WO2008029579A1 - Silicon single-crystal wafer and process for producing the same - Google Patents

Abstract

A silicon single-crystal wafer grown according to the CZ method, doped with nitrogen so as to treat the whole surface into N-region, which silicon single-crystal wafer exhibits a nondefective rate of 90% or higher in TZDB performance and TDDB performance and exhibits a BMD density maximum value/minimum value ratio of 50 or below within the wafer plane after gettering heat treatment or device heat treatment. Further, there is provided a process for producing a silicon single-crystal wafer through growing of silicon single-crystal according to the CZ method wherein crystal upward pull is performed under such conditions that the crystal whole surface becomes N-region while doping the same with nitrogen of 5×1011 to 3×1013 atoms/cm3 concentration and oxygen of 8 to less than 13 ppma (JEIDA) concentration. Accordingly, the provided silicon single-crystal wafer and process for producing the silicon single-crystal wafer would realize excellence in the TZDB performance and TDDB performance on a wafer surface-layer region as a device fabrication region and lowering of the dispersion of BMD density in the wafer plane.

Description

 Specification

 Manufacturing method of silicon single crystal wafer and silicon single crystal wafer 8

 The present invention relates to a silicon single crystal wafer used as a substrate for a semiconductor device such as a memory or a CPU, and a method for manufacturing the silicon single crystal wafer. Particularly, the surface layer used in the most advanced field has a defect-free silicon. The present invention relates to a method for producing a single crystal wafer and a silicon single crystal wafer.

Background art

 [0002] In recent years, with the miniaturization of elements due to the high integration of semiconductor circuits such as DRAM, a silicon single crystal manufactured by the Tjoklarsky method (hereinafter sometimes abbreviated as CZ method) as its substrate The quality requirements for are increasing. In particular, there are defects due to single crystal growth that deteriorate the oxide breakdown voltage characteristics and device characteristics called Grown-in defects such as FPD, LSTD, COP, etc., and it is important to reduce their density and size. Has been

In describing these defects, first, there are vacancy-type point defects called vacancy (hereinafter sometimes abbreviated as V) incorporated into a silicon single crystal, and interstitial silicon (Si). The factor that determines the concentration of each interstitial silicon point defect, called “I” (sometimes abbreviated as “I”), is explained in general.

[0004] 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 due to the presence of extra silicon atoms. This is a region where there are many dislocations and excess lumps of silicon atoms, and there is no shortage or excess of atoms between the V region and the I region (neutral region, hereinafter N It may be abbreviated as “region”. The grow-in defects (FPD, LSTD, COP, etc.) occur only when V and I are supersaturated. Even if there is a slight atomic bias, If it is less than the sum, it has been found that there is no Groin In defect!

 [0005] It is known that the concentration of both point defects is determined by the relationship between the crystal pulling rate (growth rate) in the CZ method and the temperature gradient G in the vicinity of the solid-liquid interface in the crystal. In addition, the N region between the V region and the I region contains OSF (oxidation induced stacking fault, Oxidation Indused

The existence of a ring-like defect called “Stacking Fault” has been confirmed.

 [0006] When these defects due to crystal growth are classified, when the force due to the diameter of the grown crystal, for example, when the growth rate is relatively high, such as about 0.6 mm / min or more, vacancy-type point defects are collected. Groin-in defects such as FPD, LSTD, and COP, which are attributed to voids, exist at high density throughout the crystal diameter direction, and the region where these defects exist is called the V-rich region. In addition, 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 decreases. (Large Dislocation: Abbreviation of interstitial dislocation loop, LSEPD,

LFPD and other defects are present at low density, and the area where these defects exist is called the I-rich area. Furthermore, when the growth rate is reduced to about 0.4 mm / min or less, the OSF ring aggregates and disappears at the center of the wafer, resulting in a full-area _SI -rich region.

[0007] Also, recently, FPD, LSTD, COP due to vacancy, LSEPD, LFPD due to dislocation loop, and OSF are not present outside OSF ring between V rich region and I rich region N —The existence of an area has been discovered. This region is outside the OSF ring, and when oxygen precipitation heat treatment is performed and the contrast of precipitation is confirmed by X-ray observation or the like, there is almost no oxygen precipitation and LSEPD and LFPD are formed. Not rich I is on the rich side.

 Furthermore, there are no defects due to vacancies or dislocation loops inside the OSF ring, and there is no OSF! /, The existence of the N-region! /.

[0008] In the normal method, these N regions exist obliquely with respect to the growth axis direction when the growth rate is lowered, and therefore exist only in a part of the wafer plane.

For the N region, the Boronkov theory (V.V.Voron Voronkov Journal of Crystal Growth, 59 (1982) 625-643) is the ratio of the pulling rate (F) and the temperature gradient (G) in the axial direction of the crystal solid-liquid interface. When F / G and! /, Parameters determine the total density of point defects Chanting. Considering this, the pulling speed should be constant in the plane, so that 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. I was able to obtain only crystals that would be rich regions.

[0009] Therefore, recently, when the in-plane G distribution was improved and the N region that existed only in the oblique direction was lifted, for example, while the pulling rate F was gradually decreased, the N region was changed at a certain pulling rate. Crystals spread across the entire horizontal surface can be manufactured. Also, in order to enlarge 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 maintaining the pulling speed when the N region spreads sideways. Also, considering that G changes as the crystal grows, correct it and adjust the pulling speed so that the F / G is constant, so that the entire N region can be used in the growth direction. It became possible to enlarge the crystal.

 [0010] However, such wafers have the feature that even in the N region where no defect is detected, oxygen precipitation is likely to occur on the V-rich side and oxygen precipitation is unlikely to occur on the I-rich side. . Therefore, when a wafer is cut out from such a crystal, there are a mixture of parts where oxygen precipitation is likely to occur and parts where it is difficult to occur in the wafer surface, and the density of BMD observed after device heat treatment etc. There was a problem that there were large variations.

