Evaluation method for pore concentration of silicon single-crystal wafer

Abstract

To provide a method of enabling pore concentration evaluation by determining a silicon single-crystal wafer in which a spectrum is not obtained by a DLTS method after Pt diffusion and eliminating the cause.SOLUTION: An evaluation method for pore concentration of a silicon single-crystal wafer includes in this order: step 1 of performing donor killer heat treatment when the oxygen concentration of a silicon single-crystal wafer is more than or equal to a predetermined value; step 2 of measuring a resistivity R1 of the wafer; step 3 of applying and diffusing Pt on a surface of the wafer; step 4 of measuring a resistivity R2 of the Pt diffused wafer; step 5 of obtaining a ratio between R1 and R2; step 6 of removing a predetermined region on the surface of the wafer when the ratio is more than the predetermined value; step 7 of obtaining the Pt concentration by a DLTS method for the wafer in which the ratio in the step 5 is less than or equal to the predetermined value or the ratio becomes less than or equal to the predetermine value by the step 6; and step 8 of estimating the pore concentration of the wafer on the basis of the Pt concentration obtained by the DLTS method.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for evaluating the vacancy concentration of a silicon single crystal wafer. [Background technology]

[0002] Grown-in defects (defects introduced during growth) are formed in silicon single crystal wafers during single crystal growth. Grown-in defects include interstitial silicon agglomerates, interstitial silicon, vacancies, and vacancy agglomerates. Single crystal defect regions are distinguished based on the form of the grown-in defects, and include regions where interstitial silicon agglomerates exist (hereinafter referred to as I-rich regions), regions where point defect agglomerates do not exist and interstitial silicon predominates over vacancies (hereinafter referred to as Ni regions), regions where point defect agglomerates do not exist and vacancies predominate over interstitial silicon (hereinafter referred to as Nv regions), and regions where vacancy agglomerates exist (hereinafter referred to as V-rich regions). In particular, the Ni and Nv regions are called NPC (Nearly Perfect Crystal) regions because they do not contain point defect agglomerates.

[0003] Point defects (interstitial silicon, vacancies) are important indicators of the characteristics of such silicon single crystal wafers. Point defects affect device characteristics by agglomerating or forming complexes during processing, so a method for evaluating their behavior is required. Various methods for evaluating point defects have been reported, and a highly sensitive vacancy concentration evaluation method utilizes the fact that the concentration of substitutional Pt formed by intentional Pt contamination is proportional to the vacancy concentration before intentional contamination. This method determines the substitutional Pt concentration from deep level transient spectroscopy (DLTS) measurements after Pt diffusion, and evaluates the vacancy concentration (Patent Document 1). However, when evaluating vacancy concentration using the above method, it has been found that in some silicon single crystal wafers, a spectrum cannot be obtained using the DLTS method after Pt diffusion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-334886 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for determining silicon single crystal wafers from which a spectrum cannot be obtained by the DLTS method after Pt diffusion, and for eliminating the cause of the problem, thereby enabling vacancy concentration evaluation. [Means for solving the problem]

[0006] The present invention has been made to achieve the above object, A method for evaluating a vacancy concentration in a silicon single crystal wafer, comprising: a step 1 of measuring the oxygen concentration of a silicon single crystal wafer to be measured, and performing donor killer heat treatment if the measured oxygen concentration is equal to or higher than a predetermined value; a step 2 of measuring the resistivity R1 of the silicon single crystal wafer; Step 3 of applying Pt to the surface of the silicon single crystal wafer and then performing heat treatment to diffuse the Pt; a step 4 of measuring the resistivity R2 of the Pt-diffused silicon single crystal wafer; Step 5: determining the ratio of the resistivity R1 to the resistivity R2; a step 6 of removing a predetermined region of the surface of the silicon single crystal wafer into which Pt has been diffused when the ratio of the resistivity R1 to the resistivity R2 obtained above is greater than a predetermined value; a step 7 of determining a Pt concentration by a DLTS method for the Pt-diffused silicon single crystal wafer in which the ratio of resistivity R1 to resistivity R2 determined in the step 5 is equal to or less than a predetermined value, or in which the ratio of resistivity R1 to resistivity R2 has become equal to or less than a predetermined value by removing a predetermined region of the surface in the step 6; a step 8 of estimating the vacancy concentration of the silicon single crystal wafer from the Pt concentration obtained by the DLTS method; The present invention provides a method for evaluating the vacancy concentration of a silicon single crystal wafer, comprising the steps of:

[0007] This method for evaluating the vacancy concentration of silicon single crystal wafers can first distinguish silicon single crystal wafers in which the carrier concentration in the substrate surface layer has changed due to Pt diffusion, making it impossible to detect a spectrum using the DLTS method.Furthermore, by removing the carrier concentration change portion of the silicon single crystal wafer in which the spectrum cannot be detected using the DLTS method, the spectrum can be made detectable using the DLTS method, making it possible to evaluate the vacancy concentration.

