WO2001081661A1

WO2001081661A1 - Silicon single-crystal wafer, method for producing silicon single crystal, and method for fabricating silicon single-crystal wafer

Info

Publication number: WO2001081661A1
Application number: PCT/JP2001/003317
Authority: WO
Inventors: Izumi Fusegawa; Hiromi Watanabe; Shigemaru Maeda
Original assignee: Shin-Etsu Handotai Co.,Ltd.
Priority date: 2000-04-25
Filing date: 2001-04-18
Publication date: 2001-11-01
Also published as: JP4096557B2

Abstract

A CZ silicon single-crystal wafer having an Fe concentration of 1x1010 atoms/cm3 or less, a silicon single-crystal wafer produced from a silicon single crystal grown by the CZ method by using a flow straitening tube and having an Fe concentration of 1x1010 atoms/cm3 or less, and a CZ method for producing a silicon single crystal by growing a silicon single crystal disposed in a flow straitening tube on which a film having an Fe concentration of 0.05 ppm or less is formed are disclosed. A substrate for producing a semiconductor integrated circuit device the characteristics of which do not deteriorate from even the outermost part of a wafer with high yield.

Description

Description Silicon single crystal wafer and method for producing silicon single crystal

And manufacturing method of silicon single crystal wafer

The present invention relates to a high-quality silicon single crystal wafer manufactured by the CZ method (Chiyoklarsky method) used for manufacturing a semiconductor device, and a method for manufacturing the same. More specifically, a silicon wafer manufactured from a single crystal grown by the CZ method, and the uniformity of the electrical characteristics, in which the concentration of heavy metal impurities, particularly the Fe (iron) concentration, has been reduced to the outermost region of the wafer. The present invention relates to extremely high quality silicon wafers and a method for producing the same. Background art

In recent years, high integration of semiconductor integrated circuit devices and accompanying miniaturization have been remarkable, and there is a strong demand for large-diameter wafers and high-quality silicon wafers in order to improve the yield of device manufacturing. Among these requirements, items related to quality can be divided into items related to the shape of A-E8 and items related to the crystal quality of silicon single crystals. Items related to e-shape, such as surface flatness and warpage, are strongly related to the device manufacturing process, such as wiring pattern formation in the photolithography process and adsorption to the stage in the etching and film formation process.

On the other hand, items related to crystal quality, such as substrate oxygen concentration and heavy metal impurities, affect the characteristics of semiconductor integrated circuit devices (Ultra Clean Technology, Vol. 5 NO5 / 6 "Heavy Metal Contamination and Oxide Film of Silicon wafers. Flaw "). In particular, deterioration of the MOS gate oxide withstand voltage due to heavy metal contamination such as Fe has been reported and is a serious problem. In addition, the chip size of a highly integrated semiconductor integrated circuit device in recent years increases the number of bits, so the area required for one chip increases, and it can be obtained from silicon wafers with the same crystal diameter. The number of elements decreases (Applied Physics, Vol. 65 No. 11, 1996, "DR in the Gigabit Era" AM technology ").

On the other hand, to improve the yield, silicon single crystal with a diameter of 30 Omm or an alternative method of manufacturing the semiconductor integrated circuit device from the outermost peripheral area of the wafer, even though the diameter of the wafer is the same. A plan has been proposed. In the case where a large-diameter wafer is used, the area of the periphery of the wafer becomes particularly large, so that the effect of improving the yield in the peripheral area of the wafer becomes high. On the other hand, such a large-diameter wafer requires a silicon wafer having high uniformity up to the outermost peripheral region of the wafer, which has not been a problem in the past.

For the production of silicon single crystals used in the production of such semiconductor integrated circuit devices, the CZ method of growing and pulling single crystals from a melt in a quartz crucible is widely used. As is well known, in the CZ method, a seed crystal is immersed in a silicon melt in a quartz crucible under an inert gas atmosphere, and the quartz crucible and the seed crystal are slowly pulled up while rotating. This is to produce a con single crystal.

