JP7310727B2 - Oxygen concentration measurement method in silicon sample - Google Patents

Description

The present invention relates to a method for measuring oxygen concentration in a silicon sample.

Silicon wafers used as substrates for power devices and CIS (CMOS image sensors) are required to have a long lifetime, and low oxygen content is required to avoid shortening the lifetime. For example, in power devices, FZ silicon wafers manufactured by the floating zone (FZ) method, which is capable of lowering oxygen than the Czochralski (CZ) method, are often used. Further, as a substrate for CIS, an epitaxial wafer obtained by depositing a low-oxygen epitaxial layer on a CZ silicon wafer grown by the CZ method is often used. Accurately measuring the oxygen concentration of such low-oxygen wafers is very important.

Conventional oxygen concentration measurement methods include the FT-IR method (Fourier transform infrared spectroscopy) and the SIMS method (secondary ion mass spectrometry), but these methods detect when the oxygen concentration falls below a certain value. Sensitivity worsens. The detection lower limit is 0.07 (ppma-JEITA) for the FT-IR method and 0.02 (ppma) for the SIMS method.

Here, as a method for measuring the impurity concentration in a silicon wafer with high sensitivity, there is a DLTS method (transient capacitance spectroscopy). For example, in Patent Document 1, Ec is the level at the lower end of the conduction band formed on a silicon wafer by electron beam irradiation, and the level density of Ec-0.42 eV is detected by the DLTS method, and this level density is used as an index. A carbon concentration measuring method is disclosed.

Next, the DLTS method will be described. In the DLTS method, for example, a metal electrode forming a Schottky junction is formed on the silicon sample surface, and a metal electrode having an ohmic junction is formed on the back surface. Then, after applying a reverse bias between the two electrodes to expand the depletion layer, for example, a forward pulse is applied to inject carriers into the impurity level in the depletion layer and release the carriers from the impurity level. The process is evaluated as capacitance change. Since the capacitance change peaks at a temperature corresponding to the energy level formed by the impurity, the impurity level density can be calculated from the capacitance change at the peak position. The method of injecting carriers into the depletion layer by manipulating the voltage in this manner is the most common technique.

JP 2018-139242 A

Takikawa et al., Transactions of the Institute of Electronics and Communication Engineers C 64 (1), P. 32-38, 1981

As described above, there are FT-IR method and SIMS method as methods for measuring oxygen concentration in silicon wafers. 02 (ppma), and there was a problem that the detection sensitivity was low at low oxygen concentrations.

As described above, Patent Document 1 discloses a carbon concentration measuring method in which the level density of Ec-0.42 eV is detected by the DLTS method and the level density is used as an index. No method of measurement is disclosed.

In principle, the voltage-controlled DLTS method for a Schottky diode structure can only capture the emission process of majority carriers (electrons for n-type, holes for p-type). In the case of a p-type silicon sample, only the electron trap level at which electrons are trapped can be evaluated, and only the hole trap level at which holes are trapped can be evaluated. Therefore, in the Schottky diode structure voltage-controlled DLTS method, the electron trap level in the n-type silicon sample can be detected, but the electron trap level in the p-type silicon sample cannot be detected.

If a pn junction is formed instead of a Schottky junction in a p-type silicon sample, the same rectifying property as the Schottky junction can be obtained even with a pn junction, and the emission process of electrons, which are minority carriers, can be captured. In order to form a pn junction, for example, an ion implantation process and a subsequent recovery heat treatment process are required, which is more complicated than the Schottky junction formation process of merely evaporating metal, and the throughput is much lower. Furthermore, since an unintended impurity level is formed in the ion implantation process, or the impurity level density including the target vacancies changes in the subsequent heat treatment process, a pn junction is formed instead of the Schottky junction. Therefore, it is not suitable for evaluating minute amounts of oxygen concentration.

As described above, in order to evaluate the electron (minority carrier) trap level in a p-type silicon sample by the voltage manipulation DLTS method, it is necessary to form a pn junction. The throughput is much lower than that of the DLTS method, and an unintended impurity level is also formed.