[0008] In this case, it is preferable that the predetermined value of the oxygen concentration in step 1 is set to 5 ppma.

[0009] Thus, when the oxygen concentration is 5 ppma or more, there is a possibility that thermal donors are present in the silicon single crystal wafer, and therefore it is preferable to remove the thermal donors in advance.

[0010] Furthermore, it is preferable that the ratio of the resistivity R1 to the resistivity R2 obtained in step 5 is |(R2 / R1)-1|.

[0011] In this case, in step 6, if the value of |(R2 / R1)-1| is greater than 0.15, it is preferable to remove a predetermined region on the surface of the silicon single crystal wafer into which Pt has been diffused.

[0012] In this way, whether R1 and R2 are comparable or not is preferably determined based on whether |(R2 / R1)-1| is greater than 0.15, in particular. [Effects of the Invention]

[0013] The method for evaluating the vacancy concentration of a silicon single crystal wafer of the present invention can first identify silicon single crystal wafers in which the carrier concentration in the substrate surface layer has changed due to Pt diffusion and the spectrum cannot be detected by the DLTS method.Furthermore, by removing the carrier concentration change portion of the silicon single crystal wafer in which the spectrum cannot be detected by the DLTS method, the spectrum can be detected by the DLTS method, making it possible to evaluate the vacancy concentration. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a flow chart showing an outline of an example of a method for evaluating the vacancy concentration of a silicon single crystal wafer according to the present invention. [Figure 2] 1 is a graph showing the measurement results of the resistivity distribution in the depth direction by spreading resistance analysis in Example 1. [Figure 3] 1 is a graph showing spectra obtained by DLTS measurement in Example 1 and Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be described in detail below, but the present invention is not limited thereto.

[0016] The present invention provides a method for evaluating a vacancy concentration in a silicon single crystal wafer, comprising: a step 1 of measuring the oxygen concentration of a silicon single crystal wafer to be measured, and performing donor killer heat treatment if the measured oxygen concentration is equal to or higher than a predetermined value; a step 2 of measuring the resistivity R1 of the silicon single crystal wafer; Step 3 of applying Pt to the surface of the silicon single crystal wafer and then performing heat treatment to diffuse the Pt; a step 4 of measuring the resistivity R2 of the Pt-diffused silicon single crystal wafer; Step 5: determining the ratio of the resistivity R1 to the resistivity R2; a step 6 of removing a predetermined region of the surface of the silicon single crystal wafer into which Pt has been diffused when the ratio of the resistivity R1 to the resistivity R2 obtained above is greater than a predetermined value; a step 7 of determining a Pt concentration by a DLTS method for the Pt-diffused silicon single crystal wafer in which the ratio of resistivity R1 to resistivity R2 determined in the step 5 is equal to or less than a predetermined value, or in which the ratio of resistivity R1 to resistivity R2 has become equal to or less than a predetermined value by removing a predetermined region of the surface in the step 6; a step 8 of estimating the vacancy concentration of the silicon single crystal wafer from the Pt concentration obtained by the DLTS method; The method for evaluating the vacancy concentration of a silicon single crystal wafer is characterized by comprising the steps of:

[0017] Each step will be described in more detail below with reference to steps 1 to 8 in the flow chart of FIG.

[0018] Step 1 of the method of the present invention is a step of measuring the oxygen concentration of a silicon single crystal wafer to be measured, and performing donor killer heat treatment if the measured oxygen concentration is equal to or greater than a predetermined value.

[0019] The silicon single crystal wafer to be measured is not particularly limited, and can be, for example, a wafer sliced ​​from a silicon single crystal ingot manufactured by the CZ method or the FZ method. In step 1, first, the oxygen concentration of the silicon single crystal wafer to be measured is measured using FT-IR (Fourier transform infrared spectroscopy) or the like. If the oxygen concentration measured here is equal to or higher than a predetermined value, donor killer heat treatment is performed. The predetermined oxygen concentration value used as the criterion for donor killer heat treatment in step 1 can be, for example, an oxygen concentration of 5 ppma or higher. Note that the JEITA standard can be used for the oxygen concentration of silicon single crystal wafers.

