JPH1114543A - Method and system for evaluating concentration of oxygen in semiconductor silicon crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evaluate the concentration of oxygen in a semiconductor silicon crystal by irradiating the crystal with a light containing an arbitrary wave number within a specified range and then determining the real part of a dielectric function from the amplitude ratio and the phase difference between the reflected light and the irradiating light. SOLUTION: An irradiating light 3 from a light source 11 containing an arbitrary wave number of 2000<-1> cm or less is polarized through a polarizer 4 and directed toward a semiconductor silicon crystal 1 by turning the polarization axis through a photoelastic modulator 5. The reflected light 6 is passed through an analyzer 7 and a monochromator 8 and detected by a detector 9. The phase difference and the amplitude ratio are then detected directly by means of an infrared spectroellipsometer and inputted to a personal computer 10 where they are analyzed to determine a dielectric function. The reflected light 6 is polarized differently from the irradiating light 3 and the rotary analyzer 7 compares the polarized state with that of the irradiating light 3 before the phase difference and the amplitude ratio are calculated. The dielectric function has the real and imaginary parts of permittivity and the oxygen concentration of the semiconductor silicon crystal 1 is evaluated based on the real part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as a method for evaluating the oxygen concentration in a semiconductor silicon crystal, a Fourier transform type infrared spectrometer (F
A light absorption method using T-IR) is widely used. This method transmits infrared light to the wafer,
It measures the amount of absorption by interstitial oxygen in the 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.
High reliability evaluation is possible.

However, if the sample does not transmit the infrared light used to some extent, the evaluation itself is impossible. For example, a highly doped low resistivity (for example, 20 mΩ · cm) used as a substrate of an epitaxial wafer. 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 no light is transmitted at all, the light absorption method cannot be applied to such a crystal at all.

Conventionally, the above-mentioned methods for evaluating the oxygen concentration in a silicon crystal having a low resistivity include charged particle activation analysis (CPAA), melting gas analysis (GFA), and secondary ion mass spectrometry. (SIMS
Law), is known. The CPAA method is based on the principle that the sample is irradiated with accelerated charged particles to activate oxygen in the crystal, and then the amount of oxygen contained in the original sample is determined from the amount of radiation emitted from the sample. Things. However, a cyclotron for generating accelerated charged particles is required, and it is not suitable for industrial inline evaluation such as radiation analysis, and is used only by special research institutions.

The GFA method melts a sample at a high temperature to gasify oxygen contained in the sample as CO or CO ₂ , and chemically analyzes the gas to analyze the oxygen contained in the original sample. It is based on the principle of quantifying the concentration. The GFA method has an advantage that the apparatus is relatively inexpensive and the evaluation can be performed in a short time without requiring much skill in the measurement.
It is a complete destruction method because the sample must be melted.
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 a sample used only for the evaluation must be prepared other than the product. This is a problem in terms of quality assurance, and from the producer's point of view, is a great loss in terms of cost.

Also, due to the problem of sensitivity in the chemical analysis of gas, a large sample of generally 2 mm to 10 mm square is required to increase the absolute amount of oxygen contained in the sample. However, even if a large sample is used, the reproducibility is not very good due to equipment problems such as a decrease in the reaction efficiency to CO. Furthermore, enlarging the sample size means deteriorating the spatial resolution of the measurement, and even when trying to examine the oxygen concentration distribution in the sample in detail, at most several m
There is also a disadvantage that evaluation can be performed only on the order of m.

On the other hand, in the SIMS method, an ion beam is irradiated to a sample surface under a high vacuum, and secondary ions generated by sputtering from the sample are measured using a mass spectrometer. Since SIMS is a mass spectrometry, 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 small measurement area, but requires expensive equipment. In addition, there is a disadvantage that the condition such as the degree of vacuum of the apparatus must be kept good, and it takes time to measure one sample.
This method is also a destructive method, and has the same drawback as the GFA method in that a test sample is required separately from a product.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve such disadvantages of the conventional method, and has a low resistivity (for example, 20 mΩ · cm or less, particularly 10 mΩ · cm).
cm or less) is provided.

[0009]

Heretofore, it has been known that the absorption of infrared light having a wavenumber of about 1107 cm ^-1 by interstitial oxygen in a semiconductor silicon crystal is observed by both the transmission method and the reflection method. However, this has a resistivity of several ohm-cm
Among the above crystals, only those semiconductor crystals which are less affected by infrared light absorption by free electrons are observed. That is, in the case of a semiconductor silicon crystal having a low resistivity (for example, several mΩ · cm to several tens of mΩ · cm) 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-mentioned interstitial is used in the transmission method The spectrum of light absorption by oxygen cannot be observed.

