JPH0760136B2 - Internal defect inspection method and apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an internal defect inspection method and apparatus, and more specifically, by detecting and processing information regarding internal defects of an object that is an object to be measured. The present invention relates to an internal defect inspection method and apparatus capable of visualizing the inside of an object by destruction and stably inspecting the defect inside the object under a certain condition.

[Prior Art] Conventionally, an internal defect inspection in which an object that is an object to be measured is irradiated with light such as a laser beam and the transmitted light or scattered light is obtained to obtain information about a defect inside the object to visualize the defect. Methods and devices are known.

FIG. 4 is a sectional view showing a schematic configuration of this type of internal defect inspection apparatus. The apparatus shown in the same figure is an apparatus for irradiating light on an object to be measured and visualizing defects by using the transmitted light, and is disclosed in JP-A-1-224646.

In the figure, the illumination lamp 4
The light is emitted at 02. The measurement object 401 is a plate-like object, and in this figure, a cross section taken in the thickness direction (direction perpendicular to the surface of the plate) is shown. The light transmitted through the measurement object 401 enters the imager 403. As a result, a magnified image of the measurement object 401 by the transmitted light is captured. The image capturing device 403 outputs the captured result as image information. The image information is processed by the processor 404, and the image of the photographed object 401 is visualized by a CRT display device or the like (not shown). Reference numerals 405 and 406 denote defects inside the measuring object 401.

In FIG. 4, the sizes of the defects 405 and 406 are drawn relatively large for the purpose of explanation. However, the size of the defect to be inspected by the internal defect inspection apparatus of this type is actually several microns or less. It is a minute thing.

Further, when inspecting an internal defect in a semiconductor material such as a silicon wafer by the above method, it is impossible to detect the internal defect with visible light. Therefore, a light source that emits infrared rays is used as a light source to obtain information on internal defects.

FIG. 5 (a) shows a defect inside an object by irradiating a laser beam into an object which is an object to be measured and measuring scattered light scattered inside the object from a direction substantially orthogonal to the irradiation direction of the laser. It is sectional drawing which shows schematic structure of the apparatus which visualizes. FIG. 5 (b) is a perspective view of the measurement object of FIG. 5 (a). Such an apparatus is disclosed in JP-A-1-151243.

According to the device shown in the figure, an object to be measured such as a silicon wafer
A laser beam in the infrared wavelength range (for example, a wavelength of about 1 μm) is incident on 501 as indicated by arrow 504. The measurement target 501 is a plate-like object, and in this figure, a cross section taken in the thickness direction (direction perpendicular to the surface of the plate) is shown.
Therefore, the laser beam 504 is incident from the lower surface (back surface) of the plate-shaped measurement target 501 toward the upper surface (front surface). The laser beam 504 is scattered by a defect inside the measuring object 501. This scattered light is emitted from the measuring object 501 as indicated by an arrow 505. This scattered light is detected by the imager 502 arranged at a position orthogonal to the direction of the laser beam 504.
An arrow 521 in FIG. 5B indicates the direction of observation by the imager 502. In this way, the image capturing device 502 captures an enlarged image of the object 501 due to scattered light. The photographing device 502 outputs the photographed result as image information. The image information is processed by the processor 503.
Is processed by a CRT display device (not shown),
The image of the captured object 501 is visualized.

[Problems to be Solved by the Invention] By the way, according to the transmitted light type internal defect inspection apparatus as shown in FIG. 4, the internal defect 405 and the like of the measurement object 401 can be inspected nondestructively. However, the measured object 401
Regarding the vertical distribution of defects inside (the distribution of defects in the vertical direction on the paper surface of FIG. 4), there is a problem that no information can be obtained.

Further, in this method, since the internal defect is detected by using the transmitted light, the light incident on the imaging device 403 is a transmitted light (projected image) obtained by accumulating information about the vertical direction (thickness direction) of the measurement object 401. Become. Therefore, when another large internal defect 405 exists on the side of the image capturing device 403, like the internal defect 406 in FIG. 4, the internal defect 406 is buried in the internal defect 405, and the internal defect 406 is detected. It is impossible to carry out an accurate inspection.