[0020] When the oxygen concentration of a silicon single crystal wafer is above a certain value, particularly above 5 ppma, there is a possibility that thermal donors are present in the silicon single crystal wafer, and the subsequent Pt diffusion heat treatment also acts as a heat treatment in which a donor killer is performed. As a result, the change in resistivity before and after the diffusion heat treatment includes the change in resistivity caused by the donor killer during the Pt diffusion heat treatment, so it is necessary to perform a donor killer heat treatment before the Pt diffusion heat treatment to remove the thermal donors in advance.

[0021] Here, the donor killer heat treatment may be any donor killer heat treatment that is normally performed on silicon single crystal wafers, such as donor killer heat treatment performed in a nitrogen atmosphere at 650° C. for 20 minutes.

[0022] Step 2 of the method of the present invention is a step of measuring the resistivity R1 of the silicon single crystal wafer. If the reference value for whether or not to perform donor killer heat treatment in step 1 is 5 ppma, when measuring the oxygen concentration of the silicon single crystal wafer to be measured in step 1, if the oxygen concentration is 5 ppma or more, donor killer heat treatment is performed, and then the measurement of resistivity R1 in step 2 is carried out. On the other hand, under these conditions, if the oxygen concentration measured in step 1 is less than 5 ppma, the measurement of resistivity R1 is carried out without performing donor killer heat treatment.

[0023] Furthermore, it is desirable to measure the resistivity of silicon single crystal wafers using the non-destructive and simple four-probe method.

[0024] Step 3 of the method of the present invention is a step of applying Pt to the surface of the silicon single crystal wafer and then performing a heat treatment to diffuse the Pt. In this step 3, after measuring the resistivity R1 in step 2, Pt (platinum) is diffused into the silicon single crystal wafer.

[0025] More specifically, the diffusion of Pt in this process can be carried out as follows, but is not limited to this. First, the native oxide film on the surface of the silicon single crystal wafer is removed using hydrofluoric acid or the like, and then the wafer is immersed in SC1 liquid to form a chemical oxide film on the wafer surface, making it hydrophilic. Next, a Pt solution with a Pt concentration of 100 ppm or more and 1000 ppm or less, prepared by diluting atomic absorption standard solution with pure water, is applied to the surface of the silicon single crystal wafer by spin coating. The silicon single crystal wafer is then subjected to a heat treatment at a temperature range of 600 to 800°C.

[0026] Step 4 of the method of the present invention is a step of measuring the resistivity R2 of the silicon single crystal wafer into which Pt has been diffused in step 3. In this step 4, the resistivity R2 of the silicon single crystal wafer after the Pt diffusion heat treatment can be measured by the same method as used to measure the resistivity R1.

[0027] Step 5 of the method of the present invention is a step of determining the ratio of the resistivity R1 measured in step 2 to the resistivity R2 measured in step 4. The ratio of the resistivity R1 to the resistivity R2 determined in step 5 can be |(R2 / R1)-1| (i.e., the absolute value of the value obtained by dividing the value of R2 by the value of R1 and subtracting 1).

[0028] Step 6 of the method of the present invention is a step of removing a predetermined region on the surface of the silicon single crystal wafer into which Pt has been diffused if the ratio of resistivity R1 to resistivity R2 determined in step 5 is greater than a predetermined value. In step 6, the predetermined value can be determined as follows: if the value of |(R2 / R1)-1| (see step 5) is greater than 0.15, the predetermined region on the surface of the silicon single crystal wafer into which Pt has been diffused is removed.

[0029] Here, the depth of the region to be removed can be set to the maximum depth at which |(R(d) / R1)-1| becomes greater than a predetermined value, where R(d) is the value of a depth d where resistivity R2 is.

[0030] The region where the resistivity R2 is different from the resistivity R1 can be removed by etching or polishing.

[0031] Step 7 of the method of the present invention is a step of determining the Pt concentration by the DLTS method for a Pt-diffused silicon single crystal wafer in which the ratio of resistivity R1 to resistivity R2 determined in step 5 is equal to or less than a predetermined value, or in which the ratio of resistivity R1 to resistivity R2 has become equal to or less than a predetermined value by removing a predetermined region of the surface in step 6.

