WO2002000969A1

WO2002000969A1 - Method for producing silicon wafer and epitaxial wafer, and epitaxial wafer

Info

Publication number: WO2002000969A1
Application number: PCT/JP2001/005360
Authority: WO
Inventors: Makoto Iida; Yoshinori Hayamizu; Akihiro Kimura
Original assignee: Shin-Etsu Handotai Co., Ltd
Priority date: 2000-06-26
Filing date: 2001-06-22
Publication date: 2002-01-03
Also published as: TW575696B; JP4102988B2

Abstract

A method of producing a silicon wafer from a silicon single crystal being grown by the CZ method and doped with nitrogen, characterized in that nitrogen is doped in a concentration of 1 X 1014 pieces/cm3 or less, and, in growing the silicon single crystal, the ratio (V/G) of a pulling rate (V) to a solid-liquid interface temperature gradient (G) is adjusted so as to provide a prescribed density of BMD generated after the formation of an epitaxial layer on the silicon wafer produced; a method for producing an epitaxial wafer comprising forming an epitaxial layer on a silicon wafer produced by the method; and an epitaxial wafer produced by this method. Those methods can be employed for producing a substrate for an epitaxial wafer which is suppressed in the generation of crystal defects during epitaxial growth on a silicon single crystal wafer doped with nitrogen having been grown by the CZ method and also has excellent IG capability, and for producing an epitaxial wafer using the substrate.

Description

Detailed Description Manufacturing methods for silicon wafers and epitaxial wafers

Technical field

The present invention relates to a method for manufacturing an epitaxial wafer having extremely few crystal defects in an epitaxial layer and having a gettering effect, a silicon wafer as a substrate thereof, and such characteristics. Regarding Epitaxial X-Aha. Background art

Grown-in defects present in CZ silicon single crystals pulled up by the Czochralski method (CZ method) degrade the oxide withstand voltage characteristics of wafers. It is well known that it causes an isolation failure in a device fabrication process, and various methods have been proposed to avoid these.

For example, a method to reduce the growth defects during single crystal pulling by CZ method, a method to remove surface defects by subjecting the wafer to high-temperature annealing in an atmosphere of hydrogen or argon, or a method of growing an epitaxial layer For example, there is a method using an epitaxy.

With the recent increase in the degree of integration of semiconductor devices, it has become important to reduce crystal defects in semiconductors, particularly near or near the surface. For this reason, the demand for epitaxy wafers having an epitaxy layer having excellent crystallinity on the surface of the wafers has been increasing year by year.

However, when a device is manufactured using an epitaxial wafer, various heat treatment steps are usually performed in addition to the epitaxial growth. Such contaminants are removed from the epitaxy layer as much as possible because Must be eliminated. Therefore, a substrate having a high gettering effect is required as a substrate for epitaxial growth.

There are two types of gettering, extrinsic gettering (EG) and intrinsic gettering (IG). Typical EG methods include a poly back seal (registered trademark) in which a polysilicon film is deposited on the back surface of the substrate, and a method that mechanically damages the back surface. In addition to problems such as dust generation and the like, a special process is required, which is very disadvantageous in cost.

On the other hand, IG generates oxygen precipitates that become gettering sites in the bulk of the substrate by performing a heat treatment on a CZ method silicon wafer containing oxygen. In the case of epitaxy wafers, oxygen precipitate nuclei originally present on the substrate disappeared during epitaxy growth at high temperature, and oxygen precipitates were difficult to form and grow during subsequent device heat treatment. Therefore, there was a problem that gettering ability became insufficient.

Therefore, in the production of conventional epitaxial wafers, a substrate containing a high concentration of boron (p + substrate) has a gettering effect, and a low boron concentration is formed on the p + substrate. Epitaxial layers of (p) were formed: — / p + epitaxy wafers were often used. However, when epitaxial growth is performed on ap + substrate, highly doped boron evaporates from the substrate during epitaxy growth and is incorporated into the epitaxial layer. _c also a problem that will leave taken up by solid phase outward diffusion into the layer, more recently, p as a for CMOS devices - has been increasing demand for Epitaki Sharuue Doha using the substrate, the getter-rings capability Shortage is a problem.

