JP3465539B2 - Method and apparatus for evaluating oxygen concentration in semiconductor silicon crystal - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor crystal evaluation method, and more particularly to an evaluation method and apparatus suitable for evaluation of oxygen concentration in a semiconductor wafer. The present invention relates to a method and apparatus for evaluating oxygen concentration in a P-type or N-type semiconductor silicon crystal (a region that does not substantially permeate).

[0002]

2. Description of the Related Art Conventionally, a Fourier transform type infrared spectroscope (F
A light absorption method using (T-IR) is widely used. This method, by transmitting infrared light to the wafer,
It measures the amount of absorption by interstitial oxygen in a silicon crystal, and is based on the principle of quantifying the oxygen concentration in the crystal from the amount of absorption. This light absorption is very sensitive to the interstitial oxygen concentration in the silicon crystal, so
Highly reliable evaluation is possible.

However, the sample itself cannot be evaluated unless it transmits the infrared light used to a certain extent. For example, it is used as a substrate of an epitaxial wafer and has a low resistivity (for example, 20 mΩ · cm) that is highly doped. In the case of a silicon crystal of 10 mΩ · cm or less), light is absorbed by a large amount of free electrons contained in the sample,
Since it does not transmit light at all, the light absorption method cannot be applied to such crystals.

Conventionally, as a method for evaluating the oxygen concentration in a silicon crystal having a low resistivity as described above, a charged particle activation analysis method (CPAA method), a molten gas analysis method (GFA method), and a secondary ion mass spectrometry method have been used. (SIMS
Law), is known. Among them, the CPAA method is based on the principle of irradiating a sample with accelerated charged particles to activate oxygen in the crystal and then quantifying the amount of oxygen contained in the original sample from the amount of radiation emitted from the sample. It is a thing. However, it requires a cyclotron to generate accelerated charged particles, is not suitable for industrial in-line evaluation, such as radiation analysis, and is used only in special research institutions.

In the GFA method, a sample is melted at a high temperature to gasify oxygen contained in the sample as CO and CO ₂ , and the gas is chemically analyzed to contain oxygen contained in the original sample. It is based on the principle of quantifying the concentration. The GFA method has the advantages that the device is relatively inexpensive and that it does not require much skill for measurement and evaluation can be performed in a short time.
It is a complete destruction method because it requires melting of the sample.
That is, even if the sample once evaluated is re-evaluated for some reason, the sample is melted and cannot be evaluated. In addition, it is impossible to evaluate the product itself, and it is necessary to prepare samples other than the product that are used only for evaluation. This is a problem in quality assurance, and from a producer's point of view, it causes a great loss in terms of cost.

Further, due to the problem of sensitivity in chemical analysis of gas, a large sample of 2 mm to 10 mm square is generally required in order to increase the absolute amount of oxygen contained in the sample. However, even if a large sample is used, the reproducibility is not so good due to a problem in the apparatus such that the reaction efficiency to CO deteriorates. Furthermore, increasing the sample size means deteriorating the spatial resolution of the measurement, and even if one tries to examine the oxygen concentration distribution in the sample in detail, it is at most several meters.
There is also a drawback that it can be evaluated only on the order of m.

On the other hand, the SIMS method is to irradiate the surface of a sample with an ion beam under a high vacuum and to measure secondary ions sputtered from the sample by using a mass spectrometer. Since SIMS method is a mass spectrometry method, any element can be analyzed by selecting the ions to be irradiated, and it has the advantages of high detection sensitivity and high spatial resolution due to the narrow measurement area, but it requires expensive equipment. In addition, the conditions such as the degree of vacuum of the apparatus must be kept good, and it takes time to measure one sample.
Further, this method is also a destructive method and has the same drawback as the GFA method in that a sample for inspection is required separately from the product.

[0008]

The present invention has been made to solve the drawbacks of the conventional method, and has a low resistivity (for example, 20 mΩ · cm or less, particularly 10 mΩ · cm).
It is an object of the present invention to provide a method and a device for evaluating the oxygen concentration in a semiconductor silicon crystal having a size of 1 cm or less) with high sensitivity and good reproducibility at a nondestructive and low cost.