In such a CZ method, a quartz crucible is used, so that the silicon melt reacts with the quartz and oxygen atoms are eluted in the silicon melt, and a part of the oxygen atoms elutes into the growing silicon single crystal. Incorporated to provide an effect of improving mechanical strength and to be a gettering source for heavy metal impurities mixed in during the manufacture of semiconductor integrated circuit devices. On the other hand, most of the oxygen atoms evaporate from the melt surface as silicon oxides, and some of them adhere to components in the pulling furnace. If such deposits fall onto the surface of the silicon melt, they adhere to the growing silicon single crystal, causing dislocation troubles, and significantly lower the yield of the single crystal product.

For this reason, the growth of large silicon single crystals in recent years requires the drawbacks described in, for example, Japanese Patent Application Laid-Open No. 3-97688 / Japanese Patent Application Laid-Open No. Hei 6-219886. A rectifying cylinder is often used to rectify the inert gas introduced into the upper furnace and efficiently discharge such oxides from the silicon melt.

Here, the rectifying cylinder referred to in the present invention is an inert gas that is disposed so as to surround a silicon single crystal grown on the silicon melt surface in the CZ method and is introduced from the upper part of the chamber of the CZ device. A substance that acts to regulate the flow of gas. Therefore, the rectifying cylinder referred to here is a member arranged close to the grown crystal having the above function. The term is used as a generic term, and does not imply any particular language or name. Includes heat shields, heat insulators, etc., which are placed close to the crystal. In particular, when the diameter of the silicon single crystal to be grown becomes large, the speed at which the crystal is pulled must be reduced, the silicon melt becomes large, and the oxygen supply increases due to the increase in the size of the quartz crucible. Since the amount of oxides increases, dislocation troubles in the silicon single crystal are likely to occur. Therefore, in order to produce a silicon single crystal with a large diameter of 200 mm or more at a high yield, it is necessary to arrange a rectifying cylinder in the CZ device. On the other hand, one of the quality evaluations of silicon wafers is the lifetime of a minority carrier. This carrier lifetime indicates the time it takes for electron-hole pairs generated when high-energy pulsed light is incident on the silicon surface to return to the original thermal equilibrium state by recombination. Yes, heavy metals and crystal defects in the wafer become recombination centers for a small number of carriers, which significantly reduces the life time. Therefore, if heavy metal contamination occurs in the silicon single crystal, the lifetime of the minority carrier is greatly affected, and the characteristics of the semiconductor integrated circuit device formed on the wafer may be problematic.

However, this reduction in carrier lifetime was particularly noticeable in the outer periphery of large diameter silicon wafers made from large silicon single crystals. Investigations were conducted on silicon wafers where such a decrease in carrier lifetime was observed, and Fe contamination was detected in the vicinity of these silicon single crystals and wafers. Suspected of Fe contamination. When such a reduction in the lifetime occurs, the uniformity in the wafer surface is deteriorated, and there is a problem that the yield is reduced. Disclosure of the invention

The present invention has been made in view of the above points, and it is an object of the present invention to provide a substrate for manufacturing a semiconductor integrated circuit element capable of obtaining a high yield without deterioration in characteristics even at the outermost periphery of the wafer. Furthermore, even in the case of producing large-diameter crystals, it is possible to reduce the heavy metal contamination around the wafer to the utmost and to provide an industrially efficient method for producing silicon single crystals by using a rectifying cylinder with moderate purity. It is in. The present invention for solving the above problems is directed to a silicon single crystal wafer produced from a silicon single crystal grown by a CZ method, wherein the silicon single crystal wafer has an Fe concentration of 1 XIO ^ atoms / A silicon single crystal wafer having a size of not more than cm ³ .

As described above, even if the silicon single crystal grown by the CZ method has a Fe concentration of 1 XIO i Q atoms / cm ³ or less, the silicon single crystal grown with the carrier has a carrier as described above. Silicon single crystal wafers that are unlikely to cause problems such as a reduction in lifetime can be used. Furthermore, if the CZ wafer is used, it is easy to increase the diameter of the wafer, the yield of semiconductor elements obtained from the outer periphery thereof is also improved, and the overall yield of semiconductor manufacturing can be improved.

The present invention is also directed to a silicon single crystal wafer manufactured from a silicon single crystal grown by the cZ method, wherein the carrier lifetime variation width over the entire surface of the silicon single crystal wafer is set to (maximum value). (Single minimum value) A silicon single crystal wafer, characterized in that the fluctuation range when expressed by the Z maximum value is 50% or less.

