JPH05264468A - Method and apparatus for detecting internal - Google Patents

Abstract

PURPOSE:To detect an internal defect by casting a first and a second lights of the wavelength generating a relatively large amount of light data of the surface and the interior of an object into the object, and comparing the obtained light data with each other. CONSTITUTION:A visual field 203 of a TV camera observation system 201 is sectioned into detecting areas 1a-4a corresponding to the depth of layers 1b-4b of a to-be-detected object 105. A focal position is made corresponding to the depthwise position of the boundary between the layers 2b and 3b, and then the position of a laser beam 101 is adjusted so that a focused point 205 of the laser beam 101 comes to a position corresponding to the detecting area 1a, 2a, 3a, 4a as a target detecting layer. Accordingly, the detecting areas 1a-4a in the visual field 203 correspond to the layers 1b-4b. A first and a second lights of the wavelength generating a relatively large amount of light data on the surface and the interior of the object 105 are guided into the object 105, and the obtained light data for every incident light is compared, whereby an internal defect of the object is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for illuminating an internal defect of an object to be inspected such as a semiconductor wafer having a multi-layer structure by using laser light or the like and observing scattered light or the like. ..

[0002]

2. Description of the Related Art Conventionally, as a method of observing defects in each layer of a semiconductor wafer having a multi-layer structure of Si crystal, a laser beam having a wavelength of 1800 nm is irradiated on the wafer with its beam diameter expanded to scatter the scattered light. To observe (T. Ogawa,
Lu Taijing and K. Toyoda, Jpn. J. Appl. Phys. 30 (1
991) L1393), a method of irradiating a fixed wavelength laser such as an Ar laser on a wafer and observing the reflected light (EF Steigmei
er and H. Auderset, Applied Physics A, (1990) 531)
Etc. are known.

In addition, Japanese Patent Application Laid-Open No. 4-
In No. 24541, it is known that a scattering image of a specific depth from the wafer surface is obtained by changing the wavelength of the incident laser to change the penetration depth into the wafer.

On the other hand, in the automatic focusing mechanism in the microscope used for observing such defects, a method of irradiating the wafer with laser light from the microscope side and observing the reflected light is used. Also known is a method of focusing by projecting a specific pattern and observing the image.

However, in the method using the fixed wavelength laser, there is a problem that it is not possible to determine whether the defect exists on the surface or inside. Also,
In the method described in JP-A-4-24541, when the resolution in the depth direction is 4 to 5 μm and the layer thickness is several thousand Å, which is about the wavelength of the laser beam, in the multilayer structure of Si crystal, The resolution is too low to identify again whether the defect is on the surface or inside.

Further, in the focusing method for observing the reflected light, there is a problem that the focusing cannot be performed unless the inclination of the wafer normal to the laser optical axis is within about ± 5 °. Further, in the focusing method for observing the projected image, a special mechanism is required to apply this to a sample that is positively tilted. In other words, if the pattern is projected onto a place where it is desired to be observed, the pattern interferes with the subsequent measurement after focusing, so that a countermeasure is required.

In view of the above problems of the prior art, the present invention detects internal defects in a multi-layer semiconductor substrate such as a semiconductor wafer having a multi-layer structure and identifies the position and depth of each layer in which the defect exists. To be able to detect.

[0008]

In order to achieve the above object, according to the present invention, predetermined light is made incident on an object to be inspected, and optical information from the object to be inspected thereby is obtained and obtained through an observation optical system. In the method of detecting an internal defect of an object to be inspected based on the obtained optical information, the first light having a wavelength that generates a relatively large amount of optical information on the surface of the object to be inspected and the optical information inside the object to be inspected The second light having a wavelength that is generated relatively often is made incident on the object to be inspected, the optical information generated by each incident light is obtained, and the internal information is detected by comparing the both optical information. ing.

The optical information may be scattered light, fluorescent light, or specularly reflected light, but scattered light to be obtained as optical information can be obtained by appropriately selecting the wavelengths of the first and second incident lights. It is preferable to obtain the optical information by not selecting the scattering direction of the light with the spatial filter so as not to be influenced by the diffracted light due to the fine structure of the surface of the object to be inspected.

