JPH09260450A - Carbon density measurement of silicon crystal and carbon-free standard sample therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable measurement of even a low density of carbon with high precision, by adjusting and controlling the resistivity of a carbon-free standard sample in response to the resistivity of a silicon crystal to be measured. SOLUTION: In measurement of the carbon density in a silicon crystal by a Fourier transform infrared spectroscopy, the resistivity of a carbon-free standard sample is adjusted and controlled in response to the resistivity of a silicon crystal to be measured. Thus, since the carbon-free standard sample used as a reference is controlled in doping so as to have a resistivity corresponding to the resistivity of the silicon crystal to be measured, infrared absorption other than infrared absorption by carbon appearing around 600cm<-1> may be offset and the base line may be horizontally stabilized. Thus, the carbon density in the silicon crystal to be measured may be measured with high precision from an infrared absorption peak to a low density.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for measuring a silicon crystal carbon concentration and a carbon-free standard sample therefor, more specifically, Fourier transform infrared spectroscopy (FT-IR).
TECHNICAL FIELD The present invention relates to a silicon crystal carbon concentration measuring method capable of measuring a carbon concentration in a silicon crystal to a lower concentration than ever before using a method and a carbon-free standard sample therefor.

[0002]

2. Description of the Related Art A silicon single crystal forming a substrate of a semiconductor device is free from impurities as long as high purity is required. In semiconductors, even if the amount of impurities is extremely small, the final performance may be greatly affected. Especially, with the recent trend toward ultra-high integration, the demand for high-purity silicon single crystal as a substrate is extremely strict. It has become.
However, in the present circumstances, it is inevitable that various operations in the manufacturing process and the inclusion of an extremely small amount of impurities from the apparatus and the like cannot be avoided. Therefore, it is also possible to preliminarily measure the type and content of impurities contained in a silicon crystal for a semiconductor substrate, appropriately select various treatments based on the measurement result, and predict the performance of the obtained device. It is being appreciated. For this reason, improvements in various measuring instruments and improvements in measurement accuracy have been proposed for measuring impurities in silicon crystals, and there is always a demand for them.

[0003]

Under the circumstances as described above, the inventors of the present invention have found that the substitutional carbon in the silicon crystal is related to whether or not the electrical characteristics of the semiconductor element are good or bad. The purpose was to accurately measure the amount. The inventors first decided to fundamentally review the conventional method of measuring the concentration of substitutional carbon in a silicon crystal by the FT-IR method. The substitutional carbon concentration measurement by the FT-IR method that has been conventionally performed is performed as follows in a relative comparison with a standard sample that is free from impurities, like the components in other compounds. That is, a silicon crystal to be measured for measuring carbon concentration is formed on a disk-shaped measurement sample having a thickness of about 2 mm. The amount of transmitted infrared light is measured by measuring the measurement sample at a normal incidence in the thickness direction. Next, similarly, regarding a disk-like carbon-free standard sample (carbon content of less than about 1 × 10 ¹⁵ atoms / cm ³ ) having a thickness of 2 mm, the amount of infrared transmitted light was similarly measured by normal incidence measurement in the thickness direction. taking measurement. A difference absorbance spectrum is obtained from the difference in the amount of transmitted light between the two. Difference absorbance spectrum 604
The carbon concentration of the silicon crystal to be measured is determined from the infrared absorption peak of the substitutional carbon at cm ^-1 .