As described above, the silicon single crystal silicon wafer having a small variation in carrier lifetime over the entire surface of the silicon wafer can have a small variation in electrical characteristics of a semiconductor device manufactured on the surface layer of the silicon wafer. In particular, such a wafer is particularly advantageous when a device is formed on a large-diameter wafer because the carrier lifetime in the periphery of the wafer can be kept small.

Further, the present invention relates to a silicon single crystal wafer manufactured from a silicon single crystal grown by the cZ method, wherein an e concentration of 10% around the silicon single crystal wafer is 1 XI 0 This is a silicon single crystal wafer having a density of ¹⁰ atoms Z cm ³ or less.

As described above, a silicon single crystal wafer having a Fe concentration of 10% or less around the silicon single crystal wafer at 1 × ^{10 10} atoms Z cm ³ or less has a large diameter even if the wafer has a large diameter. In addition, the carrier lifetime in the peripheral portion is hardly reduced, and the yield of device fabrication can be improved.

Here, 10% around the eha is the distance from the outermost periphery of the eha to the It means the outer edge within 10% in diameter. For example, in the case of a wafer having a diameter of 200 mm and 8 inches, this means an outer edge portion within a range of 2 O mm from the outermost periphery of the wafer. In this case, in the present invention, the diameter can be 20 O mm or more. As described above, if the diameter of the silicon single crystal wafer is 200 mm or more, the area of the wafer outer peripheral area becomes larger, and the yield improving effect of the wafer outer peripheral area is high. Becomes Especially Siri Konueha large diameter Runode be frequently is F _e contamination in the outer peripheral portion, as in the silicon single crystal Ueha of the present invention, a small F e concentration of F e concentration variations and Kiyari § lifetime If there is little variation, the yield of semiconductor device fabrication can be greatly improved.

Further, the silicon single crystal wafer of the present invention is a silicon single crystal wafer manufactured from a silicon single crystal grown using a rectifying tube in the cZ method.ゥ It is Eha.

As described above, according to the present invention, even if a silicon single crystal wafer is produced from a silicon single crystal grown using a rectifying tube in the CZ method, the Fe concentration in the wafer is reduced to 1 × 1 It can be set to 0 ¹⁰ atoms Z cm ³ or less. Therefore, even if a silicon single crystal has a large diameter, it can be easily manufactured at a high yield by using a straightening cylinder to prevent dislocations and the like, and it must be free from Fe contamination. it can. Further, the present invention provides a method for producing a silicon single crystal in which a silicon single crystal is grown while surrounding the silicon single crystal with a rectifying cylinder in the CZ method, wherein the Fe concentration on the surface is 0.05 ppm or less. A method for producing a silicon single crystal, characterized in that a silicon single crystal is grown using a rectifying cylinder having a film formed thereon.

In the method of manufacturing a silicon single crystal using a rectifying cylinder as described above, it is possible to grow a silicon single crystal using a rectifying cylinder having a film with a Fe concentration of 0.05 ppm or less formed on the surface. In addition, it is possible to reliably prevent the occurrence of Fe contamination in the single crystal grown from the flow straightening tube, and to improve the quality and yield of large-diameter silicon single crystal production in particular.

The film applied to the flow straightening cylinder can sufficiently exhibit its effect even if the coating is applied only to the inner surface of the flow straightening cylinder facing the grown crystal, or the coating can be applied to the entire flow straightening cylinder. These options depend on the method and cost of coating on the flow straightening tube, or the furnace internal structure. It should be selected variously for reasons such as the design of the product.

In this case, the film is preferably made of pyrolytic carbon or silicon carbide. If the film is made of pyrolytic carbon or silicon carbide in this way, the Fe concentration on the surface of the flow regulating cylinder can be easily kept low, and high purity can be maintained.

In this case, the thickness of the film is preferably 30 // m or more.

As described above, when the film thickness is 30 / zm or more, the volatilization of heavy metals such as Fe from the surface of the rectifying cylinder can be sufficiently prevented, and the film is sufficiently resistant to long-time use at high temperatures. It becomes something that can be obtained.

If a silicon single crystal wafer is manufactured from the silicon single crystal of the present invention, a silicon single crystal wafer with a small carrier lifetime variation over the entire surface of the wafer even with a large diameter can be easily manufactured. be able to.

