JP2005159013A - Inspecting method of silicon single crystal, manufacturing method of silicon wafer and manufacturing method of epitaxial wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the inspecting method of silicon single crystal, which is capable of discriminating a single crystal which permits the manufacture of an epitaxial wafer having a required wafer quality by estimating a BMD density after manufacturing the epitaxial wafer in a stage when the silicon single crystal is raised. <P>SOLUTION: The inspecting method of silicon single crystal comprises at least a manufacturing process of wafer for inspection wherein the wafer for inspection is manufactured from the silicon single crystal, a false epitaxial heat treatment process wherein heat treatment is applied on the manufactured wafer for inspection under the same heat treating condition as that applied upon manufacturing the epitaxial wafer, and a BMD density measuring process wherein the density of bulk micro defect (BMD) in the wafer is measured by applying oxygen deposition heat treatment for growing up oxygen deposit on the wafer for inspection on which the false epitaxial heat treatment process has been applied. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a silicon single crystal inspection method for discriminating a silicon single crystal capable of obtaining a desired wafer quality by predicting the BMD density after the epitaxial wafer is produced at the stage of growing the silicon single crystal, and the desired The present invention relates to a method for manufacturing an epitaxial wafer capable of manufacturing an epitaxial wafer having a BMD density of high yield and low cost.

  At present, epitaxial wafers are widely used as wafers for manufacturing individual semiconductors, bipolar ICs, and the like because of their excellent characteristics, and MOS LSIs have excellent soft errors and latch-up characteristics, so Widely used in flash memory devices and the like. Further, the demand for epitaxial wafers is increasing more and more in order to reduce the reliability failure of DRAMs due to so-called “grown-in” defects introduced during the production of silicon single crystals.

  When manufacturing a semiconductor device using such an epitaxial wafer, the presence of heavy metal impurities in the epitaxial wafer may cause the semiconductor device to have poor characteristics. Therefore, the heavy metal impurities present in the wafer are removed in the device formation region. It is necessary to remove from the vicinity of a certain wafer surface.

  In general, gettering technology is known as a technology for removing heavy metal impurities from the vicinity of the wafer surface, and one of the effective methods in this gettering technology is internal minute defects consisting of oxygen precipitates inside the wafer (bulk part). There is a method called intrinsic gettering (IG) in which (BMD: Bulk micro defect) is formed and heavy metal impurities are trapped in the strain field. Generally, in intrinsic gettering, the higher the density of BMD formed on a wafer, the higher the IG ability of the wafer. By measuring the BMD density of the wafer, the IG ability of the wafer can be evaluated. .

  Normally, BMD largely depends on the manufacturing history when a silicon single crystal is manufactured by the CZ method. For example, when manufacturing a silicon wafer (PW) subjected to mirror polishing, the BMD density of the silicon wafer Can be confirmed at the stage after single crystal growth.

  On the other hand, in the case of an epitaxial wafer, a long process is required from the production of a silicon single crystal to the formation of an epitaxial layer, and a high-temperature heat treatment is performed when forming an epitaxial layer on the silicon wafer. Oxygen precipitates present on the wafer are reduced and eliminated by the high-temperature heat treatment performed in (1). Therefore, the BMD density of the wafer changes before and after the high temperature heat treatment when forming the epitaxial layer. For example, the BMD density of the silicon single crystal measured immediately after growing the silicon single crystal and the wafer is cut out from the single crystal. The value was completely different from the BMD density of an epitaxial wafer produced by forming an epitaxial layer.

  Therefore, conventionally, in order to confirm the BMD density of an epitaxial wafer, after actually forming an epitaxial layer on a silicon wafer to produce an epitaxial wafer, the epitaxial wafer is subjected to an oxygen precipitation heat treatment or the like to measure the BMD density. In addition, as described in, for example, Examples of Patent Document 1 and Patent Document 2, various wafer qualities are measured by performing thermal simulation after manufacturing an epitaxial wafer.