[0004] According to the inventors, the conventional FT-IR method as described above, carbon absorption peak of 604cm ^-1 is the absorption peak due to a silicon lattice vibrations (615 cm ^-1) is present in the vicinity thereof Also, since the absorption of carriers is affected by the strong absorption due to silicon lattice vibration, it is difficult to accurately determine the baseline, and the concentration measurement by the carbon absorption peak is not accurate, especially when the concentration is low. It was confirmed that it was difficult to meet the requirements. Therefore, the inventors have studied to find a method that can easily and more accurately measure the substitutional carbon concentration in a silicon crystal by using the FT-IR method, which has already been widely used. As a result, Czochralski (C
The single crystal silicon pulled up by the Z) method contains elements such as phosphorus, arsenic, and boron added to correspond to an n-type or p-type semiconductor and has a resistivity of not more than a predetermined value. Wave number 600 where the external absorption peak appears
It was found that the base line cannot be specified because the dent occurs near the lattice vibration peak of silicon in the vicinity of cm ^-1 , and the carbon concentration cannot be measured accurately. That is, the absorption due to the lattice vibration of the silicon is extremely large, while the absorption due to the carrier is comparatively small, and a dent occurs near 610 to 630 cm ^-1 of the differential absorption spectrum due to the influence of multiple reflection in the vertical incidence method. However, the baseline of the carbon infrared absorption peak cannot be specified. Based on this finding, the inventors
Floating zone (FZ), which was used as a reference, was investigated by examining infrared absorption near cm ^-1.
Replace with a high-purity, carbon-free standard sample with no dopant added (usually having a resistivity of about 1 kΩcm) produced from a silicon single crystal produced by the method, and make it correspond to the resistivity of the measured silicon crystal. The inventors have found that by using a carbon-free silicon single crystal pulled up by the CZ method in which the doping is controlled to a predetermined value as a reference, it is possible to accurately measure even a low concentration of carbon, and the present invention has been completed.

[0005]

According to the present invention, in the measurement of carbon concentration in a silicon crystal by Fourier transform infrared spectroscopy, a carbon-free standard sample of a carbon-free standard sample is obtained in accordance with the resistivity of the silicon crystal to be measured. There is provided a silicon crystalline carbon concentration measuring method characterized by adjusting and controlling a resistivity. In the silicon crystalline carbon concentration measuring method of the present invention, it is preferable that the resistivity of the carbon-free standard sample be doped and adjusted and controlled.

According to the present invention, a carbon-free standard sample for measuring silicon crystal carbon concentration by Fourier transform infrared spectroscopy, which corresponds to the n-type or p-type of a silicon crystal to be measured and its resistivity. A carbon-free standard sample for measuring the concentration of silicon crystalline carbon, which is controlled in doping, is provided. In the carbon-free standard sample for measuring the silicon crystal carbon concentration of the present invention, the doping control of the carbon-free standard sample is such that when the measured silicon crystal is n-type and the resistivity thereof is 1.5 Ωcm or more, non-doping is performed. , Less than 1.5 to 1.0 Ωcm, less than 1.0 to 0.5 Ωc so that n type has a resistance of 1.5 Ωcm.
m is preferably controlled so that the n-type becomes 1.0 Ωcm, and when the silicon crystal to be measured is p-type and the resistivity thereof is 20 Ωcm or more, non-doping is less than 20. 2 at p type at 15 Ωcm
0 Ωcm, less than 15 to 10 Ωcm p-type at 15 Ωcm, less than 10 to 5 Ωcm p
Less than 1.5 to less than 1.0 Ω, less than 5 to less than 1.5 Ωcm for p-type less than 1.5 to less than 1.0 Ω
cm, p-type has a resistance of 1.5 Ωcm, and less than 1.0 to 0.5 Ωcm has a p-type of 1.0 Ωcm.
Each is preferably controlled.

