JP2000188313A - Evaluation method for silicon substrate and manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an evaluation method for a silicon substrate, which can easily and quantitatively evaluate the gettering capability of even a silicon substrate having a low specific resistance value and the manufacture of a semiconductor device using a silicon substrate similar to a sample substrate evaluated by the evaluating method. SOLUTION: A lithium-oxygen complex is formed by introducing lithium into a silicon substrate containing acceptor impurities of 1017 cm-3 and oxygen of 1016 cm-3 and the half-value width (w) of an infrared absorption peak characteristic of the lithium-oxygen complex is measured so as to evaluate the gettering capability of the silicon substrate. Then the half-value width of an infrared absorption peak in a wave-number area of 1083±5 cm-1 is measured. Furthermore, the half-value width W of an absorption peak is measured, while the temperature of the silicon substrate is held below 40 K.

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 silicon substrate and a method for manufacturing a semiconductor device, and more particularly to a method for evaluating a silicon substrate which can easily evaluate the gettering ability of impurities, and a method for evaluating the same. The present invention relates to a method for manufacturing a semiconductor device using a silicon substrate similar to a sample substrate evaluated using the same.

[0002]

2. Description of the Related Art In a process of forming a semiconductor element on a silicon substrate, impurities such as heavy metal elements may be mixed into the silicon substrate. Such impurities such as heavy metal elements have a significant effect on the electrical characteristics of the semiconductor device. Therefore, a technique has been known in which impurities such as heavy metal elements are captured in a silicon substrate by generating oxygen precipitates in a deep region from the surface of the silicon substrate in advance. If oxygen precipitates are generated in the silicon substrate, a strain field is generated in the crystal structure around the oxygen precipitates, and impurities can be captured by the strain fields.

[0003] If impurities such as heavy metal elements are captured in the silicon substrate, a region near the surface of the silicon substrate, that is, a region where a semiconductor element is formed is brought into a clean state. In order to make a region where a semiconductor element is formed as clean as possible, it is important to use a silicon substrate having high gettering ability. When a semiconductor element is formed using a silicon substrate having high gettering ability, a semiconductor device can be manufactured with high yield.

As a method for evaluating the gettering ability of a silicon substrate, the following evaluation method has been proposed. The first evaluation method is a method for evaluating the gettering ability of a silicon substrate based on the density of etch pits generated. That is, first, oxygen precipitates intentionally contaminate the silicon substrate formed therein with impurities. Then, impurities are captured by applying heat treatment to the contaminated silicon substrate. Then, the surface of the silicon substrate is etched. Since the impurities not captured in the silicon substrate are deposited on the surface of the silicon substrate, etching pits are generated on the surface of the silicon substrate in accordance with the precipitated impurities when etching having plane anisotropy such as SECCO etching is performed. In a silicon substrate having a high gettering ability, since impurities are captured in the silicon substrate, the generation density of etch pits on the surface of the silicon substrate is low. On the other hand, in a silicon substrate having a low gettering ability, impurities are less likely to be trapped in the silicon substrate, so that the density of etch pits formed on the surface of the silicon substrate is high. Therefore,
The gettering ability of the silicon substrate can be evaluated by measuring the generation density of the etch pits on the surface of the silicon substrate.

The second evaluation method is a method for evaluating the gettering ability of a silicon substrate by observing the size and density of oxygen precipitates in the silicon substrate using an optical microscope. That is, a crystal strain field is generated around the oxygen precipitate generated in the silicon substrate, and impurities are captured in the silicon substrate according to the strain field. Therefore, by observing the size and density of the oxygen precipitate generated in the silicon substrate with an optical microscope, the gettering ability of the silicon substrate can be evaluated.

