JP4147453B2 - Nitrogen concentration measurement method and calculation method of proportional conversion factor for nitrogen concentration measurement - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for measuring a nitrogen concentration and a method for calculating a proportional conversion coefficient for measuring nitrogen concentration . For example, the present invention is characterized by a method for measuring a nitrogen concentration in a silicon wafer cut out from a silicon ingot pulled up by the Czochralski method. The present invention relates to a method for measuring nitrogen concentration and a method for calculating a proportional conversion coefficient for measuring nitrogen concentration .
[0002]
[Prior art]
Silicon devices are manufactured using a silicon wafer cut out from a silicon ingot pulled up by the Czochralski method. At that time, the concentration of impurities such as nitrogen in the silicon wafer to be used is known in advance. It is necessary to keep.
[0003]
In particular, in recent years, nitrogen has been doped to reduce defects caused by voids such as void defects, COP, or LSTD, and to enhance gettering action by promoting oxygen precipitation. Need to control.
[0004]
Therefore, conventionally, a wafer manufacturer was requested to supply a wafer having a desired nitrogen concentration, and a nitrogen concentration test measurement for confirming the supplied wafer was performed.
[0005]
In this case, if a SIMS (secondary ion mass spectrometer) is used, it is possible to measure the nitrogen concentration precisely, but there is a problem that the measurement is expensive, and therefore a simple measurement method using infrared rays is required. It has been.
[0006]
Therefore, the present inventors have already developed a technique for quantifying the impurity nitrogen concentration in the silicon crystal pulled up by the Czochralski method by infrared absorption measurement (see Japanese Patent Application No. 2001-259446 if necessary). Therefore, the outline of the method is shown below.
[0007]
First, when infrared absorption measurement is performed on the supplied nitrogen-added CZ-Si crystal sample, infrared absorption line peaks due to two types of nitrogen-related defects are observed.
One of these two types of defects is a defect consisting of impurity nitrogen between the lattices of silicon atoms and impurity nitrogen between the lattices of silicon atoms within the fourth proximity of the impurity nitrogens, so-called NN pairs. This is a defect having an absorption peak at a wave number of 963 cm ⁻¹ .
The “fourth adjacent silicon atom from the impurity nitrogen” means a silicon atom bonded through three connectors counted from the nearest Si lattice position of one N of the NN pair.
[0008]
Another has defects consisting of impurity oxygen is between N-N from the pair of silicon atoms is within a fourth proximity grating, the absorption peak at a wavenumber of 996cm ^-1 and 1026cm ^-1 which so-called N-O complex It is a defect.
[0009]
When the present inventors hold a nitrogen-added CZ-Si crystal sample at a temperature higher than 600 ° C. for about 2 hours or more, the defect reaction between the N—N pair and the N—O complex reaches a thermal equilibrium at this time scale. We have succeeded in finding a quasi-thermal equilibrium state where the density is constant.
[0010]
In this quasi-thermal equilibrium state, the density ratio of the N—N pair and the N—O complex is also constant, so that the sample reaches a quasi-thermal equilibrium state and has at least wave numbers of 963 cm ⁻¹ , 996 cm ⁻¹ , and 1026 cm ⁻¹ . By obtaining the intensity of the absorption peak appearing at one position, the intensity of the three peaks can be determined.
The total impurity nitrogen concentration can be determined by using a proportional conversion coefficient prepared in advance.
[0011]
As described above, when the absorption due to impurity atoms is evaluated by infrared absorption measurement, it is common to use a difference spectrum from a crystal containing impurities, using a crystal containing no impurities as a reference.
[0012]
For example, the well-known quantification of impurity oxygen in CZ-Si uses a silicon crystal prepared by a floating zone method that does not contain oxygen as a reference. In general, an infrared absorption difference spectrum with a crystal containing impurity nitrogen is used with a sample containing no nitrogen as a reference.
[0013]
[Problems to be solved by the invention]
However, infrared absorption lines due to the nitrogen-related defects, such as N-N pair or N-O complex, 963cm ^-1 as described above, 996cm ^-1 and has a peak at 1026cm ^-1, which is at room temperature This corresponds to the base of large absorption of interstitial oxygen having a peak at 1106 cm ⁻¹ .