  However, when the BMD density is measured after actually manufacturing the epitaxial wafer in this way, for example, if the quality of the epitaxial wafer does not satisfy the user's request and it is determined as a defective product, the epitaxial wafer is manufactured. The time and cost spent up to that time has been a great loss, which has been one of the factors that hinders productivity improvement and cost reduction in the production of epitaxial wafers.

Japanese Patent Laid-Open No. 10-50715 Japanese Patent Laid-Open No. 10-223641

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to predict the BMD density after producing an epitaxial wafer at the stage of growing a silicon single crystal and to obtain a desired wafer quality. It is an object of the present invention to provide a method for inspecting a silicon single crystal capable of discriminating a single crystal capable of producing an epitaxial wafer having a thickness of the epitaxial wafer, and an epitaxial wafer capable of producing an epitaxial wafer having a desired BMD density at a high yield and at a low cost. It is to provide a manufacturing method.

  In order to achieve the above object, according to the present invention, there is provided a method for inspecting a silicon single crystal, comprising at least an inspection wafer production step for producing an inspection wafer from the silicon single crystal, and the produced inspection wafer. A pseudo-epitaxial heat treatment step for performing heat treatment under the same heat treatment conditions as those used when fabricating an epitaxial wafer on the substrate, and oxygen precipitation for growing oxygen precipitates on the inspection wafer subjected to the pseudo-epitaxial heat treatment step There is provided a method for inspecting a silicon single crystal comprising a BMD density measuring step of performing a heat treatment to measure the density of internal minute defects (BMD) of a wafer (claim 1).

  As described above, the silicon single crystal was grown by performing at least the inspection wafer manufacturing process, the pseudo-epitaxial heat treatment process, and the BMD density measurement process, without actually manufacturing the epitaxial wafer. Since the single crystal that can obtain the desired wafer quality can be determined by predicting the BMD density after the epitaxial wafer is manufactured at the stage, for example, in the manufacture of the conventional epitaxial wafer, the BMD guaranteed value or the standard value is not satisfied. It is possible to greatly reduce the time loss and manufacturing cost loss that occurred when manufacturing a non-defective product, and after that, using only a silicon single crystal with a desired BMD density guaranteed, an epitaxial wafer can be formed. Manufacturing yields in the production of epitaxial wafers. Since can be improved, it is possible to improve and reduce costs of production of the epitaxial wafer.

  In this case, in the pseudo-epitaxial heat treatment step, it is preferable that the inspection wafer is heat-treated at a heat treatment temperature of 1100 ° C. or higher and 1250 ° C. or lower for 5 to 40 minutes.

  In this way, by performing heat treatment for 5 to 40 minutes at a heat treatment temperature of 1100 ° C. or more and 1250 ° C. or less on the inspection wafer in the pseudo epitaxial heat treatment step, heat similar to the heat treatment performed when actually forming the epitaxial layer is performed. Since the inspection wafer can be heat-treated with a history, the BMD density of the inspection wafer is then measured in the BMD density measurement process, so that the density of the BMD formed when the epitaxial wafer is actually fabricated is very high. Can be predicted with accuracy.

  Further, in the oxygen precipitation heat treatment in the BMD density measurement step, it is preferable to heat-treat the inspection wafer at 1000 ° C. for 16 hours (Claim 3), and in the oxygen precipitation heat treatment in the BMD density measurement step, It is preferable to perform the heat treatment at 800 ° C. for 4 hours before the heat treatment at 1000 ° C. for 16 hours on the inspection wafer.

  Thus, in the oxygen precipitation heat treatment in the BMD density measurement step, the inspection wafer is subjected to heat treatment at 1000 ° C. for 16 hours, more preferably at 800 ° C. for 4 hours + 1000 ° C. for 16 hours. Since the existing oxygen precipitates can be easily grown to a detectable size, the BMD density of the inspection wafer can be measured with high accuracy.