Therefore, the present inventors considered whether information on the oxygen concentration in the crystal may appear in other physical constants other than the absorption spectrum, and as a result of intensive research, the dielectric function in the infrared light region and the oxygen in the crystal were examined. It has been found for the first time that there is a correlation between the concentrations, and the present invention has been completed.

That is, according to the first aspect of the present invention for solving the above-mentioned problem, the semiconductor silicon crystal is irradiated with light having an arbitrary wave number of 2000 cm ^-1 or less, and the reflected light is irradiated on the semiconductor silicon crystal. An oxygen concentration evaluation method comprising: obtaining a real part of a dielectric function at the arbitrary wave number from an amplitude ratio ψ to light and a phase difference Δ; and evaluating an oxygen concentration contained in the semiconductor silicon crystal from the value. .

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

According to a second aspect of the present invention, there is provided the method for evaluating an oxygen concentration according to the first aspect, wherein a plurality of semiconductor silicon crystals having known and different oxygen concentrations are provided with 2000 times.
irradiating light containing an arbitrary wave number of cm ^-1 or less, and obtaining the dielectric function real part of the arbitrary wave number at each oxygen concentration from the amplitude ratio ψ and the phase difference Δ of the reflected light to the irradiation light, This is an oxygen concentration evaluation method characterized by determining a correlation between the oxygen concentration at the wave number and the real part of the dielectric function.

As described above, the correlation (calibration curve or correlation equation) between the real part of the dielectric function at an arbitrary wave number of the reflected light in the infrared region and the oxygen concentration in the semiconductor crystal is made in advance, so that the oxygen concentration can be reduced. It is possible to measure a specific oxygen concentration of an unknown semiconductor silicon crystal. In other words, by irradiating a semiconductor silicon crystal whose oxygen concentration is unknown to light containing a wave number obtained in advance to obtain the real part of the dielectric function at the wave number, and applying the value of the real part of the dielectric function to the correlation, The oxygen concentration of the sample can be measured.

According to a third aspect of the present invention, there is provided the oxygen concentration evaluation method according to the first or second aspect, wherein the semiconductor silicon crystal to be evaluated has a resistivity of 1%.
Ω · cm or less.

In such a semiconductor silicon crystal having a resistivity of 1 Ω · cm or less, since infrared light hardly passes through the sample, the absorption spectrum of infrared light by interstitial oxygen is determined by the conventional transmission method. Cannot be observed,
It is not possible 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.

According to a fourth aspect of the present invention, there is provided the oxygen concentration evaluation method according to any one of the first to third aspects, wherein an arbitrary wave number used for the oxygen concentration evaluation is determined. , 1000 cm ⁻¹ or less.

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

According to a fifth aspect of the present invention, there is provided the oxygen concentration evaluation method according to any one of the first to fourth aspects, wherein the reflected light is measured using an infrared spectroscopic ellipsometer. The amplitude ratio に 対 す る 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, according to the method of the present invention, the non-contact / 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 and 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 examined in advance, and a calibration curve or a correlation equation is created, Using this, it is possible to evaluate the product wafer itself. In addition, repeated measurement and in-plane distribution measurement can be performed, and crystal quality can be accurately confirmed.

According to a sixth aspect of the present invention, there is provided the method for evaluating oxygen concentration according to any one of the first to fifth aspects, wherein the surface of the semiconductor silicon crystal is subjected to mechanochemical polishing or chemical etching. It is characterized in that evaluation is performed after processing is performed.

As described above, by subjecting the sample surface to mechanochemical polishing or chemical etching, the influence of the surface state such as irregular reflection can be eliminated, and the measurement accuracy can be improved.

According to a seventh aspect of the present invention, there is provided an irradiation means for irradiating a semiconductor silicon crystal with light having an arbitrary wave number of 2000 cm ^-1 or less, and detecting reflected light from the semiconductor silicon crystal; Measuring means for measuring the amplitude ratio 位相 and phase difference Δ from the detected reflected light, and evaluation means for evaluating the concentration of oxygen contained in the semiconductor from the measured amplitude ratio ψ and phase difference Δ This is an apparatus for evaluating oxygen concentration of semiconductor silicon crystals.

With such an apparatus, it is possible to carry out the method according to 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, evaluation of the oxygen concentration in the semiconductor crystal with high sensitivity and reproducibility, which is not possible with the conventional method, is nondestructive, low cost, and is not possible. Can be performed.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an oxygen concentration evaluation method according to the present invention will be described in detail with reference to the drawings showing an embodiment. FIG. 1 is a schematic diagram 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, the semiconductor silicon crystal 1 to be evaluated and the measuring apparatus main body 2 are preferably arranged so as to be controlled at a constant temperature near room temperature. This is to remove the influence of the environmental temperature and increase the measurement accuracy.