The present invention has been made to solve the above problems, and the oxygen concentration in a silicon sample, especially the oxygen concentration below the lower limit of detection in the FT-IR method and SIMS method, can be easily and highly sensitively evaluated. The purpose is to provide a method to

The present invention has been made to achieve the above object, and is a method for evaluating the oxygen concentration in a silicon sample, comprising irradiating the silicon sample with an electron beam or an ion beam other than oxygen to obtain a An impurity level containing vacancies is formed inside, the level density of the impurity level containing the vacancies is measured by an optical DLTS method, and based on the level density of the impurity level containing the vacancies, the A silicon sample oxygen concentration evaluation method for evaluating the oxygen concentration in a silicon sample is provided.

In this way, by measuring the impurity level density including vacancies reflecting the oxygen concentration in the silicon sample by the optical DLTS method and using it as an index, the oxygen concentration in the silicon sample, especially the FT-IR method and SIMS Oxygen concentration below the lower limit of detection in the method can be easily and highly sensitively evaluated.

At this time, it is preferable to use a silicon sample having a Schottky diode structure as the silicon sample.

A Schottky diode can be formed simply by vapor-depositing a metal on a silicon sample, which is convenient.

At this time, it is preferable to use a p-type silicon sample as the silicon sample and measure the electron trap level density of impurity levels including vacancies in the p-type silicon sample by the optical DLTS method.

Thus, when using a p-type silicon sample in which the majority carriers are holes, if the electron trap level, which is a level reflecting the oxygen concentration in the p-type silicon sample, is measured by the optical DLTS method, the p-type silicon The oxygen concentration in the sample can be evaluated with higher sensitivity.

At this time, the electron trap level density of the impurity level containing the vacancies is preferably Ec-0.17 eV, where Ec is the lower end level of the conduction band.

Such levels are related to vacancy-oxygen complexes, and by using this level density as an index, the oxygen concentration in the silicon sample can be evaluated with higher accuracy.

At this time, a silicon sample with a known oxygen concentration is prepared in advance, and the silicon sample with the known oxygen concentration is irradiated with an electron beam or an ion beam other than oxygen to include vacancies in the silicon sample with the known oxygen concentration. An impurity level is formed, the level density of the impurity level containing the vacancies is measured by an optical DLTS method, and the measured level density and the oxygen concentration in the silicon sample with the known oxygen concentration are calculated. It is preferable to obtain a correlation and evaluate the oxygen concentration in the silicon sample based on the correlation.

By obtaining the correlation between the level density measured by the optical DLTS method and the oxygen concentration in the silicon sample whose oxygen concentration is known, the absolute concentration of oxygen in the silicon sample can be calculated.

At this time, the oxygen concentration of the silicon sample whose oxygen concentration is known is preferably the oxygen concentration obtained by the SIMS method or the FT-IR method.

The SIMS method or the FT-IR method can accurately measure the oxygen concentration if the oxygen concentration in the silicon sample is equal to or higher than the lower limit of detection, and is therefore suitable for determining the correlation.

As described above, according to the method for evaluating the oxygen concentration in a silicon sample according to the present invention, the oxygen concentration in the silicon sample, particularly the oxygen concentration below the lower limit of detection in the FT-IR method and the SIMS method, can be easily and It can be evaluated with high sensitivity. In addition, a very small amount of oxygen concentration in a p-type silicon sample, which cannot be detected by the conventional voltage-controlled DLTS method, can be measured with high sensitivity.

1 is a flow chart showing an example of an oxygen concentration evaluation method in a silicon sample according to the present invention. 2 is a graph showing voltage-stimulated DLTS spectra and photo-DLTS spectra of p-type silicon samples subjected to electron beam irradiation treatment; 2 is a graph showing a voltage-controlled DLTS spectrum of an electron-beam irradiated n-type silicon sample and an optical DLTS spectrum of an electron-beam irradiated p-type silicon sample; 4 is a graph showing oxygen concentration dependence of electron trap levels E1 and E2 in a p-type silicon sample irradiated with an electron beam. 4 is a graph showing oxygen concentration dependence of hole trap levels H1 and H2 in a p-type silicon sample irradiated with an electron beam.

The present invention will be described in detail below, but the present invention is not limited to these.

As described above, there has been a demand for a simple and highly sensitive method for evaluating the oxygen concentration in a silicon sample, particularly the oxygen concentration below the lower limit of detection in the FT-IR method and SIMS method.

