JPH09229856A - Measuring method for amount of crystal defect, measuring method for injecting amount of ion, and measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quantitatively measure the distribution of crystal defects in a depth direction and the injection amount of ions with high reliability in a noncontact, nondestructive manner. SOLUTION: An invading depth of an entering light to a standard sample which has optical characteristics approximate to a sample is calculated. The depth is divided into a first layer through M-th layer (S2, S3). Refractive index n1, absorption coefficient k1 and depth d1 of the first layer are calculated from a measuring value of a reflecting light of the first layer according to the Fresnel's formula (S5). Thereafter, the second to M-th layers are calculated sequentially. That is, a refractive index nm, an absorption coefficient km and a depth dm of an (m) layer are calculated from the measuring value of the reflecting light resulting from the (m) layer with influences of preceding layers up to the (m) layer taken into consideration (S8, S9, S12). Attenuation rations k1-km are calculated from the refractive indexes n1 to nm and absorption coefficients k1 to km (S6, S10). Crystal defect amounts D1 to Dm of the respective layers are then calculated (S7, S11). In this manner, a depthwise distribution of crystal defect amounts from the first to M-th layers of the sample is measured, and the injection amount of ions is measured from total of the attenuation ratios.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal defect amount measuring method, an ion implantation amount measuring method, and a measuring apparatus, and more particularly to a crystal defect amount capable of measuring the distribution amount of the crystal defect amount in the depth direction. The present invention relates to a method and a measuring device for measuring an ion implantation amount.

[0002]

2. Description of the Related Art Processes for manufacturing semiconductors such as VLSI include processes such as ion implantation into a silicon wafer and plasma etching. In these processes, a crystal defect occurs in a silicon crystal due to ion implantation or the like. .

Nowadays, along with high integration and miniaturization of semiconductor devices and large diameter of wafers, control of crystal defects generated in the above process has become an important issue. Measurement of ion implantation dose,
And the evaluation is an important factor for improving the semiconductor manufacturing efficiency in the semiconductor manufacturing process.

Therefore, during the semiconductor manufacturing process,
As shown in FIG. 4, the crystal defect amount measuring device 10 is arranged on the downstream side of the ion implantation device 50 (or plasma etching device) in the wafer processing process 60 to measure the crystal defect amount and the ion implantation amount, Ion implantation and plasma etching control 70 are performed based on the measured values.

Conventionally, as a measuring device for the amount of crystal defects, a thermal wave method or an acoustic change measuring method has been used.

[0006]

However, the measurement of the amount of crystal defects by the method of measuring the amount of crystal defects by the above-mentioned thermal wave method and the method of measuring the amount of crystal defects by the acoustic change measurement method is performed at the measuring point of the amount of crystal defects. It is a measure of the total amount, and its measured value is not quantitative and is not a universal measurement of physical quantity, so it is affected by the ion species to be injected and the amount of ion injection, and measurement reliability is lacking. There are cases.

The distribution of crystal defects in the depth direction can be measured only by a destructive inspection such as Rutherford backscattering, and can be performed only on a monitor wafer for measurement which is not an actual device.

Therefore, there is a demand for highly reliable, non-contact, non-destructive measurement of the distribution of crystal defects and the amount of ion implantation in the depth direction of an actual device.

Therefore, the present invention has a high reliability, a non-contact, non-destructive, and quantitative method for quantitatively measuring the distribution of crystal defects in the depth direction. It is an object to provide a method and a measuring device.

[0010]

In the present invention, a method of measuring the amount of crystal defects for solving the above-mentioned problems is as shown in FIG. 1, in which light is incident on a sample and the state of reflected light is measured. A method of measuring the crystal defect amount of the sample from the measured amount, in which the penetration depth of incident light into the basic sample having optical characteristics similar to those of the sample is calculated, and the first layer to the M-th layer are calculated. It is divided into M layers (M: an integer of 3 or more) (S2, S3), and the refractive index n1, the absorption coefficient k1, and the thickness d1 of the first layer are calculated from Fresnel's formula based on the measurement amount of the reflected light caused by the first layer. Calculated from (S
5) From the second layer to the Mth layer, from the second layer, from the measured amount of reflected light caused by the mth layer (m: an integer of 2 or more and M or less), the refractive index nm of the mth layer and absorption The coefficient km and the thickness dm are calculated by inserting the influence up to the previous layer (S8, S9, S1).
2) From the calculated refractive index n1 and absorption coefficient k1, the attenuation rate κ
1 is calculated, and the crystal defect amount D of the first layer is calculated from this attenuation rate κ1.
1 is calculated (S6, S7), and the calculated refractive index n
The attenuation rate κm is calculated from m and the absorption coefficient km, and the crystal defect amount Dm of the m-th layer is calculated from this attenuation rate κm (S10,
S11), the crystal defect amount D of the samples from the first layer to the Mth layer
1 to DM are sequentially calculated, and the depth distribution of the crystal defect amount from the first layer to the Mth layer of the sample is measured, which is a method of measuring the crystal defect amount of the sample.

