if the carbon concentration exceeds 3 ppma, there is a concern about adverse effects on device characteristics, so it is preferable to set the carbon concentration to 3 ppma or less.

  Usually, there are two types of N-regions, an N (V) region located on the V-rich region side where vacancy-type defects are dominant, and a region due to dislocation loops where interstitial silicon is dominant. It is known that N (I) regions located on the I-rich region side coexist, and these two regions have different amounts of oxygen precipitation (see Japanese Patent Application No. 11-322242). In other words, the IG ability differs depending on the in-plane position of the wafer and the cutting position from the crystal.

  The same was true for nitrogen-doped crystals. However, when carbon was doped, it was confirmed from another experiment that the formation of oxygen precipitation nuclei at a low temperature (600 to 1000 ° C.) was confirmed (see Japanese Patent Application No. 2000-048461). By performing such a low-temperature heat treatment, the difference in precipitation between the N (V) region and the N (I) region can be almost eliminated. This indicates that the entire N-region wafer by carbon doping has a stable IG capability at a high level throughout the wafer surface.

Next, nitrogen was doped in addition to carbon, and an experiment similar to the above was performed. As a result, the pulling speed for the N-region increased and expanded. Nitrogen originally had the effect of expanding the N-region, but the pulling speed to become the N-region did not increase, so with these two dopants, the entire N-region wafer simultaneously improved productivity and yield. It shows that. In addition, the effect on oxygen precipitation was remarkably obtained. Nitrogen increased the number of stable oxygen precipitation nuclei at high temperatures, and carbon increased the number of stable precipitation nuclei at low temperatures. This indicates that the effect of promoting oxygen precipitation is strong at various temperature zones. Therefore, regardless of the heat treatment in the device process, high IG capability can be exhibited. Note that a concentration of 1 × 10 ¹⁰ pieces / cm ³ or more is necessary to surely obtain the effect of nitrogen, and 5 × 10 ¹⁵ pieces / cm ³ or less so as not to hinder single crystallization. It is preferable that

Taking these experimental facts into consideration, using the same HZ as in the above experiment, this time, in order to obtain a similar crystal in a long range of crystals, first, 0.1 ppma of carbon and 3 × 10 ¹³ nitrogen / Cm ^3, and the pulling-up speed was raised in the range of 0.65 to 0.62 mm / min. As a result, the lower side of the straight cylinder 20 cm from the upper part (seed crystal side) of the crystal became the N-region. The wafer cut out from this crystal was subjected to a heat treatment at 600 ° C. for 1 hour to promote the formation of oxygen precipitate nuclei, and then subjected to a heat treatment of 800 ° C./4Hr+1000° C./16 Hr to grow oxygen precipitates to grow OPP (Optical When observed by the Precipitate Profiler method, BMD was present in the bulk at a density of 1 × 10 ⁹ pieces / cm ³ or more over the entire wafer surface.

(About epitaxial wafers)
Next, the influence on the BMD density when carbon and nitrogen were doped was investigated and experimented on a silicon wafer for epitaxial growth.
If the nitrogen concentration exceeds 1 × 10 ¹⁴ atoms / cm ³ , the OSF region expands greatly, and LEP is likely to occur. First, doping is performed so that the nitrogen concentration becomes 5 × 10 ¹³ atoms / cm ^3, and carbon is reduced to 0. The crystals were pulled up by doping to 1 ppma. And the wafer was produced from the crystal | crystallization, after performing the heat processing of 800 degreeC / 4Hr + 1000 degreeC / 16Hr and revealing an oxygen precipitate, BMD density was evaluated by OPP method.