In addition, the present inventor detected an electron trap level, which is correlated with the oxygen concentration in a silicon sample, from a p-type silicon sample in which the majority carrier is a hole, and intensively investigated whether this could be used as an indicator of the oxygen concentration. bottom. More specifically, the optical DLTS method, which can evaluate minority carrier trap levels in Schottky junctions, was used to detect voids that correlated with the oxygen concentration in p-type silicon samples formed by particle beam irradiation such as electron beams. We investigated whether electron (minority carrier) trap levels including holes can be detected by the optical DLTS method.

As a result of intensive studies on the above problem, the inventors of the present invention found that among the impurity levels within the forbidden band width of silicon measured by the optical DLTS method, the higher the oxygen concentration in the silicon sample, the higher the level density. The present inventors have newly found that an electron trap level at which the .DELTA. That is, a method for evaluating the oxygen concentration in a silicon sample includes irradiating the silicon sample with an electron beam or an ion beam other than oxygen to form impurity levels including vacancies in the silicon sample, Oxygen concentration in a silicon sample for measuring the level density of impurity levels including holes by an optical DLTS method and evaluating the oxygen concentration in the silicon sample based on the level density of impurity levels including the vacancies The present inventors have found that the oxygen concentration in a silicon sample, especially the oxygen concentration below the lower limit of detection in the FT-IR method and SIMS method, can be easily and highly sensitively evaluated by the evaluation method, and have completed the present invention.

Description will be made below with reference to the drawings.

First, the optical DLTS method will be described. In the photo-DLTS method, the Schottky junction is irradiated with light instead of voltage operation, and both a large number and a small number of carriers (electron-hole pairs) are injected into the depletion layer. This is a method for evaluating carrier trap levels (Non-Patent Document 1). With this method, the minority carrier trap level can be evaluated without requiring a pn junction.

FIG. 1 is a flow chart showing an example of the oxygen concentration evaluation method in a silicon sample according to the present invention.

First, as in S1 of FIG. 1, a silicon sample whose oxygen concentration is to be evaluated is prepared. For example, a silicon sample cut from a silicon single crystal ingot pulled by the CZ method or the FZ method may be used, and the shape is not limited, and a silicon chip of several centimeters may be used. Specific examples include polished wafers, epitaxial wafers, annealed wafers, and the like.

Moreover, the silicon sample to be prepared is preferably a p-type silicon sample. When using a p-type silicon sample in which the majority carriers are holes, if the electron trap level, which is a level reflecting the oxygen concentration in the p-type silicon sample, is measured by the optical DLTS method, the oxygen in the p-type silicon sample Concentration can be evaluated with higher sensitivity. Although a p-type silicon sample will be described below as an example of a silicon sample, the present invention is not limited to this.

Next, as in S2 of FIG. 1, the p-type silicon sample is irradiated with an electron beam or a particle beam of an ion beam other than oxygen. When a silicon sample is subjected to ion implantation or electron beam irradiation, silicon at lattice positions is ejected, and vacancies and interstitial silicon are generated. known to It is also known that these impurity level densities strongly depend on the concentration of impurities (for example, concentrations of oxygen, carbon, etc.) in the silicon sample to be irradiated. Impurity levels including holes can be formed.

The electron beam irradiation dose is, for example, 5.0×10 ¹³ to 5.0×10 ¹⁵ /cm ² , and the ion beam dose is, for example, 1.0×10 ¹¹ to 1.0×10 ¹³ ( atoms/cm ² ). By setting both the electron beam dose and the ion beam dose within this range, it is possible to more effectively prevent problems such as failure to form the desired impurity levels due to too small dose and dose. In addition, it is possible to more effectively prevent the crystallinity from deteriorating due to the disturbance of the crystal lattice due to excessive irradiation or dose, which makes it impossible to detect the target impurity level. In the case of an oxygen ion beam, the irradiated oxygen ions affect the formation of the impurity level and affect the oxygen concentration to be evaluated. Therefore, an ion beam other than oxygen is used.

Next, as in S3 of FIG. 1, a Schottky diode structure is formed on the p-type silicon sample. Specifically, Schottky characteristics can be obtained by vapor-depositing, for example, Al on the surface of a p-type silicon sample. This Schottky characteristic has rectifying properties, and when a forward bias is applied, current flows, and when a reverse bias is applied, current does not flow and the depletion layer expands. In the DLTS method, the impurity level can be evaluated by injecting carriers into the impurity level in this depletion layer and monitoring the emission process.