If the beam diameters of the incident surfaces of the first and second incident lights are about the same as the field of view of the observation optical system, it is not necessary to two-dimensionally scan the object to be inspected.

When the object to be inspected is a wafer having a multi-layer structure of Si crystals, the wavelengths of the first incident light and the second incident light are both within the range of 400 to 2000 nm, or the first incident light is within the range of 400 to 2000 nm. The wavelength of incident light is preferably in the range of 200 to 650 nm. In addition, the first incident light has a wavelength of 400 to
The laser light of 1330 nm may be used, the second incident light may be its second harmonic, and the fundamental wave and the second harmonic may be simultaneously incident on the object to be inspected, or the first incident light and the second harmonic The incident light may be separately emitted from the wavelength tunable laser device.

In another aspect of the present invention, a laser beam is made to enter the object to be inspected, and a scattered image due to the scattered light from the object to be inspected thereby is obtained through a microscope. In the method of detecting an internal defect, an incident laser beam is made to have its refracted light in a test object have a predetermined small cross section, and a scattered image generated by the refracted light is used as an optical axis of the refracted light. The depth position in the object to be inspected of the defect image obtained by the microscope on an optical axis that intersects at a predetermined angle and substantially intersects the position in the field of view of the microscope in which the defect image exists. It is characterized in that the object to be inspected is two-dimensionally scanned with the incident laser beam.

In this case, for example, the normal to the surface of the object to be inspected forms an angle of 5 to 35 ° with respect to the optical axis of the microscope, and a predetermined pattern is imaged on the focal plane of the microscope. The distance between the microscope and the object to be inspected is adjusted based on the projected image of this pattern.

In still another embodiment, predetermined light is incident on the object to be inspected, optical information from the object to be inspected thereby is obtained through an observation optical system, and the object to be inspected is obtained based on the obtained optical information. In the method of detecting the internal defect of the object, the normal line of the object surface to be inspected makes an angle with respect to the optical axis of the observation optical system, and when focusing the observation optical system, a predetermined plane is set on the focal plane of the microscope. It is characterized in that a pattern is formed and the distance between the microscope and the object to be inspected is adjusted based on the projected image of this pattern on the surface of the object to be inspected.

In any of the aspects, the obtained optical information is usually converted into image data by photoelectric conversion.

[0016]

When the first and second light beams having wavelengths that generate relatively large amounts of light information on the surface and inside of the object to be inspected are incident on the object to be inspected, the scattered light caused by the first light is not reflected. The optical information from the defect existing on the surface of the inspection object is included more than the optical information from the defect existing on the inside of the inspection object, and the scattered light caused by the second light has the defect existing inside the inspection object. The optical information from the optical disk is included more than the optical information from the defect existing on the surface of the object to be inspected. Thus, for each incident light, the optical information generated thereby is obtained and both optical information are compared, for example by removing the optical information obtained by the first light from the optical information obtained by the second light. , Only the defects that are truly inside are detected.

In another aspect of the present invention, when the incident laser beam is incident on the object to be inspected, the refracted light in the object to be inspected has a predetermined small cross section, and therefore the refracted light illuminates the object to be inspected. The area inside the object is a linear area or a planar area along the optical axis. Therefore, when observing this region with the microscope on the optical axis that intersects the optical axis of the refracted light at a predetermined angle, the depth of each part of the scattered image in the visual field of the microscope is Will correspond to the position in. Therefore, the defect image in the visual field is detected together with the information on the depth as the position in the visual field.