[0009]

It has been conventionally known that absorption of infrared light near the wave number of 1107 cm ^-1 by interstitial oxygen in a semiconductor silicon crystal is observed by a transmission method or a reflection method. However, this has a resistivity of several Ω · cm.
Among the above crystals, it was observed only for semiconductor crystals that are less affected by the absorption of infrared light by free electrons. That is, in the case of a low resistivity (for example, several mΩ · cm to several tens of mΩ · cm) semiconductor silicon crystal to which a dopant (for example, boron or antimony) is added at a high concentration, which is particularly targeted in the present invention, the above interstitial lattice is used in the transmission method. The spectrum of light absorption by oxygen cannot be observed.

Therefore, the inventors of the present invention thought that information on the oxygen concentration in the crystal would appear in other physical constants other than the absorption spectrum, and as a result of earnest research on this, the dielectric function in the infrared region and the oxygen in the crystal were investigated. For the first time, it was found that there was a correlation between the concentrations, and the present invention was completed.

That is, the invention described in claim 1 of the present invention for solving the above-mentioned problems is to irradiate a semiconductor silicon crystal with light having an arbitrary wave number of 2000 cm ^-1 or less, and to irradiate the reflected light thereof. An oxygen concentration evaluation method characterized in that the real part of the dielectric function at the arbitrary wave number is obtained from the amplitude ratio ψ and the phase difference Δ with respect to light, and the oxygen concentration contained in the semiconductor silicon crystal is evaluated from this value. .

By performing evaluation using such a method, for example, even when the semiconductor silicon crystal to be evaluated has a low resistivity and cannot be evaluated by the transmission method, non-destructive and low cost which cannot be achieved by the conventional method can be obtained. Thus, it became possible to evaluate the oxygen concentration in the semiconductor crystal with high sensitivity and good reproducibility.

The invention described in claim 2 of the present invention is the method for evaluating oxygen concentration according to claim 1, wherein a plurality of semiconductor silicon crystals having different known oxygen concentrations are used.
By irradiating light including an arbitrary wave number of cm ⁻¹ or less, and obtaining the real part of the dielectric function of the arbitrary wave number at each oxygen concentration from the amplitude ratio ψ and the phase difference Δ of the reflected light with respect to the irradiation light, This is an oxygen concentration evaluation method characterized in that the correlation between the oxygen concentration at the wave number and the real part of the dielectric function is obtained.

In this way, the oxygen concentration can be determined by previously creating a correlation (calibration curve or correlation equation) between the real part of the dielectric function at an arbitrary wave number of reflected light in the infrared region and the oxygen concentration in the semiconductor crystal. It is possible to measure a specific oxygen concentration for an unknown semiconductor silicon crystal. That is, the oxygen concentration is unknown to the semiconductor silicon crystal, the light containing the wave number previously obtained correlation is radiated to determine the real part of the dielectric function at that wave number, and by applying the value of this real part of the dielectric function to the above correlation, The oxygen concentration of the sample can be measured.

The invention described in claim 3 of the present invention is the oxygen concentration evaluation method according to claim 1 or 2, wherein the resistivity of the semiconductor silicon crystal to be evaluated is 1 or less.
It is characterized by being Ω · cm or less.

In the semiconductor silicon crystal having a resistivity of 1 Ω · cm or less, infrared light hardly passes through the sample. Therefore, in the conventional transmission method, the spectrum of infrared light absorption by interstitial oxygen is used. Can not be observed,
It is impossible to evaluate the oxygen concentration. Therefore,
The present invention is particularly effective when used for evaluating the oxygen concentration of semiconductor silicon crystals in this range.

The invention according to claim 4 of the present invention is the oxygen concentration evaluation method according to any one of claims 1 to 3, wherein an arbitrary wave number used for the oxygen concentration evaluation is , 1000 cm ⁻¹ or less.

As described above, when the arbitrary wave number used for the oxygen concentration evaluation is set to 1000 cm ^-1 or less, the change in the real part of the dielectric function at the wave number is large with respect to the change in the oxygen concentration. Can be evaluated.

The invention described in claim 5 of the present invention is the oxygen concentration evaluation method according to any one of claims 1 to 4, wherein the reflected light of the reflected light is measured using an infrared spectroscopic ellipsometer. The amplitude ratio ψ and the phase difference Δ with respect to the irradiation light are measured, and the real part of the dielectric function at the arbitrary wave number is obtained.

As described above, in the method of the present invention, non-contact and non-destructive measurement can be performed by performing the dielectric function in the infrared light region using such an infrared spectroscopic ellipsometer. Then, since it is a non-contact, non-destructive measurement, if the relationship between the dielectric function of an arbitrary wave number in the infrared light region and the oxygen concentration in the semiconductor crystal is investigated in advance and a calibration curve or a correlation equation is created, This can be used to evaluate the product wafer itself. In addition, repeated measurement and in-plane distribution measurement can be performed, and the crystal quality can be accurately confirmed.