[0014]
In addition, since the concentration of impurity nitrogen is a few percent of impurity oxygen and the absorption is negligible, when obtaining the infrared absorption difference spectrum, not only the oxygen concentration with the reference but also the sample thickness and the amount of impurity doping other than nitrogen are aligned. However, there is a problem that there is a slight difference between them and the absorption of nitrogen cannot be detected just by changing the baseline. Therefore, the biggest challenge is how to align factors other than nitrogen in the measurement sample and reference. is there.
[0015]
The most important thing in practical use is how accurately a nitrogen-added wafer having a thickness of 1 mm or less can be measured.
This is because, in addition to the concentration of nitrogen contained in silicon being smaller than the concentration of other impurities, if the thickness of the sample to be measured is thin, such as a wafer, impurities contained in the wafer through which infrared light passes This is because the absolute amount of nitrogen is reduced, so that the peak intensity of infrared absorption due to impurity nitrogen is also reduced. Therefore, the demand for the reference becomes more severe.
[0016]
The only way to eliminate such inconsistencies in the oxygen concentration, sample thickness, and impurity doping amount other than nitrogen in the measurement crystal and reference crystal is to use the same crystal for both the measurement sample and the reference crystal. If the same sample is used, even the impurity nitrogen concentration matches, so there is a problem that it does not play a role in determining the nitrogen concentration.
[0017]
Accordingly, an object of the present invention is to precisely measure the specific impurity concentration in a semiconductor wafer by a simple infrared absorption difference spectrum without requiring a separate reference.
[0018]
[Means for Solving the Problems]
Here, means for solving the problems in the present invention will be described.
In order to achieve the above object, according to the present invention, in the nitrogen concentration measurement method, the first step of bringing the silicon crystal into a quasi-thermal equilibrium state at the first heating temperature, and the first infrared absorption of the silicon crystal A second step of measuring a spectrum; a third step of bringing the silicon crystal into a quasi-thermal equilibrium state at a second heating temperature; and a fourth step of measuring a second infrared absorption spectrum of the silicon crystal. A step, a fifth step of obtaining an infrared absorption difference spectrum between the first infrared absorption spectrum and the second infrared absorption spectrum, obtaining an intensity of an absorption peak corresponding to a defect caused by nitrogen, and the absorption peak. And a sixth step of determining a nitrogen concentration in the silicon crystal based on the strength of the silicon crystal.
[0019]
If heat treated at a specific annealing temperature becomes quasi thermal equilibrium, the peak intensity ratio corresponding to the defects due to nitrogen, with constant regardless of the nitrogen concentration, the peak intensity in each heat treatment temperature nitrogen concentration For example, by heating one or more infrared absorption measurement silicon crystals cut out from one silicon mother crystal at different temperatures, the concentration of nitrogen can be reduced without requiring a separate reference. Can be determined .
[0020]
In this case, the same silicon crystal may be heated twice at different temperatures, or two silicon crystals may be heated at different temperatures, and when the same silicon crystal is used, Since the original impurities are the same, the background can be accurately removed, and when two silicon crystals are used, heat treatment can be performed simultaneously using a plurality of heat treatment apparatuses. Therefore, the measurement time can be shortened.
[0021]
The heat treatment time is within the range of the measurement error of the infrared absorption difference spectrum in which the defect form and density caused by nitrogen are within a range of measurement error, for example, 2 hours to 15 hours, more preferably 2 hours to 8 hours. It is desirable.
If the time exceeds 15 hours, the internal structure changes due to oxygen precipitation, making it difficult to measure with high accuracy.
[0022]
Further, as such a silicon mother crystal, a silicon crystal containing impurity oxygen, particularly a silicon ingot pulled up by the Czochralski method is typical, and an impurity to be measured is nitrogen. .
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Here, the method for measuring the added nitrogen concentration of the silicon wafer according to the embodiment of the present invention will be described. Before that, the principle of measuring the added nitrogen concentration will be described with reference to FIGS.
See Figure 1. Figure 1, the inventors have found, 963cm ^-1 of silicon crystal of impurity nitrogen concentration of ^{3.2 × 10 15 cm -3, 996cm} -1, and the peak at 10 18 cm ^-1 It is a figure which shows the heat treatment temperature dependence of the absorbance when the nitrogen related defect which has has reached the quasi-thermal equilibrium state.
Note that the impurity concentration in this case is accurately determined in advance by SIMS (secondary ion mass spectrometry) or radiochemical analysis.