The present invention also provides a flow regulating cylinder arranged so as to surround a silicon single crystal grown in the CZ method, and for regulating the flow of an inert gas introduced from the top of the chamber of the cZ apparatus. The rectifying cylinder is characterized in that a film with an Fe concentration of 0.05 ppm or less is formed on the rectifying cylinder.

Such a flow straightening tube surely prevents Fe contamination from occurring in a single crystal grown from the flow straightening tube, and can improve the quality and yield particularly in the production of large-diameter silicon single crystals.

In this case, the thickness of the film is preferably 30 / m or more.

As described above, when the film thickness is 30 μιη or more, it is possible to sufficiently prevent the volatilization of heavy metals such as Fe from the surface of the rectifying cylinder, and to sufficiently withstand long-time use at high temperatures. It becomes something that can be obtained.

The apparatus for producing a silicon single crystal having the rectifying cylinder of the present invention can reliably prevent Fe contamination from occurring in the single crystal grown from the rectifying cylinder. Can be manufactured with high productivity.

As is apparent from the above, according to the present invention, a rectifying cylinder used for growing a silicon single crystal. Since a high-purity film is formed on the surface of the silicon single crystal, heavy metal impurities do not adhere to the surface of the silicon single crystal since vapor containing heavy metal generated from the rectifying tube during the growth of the single crystal is not generated. Even at high temperatures, heavy metal impurities do not diffuse into the crystal, so that heavy metal contamination, especially in the peripheral area, is reduced to the utmost. By using a silicon wafer manufactured from the silicon single crystal according to the present invention at the time of manufacturing a semiconductor device, high purity can be maintained up to the outermost peripheral region of the wafer, thereby improving the manufacturing yield of the semiconductor integrated circuit device. BRIEF DESCRIPTION OF THE FIGURES

(A) to (H) in Fig. 1 show that a silicon single crystal is grown using a rectifying cylinder coated with pyrolytic carbon with different Fe concentrations, and that single crystal is processed into wafers, and the SPV method is used. FIG. 4 is a diagram showing the in-plane distribution of the Fe concentration when the in-plane Fe concentration is measured.

Figure 2 shows that a silicon single crystal was grown using a rectifying cylinder made of silicon carbide film, the single crystal was processed into wafers, and the in-plane Fe concentration was measured by the SPV method. FIG. 4 is a diagram showing a concentration in-plane distribution of the present invention.

Fig. 3 shows the results when a silicon single crystal was grown using a rectifying cylinder with no coating, the single crystal was processed into a wafer, and the in-plane Fe concentration was measured by the SPV method. FIG. 4 is a diagram showing the in-plane distribution of the Fe concentration of FIG.

Figure 4 is a diagram showing the outline of a crystal pulling device equipped with a flow straightening tube. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in more detail.

The present inventors have found that the life time varies in the plane of the eaves, and that the life time in the peripheral area is lower than that in the vicinity of the center of the eaves, and that a certain regularity is observed. As a result of repeated experimental studies, it was found that the cause of the decrease in the lifetime was due to impurities present in the ewa, especially Fe contamination. Then, the present inventors observed a pattern of Fe contamination appearing on the silicon wafer surface in an outer peripheral region of about 20 to 30 mm from the periphery. Heavy metal impurities mixed in due to segregation Heavy metal vapor, including Fe, generated from a rectifying tube placed outside the silicon single crystal to be grown, instead of being taken into the silicon single crystal, adheres to the growing crystal surface, and the crystal grows. It was assumed that the metal was diffused inside the crystal during the process of cooling from high temperature to room temperature and was contaminated.

This is because, when impurities actually mixed into the silicon melt are mixed into the crystal due to segregation, micro impurities due to growth fringes formed due to a difference in solidification rate due to non-uniformity of the melt temperature. A region with a high impurity concentration is observed locally due to concentration unevenness or facet growth. However, it has been confirmed that the impurity is almost uniformly mixed in the entire wafer (silicon, pp 120- 139, 1994, "Crystal growth and エー a processing", Baifukan). Therefore, if impurity contamination from silicon melt is considered to be the cause, it is not possible to explain the Fe-contaminated region that appears only in the periphery of the wafer or the decrease in the lifetime of minority carriers in the periphery.