The invention according to claim 6 of the present invention is the oxygen concentration evaluation method according to any one of claims 1 to 5, wherein the surface of the semiconductor silicon crystal is subjected to mechanochemical polishing or chemical etching. It is characterized in that it is evaluated after the treatment.

Thus, by subjecting the sample surface to mechanochemical polishing or chemical etching, the influence of the surface condition such as diffuse reflection can be removed, and the measurement accuracy can be improved.

According to a seventh aspect of the present invention, a semiconductor silicon crystal is irradiated with light including an arbitrary wave number of 2000 cm ^-1 or less, and the reflected light from the semiconductor silicon crystal is detected. The measuring means includes an measuring means for measuring the amplitude ratio ψ and the phase difference Δ from the detected reflected light, and an evaluating means for evaluating the oxygen concentration contained in the semiconductor from the measured amplitude ratio ψ and the phase difference Δ. It is an oxygen concentration evaluation apparatus for semiconductor silicon crystals.

With such an apparatus, it becomes possible to carry out the method according to any one of claims 1 to 6,
For example, even if the semiconductor silicon crystal to be evaluated has a low resistivity and cannot be evaluated by the transmission method, it is possible to evaluate the oxygen concentration in the semiconductor crystal with high sensitivity and good reproducibility at a nondestructive and low cost that could not be achieved by the conventional method. It is possible to do.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The oxygen concentration evaluation method of the present invention will be described below in detail with reference to the drawings showing an example of the embodiment. FIG. 1 is a schematic view showing an infrared spectroscopic ellipsometer as an example of an apparatus for measuring a dielectric function in an infrared light region according to the present invention.

In this apparatus, it is preferable that the semiconductor silicon crystal 1 as the sample to be evaluated and the measuring apparatus main body 2 are controlled and arranged at a constant temperature near room temperature. This is to remove the influence of environmental temperature and improve the measurement accuracy.

In this example, first, light (irradiation light) 3 containing an arbitrary wave number of 2000 ⁻¹ cm or less is applied to the semiconductor silicon crystal 1 as a sample. The irradiation light 3 irradiates the semiconductor silicon crystal 1 with the light emitted from the light source 11 being polarized by the polarizer 4 and having its polarization axis rotated by the photoelastic modulator 5.

The semiconductor silicon crystal 1 having a relatively low resistivity doped with a high concentration is more suitable for the oxygen concentration evaluation method of the present invention. Specifically, the resistivity is 1 Ω · cm or less, particularly 0.1 Ω · c
It has a resistivity of m or less. This is because such a low-resistivity semiconductor silicon crystal cannot be measured by a conventional transmission method, and the method of the present invention is highly superior.

The semiconductor silicon crystal 1 used for the measurement
Is preferably one whose surface has been subjected to mechanochemical polishing or chemical etching. This is because the effect of the surface condition such as light scattering on the surface can be removed by performing such a treatment. Furthermore, when a plurality of samples are evaluated, it is preferable that the surface treatment of each sample be constant.

In the present invention, it is considered that the natural oxide film existing on the sample surface has almost no influence. This is because the film thickness of the natural oxide film is negligibly smaller than the light penetration depth. Therefore, it is not always necessary to remove this oxide film by hydrofluoric acid cleaning or the like before the measurement, but if it is removed, more accurate measurement can be performed.

The illumination light 3 is not particularly limited as long as light having any wave number below 2000 ^{over 1} cm, for example, may be used white light, also arbitrary wavenumber 10
If a 00cm ^-1 may be irradiated with 1000 cm ^-1 following infrared light.

In this example, next, the irradiation light 3 applied to the semiconductor silicon crystal 1 is detected by the detector 9 as reflected light 6 through the analyzer 7 and the monochromator 8.
The optical constants directly detected by this infrared spectroscopic ellipsometer are the phase difference Δ and the amplitude reflectance ratio (amplitude ratio) ψ. The dielectric function is obtained by analyzing these values using the personal computer 10.