[0024]
As shown, when the heat treatment prescribed time to fix the heat treatment temperature, since the reaction of the nitrogen-related defects reaches a quasi-thermal equilibrium, the density of the defects of 963cm ^-1, 996cm ^-1, and, l0 18 cm ^-1 The peak intensity ratio proportional to is constant regardless of the impurity nitrogen concentration.
[0025]
Therefore, when attention is paid to any one of the peaks at 963 cm ⁻¹ , 996 cm ⁻¹ , and 10 18 cm ⁻¹ , the difference in absorbance at different heat treatment temperatures is uniquely determined according to the impurity nitrogen concentration.
[0026]
2 FIG. 2 shows a quasi-thermal equilibrium state in which five silicon chips cut out from one CZ-silicon wafer are heat-treated at 600 ° C., 700 ° C., 750 ° C., 800 ° C., and 900 ° C., respectively. Is a difference spectrum with a silicon chip heat-treated at 600 ° C. as a reference, and a peak is observed in the difference spectrum at 963 cm ⁻¹ , and particularly a silicon chip heat-treated at 800 ° C. It will be understood that the difference between is the largest.
In addition, the underline of the straight line in each curve is a line for determining the magnitude | size of the peak of 963 cm < ^-1 >.
[0027]
With the above as a background, the impurity nitrogen concentration measured in advance by SIMS of nitrogen-added CZ-silicon crystal A is N _A, and here, for example, an N—N pair having a peak at 963 cm ⁻¹ where a peak is seen in the difference spectrum Focus only on the resulting absorption.
[0028]
First, when the silicon crystal A is heat treated at 600 ° C. to reach a quasi-thermal equilibrium state, the crystal is used as a reference crystal, and then subjected to a heat treatment at 800 ° C. for 2 hours where the difference spectrum becomes the largest to reach a quasi-thermal equilibrium state. The difference crystal with respect to the reference crystal is measured using the crystal obtained as a measurement crystal.
[0029]
In this case, the true absolute value of the absorbance of each of the measurement crystal and the reference crystal is unknown, and only the difference between the absorbances is known.
This is represented by α _A (800-600).
[0030]
However, since the absolute value α _A (800-600) of the absorbance is proportional to the impurity nitrogen concentration contained in the silicon crystal, the relationship of the following equation is obtained using a certain proportional conversion factor κ and the impurity nitrogen concentration N _A. It is done.
_{α A (800-600) = κ ·} N A ··· (1)
[0031]
Therefore, α _A (800-600) is determined by infrared absorption measurement, and the total impurity nitrogen concentration N _A is measured by secondary ion mass spectrometry or activation analysis as described above. Is uniquely determined.
Note that the transition to the quasi-thermal equilibrium state due to the heat treatment of defects derived from such impurity nitrogen is determined by the thermodynamic requirements, so the proportional conversion factor κ is not limited to the growth method but is a silicon crystal containing oxygen. Is common.
[0032]
Next, the silicon crystal B whose impurity nitrogen concentration is unknown is subjected to a heat treatment at 600 ° C. to reach a quasi-thermal equilibrium state, and then infrared absorption measurement is performed as a reference crystal, and the absorbance α of the 963 cm ⁻¹ peak including the background α _{Get 600} .
[0033]
Next, the same silicon crystal B was subjected to a heat treatment at 800 ° C. to reach a quasi-thermal equilibrium state, and then infrared absorption measurement was performed as a measurement crystal to obtain an absorbance α ₈₀₀ of a 963 cm ⁻¹ peak including the background. α _B (800−600) = α ₈₀₀ −α ₆₀₀ is obtained.
[0034]
As described above, the proportional conversion coefficient κ for the difference in absorbance α (800−600) between the quasi-thermal equilibrium state by the heat treatment at 600 ° C. and the quasi-thermal equilibrium state by the heat treatment at 800 ° C. is constant regardless of the crystal. From equation (1)
α _B (800−600) = κ · N _B
It becomes.
[0035]
Therefore, impurity nitrogen concentration N _B of the silicon crystal B has already a proportional conversion factor κ as determined by silicon crystal A which had been accurately measured impurity nitrogen concentration by SIMS or the like, in a silicon crystal B of impurity nitrogen concentration is unknown From the measured difference infrared absorbance α _B (800-600),
N _B = α _B (800−600) / κ (2)
As required.