The method of measuring the amount of crystal defects of the present invention is
A method of injecting light into a sample, measuring the state of reflected light, and measuring the amount of crystal defects in the sample from this measured amount, measuring the reflected light spectrum at the measurement point of the sample (S1), and optically measuring the sample. The depth of penetration of the incident light into the sample in each wavelength region is calculated from the basic reflected light spectrum of the basic sample having similar characteristics (S2), and the penetration depth of the incident light is calculated from the first layer to the Mth layer. Divide into layers (M: integer of 3 or more) (S3), first
From the reflection spectrum from the layer, the refractive index n1, the absorption coefficient k1, and the thickness d1 of the first layer were calculated from the Fresnel formula (S
4, S5), from the second layer to the M-th layer, sequentially from the second layer,
From the reflection spectrum from the m-th layer (m: an integer of 2 or more and M or less), the refractive index nm, the absorption coefficient km, and the thickness dm of the m-th layer were calculated from the Fresnel's formula by folding in the influences up to the previous layer. (S8, S9, S12), the attenuation rate κ1 is calculated from the obtained refractive index n1 and absorption coefficient k1, and the attenuation rate κ1 is calculated.
The crystal defect amount D1 of the first layer is calculated from (S6, S7),
Further, from the obtained refractive index nm and absorption coefficient km, the attenuation rate κ
m is calculated, and the crystal defect amount D of the m-th layer is calculated from this attenuation rate κm.
m (S10, S11), the crystal defect amounts D1 to DM of the samples from the first layer to the Mth layer are sequentially calculated, and the depth of the crystal defect amount from the first layer to the Mth layer of the sample is calculated. There is a method for measuring the amount of crystal defects in the sample whose distribution is measured.

Further, the amount of reflected light measured by the method for measuring the amount of crystal defects of the present invention is assumed to be a change in the polarization state of the reflected light measured while changing the incident angle of the incident light on the sample. You can

According to the method of measuring the amount of crystal defects of the present invention, the measured amount of reflected light is P-polarized for incident light of a single wavelength with an incident angle of 0 to sin ^-1 NA which is incident from a lens with a numerical aperture NA. It may be S-polarized and the amount of total reflection.

Further, as shown in FIG. 2, the measuring apparatus for measuring the amount of crystal defects of the present invention makes light incident on the sample 1 and measures the state of reflected light, and based on this measured amount, the crystal defects of the sample. A device for measuring the amount, wherein the depth of penetration of incident light into a basic sample having optical characteristics similar to those of the sample is calculated, and M layers from the first layer to the Mth layer (M: an integer of 3 or more) From the second layer, the first layer refractive index calculation unit 4 that calculates the refractive index n1, the absorption coefficient k1, and the thickness d1 of the first layer from the measurement amount caused by the first layer. From the second layer to the M-th layer in order, the refractive index nm, the absorption coefficient km, and the thickness dm of the m-th layer are calculated from the measurement amount caused by the m-th layer (m: an integer of 2 or more and M or less). The next layer refractive index calculating means 5 for calculating the influences up to and the calculated refractive index n1 and absorption coefficient k1 calculate the attenuation rate κ1. Calculates the crystal defects amount D1 of the first layer from the attenuation rate .kappa.1, further refractive index nm was determined,
The attenuation rate κm is calculated from the absorption coefficient km, and this attenuation rate κ
Defect amount calculating means 6 for calculating the crystal defect amount Dm of the m-th layer from m, and control means for controlling the above-mentioned means to sequentially calculate the crystal defect amounts D1 to DM of the samples from the first layer to the M-th layer. 7 is an apparatus for measuring the amount of crystal defects of a sample, which sequentially calculates the amount of crystal defects D1 to DM of the samples from the first layer to the Mth layer.

The crystal defect amount measuring apparatus of the present invention is
A crystal defect amount measuring device 10 for measuring a crystal defect amount of a sample by injecting a light beam in a predetermined wavelength region into a measurement position of the sample 1 and measuring reflected light, the optical characteristic of which is similar to that of the sample 1). Depth calculation means 2 for calculating the penetration depth of the incident light into the sample in each wavelength range from the reflected light spectrum of the basic sample, and the penetration depth of the incident light from the first layer to the M-th layer (M: integer greater than or equal to 3), and a first layer for calculating the refractive index n1, the absorption coefficient k1, and the thickness d1 of the first layer from the reflection spectrum from the first layer from the Fresnel's formula. The refractive index calculating means 4) and the second to Mth layers are second
From the reflection spectrum from the m-th layer (m: an integer of 2 or more and M or less) sequentially from the layer, the refractive index nm and the absorption coefficient k of the m-th layer
m and the thickness dm are calculated from the Fresnel's formula by folding in the influences up to the front layer, and the attenuation coefficient κ1 is calculated from the calculated refractive index n1 and absorption coefficient k1. The crystal defect amount D1 of the first layer was calculated from κ1, and the attenuation rate κm was calculated from the calculated refractive index nm and absorption coefficient km.
Is calculated, and the crystal defect amount Dm of the m-th layer is calculated from this attenuation rate κm.
And a crystal defect amount calculating means 6 for calculating the crystal defect amounts D1 to D of the samples from the first layer to the Mth layer by controlling the respective means.
A device for measuring the amount of crystal defects of a sample, which comprises a control unit 7 for sequentially calculating M and measures the depth distribution of the amount of crystal defects from the first layer to the M-th layer of the sample.