On the other hand, according to the internal defect inspection apparatus using scattered light as shown in FIG. 5 (a), a laser beam is made to enter an object and scattered light is detected from a direction substantially orthogonal to the direction of the laser beam. Since the internal defect is inspected, even if the second internal defect exists around the first internal defect, if the camera is focused on the position where the first internal defect exists, The first internal defect can be detected. Further, if the internal defects of the object 501 are inspected in the arrangement as shown in FIG. 5A, the vertical distribution of the defects in the object 501 (the distribution in the vertical direction on the paper surface of FIG. 5A) may be obtained. it can.

However, according to the apparatus of FIG. 5A, in order to obtain the vertical distribution of defects in the measurement object 501, the laser beam 5
04 must be flat so that the cut surface 506 of the measurement object 501 does not cause scattering. Therefore, in order to obtain the distribution of defects (vertical distribution) in the thickness direction of a plate-shaped material such as a silicon wafer, it is necessary to cut or cleave near the measurement position. No. 522 in FIG. 5 (b)
Indicates a cleavage plane of the measurement object 501. Thus, the fifth
As a result, in the method of FIGS.
There is a problem that the vertical distribution of internal defects cannot be obtained without destroying.

Further, as shown in FIG. 5 (c), it is also possible to make a laser beam incident on the measurement object 501 from the cut surface or the cleavage plane 506 as shown by arrow 511 and measure the scattered light from the direction of arrow 512. In the vicinity of the surface 513 of the measurement object 501, it is extremely difficult to make the laser light incident as shown by an arrow 511. Therefore, there is a problem that a defect existing in the vicinity of the surface 513 of the measurement object 501 cannot be measured.

The present invention has been made in view of the above-mentioned problems in the conventional type, and an object thereof is to provide an internal defect inspection method and apparatus capable of obtaining a vertical cross-sectional distribution of internal defects at an arbitrary position without destroying a measurement object. And

[Means for Solving the Problem] In order to achieve the above object, in the present invention, a laser beam that is narrowed down is made incident on a measurement object, and scattered light from the inside of the measurement object by the laser beam is made incident on the optical means. In the internal defect inspection method for inspecting defects inside the measurement object by enlarging and obtaining as image information, the laser beam incident from the first surface of the measurement object to the inside of the second surface of the measurement object A laser beam is made incident on the object to be measured so as to be totally reflected on the surface, and scattered light by the laser beam passing through the vicinity of the second surface is made incident on the optical means to inspect defects near the second surface. It is characterized by doing.

Further, the internal defect inspection apparatus according to the present invention includes a laser emitting unit that emits a laser beam that is narrowed down, an incident position moving unit that moves the incident position of the laser beam on the first surface of the measuring object, Incident direction control means for controlling the incident direction of the laser beam on the measurement object so that the laser beam incident from the first surface of the measurement object is totally reflected on the second surface of the measurement object. Optical means for receiving scattered light from the inside of the measuring object by the laser beam and obtaining it as image information, and in conjunction with the movement of the incident position of the laser beam, at a position in the optical path of the laser beam inside the measuring object. Focusing means for focusing the optical means, the optical means being located at a measurement position in the optical path of a laser beam passing near the second surface of the object to be measured and totally reflected by the second surface. Focused stage, by incident light scattered by said laser beam to said optical means, characterized by inspecting defects of a second near the surface.

[Operation] According to the above-described internal defect inspection method of the present invention, the laser beam is made incident from the first surface of the measurement object, and the laser beam is totally reflected by the second surface of the measurement object. The beam is incident on the measuring object. Accordingly, since the laser beam can be irradiated to the vicinity of the second surface (including the position on the second surface), such defects near the surface can be inspected.