Generally, when the light is reflected on the surface of the sample, the polarization state is different from that of the irradiation light. However, the polarization state of the reflected light is monitored by a rotary analyzer and compared with the irradiation light to obtain a phase difference Δ and an amplitude. The reflectance ratio (amplitude ratio) ψ is calculated.
In the case of bulk, the refractive index n and the extinction coefficient k (or the real part ε1 and the imaginary part ε2 of the dielectric constant) are calculated exactly from Δ and ψ. For example, the dielectric function used in the present invention is obtained by the following equations (1) to (3) when the thickness of the medium is infinite (when there is no reflection on the back surface). ε (complex dielectric constant) = [n × (complex refractive index)] ² (1) ε (complex dielectric constant) = ε1 + iε2 (2) n × (complex refractive index) = n + ik ( 3)

The dielectric function (also called complex permittivity) used in the present invention has a real part (real part) ε1 of this dielectric constant,
The imaginary part (imaginary number part) ε2 is shown. Thus, the dielectric function has a real part and an imaginary part, both of which are correlated with the oxygen concentration. Therefore, either of them can be used, but since the imaginary part tends to be highly dependent on the resistivity, it is preferable to use the real part.

[0035] As also in this embodiment, in the present invention, in any wavenumbers below 2000 ^{over 1} cm, obtains a phase difference Δ and the amplitude ratio ψ with respect to the irradiation light of the reflected light as described above, the dielectric from these The oxygen concentration of the semiconductor silicon crystal is evaluated by obtaining the function real part. Here, evaluation of oxygen concentration is a concept including, for example, relative oxygen concentration evaluation of a plurality of semiconductor silicon crystals, specific oxygen concentration measurement of semiconductor silicon crystals, and the like.

In the present invention, in order to measure the specific oxygen concentration of the semiconductor silicon crystal, it is not enough to simply obtain the real part of the dielectric function. It needs to be decided based on the correlation. Such a correlation is obtained by irradiating a plurality of semiconductor silicon crystals having different known oxygen concentrations with light including an arbitrary wave number of 2000 cm ⁻¹ or less, and from the amplitude ratio ψ and the phase difference Δ of the reflected light to the irradiation light. It can be obtained by obtaining the real part of the dielectric function of the arbitrary wave number at each oxygen concentration.

The term "plurality" as used herein means a number at which the correlation between the real part of the dielectric function and the oxygen concentration at an arbitrary wave number can be obtained, and is usually about 3 to 7 levels. As the semiconductor silicon crystal used, one having a known oxygen concentration whose oxygen concentration has been measured in advance by the GFA method or the like is used. Further, taking the correlation here means, for example, preparation of a calibration curve, determination of a correlation equation, etc., although not limited thereto.

Usually, a sample containing several levels of known oxygen concentration is measured, and a spectrum in the infrared region of the real part of the dielectric function is measured. Next, the correlation between the oxygen concentration and the real part of the dielectric function is obtained at any wave number in this spectrum.

Here, in order to accurately measure the oxygen concentration, it is desirable to obtain a correlation for each resistivity (for example, create a calibration curve). This is because the resistivity affects the penetration depth of the irradiation light (in semiconductor crystals having a resistivity of several Ω · cm or more, the penetration depth of the irradiation light is large, and depending on the thickness of the sample, It may also be affected), that is, the difference in the penetration depth due to the difference in the resistivity and the strength of the dielectric function are different. Therefore, the resistivity is different from the real part of the dielectric function and the oxygen concentration. This is because it affects the correlation of.

Therefore, in order to obtain the oxygen concentration more accurately, the resistivity is finely divided, and the correlation between the dielectric function and the oxygen concentration is obtained in advance for each resistivity, and the correlation close to the resistivity of the sample to be measured is obtained. It is preferable to use and measure the oxygen concentration. Also check the correlation between the oxygen concentration and the dielectric function of 5 Ω · cm or more where infrared light easily penetrates into the sample, and the correlation between the dielectric function of 1 Ω · cm or less and the oxygen concentration that infrared light does not penetrate. Etc. are also important.

The arbitrary wave number used in the present invention is a wave number for which the real part of the dielectric function at that wave number is obtained and the oxygen concentration is evaluated, and is appropriately selected within the range of 2000 cm ^-1 or less. . It is not particularly limited as long as it is 2000 cm ^-1 or less, but the range in which this arbitrary wave number is selected is preferably 1000 cm ^-1 or less. This is because the change in the real part of the dielectric function at the wave number is large with respect to the change in the oxygen concentration, as will be understood from the examples described later, so that the oxygen concentration can be evaluated more accurately. In this case, 2000 cm ^-1
If the number of waves exceeds, the difference in the dielectric function with respect to the change in oxygen concentration does not appear, and therefore it cannot be evaluated.