The third evaluation method is a method for evaluating the gettering ability of a silicon substrate by reducing the peak value of an infrared absorption spectrum. Isolated interstitial oxygen, that is, oxygen in a silicon substrate that is not precipitated as oxygen precipitates, vibrates at a specific frequency and absorbs infrared rays. For example, at room temperature, an infrared absorption peak exists at a wave number of about 1106 cm ^-1 . When heat treatment is performed to improve the gettering ability of the silicon substrate, the concentration of isolated interstitial oxygen in the silicon substrate becomes low because isolated interstitial oxygen is precipitated in the silicon substrate as oxygen precipitates. The peak value of the infrared absorption spectrum by isolated interstitial oxygen becomes low. Therefore, by measuring the decrease in the peak value of the infrared absorption spectrum, it is possible to estimate the generation amount of oxygen precipitates, and thereby to evaluate the gettering ability of the silicon substrate.

[0007]

However, in the above-mentioned first evaluation method, it is possible to evaluate the gettering ability in the case of a silicon substrate contaminated with a high concentration, but it is possible to evaluate the gettering ability with a silicon substrate contaminated with a high concentration. It was difficult to evaluate the gettering ability of the silicon substrate. Further, the generation density of the etch pits varies depending on the temperature conditions at the time of etching, the type of chemical solution used for etching, and the like, and it has been difficult to quantitatively evaluate the gettering ability of the silicon substrate.

In the second evaluation method, only a large amount of oxygen precipitate that can be seen with an optical microscope can be observed, and even a small amount of oxygen precipitate having gettering ability can be observed. Did not. Therefore, it has been difficult to quantitatively evaluate the gettering ability of the silicon substrate. Further, the third evaluation method described above cannot evaluate the gettering ability of a low-resistance silicon substrate having a specific resistance of 1 Ω · cm or less, for example.
That is, in a low-resistance silicon substrate, acceptor impurities are introduced at a high concentration in order to lower the specific resistance value, and infrared rays are absorbed by carrier electrons generated from the acceptor impurities. Moreover, the infrared absorption peak due to such carrier electrons is about 1106 cm ^−1, which is similar to the infrared absorption peak due to isolated interstitial oxygen. Therefore,
In the third evaluation method, the gettering ability of the low-resistance silicon substrate could not be evaluated.

An object of the present invention is to provide a method for evaluating a silicon substrate which can easily and quantitatively evaluate gettering ability even with a silicon substrate having a low specific resistance value, and an evaluation method using the evaluation method. It is an object of the present invention to provide a method for manufacturing a semiconductor device using a silicon substrate similar to a sample substrate.

[0010]

SUMMARY OF THE INVENTION The above-mentioned object is to achieve the object of 10 ¹⁷ cm.
Lithium is introduced into a silicon substrate containing ^-3 or more acceptor impurities and 10 ¹⁶ cm ^-3 or more oxygen to form a lithium-oxygen complex in the silicon substrate, and a red color unique to the lithium-oxygen complex is formed. This is achieved by a method for evaluating a silicon substrate, wherein the gettering ability of the silicon substrate is evaluated by measuring a half width of an external absorption peak. Thereby, since lithium is introduced into the silicon substrate, the acceptor impurity is compensated by the lithium, and generation of carrier electrons from the acceptor impurity can be suppressed. Since the silicon substrate having a larger half-width of the infrared absorption peak after the gettering heat treatment tends to have higher gettering ability, the half-width of the infrared absorption peak after the gettering heat treatment is measured simply and quantitatively. The gettering ability of the silicon substrate can be evaluated. Moreover, in the lithium-oxygen composite, since lithium and oxygen simultaneously vibrate and the peak value of the infrared absorption spectrum becomes high, the gettering ability of the silicon substrate can be evaluated with high sensitivity.

In the above-described method for evaluating a silicon substrate, it is desirable to measure the half-width of the infrared absorption peak in a wavenumber range of about 1083 ± 5 cm ⁻¹ . In the above-described method for evaluating a silicon substrate, it is preferable to measure the half-value width of the infrared absorption peak by setting the temperature of the silicon substrate to 40 K or less. In the method for evaluating a silicon substrate, the silicon substrate is heat-treated to generate oxygen precipitates in the silicon substrate.
When the half-width of the infrared absorption peak of the silicon substrate after the heat treatment is 2.1 cm ⁻¹ or more, it is desirable that the silicon substrate be determined to be non-defective.