[0011] In addition, when trying to manufacture the N region, which is an extremely low defect region as described above, over the entire crystal, the in-reactor structure of the crystal growth apparatus has a narrow control range of the pulling rate that becomes the N region. Since the (hot zone: HZ) is also limited, it was difficult to stably expand the N region in the axial direction of the crystal.

 Therefore, it is difficult to guarantee the quality of the crystal, which has a low yield in the production of crystals in the entire N region.

On the other hand, Japanese Patent Application Laid-Open No. 2000-53497 discloses that doping the nitrogen expands the N-region, and the N region can be easily and easily controlled. A method for improving the controllability of the N region using the characteristics of the above is disclosed. In addition, wafers cut out from the N-region obtained in this way have been reported to have high non-defective rates such as TZD Brime Zero Dielectric Breakdown) and TDDB fime Dependent Dielec trie Breakdown). S, the inventors have tried again As a result, it was found that even if TZDB is actually good, TDDB failure may occur.

 [0013] In addition, the value disclosed in JP-A-2005-159028,

 11 Even though it is disclosed in Gazette No. 195565! /, There is a case where a defect occurs in the TDDB characteristic. Disclosure of the invention

 [0014] The present invention has been made in view of the above problems, and has excellent TZDB characteristics and TDDB characteristics in the wafer surface layer region, which is a device fabrication region, and a small variation in BMD density in the wafer surface. An object of the present invention is to provide a silicon single crystal wafer and a method for producing the silicon single crystal wafer. In particular, the aim is to provide a silicon single crystal wafer having excellent IG capability, in which a uniform and sufficient BMD is formed in the wafer haulta region.

 [0015] In order to achieve the above object, the present invention provides a silicon single crystal wafer grown by the Chiyoklarsky method, which is doped with nitrogen and has an entire N region, and has TZDB characteristics and Non-defective product ratio of TDDB characteristics is 90% or more, and the ratio (maximum value / minimum value) of maximum and minimum BMD density in wafer plane after gettering heat treatment or device heat treatment is 50 times or less. A silicon single crystal wafer characterized by the above is provided.

As described above, the silicon single crystal wafer of the present invention is doped with nitrogen and the entire surface of the wafer is in the N region, and the non-defective rate of both the TZDB characteristic and the TDDB characteristic is 90% or more. The ratio of maximum and minimum BMD density (maximum value / minimum value) in the wafer surface after gettering heat treatment or device heat treatment is 50 times or less. There is no crystal defect and the oxide breakdown voltage characteristics are extremely excellent.Although it is in the N region, the variation in the BMD density in the wafer surface after gettering heat treatment or device heat treatment is small and uniform, and the wafer is deformed by heat treatment. This is a silicon single crystal wafer that can effectively prevent the above. Here, the non-defective product ratio of the TZDB characteristic and the TDDB characteristic is the cell formed in the wafer. In the following, this is simply expressed as the non-defective product rate for the TZDB and TDDB characteristics.

 [0017] Preferably, the silicon single crystal wafer has an oxygen concentration of 8 ppma or more and less than 13 ppma (JEI DA)! /.

 In this way, if the oxygen concentration is 8 ppma or higher, the BMD inside the wafer can be made sufficiently dense by heat treatment such as a device manufacturing process, and a silicon single crystal wafer having gettering capability is obtained. If it is less than 13 ppma (JEIDA), not only the TZDB characteristics but also the TDDB characteristics can be more than 90% acceptable.

At this time, it is desirable that the doped nitrogen concentration is 5 × 10 ^U atoms / cm ³ or more and 3 × 10 ¹³ atoms / cm ³ or less! /.

Thus, if the doped nitrogen concentration is 5 × 10 ^U atoms / cm ³ or more, the precipitation of oxygen is promoted in the heat treatment such as the device manufacturing process, and the BMD inside the wafer can be made to have a sufficient density. It is possible to make a silicon single crystal wafer with gettering capability, and if it is 3 X 10 ¹³ atoms / cm ³ or less, not only the TZDB characteristics but also the TDDB characteristics are more reliable. It can be over 90%.

Furthermore, it is preferable that the BMD density inside the wafer after the gettering heat treatment or device heat treatment is 1 × 10 ⁷ pieces / cm ³ or more.

Thus, if the BMD density inside the wafer after gettering heat treatment or device heat treatment is 1 × 10 ⁷ pieces / cm ³ or more, silicon having sufficient BMD density and high gettering ability It can be a single crystal wafer.

 [0020] Here, the gettering heat treatment is a general term for heat treatment performed after the grown silicon single crystal rod is added to the wafer and before entering the device process. This is a generic term for heat treatment performed in the device manufacturing process or simulation heat treatment that simplifies it regardless of the presence or absence of gettering heat treatment and other treatments.

 [0021] Further, in the silicon single crystal wafer, the oxygen precipitate on the surface layer of the wafer is heated by heat treatment, and the melting force is accelerated.

Nitrogen-doped crystals work with nitrogen force Vacancy to promote oxygen precipitation . For this reason, oxygen precipitate nuclei are formed during crystal growth, and oxygen precipitates may be formed depending on the conditions. When the wafer is cut out from the crystal, if this oxygen precipitate appears on the surface, the electrical characteristics may be degraded. For this reason, by applying heat treatment, oxygen precipitates on the surface layer can be dissolved and a wafer with higher quality can be obtained.