Next, the oxygen concentration evaluation apparatus of the present invention will be described. The device of the present invention is suitable for semiconductor silicon crystals.
Irradiating means for irradiating light including an arbitrary wave number of 000 cm ⁻¹ or less, and measuring means for detecting reflected light from the semiconductor silicon crystal and measuring the amplitude ratio ψ and the phase difference Δ from the detected reflected light. An evaluation device for evaluating the oxygen concentration of a semiconductor silicon crystal, comprising: an evaluation means for evaluating the oxygen concentration contained in the semiconductor from the measured amplitude ratio ψ and phase difference Δ.

The irradiation means used in the present invention is 2000
Any light source can be used as long as it can irradiate light having an arbitrary wave number of cm ⁻¹ or less. An infrared spectroscopic ellipsometer may be used as the measuring means, but the measuring means is not limited to this, as described above. As the evaluation means, a commonly used personal computer can be mentioned.

For example, in FIG. 1, the irradiation means is the light source 11, the polarizer 4 and the photoelastic modulator 5, and the measuring means is the analyzer 7 and the monochromator 8.
And the detector 9 corresponds. The evaluation means is the personal computer 10. In addition, the description of the same items as the above-described oxygen concentration evaluation method such as semiconductor silicon crystal and arbitrary wave number is the same as the evaluation method, and therefore the description is omitted here.

[0045]

EXAMPLES Next, examples of the present invention will be shown below, but the present invention is not limited thereto. (Embodiment) First, an apparatus having a structure as shown in FIG. 1, for example, in this embodiment, IRL or SE manufactured by JOBIN YVON.
Using the N950 SE950-FIR infrared spectroscopic ellipsometer, the oxygen concentration was 11.0, 13.0, 15.0, 17.0, 19.0ppma.
(JEIDA scale; hereinafter, this unit is used for all oxygen concentration units), and the boron concentration is about 5 × 10.
Silicon atoms of ¹⁸ atoms / cm ³ (resistivity of about 0.01 to 0.02 Ω · cm) manufactured by the Czochralski method and boron of about 5 × 10 ¹⁸ atoms / cm ³ manufactured by the epitaxial growth method containing almost no oxygen. The spectrum of the dielectric function (real part) in the containing silicon crystal was measured in the infrared region. The result is shown in FIG.

Looking at this dielectric function spectrum, the intensity of the real part of the dielectric function becomes lower over the entire infrared light wave number region as the oxygen concentration becomes lower, and between the oxygen concentration and the real part of the dielectric function. It can be seen that there is an extremely strong correlation.

For example, looking at the real part of the dielectric function at a wave number of 1000 ^-1 cm, the more oxygen is contained, the stronger the real part of the dielectric function is. Therefore, it is possible to evaluate the oxygen concentration based on this difference in intensity. Specifically, FIG. 3 shows the real part of the dielectric function at this wave number on the vertical axis and the oxygen concentration on the horizontal axis. The oxygen concentration is an average value of 5 samples prepared from the same crystal and measured by the conventional GFA method.

In this embodiment, 1000 is set as an arbitrary wave number.
By selecting cm ⁻¹ and confirming the correlation between the real part of the dielectric function and the oxygen concentration at this wave number, any wave number in the wave number region shown in FIG. 2 (for example, 800 cm ⁻¹ , 900 cm
It is clear that the correlation can be confirmed even if ( ^-1 etc.) is selected as an arbitrary wave number, and the difference in oxygen concentration with respect to the difference in intensity of the real part of the dielectric function is clearer on the low wave number side.

By creating a correlation diagram (calibration curve) between the real part of the dielectric function and the oxygen concentration by such a method, the oxygen concentration in any sample can be measured thereafter in a non-contact and non-destructive manner. That is, if the low resistance semiconductor silicon single crystal to be measured is irradiated with light having an arbitrary wave number and the real part of the dielectric function is obtained, the oxygen concentration can be obtained from the calibration curve.

Therefore, three silicon wafers with an unknown oxygen concentration (resistivity 0.015 Ω · cm) were irradiated with light containing a wave number of 1000 cm ⁻¹ to evaluate the oxygen concentration. The real parts of the dielectric function at 1000 cm ⁻¹ of these materials were 10.7, 10.8 and 10.9, respectively. Therefore, from FIG. 3, the oxygen concentration is 11.0 ppma,
It could be quantified to 15.5 ppma and 19.0 ppma.