Further, in the crystal defect amount measuring device of the present invention, a spectroscope 8 for measuring the reflection spectrum from the ultraviolet region to the visible region can be provided.

In the crystal defect amount measuring device of the present invention, the measurement amount of the reflected light can be a change in the polarization state of the reflected light measured while changing the incident angle of the incident light on the sample.

Further, in the crystal defect amount measuring device of the present invention, the measured amount of the reflected light is the incident light of a single wavelength with an incident angle of 0 ° to (sin ^-1 NA) ° which is incident from a lens having a numerical aperture NA. Can be P-polarized light, S-polarized light, and total reflection amount.

Furthermore, the ion implantation amount measuring method of the present invention is a method of measuring the ion implantation amount into the sample from the measured amount by injecting light into the sample, measuring the state of reflected light, The penetration depth of the incident light into the basic sample, which has optical characteristics similar to those of the sample, is calculated and divided into M layers (M: an integer of 3 or more) from the first layer to the Mth layer, which results from the first layer. From the measured amount of reflected light, the refractive index n1, the absorption coefficient k1, and the thickness d1 of the first layer are calculated from the Fresnel formula, and the second layer to the Mth layer are sequentially arranged from the second layer to the mth layer (m : An integer of 2 or more and M or less) from the measured amount of reflected light to the refractive index n of the m-th layer
m, the absorption coefficient km, and the thickness dm are calculated by inserting the influence up to the previous layer, and the attenuation rate κ1 is calculated from the calculated refractive index n1 and absorption coefficient k1, and the calculated refractive index nm and absorption coefficient km are calculated. Then, the attenuation rate κm is calculated, the values of the attenuation rate κ1 to the attenuation rate κm are added, and the amount of ion implantation into the crystal is measured from this value.

The ion implantation dose measuring device of the present invention is a device for injecting light into a sample, measuring the state of reflected light, and measuring the ion implantation dose into the sample based on this measured amount. Dividing operation means for calculating the penetration depth of incident light into a basic sample having optical characteristics similar to those of the sample and dividing the depth into M layers (M: an integer of 3 or more) from the first layer to the Mth layer, First
The first layer refractive index calculating means for calculating the refractive index n1, the absorption coefficient k1, and the thickness d1 of the first layer from the measurement amounts caused by the layers, and the second layer to the Mth layer from the second layer in order. Refractive index of the next layer calculated from the measurement amount caused by the m-th layer (m: an integer of 2 or more and M or less) by calculating the refractive index nm, the absorption coefficient km, and the thickness dm of the m-th layer by folding in the influences up to the previous layer. An attenuation rate κ1 is calculated from the calculating means and the calculated refractive index n1 and the absorption coefficient k1, and an attenuation rate κm is calculated from the calculated refractive index nm and the absorption coefficient km, and the attenuation rates κ1 to κm are calculated. And an ion implantation both-calculating means for measuring the ion implantation amount into the crystal from this value are added, and the ion implantation amount into the sample is calculated.

Therefore, according to the method for measuring the amount of crystal defects, the method for measuring the amount of ion implantation, and the measuring apparatus according to the present invention, the crystal defects of the sample are determined based on the amount of the crystal defects up to a predetermined depth of the sample. Since the amount is measured and the attenuation rate κ which is an optical constant is determined based on the measured amount, it is possible to perform a quantitative measurement independent of the ion implantation amount and the ion species.

Further, according to the present invention, the penetration depth of incident light is calculated, the sample is divided into M layers (M: an integer of 3 or more) from the first layer to the Mth layer, and the measurement result is obtained. On the basis of,
From the first layer to the M-th layer, the refractive index, the absorption coefficient, and the thickness are sequentially calculated by inserting the influences up to the previous layer, and the attenuation rate κ is calculated from this, and the crystal defect amount D1 of the sample is calculated from the attenuation rate κ. ~
Since DM is sequentially calculated, the depth distribution of the amount of crystal defects from the first layer to the Mth layer of the sample can be measured. Then, the ion implantation amount to the sample is calculated by summing the above attenuation rates κ1 to κm, and as shown in FIG. 16, the ion implantation amount is obtained from the relationship between the total attenuation rate and the ion implantation amount which is obtained in advance. You can

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION A crystal defect amount measuring method, an ion implantation amount measuring method, and a measuring apparatus according to embodiments of the present invention will be described in detail below.

[Description of First Embodiment] First, an apparatus that operates by the crystal defect amount measuring method according to this embodiment will be described. In this example, during the semiconductor manufacturing process shown in the conventional example, as shown in FIG. 4, the crystal defect amount measuring device 10 is arranged on the downstream side of the ion implantation device 50 or the plasma etching device, and the crystal defect amount is increased. Is measured
Ion implantation and plasma etching are controlled based on the measured values.

In this control, the amount of crystal defects is measured to confirm whether the set ion implantation is normally performed, the abnormality of the ion implantation apparatus is confirmed, or the ion implantation amount is insufficient. In this case, the silicon wafer is again ion-implanted.

The crystal defect amount measuring apparatus is equipped with a spectroscope 8 for detecting the reflected light spectrum.