[0007] The present invention is configured as described above, standard samples of carbon-free use as references, from being doped controlled to have a resistivity corresponding to the resistivity of the measured silicon crystal, 600 cm ^-1 vicinity The infrared absorption other than the infrared absorption caused by carbon can be canceled out, the baseline is stabilized horizontally, and the carbon concentration in the measured silicon crystal can be accurately measured from the infrared absorption peak of carbon to a low concentration. You can Further, as described above, in order to accurately measure the substitutional carbon concentration in the silicon crystal to a low concentration by the FT-IR method, n-type or p-type of the measured silicon crystal and n corresponding to the resistivity thereof are measured.
Alternatively, the predetermined doping-controlled carbon-free standard sample of the present invention, which requires a reference having p-type and resistivity, has a resistivity value within a predetermined range corresponding to the n-type or p-type of the silicon crystal to be measured. Since it can be classified and prepared in advance so as to have the resistivity corresponding to each range, the carbon concentration in the silicon crystal of various resistivity can be easily measured by the FT-IR method.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION First, it will be described how the inventors have reached the present invention in which the resistivity of a carbon-free standard sample is controlled by doping in accordance with the resistivity of a silicon crystal to be measured. It is well known that the infrared absorption peak of carbon is 604 cm ^-1 , and it was easily presumed that it is affected by the absorption peak appearing in the vicinity thereof. Therefore, firstly, in the infrared absorption spectrum of the silicon single crystal, 600
The elements that generate infrared absorption in the vicinity of cm ^-1 were examined. The following three elements were mainly used: (i) infrared absorption by carriers, (ii) infrared absorption by lattice vibration of silicon crystals, and (iii) substitution type The study was based on the fact that it is dominated by infrared absorption by carbon. In addition, it was confirmed that each element has the following characteristics.

(I) Infrared absorption by carrier (α _e ) Since a silicon single crystal for semiconductors usually changes electric resistivity, as described above, it belongs to a group 3 or 5 group such as phosphorus, arsenic and boron. Adding a small amount of an element as a dopant,
Type and p-type semiconductors. The infrared absorption by the carrier of the added dopant can be calculated by the following formula 1 according to the carrier concentration. In the following formula 1, each coefficient is α _e (ν): absorption coefficient of carrier, ν: wave number, κ: relative permittivity of silicon, N: carrier concentration, μ: carrier mobility, m ^* : effective carrier Mass, ε ₀ : vacuum permittivity, c: speed of light in vacuum, δ ₀ :
Indicates electrical conductivity.

[0010]

[Equation 1]

In the above equation 1, the absorption coefficient α _e (ν) and the wave number ν (cm ^-1 ) were calculated for the cases where the silicon crystal resistivity is 1 Ωcm and 1 KΩcm, and the relationship is shown in FIG. As a result, the infrared absorption by the carrier increases as the carrier concentration in the silicon single crystal increases. That is, the lower the resistivity, the greater it becomes.
It became clear that the lower the wave number, the greater the absorption.

(Ii) Infrared absorption due to silicon crystal lattice vibration (α _p ) The infrared absorption coefficient α _p (ν) due to the lattice vibration of silicon crystal was measured, and the result is shown in FIG. It was also confirmed from this that, as is well known, infrared absorption having a large peak centered around 614 cm ⁻¹ occurs, as is well known.

(Iii) Infrared absorption by substitutional carbon in silicon crystal (α _c ) The infrared absorption coefficient α _c (ν) of substitutional carbon has a peak at 604 cm ⁻¹ , which depends on the lattice vibration of the silicon crystal. It is already well known that the infrared absorption coefficient is extremely smaller than the infrared absorption coefficient α _p (ν).

The infrared absorption spectrum near 600 cm ^-1 in the infrared absorption spectrum of the silicon single crystal for semiconductor has the above-mentioned 3
The elements are mainly, and in the measurement of infrared absorption spectrum, the sum of the infrared absorption coefficients of each element α = α _e (ν) + α _p (ν)
+ Α _c (ν) will be involved. On the other hand, when the amount of transmitted light is measured by vertically injecting infrared light into a measurement sample in which a silicon single crystal manufactured by the CZ method is formed into a disc shape with a thickness of 2 mm, the amount of transmitted light (I) is the multiple reflection on the surface. Therefore, it is represented by the following mathematical formula 2. In Formula 2, I represents the amount of transmitted light, I ₀ represents the amount of incident light, d represents the thickness of the sample, and R represents the reflectance of silicon.