[0012] Further, the object is to prepare a plurality of p-type silicon substrates, extract one silicon substrate from the plurality of silicon substrates, introduce lithium into the one silicon substrate, and add lithium to the one silicon substrate. The gettering ability of the one silicon substrate was evaluated by binding the lithium to the oxygen and measuring the half width of an infrared absorption spectrum corresponding to the bond between the oxygen and the lithium, and the evaluation result was good. In this case, the present invention is achieved by a method for manufacturing a semiconductor device, wherein a semiconductor element is formed on another silicon substrate using another silicon substrate except the one silicon substrate. Thus, one silicon substrate is extracted from a plurality of silicon substrates manufactured in substantially the same process, and the silicon substrate is evaluated.If the evaluation result is good, the silicon substrate used in the evaluation is evaluated. If a semiconductor element is formed using a silicon substrate excepted, a semiconductor device can be manufactured with high yield.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Fourier Transform Infrared Spectroscopy Measuring Apparatus) First, a Fourier transform infrared spectroscopy measuring apparatus used in a silicon substrate evaluation method according to one embodiment of the present invention will be described with reference to FIG. I do. FIG. 1 is a block diagram showing a Fourier transform infrared spectroscopy measuring apparatus.

As shown in FIG. 1, a silicon substrate 10 as a sample substrate is fixed by a holder (not shown), and infrared rays 14 emitted from a light source 12 are irradiated with a beam splitter 1.
6 is incident. As a material of the beam splitter 16,
For example, potassium bromide (KBr) is used. Light source 12
The infrared light emitted from the optical system and transmitted through the beam splitter 16 enters a fixed mirror 18 and is reflected by the fixed mirror 18. The infrared light reflected by the fixed mirror 18 is
The light again enters the beam splitter 16, is reflected by the beam splitter 16, and enters the silicon substrate 10. The infrared light emitted from the light source and reflected by the beam splitter 16 is reflected by the movable mirror 20.
The infrared light reflected by the movable mirror 20 enters the beam splitter 16 again, passes through the beam splitter 16 and enters the silicon substrate 10. As described above, the infrared rays are superposed by the beam splitter 16 and enter the silicon substrate 10.

A part of the infrared light incident on the silicon substrate 10 passes through the silicon substrate 10. Silicon substrate 10
The infrared rays that have passed through generate an interference pattern in accordance with the optical path difference until they are superposed by the beam splitter 16.
This interference pattern is measured by the infrared detector 22, and the data of the detection result by the infrared detector 22 is output to the computer 24. The computer 24 performs a Fourier transform on the data input from the infrared detector 22. The result of the Fourier transform performed by the computer 24 is output from the recorder 26 as a graph showing an infrared absorption spectrum.

A specific example of a graph of an infrared absorption spectrum output from the recorder 26 will be described with reference to FIG. FIG.
3 is a graph showing a specific example of an infrared absorption spectrum measured using a Fourier transform infrared spectroscopy measuring apparatus as shown in FIG. The horizontal axis in FIG. 2 shows the wave number, and the vertical axis shows the infrared absorption intensity. As described above, the infrared absorption spectrum of the silicon substrate 10 can be measured by using a Fourier transform infrared spectroscopy measuring apparatus as shown in FIG.

(Method of Evaluating Silicon Substrate) Next, the method of evaluating the silicon substrate according to the present embodiment will be explained with reference to FIGS. FIG. 3 is a conceptual diagram showing a bonding state of isolated interstitial oxygen in a silicon substrate. FIG. 4 is a graph showing an infrared absorption spectrum of the silicon substrate. FIG. 5 is a graph showing the relationship between the half width of the infrared absorption peak and the gettering ability of the silicon substrate.