In addition, the present invention can provide a method for producing a silicon wafer, characterized in that a silicon wafer is produced from a silicon single crystal in which a desired BMD density is guaranteed by the silicon single crystal inspection method of the present invention. (Claim 5).
Thus, by manufacturing a silicon wafer from a silicon single crystal in which a desired BMD density is guaranteed by the silicon single crystal inspection method of the present invention, a silicon wafer capable of producing an epitaxial wafer having a desired BMD density at a high yield is obtained. Can be easily obtained.

Furthermore, the present invention can provide an epitaxial wafer manufacturing method characterized by manufacturing an epitaxial wafer by forming an epitaxial layer on the silicon wafer manufactured by the above-described silicon wafer manufacturing method of the present invention ( Claim 6).
As described above, an epitaxial wafer having a desired BMD density can be manufactured at a high yield by forming an epitaxial layer on the silicon wafer manufactured by the silicon wafer manufacturing method of the present invention and manufacturing the epitaxial wafer. Thus, the productivity of the epitaxial wafer can be improved and the cost can be reduced.

  According to the present invention, in the method of manufacturing an epitaxial wafer by forming an epitaxial layer on the silicon wafer after manufacturing the silicon wafer from the silicon single crystal, the silicon wafer is inspected when the silicon wafer is manufactured from the silicon single crystal. A pseudo-epitaxial heat treatment step for producing a wafer for the test and performing a heat treatment under the same heat treatment conditions as the heat treatment applied at the time of forming the epitaxial layer on the inspection wafer, and oxygen precipitation for growing oxygen precipitates A BMD density measuring step is performed to measure the density of internal micro defects (BMD) of the wafer by performing a heat treatment, and the BMD density of the inspection wafer is measured, and a desired BMD density is guaranteed based on the measurement result of the BMD density. A silicon single crystal produced or a silicon wafer produced from the silicon single crystal Method for manufacturing an epitaxial wafer, characterized in that to manufacture the epitaxial wafer is provided have (claim 7).

  By manufacturing an epitaxial wafer in this manner, an epitaxial wafer having a desired BMD density can be manufactured at a high yield, and defects have occurred since a conventional epitaxial wafer is manufactured. Since the time loss and the manufacturing cost loss can be greatly reduced, the productivity and cost reduction of the epitaxial wafer can be achieved.

In this case, it is preferable that the inspection wafer is manufactured before the slicing step of cutting the silicon wafer from the silicon single crystal is performed.
Thus, before the slicing step of cutting the silicon wafer from the silicon single crystal is performed, an inspection wafer is manufactured from the silicon single crystal, and the pseudo-epitaxial heat treatment step and the BMD density measurement step are performed to perform the inspection wafer. If the BMD density is measured, the quality of the wafer quality can be determined by predicting the BMD density when the epitaxial wafer is produced after the silicon single crystal is grown. Loss and manufacturing cost loss can be further reduced.

  As described above, according to the present invention, at the stage of growing a silicon single crystal, the BMD density when the epitaxial wafer is produced is predicted, and a single crystal that can produce an epitaxial wafer having a desired wafer quality is discriminated. Can do. Therefore, it is possible to manufacture an epitaxial wafer using a silicon single crystal in which a desired BMD density is guaranteed, and thereby a high quality epitaxial wafer having a desired BMD density can be manufactured with a high yield. In addition, even if the wafer quality is poor, it can be identified at the silicon single crystal stage, greatly reducing the time loss and manufacturing cost loss required to manufacture the conventional epitaxial wafer. Thus, the productivity of the epitaxial wafer can be improved and the cost can be reduced.