[0015]

[Equation 2]

The differential absorption spectrum A can be expressed by the following expression 3 from the amount of transmitted light between the silicon crystal sample sample to be measured and the carbon free reference of the standard sample. In Equation 3, I _sam represents the transmitted light amount of the sample, and I _ref represents the transmitted light amount of the carbon free reference. Formula 3: A = log (I _sam / I _ref ) ⁻¹

Next, the influence of changes in the three elements of infrared absorption was examined. That is, regarding the mechanism of infrared absorption by carriers in the silicon single crystal by the CZ method,
The infrared absorption in the vicinity of 600 cm ⁻¹ was regarded as the sum α = α _e (ν) + α _p (ν) + α _c (ν) of the infrared absorption coefficients of the above three elements, and the simulation was performed and considered. Moreover, when the resistivity of the sample and the carbon-free reference were changed, the infrared absorption spectrum A was simulated and considered. That is, the carbon concentration is free, that is, zero, and a silicon single crystal sample to be measured having a thickness of 2 mm and a resistivity of 1 Ωcm (phosphorus-doped) is similarly used as a standard sample reference having a thickness of 2 mm and a resistivity of 1 Ωcm (phosphorus-doped). The differential absorption spectrum A was simulated in the vicinity of 600 cm ⁻¹ under the condition that the above ( ¹ ) was used. As a result, it was confirmed that the baseline was horizontal as shown in FIG.

On the other hand, similarly, the carbon concentration is free and the thickness is 2 mm.
Then, with respect to the reference having the resistivity of 1 Ωcm (phosphorus-doped) and the reference of the resistivity of 1 kΩcm (n type), the differential absorption spectrum A was simulated at about 600 cm ⁻¹ , and the result was calculated by measuring the absorbance (solid line) and the multiple reflection component. Absorbance without adding multiple reflection components (dashed line)
Is shown in FIG. According to FIG. 4, it becomes clear that the lower the wave number is, the higher the absorbance becomes, and the baseline is inclined. In addition, in the region of about 610 cm ⁻¹ to about 620 cm ⁻¹ , the absorbance, that is, the infrared ray including the multiple reflection component, is increased. It is clear that the absorption has a large dent, and as a result of the dent, the absorbance with the multiple reflection component added is almost the same as the absorbance without the multiple reflection component added. Further, the dent of the differential absorbance by this simulation may coincide with the large infrared absorption peak region based on the lattice vibration of silicon shown in FIG. 2 of the infrared absorption spectrum of the silicon crystal obtained by the above-mentioned actual measurement. it is obvious.

From these simulations and measured data, since the infrared absorption α _p due to the lattice vibration of silicon is strong and large, multiple reflection occurs in the 610 to 620 cm ⁻¹ region dominated by the lattice vibration infrared absorption α _p of this silicon. Is suppressed and the absorption due to the multiple reflection due to the lattice vibration absorption of the sample of the silicon crystal to be measured and the carrier absorption of the dopant becomes weak, so that it is clarified that the multiple reflection is hardly affected. On the other hand, 610 other than the above area
Because cm ^-1 in the following and 620 cm ^-1 or more regions not governed by the infrared absorption alpha _p is weak smaller silicon lattice vibration infrared absorption alpha _p due to lattice vibrations of the silicon, the 61
Contrary to the 0-620 cm ⁻¹ region, the effect of multiple reflection is high, and the absorption due to multiple reflection in the sample of the silicon crystal to be measured becomes strong. As a result, the value of α _p is small 61
In the region of 0 cm ^-1 or less and 620 cm ^-1 or more,
As described above, by simulating Equation 1, the absorption line of the carrier absorption α _e becomes continuously stronger as the wave number becomes lower. From the result that the absorption line of the carrier absorption α _e that does not add the multiple reflection component if absorbance line and baseline, in 610 cm ^-1 or less and 620 cm ^-1 or more areas, only absorption amount based on the multiple reflection by the phonon and carrier absorption of the measured silicon crystal sample, the 61
It is confirmed that the absorbance is stronger than that in the ⁰ to 620 cm ⁻¹ region. Therefore, assuming that the infrared absorption of the carbon-free reference having a resistivity of 1 kΩcm is only the phonon of silicon, the following formula 4 is obtained by substituting the transmitted light amount into the formula 3 of the differential absorption spectrum A.