First, a low resistance CZ silicon substrate serving as a sample substrate is prepared. The conductivity type of the silicon substrate is p-type,
The thickness is, for example, 500 μm, and the specific resistance is, for example, 0.1 Ω ·
cm or less, the acceptor impurity introduced into the silicon substrate may be, for example, boron, and the concentration of the acceptor impurity may be, for example, 10 ¹⁷ cm ⁻³ or more. As the silicon substrate made of CZ, for example, a silicon substrate containing isolated interstitial oxygen at a concentration of 10 ¹⁶ cm ⁻³ or more can be used. The thickness, specific resistance, acceptor impurities, and the like of the silicon substrate are not limited to those described above, and the evaluation method of the silicon substrate according to the present embodiment can be applied to any silicon substrate. Next, lithium is introduced into the silicon substrate by immersing the silicon substrate in the Sn-Li solution. The temperature of the Sn—Li solution is, for example, 90
At 0 ° C., the lithium used for the Sn—Li solution is Li ⁷
Alternatively, it can be Li ⁶ . Note that both Li ⁶ and Li ⁷ may be used as lithium used in the Sn—Li solution.

By introducing lithium into the silicon substrate, the lithium compensates for the acceptor impurity, and the generation of carrier electrons from the acceptor impurity can be suppressed. When lithium is introduced into a silicon substrate having a specific resistance of, for example, 0.1 Ω · cm or less, the specific resistance of the silicon substrate is 0.1 Ω · cm or more, and the specific resistance of the silicon substrate is as high as possible. Thus, the silicon substrate is immersed in the Sn-Li solution. The specific resistance of the silicon substrate can be measured by a four-probe method.

If the p-type silicon substrate is immersed in the Sn-Li solution for a long time, the acceptor impurities are compensated by lithium, and the conductivity type of the silicon substrate approaches the n-type, and the specific resistance decreases. It is necessary to keep in mind. Also, the time required to reach a desired specific resistance value varies depending on the concentration of the acceptor impurity introduced into the silicon substrate and the like. Therefore, the time for immersing the silicon substrate in the Sn-Li solution also takes into account the concentration of the acceptor impurity. It is necessary to adjust accordingly. For example, the acceptor impurity introduced into the silicon substrate is boron, and the boron concentration is 10%.
When it is about ¹⁹ cm ^-3 , the time of immersion in the Sn-Li solution can be, for example, about 30 seconds. The amount of isolated interstitial oxygen that diffuses out of the silicon substrate when introducing lithium is sufficiently small and can be ignored.

The main feature of the method for evaluating a silicon substrate according to this embodiment is to evaluate the gettering ability by introducing lithium into the silicon substrate. On a silicon substrate into which lithium has not been introduced, isolated interstitial oxygen is shown in FIG.
It is bonded to silicon as shown in FIG. FIG.
(A) is a conceptual diagram showing a bonding state between silicon and isolated interstitial oxygen in a silicon substrate into which lithium has not been introduced. In FIG. 3A, acceptor impurities and oxygen precipitates in the silicon substrate are omitted.

As shown in FIG. 3A, in a silicon substrate into which lithium has not been introduced, isolated interstitial oxygen and silicon are in a bonded state of a Si--O--Si structure. When such a silicon substrate is irradiated with infrared rays, carrier electrons are generated from acceptor impurities. Since the wave number of the infrared absorption peak due to carrier electrons is substantially the same as the wave number of the infrared absorption peak due to isolated interstitial oxygen, it is difficult to measure the infrared absorption spectrum solely by isolated interstitial oxygen.

On the other hand, in the silicon substrate into which lithium has been introduced as in this embodiment, lithium is bonded to isolated interstitial oxygen as shown in FIG. 3B. FIG. 3 (b)
FIG. 3 is a conceptual diagram showing a bonding state between silicon, isolated interstitial oxygen, and lithium in a silicon substrate into which lithium is introduced. Lithium introduced into the silicon substrate is bonded to isolated interstitial oxygen with a probability of 90% or more. In FIG. 3B, the acceptor impurities and oxygen precipitates in the silicon substrate are omitted.