[0032] In other words, if R1 and R2 are approximately the same, the Pt concentration can be measured directly by the DLTS method, and the vacancy concentration can be determined in the next step 8. On the other hand, if R1 and R2 are different (not approximately the same), for example, the depth profile of the resistivity of the sample (silicon single crystal wafer) after Pt diffusion is measured, and after removing areas in the substrate surface layer of the silicon single crystal wafer where the resistivity differs from R1, the Pt concentration is measured by the DLTS method, and the vacancy concentration is evaluated in the next step 8. One method for measuring the depth profile of resistivity is spreading resistance analysis (SRA).

[0033] Regarding whether R1 and R2 are comparable, taking into consideration the fact that slight changes in resistivity can be measured by the DLTS method and the variability in resistivity measurements, it is desirable to determine that R1 and R2 are comparable if |(R2 / R1)-1| ≦ 0.15, and that R1 and R2 are different if |(R2 / R1)-1| > 0.15. That is, using |(R2 / R1)-1| as the reference, it can be determined that R1 and R2 are comparable if the value of |(R2 / R1)-1| is 0.15 or less. On the other hand, if |(R2 / R1)-1| is greater than 0.15, it is determined that R1 and R2 are not comparable but are different, and it is preferable to remove a predetermined region on the surface of the silicon single crystal wafer into which Pt was diffused in step 3.

[0034] Step 8 of the method of the present invention is a step of estimating the vacancy concentration of the silicon single crystal wafer from the Pt concentration determined by the DLTS method.

[0035] When determining the Pt concentration by DLTS for a Pt-diffused silicon single crystal wafer in which the ratio of resistivity R1 to resistivity R2 is equal to or less than a predetermined value by removing a predetermined region on the surface of the silicon single crystal wafer in step 6, the DLTS method can be performed as follows: After measuring the depth profile of resistivity R2 in step 4, the ratio of R1 to R2 is determined in step 5, and if it is determined to be greater than the predetermined value in step 6, the region in the substrate surface layer of the silicon single crystal wafer whose resistivity is different from R1 is removed, and then the Pt concentration C is determined by DLTS in step 7. Pt In step 8, the obtained Pt concentration C Pt Using the following equation, the vacancy concentration C V(t=0) can be obtained. C V(t=0) =(1+C * V / C * Pt )C Pt (where C * V , C * Pt : Equilibrium concentration of vacancies and Pt at the Pt diffusion temperature) (H. Zimmermann and H. Ryssel, Phys. Rev. B 44(1991)9064.).

[0036] In this case, if we substitute the value reported by Zimmermann for the equilibrium concentration, the relationship between the vacancy concentration and the substitutional Pt concentration becomes C V(t=0) =3.1C Pt This becomes: [Example]

[0037] EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0038] [Example 1] The oxygen concentration of wafers (silicon single crystal wafers) cut from n-type 200 mm diameter silicon single crystal ingots grown by the FZ method was measured by FT-IR (Step 1). As a result, the oxygen concentration was found to be below the detection limit (~0 ppma). Because the oxygen concentration was less than 5 ppma, the resistivity R1 of the silicon single crystal wafer was measured using the four-probe method without donor killer heat treatment, and was found to be 76 Ω·cm (Step 2).

[0039] Then, as a Pt diffusion treatment, a Pt solution with a Pt concentration of 100 ppm, prepared by diluting an atomic absorption standard solution with pure water, was applied to the surface of the silicon single crystal wafer by spin coating, and then heat treatment was carried out at 650°C for 9 hours in a nitrogen atmosphere (step 3).

[0040] The resistivity of the Pt-diffused silicon single crystal wafer was measured using the four-probe method, and the resistivity R2 was found to be 14,620 Ω·cm (Step 4). As a result, |(R2 / R1)-1| = 191 (Step 5). In other words, |(R2 / R1)-1| > 0.15.

[0041] Therefore, a spreading resistance analysis was carried out on the silicon single crystal wafer, and it was found that the resistivity was significantly different from 76 Ω·cm in the region of the silicon single crystal wafer from the substrate surface to a depth of approximately 100 μm (see Figure 2). Therefore, 100 μm from the substrate surface of the silicon single crystal wafer was removed by mixed acid etching (step 6). After that, when DLTS measurement was carried out on the silicon single crystal wafer from which the top 100 μm had been removed (step 7), a peak due to substitutional Pt, which was proportional to the vacancy concentration, was detected (see the solid line "After removal" in Figure 3). Furthermore, from this peak, it was possible to determine the concentration C Pt is 1.2 x 10 13 cm -3 (Fig. 3) The substitutional Pt concentration C Pt and vacancy concentration C V(t=0) The relation C V(t=0) =3.1C Pt Therefore, the vacancy concentration C V(t=0) is 3.7 x 10 13 cm -3 It was estimated that (Step 8).