[0022] Further, according to the present invention, when a silicon single crystal is grown by the Tyoklalsky method, nitrogen having a concentration of 5 X 1 oHatoms / cm ³ or more and 3 X 10 ¹³ atoms / cm ³ or less, 8 ppma or more and ¹³ p pma Provided is a method for producing a silicon single crystal wafer, characterized in that it is pulled up under the condition that the entire crystal surface becomes an N-region while doping oxygen at a concentration of less than (JEIDA).

[0023] As described above, when growing a silicon single crystal by the Tioklalsky method, nitrogen having a concentration of 5 X 10 ^U at oms / cm ³ or more and 3 X 10 ¹³ atoms / cm ³ or less, and 8 ppma or more and less than 13 ppma The silicon single crystal wafer obtained from this silicon single crystal may have the above nitrogen concentration and oxygen concentration if it is pulled up under the condition that the entire surface of the crystal becomes N-region while doping oxygen at a concentration of (JEIDA). it can. As a result, a silicon single crystal wafer having a high density BMD inside the wafer and sufficient gettering ability after the gettering heat treatment and device heat treatment can be obtained. In addition, there is no crystal defects in the surface layer region. Excellent TZDB and TDDB characteristics. BMD density variation in the wafer surface is small and uniform, so a silicon single crystal wafer with reduced deformation is obtained. Is possible.

 Further, the silicon single crystal wafer obtained by the above method can be subjected to heat treatment at 1000 to 1300 ° C. for 10 seconds to 1 hour to dissolve oxygen precipitates on the surface layer of the wafer. By applying such heat treatment to the wafer and dissolving the oxygen precipitates on the wafer surface layer, it is possible to obtain a higher quality wafer that is less likely to deteriorate in electrical characteristics.

[0025] The heat treatment is preferably performed by a rapid heating / rapid cooling device.

In this way, the heat treatment is performed by a rapid heating / rapid cooling device (hereinafter, referred to as an RTA (Rapid Therma 1 Anneler) device) in a range of several to several hundred seconds of wafers (for example, several times from the wafer surface). nm to tens of nm) can be dissolved to a level where there is no problem with the oxide film breakdown voltage characteristics, so that a long-lasting thermal history with many harmful effects can be eliminated. It is possible to perform an effective heat treatment in a short time of several seconds to several hundred seconds without giving. As described above, the silicon single crystal wafer of the present invention and the silicon single crystal wafer manufacturing method have high quality with both excellent TZDB characteristics and TDDB characteristics, and the entire surface of the wafer is a device in the wafer surface region. Although it is an N-region that does not generate crystal defects that degrade device characteristics when present in the active layer, it is easy to generate BMD inside the device relatively uniformly, which can prevent metal contamination that occurs during device formation. It is possible to provide a silicon single crystal wafer that can be used. Brief Description of Drawings

 FIG. 1 is a conceptual diagram schematically showing a silicon single crystal wafer according to the present invention.

 FIG. 2 is a schematic view showing an example of a single crystal pulling apparatus that can be used in the method for producing a silicon single crystal wafer of the present invention.

 FIG. 3 is a schematic view showing an example of an RTA apparatus that can be used in the method for producing a silicon single crystal wafer of the present invention.

 FIG. 4 is a graph showing the results of nitrogen concentration, oxygen concentration, and TDDB characteristics in silicon single crystal wafers of examples, comparative examples, and reference examples.

 BEST MODE FOR CARRYING OUT THE INVENTION

[0028] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.

 In recent years, with the miniaturization of elements accompanying the high integration of semiconductor circuits, high quality has been required for the silicon single crystal wafer used as the substrate. Therefore, N-region crystals have been widely used as low-cost defect-free wafers.

However, in wafers cut from the entire N-region crystal obtained by the conventional method, oxygen precipitation is likely to occur on the V-rich side and oxygen precipitation occurs on the I-rich side even in the N-region where no defects are detected. This is characterized by the fact that the portion where oxygen precipitation is likely to occur and the portion where it is difficult to occur are mixed in the wafer surface, and the density of BMD observed after device heat treatment etc. varies greatly. . This variation in BMD leads to deformation of the wafer. [0029] Further, according to the conventional method, the margin for growing the entire N region crystal is narrow, and the product yield is lowered. Therefore, for example, the power proposed to dope nitrogen as disclosed in Japanese Patent Laid-Open No. 2000-53497 The present inventors investigated the silicon single crystal wafer obtained in Japanese Patent Laid-Open No. 2000-53497. However, we discovered that even if TZDB is good, TDDB failure may occur. If there is a defect in the TDDB, there may be problems with the latest state-of-the-art devices, which should be improved.

 [0030] In addition, Japanese Patent Application Laid-Open No. 2005-159028 discloses that a silicon wafer produced from a silicon single crystal grown by the CZ method is subjected to heat treatment. The entire wafer surface is an N region, and the wafer surface is The yield rate of the oxide film withstand voltage at least up to 5 m is 95% or more, and the ratio of the maximum and minimum BMD density inside the wafer (maximum / minimum) is Annie Rueno, characterized in that it is 1 to 10, and its production method are disclosed!

 [0031] However, the evaluation of the oxide film breakdown voltage characteristic in JP 2005-159028 A is only the TZDB characteristic, the TDDB characteristic is not evaluated, and the manufacturing method described in the examples Thus, the present inventors have found that the non-defective product ratio of the TDDB characteristic cannot satisfy 90%.

[0032] In addition, in Japanese Patent Application Laid-Open No. 11 195565, the CZ method is used, and the OSF ring is produced through a single crystal growth process under a low speed pulling condition that occurs inside the outer peripheral portion of the pulling crystal or disappears at the central portion. There is no description about the force S and TDDB characteristics that are disclosed for silicon wafers with a nitrogen concentration of 1 X 10 ¹³ atoms / cm ³ or more. In Japanese Patent Application Laid-Open No. 11-195565 and Japanese Patent Application Laid-Open No. 2005-159028, even if the TZDB characteristic is good, a defect may occur in the TDDB characteristic. There has been no.