As a result, it was found that the initial interstitial oxygen concentration in the wafer is strongly dependent, and the BMD density does not occur in the number of 10 ⁹ units unless it is 15 ppma (Japan Electronics Industry Promotion Association (JEIDA) standard) or more. However, this nitrogen concentration (5 × 10 ¹³ / cm ³ ) is almost free from secondary defects due to nitrogen doping, and stable oxygen precipitation nuclei are formed at high temperatures (1000 ° C. or higher). Even if this epitaxial growth is performed, oxygen precipitation nuclei will not disappear. Therefore, even if the nitrogen concentration is 5 × 10 ¹³ atoms / cm ³ and the carbon concentration is low (0.1 ppma), if the initial interstitial oxygen concentration is 15 ppma or more, a sufficient BMD density is obtained. As a result, a silicon wafer for epitaxial growth free from secondary defects can be obtained. If the oxygen concentration is 15 ppma or more, a necessary and sufficient BMD density can be obtained if the nitrogen concentration is 1 × 10 ¹³ or more. However, if the oxygen concentration exceeds 25 ppma, excessive precipitation occurs and the wafer strength is affected. It is preferable that In order to enhance the effect of oxygen precipitation by carbon, it is preferable to perform a low-temperature heat treatment at about 600 to 1000 ° C. before epitaxial growth.

Subsequently, in order to use a high nitrogen concentration (1 × 10 ¹⁴ atoms / cm ³ or more), a sample with a reduced initial interstitial oxygen concentration was prepared. As described above, even if the nitrogen concentration is high, if the oxygen concentration is lowered to less than 15 ppma, the occurrence of secondary defects can be suppressed, but the actual oxygen precipitation hardly occurs (BMD density <1 × 10 ⁹ / cm ³ ).

Therefore, the carbon concentration was increased to 1.0 ppma. As a result, the BMD density after 800 ° C./4Hr+1000° C./16 Hr was in the lower half of the 10 ⁹ range even at low oxygen concentration of 12 ppma. That is, in the case of this combination (nitrogen concentration of 1 × 10 ¹⁴ atoms / cm ³ and carbon concentration of 1.0 ppma), if the initial oxygen concentration is low, secondary defects do not occur and a high BMD density is obtained. It will be. However, if the carbon concentration exceeds 3 ppma, the device characteristics to be produced may be adversely affected. Therefore, the carbon concentration is preferably 3 ppma or less. Further, the oxygen concentration for obtaining sufficient BMD needs to be 10 ppma or more. The nitrogen concentration is preferably 5 × 10 ¹⁵ atoms / cm ³ or less so as not to hinder single crystallization of the pulled crystal. Also in this case, in order to enhance the oxygen precipitation effect by carbon, it is preferable to perform a low-temperature heat treatment at about 600 to 1000 ° C. before epitaxial growth.

On the other hand, in the case of crystals with a low carbon concentration (0.1 ppma) and a high nitrogen concentration of 1 × 10 ¹⁴ atoms / cm ³ , the initial oxygen concentration is lowered to less than 15 ppma in order to obtain a sufficient BMD density (10 ⁹ units). As a result, secondary defects eventually occurred.

In the case of a high carbon concentration (1.0 ppma) and a low nitrogen concentration (5 × 10 ¹³ pieces / cm ³ ), the BMD density obtained is strongly dependent on the first-stage heat treatment temperature due to the effect of the high carbon concentration. Therefore, the variation in the BMD density increases depending on the heat treatment temperature at the first stage. Therefore, it is desirable to dope nitrogen to a certain extent to form oxygen precipitate nuclei that are stable at high temperatures.

As described above, by adding a certain amount of nitrogen (for example, 1 × 10 ¹⁴ atoms / cm ³ ), the dependence on the first-stage heat treatment temperature is weaker than that of carbon alone, so that the variation in BMD density due to the first-stage heat treatment temperature is small. However, if it passes through a process heat treatment at a very high temperature, the effect of promoting precipitation by carbon is significantly weakened. Therefore, it can be said that the temperature of the epi process for obtaining a high BMD density is desirably a low temperature (1000 ° C. or less).