In the crystal defect amount measuring apparatus 10 according to the present example, as shown in FIG. 2, from the reflected light spectrum of the basic sample having uniform optical characteristics similar to those of the sample 1,
Depth calculation means 2 for calculating the penetration depth of the incident light into the sample in each wavelength region, and division calculation means 3 for dividing the penetration depth of the incident light into three layers from the first layer to the Mth layer. The first layer refractive index calculating means 4 for calculating the refractive index n1, the absorption coefficient k1, and the thickness d1 of the first layer from the reflection spectrum from the first layer, and the second layer and the third layer are calculated as the first layer. The refractive index of the m-th layer n
Next layer refractive index calculating means 5 for calculating m, absorption coefficient km, and thickness dm from the Fresnel's formula by folding in the influence up to the previous layer.
From the obtained refractive index n1 and absorption coefficient k1, the attenuation rate κ1
From the attenuation factor κ1 and the crystal defect amount D1 of the first layer
And the calculated refractive index n2, n3, absorption coefficient k
1, k2, the attenuation rate κ2, k3 is calculated, and the crystal defect amount D2, D3 of the m-th layer is calculated from the attenuation rate κ2, k3. 1
And a control unit 7 for sequentially calculating the crystal defect amounts D1 to D3 of the samples from the layers to the Mth layer.

In this example, the depth calculating means 2,
The division calculation means 3, the first layer refractive index calculation means 4, the next layer refractive index calculation means 5, the crystal defect amount calculation means 6 and the control means 7 are
Specifically, the CPU of the computer realizes each functional unit by executing a given program. The device may be configured by providing dedicated hardware as these means.

The reflection spectrum spectroscope 8 for detecting the reflection light spectrum is used for ordinary film pressure measurement. As shown in FIG. 3, a light source 21, a condensing optical system 22, and A beam splitter 23, a reference unit 24 for obtaining a reference light signal for noise fluctuation correction of a light source, a diffraction grating 25 for dispersing reflected light from a sample, and a low noise detector 26 for measuring light intensity at each wavelength. Equipped with.

In this example, the light source 21 has a wavelength of 100 nm
A xenon arc lamp (or a combination of a tungsten halogen lamp and a deuterium lamp) having a continuous wavelength in the wavelength range of 1000 nm (from the ultraviolet range to the visible range) is used, and the condensing optical system 22 can be used in the above wavelength range. As the diffraction grating, a fixed type holographic grating having aberration correction capability is used. A CCD array with a temperature control function is used as the low noise detector, and the reflectance in each wavelength region is output.

Next, the operating state of the apparatus according to this example will be described together with the measurement principle of this example. The measurement apparatus for measuring the amount of crystal defects according to this example operates as follows.

First, as shown in FIGS. 1 to 3, the spectroscope 8 makes the luminous flux in the predetermined wavelength region incident on the measurement position of the sample 1 and disperses the reflected light to obtain the reflectance in each wavelength region. measure.

As a result, the spectroscope 8 outputs the relationship between the reflectance and the wavelength as shown in FIG. 9 (S1). FIG. 9 shows an example of measurement of four types of samples.
In this measurement example, p-type (100) Si is used as the substrate,
As + was ion-implanted at an energy of 100 KeV, and the dose was 3 × 10 ¹² ion / cm ² (○).
Mark), 3 × 10 ¹³ ion / cm ² (● mark), 1 × 10 ¹⁵
ion / cm ² (■ mark), and 1 × 10 ¹⁶ ion / cm
² (square mark).

Then, in the present apparatus, the penetration depth of the incident light into each sample in each wavelength region is calculated based on the basic reflected light spectrum of the basic sample having the optical properties similar to those of the sample 1 (S2). . In this case, when ion implantation is performed on a sample silicon wafer, or when ion implantation with low density is performed, single crystal silicon is used as a basic sample, and implantation with high density is performed, and a defect layer with high density is provided. Amorphous silicon is used as a basic sample when it is expected to be a material. In these cases, the penetration depth into both basic samples is in good agreement with the theoretical calculation and the experimental value, so the penetration depth obtained by the theoretical calculation can be used.

FIG. 11 shows each wavelength (30
0, 400, 500, 600, 700 and 800 nm)
FIG. 12 shows the energy density ratio at each depth in amorphous silicon, and FIG. 12 shows the relationship between the penetration depth of light into amorphous silicon and the wavelength. From these, it can be seen that light of long wavelength penetrates deeper than light of short wavelength.

Next, the penetration depth of the incident light is first measured from the surface.
A layer, a second layer, and a third layer are divided into three layers (S3).
It is known that, as shown in FIG. 5, the amount of crystal defects when the silicon substrate is ion-implanted begins to increase from the surface as shown in FIG.
It tends to decrease. Therefore, as shown in FIG. 7, at least three layers (first layer (complex refractive index:
n1 + ik1), the second layer (complex refractive index: n2 + ik)
2) By dividing the third layer (complex refractive index: n3 + ik3)), the distribution of the amount of crystal defects in the depth direction can be measured.

If the surface is appropriately divided into three layers, as shown in FIG. 8, for example, light having a wavelength of 200 nm or less exhibits a spectrum determined by the optical constants of the first layer, and light having a wavelength of 400 nm or less is obtained. A spectrum determined by the optical constants of the first layer and the second layer is shown, and similarly, light having a longer wavelength, for example, a wavelength of 800 nm shows a spectrum determined by the optical constants of the first layer, the second layer, and the third layer. .