[0036]
In this way, once the accurate impurity nitrogen concentration is measured by SIMS etc. once and the proportional conversion coefficient κ is obtained, the impurity nitrogen concentration contained in various silicon crystals is accurately determined only by simple infrared absorption measurement. It becomes possible to evaluate to.
[0037]
Further, since the same sample is heat-treated a plurality of times, the difference between the measurement sample and the reference as described in the problem to be solved by the above invention does not substantially occur.
Although the impurity concentration slightly changes due to out-diffusion or the like by heat-treating the same sample a plurality of times, there is no problem because the change in absorbance due to the change is smaller than the measurement error of the infrared absorption difference spectrum.
[0038]
Based on the above measurement principle, the first embodiment of the present invention will be described next with reference to FIG.
FIG. 3 is a flowchart of the silicon crystal evaluation method according to the first embodiment of the present invention.
(1) One infrared absorption measurement sample piece is cut out from one silicon wafer cut out from a silicon ingot pulled up by the Czochralski method.
[0039]
Then
(2) The cut sample piece for infrared absorption measurement is heat-treated at 600 ° C. in a nitrogen atmosphere for 2 to 15 hours, for example, 2 hours.
In this heat treatment, the sample piece for infrared absorption measurement reaches a quasi-thermal equilibrium state.
Then
(3) An infrared absorption spectrum is obtained for the sample piece for infrared absorption measurement subjected to heat treatment.
[0040]
Then
(4) The same infrared absorption measurement sample piece is heat-treated at 800 ° C. in a nitrogen atmosphere for 2 to 15 hours, for example, 2 hours.
In this heat treatment, the sample piece for infrared absorption measurement reaches another quasi-thermal equilibrium state again.
Then
(5) An infrared absorption spectrum is obtained again for the sample piece for infrared absorption measurement subjected to the second heat treatment.
[0041]
Then
(6) Absorbance α (800-600) in a difference spectrum at a peak of 963 cm ⁻¹ between an infrared absorption spectrum obtained after heat treatment at 600 ° C. and an infrared absorption spectrum obtained after heat treatment at 800 ° C. is determined.
[0042]
Then
(7) For silicon chips with a known impurity nitrogen concentration, using the proportional conversion coefficient κ relating to the difference absorbance α (800-600) obtained by heat treatment at 800 ° C. and 600 ° C. obtained in advance, Based on the nitrogen concentration N,
N = α (800−600) / κ
Asking.
[0043]
As described above, in the first embodiment of the present invention, the same chip is heat-treated twice, and the infrared absorption spectrum acquired by the first heat-treatment is used as a reference, so that a separate reference chip is required. Therefore, since the oxygen concentration, the concentration of impurities other than nitrogen, and the thickness of the chip are constant, there is no problem in using a separate reference chip as in the prior art.
[0044]
Next, a second embodiment of the present invention will be described with reference to FIG.
FIG. 4 is a flowchart of the silicon crystal evaluation method according to the second embodiment of the present invention.
(1) Two infrared absorption measurement sample pieces are cut out from one silicon wafer cut out from a silicon ingot pulled up by the Czochralski method.
[0045]
Then
(2) The two cut infrared specimens for infrared absorption measurement were each subjected to a different heat treatment apparatus, and one was subjected to heat treatment in a nitrogen atmosphere at 600 ° C. for 2 to 15 hours, for example, 2 hours, for quasi-thermal equilibrium. The other infrared absorption measurement sample piece is subjected to a heat treatment in a nitrogen atmosphere at 800 ° C. for 2 to 15 hours, for example, 2 hours to reach another quasi-thermal equilibrium state.
[0046]
Then
(3) An infrared absorption spectrum is obtained for each of the two infrared absorption measurement sample pieces that have been heat-treated.
Then
(4) The absorbance α (800-600) in the difference spectrum at the 963 cm ⁻¹ peak of the two infrared absorption spectra is determined.
[0047]
Then
(5) For a silicon chip with a known impurity nitrogen concentration, using the proportional conversion coefficient κ relating to the difference absorbance α (800-600) obtained by heat treatment at 800 ° C. and 600 ° C. obtained in advance, Based on the nitrogen concentration N,
N = α (800−600) / κ
Asking.
[0048]
As described above, in the second embodiment of the present invention, since two chips cut out from the same wafer are heat-treated at the same time, the time required for the heat treatment can be reduced to one time. It can be shortened.