[0020]

(Equation 4)

When the value of α _p in Equation 4 becomes small, the value of the second term on the right side becomes large and the value of absorbance also becomes large. Therefore, it is proved that the above consideration is correct in the calculation equation. According to these results, the value of the differential absorbance spectrum A is 610 by setting the absorbance curve without adding multiple reflection components as the baseline as shown in FIG.
Since the value of the absorbance in cm ^-1 or less and 620 cm ^-1 or more areas is increased, i.e., the slope of small weak infrared absorption peak appears 604cm ^-1 absorbance strong absorption before and after the region by carbon is greatly changed Therefore, it is clear that the measurement accuracy of the carbon concentration, particularly the low carbon concentration, decreases.
That is, when measuring the carbon concentration, by setting the resistivity of the sample and the reference to be the same or very close,
The multiple reflection components of the absorbance of the sample and the reference are almost the same value, and the baseline when looking at the difference between the two is approximated by a straight line, so it is possible to improve the measurement accuracy of the carbon concentration and the measured data and the above It is clear from the simulation result by the mathematical formula. Further, this is supported by the following examples. The reference standard sample used in the present invention is made to correspond to the n-type or p-type of the silicon crystal to be measured and the resistivity thereof as described above, and when the silicon crystal to be measured has a specific resistance or more, As a reference standard sample, a carbon-free (less than 1 × 10 ¹⁵ atoms / cm ³ ) silicon single crystal obtained by the FZ method can be used. On the other hand, when the silicon single crystal to be measured has a resistivity lower than a predetermined value, the reference standard sample is adjusted to n-type or p-type with a predetermined carrier element corresponding to the silicon crystal to be measured, and has a corresponding resistivity. It is possible to use a carbon-free silicon single crystal that is manufactured by the CZ method, whose concentration is adjusted to a predetermined value so as to be adjusted and controlled by doping. In this case, substantially 1 × 10 ¹⁵ atoms / cm ³
It is preferable to use a silicon single crystal manufactured by the CZ method that is pulled up in an environment where carbon is not mixed as much as possible so that the carbon content is less than less, and a head portion having a further lower carbon concentration.

[0022]

EXAMPLES The present invention will be described in more detail based on examples. However, the present invention is not limited to the following examples. Example 1 A carbon-free (carbon concentration of less than 1 × 10 ¹⁵ atoms / cm ³ ) non-doped silicon wafer (S1) manufactured from an FZ method silicon single crystal and phosphorus (P) by the CZ method were used. The resistivity of an n-type silicon wafer manufactured from a silicon single crystal added as a dopant is 1.575 Ωcm (S2),
1.46 Ωcm (S3), 1.324 Ωcm (S4),
0.851 Ωcm (S5), substitutional carbon concentration of about 1
× 10 ¹⁵ atoms / cm ^{3 to} 5 × 10 ¹⁵ atoms /
Five samples of cm ³ n-type silicon wafers were prepared.
S1 is used as a reference standard sample, S2, S
F for silicon wafers S3, S4 and S5 respectively
Infrared absorption was measured by the T-IR method. The obtained differential absorption spectra are shown in FIGS. 5 to 8.