Further, according to the internal defect inspection apparatus of the present invention, a laser beam that is narrowed down is emitted from the laser emission means, and this laser beam is applied to the measurement object. The incident position of the laser beam on the measuring object can be moved by the incident position moving means. The laser beam incident on the object to be measured is scattered by internal defects to generate scattered light. The scattered light can be detected by an optical means to inspect the internal defect of the measuring object. Here, the incident position of the laser beam on the measuring object can be moved by the incident position moving means, and in conjunction with this, the focus of this optical means is set to the measuring position on the optical path in the measuring object of the laser beam. I am trying to match. Therefore, the laser beam can be irradiated to an arbitrary position in the measurement object and the focus of the optical means can be adjusted to the position, so that the defect at the arbitrary position can be detected. Further, since the movement of the incident position of the laser beam and the operation of focusing the optical means can be continuously performed in an interlocked manner, the defect in the arbitrary direction (for example, the vertical direction) of the measuring object can be detected. The distribution can also be examined.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 (a) is a sectional view showing an optical path of a laser beam inside an object to be measured and an imager of an internal defect inspection apparatus according to an embodiment of the present invention, and also relates to an embodiment of the present invention. It is also a sectional view for explaining the internal defect inspection method.

In the figure, 101 is a measurement object, 102 is a microscope, and 103 is a detection element (imager) for detecting scattered light through the microscope 102. The measurement object 101 is a plate-like object, and in this figure, a cross section taken in the thickness direction (direction perpendicular to the surface of the plate) is shown. 111 is a side surface of the measurement object 101, 11
2 shows the upper surface. The laser beam emitted from the laser beam emitting means (not shown) enters from the side surface 111 of the measuring object 101. Reference numerals 121 to 124 denote optical paths of laser beams incident on the measurement object 101, and 131 to 134 denote optical paths of laser beams inside the measurement object 101. The laser beam can be moved in parallel in the direction of the arrow 113, so that the incident position on the side surface 111 of the measuring object 101 can be changed.

The microscope 102 can change its focal length, and can focus on measurement points such as P1 to Pn and obtain an optically enlarged image of an observation portion near these measurement points. The scattered light detecting element 103 converts the magnified image obtained by the microscope 102 into an electric signal, and inspects the defect by various methods described later based on the electric signal.

FIG. 1 (b) is a perspective view of the measurement object 101 of FIG. 1 (a). The measurement object 101 is a silicon wafer used for manufacturing a semiconductor device. The laser beam 120 is incident from an orientation flat (abbreviated as orientation flat) 150 of the silicon wafer 101. Then, the light is reflected by the upper surface of the wafer 101 as indicated by an arrow 130 and emitted from the direction opposite to the orientation flat 150. An arrow 151 indicates the observation direction of the microscope 102.

The basic operation of the internal defect inspection in the apparatus of the present embodiment will be described with reference to FIGS. 1 (a) and 1 (b).

First, in order that the laser beam incident on the measurement object 101 is totally reflected on the upper surface 112 of the measurement object 101, the measurement object is previously measured.
The incident angle of the laser beam on the side surface 111 of 101 is set. The initial incident position of the laser beam is position Q1. The laser beam incident on the position Q1 at a predetermined incident angle as shown in the optical path 121 travels inside the measurement object 101 as an optical path 131. Then, the light is totally reflected at the position P1 on the upper surface 112 of the measurement object 101. At this time, the focus of the microscope 102 is aligned with the position P1, and thus an image in the vicinity of the position P1 on the upper surface 112 of the measurement object 101 can be obtained. The magnified image obtained by the microscope 102 is converted into an electric signal by the detection element 103 and output.

Next, the laser beam is translated in the direction of arrow 113 while maintaining the direction of the laser beam defined by the predetermined incident angle. For example, it is assumed that the laser beam moves in parallel from the optical path 121 and is incident on the position Q2 of the side surface 111 of the measuring object 101 as in the optical path 122. At this time, the laser beam incident on the measurement object 101 passes through the optical path 132 and is positioned on the upper surface 112.
Total reflection occurs at R2, and travels through position P2.

The focus position of the microscope 102 is changed in association with the parallel movement of the laser beam as indicated by the arrow 113. Laser beam is in position P
When passing through 2, the microscope 102 is focused on this position P2. As a result, the position P2 inside the measuring object 101 is
The vicinity of is observed. The magnified image obtained by the microscope 102 is
The detection element 103 converts the electric signal and outputs the electric signal.