Therefore, the present inventors conducted the following experiment to confirm this assumption. (Experiment 1)

Figure 3 is an in-plane Fe concentration map showing an example of measurement of in-plane Fe contamination of silicon wafers produced from crystals grown by the conventional silicon single crystal growth method. The crystal is grown by the silicon single crystal manufacturing apparatus 11 shown in FIG. 4, and this apparatus 11 includes a rectifying cylinder 4 made of a graphite material. Using this apparatus 11, 120 kg of polysilicon was charged into a quartz crucible 5 having a diameter of 56 cm to dissolve the polycrystal, and then a seed crystal having a (001) plane was melted. Then, a boron-doped silicon single crystal 3 having a diameter of 200 mm and a specific resistance adjusted to 10 Ω · cm was grown through a drawing step. A silicon single crystal wafer was produced through various processes necessary for industrial production of ordinary silicon wafers, such as cylindrical polishing, slicing, lapping, and polishing of the grown silicon single crystal. .

(4) The Fe concentration measurement of the wafer was performed by the SPV method (Surface Photovoltage Method). In other words, Fe dissolved in a boron-doped silicon single crystal is combined with boron as a dopant at room temperature and stabilized in the form of Fe_B (iron-boron pair). The binding energy of F e — B is about 0.68 eV, 200 ° C Most dissociate to the extent that Fei (interstitial iron atom) is formed. Since Fei forms a deep level, it acts as a recombination center for minority carriers and reduces the diffusion length of minority carriers. That is, the diffusion length of minority carriers was long before the heat treatment at about 200 ° C, but the diffusion length of minority carriers becomes short after the heat treatment because Fei acts as a recombination center. Therefore, in the SPV method, the Fe concentration can be measured by measuring the difference. In addition, the measurement results of the Fe concentration by the SPV method can also estimate the carrier life time variation that is proportional to the carrier diffusion length in principle (Analysis Handbook for ULSI Manufacturing, p. 386- 1991, 1991, "SPV method").

As an example of the SPV measurement result, as shown in Fig. 3, Fe contamination was remarkably measured in the area of 20 to 30 mm from the periphery of the e-wafer, which sometimes caused a problem. . The lowest Fe concentration around the periphery of the A-A-H8 is due to the problem of the measurement area by the SPV method. Fig. 3 shows that the Fe concentration is higher in the periphery as a whole, and the contamination is not due to contamination from silicon melt but to contamination due to diffusion of Fe from the crystal surface toward the center during single crystal growth. It is believed that there is.

Also, considering the temperature dependence of the diffusion coefficient of Fe in silicon, the thermal history calculated from the crystal growth rate (about lmm min) The calculated diffusion distance is about 24 mm. On the other hand, the experimental results showed that the diffusion distance of Fe was 20.5 mm, which was almost the same as the calculated value. In other words, it supports the observation that Fe contamination generated around the wafer is not the effect of Fe impurities mixed into the silicon melt but the diffusion of Fe impurities attached to the crystal surface during crystal growth. is there.

In order to prevent such contamination due to the diffusion of Fe impurities, some countermeasures are required during the production of silicon single crystals, especially in the high temperature range of 800 ° C or higher. In order to solve the above problems, the present inventors have conceived of covering a rectifying cylinder arranged around a silicon single crystal grown at the time of manufacturing a silicon single crystal with a high-purity film. In other words, even in a high temperature state during single crystal growth, such a rectifying tube does not generate heavy metal impurity vapors including Fe, and therefore, a silicon single crystal of high contamination and uniformity up to the outermost periphery of the wafer. It was thought that training was possible. Therefore, the present inventors conducted the following experiment on the relationship between the effect of providing a film on the surface of the flow control cylinder and the purity of the film.

(Experiment 2)

Each single crystal was grown by a crystal pulling device equipped with a rectifying cylinder made of graphite material with a pyrolytic carbon film of different purity formed on the surface, and each wafer was manufactured from the grown silicon single crystal. The state of Fe contamination was measured by the SPV method. The layer thickness of the pyrolytic carbon film formed on the rectifying cylinder is 40 / m, and the Fe concentration of the film is 0.01, 0.03, 0.05, 0.10, 0.1. Eight types of 5, 0.20, 0.25 and 0.30 ppm were used. Except for using such a covered flow straightening tube, the procedure was the same as in Experiment 1, and the confirmation and evaluation of Fe contamination by the SPV method was also performed in the same manner as in Experiment 1. -The Fe concentration of the film was measured by using an ICP (InducuttilyeCoupledP1asma) emission spectrometry.