In this example, the first layer is 25 nm from the surface,
The second layer is set to 100 nm and the third layer is set to 200 nm, and the wavelength affected by the amount of crystal defects up to the respective layers is a wavelength of 300 nm for a depth of 25 nm,
Data with a wavelength of 400 nm was used for a depth of 100 nm, and data with a wavelength of 300 nm or less was used for a depth of 200 nm. These criteria are in the graph shown in FIG.
An energy density ratio of 50% or more at each depth was selected. This value can be appropriately selected as needed.

Next, from the reflection spectrum from the first layer, the refractive index n1, the absorption coefficient k1, and the thickness d1 of the first layer are calculated from the Fresnel's formula (S4, S5). This calculation is the first
The refractive index n1, the absorption coefficient k1, and the thickness d1 of the layer are appropriately selected, and the Fresnel formula is used.

[0040]

[Equation 1]

Substituting in (1) of (1), the reflectance at each wavelength is calculated, and the spectral curve obtained by the calculation has a distribution that is closest to the spectral curve actually obtained by the measurement (FIG. 9). n, absorption coefficient k, and thickness d are the refractive index n of the first layer.
1, the absorption coefficient k1, and the thickness d1.

At this time, the calculated thickness d1 may be different from the previously determined value of the first layer (for example, 25 nm), which is the optical difference between the basic sample and the sample. Since it is caused by the difference in the constant, the actual spectrum is adopted.

In this example, according to the Fresnel's formula (2), the refractive index n1 and the absorption coefficient k1 are converted to the attenuation rate κ.
1, and the crystal defect amount D1 of the first layer is calculated from the known relationship between the attenuation factor κ and the crystal defect amount D (S).
7). There is a fixed relationship between the attenuation rate κ and the crystal defect amount D, which can be determined and determined experimentally.

The attenuation rate κ and the crystal defect amount D may be calculated collectively after calculating the refractive index and the absorption coefficient of the second layer and the third layer.

Next, the second layer has a refractive index n2 and an absorption coefficient k.
2. The thickness d2 is calculated from the Fresnel formula by folding in the influence of the first layer (S8, S9, S12). This calculation is
Considering the refractive index n1, the absorption coefficient k1, and the thickness d1 calculated for the first layer, the refractive index n2, the absorption coefficient k2, and the thickness d2 of the second layer are appropriately selected, and these values are set to the Fresnel value. Substituting into the formula, the reflectance at each wavelength is calculated, and the combination of each value whose calculated spectral curve is closest to the measured spectral curve is the refractive index n2 of the second layer and absorption. The coefficient k2 and the thickness d2 are determined.

Then, in this example, the refractive index n2, the absorption coefficient k2, and the attenuation rate κ2 are calculated, and the crystal defect amount D2 of the second layer is calculated from the attenuation rate κ2 (S10, S11).
Similarly, with respect to the third layer, the refractive index n1, the absorption coefficient k1, and the thickness d1 calculated for the first layer, and the refractive index n2, the absorption coefficient k2, and the thickness d2 calculated for the second layer are taken into consideration. The crystal defect amount D3 of is calculated (S11).

As a result, the crystal defect amount from the first layer to the third layer of the sample can be measured, and the amount of crystal defect amount D in the depth direction is displayed as shown in FIGS. 13 to 15. S13).

Here, each drawing shows a p-type (10
0) Si is used and As + is 100 KeV as an ion species.
Measurement results of this sample and the TRIM (TRansport of Ion i
n Matter) simulation results are shown. 13 is 3 × 10 ¹⁴ ion / cm ² , and FIG. 14 is 1
× 10 ¹⁵ ion / cm ² , FIG. 15 shows 3 × 10 ¹⁶ ion / cm ²
cm ² is shown.

In each figure, ● indicates the crystal defect amount D (right scale) of the sample obtained by known TRIM simulation, and ○ indicates the attenuation rate κ (left scale) obtained in this example. . It is known that the result obtained by this TRIM simulation is in good agreement with the result obtained by the destructive inspection of the actual amount of crystal defects.

In each of the figures, the tendency of the crystal defect amount of the simulation and that of the attenuation amount obtained in this example are in good agreement, and by performing appropriate correction, the sample of the sample is obtained by the measurement of this example. It can be seen that the distribution of the amount of crystal defects in the silicon wafer in the depth direction can be measured.

As described above, according to the crystal defect amount measuring method and the measuring apparatus according to the present embodiment, the crystal defect amount of the sample is determined based on the amount of the crystal defect up to the predetermined depth of the sample. Is measured, and the attenuation factor κ, which is an optical constant, is determined based on the measured value. Therefore, quantitative measurement that does not depend on the ion implantation amount or ion species can be performed.

Then, according to this example, the penetration depth of the incident light is calculated, the sample is divided into the first layer to the third layer, and the first layer to the third layer are based on the measurement result. , The refractive index, the absorption coefficient, and the thickness are sequentially calculated by inserting the influences up to the previous layer, the attenuation rate κ is calculated from this, and the crystal defect amounts D1 to D3 of the sample are sequentially calculated from the attenuation rate κ. The depth distribution of the amount of crystal defects from the first layer to the third layer of the sample can be measured.