Hereinafter, although an embodiment is described about the present invention, the present invention is not limited to these.
In order to improve productivity and reduce costs in manufacturing an epitaxial wafer, the present inventors have made a wafer after manufacturing an epitaxial wafer at an early stage of the epitaxial wafer manufacturing process, particularly at the stage of growing a silicon single crystal. We thought that it would be good if the BMD density of the material could be predicted. As a result, an inspection wafer is manufactured from the silicon single crystal, and the pseudo wafer is formed at the stage of growing the silicon single crystal by performing a pseudo-epitaxial heat treatment process and a BMD density measurement process on the manufactured inspection wafer. It is possible to determine the single crystal that can obtain the desired wafer quality by predicting the density, thereby improving the yield of the epitaxial wafer and preventing the production of defective products. The present invention has been completed by finding that the loss of manufacturing cost can be reduced.

Hereinafter, the silicon single crystal inspection method of the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto. FIG. 1 is a flowchart showing an example of a silicon single crystal inspection method according to the present invention.
First, an inspection wafer is manufactured from a silicon single crystal to be inspected in the inspection wafer manufacturing process (process A in FIG. 1). In this inspection wafer production process, the method for producing the inspection wafer from the silicon single crystal is not particularly limited. For example, the wafer was cut from the silicon single crystal using an inner peripheral cutting machine or a wire saw. Thereafter, a wafer for inspection can be easily produced by subjecting the obtained wafer to a wafer processing step such as chamfering, lapping, etching, polishing, or the like that is conventionally performed.

  Next, a pseudo epitaxial heat treatment step is performed on the manufactured inspection wafer (step B in FIG. 1). In this pseudo-epitaxial heat treatment process, heat treatment is performed under the same heat treatment conditions (thermal history) as the heat treatment performed when the epitaxial wafer is manufactured on the inspection wafer, thereby forming oxygen precipitates formed on the inspection wafer. With respect to (nucleus), it is possible to cause the same behavior as the reduction / extinction of oxygen precipitates generated when an epitaxial layer is actually formed on a silicon wafer.

  At this time, in the pseudo-epitaxial heat treatment step, it is preferable to perform heat treatment on the inspection wafer at a heat treatment temperature of 1100 ° C. or higher and 1250 ° C. or lower for 5 to 40 minutes. Generally, when an epitaxial layer is formed on a silicon wafer, a heat treatment is performed at a heat treatment temperature of 1100 ° C. or higher and 1250 ° C. or lower for 5 to 40 minutes. Therefore, when the pseudo-epitaxial heat treatment step is performed on the inspection wafer, the pseudo-epitaxial heat treatment step may be performed at the same heat treatment temperature as when the epitaxial layer is formed, that is, at a heat treatment temperature of 1100 ° C. or higher and 1250 ° C. or lower. preferable.

  Similarly, the heat treatment time of the pseudo epitaxial heat treatment step is preferably set to 5 to 40 minutes in accordance with the heat treatment conditions for actually forming the epitaxial layer. In particular, by performing the pseudo-epitaxial heat treatment process for about 20 minutes, the behavior of oxygen precipitates similar to the decrease / extinction of oxygen precipitates generated when forming an epitaxial layer is stably generated in the inspection wafer, and the epitaxial wafer is epitaxially grown. It becomes possible to predict the BMD density when the wafer is manufactured almost accurately. Therefore, the heat treatment time of the pseudo epitaxial heat treatment process is more preferably 20 minutes, whereby the single crystal can be inspected efficiently and with high accuracy.

Then, after performing the pseudo-epitaxial heat treatment process as described above, a BMD density measurement process for measuring the BMD density of the inspection wafer is performed (process C in FIG. 1).
In this BMD density measurement step, first, an oxygen precipitation heat treatment is performed on the inspection wafer to grow oxygen precipitates to a detectable size. At this time, in the oxygen precipitation heat treatment, for example, the inspection wafer may be heat-treated at 1000 ° C. for 16 hours, more preferably 800 ° C. for 4 hours + 1000 ° C. for 16 hours. By performing the above, oxygen precipitates present on the inspection wafer can be easily grown to a detectable size.

  Further, the inspection wafer that has been subjected to the oxygen precipitation heat treatment is then subjected to, for example, selective etching to reveal oxygen precipitates, and measure the BMD density of the inspection wafer by counting defects using a microscope or the like. be able to.