Furthermore, it is assumed that the laser beam moves in parallel and enters from the position Q3 of the side surface 111 through the optical path 123. At this time, the laser beam 133 that has entered the inside of the measurement object 101 has the upper surface 112.
Total reflection occurs at position R3 and proceeds through position P3. Then, the focus of the microscope 102 is aligned with the position P3. As a result, an image near the position P3 is obtained. The magnified image obtained by the microscope 102 is converted into an electric signal by the detection element 103 and output.

Further, the laser beam is translated and is made incident on the position Qn of the side surface 111 of the measurement object 101 as in the optical path 124. At this time, the laser beam incident on the measuring object 101 is totally reflected at the position Rn on the upper surface 112 like the optical path 134, and proceeds through the position Pn. At this time, the focus of the microscope 102 is aligned with the position Pn. As a result, an image near the position Pn is obtained. microscope
The magnified image obtained by 102 is converted into an electric signal by the detection element 103 and output.

In this way, the incident position of the laser beam is sequentially changed, and the laser beam is totally reflected on the upper surface of the measurement object, and the positions P1 to Pn are indicated by arrows.
114 and arrow 115 are sequentially passed. On the other hand, the focus of the microscope 102 is interlocked with such movement of the laser beam so that when the laser beam passes through the positions P1 to Pn, the passing positions P1 to Pn are focused. Detection element 10
3 converts this optical image into an electric signal and outputs it. Thereby, an electric signal representing an image of the measurement object 101 in the thickness direction (vertical direction) is obtained, and the defect can be inspected based on the electric signal.

FIG. 2 is a cross-sectional view showing how the laser beam scatters from a defect inside the measuring object.

In the figure, 201 is an object to be measured (a cross section is shown here), 202 is a luminous flux of a laser beam, 203 is an arrow indicating scattered light, 204 is a defect inside the object to be measured 201, and 205 is the progress of the laser beam. The direction 206 indicates the observation direction of scattered light.

Scattered light is generated from the defect 203 in the light beam 202 of the laser beam traveling as indicated by the arrow 205, as indicated by the arrow 203.
A component of the scattered light 203 in the observation direction 206 is incident on the image pickup device through the microscope as described in FIG.

FIG. 3 is a block diagram showing the configuration of the apparatus of this embodiment.

In the figure, 301 is an object to be measured, 303 is a laser oscillator,
Reference numeral 302 denotes a laser beam emitted from the laser oscillator 303. Reference numerals 305 and 307 are total reflection mirrors for changing the traveling direction of the laser beam 302, 304 is a drive motor for driving the total reflection mirror 305 to swing the laser beam 302 in a direction perpendicular to the paper surface, and 306 is total reflection. A piezoelectric element for driving the mirror 307 in the direction of arrow S to move the incident position of the laser beam 302 on the side surface of the object 301 to be measured in parallel as shown in FIG. Reference numeral 309 is a microscope that focuses on a predetermined position of the measurement object 301 to obtain an enlarged image thereof, 310 is an imager that converts the enlarged image by the microscope 309 into an electric signal (information signal including information that is an imaging result), 308 Arrow T on the microscope 309 barrel
A lens barrel drive unit for driving as described above to change the focus position in the measurement object 301 of the microscope 309 is shown.

Reference numeral 311 denotes an image memory circuit that stores an information signal, which is an image pickup result input from the image pickup device 310 via the connection line 351, as matrix image information corresponding to the image pickup screen, and 312 indicates image information input via the connection line 352. An image processing circuit 313 performs a predetermined process, and an arithmetic processing circuit 313 performs a predetermined arithmetic process based on a binary signal input from the image processing circuit 312 via the connection line 354.

Reference numeral 314 is an autofocus control circuit that outputs a lens barrel drive signal via the connection line 363 to drive the lens barrel drive unit 308, and 316 is a defect information signal and arithmetic circuit output from the image processing circuit 312 via the connection line 353. A display processing circuit that generates and outputs a video signal based on a measurement signal output from 313 via a connection line 355, and 317 is a vertical line of a defect based on a video signal input from this display processing circuit 316 via a connection line 356. A display circuit for displaying a cross-sectional image and a calculation result, 318 is a display processing circuit 3
This is a recorder for obtaining a so-called hard copy by inputting a predetermined recording signal from 16 through a connection line 357.