Other or more detailed features, objects, functions and effects of the present invention will be clarified through the following examples.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic configuration diagram of a defect detecting apparatus according to an embodiment of the present invention. As shown in the figure, this device is a laser device 10 that outputs a laser beam 101 for observation.
3, a condenser lens 107 for irradiating the object 105 to be inspected with the laser beam 101, a microscope 109 for receiving scattered light from the object 105 due to the irradiating laser beam 101, and enlarging the scattered image, and its enlargement An image pickup element 111 for photoelectrically converting the scattered image to obtain an image signal of the scattered image, and means 11 for projecting a pattern used for focusing the microscope 109 on the object 105 to be inspected onto the object 105 to be inspected.
3. A stage 115 is provided which holds the object 105 to be inspected so that an angle θ formed by the normal line thereof and the optical axis of the microscope 109 is 5 to 35 ° and is moved by a driving unit (not shown).
The microscope 109 has an objective lens 117 and an imaging lens 11.
Have 9. The projection means 113 includes a spatial modulation element pattern 121, a light source 123, a convex lens 125 that irradiates the spatial modulation element pattern 121 with light emitted from the light source 123, a diffusion plate 127 and a convex lens 129, and the pattern 121 illuminated by the convex lens 125 to the microscope 109. The projection lens 131 and the half mirror 133 for forming an image at the focal position of The pattern 121 is a projection lens 131
Is located in the focal plane of.

FIG. 2 shows an object 105 to be inspected by the apparatus of FIG.
3 is a principle diagram for explaining the observation principle of FIG. 20 in the figure
Reference numeral 1 denotes a TV including the image pickup element 111 and the imaging lens 119.
This is a camera observation system, and this and the objective lens 117 constitute an observation system. The normal line of the surface of the object 105 to be inspected, the optical axis of the observation system, and the optical axis of the incident laser beam 101 are included in the same plane, and the angle β formed by the object 105 to be inspected and the optical axis of the incident laser beam 101 is The angle α formed by the optical axis of the refracted light and the normal line of the object 105 to be inspected is set to approximately 16 °. Field of view 2 of TV camera observation system 201
In 03, the measurement regions 1a to 4a are divided according to the depths of the layers 1b to 4b of the object 105 to be inspected.

In this configuration, in order to detect a defect, first, an image of the focusing pattern 121 is projected on the object 105 to be inspected, and the contrast of the projected image of the pattern 121 is between the measurement regions 2a and 3a. The position of the stage 115 is controlled so as to maximize the position. Next, the stage 115 is moved by a predetermined distance so that the focus position corresponds to the depth position of the boundary between the layers 2b and 3b. Next, the position of the laser beam 101 is adjusted so that the condensing point 205 of the laser beam 101 is located at the positions corresponding to the measurement regions 1a, 2a, 3a, and 4a that are the desired detection target layers. As a result, the measurement regions 1a to 4a in the visual field 203 correspond to the layers 1b to 4b. Therefore, as long as the depth of focus of the observation system covers each of the layers 1b to 4b in the object 105 to be measured, An image such as a defect will be obtained together with information on the layer in which it is present. The depth of field in this case is, for example, about 40 μm when the magnification of the observation system is 20 times, and about 15 μm when the magnification is 50 times. Further, the projection of the pattern 121 is stopped when it is no longer needed so as not to hinder the observation. This does not apply when the pattern 121 does not have a pattern that hinders observation.

Further, in order to perform detection in a range beyond the field of view 203, the laser beam 101 is reciprocated in a direction perpendicular to the maximum inclination direction of the object 105 to be inspected, and the object 105 to be inspected is inclined at its maximum. By moving in parallel to the direction, as shown in FIG.
, For example, a three-dimensional area of about 200 × 200 × 16 μm is scanned in a raster scan manner. As a result, the scattered image of the defect in that area is measured in any of the measurement areas 1a to 4a.
It is obtained together with the information on the depth position of whether it is detected in a.

FIG. 4 is an explanatory diagram for explaining the resolution in this detection. As shown in the figure, the resolution in the surface direction of the object 105 to be inspected, which is defined by the interval between the scanning lines in scanning with the laser beam 101, is about 0.4.
.mu.m and the refraction angle .alpha. of the laser beam 101 on the object 105 to be measured is about 16 DEG, the resolution in the depth direction is about 1.
It becomes 4 μm. This depth resolution can be improved to about 1 μm.