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

It is preferable that the semiconductor silicon crystal 1 has a relatively low resistivity doped with a high concentration as a target of the oxygen concentration evaluation method of the present invention. Specifically, the resistivity is 1 Ω · cm or less, particularly 0.1 Ω · c
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 advantageous.

The semiconductor silicon crystal 1 used for measurement
Is preferably one whose surface has been subjected to mechanochemical polishing or chemical etching treatment. By performing such a treatment, the influence of the surface state such as light scattering on the surface can be removed. Further, when evaluating a plurality of samples, it is preferable to keep the surface treatment of each sample 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 thickness of the natural oxide film is so small as to be negligible compared to the penetration depth of light. Therefore, it is not always necessary to remove the oxide film by hydrofluoric acid cleaning or the like before 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 as reflected light 6 by the detector 9 through the analyzer 7 and the monochromator 8.
Optical constants directly detected by the infrared spectroscopic ellipsometer are a phase difference Δ and an amplitude reflectance ratio (amplitude ratio) ψ. The dielectric function is obtained by analyzing these values using the personal computer 10.

In general, when light is reflected on the sample surface, the polarization state is different from that of the irradiation light. The polarization state of the reflected light is monitored by a rotating analyzer and compared with the irradiation light to obtain the phase difference Δ and the amplitude. Calculate the reflectance ratio (amplitude ratio) ψ.
In the case of a 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 strictly calculated 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 permittivity) = [n × (complex refractive index)] ² (1) ε (complex permittivity) = ε1 + iε2 (2) nx (complex refractive index) = n + ik (2) 3)

The dielectric function (also called complex permittivity) used in the present invention is the real part (real part) ε1,
The imaginary part (imaginary 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, any of them can be used, but since the imaginary part tends to be highly dependent on 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 real part of the function. Here, the evaluation of the oxygen concentration is a concept including, for example, the evaluation of the relative oxygen concentration of a plurality of semiconductor silicon crystals, the measurement of the specific oxygen concentration of the semiconductor silicon crystal, and the like.

In the present invention, in order to measure the specific oxygen concentration of the semiconductor silicon crystal, it is not sufficient to simply determine the real part of the dielectric function, and the correlation between the real part of the dielectric function and the oxygen concentration is determined in advance. It must be determined based on the correlation. Such a correlation is obtained by irradiating a plurality of semiconductor silicon crystals having different known oxygen concentrations with light having an arbitrary wave number of 2000 cm ^-1 or less, and calculating an amplitude ratio ψ and a phase difference Δ of the reflected light with respect 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.

Here, the term "plurality" is such a number that a 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. Further, as the semiconductor silicon crystal to be used, one having a known oxygen concentration whose oxygen concentration is measured in advance by the GFA method or the like is used. The term “correlation” used herein means, but is not limited to, for example, creation of a calibration curve, determination of a correlation equation, and the like.

Usually, a sample containing several levels of known oxygen concentration is measured, and the 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 an arbitrary 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, to prepare a calibration curve). This is because the resistivity affects the penetration depth of the irradiation light (in a semiconductor crystal 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 depends on the thickness of the sample. May be affected), that is, the difference in the penetration depth is caused by the difference in the resistivity, and the strength of the dielectric function is different. For example, the resistivity is different from the real part of the dielectric function and the oxygen concentration. Is to affect the correlation.

Therefore, when it is desired to obtain the oxygen concentration more accurately, the resistivity is finely divided, and the correlation between the dielectric function and the oxygen concentration is determined in advance for each resistivity, and the correlation close to the resistivity of the sample to be measured is obtained. It is preferable to measure the oxygen concentration. In addition, confirm the correlation between the dielectric function of 5 Ω · cm or more and the oxygen concentration, at which infrared light easily penetrates into the sample, and the correlation between the dielectric function of 1 Ω · cm or less, at which infrared light does not penetrate, and the oxygen concentration. Etc. are also important.

The arbitrary wave number used in the present invention is a wave number at which the real part of the dielectric function at the wave number is obtained and the oxygen concentration is evaluated, and is appropriately selected in the range of 2000 cm ^-1 or less. . There is no particular limitation as long as it is 2000 cm ^-1 or less, but the range where 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, so that the oxygen concentration can be more accurately evaluated, as will be understood from the examples described later. In this case, 2000 cm ^-1
If the wave number is more than, the difference in the dielectric function with respect to the change in the oxygen concentration does not appear, so that the evaluation cannot be performed.