322 is a motor signal generation circuit that outputs a drive signal to the drive motor 404 via a connection line 360, 321 is a high voltage generation circuit that outputs a scanning signal to the piezoelectric element 306 via a connection line 359, 320
Is a laser power source for supplying power to the laser oscillator 303. 315 is a high voltage generation circuit 321 via connection lines 364 to 367,
A synchronization signal generation circuit that outputs synchronization signals to the motor signal generation circuit 322, the image memory circuit 311, and the autofocus control circuit 314, respectively. A control circuit 319 outputs a control signal to the synchronization signal generation circuit 315, the display processing circuit 316, and the laser power source 320 via the connection line 358.

The operation of the internal defect inspection apparatus of this embodiment will be described with reference to FIG. A case will be described in which the measurement object 301 is a plate-like object, an image of a vertical cross section (cross section along the thickness direction) of the object is obtained, and defects in this cross section are inspected.

Referring to FIG. 3, measurement object 301 is arranged immediately below microscope 309 such that its upper surface faces the observation method of microscope 309. Similar to FIG. 1, FIG. 3 shows a vertical cross section of the measuring object. After arranging the measuring object 301, the control circuit 319 turns on the laser power source 320 and causes the laser oscillator 303 to emit the laser beam 302.

Then, the total reflection mirror 30 is configured so that the laser beam 302 is totally reflected at a predetermined position P1 on the upper surface of the measurement object 301.
Adjust the position of 5,307. This adjustment may be performed manually or automatically under the control of the control circuit 319. With the alignment of the laser beam 302,
The focus of the microscope 309 is adjusted to the position P1 on the upper surface of the measurement object 301. This focusing may be performed manually or automatically under the control of the control circuit 319.

The laser beam emitted from the laser oscillator 303, incident on the inside of the measurement object 301 through the total reflection mirrors 305 and 307 from the side surface thereof, and totally reflected at the position P1 on the upper surface of the measurement object 301 is the measurement object 301. Is ejected from the other side of the. At this time, the light flux of the laser beam 302 is transmitted to the microscope 3
There is no direct incidence on the imager 310 through 09. However, when there is an internal defect in the vicinity of the position P1 of the measurement object 301, scattered light from the defect portion in the luminous flux of the laser beam 302 incident on the inside of the measurement object 301 is scattered as described in FIG. Occurs. At this time, the focus of the microscope 309 is the position P.
Aligned to 1. The microscope 309 captures the component of this scattered light that is directed to the microscope 309, and obtains an enlarged image of the focal position. This magnified image is detected by the image pickup device 310.

The imager 310 converts the image near the position P1 obtained by the microscope 309 into an electric signal and outputs it as an information signal to the connection line 351.
This information signal indicates the intensity of scattered light from the position P1. This information signal is input to the image memory circuit 311. The image memory circuit 311 stores a value indicating the intensity of scattered light in a storage position corresponding to the position P1 according to this information signal.

Here, the laser beam incident on the measuring object 301 is sequentially moved in parallel as described with reference to FIG. 1, and the focus position of the microscope 309 is also moved in association with the movement of the laser beam (laser beam). The operation that is interlocked with the movement of the microscope and the movement of the focus of the microscope will be described later). Therefore,
After the observation of the scattered light at the position P1 of the measuring object 301, the position P
The scattered light is observed for each position from 1 to the lower side of the paper (in the vertical direction of the measuring object 301). Thus, the scattered light from each position in the vertical direction as described with reference to FIGS. 1 and 2 is observed, and the intensity of the scattered light from each position is stored in a predetermined column of the image memory circuit 311. Image memory circuit 3
The scattered light intensity information stored in one row of 11 (a series of storage positions) is in the vertical direction (dotted line 3) passing through the position P1 of the measurement object 301.
70) Defect information is shown.

Further, by driving the total reflection mirror 305 as described later, the optical path of the laser beam 302 can be slightly shifted in the direction perpendicular to the paper surface. And the dotted line observed earlier
In addition to information in the vertical direction along 370, defect information in the vertical direction at a position slightly deviated from that position in the front or back direction of the paper surface is obtained. This information is stored in the next column of the previously stored column of the image memory circuit 311. By repeating such operations, image information arranged in a matrix is stored in the image memory circuit 311. This image information is image information of a cross section (two-dimensional) perpendicular to the paper surface including the dotted line 370 of the measurement object 301 in FIG.