[0033] Then, the present inventors have conducted extensive research on silicon single crystal wafers with respect to oxide film breakdown voltage characteristics, particularly TDDB characteristics, and as described above, as described above, the above-mentioned JP-A-2000-53497 The conventional methods such as JP 2005-159028 and JP 11-195565 only ensure wafers with excellent quality such that the non-defective product ratio of both TZDB characteristics and TDDB characteristics is 90% or more. Found that I can not get. In addition, if the maximum / minimum BMD density in the wafer plane is 50 times or less, the variation in BMD density is sufficiently suppressed, and deformation of the wafer during heat treatment etc. is suppressed, warping, etc. The present invention has been completed by discovering that it can be effectively prevented. The inventors of the present invention have found that the range of the oxygen concentration and the nitrogen concentration for doping the silicon single crystal wafer (silicon single crystal) is particularly important.

 [0034] Hereinafter, the power of describing the silicon single crystal wafer of the present invention in detail with reference to the drawings. The present invention is not limited to this.

 FIG. 1 schematically shows an example of the silicon single crystal wafer of the present invention. The silicon single crystal wafer 21 of the present invention shown in FIG. 1 is produced by slicing a silicon single crystal grown by the Tjoklarsky method. This silicon single crystal wafer 21 is nitrogen-doped, and the entire surface of the wafer is an N-region. Further, heat treatment is performed, and oxygen precipitates in the wafer surface layer region 22 are dissolved.

 The silicon single crystal wafer 21 of the present invention has a particularly high concentration of the doped nitrogen.

It is desirable that it is 3 X 10 ¹³ atoms / cm ³ or less. In this way, if the nitrogen concentration is 3 × 10 ¹³ at oms / cm ³ or less, the yield rate of both TZDB characteristics and TDDB characteristics can be more reliably 90% or higher, and extremely excellent oxidation Even if a device is fabricated in the wafer surface layer region 22, the device can be made to be a wafer without degrading the device characteristics.

[0036] The nitrogen concentration in the silicon single crystal wafer 21 is preferably 5 X 10 ^U atoms / cm ³ or more. By setting such a concentration range, after the gettering heat treatment or the device heat treatment, the BMD density becomes sufficient inside the wafer, and a silicon single crystal wafer having gettering ability can be obtained.

In particular, the BMD density inside the wafer can be 1 X 10 ⁷ pieces / cm ³ or more. A wafer having such a relatively high density BMD can be provided with higher gettering capability. The upper limit of the BMD density inside the wafer is not particularly limited as long as appropriate gettering capability is obtained.

Also, the oxygen concentration is desirably 8 ppma or more and less than 13 ppma (JEIDA), and as described above, it has sufficient BMD density and gettering ability after gettering heat treatment. In addition, the quality rate of both TZDB characteristics and TDDB characteristics is 90% or higher, and the quality is excellent.

Further, in the silicon single crystal wafer 21 of the present invention shown in FIG. 1, the ratio of the maximum density value to the minimum value in the wafer plane (maximum value) for BMD24 in the Balta region 23 after gettering heat treatment and device heat treatment (Value / minimum value) power ¾0 times or less! In other words, BMD24 is uniformly formed in the wafer plane, and the density variation of BMD24 is small. In particular, (maximum value / minimum value) may be 30 times or less. Therefore, an excellent silicon single crystal wafer having uniform gettering ability with small variations in the wafer plane in the Balta region can be obtained.

 Further, since the density distribution of the BMD 24 is uniform, deformation such as wafer warping caused by this density variation can be effectively prevented.

 Here, BMD should be measured by infrared tomography (LST) after heat treatment simulating the device process for a total of 20 hours centered at 800 ° C, for example, between 750 ° C and 950 ° C. I can do it. The measurement position at this time is, for example, an area of about 50 to 180 m from the surface, with a depth of about 10 mm from the edge to the center at 10 mm intervals.

In the present invention, the non-defective product ratio of the TZDB is, for example, an oxide film withstand voltage of room temperature under the condition of an oxide film thickness of 25 nm, a gate area of 8 mm ² , and a judgment current value of ImA / cm ^3. 8

Indicates the ratio of MV / cm or more.

The percentage of non-defective products of TDDB is, for example, the ratio of the gate oxide film thickness of 25 nm, the gate area of 4 mm, the stress current value of 0.01 A / cm ² , and the oxide film breakdown voltage of 5 C / cm ² or more at room temperature. Indicates.

[0039] If oxygen precipitates are present on the wafer surface layer, heat treatment may be applied to the wafer to dissolve the oxygen precipitates on the wafer surface layer.

 In this way, if the oxygen precipitates on the wafer surface are dissolved, the electrical properties are not deteriorated and a higher quality wafer can be obtained.

As described above, the silicon single crystal wafer 21 of the present invention shown in FIG.

22 has very few crystal defects and both TZDB and TDDB characteristics are excellent. In addition, after the gettering heat treatment and the device heat treatment, the BMD 24 having a sufficient and uniform density in the Balta region 23 is obtained. For this reason, uniform gettering ability can be provided within the wafer plane, and deformation such as warpage is very unlikely to occur in the wafer.

 [0041] The silicon single crystal wafer 21 of the present invention as described above can be obtained, for example, by a method for producing a silicon single crystal wafer of the present invention described later. Hereinafter, an example of the manufacturing method will be described in detail.

 First, a single crystal pulling apparatus that can be used when pulling a silicon single crystal by the CZ method in the method for manufacturing a silicon single crystal wafer of the present invention will be described.