  Thus, the BMD density of the inspection wafer measured after performing the pseudo-epitaxial heat treatment step has a good correlation with the BMD density formed on the wafer when an epitaxial wafer is actually produced from a silicon single crystal. Yes. Therefore, the BMD density after the epitaxial wafer fabrication can be predicted based on the BMD density measured by this inspection wafer, and it is highly accurate whether or not an epitaxial wafer having a desired quality can be manufactured from the single crystal to be inspected. Can be determined.

  As described above, according to the method for inspecting a silicon single crystal of the present invention, an epitaxial wafer having a desired quality can be manufactured by predicting the BMD density when the epitaxial wafer is produced at the stage of growing the silicon single crystal. Single crystals can be identified. Therefore, it is possible to manufacture an epitaxial wafer using only a single crystal with a desired BMD density guaranteed, and the yield of the epitaxial wafer can be improved. On the other hand, since the single crystal judged to be defective by the inspection result does not need to be subjected to subsequent wafer processing steps or epitaxial layer formation steps, when a defective product is manufactured in the conventional epitaxial wafer manufacturing as described above. Time loss and manufacturing cost loss that have occurred can be significantly reduced.

  Further, by manufacturing a silicon wafer from a silicon single crystal with a desired BMD density guaranteed by the inspection method of the present invention, it is possible to easily obtain a silicon wafer capable of manufacturing an epitaxial wafer having a desired BMD density with a high yield. Can do. Further, by manufacturing an epitaxial wafer using such a silicon wafer, the productivity of the epitaxial wafer can be improved and the cost can be reduced.

Next, the manufacturing method of the epitaxial wafer of this invention is demonstrated.
First, after manufacturing a silicon single crystal by the Czochralski method (CZ method), the floating zone method (FZ method) or the like, an inspection wafer is manufactured when a silicon wafer is manufactured from the obtained silicon single crystal.

  This inspection wafer is manufactured (cut out or extracted) at any stage of the slicing process, chamfering process, lapping process, etching process, polishing process, etc. performed when manufacturing a silicon wafer from a silicon single crystal. For example, if the inspection wafer is manufactured before the slicing process of cutting the silicon wafer from the silicon single crystal is performed, the wafer is actually formed at the stage of the silicon single crystal. As the wafer quality can be judged by predicting the BMD density of the wafer, it is not necessary to perform not only the epitaxial growth process but also the wafer processing process such as chamfering process and lapping process when the silicon single crystal is defective. , Time loss and manufacturing cost loss can be greatly reducedIn particular, when the diameter is 200 mm or more, the crystal weight increases, so the raw material cost also increases. In the case of no, it is preferable that the quality can be determined at an early stage so that it can be reused.

  Next, the pseudo-epitaxial heat treatment step and the BMD density measurement step described above are performed on the manufactured inspection wafer, and the BMD density of the inspection wafer is measured. Then, based on the measurement result of the obtained BMD density, a silicon single crystal in which the desired BMD density is guaranteed (if the inspection wafer is manufactured after the slicing process is performed, the desired BMD density is guaranteed. An epitaxial wafer is manufactured using only a silicon wafer manufactured from a silicon single crystal.

In the present invention, a specific method for producing an epitaxial wafer from a silicon single crystal with a desired BMD density guaranteed is not particularly limited, and an epitaxial wafer is produced using a conventional method. Can do. For example, a silicon single crystal with a desired BMD density guaranteed is sliced and processed into a wafer shape, and a mirror silicon wafer is produced by chamfering, lapping, etching, mirror polishing, etc., and then in an H ₂ atmosphere. An epitaxial wafer having an epitaxial layer formed on the wafer surface is manufactured by performing an epitaxial heat treatment at a temperature of 1100 ° C. to 1250 ° C. for 5 to 40 minutes while supplying a silicon compound gas such as SiCl ₄ or SiHCl _3. be able to.