The Schottky diode structure can be easily formed by simply evaporating a metal onto a silicon sample. The Schottky diode structure does not require a complicated process with a very low throughput. Furthermore, since it does not include processes such as ion implantation that unintentionally form impurity levels, or changes in impurity level density including vacancies that reflect the oxygen concentration, such as heat treatment, it is possible to minimize the presence of trace amounts of oxygen. Suitable for measuring concentration.

Next, as in S4 of FIG. 1, the impurity level including vacancies is measured using the optical DLTS method.

Here, the fact that the object to be measured can be a p-type silicon sample with a Schottky diode structure, and the reason why the optical DLTS method is used instead of the general voltage operation DLTS method in the present invention will be explained. Description will be made based on the range of possible impurity levels.

Unlike a pn junction, a Schottky diode is formed by a junction of a metal and a semiconductor (p-type silicon) and operates only with majority carriers (holes in p-type silicon). In the voltage-controlled DLTS method, after applying a reverse bias to the Schottky junction to widen the depletion layer, a forward pulse is applied to inject only the majority carriers into the impurity level in the depletion layer, and the reverse bias is applied again. The impurity level is evaluated by monitoring the emission process of majority carriers from the impurity level when the voltage is applied as a change in capacitance. Therefore, only majority carriers can be handled by the voltage manipulation DLTS method, and minority carriers (electrons in p-type silicon) cannot be handled. In other words, the Schottky diode structure voltage-controlled DLTS method can detect only the majority carrier impurity level, that is, only the hole trap level in the case of a p-type silicon sample. Thus, even if the voltage manipulation DLTS method is applied to a p-type silicon sample with a Schottky diode structure, the electron (minority carrier) trap level cannot be evaluated.

In contrast, the optical DLTS method used in the present invention forms electron-hole pairs ( injection), monitor the emission process of both electrons and holes, and evaluate the impurity level. For example, even in a p-type silicon sample with a Schottky diode structure, the electron trap level can be evaluated because the emission process of electrons, which are minority carriers, can be captured. As the light to be irradiated at this time, light having energy equal to or higher than the forbidden band width of silicon may be used, or light having energy equal to or lower than the forbidden band width may be used.

FIG. 2 shows, as an example, a voltage manipulated DLTS spectrum and a photoDLTS spectrum after electron beam irradiation treatment was applied to a p-type silicon sample at an acceleration voltage of 2 (MV) and a dose of 1.0×10 ¹⁵ /cm ^{2 .} It is a graph showing. The graph shows the majority carrier trap level as positive and the minority carrier trap level as negative. Only the positive hole trap levels H1 and H2 are detected in the normal voltage-controlled DLTS method. On the other hand, in the photo-DLTS method, negative electron trap levels E1 and E2 are detected in addition to the hole trap level of H2 detected in the normal voltage manipulation DLTS method.

Next, FIG. 3 shows the optical DLTS spectrum of the p-type silicon sample subjected to the electron beam irradiation treatment described above and the voltage-controlled DLTS spectrum of the n-type silicon sample subjected to the electron beam irradiation treatment under the same conditions. The peak positions of the n-type majority carrier (electron) trap levels E1 and E2 and the p-type minority carrier (electron) trap levels E1 and E2 are the same, which confirms the validity of the measurement by the optical DLTS method. showing. Thus, the optical DLTS method can detect the minority carrier trap level as well as the majority carrier trap level.

Next, the oxygen concentration dependence of these impurity levels will be described. As an example, in FIG. 4, p-type silicon samples with different oxygen concentrations were subjected to electron beam irradiation treatment at an acceleration voltage of 2 (MV) and an irradiation dose of 1.0×10 ¹⁵ /cm ² , and then obtained by the photo-DLTS method. Oxygen concentration dependence of E1 and E2 obtained. Here, Ec is the lower end level of the conduction band, E1 is Ec-0.17 eV, which is related to the oxygen-vacancy complex, and E2 is Ec-0.23 eV, which is the level related to the vacancy-vacancy complex. Both E1 and E2 show a positive correlation with the oxygen concentration, and it can be seen that both E1 and E2 can serve as indices for oxygen concentration evaluation. Among them, E1 has a better correlation coefficient than E2, so it is more preferable to use E1 as an index. The reason why E1 has a better correlation with oxygen concentration than E2 is that E1 (Ec-0.17 eV) is a vacancy oxygen complex and has the highest correlation with oxygen concentration in the silicon sample. be.