 A single crystal pulling apparatus 18 shown in FIG. 2 includes a crucible 5 and 6 for containing a raw material melt 4, a heater 7 for heating and melting a polycrystalline silicon raw material, and the like provided in the main chamber 1. A pulling mechanism (not shown) for pulling up the grown single crystal is provided on the upper portion of the pulling chamber 2 continuously provided on the main chamber 1.

 A pulling wire 16 is unwound from a pulling mechanism attached to the upper part of the pulling chamber 2, and a seed holder and a seed crystal 17 are attached to the tip of the pulling wire 16. The single crystal rod 3 is formed under the seed crystal 17 by dipping in the liquid 4 and winding the bow I raising wire 16 by the pulling mechanism.

 The crucibles 5 and 6 are composed of a quartz crucible 5 on the inside and a graphite crucible 6 for supporting the quartz crucible 5 on the outside. These crucibles 5 and 6 are supported by a crucible rotating shaft that can be rotated and raised by a rotation drive mechanism (not shown) attached to the lower portion of the single crystal pulling device 18.

 Further, a heat insulating member 8 is provided outside the heater 7 disposed around the crucibles 5 and 6.

 In addition, a gas inlet 10 and a gas outlet 9 are provided in the chambers 1 and 2 so that argon gas or the like can be introduced into the chambers 1 and 2 and discharged.

[0044] The cooling cylinder 11 extends from at least the ceiling of the main chamber 1 toward the raw material melt surface so as to surround the single crystal rod 3 being pulled up. In this cooling cylinder 11, The cooling medium is introduced from the cooling medium inlet 12 to forcibly cool the cooling cylinder 11, and the single crystal rod 3 is cooled by blocking the radiant heat from the heater 7 between the vicinity of the melt surface and the cooling cylinder 11. In order to achieve this, a cooling auxiliary member 13 and a heat shield member 14 are provided. Furthermore, a protective cover 15 is provided to prevent the raw material melt 4 that may be scattered when the raw material melts from adhering to the cooling cylinder 11.

 [0045] Thus, the single crystal pulling apparatus that can be used in the production method of the present invention can be the same as the conventional one.

 A magnet (not shown) can be installed outside the main chamber 1 in the horizontal direction, so that a magnetic field in the horizontal direction or the vertical direction is applied to the raw material melt 4 to convect the raw material melt. This is a single crystal pulling device using the so-called MCZ method that suppresses and stabilizes the growth of single crystals.

 FIG. 3 shows an example of an apparatus that can rapidly heat and cool a silicon single crystal wafer obtained by slicing a silicon single crystal obtained by the single crystal pulling apparatus.

 The rapid heating / rapid cooling apparatus 32 shown in FIG. 3 has a chamber 33 made of quartz, and heats the silicon single crystal wafer 31 in the chamber 33. Heating is performed by a heating lamp 34 arranged so as to surround the chamber 33 from above, below, left and right. The heating lamps 34 can control the power supplied independently.

[0047] On the exhaust side of the gas, an auto shutter 35 is provided to seal off the outside air! The auto-shutter 35 is provided with a wafer inlet (not shown) configured to be opened and closed by a gate valve. The auto shutter 35 is provided with a gas exhaust port 30 so that the furnace atmosphere can be adjusted.

 The silicon single crystal wafer 31 is arranged on a three-point support portion 37 formed on the quartz tray 36. A quartz buffer 38 is provided on the gas inlet side of the tray 36 to prevent the introduced gas from directly hitting the silicon single crystal wafer 31.

The chamber 33 is provided with a temperature measurement special window (not shown), and a silicon single crystal is passed through the special window by a pie meter 39 installed outside the chamber 33. The temperature of wafer 31 can be measured.

 Thus, the RTA apparatus that can be used in the present invention can be the same as the conventional one.

 Hereinafter, an example of the procedure of the method for producing a silicon single crystal wafer according to the present invention will be described.

Yes

In the production method of the present invention, when a silicon single crystal is grown by the Tyoklalsky method, nitrogen having a concentration of 5 × 10 ^U atoms / cm ³ or more and 3 × 10 ¹³ atoms / cm ³ or less and 8 ppma or more and less than 13 ppma ( The following describes how to grow a silicon single crystal with the entire surface of the N region doped with oxygen with a concentration of JEIDA) and the condition that the entire surface of the crystal is in the N region. If such an entire surface N-region crystal can be grown, the cut wafer will be of the N region where the entire wafer surface is low-defects.

 As described above, it is necessary to control to a certain F / G to obtain the entire N-region crystal. However, it is difficult to expand the N region in the axial direction of the crystal even if the N-region is to be manufactured by expanding the entire crystal region, because the control range of the pulling speed that becomes the N region is narrow. Therefore, as in the present invention, by doping nitrogen, the N region can be expanded and the N region can be obtained easily and easily by controlling the growth conditions of the single crystal.

As described above, for example, using a single crystal pulling apparatus as shown in FIG. 2, it is possible to pull a silicon single crystal in which the entire crystal surface is an N region and is doped with nitrogen or oxygen. At this time, as described above, in the production method of the present invention, nitrogen is doped at a concentration of 5 × 10 ^u atom _S / _C m ³ or more and 3 × 10 ¹³ atoms / cm ³ or less, and oxygen is 8 ppma or more and less than 13 ppma ( Dope at a concentration of JEIDA).

 As a nitrogen doping method, for example, nitride is put in a quartz crucible in advance, the force for introducing nitride into the silicon melt, the atmosphere gas is an atmosphere containing nitrogen, etc., and the amount of nitride or nitrogen By adjusting the gas concentration or introduction time, the amount of doping in the crystal can be controlled, and doping can be performed within the above range.