  By manufacturing an epitaxial wafer as described above, an epitaxial wafer having a desired BMD density can be manufactured at a high yield, and further, a conventional epitaxial wafer having a defect cannot be manufactured. Loss and manufacturing cost loss can be significantly reduced, and the epitaxial wafer can be manufactured at low cost by improving the productivity and reducing the cost of the epitaxial wafer. Furthermore, since the epitaxial wafer manufactured by the manufacturing method of the present invention has a desired BMD density, for example, it is possible to omit the inspection of the BMD density performed after the conventional epitaxial wafer is manufactured.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to these.
(Examples 1 to 3, Comparative Example 1)
First, a silicon single crystal doped with nitrogen having a diameter of 300 mm and a resistivity of 10 Ω · cm was grown by the CZ method. Next, after slicing the wafer from each crystal portion of the silicon single crystal using a slicer, chamfering, lapping, etching, and mirror polishing were performed to produce a plurality of inspection wafers.

  And the pseudo-epitaxial heat treatment process was performed on each of the heat treatment conditions at 1200 ° C. for 40, 20, and 5 minutes on the inspection wafer thus produced. After that, each inspection wafer was subjected to oxygen precipitation heat treatment at 800 ° C. for 4 hours + 1000 ° C. for 16 hours, and then the wafer was cleaved, and the cleaved surface was selectively etched to reveal oxygen precipitates. The BMD density of the inspection wafer was measured using a microscope (Examples 1 to 3).

  For comparison, after slicing the wafer from each crystal portion of the nitrogen-doped silicon single crystal grown above using a slicer, chamfering, lapping, etching, and mirror polishing were performed to produce a plurality of silicon wafers. . Half of the fabricated silicon wafers were subjected to oxygen precipitation heat treatment at 800 ° C. for 4 hours + 1000 ° C. for 16 hours, and then the wafer was cleaved, and selective cleavage was performed on the cleavage surface to reveal oxygen precipitates. Then, the BMD density was measured using an optical microscope (Comparative Example 1).

Further, the remaining half of the silicon wafer produced above was subjected to epitaxial heat treatment at 1200 ° C. for 20 minutes while supplying SiHCl ₃ gas in an H ₂ atmosphere, and an epitaxial layer having an epitaxial layer grown on the wafer surface was obtained. A wafer was manufactured. These epitaxial wafers were subjected to oxygen precipitation heat treatment in the same manner as described above, and after selective etching, the BMD density of the reference epitaxial wafer was measured.

  Here, FIG. 2 (a) shows the BMD density (Example 1), the BMD density of the silicon wafer (Comparative Example 1), and the reference when the inspection wafer is subjected to a pseudo-epitaxial heat treatment process at 1200 ° C. for 40 minutes. FIG. 2B shows the result of measuring the BMD density of the epitaxial wafer to be obtained, and FIG. 2B shows the result of obtaining the correlation between the BMD density of Example 1 and Comparative Example 1 and the BMD density of the reference epitaxial wafer. Show.

  FIG. 3 shows a case where the result of measuring the BMD density of Example 2 in which a pseudo-epitaxial heat treatment process at 1200 ° C. for 20 minutes was performed on an inspection wafer instead of Example 1 of FIG. FIG. 4 shows a case in which the result of measuring the BMD density of Example 3 in which a pseudo-epitaxial heat treatment process at 1200 ° C. for 5 minutes is performed on an inspection wafer is shown.

Further, for the inspection wafers of Examples 1 to 3, the silicon wafer of Comparative Example 1, and the reference epitaxial wafer, the wafer having a BMD density of 1 × 10 ⁵ / cm ² or more is determined to be acceptable. The quality was determined, and the consistency between the results obtained in Examples 1 to 3 and Comparative Example 1 and the results obtained with the epitaxial wafer was determined. The results are shown in Table 1 below.