[Description of Other Embodiments] In the above embodiment, the reflectance (reflection spectrum) of each wavelength region of white light is measured as the measurement amount of the reflected light to measure the crystal defect amount of each layer. However, the present invention can be applied without limiting the measurement amount to the reflection spectrum. That is, the polarization state of the reflected light measured while changing the incident angle of the laser incident light of a plurality of wavelengths on the sample by the method using the ellipsometry as a measurement principle (epometry) changes the Fresnel's value from these values. Using the same method as in the above-described embodiment based on the formula, the complex refractive index (nm + ikm) of each layer,
The thickness dm is calculated and the attenuation rate κm is the crystal defect rate Dm of a plurality of layers.
Can be requested.

In this case, the fact that the depth of incidence of light on the sample differs depending on the incident angle and wavelength of the incident light and that the degree of polarization rotation is different depending on the complex refractive index of the sample is utilized. However, the basic idea for obtaining the crystal defect amount D for each layer is the same as in the present invention.

A method similar to this ellipsometry method is used.
As a measurement amount of reflected light, a large numerical aperture NA (for example, 0.
Angle of incidence 0 ° from the microscope objective lens of 9)
(Sin ^-1NA) ° (eg 0 ° to 64 °) single wavelength
P polarization and S polarization of the reflected light with respect to the incident light that is the linearly polarized light of
The profile of light and the amount of total reflection are measured to determine the polarization state.
Based on Fresnel's formula from
The complex refractive index of each layer (nm
+ Ikm) and the thickness dm, and the crystal defect rate D of the multiple layers
m can be obtained.

In this case, the fact that the incident depth of light on the sample differs depending on the incident angle of the incident light and the degree to which the polarized light is rotated depending on the complex refractive index of the sample is utilized. The basic idea is the same as that of the present invention.

[Explanation of Ion Implantation Quantity Measuring Device] It is generally known that there is a certain relationship between the total attenuation κ of crystals and the dose of ions, as shown in FIG. Therefore, the above-described crystal defect amount measuring device is provided with an adding means for adding the attenuation amounts κ1 to κm in each layer, and the relationship shown in FIG. 16 is applied based on the total attenuation rate κ obtained by the adding means. The ion implantation amount of the sample can be measured by providing the ion implantation amount calculation device. This can be realized by changing a part of the program of the computer that constitutes the above-mentioned crystal defect amount measuring device.

In each of the above-mentioned embodiments, the method of measuring the reflected light of the crystal by using the reflectance according to the wavelength, the change of the polarization of the reflected light, and the numerical aperture of the lens of the incident light has been described. Any measured amount can be adopted as long as it changes due to crystal defects up to a predetermined depth of the sample.

The crystal defect amount measuring method, the ion implantation amount measuring method, and the measuring device according to the present invention are arranged on the downstream side of the ion implantation device 50 or the plasma etching device. The amount of crystal defects can be measured, and ion implantation and plasma etching can be controlled based on the measured value. This management checks the amount of crystal defects and the amount of ion implantation to check whether the set ion implantation is normally performed, confirms that the ion implantation system is abnormal, or that the amount of ion implantation is insufficient. In such a case, ion implantation or the like may be performed again on the silicon wafer, or such measurement may be performed during ion implantation or plasma etching to automatically control ion implantation or plasma etching.

[0060]

As described above, according to the method for measuring the amount of crystal defects, the method for measuring the amount of ion implantation, and the measuring apparatus according to the present invention, the amount of crystal defects due to the crystal defects up to a predetermined depth of the sample can be determined. The amount of crystal defects in the sample is measured based on this, and the attenuation factor κ, which is the optical constant, is determined based on this, so the effect of being able to perform quantitative measurement that does not depend on the ion implantation amount or ion species is obtained. Play.

Further, according to the present invention, the penetration depth of the incident light is calculated, the sample is divided into M layers from the first layer to the Mth layer, and the first layer to the Mth layer are determined based on the measurement result. Up to the M layer, the refractive index, the absorption coefficient, and the thickness are sequentially calculated by inserting the influences up to the previous layer, the attenuation rate κ is calculated, and the crystal defect amounts D1 to DM of the sample are sequentially calculated from the attenuation rate κ. Therefore, it is possible to measure the depth distribution of the crystal defect amount from the first layer to the M-th layer of the sample and the ion implantation amount.

[Brief description of drawings]

FIG. 1 is a flowchart showing an embodiment of a crystal defect amount measuring method according to the present invention.

FIG. 2 is a block diagram showing an embodiment of a crystal defect amount measuring device according to the present invention.

3 is a diagram showing an optical system of a spectroscope of the crystal defect amount measuring device shown in FIG.

FIG. 4 is a diagram showing an arrangement position of a crystal defect amount measuring device according to the present invention during a semiconductor manufacturing process.

FIG. 5 is a schematic cross-sectional view showing a state of ion implantation into a silicon substrate.

FIG. 6 is a graph showing the relationship between the depth of an ion-implanted sample and the amount of crystal defects.

FIG. 7 is a schematic cross-sectional view showing the distribution state of the complex refractive index of the ion-implanted sample.

FIG. 8 is a schematic cross-sectional view showing how light enters a sample.

FIG. 9 is a graph showing an example of a reflection spectrum of a sample.