More recently, as a method of obtaining a wafer with reduced grown-in defects near the surface of the CZ wafer, the crystal has been used to improve the easiness of disappearance of defects during high-temperature annealing. By doping with nitrogen and reducing the size of the grown-in void defects, the defects can be more deeply etched by annealing. By using a nitrogen-doped crystal as a substrate in an extinguishing technology and an epitaxial wafer, the formation of oxygen precipitates during device heat treatment is promoted, and the BMD (Bulk Micro D Efficient utilization of the characteristics of nitrogen-doped crystals is being actively pursued, such as technology for manufacturing epitaxy wafers with increased IG capability by increasing the effect.

The Yo I Do nitrogen-doped crystals as an example for use in Epitakisharu growth substrate, JP 1 1 one 1 8 9 4 9 3 JP technique described in the nitrogen 1 0 ¹³ / cm ³ or more A silicon single crystal grown by doping is used for epitaxy. This is because when an epitaxy layer is formed on a substrate that includes an OSF (Oxidation-induced Stacking Faults) region generated in a ring shape by the single crystal pulling condition by the CZ method, The knowledge that oxygen precipitate nuclei in the ring region do not disappear, function as an effective gettering site in the device manufacturing process after the epitaxial formation, and dope nitrogen during single crystal growth This makes it possible to increase the OSF ring width.If the amount of nitrogen to be doped is set to be at least 10 ¹³ / cm ³ , the OSF nuclei effective for gettering will be uniform over the entire single crystal. It was based on the finding that it could be dispersed into

However, according to the investigations by the present inventors, it was found that when an epitaxial layer was formed on a nitrogen-doped wafer, the epitaxial layer was

It is clear that defects that are harmful to devices, called LPD (Light Point Defect: a general term for bright spot defects observed by an aerial surface inspection device using laser light), are likely to occur in devices. It was ok. Also, it was found that this LPD was particularly remarkably observed when the nitrogen concentration was high (1 XI 0 ¹⁴ cells / cm ³ or more). The higher the nitrogen concentration, the higher the BMD density in the pulp generated during the deposition process and the higher the IG capability.However, the defects observed on the surface of the Dozens to hundreds are generated in 20 O mm wafers, and epitaxy layer The problem was that the integrity of the system was compromised.

Therefore, as a countermeasure, it is conceivable to reduce the nitrogen concentration to 1 XI 0 ¹⁴ / cm ³ or less, but in this case, the defects on the epi surface are few and the surface integrity is high, but the oxygen precipitation As a result, the effect of improving the IG capability due to the promotion of IG will be weakened. In particular, the BMD was reduced around the periphery of the wafer, and the gettering ability was not sufficient. Disclosure of the invention

Therefore, the present invention has been made in view of such problems, and when performing epitaxial growth on a nitrogen-doped CZ silicon single crystal wafer, a crystal defect generated in the epitaxial layer (hereinafter referred to as an epitaxy). The present invention aims to provide a substrate for an epitaxy wafer having excellent IG capability, an epitaxy wafer using the substrate, and a method of manufacturing the same. And

In order to solve the above-mentioned problems, a method for producing a silicon wafer according to the present invention includes growing a silicon single crystal doped with nitrogen by a CZ method, and forming the silicon single crystal from the silicon single crystal. In the method of manufacturing a silicon wafer, the concentration of nitrogen to be doped is set to 1 XI 0 ¹⁴ pieces / cm ³ or less, and the silicon nitride is manufactured so that BMD generated in the manufactured silicon wafer has a predetermined density. It is characterized by setting the ratio (V / G) between the pulling speed V and the solid-liquid interface temperature gradient G when growing a single crystal.

As described above, in order to manufacture a silicon wafer for obtaining an epitaxy wafer having an extremely small generation of epi defects and a sufficient guttering effect, the nitrogen concentration must be 1 × 10 ¹⁴ / cm ³ or less to suppress the generation of epi defects and heat treatment at 800 ° C for 4 hours and at 100 ° C for 16 hours after epitaxial growth If the VG during single crystal growth is set to a sufficiently high value so that the BMD generated at the same time becomes a predetermined density, the BMD for generating the BMD density that can obtain a sufficient gettering effect in the device process It turned out that a nucleus could be obtained. You In other words, for nitrogen-doped crystals, they found that the value of VZG, which is the condition for growing single crystals, and the BMD density generated by heat treatment after epitaxial growth were significantly correlated.