Next, the oxygen concentration evaluation apparatus of the present invention will be described. The device of the present invention is capable of adding 2
Irradiating means for irradiating light containing an arbitrary wave number of 000 cm ^-1 or less, and measuring means for detecting reflected light from the semiconductor silicon crystal and measuring an amplitude ratio ψ and a phase difference Δ from the detected reflected light. And an evaluation means for evaluating the concentration of oxygen 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 emit light having an arbitrary wave number of cm ^-1 or less. In addition, examples of the measuring unit include an infrared spectroscopic ellipsometer, but are not limited thereto as described above. Examples of the evaluation means include a personal computer that is usually used.

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

[0045]

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

Looking at the dielectric function spectrum, the intensity of the real part of the dielectric function is lower as the oxygen concentration is lower over the entire infrared light wave number region, and the difference between the oxygen concentration and the intensity of the real part of the dielectric function is smaller. Has a very strong correlation.

For example, looking at the real part of the dielectric function at a wave number of 1000 ^-1 cm, the strength of the real part of the dielectric function increases as the oxygen content increases. Therefore, it is possible to evaluate the oxygen concentration based on the difference in the 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 five samples prepared from the same crystal and measured by the conventional GFA method.

In this embodiment, an arbitrary wave number of 1000
cm ^-1 was selected, and the correlation between the real part of the dielectric function and the oxygen concentration at this wave number was confirmed. However, any wave number (for example, 800 cm ^-1 , 900 cm
It is clear that the correlation can be confirmed even if ^-1 ) is selected as an arbitrary wave number, and the difference in oxygen concentration with respect to the difference in the intensity of the real part of the dielectric function is clearer on the lower wave number side.

By preparing 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 in a non-contact and non-destructive manner thereafter. That is, if a 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.

Thus, three silicon wafers (resistivity 0.015 Ω · cm) of unknown oxygen concentration were irradiated with light having 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 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.

Prior to the completion of the present invention, there has been no example of taking a dielectric function spectrum in the infrared region of a semiconductor silicon crystal doped with boron or the like at a high concentration. And the oxygen concentration were not known at all. The present invention is characterized in that it has been confirmed for the first time to obtain an oxygen concentration using the dielectric function in the infrared region.

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

For example, in the above embodiment, an infrared spectroscopic ellipsometer is given as an example of a device for measuring a dielectric function. However, as can be seen from the principle, any device capable of measuring a dielectric function in the infrared region with high accuracy can be used. It is not limited.

[0054]

According to the present invention, a semiconductor silicon crystal has 20
Irradiate light containing an arbitrary wave number of not more than 00 cm ^−1, obtain a dielectric function real part at the arbitrary wave number from an amplitude ratio ψ and a phase difference Δ of the reflected light to the irradiation light, and obtain the semiconductor silicon crystal from this value. It is characterized by the evaluation of the oxygen concentration contained therein, so even if 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. In addition, it became possible to evaluate the oxygen concentration in the semiconductor crystal with high sensitivity and high reproducibility at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of an apparatus for performing 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 body, 3 ‥‥ Irradiation light, 4 ‥‥ Polarizer,
5 ‥‥ photo elastic modulator, 6 ‥‥ reflected light, 7 ‥‥ analyzer, 8 ‥‥ monochromator, 9 ‥‥ detector, 10 ‥‥ personal computer, 11 ‥‥ light source.

Claims (7)

[Claims] 1. A semiconductor silicon crystal having a thickness of 2000 cm ^-1
Irradiate light containing any of the following wave numbers, determine 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 from this value included in the semiconductor silicon crystal. A method for evaluating the oxygen concentration of a semiconductor silicon crystal, comprising: evaluating the oxygen concentration of a semiconductor silicon crystal. 2. A method for irradiating a plurality of semiconductor silicon crystals having known oxygen concentrations different from each other with light having an arbitrary wave number of 2000 cm ^-1 or less, and an amplitude ratio of reflected light to the irradiated light.
2. The correlation between the oxygen concentration at the given wave number and the real part of the dielectric function at the given wave number is determined in advance by obtaining the dielectric function real part of the arbitrary wave number at each oxygen concentration from the phase difference Δ. Oxygen concentration evaluation method. 3. The semiconductor silicon crystal having a resistivity of 1
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. The real part of the dielectric function at the arbitrary wave number is obtained by measuring an amplitude ratio ψ and a phase difference Δ of the reflected light to the irradiation light using an infrared spectroscopic ellipsometer. 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 chemical etching treatment. 7. A semiconductor silicon crystal having a thickness of 2000 cm ^-1
Irradiating means for irradiating light having any of the following wave numbers; measuring means for detecting reflected light from the semiconductor silicon crystal and measuring an amplitude ratio ψ and a phase difference Δ from the detected reflected light; An evaluation means for evaluating the concentration of oxygen contained in the semiconductor from the amplitude ratio ψ and the phase difference Δ.