Similarly, when the low-temperature heat treatment is applied before or after the epitaxial process, oxygen precipitate nuclei grow or new precipitate nuclei are formed, so that the BMD density during the subsequent epi-growth and other device processes increases.
The heat treatment applied before or after the epi is not limited to such a low temperature heat treatment, but a so-called IG heat treatment (for example, a heat treatment including a high temperature heat treatment of 1100 ° C. or higher in the first stage) or an RTA apparatus (Rapid Thermal Annealer; It is also possible to apply high-temperature and short-time heat treatment using a rapid cooling device. If these heat treatment processes are performed, secondary defects generated on the wafer surface can be reduced, so that the carbon, nitrogen and oxygen concentrations can be selected in a wide range.

(About annealed wafers)
Finally, we investigated and experimented on the effect of crystals doped with carbon and nitrogen on the annealed wafer.
Also in the case of the annealed wafer, basically, the combination of low carbon + low nitrogen + high oxygen and high carbon + high nitrogen + low oxygen has a high BMD density and 2 as in the above-described investigation of the silicon wafer for epitaxial growth. It was very effective in suppressing secondary defects. In addition, even if secondary defects occur on the wafer surface, the secondary defects can be eliminated by annealing, so unlike direct epitaxial growth, low carbon + high nitrogen + high oxygen, and high carbon. It was found that an annealed wafer having a sufficiently high density BMD and few defects on the wafer surface can be obtained even in the combination of + high nitrogen + high oxygen. Further, it was found that such an annealed wafer does not cause defects in the epi layer even when the epitaxial layer is formed, and a sufficient BMD density can be obtained.

In order to take advantage of the characteristics of carbon, precipitation nuclei can be increased by applying a low-temperature heat treatment or by suppressing the temperature rising rate during annealing to 5 ° C./min or less, whereby 800 ° C./4Hr+1000° C. In the observation after / 16 Hr, BMD density of 10 ¹⁰ units from the latter 10 ⁹ units could be secured.

As described above, by doping both carbon and nitrogen, it is possible to work to counteract the respective disadvantages of carbon and nitrogen, so it is sufficient for various device processes rather than carbon alone and nitrogen alone. You can earn BMD density.
Table 1 summarizes the above experimental results for nitrogen and carbon doped wafers used for epitaxial wafers and annealed wafers.

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

  For example, in the above-described embodiment, the case where a silicon single crystal having a diameter of 8 inches is grown has been described as an example. However, the present invention is not limited to this, and the present invention is not limited to this. The present invention can also be applied to the above silicon single crystal.

Claims (4)

By performing heat treatment on a CZ silicon wafer produced from CZ silicon single crystal pulled by doping with carbon and nitrogen during CZ silicon single crystal growth, a defect-free layer is formed on the surface layer portion of the CZ silicon wafer, In the method of manufacturing an annealed wafer having 1 × 10 ⁹ pieces / cm ³ or more of oxygen precipitates in the part, the carbon concentration, nitrogen concentration, and oxygen concentration of the CZ silicon single crystal are 0.1 to 1 ppma, 1 × 10, respectively. ^A method for producing an annealed wafer, wherein the CZ silicon single crystal is pulled up to ¹³ to 1 × 10 ¹⁴ pieces / cm ³ and 15 to 25 ppma. 2. The method of manufacturing an annealed wafer according to claim 1 , wherein the CZ silicon single crystal is pulled up so as not to generate secondary defects. A CZ silicon wafer having a carbon concentration, a nitrogen concentration, and an oxygen concentration of 0.1 to 1 ppma, 1 × 10 ¹³ to 1 × 10 ¹⁴ pieces / cm ³ , and 15 to 25 ppma, respectively, is subjected to heat treatment to form a defect-free layer on the surface layer portion. An annealed wafer formed, wherein the BMD density in the bulk portion is 1 × 10 ⁹ pieces / cm ³ or more. 4. An annealed wafer according to claim 3 , wherein the wafer is free of secondary defects.