Here, the required BMD density differs depending on the type of the produced depiice, but the density is preferably at least 1 × 10 ⁸ Z cm ³ . Thus, B MD is a setting child the VZG value in earthenware pots by the 1 XI 0 ⁸ pieces Z cm ³ or more desired density. Specifically, silicon wafers were prepared from crystals with a nitrogen concentration of 1 XI 0 ¹⁴ / cm ³ or less and V / G pulled under various conditions, and the desired epitaxy layers were formed on these silicon wafers. The correlation between the VMD and the BMD density obtained by measuring the BMD density later can be obtained in advance, and VNOG can be set based on this correlation. In this case, in order to obtain a sufficient oxygen precipitation accelerating effect by nitrogen doping concentration of nitrogen correct preferred that the this is 1 X 1 0 ¹² atoms Z cm ³ or more

In this case, it is preferable that the VZG be at least 0.3 mm ² / K · min in the radial direction of the silicon single crystal to be grown in a range of at least 90%.

In this way, if the V / G to be set is set to 0.3 mm ² / K min or more, it is possible to obtain a BMD density that shows a sufficient gettering effect in the device process. You.

In this case, the V / G variation can be in the range of ± 0.015 mm ² / K · min in the radial direction of the silicon single crystal to be grown.

In this way, by designing the HZ (hot zone, in-furnace structure) that makes the in-plane distribution of V / G uniform and growing the crystal, the in-plane distribution of the BMD becomes uniform. Silicon diene can be manufactured. That is, it is possible to manufacture an A wafer having a uniform gettering effect in the A wafer plane.

Further, in this case, the concentration of nitrogen to be doped can be set to 1 XI 0 ¹³ / cm ³ or more. As described above, as an index indicating a sufficient gettering effect in a certain device process, if the BMD density of 5 × 10 ⁸ Z cm ³ or more is required over the entire surface of the wafer, doping is performed. It is preferable that the nitrogen concentration be 1 XI 0 ¹³ / cm ³ or more.

The method of manufacturing an epitaxial wafer according to the present invention is characterized in that an epitaxial layer is formed on the silicon wafer manufactured by the manufacturing method.

In this way, epitaxy wafers with few defects on the surface of the epi and high integrity of the surface layer, promoted oxygen precipitation, increased BMD density and extremely high IG capability can be manufactured. It can be.

According to the present invention, there is provided an epitaxy wafer having an extremely high IG capability and having an epi layer free of epi defects produced by the production method.

Further, according to the present invention, when the silicon wafer on which the epitaxial layer is formed is subjected to heat treatment at 800 ° C. for 4 hours and at 1000 ° C. for 16 hours, , an E pita press Norre © er Ha 5 XI 0 ^s pieces / cm ³ or more B MD occurs during Bruno torque of shea Li co Nueha a substrate, the crystal defects in the surface layer of the E pin Taki interstitial © er Ha 0.06 4 pieces. ₁₁ 1 ² E pita press roux er c to a be characterized and this less is provided.

The crystal defects on the surface of the epitaxy layer observed by the particle counter include at least dislocation loops and epi-stacking faults (SF).

In this case, Ru can and child to the nitrogen concentration in the silicon Konueha and ^{1 XI 0 13 ~ 1 XI 0} 14 pieces / cm ^3.

Thus, by specifying the nitrogen concentration of the silicon wafer, an epitaxy wafer having a high IG capability and forming an epi layer with few epi defects is provided.

According to the present invention, a silicon wafer having a dislocation loop density of 20 cm ² or less on the surface of the silicon wafer serving as a substrate is provided. Since an epitaxy wafer having a layer formed thereon is provided, an epitaxy wafer with few epi defects can be reliably obtained.

Further, by setting the OSF density of the surface of the silicon wafer serving as the substrate to be less than 100 / cm ^{2, the} silicon wafer having a small number of oxygen precipitates which are a nucleus of OSF generation is provided. Nevertheless, an epitaxy wafer having high density BMD, high gettering ability and extremely few epi defects is provided.

As described above, according to the present invention, when epitaxial growth is performed on a nitrogen-doped CZ silicon single crystal wafer, crystal defects generated in the epitaxial layer are suppressed as much as possible, and an excellent IG It is possible to provide a substrate for an epitaxial wafer having a capability, an epitaxial wafer using the substrate, and a method for manufacturing the same. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows the in-plane distribution of V / G when pulling a CZ silicon single crystal doped with 2 × 10 ¹³ nitrogen / cm ^{3 of} nitrogen (the pulling speed was 1. I mmZm in and 1. S mmZm i ii).