FIG. 10 is a graph showing the relationship between sample depth and attenuation rate.

FIG. 11 is a graph showing the depth of an amorphous silicon sample and the energy density ratio of light.

FIG. 12 is a graph showing a penetration depth depending on a wavelength into amorphous silicon.

FIG. 13 is a graph showing the relationship between the depth and the attenuation rate and the amount of crystal defects for evaluation of measurement.

FIG. 14 is a graph showing the relationship between the depth and the attenuation rate and the amount of crystal defects for evaluation of measurement.

FIG. 15 is a graph showing the relationship between the depth and the attenuation rate and the amount of crystal defects for evaluating the measurement.

FIG. 16 is a graph showing the relationship between the total attenuation rate κ and the ion implantation amount (dose amount).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 sample 2 depth calculating means 3 division calculating means 4 first layer refractive index calculating means 5 next layer refractive index calculating means 6 crystal defect amount calculating means 7 control means 8 spectroscope 10 crystal defect measuring device

Claims (11)

[Claims] 1. A method for injecting light into a sample, measuring the state of reflected light, and measuring the amount of crystal defects in the sample from this measured amount, which is incident on a basic sample having optical characteristics similar to those of the sample. The penetration depth of light is calculated and divided into M layers (M: an integer of 3 or more) from the first layer to the Mth layer (S2, S3), and the measured amount of reflected light caused by the first layer is calculated. Refractive index n of the first layer
1, the absorption coefficient k1 and the thickness d1 were calculated from the Fresnel formula (S5), and the second layer to the Mth layer were sequentially arranged from the second layer to the mth layer (m:
From the measured amount of reflected light due to (integer of 2 or more and M or less), the refractive index nm, the absorption coefficient km, and the thickness dm of the m-th layer are calculated by folding in the influences up to the previous layer (S8, S9, S12). From the calculated refractive index n1 and absorption coefficient k1, the attenuation rate κ1 is calculated, and the crystal defect amount D1 of the first layer is calculated from this attenuation rate κ1 (S6, S7). The attenuation rate κm is calculated from the coefficient km, and the crystal defect amount Dm of the m-th layer is calculated from this attenuation rate κm (S10, S1).
1), the crystal of the sample from which the crystal defect amounts D1 to DM of the samples from the first layer to the M-th layer are sequentially calculated to measure the depth distribution of the crystal defect amount from the first layer to the M-th layer of the sample Defect amount measurement method. 2. A method of injecting light into a sample, measuring the state of reflected light, and measuring the amount of crystal defects in the sample from this measured amount, wherein the reflected light spectrum at the measurement point of the sample is measured (S1). ), The penetration depth of the incident light into the sample in each wavelength region is calculated from the basic reflected light spectrum of the basic sample whose optical characteristics are similar to those of the sample (S2), and the penetration depth of the incident light is calculated from the first layer to the first layer. M layers up to M layer (M:
(Integer of 3 or more) (S3), and from the reflection spectrum from the first layer, the refractive index n1 of the first layer,
The absorption coefficient k1 and the thickness d1 are calculated from the Fresnel's formula (S4, S5), and the second layer to the Mth layer are sequentially arranged from the second layer to the mth layer (m: an integer of 2 or more and M or less). The refractive index nm, the absorption coefficient km, and the thickness dm of the m-th layer are calculated from the reflection spectrum from (3) using the Fresnel formula (S
8, S9, S12), the attenuation rate κ1 is calculated from the obtained refractive index n1 and absorption coefficient k1, and the crystal defect amount D1 of the first layer is calculated from this attenuation rate κ1 (S6, S7), and also calculated. The attenuation rate κm is calculated from the refractive index nm and the absorption coefficient km, and the crystal defect amount Dm of the m-th layer is calculated from this attenuation rate κm (S10, S11). A method of measuring the amount of crystal defects in a sample, which sequentially calculates the amount of crystal defects D1 to DM and measures the depth distribution of the amount of crystal defects from the first layer to the M-th layer of the sample. 3. The method for measuring a crystal defect amount according to claim 1, wherein the measurement amount of the reflected light is a change in the polarization state of the reflected light measured while changing the incident angle of the incident light on the sample. 4. The measured amount of the reflected light is P-polarized light, S-polarized light and total reflection amount with respect to incident light of a single wavelength having an incident angle of 0 to sin ⁻¹ NA which is incident from a lens having a numerical aperture NA. 1. The method for measuring the amount of crystal defects according to 1. 5. A device for measuring the state of reflected light by injecting light into a sample (1) and measuring the amount of crystal defects in the sample based on the measured amount, which has a basic optical property similar to that of the sample. A division calculation means (3) for calculating the penetration depth of the incident light to the sample and dividing it into M layers (M: an integer of 3 or more) from the first layer to the Mth layer, and the division calculation means (3). The first layer refractive index calculating means (4) for calculating the refractive index n1, the absorption coefficient k1, and the thickness d1 of the first layer from the measured amount, and the second layer to the Mth layer from the second layer in order. Next layer refractive index calculation that calculates the refractive index nm, absorption coefficient km, and thickness dm of the mth layer from the measurement amount caused by the m layer (m: an integer of 2 or more and M or less) by folding in the influence on the previous layer Means (5)