In a silicon substrate into which lithium has been introduced,
Since lithium compensates for the acceptor impurity, generation of carrier electrons from the acceptor impurity is suppressed.
On the silicon substrate into which lithium has been introduced, a Li-O complex as shown in FIG. Since the Li—O composite has an inherent vibration energy, a wavenumber region of 120 in a silicon substrate into which lithium is not introduced.
The infrared absorption peak appearing at 3 ± 5 cm ⁻¹ is in a wavenumber region of 1083 ± 5 cm on a silicon substrate into which lithium is introduced.
Shift to ^-1 . Therefore, for a silicon substrate into which lithium is introduced, an infrared absorption spectrum in a wavenumber range of 1083 ± 5 cm ⁻¹ may be measured.

In this embodiment, since lithium is introduced into the silicon substrate, oxygen and lithium simultaneously oscillate and generate a large dipole moment in a wave number region of 1083 ± 5 cm ^-1 . Since the infrared absorption peak is proportional to the square of the dipole moment, the peak value of the infrared absorption spectrum of a silicon substrate into which lithium is introduced is about five times that of a silicon substrate into which lithium is not introduced. Therefore, the silicon substrate into which lithium is introduced is about 5 times the silicon substrate into which lithium is not introduced.
The gettering ability can be evaluated with twice the sensitivity.

Next, the temperature of the silicon substrate is set to, for example, 40K.
Hereinafter, an infrared absorption spectrum in a wavenumber range of 1083 ± 5 cm ⁻¹ is measured using a Fourier transform infrared spectrometer. FIG. 4A shows a wave number range of 1083 ± 5.
4 is a graph showing an infrared absorption spectrum of a silicon substrate at cm ⁻¹ .

As shown in FIG. 4A, the gettering heat
Treatment, that is, heat treatment to enhance the gettering ability.
Before the measurement, the half width w of the infrared absorption peak is, for example, 2.0
cm ^-1It has become. Generally, a low-resistance p-type capacitor is used.
Wave number range 1083 ± 5cm^-1Red in
The half width of the external absorption peak is 2.0 cm^-1Is below
Often.

The reason why the temperature of the silicon substrate is set to 40 K or lower when measuring the infrared absorption spectrum is as follows. That is, at a high temperature of 40 K or more, since a large number of vibration modes occur in the wavenumber range of 1083 ± 5 cm ⁻¹ , the half width of the infrared absorption peak is widened, and the peak value of the infrared absorption spectrum is reduced. For this reason, it is difficult to obtain a stable infrared absorption spectrum. On the other hand, when the substrate temperature is set to 40 K or lower, the occurrence of many vibration modes is suppressed, the half-width of the infrared absorption peak is reduced, and the peak value of the infrared absorption spectrum is increased.
Therefore, by setting the temperature of the silicon substrate to 40 K or less, a stable infrared absorption spectrum can be measured.

The half width of the infrared absorption peak in the wavenumber range of 1083 ± 5 cm ^-1 corresponds to the size of the strain field region. Therefore, when evaluating the magnitude of the strain field around the oxygen precipitate, the evaluation is made not by the peak value of the infrared absorption spectrum but by the half width of the infrared absorption peak. In other words, by measuring the half width of the infrared absorption peak, the magnitude of the strain of the oxygen precipitate in the silicon substrate can be evaluated, and thereby the gettering ability of the silicon substrate can be evaluated.

Next, the silicon substrate is subjected to a gettering heat treatment, that is, a heat treatment for improving the gettering ability. The heat treatment conditions can be, for example, 700 ° C. and 128 hours. By performing such a heat treatment, oxygen precipitates are generated in the silicon substrate. FIG. 4 (b)
Wave number region 1083 of the silicon substrate on which oxygen precipitates are generated
4 is a graph showing an infrared absorption spectrum at ± 5 cm ⁻¹ . From FIG. 4B, when the half width of the infrared absorption peak is measured, for example, the half width w is 3.1 cm ⁻¹ .