Figure 2 shows a silicon mirror wafer fabricated from a silicon single crystal ingot pulled under the pulling conditions shown in Figure 1, and a 5 / xm epitaxial layer was formed on this at 125 ° C. Thereafter, heat treatment is performed at 800 ° C for 4 hours and at 1000 ° C for 16 hours to grow the BMD to a detectable size, and the in-plane BMD density is measured using an OPP device. It is a result figure showing the result of measurement. FIG. 3 is a graph showing the in-plane distribution of VZG when a CZ method silicon single crystal doped with ³ × 10 ¹³ nitrogen / cm ^{3 of} nitrogen was pulled in Example 1. Were 1.2 mm / min and 1.0 mm / min).

4, to prepare a silicon co down mirror © et Doha Ass co down monocrystalline Lee Ngo' preparative pulled up at pulling conditions of FIG. 3, this to 1 1 2 ⁵ ° Epitaki Shall layer of 5 μ πι with C Once formed, the BMD is grown to a detectable size. FIG. 9 is a result diagram showing the results of measuring the in-plane BMD density using an OPP device after heat treatment at 100 ° C. for 4 hours at 1000 ° C. for 16 hours. Fig. 5 shows the crystal diameter direction of G during single crystal pulling in each of single crystal pulling apparatuses A (Examples 2 and 5, Comparative Examples 1 and 2), B (Example 3) and C (Example 4). FIG. 4 is a diagram showing an in-plane distribution of the.

FIG. 6 is a diagram showing the in-plane distribution of VZG when pulling a nitrogen-doped CZ method silicon single crystal in Examples 2 to 5 and Comparative Examples 1 and 2.

FIG. 7 is a schematic explanatory view of a single crystal pulling apparatus by the CZ method used in the present invention.

FIG. 8 is a schematic explanatory view of a single crystal pulling apparatus by the MCZ method used in the present invention.

FIG. 9 is a schematic explanatory view of a usual single crystal pulling apparatus used in the present invention.

FIG. 10 is a diagram showing the OSF density distribution of the silicon wafer manufactured in Example 6.

FIG. 11 is a diagram showing the in-plane distribution of the BMD density of the epitaxy wafer manufactured in Example 6. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail.

In order to achieve both the defect-free completeness of the surface layer of the epitaxial layer and the IG capability in Balta, which are the objects of the present invention, two methods are conceivable. Immediately, a high nitrogen concentration is sufficient to generate BMD sufficiently and other methods reduce epipi defects, or a low nitrogen concentration suppresses epi defects and increases BMD other methods.

Among them, the former method of increasing the nitrogen concentration will be described first. As described in WO 01/27736 2 A1 previously filed by the present applicant, dislocation loops and stacking faults (including SF) are present in epi defects that appear on the surface of the epi layer. ). In addition, since most of the epi defects were dislocation loops, WO 01/27336 A1 was proposed as a method for reducing the dislocation loops. Therefore, the dislocation loop, which is the majority of the epi defects, could be reduced as much as possible by this method. As a result, the LPD (Light

Po int D e f e c t: (a collective term for bright spot defects observed by an aerial surface inspection system using laser light).

However, it is not always easy to apply such a method to the entire length of a silicon ingot, and it has disadvantages in cost. Naturally, it is preferable to minimize the number of epi defects as much as possible. For this purpose, it was necessary to suppress not only the dislocation loop but also the generation of SF.

Therefore, the present inventors have conducted intensive studies on the latter method, that is, whether or not both epi defects (dislocation loop and SF) can be reduced at a low nitrogen concentration and BMD cannot be increased by other methods. VG (the pulling speed V for growing a silicon single crystal and the solid-liquid interface temperature gradient G in the growth axis direction between the melting point of silicon and 140 ° C) It has been found that there is a great correlation between the in-plane distribution of () and the in-plane distribution of the BMD density after epitaxial growth, and the present inventors have completed the present invention by examining various conditions.