As is clear from the results shown in FIGS.
In the silicon wafers with a resistivity of up to about 1.5 Ωcm of 1 and S2, no dent was generated near 614 cm −1 of the lattice vibration of silicon, but with the silicon wafers of S3 and S4 with a resistivity of 1.4 Ωcm or less, it gradually became. It can be seen that there is a dent. In the infrared absorption measurement by the FT-IR method of the silicon wafer having the resistivity in which the generation of such a dent is observed, the carbon-free silicon wafer having the same resistivity as the reference of the standard sample is determined from the above-mentioned results. It turns out that it needs to be used.

Next, a silicon wafer was manufactured by cutting from a head portion of a CZ method silicon single crystal doped with phosphorus so that the resistivity was about 0.8 Ωcm. Using the obtained carbon-free n-type silicon wafer having a resistivity of 0.874 Ωcm as a reference, infrared absorption was similarly measured for the silicon wafer of S5. The results are shown in Fig. 9. As is clear from FIG. 9, the silicon lattice vibration absorption region 614c can be formed by using a carbon-free silicon wafer having substantially the same resistivity as the reference.
It can be seen that the dent near m ⁻¹ disappears, the baseline becomes almost horizontal, the infrared absorption peak at 604 cm ⁻¹ by the substitutional carbon becomes sharp, and the concentration measurement becomes easy.

Example 2 A p-type silicon wafer manufactured from a silicon single crystal doped with boron (B) as a dopant by the CZ method has a resistivity of 20.4 Ωcm (S6) and 10.12 Ωc, respectively.
m (S7), the substitutional carbon concentration is about 3 × 10 ¹⁶ ato
Example 1 for a p-type silicon wafer of ms / cm ³
Infrared absorption was measured by the FT-IR method using S1 as a reference similarly to. The obtained differential absorption spectra are shown in FIG. In FIG. 10, S of 20.4 Ωcm
It can be seen that in No. 6, no dent is generated near 614 cm ^-1 , but in S7, a large dent is generated. The p-type silicon wafer has larger depressions in the silicon lattice vibration absorption region than the n-type because the absorption coefficient of the p-type carrier B is large.

Further, a silicon wafer was manufactured by cutting out from a head portion of a CZ method silicon single crystal doped with boron so as to have a resistivity of about 10 Ωcm. Using the obtained carbon-free silicon wafer having a resistivity of 10.25 Ωcm as a reference, infrared absorption was similarly measured for the silicon wafer of S7. The result is shown in FIG.
It was shown to. As is clear from the results of FIGS. 10 and 11,
Also in the p-type silicon wafer, the resistivity of the standard sample used for the reference of the infrared absorption carbon concentration measurement by the FT-IR method is made almost the same as the resistivity of the silicon wafer to be measured, so that the baseline is almost leveled and the carbon is leveled. It can be seen that the infrared absorption peak can be used for concentration measurement.

From the above results, the FT- of the silicon wafer
In the infrared absorption carbon concentration measurement by the IR method, when the silicon wafer to be measured has a resistivity of up to about 1.5 Ωcm for the n-type and a resistivity of up to about 20 Ωcm for the p-type silicon wafer, a non-doped sample of about several kΩcm is used as a standard sample. High-resistivity carbon-free silicon wafer can be used as a reference, but in the case of measurement of silicon wafers having lower resistivity, that is, higher carrier concentration, carbon-free silicon wafers are doped with a carrier element respectively. By using the silicon wafer with a resistivity almost equal to that of the measurement silicon wafer, a stable horizontal baseline can be secured without forming a dent in the silicon lattice vibration absorption region, and a sharp carbon peak can be obtained for concentration measurement. Obviously it will be easier.

[0028]

According to the method for measuring the concentration of silicon crystal carbon of the present invention, when the concentration is quantitatively measured from the infrared absorption carbon peak by the FT-IR method, a predetermined value is determined so as to correspond to the resistivity of the silicon crystal to be measured. By using a standard sample with resistivity, the baseline, which was difficult to identify in the conventional method, can be leveled, so particularly low carbon concentration can be measured accurately and accurately, and any carbon concentration can be measured accurately. can do. In addition, since a carbon-free standard sample having a predetermined resistivity corresponding to the resistivity of each silicon crystal can be prepared in advance, it is easy and easy to perform FT-
The carbon concentration of silicon crystals can be measured by the IR method.