FIG. 5 is a schematic view showing a defect detecting method according to another embodiment of the present invention. Here, as a laser device,
A wavelength tunable laser such as a dye laser or a Ti sapphire laser is used, and the luminous flux 101 emitted by the laser is expanded through a collimator 301 and irradiated onto the object 105 to be inspected. And TV
It is not necessary to divide the measurement area in the visual field of the camera observation system 201. The normal direction of the surface of the object 105 to be inspected is TV.
It is aligned with the optical axis direction of the camera observation system 201. Other than that, the configuration is similar to that of FIG.

FIG. 6 shows an SOI (Silicon on I) having a multilayer structure of Si crystals, which is used as the object 105 to be inspected.
FIG. 2 is a cross-sectional view of a structure wafer. This wafer is S
An i substrate 401, an oxide film (SiO ₂ ) layer 403 having a thickness of 0.2 μm formed thereon, and a Si layer 405 having a thickness of 1 μm formed thereon are provided.

In this structure, when a defect is detected, the focus of the observation system is set on the surface of the wafer in the same manner as described above. However, here, the Si layer 4 within the depth of focus is
05 and the defects localized in the SiO ₂ layer 403 are detected, it is not necessary to further adjust the focus position. And
The laser beam 101 is irradiated so that the irradiation region thereof coincides with the field of view of the TV camera observation system 201 for observation.

FIG. 7 is an explanatory diagram showing a state where the wafer is irradiated with a laser beam. The figure (a) shows the case where the reflectance on the wafer surface is large, and the figure (b) shows the case where it is small. Further, the incident laser beam 101 on the left side of the graph incident intensity I ₀ of each figure (a) and (b)
7 is a graph showing a change in light intensity I of refracted light with respect to a wafer depth D. The curve 509 is an attenuation curve due to absorption.

As shown in the figure, the incident laser beam 101
Is separated into reflected light 501 and refracted light 503, but the wafer surface (Si crystal having a refractive index of 3.5) and the SiO ₂ layer 40 are separated.
3 (refractive index ≈1.5) By the interference of the reflected light on the surface,
The reflectance R on the surface of the wafer fluctuates with a larger width as shown in FIG. 8 in accordance with the wavelength λ of the laser light than in the case of a wafer having only Si crystals. And when the reflectance is large (λ
_{, 2} , λ ₄ , ..., λ ₁₂ ), as shown in FIG.
Defects 50 at the boundary between the i layer 405 and the SiO ₂ layer 403
When the intensity of scattered light 507 from _No. 5 is small and the reflectance is small (λ ₁ , λ ₃ , ..., λ ₁₁ ), it becomes large conversely as shown in FIG.

Therefore, the wavelengths λ ₁ and λ having low reflectance are
₃ , ..., Layers 405, 40 using the laser light 101 of λ ₁₁
3 Effectively detect scattered images from internal defects, and mainly detect scattered images from dust and scratches on the wafer surface using laser light of wavelengths λ ₂ , λ ₄ , ..., λ ₁₂ with high reflectance. .. Then, by comparing these scattered images, surface defects and internal defects are clearly distinguished. Further, as shown in FIG. 8, the vibration of the reflection intensity due to the interference has a wavelength of 400 nm.
Observed above. Therefore, since light with a wavelength of 400 to 2000 nm sufficiently enters the inside of the layer, internal defects are observed using laser light in this wavelength range, while light with a wavelength of less than 400 nm does not enter the inside of the layer.
The surface defects may be observed by using laser light of 0 to 650 nm or ordinary light, and the internal defects and the surface defects may be distinguished from each other.

Instead of changing the wavelength of the laser beam, as shown in FIG.
To the wavelength λ / 2 (=
(400-1300 nm) fundamental wave and second harmonic of wavelength λ as mixed light 805, which is made incident on the wafer, and scattered light from the surface defects and internal defects is scattered into the fundamental wave and the second harmonic, respectively. The observation may be performed by using another observation system as the light.