Figure 1 shows the V when a CZ silicon single crystal doped with 2 × 10 ¹³ nitrogen / cm ³ (calculated at the shoulder of the pulled crystal) was pulled up using a pulling device. 6 is a diagram showing an example of an in-plane distribution of / G (two conditions of a pulling speed of 1.1 mm Z min and 1.3 mm / min). As can be seen from Fig. 1, under these pulling conditions, V / G decreases toward the periphery of the pulled crystal. The oxygen concentration of the crystal was in the range of 12 to 15 ppma (JEIDA: Japan Electronic Industry Development Association standard).

On the other hand, Fig. 2 shows a silicon mirror wafer fabricated from the silicon single crystal ingot pulled under the pulling conditions shown in Fig. 1, and then a 5 / m epitaxial layer was formed at 125 ° C. Later, to grow the BMD to a detectable size Apply heat treatment at 800 ° C for 4 hours at 1000 ° C for 16 hours and measure the in-plane BMD density using an OPP (Otical Precipitate Profiler) device. It is shown. As shown in Fig. 2, even with a relatively low concentration of nitrogen in the 13th power range, the BMD density near the center of e-ha has a somewhat high BMD density, and the distribution is lower in the periphery. In other words, the tendency of the in-plane distribution of V / G and the in-plane distribution of BMD after epitaxy growth match, indicating that high V / G 髙 BMD.

Further, these figures 1, from 2, to B MD density is one measure of order to have a sufficient getter-ring effect, to achieve a 5 XI 0 ⁸ pieces Z cm ³ or more, V / It can be seen that G should be approximately 0.3 mm ² / K min or more.

To confirm this, the structure inside the furnace (HZ _: hot zone) and the pulling speed of the pulling device were adjusted, and the in-plane distribution was flat when V_ / G was about 0.43 mm ² / Κ · min. (G is about 2.8 K / mm, pulling rate is 1.2 mm / min), and nitrogen is applied to the shoulder at 2X position (0.43 ± 0.015). A crystal was grown by doping to 10 ¹³ Z cm ^3, and the BMD after epi growth was observed by the same method as described above. The BMD density was approximately 2 × 10 ⁹ The in-plane distribution was almost uniform for each piece of Z cm ³ .

In order to make VZ G 0.3 mm ² / K min or more as described above, first, for example, a method of increasing the pulling speed by using HZ in which the in-plane distribution of G is flat is used. is there. This case can be achieved regardless of the ordinary CZ method or the so-called MCZ method in which a magnetic field is applied. With this method, the in-plane distribution of the BMD after the epitaxial growth is also stable.

Even if the in-plane distribution of G is not flat, if the minimum value of VG just needs to exceed 0.3 anyway, no matter what kind of G distribution HZ is used, pulling up Anyway, it is sufficient to raise the speed so that VZ G exceeds 0.3 mm ² / K · min. In this case, the MCZ method can be achieved more easily. The reason is that the maximum pulling speed that can be grown without deforming the pulled crystal is higher in the MCZ method than in the normal CZ method. Is also a force that is fast with respect to G. However, in such a case, the BMD after epitaxy growth has an in-plane distribution as well as the V-no-G has an in-plane distribution. However, it is possible to make the minimum density of the BMD about 5 × 10 8 [pieces / _cm ³ ] depending on the pulling conditions, and it will have sufficient IG capability over almost the entire surface of the wafer. In the case of epitaxial growth on a nitrogen-doped substrate, the BMD density after the epitaxial growth does not largely depend on the oxygen concentration of the substrate before the epitaxial growth, and is 11 to 16 ppma. (JEIDA) There is no big difference.

As described above, the VZG value is better if it is larger than 0.3 mm ² Κ · min.However, if it is too large, the crystal will be deformed. ^The limit is about ² / K · min.

Hereinafter, the single crystal pulling apparatus used in the present invention will be described with reference to the drawings.

First, FIG. 7 shows a configuration example of a single crystal pulling apparatus for making the VZG flat in the plane (that is, the solid-liquid interface temperature gradient G flat in the radial direction) in the present invention. Will be explained. As shown in FIG. 7, the single crystal pulling apparatus 30 includes a pulling chamber 31, a crucible 32 provided in the pulling chamber 31, and a heater 3 arranged around the crucible 32. 4, a crucible holding shaft 33 for rotating the crucible 32 and its rotation mechanism (not shown), a seed chuck 6 for holding a silicon seed crystal 5, and a seed chuck 6 pulled up It comprises a wire 7 and a winding mechanism (not shown) for rotating or winding the wire 7. The crucible 32 is provided with a quartz crucible on the inner side for containing the silicon melt (hot water) 2 and a graphite crucible on the outer side. Further, a heat insulating material 35 is arranged around the outside of the heater 34.