The gettering ability of the silicon substrate is determined by the wave number
Area 1083 ± 5cm^-1Half width of infrared absorption peak in
Tend to be higher as is larger. Wave number range 1083 ± 5
cm ^-1Width of infrared absorption peak in silicon and silicon substrate
The relationship with the gettering ability will be described with reference to FIG.
FIG. 5 shows a wave number range of 1083 ± 5 cm.^-1Infrared absorption
The relationship between the half-width of the
It is a graph which shows a relationship. In FIG. 5, the horizontal axis is the wave number range 10
83 ± 5cm^-1Indicates the half width of the infrared absorption peak at
The vertical axis shows the Fe concentration on the surface of the silicon substrate.
I have.

The graph shown in FIG. 5 can be obtained as follows. That is, first, the surface of the silicon substrate is
Deliberately polluted by Fe, a heavy metal element. To contaminate the surface of the silicon substrate with Fe, for example, Fe
What is necessary is just to immerse the silicon substrate in an ammonia hydrogen peroxide solution containing (iron). When the silicon substrate is immersed in such a solution for 5 minutes, the surface of the silicon substrate becomes, for example, 10 ¹⁴ at.
Contaminated at a concentration of oms / cm ³ . In FIG. 5, it is shown as the initial contamination concentration.

After that, gettering heat treatment is performed on the silicon substrate. As a result, impurities are captured in the silicon substrate, and the impurity concentration on the silicon substrate surface decreases.
The heat treatment condition can be, for example, 1000 ° C. for one hour. Then, when the impurity concentration on the surface of the silicon substrate, specifically, the Fe concentration is measured after the gettering heat treatment,
The Fe concentration on the silicon substrate surface is as shown in FIG.
The Fe concentration on the silicon substrate surface is, for example, DLTS
(Deep Level Trasient Spectroscopy) method.

As shown in FIG. 5, a silicon substrate having a larger half-width of the infrared absorption peak has a lower Fe concentration. That is, as the silicon substrate having a larger half width of the infrared absorption peak in the wavenumber range of 1083 ± 5 cm ⁻¹ is used, the impurity concentration on the silicon substrate surface after the gettering heat treatment tends to be lower. Therefore, when a silicon substrate having a large half-width of the infrared absorption peak is used, the concentration of impurities such as heavy metals in the vicinity of the region where the semiconductor element is formed can be reduced, and a semiconductor device can be manufactured with high yield. It becomes possible.

As described above, according to the present embodiment, since lithium is introduced into the silicon substrate, the acceptor impurity is compensated for by the lithium, and generation of carrier electrons from the acceptor impurity can be suppressed. Since the silicon substrate having a larger half-width of the infrared absorption peak after the gettering heat treatment tends to have higher gettering ability, the half-width of the infrared absorption peak after the gettering heat treatment is measured simply and quantitatively. The gettering ability of the silicon substrate can be evaluated. In addition, since lithium introduced into the silicon substrate is bonded to isolated interstitial oxygen, lithium and the isolated interstitial oxygen simultaneously vibrate, generating a large dipole moment, thereby increasing the peak value of the infrared absorption spectrum. . Therefore,
The gettering ability of the silicon substrate can be evaluated with high sensitivity.

Further, one silicon substrate was extracted from a plurality of silicon substrates manufactured in the same process, and evaluated using the silicon substrate evaluation method according to the present embodiment. The evaluation result was good. In this case, when a semiconductor element is formed using a silicon substrate other than the silicon substrate used in the evaluation, a semiconductor device can be manufactured with high yield. For example, the half width after the gettering heat treatment is 2.
A case of 1 cm ⁻¹ or more can be determined as a good product. In addition, the half-value width serving as a criterion for quality determination is 2.1 cm ^-1.
The invention is not limited to the above, and a standard may be appropriately set.