[0042] [Example 2] The oxygen concentration of a wafer (silicon single crystal wafer) sliced ​​from an n-type silicon single crystal ingot of 200 mm diameter, different from that of Example 1, grown by the FZ method, was measured by FT-IR (step 1). As a result, the oxygen concentration was found to be below the lower detection limit (up to 0 ppma). Because the oxygen concentration was less than 5 ppma, the resistivity R1 of the silicon single crystal wafer was measured by the four-probe method without donor killer heat treatment, and was found to be 76 Ω cm (step 2).

[0043] Then, as a Pt diffusion treatment, a Pt solution with a Pt concentration of 100 ppm, prepared by diluting an atomic absorption standard solution with pure water, was applied to the surface of the silicon single crystal wafer by spin coating, and then heat treatment was carried out at 650°C for 9 hours in a nitrogen atmosphere (step 3).

[0044] When the resistivity of the Pt-diffused silicon single crystal wafer was measured using the four-probe method, the resistivity R2 was found to be 82 Ω·cm (step 4). As a result, |(R2 / R1)-1| = 0.08 (step 5). In other words, |(R2 / R1)-1| ≦ 0.15. Therefore, when the Pt concentration was measured directly using the DLTS method (without performing step 6), a spectrum was obtained without any problems, and the Pt concentration C Pt is 4.0 x 10 13 cm -3 (Step 7). Substitutional Pt concentration C Pt and vacancy concentration C V(t=0) The relation C V(t=0) =3.1C Pt Therefore, the vacancy concentration C V(t=0) is 1.2 x 10 14 cm -3 It was estimated that (Step 8).

[0045] (Considerations of Examples 1 and 2) The vacancy concentrations (∝Pt concentration) obtained in Examples 1 and 2 are roughly equivalent to the values ​​reported in a previous study investigating the vacancy concentration of FZ crystals using the Pt diffusion method (H. Zimmermann and R. Falster, Appl. Phys. Lett. 60(1992)3250.).

[0046] [Example 3] The oxygen concentration of wafers (silicon single crystal wafers) cut from n-type 200 mm diameter silicon single crystal ingots grown by the CZ method was measured using FT-IR (Step 1). The result was an oxygen concentration of 15 ppma. Because the oxygen concentration was above 5 ppma, the silicon single crystal wafers were subjected to a donor killer heat treatment at 650°C for 20 min in a nitrogen atmosphere (Step 1). The resistivity R1 of these silicon single crystal wafers was measured using the four-probe method and was found to be 23.4 Ω cm (Step 2).

[0047] Then, as a Pt diffusion treatment, a Pt solution with a Pt concentration of 100 ppm, prepared by diluting an atomic absorption standard solution with pure water, was applied to the surface of the silicon single crystal wafer by spin coating, and then heat treatment was carried out at 650°C for 9 hours in a nitrogen atmosphere (step 3).

[0048] When the resistivity of the Pt-diffused silicon single crystal wafer was measured using the four-probe method, the resistivity R2 was found to be 24.1 Ω·cm (step 4). As a result, |(R2 / R1)-1| = 0.03 (step 5). In other words, |(R2 / R1)-1| ≦ 0.15. Therefore, when the Pt concentration was measured directly using the DLTS method (without performing step 6), a spectrum was obtained without any problems, and the Pt concentration C Pt is 1.1 x 10 12 cm -3 (Step 7). Substitutional Pt concentration C Pt and vacancy concentration C V(t=0) The relation C V(t=0) =3.1C Pt Therefore, the vacancy concentration C V(t=0) is 3.4 x 10 12 cm -3 It was estimated that (Step 8).

[0049] (Comparative study of Example 3 with Examples 1 and 2) The fact that the vacancy concentration in Example 3 is lower than in Examples 1 and 2 is consistent with the fact that the vacancy concentration decreases as the oxygen concentration increases, since vacancies are consumed by oxygen precipitation during the cooling process during crystal growth.

[0050] [Comparative Example 1] In Example 1, DLTS measurement was performed without removing 100 μm from the substrate surface of the silicon single crystal wafer. That is, even though the ratio of resistivity R1 to resistivity R2 (|(R2 / R1)-1|) was greater than a predetermined value (here, 0.15), step 6 was not performed and step 7 was performed. As a result, a peak due to substitutional Pt used in evaluating vacancy concentration was not detected (see the dashed line "before removal" in Figure 3). The fact that a peak was detected on the negative side of the trap density in the dashed line "before removal" in Figure 3 is thought to mean that minority carriers were generated by Pt diffusion.