The results are shown in Figure 1. Fig. 1 (A) to (C) With regard to the e-aperator manufactured using a rectifier with a Fe concentration of 0.05 ppm or less from the force, no Fe contamination around the e-aer was observed. Despite the use of a flow straightening tube, no Fe contamination was detected up to the periphery of the wafer, and a high-quality silicon single crystal wafer was obtained. On the other hand, from Figs. 1 (D) to (H), it can be seen from Fig. 1 that, for the e-chamber manufactured using a rectifying cylinder with an Fe concentration of more than 0.05 ppm, the Fe Contamination was scattered.

In other words, by forming a film of high-purity pyrolytic carbon having an Fe concentration of 0.05 ppm or less on the rectifying cylinder, Fe can be collected from the rectifying cylinder that is heated to a high temperature during the production of a silicon single crystal. Since no vapor-containing vapor was generated or the amount of generated vapor was slight, there was no Fe contamination on the surface of the silicon single crystal being grown, and there was no diffusion of Fe into the crystal. It is thought that a silicon single crystal wafer without contamination can be obtained. As described above, it was confirmed that the manufacturing method of the present invention can reduce Fe contamination of the silicon wafer which adversely affects the manufacture of the semiconductor integrated circuit device.

Hereinafter, the present invention will be described in more detail, but the present invention is not limited thereto. Absent.

The shape of the rectifying cylinder used in the present invention is not particularly specified. For example, in addition to the conventional type described in Japanese Patent Application Laid-Open No. Hei 6-219896, any form can be used as long as it is arranged close to and surrounding the growing crystal. The present invention can be applied to any of them.

However, a carbon material such as a graphite member is used as a general rectifying cylinder, and a distance in a range of 100 mm to 200 mm from the crystal, and a distance of 10 to 100 mm in proximity to the crystal. It is arranged so that it may touch. In addition, as a material of the rectifying cylinder, a high melting point metal such as tungsten or molybdenum can be used. Further, when an appropriate refrigerant is used, stainless steel or copper can be used as a material for the flow regulating cylinder.

It should be noted that the same effect can be obtained even when the high-purity coating material of the rectifying cylinder is a pyrolytic carbon film as described above or a silicon carbide film. The thickness of the film is preferably 30 μm or more. This is because if the thickness of the film is less than 10 μm, the film may be deteriorated by pulling the silicon single crystal several times, and it may not be possible to completely prevent heavy metal contamination. .

However, on the other hand, making the film too thick is not preferable in consideration of the production cost and productivity of the flow straightening tube, and cracks may easily occur when the film thickness is large. Practically, the film thickness is preferably at most about 200 / m, and it is preferable to select the film thickness of the rectifying cylinder film according to the conditions within this range.

It is known that a carbon material is used as the material of the rectifying cylinder, but it is considered that the same effect as that of the present invention can be obtained even when the material itself is highly purified. However, since the purification of the carbon material is performed by exposing the compact to a halogen gas atmosphere at a high temperature, a very long treatment is required. Since it becomes extremely expensive, it is preferable to provide the high-purity film.

In the case of forming a film made of pyrolytic carbon on a rectifying cylinder, for example, a raw material gas such as a mixed gas of C ₃ H ₈ and H ₂ is used for a conventional base material having sufficient heat resistance. A pyrolytic carbon film is formed by CVD (Chemica 1 Vapor Deposition) method. In this case, the purity of the film is The concentration should be less than 0.05 ppm. Such a purity can be achieved by increasing the purity of the raw material gas, so that it is easier than increasing the purity of the carbon substrate itself. According to the method of the present invention, since the setting of the purity only needs to be paid when the rectifying tube is manufactured, the cost is not so much higher than the conventional method using the rectifying tube.

As described above, the film formed on the rectifying cylinder may be silicon carbide. Silicon carbide has the advantage of excellent mechanical strength, heat resistance and corrosion resistance.

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

(Example 1)

α

A silicon wafer was manufactured from a silicon single crystal grown by a crystal pulling device equipped with a rectifying cylinder with a pyrolytic carbon film. The crystal pulling apparatus is the same as the existing crystal pulling apparatus shown in FIG. 4 except that the flow straightening tube used in the pulling method of the present invention is provided.