  As shown in FIGS. 2 to 4, it can be seen that the BMD density measured in Examples 1 to 3 in which the pseudo-epitaxial heat treatment process was performed has a good correlation with the BMD density of the epitaxial wafer. It can be seen that the BMD density measured in 1 shows almost no correlation with the BMD density of the epitaxial wafer. Furthermore, as shown in Table 1, it can be seen that Examples 1 to 3 have a better match rate with the BMD density of the epitaxial wafer than Comparative Example 1. That is, by measuring the BMD density of Examples 1 to 3 in which the pseudo-epitaxial heat treatment process is performed in this way, the BMD density of the epitaxial wafer can be predicted with high accuracy, and the single crystal has the desired quality. It is possible to determine with high accuracy whether or not the wafer can be manufactured.

  Furthermore, when comparing the BMD density measured in Examples 1 to 3, the longer the pseudo-epitaxial heat treatment step, the better the consistency with the BMD density measured on the epitaxial wafer. It can be seen that if the epitaxial heat treatment step is performed for 20 minutes, a coincidence rate close to 100% can be obtained. Therefore, it is preferable to perform the pseudo-epitaxial heat treatment step for 20 minutes, which makes it possible to inspect the silicon single crystal more efficiently and with high accuracy.

(Example 4, Comparative Example 2)
First, a silicon single crystal having a diameter of 300 mm and a resistivity of 10 Ω · cm was grown by CZ method without nitrogen doping. Next, after slicing the wafer from each crystal portion of the silicon single crystal using a slicer, chamfering, lapping, etching, and mirror polishing were performed to produce a plurality of inspection wafers.

  Then, a pseudo-epitaxial heat treatment step was performed on the inspection wafer thus produced at 1200 ° C. under a heat treatment condition of 20 minutes. Thereafter, each inspection wafer is subjected to oxygen precipitation heat treatment at 800 ° C. for 4 hours + 1000 ° C. for 16 hours, and then the wafer is cleaved. After the selective etching is performed on the cleaved surface, an inspection wafer is formed using an optical microscope. BMD density was measured (Example 4).

  For comparison, after slicing a wafer using a slicer from each crystal portion of the silicon single crystal not subjected to nitrogen doping, a plurality of silicon wafers were produced by chamfering, lapping, etching, and mirror polishing. . Then, half of the produced silicon wafers were subjected to oxygen precipitation heat treatment at 800 ° C. for 4 hours + 1000 ° C. for 16 hours, and then the wafer was cleaved, and after selective etching of the cleaved surface, an optical microscope was used. The BMD density was measured (Comparative Example 2).

Further, the remaining half of the silicon wafer was subjected to an epitaxial heat treatment at 1200 ° C. for 20 minutes while supplying SiHCl ₃ gas in an H ₂ atmosphere to produce an epitaxial wafer having an epitaxial layer grown on the wafer surface. Similarly, the BMD density of the epitaxial wafer was measured.

  FIG. 5 (a) shows the results of measuring the BMD density of the inspection wafer of Example 4, the BMD density of the silicon wafer of Comparative Example 2, and the BMD density of the reference epitaxial wafer, and FIG. 5 (b). The result of having calculated | required the correlation with the BMD density of Example 4 and Comparative Example 2 and the BMD density of the epitaxial wafer used as a reference | standard is shown.

  As shown in FIG. 5, the BMD density of the epitaxial wafer produced from the single crystal not doped with nitrogen is very low below the lower limit of detection, but the BMD density measured with the inspection wafer of Example 4 Shows that it is accurately reproduced, and the BMD density of the epitaxial wafer is predicted with high accuracy. On the other hand, BMD was observed in the silicon wafer of Comparative Example 2 and showed a value completely different from that of the epitaxial wafer.