[Modified Embodiment] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the above embodiment, a silicon substrate having a specific resistance of 0.1 Ω · cm or less was used. However, the present invention is not limited to a silicon substrate having a specific resistance of 0.1 Ω · cm or less. -It can be applied to a silicon substrate of cm or more.

In the above embodiment, a silicon substrate into which boron is introduced as an acceptor impurity is used. However, the acceptor impurity of the silicon substrate is not limited to boron. For example, Al, Ga, In, and Tl are acceptable. A silicon substrate introduced as an impurity may be used. Further, a silicon substrate into which Ge is introduced may be used.

[0039]

As described above, according to the present invention, since lithium is introduced into the silicon substrate, the acceptor impurity is compensated by the lithium, and the generation of carrier electrons from the acceptor impurity can be suppressed. Since the silicon substrate having a larger half-width of the infrared absorption peak after the gettering heat treatment tends to have higher gettering ability, the half-width of the infrared absorption peak after the gettering heat treatment is measured simply and quantitatively. The gettering ability of the silicon substrate can be evaluated. In addition, since lithium introduced into the silicon substrate bonds with isolated interstitial oxygen, the lithium and the isolated interstitial oxygen vibrate simultaneously, generating a large dipole moment, thereby increasing the peak value of the infrared absorption spectrum. Become. Therefore, the gettering ability of the silicon substrate can be evaluated with high sensitivity.

Further, according to the present invention, one silicon substrate is extracted from a plurality of silicon substrates manufactured in the same process and evaluated using the silicon substrate evaluation method according to the present embodiment. If the result is good, a semiconductor device can be manufactured with a high yield by forming a semiconductor element using a silicon substrate other than the silicon substrate used in the evaluation.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a Fourier transform infrared spectroscopy system measuring apparatus.

FIG. 2 is a graph showing a specific example of an infrared absorption spectrum.

FIG. 3 is a conceptual diagram showing a bonding state of isolated interstitial oxygen in a silicon substrate.

FIG. 4 is a graph showing an infrared absorption spectrum of a silicon substrate.

FIG. 5 is a graph showing the relationship between the half width of an infrared absorption peak and the gettering ability of a silicon substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Silicon substrate 12 ... Light source 14 ... Infrared 16 ... Beam splitter 18 ... Fixed mirror 20 ... Movable mirror 22 ... Infrared detector 24 ... Computer 26 ... Recorder

Claims (5)

[Claims] 1. A method according to claim 1, wherein lithium is introduced into a silicon substrate containing an acceptor impurity of 10 ¹⁷ cm ⁻³ or more and oxygen of 10 ¹⁶ cm ⁻³ or more to form a lithium-oxygen complex in the silicon substrate. -A method for evaluating a silicon substrate, wherein a gettering ability of the silicon substrate is evaluated by measuring a half width of an infrared absorption peak specific to the oxygen complex. 2. The method for evaluating a silicon substrate according to claim 1, wherein the half width of the infrared absorption peak in a wavenumber range of about 1083 ± 5 cm ⁻¹ is measured. 3. The method for evaluating a silicon substrate according to claim 1, wherein the half-width of the infrared absorption peak is measured by setting the temperature of the silicon substrate to 40 K or less. . 4. The method for evaluating a silicon substrate according to claim 1, wherein the silicon substrate is heat-treated to generate an oxygen precipitate in the silicon substrate, and the silicon substrate after the heat treatment is formed. The method for evaluating a silicon substrate, wherein the silicon substrate is determined to be non-defective when the half width of the infrared absorption peak is 2.1 cm ^-1 or more. 5. A method for preparing a plurality of p-type silicon substrates, extracting one silicon substrate from the plurality of silicon substrates, introducing lithium into the one silicon substrate, and converting oxygen into the one silicon substrate into oxygen. The gettering ability of the one silicon substrate was evaluated by binding lithium and measuring the half width of an infrared absorption spectrum corresponding to the bond between the oxygen and the lithium. A method for manufacturing a semiconductor device, comprising forming a semiconductor element on another silicon substrate by using another silicon substrate other than the silicon substrate.