Then, the attenuation rate κ1 is calculated from the obtained refractive index n1 and the absorption coefficient k1, the crystal defect amount D1 of the first layer is calculated from this attenuation rate κ1, and further, from the obtained refractive index nm and the absorption coefficient km,
Defect amount calculating means (6) for calculating the attenuation rate κm and calculating the crystal defect amount Dm of the m-th layer from the attenuation rate κm, and the above-mentioned means for controlling each of the samples from the first layer to the M-th layer A control device (7) for sequentially calculating the crystal defect amounts D1 to DM, and a device for measuring the crystal defect amount of the samples, which sequentially calculates the crystal defect amounts D1 to DM of the samples from the first layer to the Mth layer. 6. A crystal defect amount measuring device (10) for measuring a crystal defect amount of a sample by injecting a light beam in a predetermined wavelength region into a measurement position of the sample (1) and measuring reflected light. Depth calculation means (2) for calculating the penetration depth of the incident light into the sample in each wavelength region from the reflected light spectrum of the basic sample having optical characteristics similar to those of the sample (1), and the penetration depth of the incident light From the first layer to the Mth layer (M:
A division calculation unit (3) for dividing the first layer into a refractive index n1 of the first layer,
The first layer refractive index calculating means (4) for calculating the absorption coefficient k1 and the thickness d1 from the Fresnel's formula, and the second to Mth layers from the second layer to the mth layer (m:
From the reflection spectrum from 2 or more and M or less)
From the next layer refractive index calculation means (5) for calculating the refractive index nm, the absorption coefficient km, and the thickness dm of the layer from the Fresnel's formula by incorporating the influence up to the previous layer, and the calculated refractive index n1 and absorption coefficient k1, The attenuation rate κ1 is calculated, the crystal defect amount D1 of the first layer is calculated from this attenuation rate κ1, the attenuation rate κm is calculated from the obtained refractive index nm and the absorption coefficient km, and this attenuation rate κm is calculated as A crystal defect amount calculating means (6) for calculating the crystal defect amount Dm of the m layer, and a control means for controlling the respective means to sequentially calculate the crystal defect amounts D1 to DM of the samples from the first layer to the Mth layer. (7) An apparatus for measuring a crystal defect amount of a sample, comprising: (1) measuring the depth distribution of the crystal defect amount from the first layer to the Mth layer of the sample. 7. The crystal defect amount measuring device according to claim 6, further comprising a spectroscope (8) for measuring a reflection spectrum from an ultraviolet region to a visible region. 8. The crystal defect amount measuring device according to claim 5, wherein the measurement amount of the reflected light is a change in the polarization state of the reflected light measured while changing the incident angle of the incident light on the sample. 9. The measurement amount of the reflected light is P-polarized light, S-polarized light and total reflection amount with respect to a single wavelength incident light having an incident angle of 0 ° to (sin ⁻¹ NA) °, which is incident from a lens having a numerical aperture NA. 6. The apparatus for measuring the amount of crystal defects according to claim 5. 10. A method for measuring a state of reflected light by injecting light into a sample, and measuring an amount of ion implantation into the sample from the measured amount, which comprises: The penetration depth of the incident light is calculated and divided into M layers (M: an integer of 3 or more) from the first layer to the Mth layer, and the first layer is calculated from the measured amount of the reflected light caused by the first layer. Refractive index n
1, the absorption coefficient k1 and the thickness d1 were calculated from the Fresnel's formula, and from the second layer to the M-th layer, from the second layer to the m-th layer (m:
(Integer of 2 or more and M or less), the refractive index nm, the absorption coefficient km, and the thickness dm of the m-th layer are calculated by folding in the influences up to the previous layer from the measured amount of reflected light, and the obtained refractive index n1, From the absorption coefficient k1, the extinction coefficient κ1 is calculated, and from the obtained refractive index nm and absorption coefficient km,
A method for measuring the amount of ion implantation into a sample in which the attenuation rate κm is calculated, the values of the attenuation rate κ1 to the attenuation rate κm are added together, and the amount of ion implantation into the crystal is measured from this value. 11. A device for injecting light into a sample, measuring the state of reflected light, and measuring the amount of ion implantation into the sample based on the measured amount, wherein the sample is a basic sample having optical characteristics similar to those of the sample. Of the incident light is calculated and divided into M layers (M: an integer of 3 or more) from the first layer to the Mth layer, and a first amount is calculated from the measurement amount caused by the first layer. The first layer refractive index calculating means for calculating the refractive index n1, the absorption coefficient k1, and the thickness d1 of the layer, and the second layer to the Mth layer from the second layer sequentially from the mth layer (m: 2 or more, Next layer refractive index calculating means for calculating the refractive index nm, the absorption coefficient km, and the thickness dm of the m-th layer from the measurement amount caused by (the integer less than or equal to M), and calculating the calculated refractive index n1. , The attenuation coefficient κ1 is calculated from the absorption coefficient k1, and the calculated refractive index nm and the absorption coefficient km are
The attenuation rate κm is calculated, the values of the attenuation rate κ1 to the attenuation rate κm are added together, and an ion implantation both-calculation means for measuring the ion implantation amount into the crystal from this value is provided, and the ion implantation amount into the sample is calculated. Device for measuring the amount of ion implantation into a sample.