For comparison, FIG. 5 shows the oxygen concentration dependence of the level densities of H1 and H2 obtained by evaluating a p-type silicon sample of the same level as in FIG. 4 by the voltage manipulation DLTS method. It can be seen that neither H1 nor H2 has a correlation with the oxygen concentration. Therefore, the hole trap level in the p-type silicon sample cannot be used as an indicator of the oxygen concentration. It is necessary to detect the trap level E1 or E2.

Finally, as in S5 of FIG. 1, the oxygen concentration is evaluated using the impurity level E1 or E2 containing vacancies in the p-type silicon sample as an index. It can be determined that the lower the level density of both E1 and E2, the lower the oxygen concentration. Therefore, it is possible to evaluate the relationship between high and low oxygen concentrations among samples at a plurality of levels without using a calibration curve, which will be described later.

In addition, by obtaining the correlation between the level density measured by the optical DLTS method and the oxygen concentration in a silicon sample with a known oxygen concentration, it is possible to simply evaluate the relationship between high and low oxygen concentrations among multiple levels of silicon samples. Instead, the absolute concentration of oxygen in the silicon sample can be calculated. Specifically, for example, a silicon sample with a known oxygen concentration is prepared in advance, and an electron beam or an ion beam other than oxygen is irradiated to the silicon sample with the known oxygen concentration to create vacancies in the silicon sample with the known oxygen concentration. is formed, the level density of the impurity level containing vacancies is measured by the optical DLTS method, and the correlation between the measured level density and the oxygen concentration in the silicon sample whose oxygen concentration is known , and the oxygen concentration in the silicon sample can be evaluated based on the correlation. The oxygen concentration of the silicon sample whose oxygen concentration is known is preferably the oxygen concentration obtained by the SIMS method or the FT-IR method. The SIMS method and the FT-IR method can accurately measure the oxygen concentration in the silicon sample, and are therefore suitable for determining the correlation.

When comparing with the conventional FT-IR method or SIMS method, for example, from the level density of E1 and / or E2 measured by the optical DLTS method and the oxygen concentration obtained by the SIMS method or the FT-IR method , it is preferable to prepare a calibration curve as shown in FIG. By using this calibration curve, the level density measured by the optical DLTS method can be converted into the oxygen concentration obtained by the SIMS method or the FT-IR method. The SIMS method and the FT-IR method are suitable for creating a calibration curve because they can accurately measure the oxygen concentration as long as they are at or above the lower limit of detection. Moreover, as described above, since E1 has a better correlation with the oxygen concentration, it is more preferable to use E1 as an index.

The impurity level density detected by the optical DLTS method cannot be directly compared with the oxygen concentration of the conventional FT-IR method or SIMS method. , the absolute concentration can be calculated and compared.

As described above, by irradiating a silicon sample with an electron beam or an ion beam other than oxygen to form impurity levels containing vacancies and using the level density of the impurity levels measured by the optical DLTS method, silicon Oxygen concentration in a sample, especially oxygen concentration below the lower limit of detection in the FT-IR method and SIMS method, can be evaluated simply and with high sensitivity. In particular, even when measuring a p-type silicon sample in which the majority carriers are holes, the oxygen concentration can be measured with high sensitivity by using the minority carrier (electron) trap level density, which is correlated with the oxygen concentration, as an index. can be evaluated.

EXAMPLES The present invention will be specifically described below with reference to Examples, but these are not intended to limit the present invention.

(Example)
A total of four levels of p-type silicon samples 1, 2 and 3 with different oxygen concentrations pulled by the FZ method and p-type silicon sample 4 pulled by the CZ method were prepared. Next, the sample was irradiated with an electron beam at an acceleration voltage of 2 (MV) and a dose of 1.0×10 ¹⁵ /cm ² . Next, the oxide film on the surface was removed with hydrofluoric acid, aluminum was vapor-deposited on the surface as a Schottky electrode, and gallium was imprinted on the back surface as an ohmic electrode to form a Schottky diode structure. Next, the level densities of E1 (Ec-0.17 eV) and E2 (Ec-0.23 eV) were evaluated by the optical DLTS method. Also, the level density was converted to the oxygen concentration using the calibration curve of FIG. 4 prepared in advance.