6

Performed.

O size

Here, in Example 1, the rectifying cylinder 4 used was a main body made of a graphite material on which a pyrolytic carbon film was formed by a CVD method. The size of the flow straightening cylinder 4 was 25 mm in inner diameter so that the gap between the crystal and the flow straightening cylinder was 25 mm. The layer thickness of the pyrolytic carbon film covering the flow straightening tube was set to 40 m, and the Fe concentration was set to 0.05 ppm or less when forming the film. The purity of the film formed on the rectifier tube was measured by the above-mentioned ICP emission spectrometry, and the result was as shown in Table 1 below. From this, it can be seen that the Fe concentration of the pyrolytic carbon film formed on the surface of the rectifying cylinder of Example 1 is 0.05 ppm or less.

(table 1 )

Film composition Impurity concentration

B Fe AI N i Cr Na

Example 1 Pyrolytic carbon 0.03 0.03 0.03 0.1 4 0.74 0.05

Example 2 Silicon Carbide 0.12 0.01 0.01 0.02 0.07

Comparative example Pyrolytic carbon 0.009 0.10 0.009 0.444 1.98 0.16 Using the single crystal pulling apparatus described above, 120 kg of polysilicon is charged into a quartz crucible having a diameter of 56 cm to dissolve the polycrystal, and then a seed crystal having a (001) plane is converted into silicon melt. A boron-doped silicon single crystal having a specific resistance of 200 Ω · cm and a diameter of 200 mm was grown through a immersion process and a drawing process. Silicon single crystal wafers were produced through various processes necessary for industrial production of ordinary silicon wafers, such as cylindrical polishing, slicing, lapping, and polishing of the grown silicon single crystals.

The Fe contamination of the manufactured silicon single crystal wafer was evaluated by the SPV method described above. The results are shown in FIG. 1 (B). From Fig. 1 (B), no Fe contamination around the wafer was observed, and it was found that the Fe concentration from the center to the outer edge of the wafer was less than 1 XI 0 ¹⁰ & toms / cm ^3. Was. The Fe concentration by the SPV method was calculated from the diffusion length of minority carriers that is proportional to the carrier lifetime. From Fig. 1 (B), the carrier lifetime can be sufficiently (maximum, minimum). Value) It was found that the Z maximum value was 50% or less. Therefore, by using the method of the present invention, a large-diameter high-quality silicon single crystal wafer without Fe contamination can be obtained at a high yield by using a rectifying cylinder.

(Example 2)

A silicon wafer was manufactured from a silicon single crystal grown by a crystal pulling device equipped with a rectifying cylinder formed with a silicon carbide film. The crystal pulling apparatus was carried out by an existing crystal pulling apparatus shown in FIG. 4 except that a straightening tube used in the pulling method of the present invention was provided.

Here, in Example 2, a silicon carbide film was formed on the rectifying cylinder 4 whose main body was made of a graphite material by a sputter deposition method. For the size of the flow straightening tube 4, a flow straightening tube having an inner diameter of 250 mm was used so that the gap between the crystal and the flow straightening tube was 25 mm. The layer thickness of the silicon carbide film coated on the rectifying cylinder was set to 70 / xm, and the Fe concentration was set to 0.05 ppm or less when forming the film. Table 1 also shows the results of measuring the purity of the film formed on the rectifying tube 4 by ICP emission analysis in the same manner as in Example 1. From this, this Example 1 It can be seen that the Fe concentration of the silicon carbide film formed on the surface of the rectifying cylinder was 0.05 ppm or less.

Evaluation of Fe contamination of the manufactured silicon single crystal layer 18 was performed by the SPV method as in Example 1. The result is shown in figure 2. FIG. 2 shows that no Fe contamination around the wafer was observed as in Example 1, and that a high-quality silicon single crystal wafer with no Fe contamination was obtained up to the periphery of the wafer.

At this time, the carrier lifetime of the wafer was calculated, and the maximum value (maximum value-minimum value) was calculated to be 50% or less.

That is, it can be seen that almost the same results can be obtained regardless of whether the high-purity film used for the flow control cylinder is made of pyrolytic carbon or silicon carbide.