Also, for example, by adjusting the rotation speed of the crystal when pulling up, the rotation speed of the crucible, the temperature distribution in the furnace, the gas pressure in the chamber, etc., the oxygen concentration in the silicon single crystal Can be doped within the above range.

 In this case, a magnetic field may be applied to the silicon melt when growing the crystal by the CZ method.

[0050] In this way, when gettering heat treatment or device heat treatment is applied to a wafer cut out from this silicon single crystal by doping nitrogen at a concentration of 5 X 10 ^u atoms / cm ³ or more, the inside of the wafer is The density of the formed BMD can be made 1 × 10 ⁷ pieces / cm ³ or more, and the power S can be used to produce a silicon single crystal as a wafer with sufficient gettering ability.

In addition, by doping nitrogen at a concentration of 3 X 10 ¹³ atoms / cm ³ or less, a silicon single crystal wafer having excellent oxide breakdown voltage characteristics in which the yield rate of both TZDB characteristics and TDDB characteristics is 90% or more, respectively. It can be.

[0051] Further, by setting the oxygen concentration to 8 ppma or more (JEIDA), the BMD density inside the wafer becomes 1 X 10 ⁷ pieces / cm ³ or more after gettering heat treatment, etc., and the gettering capability is sufficient. The silicon single crystal wafers that can be used as wafers can be obtained, and by making it less than 13 ppma (JEIDA), not only the TZDB characteristics but also the TDDB characteristics are excellent quality silicon with a yield rate of 90% or more. Ability to produce single crystal wafers with S.

[0052] Further, by pulling up the silicon single crystal in the above concentration range, a BMD density of 1 × 10 ⁷ pieces / cm ³ or more is obtained at any location in the wafer plane after the gettering heat treatment or the like. Therefore, it is possible to manufacture a silicon single crystal wafer whose ratio between the maximum value and the minimum value is 50 times or less, and further 30 times or less. As described above, since the variation in the BMD density in the wafer surface is extremely small, an excellent silicon single crystal wafer having uniform gettering ability can be obtained. It is possible to make a silicon single crystal wafer that can effectively prevent the occurrence of deformation.

Yes

[0053] Further, in the silicon single crystal wafer obtained as described above, for example, when oxygen precipitates are present on the surface layer of the crystal, heat treatment is performed at 1000 to 1300 ° C for 10 seconds to 1 hour. It is better to dissolve oxygen precipitates on the wafer surface layer. To do this Therefore, it is possible to prevent the effects of oxygen precipitates such as abnormal oxygen precipitation on the wafer surface, and to obtain wafers with very few crystal defects.

 In addition, since the wafer in the Balta region contains nitrogen, the precipitation of oxygen is promoted, and a wafer having sufficient gettering ability can be produced. At this time, the atmosphere for the heat treatment can prevent the surface of the wafer from being roughened if nitrogen and / or oxygen gas is contained in addition to argon and / or hydrogen gas.

 [0054] At this time, it is preferable to dissolve the oxygen precipitates in the extreme surface layer to a level that does not cause a problem in the oxide film pressure resistance characteristics, using an RTA apparatus as shown in FIG. If heat treatment is performed using an RTA device, heating and cooling in the heat treatment are performed in a few seconds to several hundred seconds, so a short time of several seconds to several hundred seconds that does not give the wafer a harmful long-term heat history. Effective heat treatment can be applied.

[0055] For example, using the RTA apparatus shown in FIG. 3, rapid heating is performed at a temperature rising rate of 5 ° C / sec or more in an argon and / or hydrogen atmosphere, and the desired temperature is about 1000 to 1300 ° C. ;! Holds for ~ 60 seconds, and then can be subjected to RTA treatment that rapidly cools at a temperature drop rate of 5 ° C / se _C or higher.

 By successively introducing the wafers into the furnace and continuously performing the heat treatment, it is possible to efficiently and effectively heat the wafers.

 At this time, nitrogen and / or oxygen gas is included! /, Which is more preferable because it can prevent roughing of the wafer surface.

[0056] In the silicon single crystal wafer and the method for producing a silicon single crystal wafer according to the present invention, the wafer diameter is not particularly limited. For example, a wafer having a large diameter of 200 mm or more, further 300 mm or more can be supported. Therefore, it is possible to meet the demand for larger diameters in recent years, and to obtain a silicon single crystal wafer having uniform in-plane characteristics.

[0057] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

(Example:! ~ 7) Using the single crystal pulling device shown in Fig. 2, a raw material polycrystalline silicon and a silicon wafer with a nitride film were charged into a quartz crucible with a diameter of 24 inches (60 cm), and a silicon single crystal with a diameter of 8 inches (200 mm) was pulled. The nitrogen concentration to be doped was controlled by the thickness of the nitride film. The crucible can be moved up and down in the direction of the crystal growth axis, and the crucible is raised to compensate for the lowering of the raw material melt that has decreased during crystal growth, while maintaining the height of the melt surface at a single crystal. Was raised.

 In addition, a horizontal magnetic field was applied to the raw material melt, and the rotation speed of the crucible was controlled at 0.01 -0.1 rpm to control the oxygen concentration. Furthermore, the entire N-region crystal was grown by changing the crystal pulling speed in the range of 0.56-0.60 mm / min.

 By appropriately adjusting the operating conditions as described above, the entire surface of the crystal becomes an N-region, and the nitrogen concentration and oxygen concentration doped in the silicon single crystal to be grown are controlled, so that the grown silicon single crystal is The silicon single crystal wafers of the present invention having different nitrogen and oxygen concentrations were obtained by slicing. Table 1 shows the oxygen concentration, nitrogen concentration, TDDB characteristics, and BMD test results described later (Examples;! To 7).