FIG. 10 shows an example of the scattered image thus obtained. However, as the wafer to be inspected 105, the Si layer 405 has a thickness of 1 μm, and the SiO ₂ layer 403 is
Has a thickness of 0.4 to 0.5 μm, and as shown in FIG. 11, half of the surface is the surface 11 as it is, but the other half is a surface 14 where the internal defect pits 13 are exposed by etching. Is used. FIG. 10A shows a wavelength of 9
The internal scattering image due to the laser light of 40 nm appeared remarkably 5
The state of the field of view of 00 μm square is shown in FIG.
The figure shows the field of view of the same portion where the surface scattered image by the laser light of 000 nm remarkably appeared. Part 11a is surface 1
1 and the portion 14a corresponds to the surface 14. Figure 10
In (b), an image of dust on the surface 11 appears in the portion 11a, and a myriad of minute pit images on the surface 11 appear in the portion 14a. In portions 11a and 14a of FIG. 10 (a), minute pit images on the surface do not appear, and large dust, scratches and internal defects on the surface appear innumerably.

FIG. 12 is a graph showing changes in reflectance R and scattering intensity S with respect to the wavelength λ of incident light on this wafer. In the figure, a curve 151 indicates a change in reflectance by calculation, a curve 153 indicates a change in reflectance by actual measurement, and a curve 155.
Shows the change in the scattering intensity from the surface defects, and the curve 157 shows the change in the scattering intensity from the internal defects. From this graph, it can be seen that laser light having a wavelength of 940 nm is suitable for detecting internal defects and laser light having a wavelength of 1000 nm is suitable for detecting surface defects.

FIGS. 13A and 13B show a wavelength 100 that reaches the inside of another inspected object 105 at the same location.
The states of the visual field of 500 μm square when observed with a laser beam of 0 nm and a laser beam of a wavelength of 451 nm are respectively shown. By comparing the two, the scattered image from the internal defect can be recognized.

As shown in FIG. 14, the object 105 to be inspected is
In the case of a wafer having a fine structure on the surface, in the portion where the fine structure is present, a nominal defect and a surface defect are similarly observed, assuming that a layer having an equivalent thickness is present. be able to. In this case, however, a filter (mask) 181 for blocking the diffracted light 183 is provided in the observation optical system in order to prevent the diffracted light due to the fine structure from entering the observation optical system and making it impossible to observe the internal defect 505. Is provided. The regular reflection light 185 does not cause any problem.

15 to 17 are schematic views showing the structure of a defect detecting apparatus according to still another embodiment of the present invention. These devices detect defects inside and on the surface of the object to be inspected 105 with laser light having a wavelength of 400 to 2000 nm, and detect surface defects with laser light having a wavelength of 200 to 650 nm.

In the apparatus shown in FIG. 15, the laser beam 1
The beam diameter of 01 is expanded by the concave lens 163, collimated by the collimator lens 161, and introduced into the optical path of the observation system through the half mirror 171, and is irradiated onto the object 105 to be inspected through the objective lens 117. Then, as described above, the wavelength of the laser beam 101 is changed to obtain the specular reflection image of the surface defect and the specular reflection image of the internal defect.
17, through the imaging lens 119 and the image sensor 111,
It is designed to be obtained as an electric signal.

In the device of FIG. 16, wavelengths λ ₁ and λ ₂
The object 105 to be inspected is illuminated with the laser beam 101 obtained by mixing the laser light of the above-mentioned through the half mirror 169, and the specularly reflected light thereof is wavelength λ ₁ by the dichroic mirror 173.
And the λ ₂ component, and the surface of the object 105 to be measured is divided by the wavelength λ ₁ component into the imaging lens 119 and the image pickup device 1.
11 and observes the specular reflection image from the inside of the object 105 to be inspected due to the wavelength λ ₂ component.
5 and the image sensor 167 for observation.

In the apparatus of FIG. 17, the laser beam 1
The light flux in the central portion of 01 is blocked by the mask 175, and only the light flux in the peripheral portion is mirror 177 and objective lens 11
The object 105 to be inspected is irradiated through the peripheral portion of the object 7, and the specular reflection image thereof is obtained through the central portion of the objective lens 117. Others are the same as the case of FIG.