Further, in order to set the manufacturing conditions (flat G in the plane) relating to the manufacturing method of the present invention, an annular solid-liquid interface heat insulator 8 is provided on the periphery of the solid-liquid interface of the crystal, Upper surrounding insulation 9 is arranged. The solid-liquid interface insulation 8 has a gap 10 to 5 cm between its lower end and the surface of the silicon melt 2. Is installed. The upper surrounding insulation 9 may not be used depending on the conditions. Further, a cylindrical cooling device 36 for spraying a cooling gas or cooling the single crystal by blocking radiant heat may be provided.

Separately, recently, as can be seen in FIG. 8, a magnet 38 made of a normal conducting or superconducting coil is installed outside the pulling chamber 31 in the horizontal direction, and the horizontal or vertical direction is applied to the silicon melt 2. The so-called MCZ method, which suppresses the convection of the melt and stably grows a single crystal by applying such a magnetic field, is often used. The direction of the magnetic field applied to the melt can be easily changed by the arrangement of the magnet. For example, if one coil is arranged so as to surround the pulling chamber 31 in the horizontal direction, a vertical magnetic field (vertical magnetic field) is applied to the melt, and the two coils are pulled up. If the chamber 31 is placed facing the outside in the horizontal direction, a horizontal magnetic field (transverse magnetic field) will be applied to the melt. Also, in the present invention, as described above, by using the MCZ method, the maximum pulling speed that can be grown without causing deformation of the pulled crystal is made higher than that of the ordinary CZ method. be able to.

On the other hand, if the minimum value of VZG is more than 0.3 mm ² / 良い min even if G is not flat, no matter what G distribution HZ is used, Since it is only necessary to increase the pulling speed, a single crystal pulling apparatus generally used as shown in FIG. 9 can be used. The basic structure is the same as that of the pulling device shown in Fig. 7, but the solid-liquid interface insulation 8 ^ the upper surrounding insulation 9 is not provided. A magnet may be installed in the device shown in Fig. 9 to pull the crystal at a high VZG by the MCZ method.

Next, a method for growing a single crystal using the single crystal pulling apparatus 30 of FIG. 7 will be described. First, in a crucible 32, a high-purity polycrystalline silicon raw material is heated to a melting point (about 140 ° C.) or more and melted. Next, the tip of the seed crystal 5 is brought into contact with or immersed substantially in the center of the surface of the melt 2 by unwinding the wire 7. Thereafter, the crucible holding shaft 33 is rotated in an appropriate direction, and the wound seed crystal 5 is pulled up while rotating the winding 7 to start single crystal growth. . After that, we decided to adjust the pulling speed and temperature appropriately. Thus, a substantially cylindrical single crystal rod 1 can be obtained.

As shown in Fig. 7, a predetermined gap is provided at a position directly above the liquid surface, a heat insulating material is arranged, and a device for cooling the crystal is provided above this heat insulating material. In the vicinity of the growth interface, a heat retention effect is obtained by radiant heat, and radiant heat from a heater or the like can be cut above the crystal, so that the temperature gradient Ge around the crystal becomes small. As a result, there is no difference from the temperature gradient Gc at the center of the crystal, and a flat in-plane distribution of the temperature gradient G can be obtained. As a cooling device for the crystal, an air-cooled duct surrounding the periphery of the crystal, a water-cooled snake tube or the like is provided separately from the cylindrical cooling device 36 to secure a desired temperature gradient. May be.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited to these.

(Example 1)

Using a single crystal pulling device similar to that in Fig. 8, a predetermined amount of the raw material polycrystalline silicon and silicon wafer with nitride film were charged into a quartz crucible with a diameter of 18 inches (450 mm). crystal orientation of <1 0 0>, conductivity type p-type, pull the sheet re co down monocrystalline I Ngo' preparative nitrogen concentration 3 X 1 0 ¹ ³ pieces / cm ³ (calculated value at the position of the pulling crystal shoulder) ( A magnetic field was applied by the MCZ method), and a wafer was cut out from near the shoulder of this single crystal ingot, and a silicon mirror surface wafer with a resistivity of 10 Ω · cm and a diameter of 150 mm was cut out. Was prepared. The oxygen concentration was between 12 and 15 ppma (JEIDA).