This image information is input to the image processing circuit 312 via the connection line 352. The image processing circuit 312 processes the input image information so that the background noise becomes constant, and the internal defect in the cross-sectional image of the measurement object 301 is emphasized. As a result, the defect information signal is output to the display processing circuit 316 via the connection line 353. Further, the image processing circuit 312 binarizes the input image information as a binary signal and outputs the binary signal via the connection line 354.
Output to 13.

This arithmetic processing circuit 313 calculates the area ratio, the number of internal defects, the size of defects, and the like of the internal defects with respect to the entire observation range from the input binary signal, and outputs the result to the display processing circuit 316 via the connection line 355. To do. Display processing circuit 316
Processes signals from the image processing circuit 312 and the arithmetic processing circuit 313, generates a video signal, and outputs the video signal to the connection line 356. This video signal is input to the display circuit 317 to display the vertical cross-sectional image of the defect and the calculation result as described above. further,
The image information and the calculation result output from the display processing circuit 316 are input to the recorder 318 via the connection line 357 as a storage signal. The recorder 318 outputs a hard copy record based on the input recording signal.

The control circuit 319 generates a control signal for controlling the entire system and outputs the control signal to the display processing circuit 316, the laser power supply 320, and the synchronization signal generation circuit 315 via the connection line 358.
The synchronization signal generation circuit 315 outputs a synchronization signal to the image memory circuit 311, the high voltage generation circuit 321, and the motor signal generation circuit 322 based on the instruction of the control signal from the control circuit 319.

Upon receiving this synchronization signal, the high voltage generation circuit 321 first outputs a scanning signal for driving the piezoelectric element 306 via the connection line 359. On the other hand, upon receiving the synchronization signal from the synchronization signal generation circuit 315, the motor signal generation circuit 322 outputs a drive signal to the drive motor 304 of the total reflection mirror 305. Further, based on the synchronization signal output from the synchronization signal generation circuit 315, the autofocus control circuit 314 drives the lens barrel drive unit 308,
The focus of the microscope 309 is adjusted to a predetermined position of the optical path inside the measuring object 301 of the laser beam. In addition, the synchronization signal generation circuit 315
Based on the synchronization signal output from the image memory circuit 31
1 stores the information signal output from the imager 310 in the corresponding row and column storage locations.

The interlocking operation of each unit by the synchronizing signal of the synchronizing signal generating circuit 315 is as follows.

First, the total reflection mirror 305 is positioned by driving the driving motor 304. As a result, a surface (a surface parallel to the paper surface of FIG. 3) through which the laser beam 302 passes the measurement object 301 is defined. Next, by driving the piezoelectric element 306, the total reflection mirror 307 is moved in the direction of arrow S, and the laser beam 302 is scanned as shown in FIG. At the same time, by driving the lens barrel drive unit 308, the focus position of the microscope 309 is moved from the position P1 along the dotted line 370, and the laser beam 3
The microscope 309 is focused on a position where the optical path of 02 and the dotted line 370 intersect. The intensity data of the scattered light obtained along the dotted line 370 by the observation with the microscope 309 is stored in a predetermined column of the image memory circuit 311. In this way, the vertical data with the measurement object 301 is obtained.

Next, the driving motor 304 is driven to shift the total reflection mirror 305 slightly, and vertical data of the adjacent position slightly shifted from the measurement position of the measurement object 301 measured earlier is obtained. The scattered light intensity data in the vertical direction is stored in the column next to the data previously stored in the image memory circuit 311.

In this way, the laser beam 302 is gradually swung by the total reflection mirror 305 in the direction perpendicular to the paper surface of FIG. 3, and the laser beam is scanned by the total reflection mirror 307 as shown in FIG. By repeating the observation, the intensity data of the scattered light in the section including the dotted line 370 of the measuring object 301 in the direction perpendicular to the paper surface is obtained. The intensity data of the scattered light is stored in the image memory circuit 311 as image information.
Until the image information of one cross section is stored, each block operates in cooperation with the control of the synchronizing signal generating circuit 315 based on the control signal from the control circuit 319 as described above to obtain the image information of one cross section. To be

Although the information of the two-dimensional internal defect in the cross section of the measurement object 301 can be obtained by such an operation, the measurement object 301 is further shifted slightly in the left-right direction on the paper surface of FIG. 3 as described above. By performing various measurements, three-dimensional internal defect data can be obtained.