[0039]

As described above, according to the present invention, the first and second lights having wavelengths that generate relatively large amounts of optical information on the surface and inside of the object to be inspected are incident on the object to be inspected, Since the internal defect is detected by comparing the optical information obtained for each incident light, the internal defect in the multilayer semiconductor substrate or the like such as a semiconductor wafer having a multilayer structure,
It can be clearly distinguished from surface defects and detected.

Further, the refracted light of the incident laser beam in the object to be inspected has a predetermined small cross section, and the scattered image intersects the optical axis of the refracted light at a predetermined angle. Obtained by the microscope on the optical axis to, so as to specify the depth position of the defect image included in the obtained scattering image based on the position in the field of view of the defect image,
It is possible to detect the layer and the depth where the defect exists with high resolution.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a defect detection device according to an embodiment of the present invention.

FIG. 2 is a principle diagram for explaining an observation principle of an object to be inspected by the apparatus of FIG.

FIG. 3 is an explanatory diagram showing a manner in which an object to be inspected is scanned in a raster scan manner in the apparatus of FIG.

FIG. 4 is an explanatory diagram for explaining resolution in detection by the apparatus of FIG.

FIG. 5 is a schematic diagram showing a defect detection method according to another embodiment of the present invention.

6 is a cross-sectional view of an SOI structure wafer having a multilayer structure of Si crystals, which is used as a test object in the apparatus of FIG.

7 is an explanatory diagram showing a state when a laser beam is applied to a wafer in the apparatus of FIG.

FIG. 8 is a graph showing how the reflectance on the surface of the wafer as shown in FIG. 6 fluctuates with a large width according to the wavelength λ of the laser light, as compared with the case of a wafer having only Si crystals.

FIG. 9 is an explanatory diagram showing how laser light of wavelength λ is mixed with a fundamental wave of wavelength λ / 2 and a second harmonic of wavelength λ through a second harmonic generation element.

10 is a schematic diagram showing an example of a scattered image obtained when the wafer of FIG. 11 is observed in the apparatus of FIG.

11 is a schematic diagram showing a wafer from which the scattered image of FIG. 10 has been obtained.

12 is a graph showing changes in reflectance R and scattering intensity S with respect to the wavelength λ of incident light in the wafer of FIG.

13 is a schematic diagram showing a state when another test object is observed in the apparatus of FIG.

FIG. 14 is a schematic diagram showing how defects are observed when the object to be inspected is a wafer having a fine structure on its surface.

15 to 17 are schematic diagrams showing a configuration of a defect detection apparatus according to still another embodiment of the present invention.

[Explanation of symbols]

101: laser light, 103: laser device, 105: object to be inspected, 107: condenser lens, 109: microscope, 111:
Image sensor, 113: Projection means, 115: Stage,
117: Objective lens, 119: Imaging lens, 121: Spatial modulation element pattern, 123: Light source, 125, 129:
Convex lens, 127: diffuser plate, 131: projection lens, 1
33: Half mirror, 163: Concave lens, 161: Collimator lens, 167: Image sensor, 169: Half mirror, 171: Half mirror, 173: Dichroic mirror, 175: Mask, 177: Mirror, 183: Diffracted light, 181: Filter (Mask), 185: specular reflection light,
201: TV camera observation system, 203: field of view, 1b to 4
b: layer, 1a to 4a: measurement region, 301: collimator,
401: Si substrate, 403: oxide film (SiO ₂ ) layer, 4
05: Si layer, 501: reflected light, 503: refracted light, 50
5: Defect, 507: Scattered light, 801: Laser light of wavelength λ, 803: Second harmonic generation element, 805: Mixed light

[Procedure amendment]

[Submission date] March 5, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 9

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 23

[Correction method] Change

[Correction content]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

In another aspect of the present invention, a laser beam is incident on an object to be inspected, a scattered image resulting from scattered light from the object to be inspected thereby is obtained through a microscope, and based on this, an image of the object to be inspected is obtained. In the method of detecting internal defects,
In addition to the above, the refracted light of the incident laser beam is made to have a predetermined small cross section in the object to be inspected, and the scattered image generated by the refracted light is measured at a predetermined angle with the optical axis of the refracted light. Obtained by the microscope on substantially intersecting optical axes, specify the depth position in the object to be inspected of the defect image included in the obtained scattering image based on the position in the field of view of the microscope in which the defect image exists This is further characterized by performing the incident laser beam or the object to be inspected two-dimensionally.