[Brief description of drawings]

FIG. 1 is a relationship diagram obtained by calculating an infrared absorption coefficient and a wave number depending on a carrier concentration in a silicon crystal.

[Fig. 2] Actual measurement relationship diagram between infrared absorption coefficient and wave number due to silicon lattice vibration

FIG. 3 is an infrared absorption curve of a simulation result in the vicinity of 600 cm ⁻¹ so that the resistivity of the silicon to be measured is made to correspond to that of the standard sample.

FIG. 4 is a diagram in which multiple reflection components are added or not added without making the resistivity of the silicon to be measured and the standard sample correspond to each other.
Infrared absorbance curve of simulation result near 0 cm ^-1

FIG. 5: Silicon wafer S measured in Example 1 of the present invention
2 infrared absorption curve

FIG. 6 is a silicon wafer S measured in Example 1 of the present invention.
Infrared absorbance curve of 3

FIG. 7: Silicon wafer S measured in Example 1 of the present invention
4 infrared absorption curve

FIG. 8 is a silicon wafer S measured in Example 1 of the present invention.
Infrared absorption curve of 5

FIG. 9 is an infrared absorption curve of an n-type silicon wafer measured by the FT-IR method using a carbon-free silicon wafer having the same resistivity as a standard sample.

FIG. 10 is an infrared absorption curve when the resistivity of the p-type silicon to be measured is changed.

FIG. 11 is an infrared absorption curve of a p-type silicon wafer measured by the FT-IR method using a carbon-free silicon wafer having an equivalent resistivity as a standard sample.

Claims (5)

[Claims] 1. When measuring the carbon concentration in a silicon crystal by Fourier transform infrared spectroscopy, the resistivity of a carbon-free standard sample is adjusted and controlled according to the resistivity of the silicon crystal to be measured. A method for measuring a low carbon concentration in a silicon crystal characterized by: 2. The silicon crystalline carbon concentration measuring method according to claim 1, wherein the resistivity of the carbon-free standard sample is adjusted and controlled by doping. 3. A carbon-free standard sample for measuring silicon crystal carbon concentration by Fourier transform infrared spectroscopy,
A carbon-free standard sample for measuring the silicon crystal carbon concentration, which is controlled in doping according to the n-type or p-type of the measured silicon crystal and its resistivity. 4. The doping control of the carbon-free standard sample is performed by non-doping when the measured silicon crystal is n-type and the resistivity thereof is 1.5 Ωcm or more.
If less than 5 to 1.0 Ωcm, n type is 1.5 Ωcm. If less than 1.0 to 0.5 Ωcm, n type is 1.0 Ωc.
The carbon-free standard sample for measuring the silicon crystalline carbon concentration according to claim 3, wherein the carbon-free standard sample is controlled so as to have m. 5. The doping control of the carbon-free standard sample is controlled to be non-doping when the measured silicon crystal is p-type and the resistivity thereof is 20 Ωcm or more.
Less than 15 Ωcm, so that the p-type becomes 20 Ωcm,
If it is less than 15 to 10 Ωcm, it becomes 15 Ωcm in p type, if it is less than 10 to 5 Ωcm, it becomes 10 Ωcm in p type, if it is less than 5 to 1.5 Ωcm, it becomes 5 Ωcm in p type, and less than 1.5 to 1 1.5Ω for p-type at 0.0Ωcm
4. The carbon-free standard sample for measuring the silicon crystalline carbon concentration according to claim 3, wherein the carbon-free standard sample is controlled so that it becomes less than 1.0 cm and less than 1.0 Ωcm, and p-type becomes 1.0 Ωcm.