[0051] (Comparative Consideration of Comparative Example 1 and Example 1) On the other hand, when a 100 μm region was removed from the substrate surface of the silicon single crystal wafer in Example 1 in which resistivity had changed, Pt was detected, which shows that Pt cannot be detected unless the surface layer region of the wafer in which resistivity had greatly changed is removed after the Pt has diffused into the originally existing vacancies.

[0052] Comparative Example 2 When the resistivity R1 of the same silicon single crystal wafer as in Example 3 was measured by the four-probe method without performing the donor killer heat treatment (not satisfying the conditions of step 1), it was 9.7 Ω cm (step 2). In other words, even though the oxygen concentration of the silicon single crystal wafer to be measured was equal to or higher than the predetermined value (here, 5 ppma), the donor killer heat treatment of step 1 was not performed and the wafer moved on to the subsequent step.

[0053] Then, as a Pt diffusion treatment, a Pt solution with a Pt concentration of 100 ppm, prepared by diluting an atomic absorption standard solution with pure water, was applied to the surface of the silicon single crystal wafer by spin coating, and then heat treatment was carried out at 650°C for 9 hours in a nitrogen atmosphere (step 3).

[0054] The resistivity of the Pt-diffused silicon single crystal wafer was measured using the four-probe method, and the resistivity R2 was 23.9 Ω·cm (Step 4). As a result, |(R2 / R1)-1| = 1.46 (Step 5). In other words, |(R2 / R1)-1| > 0.15.

[0055] However, if the Pt concentration is measured by the DLTS method as it is, a spectrum can be obtained without any problems, and the Pt concentration C Pt is 1.3 x 10 12 cm -3 Concentrations equivalent to those in Example 3 were detected.

[0056] (Comparative Consideration of Comparative Example 2 and Example 3) The results of Comparative Example 2 above show that the donor killer effect is significantly affected by the Pt diffusion heat treatment, which is different from Example 3. Therefore, it is clear that the DLTS measurement cannot be correctly determined from the ratio of resistivity R1 to resistivity R2 unless the thermal donors are eliminated beforehand before measuring resistivity R1.

[0057] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention.

Claims

1. A method for evaluating a vacancy concentration in a silicon single crystal wafer, comprising: a step 1 of measuring the oxygen concentration of a silicon single crystal wafer to be measured, and performing donor killer heat treatment if the measured oxygen concentration is equal to or higher than a predetermined value; a step 2 of measuring the resistivity R1 of the silicon single crystal wafer; Step 3 of applying Pt to the surface of the silicon single crystal wafer and then performing a heat treatment to diffuse the Pt; a step 4 of measuring the resistivity R2 of the Pt-diffused silicon single crystal wafer; Step 5: determining the ratio of the resistivity R1 to the resistivity R2; a step 6 of removing a predetermined region of the surface of the silicon single crystal wafer into which the Pt has been diffused when the ratio of the resistivity R1 to the resistivity R2 obtained as described above is greater than a predetermined value; A step 7 of determining a Pt concentration by a DLTS method for the Pt-diffused silicon single crystal wafer in which the ratio of resistivity R1 to resistivity R2 determined in the step 5 is equal to or less than a predetermined value, or in which the ratio of resistivity R1 to resistivity R2 has become equal to or less than a predetermined value by removing a predetermined region of the surface in the step 6; a step 8 of estimating the vacancy concentration of the silicon single crystal wafer from the Pt concentration determined by the DLTS method; A method for evaluating the vacancy concentration of a silicon single crystal wafer, comprising the steps of:

2. 2. The method for evaluating the vacancy concentration of a silicon single crystal wafer according to claim 1, wherein the predetermined value of the oxygen concentration in step 1 is set to 5 ppma.

3. The method for evaluating a vacancy concentration in a silicon single crystal wafer according to claim 1 or 2, wherein the ratio of the resistivity R1 to the resistivity R2 obtained in step 5 is set to |(R2 / R1)-1|.

4. The method for evaluating a vacancy concentration in a silicon single crystal wafer according to claim 3, wherein in step 6, if the value of |(R2 / R1)-1| is greater than 0.15, a predetermined region of the surface of the silicon single crystal wafer into which the Pt has been diffused is removed.

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