Table 1 shows the oxygen concentration converted to the level density of E1 (Ec-0.17 eV) and E2 (Ec-0.23 eV) obtained by the optical DLTS method of the example, and the conventional method of Comparative Example 1 described later. is a table showing the results obtained by the SIMS method of Comparative Example 2 and the voltage-operated DLTS method of Comparative Example 2.

As a result of the example, as shown in Table 1, the level densities of E1 and E2 are both (low) sample 1<sample 2<sample 3<sample 4 (high), and the converted oxygen concentration has the same high-low relationship. became. It can be seen that the oxygen concentration in the silicon sample can be accurately evaluated regardless of whether E1 or E2 is used as the level density. At this time, when converted using the level density of E1 (Ec-0.17 eV) as the first index as described above, the sample 1 is 0.012 ppma, the sample 2 is 0.027 ppma, and the sample 3 is 0. .26 ppma, and sample 4 was found to be 13.7 ppma.

(Comparative example 1)
Subsequently, in order to verify the results of the example, the oxygen concentration of a silicon sample having the same level as that of the example was measured by the SIMS method. As a result, the results are as shown in Table 1, and the oxygen concentration is (low) sample 1<sample 2<sample 3<sample 4 (high).

Comparing the example and comparative example 1, samples 2, 3, and 4 have the same oxygen concentration as those of the example and comparative example 1, which indicates the validity of the present invention. In addition, the detection limit of sample 1 was 0.02 ppma or less, but in the above example, it was found to be 0.012 ppma, so the method of the present invention detects a trace amount of oxygen concentration that cannot be detected by the conventional SIMS method. It was shown that it can be evaluated with

(Comparative example 2)
Furthermore, in order to verify the superiority of the optical DLTS method of the example, only the hole trap level, which is the majority carrier, was evaluated by the voltage-controlled DLTS method for silicon samples of the same level as the example. As a result, only H1 and H2 shown in FIG. 2 were detected, and an impurity level correlated with the oxygen concentration was not detected, so the oxygen concentration could not be evaluated.

As described above, according to the method for evaluating the oxygen concentration in a silicon sample according to the present invention, the oxygen concentration in the silicon sample, particularly a trace amount of oxygen concentration below the lower limit of detection in the FT-IR method or the SIMS method, can be easily and It was shown that it can be evaluated with high sensitivity. In addition, it was shown that a very small amount of oxygen concentration in a p-type silicon sample, which cannot be detected by the conventional voltage-controlled DLTS method, can be evaluated and calculated with high sensitivity.

In addition, this invention is not limited to the said embodiment. The above-described embodiment is an example, and any device having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same effect is the present invention. included in the technical scope of

Claims (6)

A method for evaluating oxygen concentration in a silicon sample, comprising:
An impurity level including vacancies is formed in the silicon sample by irradiating the silicon sample with an electron beam or an ion beam other than oxygen, and the level density of the impurity levels including the vacancies is measured by an optical DLTS method. and evaluating the oxygen concentration in the silicon sample based on the level density of impurity levels containing the vacancies. 2. The method for evaluating an oxygen concentration in a silicon sample according to claim 1, wherein a silicon sample having a Schottky diode structure is used as said silicon sample. 2. A p-type silicon sample is used as said silicon sample, and an electron trap level density of an impurity level containing vacancies in said p-type silicon sample is measured by said optical DLTS method. 2. The method for evaluating the oxygen concentration in the silicon sample according to 2 above. 4. The method according to claim 3, wherein the electron trap level density of the impurity level containing the vacancies is an electron trap level density of Ec-0.17 eV, where Ec is the lower end level of the conduction band. method for evaluating oxygen concentration in silicon samples. A silicon sample with a known oxygen concentration is prepared in advance, and the silicon sample with the known oxygen concentration is irradiated with an electron beam or an ion beam other than oxygen to obtain an impurity level including vacancies in the silicon sample with the known oxygen concentration. is formed, and the level density of the impurity level containing the vacancies is measured by the optical DLTS method, and the correlation between the measured level density and the oxygen concentration in the silicon sample in which the oxygen concentration is known is calculated 5. The method for evaluating oxygen concentration in a silicon sample according to claim 1, wherein the oxygen concentration in the silicon sample is evaluated based on the correlation. 6. The method for evaluating oxygen concentration in a silicon sample according to claim 5, wherein the oxygen concentration of the silicon sample whose oxygen concentration is known is obtained by SIMS method or FT-IR method.

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