[table 1]

Oxygen Nitrogen T Z D B T D D B B M D B M D B M D

 Concentration Concentration Characteristic Characteristic (max) (min)

(ppma) (atoms / cm ³ ) (good product rate (good product rate (holiday / cm ³ ) (pieces / cm ³ )

 90% or more) 90% or more)

 Example 1 12.5 1.0E + 12 ○ ○ 24 3.5E + 08 1.5E + 07

 Example 2 10.5 4.2E + 12 ○ ○ 19 1.8E + 08 9.0E + 06

 Example 3 13.0 4.2E + 12 ○ ○ 2 1.6E + 09 7.0E + 08

 Example 4 8.9 1.0E + 13 ○ ○ 12 4.0E + 08 3.3E + 07

 Example 5 10.4 1.0E + 13 ○ ○ 5 4.3E + 08 9.6E + 07

 Example 6 12.2 1.1E + 13 ○ ○ <2 1.1E + 09 8.2E + 08

 Example 7 10.6 2.7E + 13 ○ ○ 4 6.3E + 08 1.5E + 08

 Comparative Example 1 15.5 1.1E + 13 ○ X <2 1.0E + 09 4.5E + 08

 Comparative Example 2 13.5 3.1E + 13 ○ X <2 1.6E + 09 9.5E + 08

 Comparative Example 3 12.5 3.3E + 13 X X 2 9.7E + 08 7.2E + 08

 Comparative Example 4 10.7 6.4E + 13 ○ X <2 1.1E + 09 8.2E + 08

 Comparative Example 5 12.8 6.4E + 13 ○ X <2 1.8E + 09 1.3E + 09

 Comparative Example 6 11.5 4.0E + 11 ○ ○> 500 1.0E + 08 <2.0E + 05

 Reference example 7.5 1.0E + 13 ○ ○ <2.0E + 05 <2.0E + 05

 Comparative Example 7 11.2 Non-dope ○ ○> 500 1.2E + 08 <2E + 05

 Comparative Example 8 12.4 Non-dope ○ ○ 73 1.7E + 08 2.3E + 06

 Comparative Example 9 10.3 Non-dope ○ ○> 500 1.3E + 08 <2E + 05

 Comparative Example 10 13.4 Non-dope ○ ○ 55 2.4E + 08 4.5E + 06

[0059] After the wafers of Examples 1 to 7 were subjected to non-stirring selective etching (removal allowance 25 Hm, Seco etching), the surface was observed with a microscope. As a result, the flow pattern called FPD observed when there is a void defect due to Vacancy and the etch pit observed when there is a transition cluster due to Interstitial-Si were not observed. In addition, this wafer was subjected to OSF formation heat treatment in a wetO atmosphere at 1150 ° C for 60 minutes,

 2

 When selective etching (removal allowance 7 m, NIT solution) was performed and the presence or absence of OSF was confirmed with a microscope, OSF was not observed.

 Thus, it can be seen that a silicon single crystal wafer having the entire N-region is obtained. Nitrogen doping made it easy to obtain wafers in the N-region with a wide range of pulling speeds that can be controlled.

[0060] Next, as a result of forming an oxide film having a thickness of 25 nm on the same wafer and investigating the electrical characteristics of this oxide film, the non-defective rate of both the TZDB characteristic and the TDDB characteristic was found in any of the wafers of the present invention. It was over 90%, and it was found that it had excellent oxide film pressure resistance characteristics Yes

 Figure 4 shows the results. In Fig. 4, the case where the non-defective product rate of the TDDB characteristic is less than 90% is indicated by X, and the case of 90% or more is indicated by.

[0061] Further, a similar wafer was subjected to a heat treatment simulating a device process. In other words, a total of 20 hours of heat treatment was performed between 750 ° C and 950 ° C, mainly at 800 ° C. After this heat treatment, the in-plane distribution of BMD was evaluated using an infrared scattering tomograph (M0441 manufactured by Mitsui Kinzoku). As a result, all wafers were able to achieve IX 10 ⁷ pieces / cm ³ over the entire surface of the wafer. In other words, we have the ability to make a wafer with sufficient gettering ability, the ability to be able to do S, and the half of the power.

 [0062] Furthermore, as shown in Table 1, it can be seen that the ratio between the maximum value and the minimum value of BMD is 50 times or less. As described above, since the silicon single crystal wafer has a uniform BMD density in the wafer plane, it can exhibit a uniform gettering ability in the plane, and the wafer has a non-uniform BMD density distribution. Use force S to effectively prevent warping.

[0063] (Comparative Example ;! to 6, Reference Example)

 A silicon single crystal wafer was obtained by pulling up and slicing a silicon single crystal in the same manner as in Example 1 except that the nitrogen concentration and oxygen concentration to be doped were changed as shown in Table 1 (Table 1, Comparative Example; ! ~ 6, reference example).

 At this time, the operating conditions were adjusted by the thickness of the nitride film (non-dope is 0) and the crucible rotation in the same manner as in the example so that the nitrogen concentration and oxygen concentration shown in Table 1 were obtained.

[0064] These wafers were examined for the presence of FPD, etch pits, and OSF in the same manner as in the Examples, but none were observed. This shows that a silicon single crystal wafer with the entire N-region was obtained.

[0065] For Comparative Examples 1 to 5, that is, when the oxygen concentration is 13 ppma or more, or the nitrogen concentration exceeds 3 X 10 ¹³ atoms / cm ³ , BMD is investigated in the same manner as in Example 1. As a result, a density of 1 × 10 ⁷ pieces / cm ³ was achieved over the entire surface of the wafer, and the maximum / minimum values were suppressed to 50 times or less. [0066] However, for the same wafer, the TZDB characteristics and TDDB characteristics were investigated in the same manner as in Example 1. As a result, the non-defective product ratio of the TZDB characteristics was 90% or more. S, TDDB characteristics Were found to be less than 90%. As described above, if there is a defect in the TDDB characteristics in this way, it will lead to a defect in the latest device.