The pulling speed was set under two conditions of 1.2 mm /: min and 1.0 mm / min. Figure 3 shows the in-plane distribution of V / G in the crystal diameter direction during crystal pulling. The calculation of V / G is based on the integrated heat transfer analysis software FEMAG (F. D upret, P. N icodeme, Y. Ryc K mans, P. Outersand M. J. Crochet, Int. J.Heat Mass Transfer, 33, 1849 (1900) was used, taking into account the HZ of the lifting device. As is clear from FIG. 3, the in-plane distribution of V / G has a uniform value, and is about 0.36 ± 0.01 mm when the pulling speed is 1.0 Omm / min. .. ² / K min range, 1 in the case of S mmZm in about 0 4 3 ± 0 0 1 5 mm 2 / K - ranged min...

After forming a 5 μm epitaxial layer on the fabricated silicon substrate at 112 ° C, the size was reduced to 0.1 μm using a surface inspection system SP-1 manufactured by KLA-Tencor. The above defects (LPD) were measured. The observed LPD was very low, about several pieces / ゥ eah in each case.

In addition, these epitaphic wafers can be stored at 800 ° C for 4 hours + 10

Heat treatment was performed at 00 ° C for 16 hours to grow oxygen precipitates to a detectable size, and the BMD density was measured using a Bio-Rad OPP device. Figure 4 shows the measurement results. As shown in FIG. 4, the obtained BMD densities were uniform in the plane, and all of them exceeded 5 × 10 ⁸ cm ³ , indicating that there was a sufficient gettering effect. understood.

(Examples 2 to 5, Comparative Examples 1 and 2)

Six types of nitrogen-doped silicon single crystals (crystal orientations of 100>) using three types of single crystal pullers with different HZ (device A (with no magnetic field applied), devices B and C (with magnetic field applied)) , Conductivity type p-type), and a wafer was cut out from near the shoulder of these single crystal ingots to produce a silicon mirror surface wafer with a resistivity of 10 Ωcm and a diameter of 20 Omm. . The oxygen concentration of each of the ゥ eno's was in the range of 11 to: L6ppma (JEIDA).

Fig. 5 shows the in-plane distribution of G in the crystal diameter direction during the crystal pulling for each of the devices A, B, and C. For the device A, the pulling speed was determined under three conditions (1.3, 1.1, 1.0) mm / mi II) to pull up three crystals (Example 2, Example 5, and Comparative Example 1, respectively). For devices B and C, the crystals were pulled at the maximum speed at which the crystals were not deformed during the pulling. 3, Example 4). In addition, except that the nitrogen concentration was different from that in Example 2, pulling was performed under the same pulling conditions. This was designated as Comparative Example 2. Figure 6 shows the in-plane distribution of VZG when these six types of crystals were pulled.

Table 1 summarizes these six types of crystal pulling conditions and the evaluation results of the quality of the fabricated substrate and epitaxial layer. The method of evaluating each quality was the same as in Example 1, except that the dislocation loops of the substrate were observed with an optical microscope after the substrate was secco-etched, and the SF of the epi layer was the defect observed as LPD. It was measured by observation with an optical microscope.

(table 1 )

From the results of Table 1 of Example 2-4, the nitrogen concentration is ³ hereinafter 1 X 1 0 ¹⁴ atoms Z cm, VZG is ^{0. 3 mm 2 / K ·} min or more regions in the radial direction toward the crystal If it is 90% or more, no dislocation loop is observed on the substrate, and the density can be made ²⁰ or less / cm ² or less. As a result, it is found that defects (LPD) containing SF in the obtained epi layer can be significantly reduced to 20 or less wafers. In addition, as in Example 4, the in-plane distribution of V / G is 0. When it is in the range of 43.5 ± 0.015 mm ² / Κ · min, it can be seen that the in-plane distribution of the BMD becomes uniform, and that the gettering effect is uniform in the plane. Example 5 is an example in which the region where V / G is not less than 0.3 mm ² ZK ′ min is less than 90% in the radial direction of the crystal.In this example, V / G is 0.3. mm ² / kappa · near 1 is a region of less than min 0 point mm B MD density that put around the small (3 1 0 ⁸ Bruno <: 111 ³⁾ only in comparison with examples 2-4 in effect However, there is no problem if the lower limit of the BMD density required in device fabrication is about ³ × 10 ⁸ / cm ³ . That is, even if the area where V_G is 0.3 mm ² ZK.min or more is not necessarily 90% or more, the LPD force of the epi layer 20 pieces Z 2 according to the required BMD density It can be seen that V / G should be controlled so as to be equal to or less than 0.0 mm ゥ aha (0.064 Zcm ² ).