Although the oxygen concentration and the concentration of impurities other than nitrogen in the two chips may be slightly different, there is no substantial problem by cutting out the two chips from areas adjacent to each other.
[0049]
While the embodiments of the present invention have been described above, the present invention is not limited to the configurations and conditions described in the embodiments, and various modifications can be made.
For example, in each of the above embodiments, a difference spectrum between an infrared absorption spectrum after heat treatment at 800 ° C. and an infrared absorption spectrum after heat treatment at 600 ° C. is used, but a difference spectrum between other temperatures is used. It is good.
[0050]
In each of the above embodiments, the reference is an infrared absorption spectrum after heat treatment at 600 ° C., but the reference is not necessarily an infrared absorption spectrum after heat treatment at 600 ° C., for example, after the heat treatment at 700 ° C. An infrared absorption spectrum may be used. In that case, the second heat treatment may be performed at 700 ° C. or higher.
However, in that case, it is necessary to set the heat treatment temperature of the reference to 700 ° C. when κ is acquired in advance.
[0051]
In the second embodiment, heat treatment is simultaneously performed using two heat treatment apparatuses. However, a temperature gradient may be provided in the same heat treatment furnace, and the heat treatment may be performed simultaneously in the same heat treatment furnace. This makes it possible to use only one heat treatment apparatus.
[0052]
Alternatively, the heat treatment may be performed separately using the same heat treatment furnace. In this case, variations in the impurity concentrations of the two chips are somewhat problematic, but conversely, the first embodiment As compared with the form, it is not affected by the fluctuation of the impurity concentration due to the out diffusion due to the difference in the heat treatment time.
[0053]
Further, in the above embodiments, although the peak at 963cm ^-1 measured, it is permissible using a peak of 996cm ^-1 and 1018 cm ^-1.
[0054]
In each of the above embodiments, the CZ-silicon crystal is a measurement target, but is not limited to the CZ-silicon crystal, and includes at least oxygen grown by another growth method and added with nitrogen. If it is a silicon crystal, a similar quasi-thermal equilibrium state exists, so that it is applied.
[0055]
Furthermore, oxygen does not necessarily need to be included. If attention is paid to the NN pair, the present invention can also be applied to an ingot grown by a floating zone method that substantially does not contain oxygen.
[0056]
In each of the above embodiments, the impurity to be measured is nitrogen, but the quasi-thermal equilibrium state used in the present invention is a phenomenon that is established in the crystal by a thermodynamic phenomenon. Therefore, the present invention is not limited to nitrogen, and is applicable to the measurement of the concentration of carbon (C), which is an impurity that promotes the precipitation of oxygen, as in the case of nitrogen.
[0057]
In addition, as described above, the quasi-thermal equilibrium state used in the present invention is a phenomenon that is established in the crystal due to a thermodynamic phenomenon, and thus is a phenomenon that does not depend on the base material of the crystal, and is therefore limited to the silicon crystal. However, it is also applied to other group IV crystals such as SiGe crystals or Ge crystals, or other semiconductor crystals such as III-V group compound semiconductors such as GaAs, and a quasi-thermal equilibrium state is obtained in each crystal. It is only necessary to find the heat treatment conditions that can be obtained.
[0059]
【The invention's effect】
According to the present invention, since an infrared absorption difference spectrum after heat-treating a semiconductor crystal cut from the same semiconductor mother crystal such as a CZ-silicon wafer at different temperatures is used, a simple method of infrared absorption measurement is used. It is possible to quantify the concentration of added impurities in an impurity-added semiconductor crystal such as a nitrogen-added silicon wafer, which contributes greatly to improving the reliability of the semiconductor device.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a correlation between absorbance and heat treatment temperature at three infrared absorption peaks when a silicon crystal reaches a quasi-thermal equilibrium state.
FIG. 2 is an explanatory diagram of an infrared absorption difference spectrum at each heat treatment temperature.
FIG. 3 is a flowchart of a silicon crystal evaluation method according to the first embodiment of the present invention.
FIG. 4 is a flowchart of a silicon crystal evaluation method according to a second embodiment of the present invention.