Before the present invention was completed, there was no example of taking a dielectric function spectrum in the infrared region in a semiconductor silicon crystal doped with boron or the like at a high concentration, let alone a real part of the dielectric function. It was unknown at all that there was a correlation between oxygen concentration and oxygen concentration. The present invention is characterized in that it was confirmed for the first time that the oxygen concentration was obtained using this dielectric function in the infrared region.

The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the scope of claims of the present invention It is included in the technical scope of.

For example, in the above embodiment, the infrared spectroscopic ellipsometer was mentioned as an example of the device for measuring the dielectric function. However, as can be understood from the principle, any device that can accurately measure the dielectric function in the infrared region can be used. It is not limited.

[0054]

The present invention provides a semiconductor silicon crystal having
A light including an arbitrary wave number of 00 cm ^-1 or less is irradiated, and the real part of the dielectric function at the arbitrary wave number is obtained from the amplitude ratio ψ and the phase difference Δ of the reflected light with respect to the irradiation light, and from this value, the semiconductor silicon crystal is obtained. Since it is characterized by performing the evaluation of the oxygen concentration contained in the semiconductor silicon crystal to be evaluated has a low resistivity and cannot be evaluated by the transmission method, the non-destructive method cannot be performed by the conventional method. Moreover, it has become possible to evaluate the oxygen concentration in a semiconductor crystal with high sensitivity and good reproducibility at low cost.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing one embodiment of an apparatus for carrying out the method of the present invention.

FIG. 2 is a graph showing a spectrum of a real part of a dielectric function in an infrared light wavelength region according to the present invention.

FIG. 3 is a graph showing a correlation between a real part of a dielectric function at a wave number of 1000 cm ⁻¹ and a known oxygen concentration measured by the GFA method according to the present invention.

[Explanation of symbols]

1 ... Semiconductor silicon crystal, 2 ... Measuring device main body, 3 ... Irradiation light, 4 ... Polarizer,
5 ... Photoelastic modulator, 6 ... Reflected light, 7 ... Analyzer, 8 ... Monochromator, 9 ... Detector, 10 ... Personal computer, 11 ... Light source.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-341952 (JP, A) JP-A-62-251636 (JP, A) JP-A-63-52004 (JP, A) JP-A-3- 119745 (JP, A) JP-A-54-140869 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 21/00-21/61 JISC file (JOIS) Practical file (PATOLIS) ) Patent file (PATOLIS)

Claims (7)

(57) [Claims] 1. A semiconductor silicon crystal having a density of 2000 cm ^-1
Irradiate light including any of the following wave numbers, and obtain the real part of the dielectric function at the arbitrary wave number from the amplitude ratio ψ and the phase difference Δ of the reflected light with respect to the irradiation light, and include it in the semiconductor silicon crystal from this value. The method for evaluating the oxygen concentration of a semiconductor silicon crystal is characterized in that the oxygen concentration is evaluated. 2. A plurality of semiconductor silicon crystals having different known oxygen concentrations are irradiated with light including an arbitrary wave number of 2000 cm ⁻¹ or less, and an amplitude ratio ψ of the reflected light to the irradiated light.
The correlation between the oxygen concentration and the real part of the dielectric function at the wave number is obtained in advance by obtaining the real part of the dielectric function of the arbitrary wave number at each oxygen concentration from the phase difference Δ and the phase difference Δ. Oxygen concentration evaluation method. 3. The semiconductor silicon crystal has a resistivity of 1
3. The oxygen concentration evaluation method according to claim 1, wherein the oxygen concentration is Ω · cm or less. 4. The oxygen concentration evaluation method according to claim 1, wherein the arbitrary wave number is 1000 cm ⁻¹ or less. 5. An infrared spectroscopic ellipsometer is used to measure an amplitude ratio ψ and a phase difference Δ of the reflected light with respect to the irradiation light to obtain a real part of a dielectric function at the arbitrary wave number. The oxygen concentration evaluation method according to any one of claims 1 to 4. 6. The oxygen concentration evaluation method according to claim 1, wherein the evaluation is performed after the surface of the semiconductor silicon crystal is subjected to a mechanochemical polishing or a chemical etching treatment. 7. A semiconductor silicon crystal having a density of 2000 cm ^-1
Irradiating means for irradiating light including any of the following wave numbers, measuring means for detecting reflected light from the semiconductor silicon crystal, and measuring means for measuring the amplitude ratio ψ and the phase difference Δ from the detected reflected light, And an evaluation means for evaluating the oxygen concentration contained in the semiconductor from the amplitude ratio ψ and the phase difference Δ.