Claims (26)

[Claims] 1. A predetermined light is made incident on an object to be inspected, optical information from the object to be inspected thereby is obtained through an observation optical system, and internal defects of the object to be inspected are obtained based on the obtained optical information. In the method for detecting, a first incident light having a wavelength that causes a relatively large amount of optical information on the surface of the object to be inspected, and a second incident light having a wavelength that causes a relatively large amount of optical information inside the object to be inspected. Is incident on the object to be inspected, the optical information generated by each incident light is obtained, and the internal information is detected by comparing the optical information of both of them and the internal defect is detected. 2. The optical information is based on scattered light,
The internal defect detection method according to claim 1, wherein the optical information is obtained without being affected by the diffracted light due to the fine structure of the surface of the object to be inspected, by appropriately selecting the wavelengths of the second incident light and the second incident light. 3. The optical information is due to scattered light, and the scattering direction of scattered light to be obtained as optical information is selected by a spatial filter so that it is not affected by diffracted light due to the fine structure of the surface of the object to be inspected. The internal defect detection method according to claim 1, wherein optical information is obtained. 4. The beam diameter of the incident surface of the first and second incident lights is approximately the same as the field of view of the observation optical system, and it is not necessary to scan the object to be examined two-dimensionally. Internal defect detection method. 5. The object to be inspected is a wafer having a multilayer structure of Si crystals, and the wavelengths of the first incident light and the second incident light are 4
The internal defect detection method according to claim 1, wherein the internal defect detection range is from 00 to 2000 nm. 6. The object to be inspected is a wafer having a multilayer structure of Si crystals, and the wavelength of the first incident light is 200 to 650 n.
The internal defect detection method according to claim 1, wherein the range is m. 7. The object to be inspected is a wafer having a multilayer structure of Si crystals, and the second incident light has a wavelength of 400 to 1330 n.
The internal defect detection method according to claim 1, wherein the first incident light is m second laser light, and the first incident light is a second harmonic thereof, and the fundamental wave and the second harmonic are simultaneously incident on the object to be inspected. 8. The internal defect detection method according to claim 1, wherein the first incident light and the second incident light are emitted from a wavelength tunable laser device. 9. A method of detecting an internal defect of an object to be inspected based on a scattered image of scattered light from the object to be inspected, which is produced by causing a laser beam to enter the object to be inspected. , The incident laser beam is made to have its refracted light having a predetermined small cross section inside the object to be inspected, and the scattered image generated by the refracted light is given at a predetermined angle with the optical axis of the refracted light. Obtained by the microscope on substantially intersecting optical axes, to specify the depth position in the object to be inspected of the defect image included in the obtained scattered image based on the position in the field of view of the microscope in which the defect image exists. An internal defect detection method characterized in that the object to be inspected is two-dimensionally scanned with an incident laser beam. 10. The normal line of the object surface to be inspected forms an angle of 5 to 35 ° with respect to the optical axis of the microscope, and a predetermined pattern is imaged in the focal plane of the microscope. The internal defect detection method according to claim 9, wherein the distance between the microscope and the object to be inspected is adjusted based on the projected image of. 11. As optical information generated by incident light,
The internal defect detection method according to claim 1 or 9, which includes not only scattered light but also fluorescent light obtained by dispersing light from the defect. 12. The internal defect detection method according to claim 1, wherein the optical information generated by the incident light is specularly reflected light generated from the object to be inspected by the incident light. 13. The internal defect detection method according to claim 1, wherein the optical information obtained is image data by photoelectric conversion. 14. A predetermined light is made incident on an object to be inspected, optical information from the object to be inspected thereby is obtained through an observation optical system, and internal defects of the object to be inspected are obtained based on the obtained optical information. In the detection method, the normal line of the object surface to be inspected makes an angle with the optical axis of the observation optical system, and when focusing the observation optical system, a predetermined pattern is imaged on the focal plane of the microscope. An internal defect detection method characterized in that the distance between the microscope and the object to be inspected is adjusted based on the projected image of this pattern on the object surface to be inspected. 