Claims (12)

A first step of bringing the silicon crystal to a quasi-thermal equilibrium state at a first heating temperature;
A second step of measuring a first infrared absorption spectrum of the silicon crystal;
A third step of bringing the silicon crystal to a quasi-thermal equilibrium state at a second heating temperature;
A fourth step of measuring a second infrared absorption spectrum of the silicon crystal;
A fifth step of determining an infrared absorption difference spectrum between the first infrared absorption spectrum and the second infrared absorption spectrum, and determining an intensity of an absorption peak corresponding to a defect caused by nitrogen ;
A sixth step of determining a nitrogen concentration in the silicon crystal based on the intensity of the absorption peak;
The nitrogen concentration measuring method characterized by having. 963cm ^-1 as an absorption peak corresponding to the defects due to the nitrogen, 996cm ^-1, the nitrogen concentration measuring method according to claim 1, wherein the use of what appears to any one of wave numbers of 1018 cm ^-1. The nitrogen concentration measurement method according to claim 1 or 2 , wherein the sixth step calculates the nitrogen concentration based on the intensity of the absorption peak and a predetermined proportional conversion factor. Preparing a plurality of silicon crystals cut out from one silicon mother crystal;
The plurality of silicon crystal, the first silicon crystals at a first heating temperature, a first step occupying lead to quasi thermal equilibrium,
A second step of measuring a first infrared absorption spectrum of the first silicon crystal;
The plurality of silicon crystals, the second silicon crystals at a second heating temperature, and a third step of occupying lead to quasi thermal equilibrium,
A fourth step of measuring a second infrared absorption spectrum of the second silicon crystal;
A fifth step of determining an infrared absorption difference spectrum between the first infrared absorption spectrum and the second infrared absorption spectrum, and determining an intensity of an absorption peak corresponding to a defect caused by nitrogen ;
A sixth step of determining a nitrogen concentration in the silicon crystal based on the intensity of the absorption peak;
The nitrogen concentration measuring method characterized by having. The silicon mother crystal, nitrogen concentration measuring method according to claim 4 Symbol mounting, characterized in that a silicon wafer cut out from a silicon ingot pulled by the Czochralski method. As the absorption peak corresponding to the defects due to the nitrogen, 963cm ^-1, 996cm ^-1, the nitrogen concentration measurement according to claim 4 or 5, wherein the use of what appears to any one of wave numbers of 1018 cm ^-1 Method. 7. The nitrogen concentration according to claim 4, wherein the sixth step calculates the nitrogen concentration based on an intensity of the absorption peak and a predetermined proportional conversion factor. Measuring method. The silicon crystal whose nitrogen concentration has been measured in advance is brought to a quasi-thermal equilibrium state at the first heating temperature, and the first infrared absorption spectrum of the silicon crystal is measured,
The silicon crystal is brought to a quasi-thermal equilibrium state at a second heating temperature, and a second infrared absorption spectrum of the silicon crystal is measured,
Obtaining an infrared absorption difference spectrum between the first infrared absorption spectrum and the second infrared absorption spectrum, obtaining an intensity of an absorption peak corresponding to a defect caused by nitrogen ,
The method of calculating the strength and the previously measured nitrogen concentration and nitrogen concentration measurement proportional conversion factor, characterized in that calculated on the basis of the obtained absorption peak. As the absorption peak corresponding to the defects due to the nitrogen, 963cm ^-1, 996cm ^-1, proportion for nitrogen concentration measurement according to claim 8 Symbol mounting is characterized by using those appearing in any of the wave number of 1018 cm ^-1 Calculation method of conversion factor. The method for calculating a conversion factor for nitrogen concentration measurement according to claim 8 or 9, wherein the silicon crystal is obtained by measuring the nitrogen concentration in advance by secondary ion mass spectrometry or activation analysis. Heating the silicon crystal at different temperatures and reaching a quasi-thermal equilibrium at each temperature;
Measuring each infrared absorption spectrum of the silicon crystal after the heating;
Based on the difference of the infrared absorption spectrum, obtaining the intensity of the absorption peak corresponding to the defect caused by nitrogen ,
Obtaining a nitrogen concentration in the silicon crystal from the intensity of the absorption peak;
A method for measuring a nitrogen concentration in a silicon crystal, comprising: As the absorption peak corresponding to the defects due to the nitrogen, 963cm ^-1, 996cm ^-1, nitrogen in the silicon crystal according to claim 11, wherein the use of what appears to any one of wave numbers of 1018 cm ^-1 Concentration measurement method.

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