On the other hand, Comparative Example 1 is an example in which the area where V / G is 0.3 mm ² / Κ · min or more is about 40%. Dislocation loops specific to the substrate were observed, resulting in an increase in the LPD of the epi layer. Similarly, Comparative Example 2 resulted in a large amount of LPD even when the nitrogen concentration was 1 XI 0 ¹⁴ / cm ³ or more. (Example 6)

A silicon mirror surface wafer fabricated under the same conditions as in Example 4 was subjected to a thermal oxidation treatment at 110 ° C. for 16 hours in a dry oxygen atmosphere, and then subjected to selective etching. To measure the OSF density. The OSF density was measured from the outer edge of the wafer to the center of the wafer at _{5 mm} intervals (Fig. 10). Further, using another silicon mirror surface 18 cut out from an adjacent position of the same ingot as the ingot in which the wafer was manufactured, as in Example 1, An epitaxy wafer was prepared and the LPD of the epitaxy layer surface was measured. The number of LPDs observed was as low as 5 pcs / cm2. In addition, the BMD density of this epitaxy The internal distribution was measured by the same method as in Example 1 (Fig. 11).

According to the results of FIG. 10 and FIG. 11, according to the present invention, oxygen precipitates which are originally present in the silicon wafer forming the epitaxial layer and serve as nuclei for OSF generation are 100 / cm ^2. It can be seen that an epitaxy wafer having a high density of BMD and high gettering ability can be obtained even if the silicon wafer is used in a small amount. Note that the present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the claims of the present invention. However, they are also included in the technical scope of the present invention.

Claims

Scope of Claim 1. In a method of growing a silicon single crystal doped with nitrogen by the cz method and manufacturing a silicon wafer from the silicon single crystal, the concentration of nitrogen to be doped is set to 1 × 10 10 The pulling speed for growing the silicon single crystal so that the BMD generated after forming the epitaxial layer on the manufactured silicon wafer has a predetermined density is ¹⁴ pieces / cm ³ or less. A method for manufacturing a silicon wafer, comprising setting a ratio (VZ G) of a temperature gradient G to V and a solid-liquid interface.

2. The V / G is characterized in that at least 0.3 mm ² / K · min or more in the radial direction of the silicon single crystal to be grown is at least 90%. The method for producing a silicon wafer according to claim 1.

3. The method according to claim 1, wherein the variation of V / G is within a range of ± 0.015 mm ² / K-min in a radial direction of the silicon single crystal to be grown. The method for producing a silicon wafer described in the above.

4. The method for producing a silicon wafer according to any one of claims 1 to 3, wherein the concentration of the nitrogen to be doped is 1 XI 0 ¹³ / cm ³ or more.

5. A method for manufacturing an epitaxy wafer, comprising forming an epitaxy layer on a silicon wafer manufactured by the manufacturing method according to any one of claims 1 to 4.

6. An epitaxy nanoreagent manufactured by the manufacturing method according to claim 5.

7. When the silicon wafer on which the epitaxial layer is formed is subjected to heat treatment at 800 ° C for 4 hours and at 1000 ° C for 16 hours, the silicon An epitaxy wafer in which BMD of 5 × 10 ⁸ Z cm ³ or more is generated in the nozzle of the condensate wafer, and the crystal defects on the surface layer of the epitaxy wafer are 0%. 0 6 4 pieces 0! 11 ² or less.

8. The epitaxy wafer according to claim 7, wherein the nitrogen concentration in the silicon wafer is 1 × 10 ¹³ to 1 × 10 ¹⁴ / cm ³ .

9. The epitaxy laser according to claim 7 or 8, wherein the density of dislocation loops on the surface of the silicon wafer is 20 / cm ² or less.

1 0. E pita press roux et chromatography described claims 7 to any one of claims 9 to OSF density of the silicon Konue Doha surface, characterized in that it is a less than 1 0 0 Z cm ² C.