[0067] On the other hand, in Comparative Example 6 where the nitrogen concentration is less than 5 X loHatoms / cm ³ , the minimum value of BMD is 2 X 10 ⁵ pieces / cm ³ or less, and the maximum value / minimum value is 500 times or more. It is becoming. Thus, if the BMD density distribution is non-uniform, warping or the like is likely to occur during heat treatment. In addition, the gettering ability becomes non-uniform in the wafer plane and the gettering ability is insufficient.

In the case of a reference example with an oxygen concentration of less than 8 ppma, the maximum / minimum value of BMD is 2 × 10 ⁵ pieces / cm ³ or less, and the BMD density is extremely low. I'll end up.

 The non-defective product ratio for the TZDB and TDDB characteristics was both over 90%.

[0068] (Comparative Examples 7 to 10)

 The silicon single crystal was pulled and sliced in the same manner as in Example 1 except that nitrogen was not doped and the oxygen concentration was changed as shown in Table 1. Examples 7-; 10). The nitrogen concentration at this time was below the detection limit.

 [0069] These wafers were examined for the presence of FPD, etch pits, and OSF in the same manner as in the Examples, but none were observed. This shows that a silicon single crystal wafer with the entire N-region was obtained.

[0070] BMD was investigated in the same manner as in Example 1. Although 1 X 10 ⁷ pieces / cm ³ was partially achieved in the wafer plane, this was achieved over the entire wafer area. There was no UA-8. Therefore, the lack of gettering ability was clearly caused. And the maximum / minimum value of BMD density is 50 times or more, and the gettering ability becomes non-uniform in the wafer plane. Also warp by heat treatment etc. Is likely to occur!

 The non-defective product ratio for the TZDB and TDDB characteristics was both over 90%.

[Example 8]

 A silicon single crystal wafer was produced in the same manner as in Example 1, and the wafer was subjected to heat treatment using the RTA apparatus shown in FIG. 3 to dissolve oxygen precipitates on the wafer surface layer, and in the wafer. BMD was formed to provide gettering ability.

 The heat treatment conditions were rapid heating and rapid cooling heat treatment at 1200 ° C for 10 seconds in a mixed atmosphere of argon and hydrogen.

[0072] This silicon single crystal wafer was tested in the same manner as in Example 1. As a result, FPD, etch pits, and OSF were not observed on the wafer surface layer. It was found that a sufficient defect-free layer without abnormal oxygen precipitation was obtained. In addition, an excellent silicon single crystal wafer having a sufficient gettering capability was obtained because BMD was uniformly formed in the inside at 1 × 10 ⁷ pieces / cm ³ or more. The wafer was not deformed such as warp even after the heat treatment.

 [0073] Examples 1 to 8 for a silicon single crystal wafer having a diameter of 200 mm as described above, comparative examples;! To 10, experiments similar to those in the reference example were conducted for a silicon single crystal wafer having a diameter of 300 mm. In both examples and comparative examples, almost the same results were obtained as when the diameter was 200 mm.

[0074] From the results of the above Examples and Comparative Examples, as shown in FIG. 4, the nitrogen concentration is 5 X 10 ^u atom _S / cm ³ or more and 3 X 10 ¹³ atoms / cm ³ or less, and the oxygen concentration is 8 ppma or more and 13 ppma. It can be seen that the non-defective rate of TZDB and TDDB characteristics is 90% or more by setting the ratio to less than (JEI DA).

Note that the present invention is not limited to the above-described embodiment. The above embodiment is merely an example, and has any configuration that is substantially the same as the technical idea described in the claims of the present invention and that exhibits the same operational effects. Also technical of the present invention Included in the range.

Claims

The scope of the claims  [1] Silicon single crystal wafer grown by the Chiyoklarsky method, doped with nitrogen, and entirely in the N-region, with good product ratio of TZDB and TDDB characteristics over 90% A silicon single crystal characterized in that the ratio (maximum value / minimum value) between the maximum value and the minimum value of the BMD density in the wafer plane after gettering heat treatment or device heat treatment is 50 times or less. Ueha. 2. The silicon single crystal wafer according to claim 1, wherein the silicon single crystal wafer has an oxygen concentration of 8 ppma or more and less than 13 ppma (JEIDA). [3] The silicon single crystal according to claim 1 or 2, wherein the doped nitrogen concentration is 5 X 10 ^U atoms / cm ³ or more and 3 X 10 ¹³ atoms / cm ³ or less. Crystal [4] The BMD density in the wafer after the gettering heat treatment or device heat treatment is 1 × 10 ⁷ pieces / cm ³ or more. The silicon single crystal wafer according to the item. [5] A silicon single crystal wafer according to any one of claims 1 to 4 of claim 1 to claim 4, wherein oxygen precipitates on the surface layer of the wafer are dissolved by heat treatment. Silicon single crystal wafer. [6] When growing a silicon single crystal by the Chiyoklarsky method, nitrogen with a concentration of 5 X 10 ^U atoms / cm ³ or more and 3 X 10 ¹³ atoms / cm ³ or less and 8 ppma or more and less than 13 ppma (JEID A) A method for producing a silicon single crystal wafer, characterized in that the entire surface of the crystal is pulled into an N-region while doping oxygen at a concentration. [7] The silicon single crystal wafer obtained by the method of claim 6 is 1000 to 1300 ° C, 10 A method for producing a silicon single crystal wafer, wherein a heat treatment for 1 to 1 hour is applied to dissolve oxygen precipitates on the surface layer of the wafer.  8. The method for producing a silicon single crystal wafer according to claim 7, wherein the heat treatment is performed by a rapid heating / cooling apparatus.