15. Illuminating means for causing a predetermined light to enter the object to be inspected, an observation optical system for obtaining optical information from the object to be inspected generated by the incident light, and optical information obtained by this photoelectric conversion. In the internal defect detection device including a photoelectric conversion unit that obtains image data of the internal defect of the object to be inspected, the illumination unit includes the first incident light having a wavelength that generates a relatively large amount of optical information on the surface of the object to be inspected. And a second incident light having a wavelength that generates a relatively large amount of optical information inside the object to be inspected, and the means for obtaining image data includes first and second incident light. An internal defect detection device characterized in that image data is obtained for each. 16. The light information obtained through the observation optical system is due to scattered light, and the illuminating means appropriately selects and irradiates the wavelengths of the first and second incident lights, respectively. 16. The internal defect detection device according to claim 15, wherein the means for obtaining the image data obtains the image data without being affected by the diffracted light due to the fine structure of the surface of the object to be inspected. 17. The optical information obtained through the observation optical system is due to scattered light, and the observation optical system has a spatial filter for selecting a scattering direction of scattered light to be obtained as optical information, whereby The internal defect detection device according to claim 15, wherein the optical information is obtained without being affected by the diffracted light due to the fine structure of the object surface. 18. A first illuminating means for illuminating an object to be inspected
16. The internal defect detection device according to claim 15, wherein the beam diameter of the incident surface of the second incident light is about the same as the field of view of the observation optical system, and the object to be inspected does not need to be two-dimensionally scanned. 19. The internal defect detection according to claim 15, wherein the object to be inspected is a wafer having a multilayer structure of Si crystals, and the wavelengths of the first incident light and the second incident light are within the range of 400 to 2000 nm. Method. 20. The object to be inspected is a wafer having a multilayer structure of Si crystals, and the wavelength of the first incident light is 200 to 650.
The internal defect detection method according to claim 15, wherein the internal defect detection range is in the range of nm. 21. The object to be inspected is a wafer having a multilayer structure of Si crystals, and the first incident light has a wavelength of 400 to 1330.
16. The internal defect according to claim 15, wherein the internal incident light is a laser light of nm, the second incident light is a second harmonic thereof, and the illumination means simultaneously makes the fundamental wave and the second harmonic incident on the object to be inspected. Detection device. 22. The internal defect detection device according to claim 15, wherein the illumination means has a wavelength tunable laser device which emits first incident light and second incident light. 23. Illuminating means for making a laser beam incident on an object to be inspected, means for two-dimensionally scanning the object to be inspected by the incident laser beam, and a microscope for obtaining a scattered image generated by the incident laser beam. In the internal defect detection device provided with photoelectric conversion means for photoelectrically converting the scattered image obtained thereby into image data, the incident laser beam emitted by the illumination means is a predetermined small cross-section of the refracted light in the object to be inspected. The microscope is arranged so as to obtain a scattered image generated by the refracted light on an optical axis that intersects the optical axis of the refracted light at a predetermined angle and substantially intersects, and the photoelectric conversion means The depth position of the defect image contained in the image data obtained by the inspected object is specified based on the position within the field of view of the microscope in which the defect image exists. Internal defect detection device. 24. The normal to the object surface to be inspected forms an angle of 5 to 35 ° with respect to the optical axis of the microscope, and has means for forming a predetermined pattern in the focal plane of the microscope, and the microscope and the object to be inspected. 24. The internal defect detection method according to claim 23, wherein the distance between the objects is adjusted based on a projected image of this pattern on the surface of the object to be inspected. 25. The internal defect detection device according to claim 15, wherein the observation optical system is one that obtains fluorescence by dispersing light from a defect as well as by scattered light as optical information. 26. The optical information generated by the incident light is specularly reflected light generated from the object to be inspected by the incident light.
The described internal defect detection method.