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

It is a flowchart which shows an example of the test | inspection method of the silicon single crystal of this invention. (A) is a graph which shows the result of having measured the BMD density of the inspection wafer of Example 1, the silicon wafer of Comparative Example 1, and the reference epitaxial wafer, and (b) is Example 1 and Comparative Example. It is a graph which shows the result of having calculated | required the correlation of BMD density of 1 and the BMD density of an epitaxial wafer. (A) is a graph which shows the result of having measured the BMD density of the inspection wafer of Example 2, the silicon wafer of Comparative Example 1, and the epitaxial wafer used as a reference, and (b) is Example 2 and Comparative Example. It is a graph which shows the result of having calculated | required the correlation of BMD density of 1 and the BMD density of an epitaxial wafer. (A) is a graph which shows the result of having measured the BMD density of the inspection wafer of Example 3, the silicon wafer of Comparative Example 1, and the epitaxial wafer used as a reference, and (b) is Example 3 and Comparative Example. It is a graph which shows the result of having calculated | required the correlation of BMD density of 1 and the BMD density of an epitaxial wafer. (A) is a graph which shows the result of having measured the BMD density of the inspection wafer of Example 4, the silicon wafer of the comparative example 2, and the epitaxial wafer used as a reference, (b) is Example 4 and a comparative example. 2 is a graph showing a result of obtaining a correlation between a BMD density of 2 and a BMD density of an epitaxial wafer.

Claims (8)

  A method for inspecting a silicon single crystal, which is at least the same as the inspection wafer production process for producing an inspection wafer from the silicon single crystal, and the heat treatment applied when producing the epitaxial wafer on the produced inspection wafer And a density of internal micro-defects (BMD) of the wafer by performing an oxygen precipitation heat treatment step for growing oxygen precipitates on the inspection wafer subjected to the pseudo-epitaxial heat treatment step. A method for inspecting a silicon single crystal, comprising: a BMD density measuring step for measuring the above.   2. The method for inspecting a silicon single crystal according to claim 1, wherein, in the pseudo-epitaxial heat treatment step, the inspection wafer is subjected to heat treatment at a heat treatment temperature of 1100 [deg.] C. to 1250 [deg.] C. for 5 to 40 minutes.   3. The method for inspecting a silicon single crystal according to claim 1, wherein in the oxygen precipitation heat treatment in the BMD density measurement step, the heat treatment is performed on the inspection wafer at 1000 ° C. for 16 hours.   4. The silicon single crystal according to claim 3, wherein, in the oxygen precipitation heat treatment in the BMD density measurement step, the heat treatment is performed at 800 ° C. for 4 hours before the heat treatment at 1000 ° C. for 16 hours. Crystal inspection method.   5. A method for producing a silicon wafer, comprising producing a silicon wafer from a silicon single crystal having a desired BMD density guaranteed by the method for inspecting a silicon single crystal according to any one of claims 1 to 4.   An epitaxial wafer manufacturing method, comprising: forming an epitaxial layer on a silicon wafer manufactured by the silicon wafer manufacturing method according to claim 5; and manufacturing the epitaxial wafer.   In the method of manufacturing an epitaxial wafer by forming a silicon wafer from a silicon single crystal and then forming an epitaxial layer on the silicon wafer, an inspection wafer is manufactured when the silicon wafer is manufactured from the silicon single crystal, and the inspection is performed. The wafer is subjected to a pseudo-epitaxial heat treatment process in which heat treatment is performed at least under the same heat treatment conditions as in the formation of the epitaxial layer, and an oxygen precipitation heat treatment for growing oxygen precipitates. A BMD density measurement step for measuring the density of defects (BMD) is performed to measure the BMD density of the inspection wafer, and the silicon single crystal or the silicon in which the desired BMD density is guaranteed based on the measurement result of the BMD density Using silicon wafers made from single crystals, epitaxial wafers Method for manufacturing an epitaxial wafer, characterized in that to manufacture the Doha.   8. The method of manufacturing an epitaxial wafer according to claim 7, wherein the inspection wafer is manufactured before a slicing step of cutting a silicon wafer from a silicon single crystal is performed.

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