[Effects of the Invention] As described above, according to the present invention, in order to inspect internal defects in an object to be measured, the incident position of the laser beam on the object to be measured is moved and interlocked with the movement of the incident position. Since the focus of the optical means is automatically adjusted to the position on the optical path of the laser beam, the distribution of the internal defects in the measurement object in any direction, for example, the vertical internal defects of a silicon wafer or the like. Can be measured nondestructively. Further, by appropriately setting the direction of the laser beam and the observation direction of the optical means, it is possible to prevent a small internal defect from being buried in a large internal defect and prevent accurate inspection.

Further, the laser beam is incident on the measuring object such that the laser beam incident from the first surface of the measuring object is totally reflected on the second surface, and scattered light by the laser beam passing near the second surface is obtained. Since it is observed by an optical means, it is possible to inspect defects near the surface of the measuring object.

[Brief description of drawings]

FIG. 1 (a) is a sectional view showing an optical path of a laser beam in a measurement object in an internal defect inspection apparatus according to an embodiment of the present invention, and FIG. 1 (b) is FIG. 1 (a). 2 is a perspective view of the measurement object of FIG. 2, FIG. 2 is a cross-sectional view showing how scattered light is generated from an internal defect when a laser beam travels through the measurement object, and FIG. 3 is an internal defect of this embodiment. FIG. 4 is a block diagram showing a schematic configuration of an inspection device, FIG. 4 is a conceptual diagram of a conventional internal defect inspection device using transmitted light, and FIGS. 5 (a) to 5 (c) are laser beams for a conventional measurement object. FIG. 3 is a conceptual diagram of an internal defect inspection apparatus of a type in which is incident and is observed from a direction orthogonal to the direction of a laser beam. 101: object to be measured, 102: microscope, 103: imager (detection element), 131 to 134: laser beam, 203: scattered light, 204: defective part, 302: laser beam, 303: laser oscillator, 304: for driving Motor, 305, 307: Total reflection mirror, 306: Piezoelectric element, 308:
Lens barrel drive unit, 309: Microscope, 310: Imager, 311: Image memory circuit, 312: Image processing circuit, 313: Arithmetic processing circuit, 314: Autofocus control circuit, 315: Synchronous signal generation circuit, 316: Display processing Circuit, 317: display circuit, 318: recorder, 319: control circuit, 320: laser power supply, 321: high voltage generation circuit, 322: motor signal generation circuit.

Claims (2)

[Claims] 1. A defect inside the object to be measured is obtained by causing a laser beam that is narrowed down to enter the object to be measured and causing scattered light from the inside of the object to be measured by the laser beam to enter optical means to obtain image information. In an internal defect inspection method for inspecting, a laser beam is applied to an object to be measured such that the laser beam incident from the first surface of the object to be measured is totally reflected on the second surface of the object to be measured. An internal defect inspection method, which comprises injecting the light scattered by a laser beam that passes through the vicinity of the second surface into the optical means to inspect defects near the second surface. 2. A laser emitting means for emitting a laser beam narrowed down, an incident position moving means for moving an incident position of the laser beam on the first surface of the measuring object, and a first measuring object for the measuring object. Incident direction control means for controlling the incident direction of the laser beam to the measurement object so that the laser beam incident from the surface of the laser beam is totally reflected by the second surface of the measurement object, and the measurement object by the laser beam. Optical means for receiving scattered light from the inside as image information, and, in conjunction with the movement of the incident position of the laser beam, focus the optical means on the measurement position in the optical path of the laser beam in the measuring object. Focusing means for adjusting the focus of the optical means to a measurement position in an optical path of a laser beam passing through the vicinity of the second surface of the object to be measured and totally reflecting the second surface of the object to be measured, The light scattered by Zabimu by incident on the optical means, the internal defect inspection apparatus characterized by inspecting defects of a second near the surface.