(Comparative example)

In the same manner as in Example 1, a silicon wafer was produced from a silicon single crystal grown by a crystal pulling apparatus equipped with a rectifying cylinder having a pyrolytic carbon film formed thereon. In this comparative example, a pyrolytic carbon film was formed under the condition that the standard for the purity of the pyrolytic carbon film formed in the rectifying cylinder 4 whose main body was made of graphite material was relaxed as compared with the example 1. The size of the flow straightening tube 4 was a 250 mm inner diameter flow straightening tube such that the gap between the crystal and the flow straightening tube was 25 mm. Table 1 also shows the results of measuring the purity of the film formed on the rectifying cylinder. From this measurement result, it can be seen that the Fe concentration of the film is 0.1 O Op pm. Otherwise, as in Example 1, a silicon single crystal was grown to produce a silicon single crystal wafer.

The Fe contamination of the manufactured silicon single crystal wafer was evaluated by the SPV method as in Example 1. The results are shown in FIG. 1 (D). From Fig. 1 (D), it can be seen that forming a film on the flow straightening tube can reduce Fe contamination, but if the purity of the film is insufficient, Fe contamination occurs.

In this comparative example as well, the carrier lifetime of Aeha was calculated (maximum value-minimum value), and the maximum value was calculated. The value at this time exceeded 50%. This was due to the fact that Fe contamination reduced the carrier lifetime near the outer periphery of the eha, and exceeded 50% due to variations in the lifetime within the eha plane. Seems to be.

Note that the present invention is not limited to the above embodiment. The above embodiment is an exemplification, and has substantially 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.

Further, in the above embodiment, the case of growing a silicon single crystal having a diameter of 8 inches has been described by way of example. However, the present invention is not limited to this, and a diameter of 8 to 16 inches or It can be applied to even larger silicon single crystals and can work more effectively. Further, it is needless to say that the present invention can also be applied to a so-called MCS method in which a horizontal magnetic field, a vertical magnetic field, a cusp magnetic field, or the like is applied to a silicon melt.

Claims

The scope of the claims

1. A silicon single crystal wafer produced from a silicon single crystal grown by the cz method, wherein the Fe concentration of the silicon single crystal wafer is 1 XI 0 ¹⁰ atoms cm ³ or less. A silicon single crystal wafer.

2. A silicon single crystal wafer produced from a silicon single crystal grown by the CZ method, wherein the carrier lifetime variation width over the entire surface of the silicon single crystal wafer is (maximum value / minimum value). A silicon single crystal wafer, wherein the fluctuation range when expressed by the Z maximum value is 50% or less.

3. A silicon single crystal wafer produced from a silicon single crystal grown by the CZ method, wherein a 10% Fe concentration around the silicon single crystal wafer is 1 X 1 ⁰ ¹ 0 atoms / cm ³ silicon single crystal Ueha, wherein less.

4. The silicon single crystal wafer according to any one of claims 1 to 3, having a diameter of 200 mm or more.

5. The silicon single crystal wafer, wherein the silicon single crystal wafer is a silicon single crystal wafer manufactured from a silicon single crystal grown using a rectifying tube in a CZ method. The silicon single crystal wafer according to claim 4.

6. In the silicon single crystal manufacturing method in which the silicon single crystal is grown while surrounding the silicon single crystal with a rectifying cylinder in the CZ method, a film with an Fe concentration of 0.05 ppm or less is formed on the surface. A method for producing a silicon single crystal, comprising growing a silicon single crystal using the rectifying cylinder thus obtained.

7. The method according to claim 6, wherein the film is made of pyrolytic carbon or silicon carbide.

8. The method for producing a silicon single crystal according to claim 6, wherein the thickness of the film is 30 μm or more.

9. A method for manufacturing a silicon single crystal wafer, comprising manufacturing a silicon single crystal wafer from a silicon single crystal manufactured by the manufacturing method according to any one of claims 6 to 8. .

10. A rectifying cylinder arranged to surround the silicon single crystal grown in the CZ method to regulate the flow of the inert gas introduced from above the chamber of the CZ device. Rectifier cylinder characterized by having a coating of 0.5 ppm or less.

11. The rectifying cylinder according to claim 10, wherein the coating is made of pyrolytic carbon or silicon carbide.

12. The rectifying cylinder according to claim 10 or 11, wherein the thickness of the coating is 30 / zm or more.

13. An apparatus for producing a silicon single crystal, comprising the rectifying cylinder according to any one of claims 10 to 12.